Carbonized Polymer Dots for Controlling Construction of MoS2 Flower-Like Nanospheres to Achieve High-Performance Li/Na Storage Devices

Despite being one of the most promising materials in anode materials, molybdenum sulfide (MoS2 ) encounters certain obstacles, such as inadequate cycle stability, low conductivity, and unsatisfactory charge-discharge (CD) rate performance. In this study, a novel approach is employed to address the drawbacks of MoS2 . Carbon polymer dots (CPDs) are incorporated to prepare three-dimensional (3D) nanoflower-like spheres of MoS2 @CPDs through the self-assembly of MoS2 2D nanosheets, followed by annealing at 700 °C. The CPDs play a main role in the creation of the nanoflower-like spheres and also mitigate the MoS2 nanosheet limitations. The nanoflower-like spheres minimize volume changes during cycling and improve the rate performance, leading to exceptional rate performance and cycling stability in both Lithium-ion and Sodium-ion batteries (LIBs and SIBs). The optimized MoS2 @CPDs-2 electrode achieves a superb capacity of 583.4 mA h g-1 at high current density (5 A g-1 ) after 1000 cycles in LIBs, and the capacity remaining of 302.8 mA h g-1 after 500 cycles at 5 A g-1 in SIBs. Additionally, the full cell of LIBs/SIBs exhibits high capacity and good cycling stability, demonstrating its potential for practical application in fast-charging and high-energy storage.

High-Efficiency Separator Capacity-Compensation Strategy Applied to Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are expected to replace partial reliance on lithium-ion batteries (LIBs) in the field of large-scale energy storage as well as low-speed electric vehicles due to the abundance, wide distribution, and easy availability of sodium metal. Unfortunately, a certain amount of sodium ions are irreversibly trapped in the solid electrolyte interface (SEI) layer during the initial charging process, causing the initial capacity loss (ICL) of the SIBs. A separator capacity-compensation strategy is proposed, where the capacity compensator on the separator oxidizes below the high cut-off voltage of the cathode to provide additional sodium ions. This strategy shows attractive advantages, including adaptability to current production processes, no impairment of cell long-cycle life, controlled pre-sodiation degree, and strategy universality. The separator capacity-compensation strategy is applied in the NaNi1/3 Fe1/3 Mn1/3 O2 (NMFO)||HC full cell and achieve a compensated capacity ratio of 18.2%. In the Na3 V2 (PO4 )3 (NVP)||HC full cell, the initial reversible specific capacity is increased from 61.0 mAh g-1 to 83.1 mAh g-1 . The separator capacity-compensation strategy is proven to be universal and provides a new perspective to enhance the energy density of SIBs.

FeN Coordination Induced Ultralong Lifetime of Sodium-Ion Battery with the Cycle Number Exceeding 65 000

Sodium-ion batteries (SIBs) have received increasing attention because of their appealing cell voltages and cost-effective features. However, the atom aggregation and electrode volume variation inevitably deteriorate the sodium storage kinetics. Here a new strategy is proposed to boost the lifetime of SIB by synthesizing sea urchin-like FeSe2 /nitrogen-doped carbon (FeSe2 /NC) composites. The robust FeN coordination hinders the Fe atom aggregation and accommodates the volume expansion, while the unique biomorphic morphology and high conductivity of FeSe2 /NC enhance the intercalation/deintercalation kinetics and shorten the ion/electron diffusion length. As expected, FeSe2 /NC electrodes deliver excellent half (387.6 mAh g-1 at 20.0 A g-1 after 56 000 cycles) and full (203.5 mAh g-1 at 1.0 A g-1 after 1200 cycles) cell performances. Impressively, an ultralong lifetime of SIB composed of FeSe2 /Fe3 Se4 /NC anode is uncovered with the cycle number exceeding 65 000. The sodium storage mechanism is clarified with the aid of density function theory calculations and in situ characterizations. This work hereby provides a new paradigm for enhancing the lifetime of SIB by constructing a unique coordination environment between active material and framework.

Cycling Stability of Lithium-Ion Batteries Based on Fe-Ti-Doped LiNi0.5 Mn1.5 O4 Cathodes, Graphite Anodes, and the Cathode-Additive Li3 PO4

This study addresses the improved cycling stability of Li-ion batteries based on Fe-Ti-doped LiNi0.5 Mn1.5 O4 (LNMO) high-voltage cathode active material and graphite anodes. By using 1 wt% Li3 PO4 as cathode additive, over 90% capacity retention for 1000 charge-discharge cycles and remaining capacities of 109 mAh g-1 are reached in a cell with an areal capacity of 2.3 mAh cm- 2 (potential range: 3.5-4.9 V). Cells without the additive, in contrast, suffer from accelerated capacity loss and increase polarization, resulting in capacity retention of only 78% over 1000 cycles. An electrolyte consisting of ethylene carbonate, dimethyl carbonate, and LiPF6 is used without additional additives. The significantly improved cycling stability of the full cells is mainly due to two factors, namely, the low MnIII content of the Fe-Ti-doped LNMO active material and the use of the cathode-additive Li3 PO4 . Crystalline Li3 PO4 yields a drastic reduction of transition metal deposition on the graphite anode and prevents Li loss and the propagation of cell polarization. Li3 PO4 is added to the cathode slurry that makes it a very simple and scalable process, first reported herein. The positive effects of crystalline Li3 PO4 as electrode additive, however, should apply to other cell chemistries as well.

Hierarchical 3D Porous Hydrogen-Substituted Graphdiyne for High-Performance Electrochemical Lithium-Ion Storage

Graphdiyne (GDY) has realized significant achievements in lithium-ion batteries (LIBs) because of its unique π-conjugated skeleton with sp- and sp²-hybridized carbon atoms. Enriching the accessible surface areas and diffusion pathways of Li ions can realize more storage sites and rapid transport dynamics. Herein, three-dimensional porous hydrogen-substituted GDY (HsGDY) is developed for high-performance Li-ion storage. HsGDY, fabricated via a versatile interface-assisted synthesis strategy, exhibits a large specific surface area (667.9 m² g^-1), a hierarchical porous structure, and an expanded interlayer space, which accelerate Li-ion accessibility and lithiation/delithiation. Owing to this high π-conjugated, conductive, and porous framework, HsGDY exhibits a large reversible capacity (930 mA h g^-1 after 100 cycles at 1 A g^-1), superior cycle (720 mA h g^-1 after 300 cycles at 1 A g^-1), and rate (490 mA h g^-1 at 5 A g^-1) performances. Density functional theory calculations of the low diffusion barrier in the lamination and vertical directions further reveal the fast Li-ion transport kinetics of HsGDY. Additionally, a LiCoO₂-HsGDY full cell is constructed, which exhibits a good practical charge/discharge capacity of 128 mA h g^-1 and stable cycling behavior. This study highlights the advanced design of next-generation LIBs to sustainably develop the new energy industry.

P-Doping a Porous Carbon Host Promotes the Lithium Storage Performance of Red Phosphorus

Red phosphorus (RP) is a promising anode material for use in lithium-ion batteries (LIBs) due to its high theoretical specific capacity (2596 mA h g^-1). However, the practical use of RP-based anodes has been challenged by the material's low intrinsic electrical conductivity and poor structural stability during lithiation. Here, we describe a phosphorus-doped porous carbon (P-PC) and disclose how the dopant improves the Li storage performance of RP that was incorporated into the P-PC (designated as RP@P-PC). P-doping porous carbon was achieved using an in situ method wherein the heteroatom was added as the porous carbon was being formed. The phosphorus dopant effectively improves the interfacial properties of the carbon matrix as subsequent RP infusion results in high loadings, small particle sizes, and uniform distribution. In half-cells, an RP@P-PC composite was found to exhibit outstanding performance in terms of the ability to store and utilize Li. The device delivered a high specific capacitance and rate capability (1848 and 1111 mA h g^-1 at 0.1 and 10.0 A g^-1, respectively) as well as excellent cycling stability (1022 mA h g^-1 after 800 cycles at 2.0 A g^-1). Exceptional performance metrics were also measured when the RP@P-PC was used as an anode material in full cells that contained lithium iron phosphate as the cathode material. The methodology described can be extended to the preparation of other P-doped carbon materials that are employed in contemporary energy storage applications.

Iodine-Ion-Assisted Galvanic Replacement Synthesis of Bismuth Nanotubes for Ultrafast and Ultrastable Sodium Storage

Bismuth (Bi) has emerged as a promising anode material for fast-charging and long-cycling sodium-ion batteries (SIBs). However, its dramatically volumetric variations during cycling will undesirably cause the pulverization of active materials, severely limiting the electrochemical performance of Bi-based electrodes. Constructing hollow nanostructures is recognized as an effective way to resolve the volume expansion issues of alloy-type anodes but remains a great challenge for metallic bismuth. Here, we report a facile iodine-ion-assisted galvanic replacement approach for the synthesis of Bi nanotubes (NTs) for high-rate, long-term and high-capacity sodium storage. The hollow tubular structure effectively alleviates the structural strain during sodiation/desodiation processes, resulting in excellent structural stability; the thin wall and large surface area enable ultrafast sodium ion transport. Benefiting from the structural merits, the Bi NT electrode exhibits extraordinary rate capability (84% capacity retention at 150 A g^-1) and outstanding cycling stability (74% capacity retention for 65,000 cycles at 50 A g^-1), which represent the best rate performance and longest cycle life among all reported anodes for SIBs. Moreover, when coupled with the Na₃(VOPO₄)₂F cathode in full cells, this electrode also demonstrates excellent cycling performance, showing the great promise of Bi NTs for practical application. A combination of advanced research techniques reveals that the excellent performance originates from the structural robustness of the Bi NTs and the fast electrochemical kinetics during cycling.

Organic Small Molecules with Electrochemical-Active Phenolic Enolate Groups for Ready-to-Charge Organic Sodium-Ion Batteries

Organic materials have attracted much attention in sodium ion batteries (SIBs) because of their advantages such as being environmentally benign and having high designability. Capacities and cycle life of organic materials are the most important parameters in most research which has been paid much effort to obtain an impressive electrochemical performance on the material level, and the sodium-detachable ability of these materials to directly match with the sodium-free anode is neglected. In this work, one organic sodium salt (C₆ H₂ Na₂ O₆ ) exhibits the unique ability (charging first in half cell) unlike other reported organic cathode materials (normally discharging first) for SIBs. The redox mechanism and structure change are investigated by in situ and ex situ tests to give a better understanding for C₆ H₂ Na₂ O₆ . Satisfying electrochemical performance (74% capacity retention after 600 cycles at 0.05 A g^-1 and 63% capacity retention at 5 A g^-1 when compared with capacity at 0.05 A g^-1 ) is achieved by the C₆ H₂ Na₂ O₆ electrode. In addition, matched with hard carbon, full cells are assembled successfully like other transition metal containing cathode materials because C₆ H₂ Na₂ O₆ electrode can deliver its sodium ions to a sodium-free anode directly without any presodiation.

Iron Selenide-Based Heterojunction Construction and Defect Engineering for Fast Potassium/Sodium-Ion Storage

Suitable anode materials with high capacity and long cycling stability, especially capability at high current densities, are urgently needed to advance the development of potassium ion batteries (PIBs) and sodium ion batteries (SIBs). Herein, a porous Ni-doped FeSe₂ /Fe₃ Se₄ heterojunction encapsulated in Se-doped carbon (NF₁₁ S/C) is designed through selenization of MOFs precursor. The porous composite possesses enriched active sites and facilitates transport for both ion and electron. Ni-doping is adopted to enrich the lattice defects and active sites. The Se-C bond and carbon framework endow integrity of the composite and hamper aggregation of selenide nano-particles during potassiation/de-potassiation. The NF₁₁ S/C exhibits exceptional rate performance and ultra-long cycling stability (177.3 mA h g^-1 after 3050 cycles at 2 A g^-1 for PIBs and 208.8 mA h g^-1 after 2000 cycles at 8 A g^-1 for SIBs). The potassiation/de-potassiation mechanism is investigated via ex-situ X-ray powder diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectrocopy and Raman analysis. PTCDA//NF₁₁ S/C full cell stably cycles for 1200 cycles at 200 mA g^-1 with a capacity of 103.7 mA h g^-1 , indicating the high application potential of the electrode for highly stable rechargeable batteries.

Ultrastable and High Energy Calcium Rechargeable Batteries Enabled by Calcium Intercalation in a NASICON Cathode

Ca-ion batteries (CIBs) have been considered a promising candidate for the next-generation energy storage technology owing to the abundant calcium element and the low reduction potential of Ca²⁺ /Ca. However, the large size and divalent nature of Ca²⁺ induce significant volume change and sluggish ion mobility in intercalation cathodes, leading to poor reversibly and low energy/power densities for CIBs. Herein, a polyanionic Na superionic conduction (NASICON)-typed Na-vacant Na₁ V₂ (PO₄ )₂ F₃ (N₁ PVF₃ ) with sufficient interstitial spaces is reported as ultra-stable and high-energy Ca ion cathodes. The N₁ PVF₃ delivers exceptionally high Ca storage capacities of 110 and 65 mAh g^-1 at 10 and 500 mA g^-1 , respectively, and a record-long cyclability of 2000 cycles. More interestingly, by tailoring the fluorine content in N₁ PVF_x (1 ≤ x ≤ 3), the high working potential of 3.5 V versus Ca²⁺ /Ca is achievable. In conjunction with Ca metal anode and a compatible electrolyte, Ca metal batteries with N₁ VPF₃ cathodes are constructed, which deliver an initial energy density of 342 W h kg^-1 , representing one of the highest values thus far reported for CIBs. Origins of the uncommonly stable and high-power capabilities for N₁ PVF₃ are elucidated as the small volume changes and low cation diffusion barriers among the cathodes.

Tailoring MSx Quantum Dots (M = Co, Ni, Cu, Zn) for Advanced Energy Storage Materials with Strong Interfacial Engineering

Metal sulfides, as vital members of electrodes materials, still suffer from serious volume expansion and polysulfides shuttling. Herein, through inexpensive and high efficiency chemical-bonding/hydrophobic-association methods, a series of metal-sulfides quantum dots (QDs) with large-scale synthesis (≈100 g) is successfully prepared, further forming low-dimensional composites with high redox activity. For the derived electrodes samples, with the increasing of outer electron numbers (Co²⁺ /Ni²⁺ /Cu²⁺ /Zn²⁺ ), interfacial coupling is significantly modified. Among them, nanoscale ZnS@double carbon with rich interfacial Zn-O/S-C bonds displays remarkable electrochemical activity, with the capacity of ≈1000 mAh g^-1 after 100 loops. Through tailoring double carbons and interfacial merits, in situ sulfur formation is stabilized, and the cycling stability of Zn-based samples can increase up to 4000 cycles. Even at 5.0 A g^-1 after 1500 cycles, the full-cells capacity can reach up to ≈380 mAh g^-1 . Supported by detailed kinetic analysis and ex situ technologies, the enhanced interfacial capacitances and ions moving are confirmed for the improved electrochemical properties. Given this, the work is expected to boost future developments of mineral processing, and QDs preparation, whilst providing effective strategies for advanced electrode materials.

Versatile Preparation of Mesoporous Single-Layered Transition-Metal Sulfide/Carbon Composites for Enhanced Sodium Storage

Transition-metal sulfides are promising electrochemical energy storage materials due to their abundant active sites, large interlayer space, and high theoretical capacities, especially for sodium storage. However, the low conductivity and poor cycling stability at high current densities hamper their applications. Herein, a versatile dual-template method is reported to elaborate ordered mesoporous single-layered MoS₂ /carbon composite with high specific area, uniform pore size, and large pore volume. The single-layered MoS₂ is confined in the carbon matrix. The mesopores between the composite nanorods provide fast electrolyte diffusion. The obtained nanocomposite shows a high sodium-storage capability, excellent rate capacity, and very good cycling performance. A capacity of 310 mAh g^-1 can remain at 5.0 A g^-1 after 2500 cycles. Furthermore, a sodium-ion battery (SIB) full cell composed of the MoS₂ /carbon composite anode and a Na₃ V₂ (PO₄ )₃ (NVP) cathode maintains a specific capacity of 330 mAh g^-1 at 1.0 A g^-1 during 100 cycles. The mechanism is investigated by in situ and ex situ characterizations as well as density functional theory (DFT) calculations.

Ether-Based Electrolyte Chemistry Towards High-Voltage and Long-Life Na-Ion Full Batteries

Although ether-based electrolytes have been extensively applied in anode evaluation of batteries, anodic instability arising from solvent oxidability is always a tremendous obstacle to matching with high-voltage cathodes. Herein, by rational design for solvation configuration, the fully coordinated ether-based electrolyte with strong resistance against oxidation is reported, which remains anodically stable with high-voltage Na₃ V₂ (PO₄ )₂ O₂ F (NVPF) cathode under 4.5 V (versus Na⁺ /Na) protected by an effective interphase. The assembled graphite//NVPF full cells display superior rate performance and unprecedented cycling stability. Beyond that, the constructed full cells coupling the high-voltage NVPF cathode with hard carbon anode exhibit outstanding electrochemical performances in terms of high average output voltage up to 3.72 V, long-term cycle life (such as 95 % capacity retention after 700 cycles) and high energy density (247 Wh kg^-1 ). In short, the optimized ether-based electrolyte enriches systematic options, the ability to maintain oxidative stability and compatibility with various anodes, exhibiting attractive prospects for application.

Ti3 C2 Tx MXene Conductive Layers Supported Bio-Derived Fex -1 Sex /MXene/Carbonaceous Nanoribbons for High-Performance Half/Full Sodium-Ion and Potassium-Ion Batteries

Owing to their cost-effectiveness and high energy density, sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are becoming the leading candidates for the next-generation energy-storage devices replacing lithium-ion batteries. In this work, a novel Fe_{x -1} Se_x heterostructure is prepared on fungus-derived carbon matrix encapsulated by 2D Ti₃ C₂ T_x MXene highly conductive layers, which exhibits high specific sodium ion (Na⁺ ) and potassium ion (K⁺ ) storage capacities of 610.9 and 449.3 mAh g^-1 at a current density of 0.1 A g^-1 , respectively, and excellent capacity retention at high charge-discharge rates. MXene acts as conductive layers to prevent the restacking and aggregation of Fe_{x -1} Se_x sheets on fungus-derived carbonaceous nanoribbons, while the natural fungus functions as natural nitrogen/carbon source to provide bionic nanofiber network structural skeleton, providing additional accessible pathways for the high-rate ion transport and satisfying surface-driven contribution ratios at high sweep rates for both Na/K ions storages. In addition, in situ synchrotron diffraction and ex situ X-ray photoelectron spectroscopy measurements are performed to reveal the mechanisms of storage and de-/alloying conversion process of Na⁺ in the Fe_{x -1} Se_x /MXene/carbonaceous nanoribbon heterostructure. As a result, the assembled Na/K full cells containing MXene-supported Fe_{x -1} Se_x @carbonaceous anodes possess stable large-ion storage capabilities.

Aliovalent-Ion-Induced Lattice Regulation Based on Charge Balance Theory: Advanced Fluorophosphate Cathode for Sodium-Ion Full Batteries

There are still many problems that hinder the development of sodium-ion batteries (SIBs), including poor rate performance, short-term cycle lifespan, and inferior low-temperature property. Herein, excellent Na-storage performance in fluorophosphate (Na₃ V₂ (PO₄ )₂ F₃ ) cathode is achieved by lattice regulation based on charge balance theory. Lattice regulation of aliovalent Mn²⁺ for V³⁺ increases both electronic conductivity and Na⁺ -migration kinetics. Because of the maintaining of electrical neutrality in the material, aliovalent Mn²⁺ -introduced leads to the coexistence of V³⁺ and V⁴⁺ from charge balance theory. It decreases the particle size and improves the structural stability, suppressing the large lattice distortion during cathode reaction processes. These multiple effects enhance the specific capacity (123.8 mAh g^-1 ), outstanding high-rate (68% capacity retention at 20 C), ultralong cycle (only 0.018% capacity attenuation per cycle over 1000 cycles at 1 C) and low-temperature (96.5% capacity retention after 400 cycles at -25 °C) performances of Mn²⁺ -induced Na₃ V_1.98 Mn_0.02 (PO₄ )₂ F₃ when used as cathode in SIBs. Importantly, a feasible sodium-ion full battery is assembled, achieving outstanding rate capability and cycle stability. The strategy of aliovalent ion-induced lattice regulation constructs cathode materials with superior performances, which is available to improve other electrode materials for energy storage systems.

(NH4 )2 V7 O16 Microbricks as a Novel Anode for Aqueous Lithium-Ion Battery with Good Cyclability

Searching for novel anode materials to address the issues of poor cycle stability in the aqueous lithium-ion battery system is highly desirable. In this work, ammonium vanadium bronze (NH₄ )₂ V₇ O₁₆ with brick-like morphology has been investigated as an anode material for aqueous lithium-ion batteries and Li⁺ /Na⁺ hybrid ion batteries. The two novel full cell systems (NH₄ )₂ V₇ O₁₆ ||Li₂ SO₄ ||LiMn₂ O₄ and (NH₄ )₂ V₇ O₁₆ ||Na₂ SO₄ ||LiMn₂ O₄ both demonstrate good rate capability and excellent cycling performance. A capacity retention of 78.61 % after 500 cycles at 300 mA g^-1 was demonstrated in the (NH₄ )₂ V₇ O₁₆ ||Li₂ SO₄ ||LiMn₂ O₄ system, whereas no capacity attenuation is observed in the (NH₄ )₂ V₇ O₁₆ ||Na₂ SO₄ ||LiMn₂ O₄ system. The reaction mechanisms of the (NH₄ )₂ V₇ O₁₆ electrode and impedance variation of the two full cells were also researched. The excellent cycling stability suggests that layered (NH₄ )₂ V₇ O₁₆ can be a promising anode material for aqueous rechargeable lithium-ion batteries.

Boosting Potassium Storage by Integration Advantageous of Defect Engineering and Spatial Confinement: A Case Study of Sb2 Se3

The potassium ion batteries (KIBs) based on conversion/alloying reaction mechanisms show high theoretical capacity. However, their applications are hampered by the poor cyclability resulting from the inherent large volume variations and the sluggish kinetics during K⁺ repeated insertion/extraction process. Herein, taken Sb₂ Se₃ as a model material, by rational design, nickel doped-carbon coated Sb₂ Se₃ nanorods (denoted as (Sb_0.99 Ni_0.01 )₂ Se₃ @C) are prepared through combined strategies of the conductive encapsulation and crystal structure modification. The carbon coating acts as an efficient buffer layer that maintains superior structural stability upon cycling. The introduction of Ni atoms can enhance electrical conductivity, leading to outstanding rate performance, which are confirmed by density functional theory calculation. The (Sb_0.99 Ni_0.01 )₂ Se₃ @C displays excellent reversible capacity (410 mAh g^-1 at 0.1 A g^-1 after 100 cycles) and unprecedented rate capability (140 mAh g^-1 at 10 A g^-1 ). Furthermore, KFeHCF//(Sb_0.99 Ni_0.01 )₂ Se₃ @C full cell exhibits a high specific capacity (408 mAh g^-1 at 0.1 A g^-1 ), superior rate capability (260 mAh g^-1 at 2 A g^-1 ). This work can open up a new avenue for the design of stable conversion/alloying-based anodes for high energy density KIBs.

Rational Design of Sb@C@TiO2 Triple-Shell Nanoboxes for High-Performance Sodium-Ion Batteries

Antimony is an attractive anode material for sodium-ion batteries (SIBs) owing to its high theoretical capacity and appropriate sodiation potential. However, its practical application is severely impeded by its poor cycling stability caused by dramatic volumetric variations during sodium uptake and release processes. Here, to circumvent this obstacle, Sb@C@TiO₂ triple-shell nanoboxes (TSNBs) are synthesized through a template-engaged galvanic replacement approach. The TSNB structure consists of an inner Sb hollow nanobox protected by a conductive carbon middle shell and a TiO₂ -nanosheet-constructed outer shell. This structure offers dual protection to the inner Sb and enough room to accommodate volume expansion, thus promoting the structural integrity of the electrode and the formation of a stable solid-electrolyte interface film. Benefiting from the rational structural design and synergistic effects of Sb, carbon, and TiO₂ , the Sb@C@TiO₂ electrode exhibits superior rate performance (212 mAh g^-1 at 10 A g^-1 ) and outstanding long-term cycling stability (193 mAh g^-1 at 1 A g^-1 after 4000 cycles). Moreover, a full cell assembled with a configuration of Sb@C@TiO₂ //Na₃ (VOPO₄ )₂ F displays a high output voltage of 2.8 V and a high energy density of 179 Wh kg^-1 , revealing the great promise of Sb@C@TiO₂ TSNBs as the electrode in SIBs.

Bottom-Up Synthesis of MoS2 /CNTs Hollow Polyhedron with 1T/2H Hybrid Phase for Superior Potassium-Ion Storage

Enslaved to the large-size K-ions, the construction of suitable anode materials with superior and stable potassium-ion storage properties is a major challenge. 1T phase MoS₂ possesses higher conductivity, bigger interlayer distance, and more electrochemically active sites than the 2H phase, which offers intriguing benefits for energy-related applications. In this work, the 1T/2H-phase hybrid MoS₂ nanosheets are successfully anchored in the N-doped carbon nanotube hollow polyhedron (1T/2H-MoS₂ /NCNHP) by a bottom-up solvothermal method. For the synthesized 1T/2H-MoS₂ /NCNHP, the fewer-layer 1T/2H-MoS₂ nanosheets are embedded in an N-doped carbon nanotube hollow polyhedron, with an enlarged interlayer spacing of 0.96 nm. When evaluated as anode material for potassium-ion batteries, the 1T/2H-MoS₂ /NCNHP hybrid presents outstanding potassium storage performance. It delivers a high-specific capacity of 519.2 mAh g^-1 at 50 mA g^-1 and maintains 281.2 mAh g^-1 at 1 A g^-1 over 500 cycles. The good potassium-ion electrochemical performance is attributed to the rational structural design and the synergistic effect of the components. Moreover, the 1T-MoS₂ nanosheet has excellent electrical conductivity and its enlarged interlayer spacing reduces the barrier for the embedding and stripping of K ions. Finally, the practical application of the 1T/2H-MoS₂ /NCNHP electrode material is also evaluated by assembled K-ion full cells.

High-Efficiency Cathode Sodium Compensation for Sodium-Ion Batteries

Sodium-ion batteries have gained much attention for their potential application in large-scale stationary energy storage due to the low cost and abundant sodium sources in the earth. However, the electrochemical performance of sodium-ion full cells (SIFCs) suffers severely from the irreversible consumption of sodium ions of cathode during the solid electrolyte interphase (SEI) formation of hard carbon anode. Here, a high-efficiency cathode sodiation compensation reagent, sodium oxalate (Na₂ C₂ O₄ ), which possesses both a high theoretical capacity of 400 mA h g^-1 and a capacity utilization as high as 99%, is proposed. The implementation of Na₂ C₂ O₄ as sacrificial sodium species is successfully realized by decreasing its oxidation potential from 4.41 to 3.97 V through tuning conductive additives with different physicochemical features, and the corresponding mechanism of oxidation potential manipulation is analyzed. Electrochemical results show that in the full cell based on a hard carbon anode and a P2-Na_2/3 Ni_1/3 Mn_1/3 Ti_1/3 O₂ cathode with Na₂ C₂ O₄ as a sodium reservoir to compensate for sodium loss during SEI formation, the capacity retention is increased from 63% to 85% after 200 cycles and the energy density is improved from 129.2 to 172.6 W h kg^-1 . This work can provide a new avenue for accelerating the development of SIFCs.

Controllable Synthesis of Peapod-like Sb@C and Corn-like C@Sb Nanotubes for Sodium Storage

Antimony (Sb) is regarded as an attractive anode material for sodium-ion batteries (SIBs) due to its high theoretical capacity of 660 mAh g^-1. Combining Sb with carbonaceous materials has been considered as an effective way to resolve the serious volume expansion issues. Sb/C composites mainly consist of two types, that is, Sb confined inside a carbon matrix and Sb deposited on the surface of a carbon matrix, and both have shown superior sodium storage performance. However, which structure is more beneficial for achieving high electrochemical performance is still unclear. In this work, peapod-like Sb@C and corn-like C@Sb nanotubes are synthesized via a nanoconfined galvanic replacement reaction and used as model materials for sodium storage to explore the above issue. When evaluated as anode materials for SIBs, the peapod-like Sb@C shows a higher rate capability and a significantly better long-term cycling stability compared to those of the corn-like C@Sb. Electrochemical analysis reveals that the peapod-like Sb@C exhibits faster Na⁺ and electron transport kinetics and higher proportions of surface capacitive contributions. These results demonstrate the structural superiority of the nanoconfined structure and provide valuable information for the rational design and construction of Sb-based anode materials for high-performance electrochemical energy storage.

Construction of Bimetallic Selenides Encapsulated in Nitrogen/Sulfur Co-Doped Hollow Carbon Nanospheres for High-Performance Sodium/Potassium-Ion Half/Full Batteries

Metallic selenides have been widely investigated as promising electrode materials for metal-ion batteries based on their relatively high theoretical capacity. However, rapid capacity decay and structural collapse resulting from the larger-sized Na⁺ /K⁺ greatly hamper their application. Herein, a bimetallic selenide (MoSe₂ /CoSe₂ ) encapsulated in nitrogen, sulfur-codoped hollow carbon nanospheres interconnected reduced graphene oxide nanosheets (rGO@MCSe) are successfully designed as advanced anode materials for Na/K-ion batteries. As expected, the significant pseudocapacitive charge storage behavior substantially contributes to superior rate capability. Specifically, it achieves a high reversible specific capacity of 311 mAh g^-1 at 10 A g^-1 in NIBs and 310 mAh g^-1 at 5 A g^-1 in KIBs. A combination of ex situ X-ray diffraction, Raman spectroscopy, and transmission electron microscopy tests reveals the phase transition of rGO@MCSe in NIBs/KIBs. Unexpectedly, they show quite different Na⁺ /K⁺ insertion/extraction reaction mechanisms for both cells, maybe due to more sluggish K⁺ diffusion kinetics than that of Na⁺ . More significantly, it shows excellent energy storage properties in Na/K-ion full cells when coupled with Na₃ V₂ (PO₄ )₂ O₂ F and PTCDA@450 °C cathodes. This work offers an advanced electrode construction guidance for the development of high-performance energy storage devices.

Tailoring Coral-Like Fe7Se8@C for Superior Low-Temperature Li/Na-Ion Half/Full Batteries: Synthesis, Structure, and DFT Studies

The intrinsic charge-transfer property bears the primary responsibility for the sluggish redox kinetics of the common electrode materials, especially operated at low temperatures. Herein, we report the crafting of homogeneously confined Fe₇Se₈ nanoparticles with a well-defined graphitic carbon matrix that demonstrate a highly efficient charge-transfer system in a designed natural coral-like structure (cl-Fe₇Se₈@C). Notably, the intricate architecture as well as highly conductive peculiarity of C concurrently satisfy the demands of achieving fast ionic/electrical conductivities for both Li/Na-ion batteries in a wide temperature range. For example, when cl-Fe₇Se₈@C is employed as the anode material to assemble full batteries with the cathode of Na₃V₂(PO₄)₂O₂F (NVPOF), decent capacities of 323.1 and 175.9 mA h g^-1 can be acquired at temperatures of 25 and -25 °C, respectively. This work is significant for further developing potential anode materials for advanced energy storage and conversion under low-temperature conditions.

A 3D Lithiophilic Mo2 N-Modified Carbon Nanofiber Architecture for Dendrite-Free Lithium-Metal Anodes in a Full Cell

The pursuit for high-energy-density batteries has inspired the resurgence of metallic lithium (Li) as a promising anode, yet its practical viability is restricted by the uncontrollable Li dendrite growth and huge volume changes during repeated cycling. Herein, a new 3D framework configured with Mo₂ N-mofidied carbon nanofiber (CNF) architecture is established as a Li host via a facile fabrication method. The lithiophilic Mo₂ N acts as a homogeneously pre-planted seed with ultralow Li nucleation overpotential, thus spatially guiding a uniform Li nucleation and deposition in the matrix. The conductive CNF skeleton effectively homogenizes the current distribution and Li-ion flux, further suppressing Li-dendrite formation. As a result, the 3D hybrid Mo₂ N@CNF structure facilitates a dendrite-free morphology with greatly alleviated volume expansion, delivering a significantly improved Coulombic efficiency of ≈99.2% over 150 cycles at 4 mA cm^-2 . Symmetric cells with Mo₂ N@CNF substrates stably operate over 1500 h at 6 mA cm^-2 for 6 mA h cm^-2 . Furthermore, full cells paired with LiNi_0.8 Co_0.1 Mn_0.1 O₂ (NMC811) cathodes in conventional carbonate electrolytes achieve a remarkable capacity retention of 90% over 150 cycles. This work sheds new light on the facile design of 3D lithiophilic hosts for dendrite-free lithium-metal anodes.

High-Performance Lithiated SiOx Anode Obtained by a Controllable and Efficient Prelithiation Strategy

Silicon-based electrodes are promising and appealing for futuristic Li-ion batteries because of their high theoretical specific capacity. However, massive volume change of silicon upon lithiation and delithiation, accompanied by continual formation and destruction of the solid-electrolyte interface (SEI), leads to low Coulombic efficiency. Prelithiation of Si-based anode is regarded as an effective way for compensating for the loss of Li⁺ in the first discharging process. Here, a high-performance lithiated SiO_x anode was prepared by using a controllable, efficient, and novel prelithiation strategy. The lithiation of SiO_x is homogeneous and efficient in bulk due to well-improved Li⁺ diffusion in SiO_x. Moreover, the in situ formed SEI during the process of prelithiation reduces the irreversible capacity loss in the first cycle and thus improves the initial Coulombic efficiency (ICE). Half-cells and full cells based on the as-prepared lithiated SiO_x anode prominently increase the ICE from 79 to 89% and 68 to 87%, respectively. It is worth mentioning that the homogeneously lithiated SiO_x anode achieves stable 200 cycles in NCM622//SiO_x coin full cells. These exciting results provide applicable prospects of lithiated SiO_x anode in the next-generation high-energy-density Li-ion batteries.

Nonaqueous Sodium-Ion Full Cells: Status, Strategies, and Prospects

With ever-increasing efforts focused on basic research of sodium-ion batteries (SIBs) and growing energy demand, sodium-ion full cells (SIFCs), as unique bridging technology between sodium-ion half-cells (SIHCs) and commercial batteries, have attracted more and more interest and attention. To promote the development of SIFCs in a better way, it is essential to gain a systematic and profound insight into their key issues and research status. This Review mainly focuses on the interface issues, major challenges, and recent progresses in SIFCs based on diversified electrolytes (i.e., nonaqueous liquid electrolytes, quasi-solid-state electrolytes, and all-solid-state electrolytes) and summarizes the modification strategies to improve their electrochemical performance, including interface modification, cathode/anode matching, capacity ratio, electrolyte optimization, and sodium compensation. Outlooks and perspectives on the future research directions to build better SIFCs are also provided.

Recent Progress of Layered Transition Metal Oxide Cathodes for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are attracting increasing attention and considered to be a low-cost complement or an alternative to lithium-ion batteries (LIBs), especially for large-scale energy storage. Their application, however, is limited because of the lack of suitable host materials to reversibly intercalate Na⁺ ions. Layered transition metal oxides (Na_x MO₂ , M = Fe, Mn, Ni, Co, Cr, Ti, V, and their combinations) appear to be promising cathode candidates for SIBs due to their simple structure, ease of synthesis, high operating potential, and feasibility for commercial production. In the present work, the structural evolution, electrochemical performance, and recent progress of Na_x MO₂ as cathode materials for SIBs are reviewed and summarized. Moreover, the existing drawbacks are discussed and several strategies are proposed to help alleviate these issues. In addition, the exploration of full cells based on Na_x MO₂ cathodes and future perspectives are discussed to provide guidance for the future commercialization of such systems.

SnP3/Carbon Nanocomposite as an Anode Material for Potassium-Ion Batteries

New anode materials with large capacity and long cyclability for next-generation potassium-ion batteries (PIBs) are required. PIBs are in the initial stage of investigation and only a few anode materials have been explored. In this study, for the first time, an SnP₃/C nanocomposite with superior cyclability and rate performance was evaluated as an anode for PIBs. The SnP₃/C nanocomposite was synthesized by a facile and cost-effective high-energy ball-milling technique. The SnP₃/C electrode delivered a first reversible capacity of 410 mAh g^-1 and maintained 408 mAh g^-1 after 50 cycles at a specific current of 50 mA g^-1. After 80 cycles at a high specific current of 500 mA g^-1, a high capacity of 225 mAh g^-1 remained. From a crystallographic analysis, it was suggested that the SnP₃/C nanocomposite underwent a sequential and reversible conversion and alloying reactions. The excellent cycling stability and rate capability of the SnP₃/C electrode were attributed to the nanosized SnP₃ particles and carbon buffer layer, which supplied channels for the migration of K-ions and mitigated the stress induced by a large volume change during potassiation/depotassiation. In addition, a full cell composed of the SnP₃/C nanocomposite anode and potassium Prussian blue cathode exhibited a reversible capacity of 305 mAh g^-1 at a specific current of 30 mA g^-1 and retained 71.7% of the original capacity after 30 cycles. These results are important for understanding the electrochemical process of the SnP₃/C nanocomposite and using the SnP₃/C as an anode for PIBs.

Nitrogen and Phosphorus Codoped Vertical Graphene/Carbon Cloth as a Binder-Free Anode for Flexible Advanced Potassium Ion Full Batteries

With the fast development in flexible electronic technology, power supply devices with high performance, low-cost, and flexibility are becoming more and more important. Potassium ion batteries (KIBs) have a brilliant prospect for applications benefiting from high voltage, lost cost, as well as similar electrochemistry to lithium ion batteries (LIBs). Although carbon materials have been studied as KIBs anodes, their rate capability and cycling stability are still unsatisfactory due to the large-size potassium ions. Herein, a nitrogen (N) and phosphorus (P) dual-doped vertical graphene (N, P-VG) uniformly grown on carbon cloth (N, P-VG@CC) is reported as a binder-free anode for flexible KIBs. With the combined advantages of rich active sites, highly accessible surface, highly conductive network, larger interlayer spacing as well as robust structural stability, this binder-free N, P-VG@CC anode exhibits high capacity (344.3 mAh g^-1 ), excellent rate capability (2000 mA g^-1 ; 46.5% capacity retention), and prominent long-term cycling stability (1000 cycles; 82% capacity retention), outperforming most of the recently reported carbonaceous anodes. Moreover, a potassium ion full cell is successfully assembled on the basis of potassium Prussian blue (KPB)//N, P-VG@CC, exhibiting a large energy density of 232.5 Wh kg^-1 and outstanding cycle stability.

Fe,N-Codoped Graphdiyne Displaying Efficient Oxygen Reduction Reaction Activity

On account of the high-cost of platinum, researchers are working to develop a new catalyst that is cheaper and has a catalytic effect equivalent to platinum. Herein, owing to the unique acetylenic bonds in graphdiyne, iron, nitrogen co-doped graphdiyne (Fe-N-GDY) is a promising nonprecious metal catalyst, which has been developed with just a small amount of iron precursor with the plan to substitute it for Pt-based catalysts. The as-synthesized Fe-N-GDY composited catalyst shows excellent catalytic performance with the onset potential of 0.94 V versus reversible hydrogen electrode and limited current density of 5.4 mA cm^-2 . Moreover, it shows excellent resistance to methanol poisoning and stability in both acidic and alkaline electrolytes, which makes potentially applicable in the oxygen reduction reaction field.

An Ultrafast and Highly Stable Potassium-Organic Battery

Potassium-organic batteries have a great potential for applications in the grid-scale energy storage owing to their low cost and abundant resources, although they suffer from the inferior cycle stability, fast capacity decay, and low power density. A highly reversible phase transformation of the organic cathode during potassiation/depotassiation is the key factor for the capacity retention, as revealed here. Consequently, the potassium-organic battery achieves a high power density of 9796 W kg^-1 , a remarkable energy efficiency of 89%, a long cycle stability for 1000 cycles, a superior areal capacity around 2 mA h cm^-2 , and a long-term cycling time over 8 months. Besides, the full cells also exhibit a superior rate performance and good cycle stability over 3000 cycles. This work provides new insight into the stabilization of the organic cathode, and demonstrates the enormous potential of organic cathodes for application in high-power potassium-ion batteries (PIBs), which may bring PIBs to new heights.

Realizing High-Performance Li-Polysulfide Full Cells by using a Lithium Bis(trifluoromethanesulfonyl)imide Salt Electrolyte for Stable Cyclability

Since concentrated electrolytes have attracted great attention for the stabilization of lithium-metal anodes for lithium-ion batteries, the demonstration of a full cell with an electrolyte concentration study has become a research topic of interest. Herein, we have demonstrated a proof of concept, a lithium-polysulfide full cell battery using various lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte concentrations with glass-fiber-based composite and hard carbon as the cathode and anode, respectively. The initial capacity of the lithium-polysulfide full cell is found to be 970 mA h g^-1 at 0.1 C. The capacity is stabilized at 870 mA h g^-1 after 100 cycles with a capacity retention of 88.6 %. An excellent capacity retention of ≈80 % is achieved after long 800 cycles at 0.5 C by using full cell technology. Further, our post-mortem analysis sheds light on the difference in SEI layer formation on hard carbon anodes with changing electrolyte concentration, thereby indicating reasons for the obtainment of a high cyclic performance with 1 m LiTFSI salt electrolyte. The successful demonstration of the long cyclic performance of Li-polysulfide full cells is indeed a step towards producing high performance Li-polysulfide full cell batteries with long cycling using conventional LiTFSI salt electrolyte and commercial anode materials.

One-Dimensional Integrated MnS@Carbon Nanoreactors Hybrid: An Alternative Anode for Full-Cell Li-Ion and Na-Ion Batteries

Manganese sulfide (MnS) has triggered great interest as an anode material for rechargeable Li-ion/Na-ion batteries (LIBs/SIBs) because of its low cost, high electrochemical activity, and theoretical capacity. Nevertheless, the practical application is greatly hindered by its rapid capacity decay lead by inevitable active dissolutions and volume expansions in charge/discharge cycles. To resolve the above issues in LIBs/SIBs, we herein put forward the smart construction of MnS nanowires embedded in carbon nanoreactors (MnS@C NWs) via a facile solution method followed by a scalable in situ sulfuration treatment. This engineering protocol toward electrode architectures/configurations endows integrated MnS@C NWs anodes with large specific capacity (with a maximum value of 847 mA h g^-1 in LIBs and 720 mA h g^-1 in SIBs), good operation stability, excellent rate capabilities, and prolonged cyclic life span. To prove their potential real applications, we have established the full cells (for LIBs, MnS@C//LiFePO₄; for SIBs, MnS@C//Na₃V₂(PO₄)₃), both of which are capable of showing remarkable specific capacities, outstanding rate performance, and superb cyclic endurance. This work offers a scalable, simple, and efficient evolution method to produce the integrated hybrid of MnS@C NWs, providing useful inspiration/guidelines for anodic applications of metal sulfides in next-generation power sources.

Putting Nanoarmors on Yolk-Shell Si@C Nanoparticles: A Reliable Engineering Way To Build Better Si-Based Anodes for Li-Ion Batteries

Practical utilization of silicon (Si) for Li-ion batteries (LIBs) still remains sluggish because of its formidable kinetic problems of huge volume expansions over 300%, instable solid electrolyte interphase (SEI), and unsatisfactory electrical conductivity. Though using a yolk-shell (Y-S) Si@C nanodesign indeed helps to mitigate active changes, optimize SEI properties, and lower intrinsic charge-transfer impedances, the total anodic behaviors in reversibility, rate capabilities, and long-lasting cyclability are still far from perfect. To settle the above issues, we herein propose a reliable and effective way by putting tough and malleable Ni nanoarmors on Y-S Si@C nanoparticles (Si@C⊆Ni). The unique functionalized configurations endow such hybrid systems with superb reversible capacity retention (almost no capacity decay emerges in 600 cycles, retaining a reversible capacity beyond ∼1307 mA h g^-1), prominent cyclic stability, and rate behaviors. To justify their potential usage, full cells of (-)Si@C⊆Ni//LiFePO₄(+) are further constructed, delivering impressive specific energy and power densities (max.

VALUES

∼423 W h kg^-1/∼497.8 W kg^-1). This paradigm work may offer a highly feasible engineering protocol to push forward Si anode performances for next-generation LIBs.

The re-emergence of sodium ion batteries: testing, processing, and manufacturability

With the re-emergence of sodium ion batteries (NIBs), we discuss the reasons for the recent interests in this technology and discuss the synergies between lithium ion battery (LIB) and NIB technologies and the potential for NIB as a "drop-in" technology for LIB manufacturing. The electrochemical testing of sodium materials in sodium metal anode arrangements is reviewed. The performance, stability, and polarization of the sodium in these test cells lead to alternative testing in three-electrode and alternative anode cell configurations. NIB manufacturability is also discussed, together with the impact that the material stability has upon the electrodes and coating. Finally, full-cell NIB technologies are reviewed, and literature proof-of-concept cells give an idea of some of the key differences in the testing protocols of these batteries. For more commercially relevant formats, safety, passive voltage control through cell balancing and cell formation aspects are discussed.

Moving to Aqueous Binder: A Valid Approach to Achieving High-Rate Capability and Long-Term Durability for Sodium-Ion Battery

Polyanionic Na3V2(PO4)2F3 with a NASICON-type structure is heralded as a promising cathode material for sodium-ion batteries due to its fast ionic conduction, high working voltage, and favorable structural stability. However, a number of challenging issues remain regarding its rate capability and cycle life, which must be addressed to enable greater application compatibility. Here, a facile and effective approach that can be used to overcome these disadvantages by introducing an aqueous carboxymethyl cellulose (CMC) binder is reported. The resulting conductive network serves to accelerate the diffusion of Na+ ions across the interface as well as in the bulk. The strong binding force of the CMC and stable solid permeable interface protect the electrode from degradation, leading to an excellent capacity of 75 mA h g-1 at an ultrahigh rate of 70 C (1 C = 128 mA g-1) and a long lifespan of 3500 cycles at 30 C while sustaining 79% of the initial capacity value. A full cell based on this electrode material delivers an impressive energy density as high as 216 W h kg-1, indicating the potential for application of this straightforward and cost-effective route for the future development of advanced battery technologies.

A New Strategy to Stabilize Capacity and Insight into the Interface Behavior in Electrochemical Reaction of LiNi0.5Mn1.5O4/Graphite System for High-Voltage Lithium-Ion Batteries

The performance of CEI and SEI configuration and formation mechanism on the cathode and anode side for LiNi_0.5Mn_1.5O₄/natural graphite (LNMO/NG) batteries is investigated, where series permutations of the NG electrodes modified with TEOS species as the anode for the LNMO full cells. It is believed that the excellent long-term cycling performance of LNMO/NG full cells at the high voltage is a result of alleviating the devastated reaction to form the CEI and SEI on the both electrodes with electrolyte, respectively. At a voltage range from 3.4 to 4.8 V for the LNMO full cells, 95.0% capacity retention after 100 cycles is achieved when cycled with TEOS-modifying NG anode. This mechanism may be explained that eliminating the HF and absorbing water impurities in the electrolyte by introducing the TEOS group, which can transform the SiO₂ species that react with the acid of HF at the organic solvent environment instead of destroying/forming the anode SEI and attacking the LNMO spinel structure to form the dense and high resistance CEI, meanwhile the SiO₂ species will absorb the water molecule and precipitate into the anode surface further stabilizing the SEI configuration during the cycling.

Porous-Nickel-Scaffolded Tin-Antimony Anodes with Enhanced Electrochemical Properties for Li/Na-Ion Batteries

The energy and power densities of rechargeable batteries urgently need to be increased to meet the ever-increasing demands of consumer electronics and electric vehicles. Alloy anodes are among the most promising candidates for next-generation high-capacity battery materials. However, the high capacities of alloy anodes usually suffer from some serious difficulties related to the volume changes of active materials. Porous supports and nanostructured alloy materials have been explored to address these issues. However, these approaches seemingly increase the active material-based properties and actually decrease the electrode-based capacity because of the oversized pores and heavy mass of mechanical supports. In this study, we developed an ultralight porous nickel to scaffold with high-capacity SnSb alloy anodes. The porous-nickel-supported SnSb alloy demonstrates a high specific capacity and good cyclability for both Li-ion and Na-ion batteries. Its capacity retains 580 mA h g^-1 at 2 A g^-1 after 100 cycles in Li-ion batteries. For a Na-ion battery, the composite electrode can even deliver a capacity of 275 mA h g^-1 at 1 A g^-1 after 1000 cycles. This study demonstrates that combining the scaffolding function of ultralight porous nickel and the high capacity of the SnSb alloy can significantly enhance the electrochemical performances of Li/Na-ion batteries.

Emerging Prototype Sodium-Ion Full Cells with Nanostructured Electrode Materials

Due to steadily increasing energy consumption, the demand of renewable energy sources is more urgent than ever. Sodium-ion batteries (SIBs) have emerged as a cost-effective alternative because of the earth abundance of Na resources and their competitive electrochemical behaviors. Before practical application, it is essential to establish a bridge between the sodium half-cell and the commercial battery from a full cell perspective. An overview of the major challenges, most recent advances, and outlooks of non-aqueous and aqueous sodium-ion full cells (SIFCs) is presented. Considering the intimate relationship between SIFCs and electrode materials, including structure, composition and mutual matching principle, both the advance of various prototype SIFCs and the electrochemistry development of nanostructured electrode materials are reviewed. It is noted that a series of SIFCs combined with layered oxides and hard carbon are capable of providing a high specific gravimetric energy above 200 Wh kg^-1 , and an NaCrO₂ //hard carbon full cell is able to deliver a high rate capability over 100 C. To achieve industrialization of SIBs, more systematic work should focus on electrode construction, component compatibility, and battery technologies.

Long-Life Nickel-Rich Layered Oxide Cathodes with a Uniform Li2ZrO3 Surface Coating for Lithium-Ion Batteries

As nickel-rich layered oxide cathodes start to attract worldwide interest for the next-generation lithium-ion batteries, their long-term cyclability in full cells remains a challenge for electric vehicles. Here we report a long-life Ni-rich layered oxide cathode (LiNi_0.7Co_0.15Mn_0.15O₂) with a uniform surface coating of the cathode particles with Li₂ZrO₃. A pouch-type full cell fabricated with the Li₂ZrO₃-coated cathode and a graphite anode displays 73.3% capacity retention after 1500 cycles at a C/3 rate. The Li₂ZrO₃ coating has been optimized by a systematic study with different synthesis approaches, annealing temperatures, and coating amounts. The complex relationship among the coating conditions, uniformity, and morphology of the coating layer and their impacts on the electrochemical properties are discussed in detail.

Metal-Organic Framework-Derived NiSb Alloy Embedded in Carbon Hollow Spheres as Superior Lithium-Ion Battery Anodes

The MOFs (metal-organic frameworks) have been extensively used for electrode materials due to their high surface area, permanent porosity, and hollow structure, but the role of antimony on the MOFs is unclear. In this work, we design the hollow spheres Ni-MOFs with SbCl₃ to synthesize NiSb⊂CHSs (NiSb-embedded carbon hollow spheres) via simple annealing and galvanic replacement reactions. The NiSb⊂CHSs inherited the advantages of Ni-MOFs with hollow structure, high surface area, and permanent porosity, and the NiSb nanoparticles are coated by the formed carbon particles which could effectively solve the problem of vigorous volume changes during the Li⁺ insertion/extraction process. The porous and network structure could well provide an extremely reduced pathway for fast Li⁺ diffusion and electron transport and provide extra free space for alleviating the structural strain. The NiSb⊂CHSs with these features were used as Li-ion batteries for the first time and exhibited excellent cycling performance, high specific capacity, and great rate capability. When coupled with a nanostructure LiMn₂O₄ cathode, the NiSb⊂CHSs//LiMn₂O₄ full cell also characterized a high voltage operation of ≈3.5 V, high rate capability (210 mA h g^-1 at a current density of 2000 mA g^-1), and high Coulombic efficiency of approximate 99%, meeting the requirement for the increasing demand for improved energy devices.

One-Dimensional Yolk-Shell Sb@Ti-O-P Nanostructures as a High-Capacity and High-Rate Anode Material for Sodium Ion Batteries

Development of high energy/power density and long cycle life of anode materials is highly desirable for sodium ion batteries, because graphite anode cannot be used directly. Sb stands out from the potential candidates, due to high capacity, good electronic conductivity, and moderate sodiation voltage. Here, one-dimensional yolk-shell Sb@Ti-O-P nanostructures are synthesized by reducing core-shell Sb₂O₃@TiO₂ nanorods with NaH₂PO₂. This structure has Sb nanorod as the core to increase the capacity and Ti-O-P as the shell to stabilize the interface between electrolyte and electrode material. The gap between the core and the shell accommodates the volume change during sodiation/desodiation. These features endow the structure outstanding performances. It could deliver a capacity of about 760 mA h g^-1 after 200 cycles at 500 mA g^-1, with a capacity retention of about 94%. Even at 10 A g^-1, the reversible capacity is still at 360 mA h g^-1. The full battery of Sb@Ti-O-P//Na₃V₂(PO₄)₃-C presents a high output voltage (∼2.7 V) and a capacity of 392 mA h g^-1_anode after 150 cycles at 1 A g^-1_anode.

Fabrication of High-Energy Li-Ion Cells with Li4 Ti5 O12 Microspheres as Anode and 0.5 Li2 MnO3 ⋅0.5 LiNi0.4 Co0.2 Mn0.4 O2 Microspheres as Cathode

In this work, we propose an effective way to prepare nanosized Li4 Ti5 O12 (LTO) microspheres and 0.5 Li2 MnO3 ⋅0.5 LiNi0.4 Co0.2 Mn0.4 O2 (NCM) microspheres by similar spray-drying methods. Both obtained materials are accumulated by primary nanoparticles and show a spherical morphology with particle distribution of 10-20 μm. The LTO microspheres deliver a tap density of 1.04 g cm(-3) , while the tap density of NCM microspheres is 2.07 g cm(-3) , which means an enhanced volumetric energy density. The as-prepared LTO microspheres have a reversible capacity of 170 mA h g(-1) at 0.1 C and a capacity retention of 97 % after 250 cycles at 1 C. The NCM microspheres have an initial discharge capacity of 270 mA h g(-1) with a corresponding Coulombic efficiency of 88 % at 0.03 C. Both materials show a relatively good rate capability. The Li4 Ti5 O12 /0.5 Li2 MnO3 ⋅0.5 LiNi0.4 Co0.2 Mn0.4 O2 cells deliver a high cathode specific capacity of 273 mA h g(-1) and good initial Coulombic efficiency of 88 % at 0.03 C, and can be developed for powering hybrid and plug-in hybrid vehicles.

In Situ Binding Sb Nanospheres on Graphene via Oxygen Bonds as Superior Anode for Ultrafast Sodium-Ion Batteries

Graphene incorporation should be one effective strategy to develop advanced electrode materials for a sodium-ion battery (SIB). Herein, the micro/nanostructural Sb/graphene composite (Sb-O-G) is successfully prepared with the uniform Sb nanospheres (∼100 nm) bound on the graphene via oxygen bonds. It is revealed that the in-situ-constructed oxygen bonds play a significant role on enhancing Na-storage properties, especially the ultrafast charge/discharge capability. The oxygen-bond-enhanced Sb-O-G composite can deliver a high capacity of 220 mAh/g at an ultrahigh current density of 12 A/g, which is obviously superior to the similar Sb/G composite (130 mAh/g at 10 A/g) just without Sb-O-C bonds. It also exhibits the highest Na-storage capacity compared to Sb/G and pure Sb nanoparticles as well as the best cycling performance. More importantly, this Sb-O-G anode achieves ultrafast (120 C) energy storage in SIB full cells, which have already been shown to power a 26-bulb array and calculator. All of these superior performances originate from the structural stability of Sb-O-C bonds during Na uptake/release, which has been verified by ex situ X-ray photoelectron spectroscopies and infrared spectroscopies.

High-Capacity Te Anode Confined in Microporous Carbon for Long-Life Na-Ion Batteries

Sodium-ion batteries (SIBs) have attracted considerable attention as an alternative energy-storage technology in recent years. Developing advanced sodium storage anode materials with appropriate working potential, high capacity, and good cycling performance is very important. Herein, we demonstrate a nanostructured tellurium@carbon (nano-Te@C) composite by confining nano-Te molecules in the space of carbon micropores as an attractive anode material for SIBs. The nano-Te@C anode presents an appropriate redox potential in the range of 1.05-1.35 V (vs Na(+)/Na), which avoids the Na dendrite problem and achieves a high reversible capacity of 410 mA h g(-1) on the basis of a two-electron redox reaction mechanism. Notably, the nano-Te@C exhibits an admirable long-term cycling stability with a high capacity retention of 90% for 1000 cycles (i.e., ultralow capacity decay of 0.01% per cycle). The excellent electrochemical property of nano-Te@C benefits from the high electroactivity from the nanostructure design and the effective confinement of the microporous carbon host. In addition, a Na-ion full cell by using nano-Te@C as anode and Na2/3Ni1/3Mn2/3O2 as cathode is demonstrated for the first time and exhibits a remarkable capacity retention up to 95% after 150 cycles. The results put new insights for the development of advanced SIBs with long-cycle lifespan.