Sn-Based Nanocomposite for Li-Ion Battery Anode with High Energy Density, Rate Capability, and Reversibility

Heterostructured Mn-Sn Bimetallic Sulfide Nanocubes Confined in N, S-co-Doped Carbon Framework as High-Performance Anodes for Sodium-Ion Batteries

Benefiting from its high theoretical capacity, tin disulfide (SnS2) draws abundant interest and attention for its promising practical prospect for sodium-ion batteries (SIBs). However, the huge volumetric variation in sodiation/desodiation reactions usually results in the fast decay of rate and cycling properties, which seriously obstructs its future applicable foregrounds. Herein, heterostructured Mn-Sn bimetallic sulfide nanocubes confined in N and S-codoped carbon (MSS@NSC) were rationally designed via a facile coprecipitation followed by a sulfurization strategy. When used as anodes for SIBs, the heterojunctions at the interfaces effectively accelerate the Na+ diffusion rate to promote the sodium-storage reaction kinetics. The N and S-codoped carbon provides a rapid conductive framework for the fast charge transport during the sodium-storage process. Moreover, the beneficial confinement effect of the NSC layer effectively guarantees a superb cycle property for the MSS@NSC anode. The favorable synergistic effects between the highly conductive framework of the NSC and MSS heterostructure endow the MSS@NSC anode with satisfactory electrochemical Na-storage properties.

Tailoring of High-Valent Sn-Doped Porous Na3V2(PO4)3/C Nanoarchitechtonics: An Ultra High-Rate Cathode for Sodium-Ion Batteries

NASICON structured Na3V2(PO4)3 (NVP) has captured enormous attention as a potential cathode for next-generation sodium-ion batteries (SIBs), owing to its sturdy crystal structure and high theoretical capacity. Nonetheless, its poor intrinsic electronic conductivity has led to inferior electrochemical performance in terms of rate capability and long cycling performance. To address this problem, a combined strategy is adopted, such as (1) carbon coating and (2) high valent Sn4+ ion doping in the lattice site of vanadium in the NVP cathode. Carbon coating can effectively enhance the surface electronic conductivity, wherein high-valent Sn4+ improves the bulk intrinsic electronic conductivity of the materials. Moreover, Sn is a well-known alloying/dealloying type anode for SIBs; thus, doping of such metal in cathode materials will assume the role of structure stabilizing pillars and establishing high-performing cathode materials. Herein, Na3V2-xSnx(PO4)3/C (denoted as Sn(x)-NVP/C, where x = 0.00, 0.03, 0.05, 0.07, 0.1) were synthesized via sol-gel route, followed by calcination at 800 °C. XRD, Raman, XPS, and electron microscopy data confirmed the high purity of the synthesized cathode. The optimized Sn(0.07)-NVP/C exhibited excellent electrochemical performance in terms of high rate capability and long cycling performance, a high appreciable capacity of 98 mAh g-1 with capacity retention of 85% after 500 cycles. Similarly, at a high current of 20C, it is still able to deliver a stable capacity of 76 mAh g-1 with 85% capacity retention after 3000 cycles. The rate capability study indicates the high current tolerance of Sn(0.07)-NVP/C up to 70 C with a capacity delivery of 55 mAh g-1. It is worth mentioning that CV and EIS analysis for Sn(0.07)-NVP/C cathode displayed minimum voltage polarization and enhanced diffusion coefficient. Moreover, DFT calculation also proved that the electronic and ionic conductivity of NVP is promoted by Sn doping. Hence, the present results demonstrated that Sn(0.07)-NVP/C is considered a promising cathode for sodium-ion battery application.

Cathode materials for lithium-sulfur battery: a review

Lithium-sulfur batteries (LSBs) are considered to be one of the most promising candidates for becoming the post-lithium-ion battery technology, which would require a high level of energy density across a variety of applications. An increasing amount of research has been conducted on LSBs over the past decade to develop fundamental understanding, modelling, and application-based control. In this study, the advantages and disadvantages of LSB technology are discussed from a fundamental perspective. Then, the focus shifts to intermediate lithium polysulfide adsorption capacity and the challenges involved in improving LSBs by using alternative materials besides carbon for cathode construction. Attempted alternative materials include metal oxides, metal carbides, metal nitrides, MXenes, graphene, quantum dots, and metal organic frameworks. One critical issue is that polar material should be more favorable than non-polar carbonaceous materials in the aspect of intermediate lithium polysulfide species adsorption and suppress shuttle effect. It will be also presented that by preparing cathode with suitable materials and morphological structure, high-performance LSB can be obtained.

Graphical abstract

Low-Dimensional Nanomaterial Systems Formed by IVA Group Elements Allow Energy Conversion Materials to Flourish

In response to the exhaustion of traditional energy, green and efficient energy conversion has attracted growing attention. The IVA group elements, especially carbon, are widely distributed and stable in the earth’s crust, and have received a lot of attention from scientists. The low-dimensional structures composed of IVA group elements have special energy band structure and electrical properties, which allow them to show more excellent performance in the fields of energy conversion. In recent years, the diversification of synthesis and optimization of properties of IVA group elements low-dimensional nanomaterials (IVA-LD) contributed to the flourishing development of related fields. This paper reviews the properties and synthesis methods of IVA-LD for energy conversion devices, as well as their current applications in major fields such as ion battery, moisture electricity generation, and solar-driven evaporation. Finally, the prospects and challenges faced by the IVA-LD in the field of energy conversion are discussed.

Metaphosphate-Bridged Interface Boosts High-Performance Lithium Storage

Carbon materials with well-dispersed SnO_x particles exhibit excellent lithium-storage performance. However, the volume change of SnO_x and the weak interaction between SnO_x and carbon induce an unsteady SnO_x-C interface during the lithiation/delithiation process. This phenomenon results in enhanced charge transfer resistance and reduced electrical contact of active materials, which leads to low reversibility of tin oxidation, restricted capacity, sluggish kinetics, structural deterioration, and rapid capacity decay. Herein, tin oxide/carbon composites with a metaphosphate-bridged interface are synthesized to construct a robust interfacial contact between tin oxides and carbon. The metaphosphate group functions as a bridge between SnO_x and carbon and results in excellent electrochemical stability during the charge/discharge process, which is favorable for electrode structural integrity. The formation of the metaphosphate-bridged interface provides a steady transport channel for e^-/Li⁺ and thus improves the reversibility of the conversion reaction. The enhanced charge transfer and interaction can also boost the charge transfer between SnO_x and carbon, which leads to higher SnO_x utilization. Thus, the prepared P-SnO_x/C anode exhibits enhanced lithium-storage performance in terms of specific capacity, cycling stability, and rate performance.

Optimizing SnO2- x /Fe2 O3 Hetero-Nanocrystals Toward Rapid and Highly Reversible Lithium Storage

Engineering oxygen vacancy and boosting Li₂ O reversibility on oxides-based electrode are of significance but remains a challenge in high-power lithium-ion batteries. Herein, the heterogenous SnO_{2- x} /Fe₂ O_{3- y} nanocrystals are demonstrated with tailorable x and y values enabled by a glucose-assisted spray combustion technique. Density functional theory calculations unveil the SnO_{2- x} /Fe₂ O₃ with a maximum x value has the optimal electronic structure, the metallic Fe generated from Fe₂ O₃ can markedly reduce the free energy to break Li-O bonds for accelerating subsequent delithiation process of Li₂ O. Consequently, the optimized SnO_{2- x} /Fe₂ O₃ exhibits a remarkably enhanced electrochemical reversibility and reaction kinetics. After stabilized by reduced graphene oxide, the hybrid delivers a high reversible specific capacity of 1113 mAh g^-1 with superior rate performance (474 mAh g^-1 at 20 A g^-1 ) and long cycle life (negligible loss after 500 cycles at 5 A g^-1 ), the oxygen vacancy and microstructure are well-maintained after cycles. This work provides the possibilities for skillfully regulating oxygen vacancy and meantime enhancing Li₂ O reversibility.

Versatile Interfacial Self-Assembly of Ti3C2Tx MXene Based Composites with Enhanced Kinetics for Superior Lithium and Sodium Storage

Exploring nanostructured transition-metal sulfide anode materials with excellent electrical conductivity is the key point for high-performance alkali metal ion storage devices. Herein, we propose a powerful bottom-up strategy for the construction of a series of sandwich-structured materials by a rapid interfacial self-assembly approach. Oleylamine could act as a functional reagent to guarantee that the nanomaterials self-assemble with MXene. Benefiting from the small size of Co-NiS nanorods, excellent conductivity of MXene, and sandwiched structure of the composite, the Co-NiS/MXene composite could deliver a high discharge capacity of 911 mAh g^-1 at 0.1 A g^-1 for lithium-ion storage. After 200 cycles at 0.1 A g^-1, a high specific capacity of 1120 mAh g^-1 could be still remaining, indicating excellent cycling stability. For sodium-ion storage, the composite exhibits high specific capacity of 541 mAh g^-1 at 0.1 A g^-1 and excellent rate capability (263 mAh g^-1 at 5 A g^-1). This work offers a straightforward strategy to design and construct MXene-based anode nanomaterials with sandwiched structure for high-performance alkali metal ion storage and even in other fields.

SnO x /graphene anode material with multiple oxidation states for high-performance Li-ion batteries

Tin and its oxides are promising anode materials owing to their high theoretical capacity, rich resource, and environmental benignity. To achieve low cost and green synthesis, a facile synthetic route of SnO _x /graphene composites is proposed, using a simple galvanic replacement method to quickly obtain abundant foamed tin as raw material and ball milling method to realize a mechanochemical reaction between SnO _x (0 ≤ x ≤ 2) and graphene. Under different annealing conditions, the foamed tin is converted to tin oxides with multiple oxidation states (Sn₃O₄, SnO, and SnO₂). These unique components can greatly affect the electrochemical performance of the electrode in LIBs. The as-prepared electrode (SnO _x -300/G) obtained by annealing foamed tin at 300 °C for 4 h and combining SnO _x powders with graphene via ball milling shows great cycling stability, retaining a high capacity of 786 mA h g^-1 at 0.1 A g^-1 after 150 cycles, and its initial Coulombic efficiency can reach 84.03%. Thus, this facile synthesis can provide an environmentally friendly route for commercial production of high-performance energy storage materials.

Stoichiometry Dependence of Physical and Electrochemical Properties of the SnOx Film Anodes Deposited by Pulse DC Magnetron Sputtering

A batch of Sn oxides was fabricated by pulse direct current reactive magnetron sputtering (pDC-RMS) using different Ar/O₂ flow ratios at 0.3 Pa; the influence of stoichiometry on the physical and electrochemical properties of the films was evaluated by the characterization of scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray reflection (XRR), X-ray photoelectron spectroscopy (XPS) and more. The results were as follows. First, the film surface transitioned from a particle morphology (roughness of 50.0 nm) to a smooth state (roughness of 3.7 nm) when Ar/O₂ flow ratios changed from 30/0 to 23/7; second, all SnO_x films were in an amorphous state, some samples deposited with low O₂ flow ratios (≤2 sccm) still included metallic Sn grains. Therefore, the stoichiometry of SnO_x calculated by XPS spectra increased linearly from SnO_0.0.08 to SnO_1.71 as the O₂ flow ratios increased, and the oxidation degree was further calibrated by the average valence method and SnO₂ standard material. Finally, the electrochemical performance was confirmed to be improved with the increase in oxidation degree (x) in SnO_x, and the SnO_1.71 film deposited with Ar/O₂ = 23/7 possessed the best cycle performance, reversible capacity of 396.1 mAh/g and a capacity retention ratio of 75.4% after 50 cycles at a constant current density of 44 μA/cm².

Dual Buffering Inverse Design of Three-Dimensional Graphene-Supported Sn-TiO2 Anodes for Durable Lithium-Ion Batteries

Stable battery operation involving high-capacity electrode materials such as tin (Sn) has been plagued by dimensional instability-driven battery degradation despite the potentially accessible high energy density of batteries. Rational design of Sn-based electrodes inevitably requires buffering or passivation layers mostly in a multi-stacked manner with sufficient void inside the shells. However, undesirable void engineering incurs energy loss and shell fracture during the strong calendaring process. Here, this study reports an inverse design of freestanding 3D graphene electrodes sequentially passivated by capacity-contributing Sn and protective/buffering TiO₂ . Monodisperse polymer bead templates coated with inner TiO₂ and outer SnO₂ layers generate regular macropores and 3D interconnected graphene framework while the inner TiO₂ shell turns inside out to fully passivate the surface of Sn nanoparticles during the thermal annealing process. The prepared 3D freestanding electrodes are simultaneously buffered by electronically conductive and flexible graphene support and ion-permeable/mechanically stable TiO₂ nanoshells, thus greatly extending the cycle life of batteries more than 5000 cycles at 5 C with a reversible capacity of ≈520 mAh g^-1 with a high volumetric energy density.

Stabilization of Sn Anode through Structural Reconstruction of a Cu-Sn Intermetallic Coating Layer

The metallic tin (Sn) anode is a promising candidate for next-generation lithium-ion batteries (LIBs) due to its high theoretical capacity and electrical conductivity. However, Sn suffers from severe mechanical degradation caused by large volume changes during lithiation/delithiation, which leads to a rapid capacity decay for LIBs application. Herein, a Cu-Sn (e.g., Cu₃ Sn) intermetallic coating layer (ICL) is rationally designed to stabilize Sn through a structural reconstruction mechanism. The low activity of the Cu-Sn ICL against lithiation/delithiation enables the gradual separation of the metallic Cu phase from the Cu-Sn ICL, which provides a regulatable and appropriate distribution of Cu to buffer volume change of Sn anode. Concurrently, the homogeneous distribution of the separated Sn together with Cu promotes uniform lithiation/delithiation, mitigating the internal stress. In addition, the residual rigid Cu-Sn intermetallic shows terrific mechanical integrity that resists the plastic deformation during the lithiation/delithiation. As a result, the Sn anode enhanced by the Cu-Sn ICL shows a significant improvement in cycling stability with a dramatically reduced capacity decay rate of 0.03% per cycle for 1000 cycles. The structural reconstruction mechanism in this work shines a light on new materials and structural design that can stabilize high-performance and high-volume-change electrodes for rechargeable batteries and beyond.

Zinc Phosphides as Outstanding Sodium-Ion Battery Anodes

To design a high-performance sodium-ion battery anode, binary zinc phosphides (ZnP₂ and Zn₃P₂) were synthesized by a facile solid-state heat treatment process, and their Na storage characteristics were evaluated. The Na reactivity of ZnP₂ was better than that of Zn₃P₂. Therefore, a C-modified ZnP₂-based composite (ZnP₂-C) was fabricated to achieve better electrochemical performance. To investigate the electrochemical reaction mechanism of ZnP₂-C during sodiation/desodiation, various ex situ analytical techniques were employed. During sodiation, ZnP₂ in the composite was transformed into NaZn₁₃ and Na₃P phases, exhibiting a one-step conversion reaction. Conversely, Zn and P in NaZn₁₃ and Na₃P, respectively, were fully recombined to the original ZnP₂ phase during desodiation. Owing to the one-step conversion/recombination of ZnP₂ in the composite during cycling, the ZnP₂-C showed high electrochemical performance with a highly reversible capacity of 883 mA h g^-1 after 130 cycles with no capacity deterioration and a fast C-rate capability of 500 mA h g^-1 at 1 C and 350 mA h g^-1 at 3 C.

Tin and Tin Compound Materials as Anodes in Lithium-Ion and Sodium-Ion Batteries: A Review

Tin and tin compounds are perceived as promising next-generation lithium (sodium)-ion batteries anodes because of their high theoretical capacity, low cost and proper working potentials. However, their practical applications are severely hampered by huge volume changes during Li⁺ (Na⁺) insertion and extraction processes, which could lead to a vast irreversible capacity loss and short cycle life. The significance of morphology design and synergic effects-through combining compatible compounds and/or metals together-on electrochemical properties are analyzed to circumvent these problems. In this review, recent progress and understanding of tin and tin compounds used in lithium (sodium)-ion batteries have been summarized and related approaches to optimize electrochemical performance are also pointed out. Superiorities and intrinsic flaws of the above-mentioned materials that can affect electrochemical performance are discussed, aiming to provide a comprehensive understanding of tin and tin compounds in lithium(sodium)-ion batteries.

Monodisperse CoSn and NiSn Nanoparticles Supported on Commercial Carbon as Anode for Lithium- and Potassium-Ion Batteries

Monodisperse CoSn and NiSn nanoparticles were prepared in solution and supported on commercial carbon black. The obtained nanocomposites were applied as anodes for Li- and K-ion batteries. CoSn@C delivered stable average capacities of 850, 650, and 500 mAh g^-1 at 0.2, 1.0, and 2.0 A g^-1, respectively, well above those of commercial graphite anodes. The capacity of NiSn@C retained up to 575 mAh g^-1 at a current of 1.0 A g^-1 over 200 continuous cycles. Up to 74.5 and 69.7% pseudocapacitance contributions for Li-ion batteries were measured for CoSn@C and NiSn@C, respectively, at 1.0 mV s^-1. CoSn@C was further tested in full-cell lithium-ion batteries with a LiFePO₄ cathode to yield a stable capacity of 350 mAh g^-1 at a rate of 0.2 A g^-1. As electrode in K-ion batteries, CoSn@C composites presented a stable capacity of around 200 mAh g^-1 at 0.2 A g^-1 over 400 continuous cycles, and NiSn@C delivered a lower capacity of around 100 mAh g^-1 over 300 cycles.

Cobalt-doping SnS2 nanosheets towards high-performance anodes for sodium ion batteries

Layered SnS₂ is considered as a promising anode candidate for sodium-ion batteries yet suffers from low initial coulombic efficiency, limited specific capacity and rate capability. Herein, we report a cobalt metal cation doping strategy to enhance the electrochemical performance of a SnS₂ nanosheet array anode through a facile hydrothermal method. Benefitting from this special structure and heteroatom-doping effect, this anode material displays a high initial coulombic efficiency of 57.4%, a superior discharge specific capacity as high as 1288 mA h g^-1 at 0.2 A g^-1 after 100 cycles and outstanding long-term cycling stability with a reversible capacity of 800.4 mA h g^-1 even at 2 A g^-1. These excellent performances could be ascribed to the Co-doping effect that can increase the interlayer spacing, produce rich defects, regulate the electronic environment and improve conductivity. Besides, a carbon cloth substrate can maintain the integrity of the electrode material framework and buffer its volume variation, thus boosting intrinsic dynamic properties and enhancing sodium storage performance.

Convenient fabrication of a core–shell Sn@TiO2 anode for lithium storage from tinplate electroplating sludge

A convenient route was developed for the fabrication of a high-performance core–shell Sn@TiO₂ anode for LIBs from tinplate electroplating sludge.

Enhancement Effects of Co Doping on Interfacial Properties of Sn Electrode-Collector: A First-Principles Study

The Co doping effects on the interfacial strength of Sn electrode-collector interface for lithium-ion batteries are investigated by using first-principles calculations. The results demonstrate that by forming strong chemical bonds with interfacial Sn, Li, and Cu atoms, Co doping in the interface region can enhance interfacial strengths and stabilities during lithiation. With doping, the highest strengths of Sn/Cu (1.74 J m^-2) and LiSn/Cu (1.73 J m^-2) interfaces are 9.4 and 17.7% higher than those of the corresponding interface systems before doping. Besides, Co doping can reduce interface charge accumulation and offset the decreasing interfacial strength during lithiation. Furthermore, the interfacial strength and electronic stability increase with rising Co content, whereas the increasing formation heat may result in thermodynamic instability. On the basis of the change of formation heat with Co content, an optimal Co doping content has been provided.

Phase Dynamics on Conversion-Reaction-Based Tin-Doped Ferrite Anode for Next-Generation Lithium Batteries

The conventional view of conversion reaction is based on the reversibility, returning to an initial material structure through reverse reaction at each cycle in cycle life, which impedes the complete understanding on a working mechanism upon a progression of cycles in conversion-reaction-based battery electrodes. Herein, a series of tin-doped ferrites (Fe_{3- x}Sn _xO₄, x = 0-0.36) are prepared and applied to a lithium-ion battery anode. By achieving the ideal reoxidation into SnO₂, the Fe_2.76Sn_0.24O₄ composite anchored on reduced graphene oxide shows a high reversible capacity of 1428 mAh g^-1 at 200 mA g^-1 after 100 cycles, which is the best performance of Sn-based anode materials so far. Significantly, a newly formed γ-FeOOH phase after 100 cycles is identified from topological features through synchrotron X-ray absorption spectroscopy with electronic and atomic structural information, suggesting the phase transformation from magnetite to lepidocrocite upon cycling. Contrary to the conventional view, our work suggests a variable working mechanism in an iron-based composite with the dynamic phases from iron oxide to iron oxyhydroxide in the battery cycle life, based on the reactivity of metal nanoparticles formed during reaction toward the solid electrolyte interface layer.

Fabrication of SnS2/Mn2SnS4/Carbon Heterostructures for Sodium-Ion Batteries with High Initial Coulombic Efficiency and Cycling Stability

SnS₂ has been extensive studied as an anode material for sodium storage owing to its high theoretical specific capacity, whereas the unsatisfied initial Coulombic efficiency (ICE) caused by the partial irreversible conversion reaction during the charge/discharge process is one of the critical issues that hamper its practical applications. Hence, heterostructured SnS₂/Mn₂SnS₄/carbon nanoboxes (SMS/C NBs) have been developed by a facial wet-chemical method and utilized as the anode material of sodium ion batteries. SMS/C NBs can deliver an initial capacity of 841.2 mAh g^-1 with high ICE of 90.8%, excellent rate capability (752.3, 604.7, 570.1, 546.9, 519.7, and 488.7 mAh g^-1 at the current rate of 0.1, 0.5, 1.0, 2.0, 5.0, and 10.0 A g^-1, respectively), and long cycling stability (522.5 mAh g^-1 at 5.0 A g^-1 after 500 cycles). The existence of SnS₂/Mn₂SnS₄ heterojunctions can effectively stabilize the reaction products Sn and Na₂S, greatly prevent the coarsening of nanosized Sn⁰, and enhance reversible conversion--alloying reaction, which play a key role in improving the ICE and extending the cycling performance. Moreover, the heterostructured SMS coupled with the interacting carbon network provides efficient channels for electrons and Na⁺ diffusion, resulting in an excellent rate performance.

A bee pupa-infilled honeycomb structure-inspired Li2MnSiO4 cathode for high volumetric energy density secondary batteries

Emerging power batteries with both high volumetric energy density and fast charge/discharge kinetics are required for electric vehicles. The rapid ion/electron transport of mesostructured electrodes enables a high electrochemical activity in secondary batteries. However, the typical low fraction of active materials leads to a low volumetric energy density. Herein, we report a novel biomimetic "bee pupa infilled honeycomb"-structured 3D mesoporous cathode. We found previously the maximum active material filing fraction of an opal template before pinch-off was about 25%, whereas it could be increased to ∼90% with the bee pupa-infilled honeycomb-like architecture. Importantly, even with a high infilling fraction, fast Li+/e- transport kinetics and robust mechanical property were achievable. As the demonstration, a bee pupa infilled honeycomb-shaped Li2MnSiO4/C cathode was constructed, which delivered a high volumetric energy density of 2443 W h L-1. The presented biomimetic bee pupa infilled honeycomb configuration is applicable for a broad set of both cathodes and anodes in high energy density batteries.

Tin nanoparticles embedded in an N-doped microporous carbon matrix derived from ZIF-8 as an anode for ultralong-life and ultrahigh-rate lithium-ion batteries

A carbon matrix with abundant micropores derived from ZIF-8 can confine Sn particles in an ultrasmall nanosize, contributing to the buffering of the huge volume changes.

An all-in-one Sn–Co alloy as a binder-free anode for high-capacity batteries and its dynamic lithiation in situ

An all-in-one Sn–Co alloy anode is reported, which exhibits a robust electrode structure confirmed by in situ transmission electron microscopy.

Tip-Sonicated Red Phosphorus-Graphene Nanoribbon Composite for Full Lithium-Ion Batteries

Red phosphorus (RP) is considered a promising anode material for lithium-ion batteries (LIBs) due to its high energy density and low cost. Although RP is electrically insulating, researchers have reduced its particle size and added conductive fillers to improve the electrochemical activity of RP. Here, we report a method for making <1 μm sized RP under ambient conditions by using tip sonication. A specific surfactant solution was used to stabilize the dispersion of <1 μm sized RP. Graphene nanoribbons (GNRs) were added to improve the conductivity. The RP-GNR composite achieved nearly maximum capacity at 0.1C and showed a capacity retention of 96% after 216 cycles at 0.4 C in the half-cell. When combined with a LiCoO₂ cathode, the full cell delivered a total capacity of 86 mAh/g after 200 cycles at 0.4C. This study has demonstrated the fabrication of high-performance LIBs using RP in a safe, convenient, and cost-effective manner, and the method might be extended for the preparation of other battery or catalyst materials that are difficult to acquire through bottom-up or top-down approaches.

Low Interface Energies Tune the Electrochemical Reversibility of Tin Oxide Composite Nanoframes as Lithium-Ion Battery Anodes

The conversion reaction of lithia can push up the capacity limit of tin oxide-based anodes. However, the poor reversibility limits the practical applications of lithia in lithium-ion batteries. The latest reports indicate that the reversibility of lithia has been appropriately promoted by compositing tin oxide with transition metals. The underlying mechanism is not revealed. To design better anodes, we studied the nanostructured metal/Li₂O interfaces through atomic-scale modeling and proposed a porous nanoframe structure of Mn/Sn binary oxides. The first-principles calculation implied that because of a low interface energy of metal/Li₂O, Mn forms smaller particles in lithia than Sn. Ultrafine Mn nanoparticles surround Sn and suppress the coarsening of Sn particles. Such a composite design and the resultant interfaces significantly enhance the reversible Li-ion storage capabilities of tin oxides. The synthesized nanoframes of manganese tin oxides exhibit an initial capacity of 1620.6 mA h g^-1 at 0.05 A g^-1. Even after 1000 cycles, the nanoframe anode could deliver a capacity of 547.3 mA h g^-1 at 2 A g^-1. In general, we demonstrated a strategy of nanostructuring interfaces with low interface energy to enhance the Li-ion storage capability of binary tin oxides and revealed the mechanism of property enhancement, which might be applied to analyze other tin oxide composites.

Construction of 3D architectures with Ni(HCO3)2 nanocubes wrapped by reduced graphene oxide for LIBs: ultrahigh capacity, ultrafast rate capability and ultralong cycle stability

A 3D layered Ni(HCO₃)₂/rGO nano-architecture was fabricated by coordination self-assembly for high performance storage of Li-ions with fast electrode kinetics and a super-long life.

Rechargeable lithium-ion batteries (LIBs) have been the dominating technology for electric vehicles (EV) and grid storage in the current era, but they are still extensively demanded to further improve energy density, power density, and cycle life. Herein, a novel 3D layered nanoarchitecture network of Ni(HCO₃)₂/rGO composites with highly uniform Ni(HCO₃)₂ nanocubes (average diameter of 100 ± 20 nm) wrapped in rGO films is facilely fabricated by a one-step hydrothermal self-assembly process based on the electrostatic interaction and coordination principle. Benefiting from the synergistic effects, the Ni(HCO₃)₂/rGO electrode delivers an ultrahigh capacity (2450 mA h g^–1 at 0.1 A g^–1), ultrafast rate capability and ultralong cycling stability (1535 mA h g^–1 for the 1000^th cycle at 5 A g^–1, 803 mA h g^–1 for the 2000^th cycle at 10 A g^–1). The detailed electrochemical reaction mechanism investigated by in situ XRD further indicates that the 3D architecture of Ni(HCO₃)₂/rGO not only provides a good conductivity network and has a confinement effect on the rGO films, but also benefits from the reversible transfer from LiHCO₃ to Li_xC₂ (x = 0–2), further oxidation of nickel, and the formation of a stable/durable solid electrolyte interface (SEI) film (LiF and LiOH), which are responsible for the excellent storage performance of the Li-ions. This work could shed light on the design of high-capacity and low-cost anode materials for high energy storage in LIBs to meet the critical demands of EV and mobile information technology devices.