Core-Shell Co2VO4/Carbon Composite Anode for Highly Stable and Fast-Charging Sodium-Ion Batteries

Reduced Graphene Oxide-Supported SrV4O9 Microflowers with Enhanced Electrochemical Performance for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have received considerable attention in recent years. Anode material is one of the key factors that determine SIBs' electrochemical performance. Current commercial hard carbon anode shows poor rate performance, which greatly limits applications of SIBs. In this study, a novel vanadium-based material, SrV4O9, was proposed as an anode for SIBs, and its Na+ storage properties were studied for the first time. To enhance the electrical conductivity of SrV4O9 material, a microflower structure was designed and reduced graphene oxide (rGO) was introduced as a host to support SrV4O9 microflowers. The microflower structure effectively reduced electron diffusion distance, thus enhancing the electrical conductivity of the SrV4O9 material. The rGO showed excellent flexibility and electrical conductivity, which effectively improved the cycling life and rate performance of the SrV4O9 composite material. As a result, the SrV4O9@rGO composite showed excellent electrochemical performance (a stable capacity of 273.4 mAh g-1 after 200 cycles at 0.2 A g-1 and a high capacity of 120.4 mAh g-1 at 10.0 A g-1), indicating that SrV4O9@rGO composite can be an ideal anode material for SIBs.

Progress and Prospect of Bimetallic Oxides for Sodium-Ion Batteries: Synthesis, Mechanism, and Optimization Strategy

Sodium-ion batteries (SIBs) are considered as an alternative to and even replacement of lithium-ion batteries in the near future in order to address the energy crisis and scarcity of lithium resources due to the wide distribution and abundance of sodium resources on the earth. The exploration and development of high-performance anode materials are critical to the practical applications of advanced SIBs. Among various anode materials, bimetallic oxides (BMOs) have attracted special research attention because of their abundance, easy access, rich redox reactions, enhanced capacity and satisfactory cycling stability. Although many BMO anode materials have been reported as anode materials in SIBs, very limited studies summarized the progress and prospect of BMOs in practical applications of SIBs. In this review, recent progress and challenges of BMO anode materials for SIBs have been comprehensively summarized and discussed. First, the preparation methods and sodium storage mechanisms of BMOs are discussed. Then, the challenges, optimization strategies, and sodium storage performance of BMO anode materials have been reviewed and summarized. Finally, the prospects and future research directions of BMOs in SIBs have been proposed. This review aims to provide insight into the efficient design and optimization of BMO anode materials for high-performance SIBs.

MnCO3 Cuboids from Spent LIBs: A New Age Displacement Anode to Build High-Performance Li-Ion Capacitors

The advantage of hybridizing battery and supercapacitor electrodes has succeeded recently in designing hybrid charge storage systems such as lithium-ion capacitors (LICs) with the benefits of higher energy than supercapacitors and more power density than batteries. However, sluggish Li-ion diffusion of battery anode is one of the main barriers and hampers the development of high-performance LICs. Herein, is introduced a new conversion/displacement type anode, MnCO₃ , via effectively recycling spent Li-ion batteries cathodes for LICs applications. The MnCO₃  cuboids are regenerated from the spent LiMn₂ O₄  cathodes by organic acid lixiviation process, and hydrothermal treatment displays excellent reversibility of 535  mAh g^-1  after 50  cycles with a Coulombic efficiency of >99%. Later, LIC is assembled with the regenerated MnCO₃  cubes in pre-lithiated form (Mn⁰  + Li₂ CO₃ ) as anode and commercial activated carbon (AC) as the cathode, delivering a maximum energy density of 169.4 Wh kg^-1  at 25 °C with ultra-long durability of 15,000 cycles. Even at various atmospheres like -5 and 50 °C, this LIC can offer a energy densities of 53.8 and 119.5 Wh kg^-1 , respectively. Remarkably, the constructed AC/Mn⁰  + Li₂ CO₃ -based LIC exhibits a good cycling performance for a continuous 1000 cycles with >91% retention invariably for all temperature conditions.

Nitrogen-Doped and Sulfonated Carbon Dots as a Multifunctional Additive to Realize Highly Reversible Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) using the Zn metal anode have been considered as one of the next-generation commercial batteries with high security, robust capacity, and low price. However, parasitic reactions, notorious dendrites and limited lifespan still hamper their practical applications. Herein, an eco-friendly nitrogen-doped and sulfonated carbon dots (NSCDs) is designed as a multifunctional additive for the cheap aqueous ZnSO₄ electrolyte, which can overcome the above difficulties effectively. The abundant polar groups (-COOH, -OH, -NH₂ , and -SO₃ H) on the CDs surfaces can regulate the solvation structure of Zn²⁺ through decreasing the coordinated active H₂ O molecules, and thus redistribute Zn²⁺ deposition to avoid side reactions. Some of the negatively charged NSCDs are adsorbed on Zn anode surface to isolate the H₂ O/SO₄ ^2- corrosion through the electrostatic shielding effect. The synergistic effect of the doped nitrogen species and the surface sulfonic groups can induce a uniform electrolyte flux and a homogeneous Zn plating with a (002) texture. As a result, the excellent cycle life (4000 h) and Coulombic efficiency (99.5%) of the optimized ZIBs are realized in typical ZnSO₄ electrolytes with only 0.1 mg mL^-1 of NSCDs additive.

Recent Advances of ZnCo2 O4 -based Anode Materials for Li-ion Batteries

ZnCo₂ O₄ has been attracted wide research attention as a promising anode material for lithium-ion batteries (LIBs) in recent years based on its high theoretical specific capacity, low toxicity as well as stable chemical properties. However, the further large-scale application of pristine ZnCo₂ O₄ anode have been impeded because of its undesirable Li⁺ ion conductivity, low electronic conductivity, and finite stability of electrolytes at high potentials. Recently, optimizing the micro/nano structure, modification with carbonaceous materials, incorporation with metal oxides and constructing a binder-free structure on conductive substrate for ZnCo₂ O₄ -based materials have been verified as promising effective routes for solving the above problems. In this review, the recent advances in underlying reaction mechanisms, synthetic methods and strategies for improving the performance of ZnCo₂ O₄ anodes are comprehensively summarized. The factors affecting the electrochemical properties of ZnCo₂ O₄ -based materials are mainly discussed, and paths to promote the specific capacity and cyclic stability are proposed. Finally, several insights into the future developments, challenges, and prospects of ZnCo₂ O₄ -based anode materials of LIBs are proposed.

Investigation of Transport Mechanism and Nanostructure of Nylon-6,6/PVA Blend Polymers

A casting technique was used to prepare poly(vinyl alcohol) (PVA) blend polymers with different concentrations of Nylon-6,6 to increase the free-volume size and control the ionic conductivity of the blended polymers. The thermal activation energy for some blends is lower than that of pure polymers, indicating that their thermal stability is somewhere in between that of pure Nylon-6,6 and pure PVA. The degree of crystallinity of the blend sample (25.7%) was lower than that of the pure components (41.0 and 31.6% for pure Nylon-6,6 and PVA, respectively). The dielectric properties of the blended samples were investigated for different frequencies (50 Hz-5 MHz). The σ_ac versus frequency was found to obey Jonscher's universal power law. The calculated values of the s parameter were increased from 0.53 to 0.783 for 0 and 100 wt.% Nylon-6,6, respectively, and values less than 1 indicate the hopping conduction mechanism. The barrier height (Wm) was found to increase from 0.33 to 0.72 for 0 and 100 wt.% Nylon-6,6, respectively. The ionic conductivity decreases as the concentration of Nylon-6,6 is blended into PVA because increasing the Nylon-6,6 concentration reduces the number of mobile charge carriers. Positron annihilation lifetime (PAL) spectroscopy was used to investigate the free volume's nanostructure. The hole volume size grows exponentially with the concentration of Nylon-6,6 mixed with PVA. The Nylon-6,6/PVA blends' free-volume distribution indicates that there is no phase separation in the blended samples. Mixing PVA and Nylon-6,6 resulted in a negative deviation (miscible blends), as evidenced by the interaction parameter's negative value. The strong correlation between the free-volume size and other macroscopic properties like ionic conductivity suggests that the free-volume size influences these macroscopic properties.

Lithium Vanadium Oxide/Graphene Composite as a Promising Anode for Lithium-Ion Batteries

Lithium vanadium oxide (Li₃VO₄, LVO) is a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity (394 mAh g^-1) and safe working potential (0.5-1.0 V vs. Li⁺/Li). However, its electrical conductivity is low which leads to poor electrochemical performance. Graphene (GN) shows excellent electrical conductivity and high specific surface area, holding great promise in improving the electrochemical performance of electrode materials for LIBs. In this paper, LVO was prepared by different methods. SEM results showed the obtained LVO by sol-gel method possesses uniform nanoparticle morphology. Next, LVO/GN composite was synthesized by sol-gel method. The flexible GN could improve the distribution of LVO, forming a high conductive network. Thus, the LVO/GN composite showed outstanding cycling performance and rate performance. The LVO/GN composite can provide a high initial capacity of 350.2 mAh g^-1 at 0.5 C. After 200 cycles, the capacity of LVO/GN composite remains 86.8%. When the current density increased from 0.2 C to 2 C, the capacity of LVO/GN composite only reduced from 360.4 mAh g^-1 to 250.4 mAh g^-1, demonstrating an excellent performance rate.

In Situ Formed Core-Shell LiZnxMn2-xO4@ZnMn2O4 as Cathode for Li-Ion Batteries

Elemental doping and surface modification are commonly used strategies for improving the electrochemical performance of LiMn₂O₄, such as the rated capacity and cycling stability. In this study, in situ formed core-shell LiZn_xMn_2-xO₄@ZnMn₂O₄ cathodes are prepared by tuning the Zn-doping content. Through comprehensive microstructural analyses by the spherical aberration-corrected scanning transmission microscopy (Cs-STEM) technique, we shed light on the correlation between the microstructural configuration and the electrochemical performance of Zn-doped LiMn₂O₄. We demonstrate that part of Zn²⁺ ions dope into the spinel to form LiZn_xMn_2-xO₄ in bulk and other Zn²⁺ ions occupy the 8a sites of the spinel to form the ZnMn₂O₄ shell on the outermost surface. This in situ formed core-shell LiZn_xMn_2-xO₄@ZnMn₂O₄ contributes to better structural stabilization, presenting a superior capacity retention ratio of 95.8% after 700 cycles at 5 C at 25 °C for the optimized sample (LiZn_0.02Mn_1.98O₄), with an initial value of 80 mAh g^-1. Our investigations not only provide an effective way toward high-performance LIBs but also shed light on the fundamental interplay between the microstructural configuration and the electrochemical performance of Zn-doped spinel LiMn₂O₄.

Three-Dimensional Honeycomb-Like Carbon as Sulfur Host for Sodium-Sulfur Batteries without the Shuttle Effect

Sodium-sulfur batteries operating at ambient temperature are being extensively studied because of the high theoretical capacity and abundant resources, yet the long-chain polysulfides' shuttle effect causes poor cycling performance of Na-S batteries. We report an annealing/etching method to converse low-cost wheat bran to a 3D honeycomb-like carbon with abundant micropores (WBMC), which is smaller than S₈ molecular size (∼0.7 nm). Thus, the microporous structure could only fill small molecular sulfur (S_2-4). The micropores made sulfur a one-step reaction without the shuttle effect due to the formed short-chain polysulfides being insoluble. The WBMC@S exhibits an excellent initial capacity (1413 mAh g^-1) at 0.2 C, outstanding cycling performance (822 mAh g^-1 after 100 cycles at 0.2 C), and high rate performance (483 mAh g^-1 at 3.0 C). The electrochemical performance proves that the steric confinement of micropores effectively terminates the shuttle effect.

Fabrication and Conductivity of Graphite Nanosheet/Nylon 610 Nanocomposites Using Graphite Nanosheets Treated with Supercritical Water at Different Temperatures

In this study, water at high temperatures (150, 175, 200 °C) and in a vacuum state (−0.1 MPa) was applied to graphite nanosheets to enhance surface activity to promote the formation of oxygen-containing functional groups through supercritical water treatment. Nylon 610 nanocomposites (with treated or untreated nanosheets as nanofillers) were then synthesized using interfacial polymerization. X-ray diffraction (XRD) analysis showed that the water treatment did not alter the crystal structure of the carbon nanosheets. Additionally, Fourier transform infrared spectroscopy (FTIR) analysis showed the presence of amide peaks within the nanocomposites, indicating the presence of hydrogen bonding between the nanosheets and the polymer matrix. The intensity of the amide peaks was higher for nanocomposites combined with treated nanosheets than untreated ones. This hydrogen bonding is beneficial to the conductivity of the nanocomposites. The conductivity of treated nanosheets/nylon nanocomposites generally decreased with increasing wt%, while the conductivity of untreated nanosheets/nylon nanocomposites increased with increasing wt%. The decrementing of conductivity in the treated nanosheets/nylon nanocomposites is due to the agglomeration of the nanosheets within the composite. This is in in line with scanning electron microscopy (SEM) results which showed that at higher wt%, the aggregation condition tended to occur. The highest conductivity obtained is 0.004135 S/m, as compared to the conductivity of neat nylon 610, which is 10−14 S/m. This improvement in electrical properties can be attributed to the intact structure of the nanosheets and the interaction between the nanofillers and the nylon 610 matrix. The optimum nylon 610 nanocomposite synthesized was the one incorporated with 0.5 wt% graphite nanosheets treated at 200 °C and −0.1 MPa, which possess the highest conductivity.

Development of Vang Danh anthracite as a cost-effective anode for sodium-ion batteries through a heat-treatment process

This study focuses on the effects of the chemical process and heating time at 900 °C on pristine anthracite coal (provided by Vang Danh coal, Quang Ninh province, Vietnam) and explores its structure and electrochemical performance when used as an anode in Na-ion batteries. After chemical treatment with NaOH and H₂SO₄, the impurity content in the raw material decreased significantly (e.g., ash content dropped from 4.4% to 0.9%, etc.). The interspacing between the graphene layers in the anthracite structure also increased after the heat treatment. Besides, on extending the heating time, the anthracite structure became more disordered than the samples heated for shorter times. Therefore, the intercalation ability of Na⁺ ions in the anthracite structure increased, and the sample heated at 900 °C for 6 hours exhibited the highest reversible capacity of up to 160 mA h g⁻¹ with adequate capacity retention after 100 cycles at C/10 rate.

The treatment process of anthracite materials obtained from Vang Danh and their performance in Na-ion batteries.

Material Design and Energy Storage Mechanism of Mn-Based Cathodes for Aqueous Zinc-Ion Batteries

Mn-based cathodes have been widely explored for aqueous zinc-ion batteries (ZIBs), by virtue of their high theoretical capacity and low cost. However, Mn-based cathodes suffer from poor rate capability and cycling performance. Researchers have presented various approaches to address these issues. Therefore, these endeavors scattered in various directions (e. g., designing electrode structures, defect engineering and optimizing electrolytes) are necessary to be connected through a systematic review. Hence, we comprehensively overview Mn-based cathode materials for ZIBs from the aspects of phase compositions, electrochemical behaviors and energy storage mechanisms, and try to build internal relations between these factors. Modification strategies of Mn-based cathodes are then introduced. Furthermore, this review also provides some new perspectives on future efforts toward high-energy and long-life Mn-based cathodes for ZIBs.

Zeolite Imidazolate Frameworks (ZIFs) Derived Nanomaterials and their Hybrids for Advanced Secondary Batteries and Electrocatalysis

Zeolite imidazolate frameworks (ZIFs), as a typical class of metal-organic frameworks (MOFs), have attracted a great deal of attention in the field of energy storage and conversation due to their chemical structure stability, facile synthesis and environmental friendliness. Among of ZIFs family, the zinc-based imidazolate framework (ZIF-8) and cobalt-based imidazolate framework (ZIF-67) have considered as promising ZIFs materials, which attributed to their tunable porosity, stable structure, and desirable electrical conductivity. To date, various ZIF-8 and ZIF67 derived materials, including carbon materials, metal oxides, sulfides, selenides, carbides and phosphides, have been successfully synthesized using ZIFs as templates and evaluated as promising electrode materials for secondary batteries and electrocatalysis. This review provides an effective guide for the comprehension of the performance optimization and application prospects of ZIFs derivatives, specifically focusing on the optimization of structure and their application in secondary batteries and electrocatalysis. In detail, we present recent advances in the improvement of electrochemical performance of ZIF-8, ZIF-67 and ZIF-8@ZIF-67 derived nanomaterials and their hybrids, including carbon materials, metal oxides, carbides, oxides, sulfides, selenides, and phosphides for high-performance secondary batteries and electrocatalysis.

New enhancement mechanism of an ether-based electrolyte in cobalt sulfide-containing potassium-ion batteries

The performance of potassium (K)-ion batteries (KIBs) is not only dependent on electrode materials but also highly related to the electrolyte. In this work, we obtained a cobalt sulfide (CoS)-containing hybrid by the hydrothermal method and subsequent thermal treatment for K-ion storage. After ether-based electrolyte matching, the CoS-containing hybrid achieves a specific capacity of 229 mA h g^-1 at 1 A g^-1 after 300 cycles, and presents enhanced performance in the ether-based electrolyte. According to our measurement and calculation, the CoS-containing hybrid in the ether-based electrolyte promotes the formation of a highly anionic coordination solvated structure, which contributes to the enhancement of the stability of the electrolyte for K-ion storage. In addition, the strong coordination of anions also facilitates the rapid separation of the solvent during the potassiation process, which is also in favor of the decrease of the side reaction of the CoS@RGO hybrid for KIBs. We believe that our work will provide a new perspective on electrolyte engineering to boost the electrode material performance for K-ion storage.

Surface potential-determined performance of Ti3C2T2 (T = O, F, OH) and Zr3C2T2 (T = O, F, OH, S) MXenes as anode materials of sodium ion batteries

Sodium ion batteries (SIBs) have attracted increasing attention due to their low cost and abundant reserves of sodium, but their ideal anode materials still need to be explored. MXenes could be candidate electrode materials due to their excellent electrical conductivity and large specific surface area. In this work, the theoretical performance of Ti- and Zr-containing MXenes Ti₃C₂T₂ (T = O, F, OH) and Zr₃C₂T₂ (T = O, F, OH, S) as SIB anode materials is investigated. The influence of the Hubbard U correction is discussed, and the behaviour at the MXene surface with the partial occupation of sodium atoms is considered. Including the weight and volume of adsorbed sodium atoms, Ti₃C₂O₂ presents the best performance among the seven MXenes studied. Its mass and volumetric capacities are 299 mA h g^-1 and 993 mA h cm^-3 respectively, and the migration barrier and open circuit voltage are 0.138 eV and 0.421 V. Both Zr₃C₂O₂ and Zr₃C₂S₂ can adsorb double layers of sodium atoms on both sides, and the former shows a higher capacity because of its lower weight and smaller volume. The mass and volumetric capacities of Zr₃C₂O₂ are 254 mA h g^-1 and 913 mA h cm^-3 respectively. More importantly, the surface potential is determined to be an effective descriptor for selecting electrode materials. The migration barrier is proportional to the fluctuation amplitude of the surface potential. A low surface potential generally implies a high capacity. A large open circuit voltage is prone to appear in the structure with a large fluctuation amplitude and a low average value of its surface potential.

A Review on Electrode Materials of Fast-Charging Lithium-Ion batteries

In recent years, the driving range of electric vehicles (EVs) has been dramatically improved. But the large-scale adoption of EVs still is hindered by long charging time. The high-energy LIBs are unable to be safely fast-charged due to their electrode materials with unsatisfactory rate performance. Thus it is necessary to summarize the properties of cathode and anode materials of fast-charging LIBs. In this review, we summarize the background, the fundamentals, electrode materials and future development of fast-charging LIBs. First, we introduce the research background and the physicochemical basics for fast-charging LIBs. Second, typical cathode materials of LIBs and the method to enhancing their fast-charging properties are discussed. Third, the anode materials of LIBs and the strategies for improving their fast-charging performance are analyzed. Finally, the future development of the cathode materials in fast-charging LIBs is prospected.

Sb-Doped metallic 1T-MoS2 nanosheets embedded in N-doped carbon as high-performance anode materials for half/full sodium/potassium-ion batteries

Metal 1T phase molybdenum disulfide (1T-MoS₂) is being actively considered as a promising anode due to its high conductivity, which can improve electron transfer. Herein, we elaborately designed stable Sb-doped metallic 1T phase molybdenum sulfide (1T-MoS₂-Sb) with a few-layered nanosheet structure via a simple calcination technique. The N-doping of the carbon and Sb-doping induce the formation of T-phase MoS₂, which not only effectively enhances the entire stability of the structure, but also improves its cycling performance and stability. When employed as an anode of sodium-ion batteries (SIBs), 1T-MoS₂-Sb exhibits a reversible capacity of 493 mA h g^-1 at 0.1 A g^-1 after 100 cycles and delivers prominent long-term performance (253 mA h g^-1 at 1 A g^-1 after 2200 cycles) along with decent rate capability. Paired with a Na₃V₂(PO₄)₃ cathode, it displays a superior capacity of 242 mA h g^-1 at 0.5 A g^-1 over 100 cycles, which is one of the best performances of a MoS₂-based full cell for SIBs. Employed as the anode for potassium-ion batteries (PIBs), it exhibits a satisfactory specific capacity of 343 mA h g^-1 at 0.1 A g^-1 after 100 cycles. This facile strategy will provide new insights for designing T-phase advanced anode materials for SIBs/PIBs.