Reversible Specific Capacity Research Articles

Study on the hard carbon anode from different precursors for sodium ion batteries

Sodium-ion batteries (SIBs) are commonly utilized in power storage applications. It can be used as alternatives to lithium-ion batteries. Nevertheless, the development of SIBs is restricted by anode materials due to the high redox potential and large irreversible capacity. As a common anode material of SIBs, hard carbon exhibits a substantial interlayer spacing and a excellent reversible specific capacity, while the properties and costs are affected by its precursors. This article mainly describes the sodium storage principle of hard carbon and compares the performances as well as modification methods of hard carbon produced from various precursors. The hard carbon basing on coal has the advantages of low cost due to the abundant reserves of coal precursors and low redox potential. Biomass-based hard carbon has natural pores which can assist the sodium ions transport in carbon materials. We further explain the effects of modification strategies such as heteroatom doping, activation treatment and mechanical ball milling on electrochemical properties of hard carbon. Finally, this paper recognizes the existing problems and corresponding solutions of materials made of hard carbon and looks forward to the future research focus on hard carbon materials.

Molten salt assisted synthesis of Si/C nanocomposite derived from palygorskite and sodium alginate for electrochemical lithium storage.

Silicon/carbon (Si/C) nanocomposites are considered as one of the most promising anode materials for lithium-ion batteries due to their high capacity and suitable lithiation potential. However, the complex and time-consuming preparation processes of silicon-based nanocomposites and the unexpected silicon carbide generated during high treatment make it difficult to achieve high-performance Si/C nanocomposites for practical applications. Herein, a silicon/carbon nanocomposite is successfully prepared through a facile and eco-friendly molten salt assisted precarbonization-reduction method using palygorskite (PAL) and sodium alginate as raw materials. Based on physical characterizations, it is demonstrated that the sodium alginate plays a key role in the successful preparation of Si/C nanocomposite, which not only boosts uniform embedding of PAL nanoparticles in the carbon matrix but also releases molten sodium salt to suppress the formation of unexpected SiC. When used as an alternative anode material for lithium-ion battery applications, the as-obtained Si/C composite delivers a high reversible specific capacity of 1362.7 mA h g-1 with an initial Coulombic efficiency of 70.3% at a current density of 200 mA g-1 and excellent long-term cycling stability. The findings here provide a facile and eco-friendly molten salt assisted precarbonization-reduction method for high-performance silicon/carbon anode materials.

Enhancing the potassium-ion storage performance of potassium manganese oxide cathode by single-element doping strategies

Layered manganese-based oxides are considered as ideal cathode materials for potassium-ion batteries (PIBs) due to their ease of synthesis and relatively large interlayer spacing. Nevertheless, the Jahn-Teller effect of Mn3+ and the irreversible phase transitions in high-voltage regions of layered manganese-based oxide leads to slow diffusion kinetics of potassium ions and severe capacity fading. Herein, a series of single-element doped manganese-based oxide cathodes K0.5Mn0.98X0.02O2 (X = Fe, Mg, Cu, Ti and Zn) are designed and investigated. The results demonstrate that trace doping with these elements stabilizes the layered structure of KMnO2 cathode materials, improves the diffusion coefficient of K+, and effectively suppresses the P3-O3-P3 phase transition in high-voltage regions. Among the doping-samples, the K0.5Mn0.98Fe0.02O2 exhibits outstanding reversible specific capacity of 127 mAh g−1 at a current density of 20 mA g−1. Meanwhile, K0.5Mn0.98Ti0.02O2 demonstrates exceptional cycling stability and rate capability, retaining 83.8 % of its initial capacity after 300 cycles at 200 mA g−1, and maintaining a high specific capacity close to 40 mAh g−1 even at 1000 mA g−1. This study validates the feasibility of trace element doping in enhancing the electrochemical performance of layered Mn-based cathode materials for PIBs.

D‐Band Center Modulation of Metallic Co‐Incorporated Co7Fe3 Alloy Heterostructure for Regulating Polysulfides in Highly Efficient Lithium‐Sulfur Batteries

AbstractLithium‐sulfur (Li‐S) batteries, with their high theoretical energy density and cost‐effectiveness, have become one of the most promising next‐generation energy storage devices. However, they still face challenges such as the “shuttle effect” caused by the dissolution of polysulfide intermediates and the slow sulfur conversion kinetics. In this study, based on the Co7Fe3 alloy catalyst, additional Co metal is introduced to form a Co7Fe3Co catalyst with a heterostructure through a simple heat treatment process. This catalyst is incorporated into Ketjenblack (KB) to form a sulfur‐infused cathode material (designated as S/KB/Co7Fe3Co). Li‐S batteries using S/KB/Co7Fe3Co as the cathode demonstrate outstanding electrochemical performance, maintaining a reversible specific capacity of over 500 mAh g−1 after 1000 cycles at a current density of 1 C, with a capacity decay rate of 0.046% per cycle. DFT theoretical calculations and experimental results both reveal that the introduction of additional Co effectively regulates the d‐band center of the material, enhancing the adsorption of polysulfide intermediates by Co7Fe3Co and promoting bidirectional catalytic sulfur conversion. This work highlights the importance of the simple construction of heterostructured catalytic materials and their role in improving the performance of Li‐S batteries.

Structural disorder Triggered by small organic molecules Boosting δ-MnO2 cathode for Ultra‐Stable aqueous zinc ion batteries

The inferior cycling stability of MnO2-based cathodes, resulting from Mn dissolution and crystal structure transition during Zn-ion insertion/extraction, poses a significant challenge hindering their widespread adoption in aqueous zinc-ion batteries (AZIBs). To mitigate these issues, we propose an approach involving the incorporation of small organic molecules (methylformamide, dimethylformamide, and formamide) to modify the crystalline structure of MnO2. These molecules, characterized by their low orbital energy levels, facilitate the creation of energetically equivalent electron transfer pathways with the unoccupied eg orbitals in Mn4+, as evidenced by the DFT calculations. Furthermore, they modulate the electron cloud density of Mn-O and introduce structural disorder in the MnO2 crystalline lattice, thereby greatly enhancing the structural stability of the Mn-based cathode. In AZIBs tests, the MnO2/methylformamide (MO/NMF) cathode demonstrates a remarkable reversible specific capacity exceeding 270 mAh g−1 at 1 A g−1 and exceptional durability, exhibiting negligible capacity degradation after 2000 cycles at 3 A g−1. In-situ X-ray diffraction, neutron powder diffraction and high-angle annular dark-field scanning transmission electron microscopy analyses confirm the structure stability of MO/NMF during Zn-ion insertion/extraction, attributed to the NMF modification. Additionally, the electrochemical data indicate that modifications with dimethyl formamide and formamide also positively impact the electrochemical performance of the MnO2 cathode. This study offers valuable insights for the development of high-performance Mn-based cathodes.

Improving the Energy Density of Potassium‐Ion Batteries Through Defect Engineering

AbstractPotassium‐ion batteries (PIBs) have a significant cost advantage in resources, making their commercial application imminent. Presently, the cycling lifespan and energy density of PIBs lag behind those of lithium‐ion batteries, highlighting the crucial need for anode materials suitable for potassium storage. This paper used high‐pressure heat treatment and extraction methods to obtained toluene insoluble (TI) as a carbon matrix, followed by nickel and nitrogen co‐doping to synthesized anode materials (NiNTI). NiNTI is characterized by defect engineering such as thermal condensation polymerization and template doping, which destroys the flattening of the material, provides more active sites, forms more disordered carbon structures, generates a large number of defects and structural vacancies, and improves the electronic conductivity of NiNTI materials. In the NiNTI half‐cell configuration, operating at a current density of 0.1 A g−1, the reversible specific capacity reaches 364 mAh g−1, with an initial coulombic efficiency of 64.9%.

Nano ZnO modified amorphous carbon materials enabling long-cycle performance and high-capacity for lithium/sodium-ion batteries

Zinc-modified carbon materials exhibit high specific capacity, good safety, and low self-discharge, making them promising anode materials for lithium-ion and sodium-ion batteries. However, the high cost of raw materials, complex fabrication processes, and limited cycle life remain significant challenges to their further development. In this study, we elucidated a two-step process, simple in technique and suitable for large-scale production, for in-situ zinc modification of amorphous carbon. The synthesized carbon material exhibited superior reversible specific capacity (maintaining 780.27 mAh·g−1 capacity after 80 cycles at 50 mA·g−1 current density), high cycling stability (maintaining Coulombic efficiency at 100.06 % after 15,000 cycles at 10 A·g−1 current density), and good application value (achieving a capacity of 89.67 mAh·g−1 after 1000 cycles at 200 mA·g−1 current density for the assembled MFAC-Zn||NVP full cell). Through our investigation, we discovered that Nano ZnO not only directly participate in electrochemical reactions but also effectively improve the microstructure of amorphous carbon, increasing its three-dimensional axial stacking and providing more reaction sites. The enrichment of open pores significantly enhances the diffusion efficiency of ions within the carbon-based matrix. The superior diffusion ability of alkali metal-ion in the electrode is the reason for the excellent electrochemical performance of Zinc-modified amorphous carbon. Moreover, the incorporation of Nano ZnO aids in the formation of a robust and thin SEI layer. This significantly enhances the stability of the electrode materials during cycling and improves charge transfer efficiency during the charge-discharge process. Our study provides a new strategy for adjusting the internal microstructure of amorphous carbon materials to achieve high-performance lithium/sodium storage.

In Situ Synthesis of CoMoO4 Microsphere@rGO as a Matrix for High-Performance Li-S Batteries at Room and Low Temperatures.

Lithium-sulfur batteries (Li-S batteries) have attracted wide attention due to their high theoretical energy density and the low cost of sulfur cathode material. However, the poor conductivity of the sulfur cathode, the polysulfide shuttle effect, and the slow redox kinetics severely affect their cycling performance and Coulombic efficiencies, especially under low-temperature conditions, where these effects are more exacerbated. To address these issues, this study designs and synthesizes a microspherical cobalt molybdate@reduced graphene oxide (CoMoO4@rGO) composite material as the cathode material for Li-S batteries. By growing CoMoO4 nanoparticles on the rGO surface, the composite material not only provides a good conductive network but also significantly enhances the adsorption capacity to polysulfides, effectively suppressing the shuttle effect. After 100 cycles at room temperature with a current density of 1 C, the reversible specific capacity of the battery stabilizes at 805 mAh g-1. Notably, at -20 °C, the S/CoMoO4@rGO composite achieves a reversible specific capacity of 840 mAh g-1. This study demonstrates that the CoMoO4@rGO composite has significant advantages in suppressing polysulfide diffusion and expanding the working temperature range of Li-S batteries, showing great potential for applications in next-generation high-performance Li-S batteries.

In situ catalyzed growth of carbon nanotube with asphalt cladding as a bicarbon synergistic framework of silicon anodes for lithium-ion batteries.

Silicon, as the most promising advanced anode material for lithium-ion batteries, faces challenges in large-scale industrial production due to the significant volume expansion effect. In this investigation, Si/CNTs/C composite materials were effectively produced through high-temperature carbonization utilizing asphalt, silicon, hexahydrate ferric chloride, and melamine as primary elements. The distinctive dual-carbon framework of asphalt-derived carbon and carbon nanotubes alleviates the volume expansion of silicon, thereby stabilizing the composite material's structure. Testing the electrochemical performance reveals that the Si/CNTs/C composite material exhibits a reversible specific capacity of 1187 mAh g-1 with a capacity retention rate of 92.6% after 150 cycles at a current density of 0.2 A g-1. Even after 500 cycles at a current density of 1 A g-1, it sustains a specific capacity of 879.4 mAh g-1 with a capacity retention rate of 87.9%, showcasing outstanding electrochemical performance.

Hierarchical Flower Array NiCoOOH@CoLa‐LDH Nanosheets for High‐Performance Supercapacitor and Alkaline Zn Battery

AbstractNickel oxyhydroxide based energy storage materials have been largely confined by insufficient exposure of active sites which results in low energy efficiency and poor stability. In order to resolve the problems, hierarchical flower array heterostructure NiCoOOH@CoLa‐LDH (denoted as NC@CL) nanosheets are designed with NiCo oxyhydroxide (NiCoOOH, denoted as NC) being tightly covered on CoLa layered double hydroxide (CoLa‐LDH, denoted as CL) nanosheet. This rational design creates more active sites, enlarges the electrode‐electrolyte contact area, improves electron conductivity, and prevents agglomeration during the cycling charge–discharge processes. Density functional theory calculations and differential charges concurrently illustrate that heterostructure formation optimizes the reaction kinetics and promotes electron redistribution. Benefiting from the heterogeneous structure and rich electro‐active sites caused by NC, NC@CL displays outstanding reversible specific capacitance (3228 F g−1 at 1 A g−1). The aqueous rechargeable alkaline Zn battery NC@CL//Zn exhibits a high capacity of 381.1 mA h g−1 at 0.5 A g−1 and cycling durability (98% capacity retention after cycling at 5 A g−1 for 2000 cycles). The excellent electrochemical performances indicate that NC@CL has great application potential as electrode material for aqueous energy storage device.

Ball-Milling-Assisted N/O Codoping for Enhanced Sodium Storage Performance of Coconut-Shell-Derived Hard Carbon Anodes in Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are regarded as cost-effective alternatives or competitors to lithium-ion batteries for large-scale electric energy storage applications. However, their development has been hindered by the high cost of hard carbon (HC) anodes and poor electrochemical performance. To enhance the sodium storage capacity and rate performance of HC, this study accelerated the electrochemical performance of coconut-shell-derived HC anodes for SIBs through N/O codoping using ball milling and pyrolysis. Experimental results demonstrate that the simultaneous introduction of N and O generates a synergistic effect, increasing the surface oxygen-containing functional groups, defects, and interlayer spacing of coconut-shell-derived HC through the codoping of light elements. The excellent strategy has increased the slope capacity and platform capacity of HC, and the synergistic modification of N/O has increased its reversible specific capacity from 272 to 343 mA h g-1 (30 mA g-1), with a retention rate of approximately 92.1% after 100 cycles. In addition, it also exhibits an excellent rate performance, reaching 178 mA h g-1 at 1500 mA g-1. In summary, this study presents an effective strategy for modifying biomass-derived HC.

The Development and Prospect of Stable Polyanion Compound Cathodes in LIBs and Promising Complementers.

Cathode materials are usually the key to determining battery capacity, suitable cathode materials are an important prerequisite to meet the needs of large-scale energy storage systems in the future. Polyanionic compounds have significant advantages in metal ion storage, such as high operating voltage, excellent structural stability, safety, low cost, and environmental friendliness, and can be excellent cathode options for rechargeable metal-ion batteries. Although some polyanionic compounds have been commercialized, there are still some shortcomings in electronic conductivity, reversible specific capacity, and rate performance, which obviously limits the development of polyanionic compound cathodes in large-scale energy storage systems. Up to now, many strategies including structural design, ion doping, surface coating, and electrolyte optimization have been explored to improve the above defects. Based on the above contents, this paper briefly reviews the research progress and optimization strategies of typical polyanionic compound cathodes in the fields of lithium-ion batteries (LIBs) and other promising metal ion batteries (sodium ion batteries (SIBs), potassium ion batteries (PIBs), magnesium ion batteries (MIBs), calcium ion batteries (CIBs), zinc ion batteries (ZIBs), aluminum ion batteries (AIBs), etc.), aiming to provide a valuable reference for accelerating the commercial application of polyanionic compound cathodes in rechargeable battery systems.

Preparation of high strength and rigidity carbon layer on SiO material surface by dynamic CVD method using gas carbon source C2H2

The main issue in the application of silicon-based negative electrode materials is the inevitable volume expansion, leading to negative electrode material fracture, which severely impacts the performance of batteries. This study employed Chemical Vapor Deposition (CVD) (C2H2@SiO), solid-phase coating method (Pitch@SiO), and liquid-phase coating method (RGFQ@SiO) to coat the surface of SiO materials with a dense amorphous carbon structure. Material property analysis revealed that C2H2@SiO has a relatively small specific surface area (1.8 m2 g−1) and surface carbon increment (2.4 %). It exhibited high reversible specific capacity (1563.4 mAh g−1), high initial Coulombic efficiency (81.45 %), and low volume expansion rate (9.3 %). Mechanical performance testing indicated that the surface carbon layer Young's modulus of C2H2@SiO was the highest (35 GPa), suggesting that using the CVD method to obtain a dense carbon layer can enhance the structural strength of the material. Based on the electrochemical-mechanical coupling theory simulation analysis of the stress during the charge-discharge process of electrode materials, the evolution of concentration and stress field during lithium insertion process was obtained, showing that the coating can further improve the electrochemical and mechanical performance of the negative electrode materials effectively. Additionally, the negative electrode sheets fabricated using sample C2H2@SiO were assembled into 18650 cylindrical batteries, exhibiting excellent cycling performance in 1000 cycles at 25 °C with a capacity retention rate of 85.7 %, along with good rate capability and high/low-temperature performance. The conclusions of this study provide certain guidance for the design and optimization of negative electrode materials for battery electrodes.

Enhancing lithium storage performance of Carbon/SiOx composite via coating edge-nitrogen-enriched carbon

Silicon oxide (SiOx) exhibits promising potential as a lithium-ion battery anode. However, its practical application is impeded by low electrical conductivity and significant volumetric expansion. To overcome these limitations, we developed a novel co-precipitation and selectively etching approach that leveraged the nitrogen-retaining effect of ZnNCN to prepare an edge-nitrogen-enriched carbon/SiOx composite (NEC@LC-SiOx). This NEC@LC-SiOx showed enhanced electrical conductivity and reduced volumetric expansion. Our innovative approach effectively prevented excessive decomposition of nitrogen species, resulting in a high nitrogen doping content of 21.67 at.% while maintaining a stable structure and mitigated volume expansion during charging and discharging. Consequently, the prepared NEC@LC-SiOx exhibited excellent performance as an anode material for lithium-ion batteries, demonstrating a high reversible specific capacity of 802 mAh/g and outstanding rate capability. This work presents a novel strategy for designing high-performance SiOx anode materials.

Structurally-constrained wrinkled NiO nanomembranes for high-performance lithium and sodium storage

In light of its exceptional capacity and safety features, nickel oxide (NiO) has emerged as a highly promising electrode material for advanced lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), which operate through conversion mechanisms, meeting the growing demand for high-efficiency rechargeable batteries. To address the capacity degradation challenges associated with NiO anodes, we present an innovative approach involving the fabrication of wrinkled NiO nanomembranes through magnetron sputtering deposition followed by thermal treatment. This distinctive three-dimensional, ultra-thin architecture integrates nanostructural and microstructural features that effectively reduce ionic diffusion distances and mitigate dimensional fluctuations during cycling, thereby markedly enhancing the electrochemical performance and reliability. Specifically, for lithium storage, these wrinkled NiO nanomembranes achieve an impressive reversible specific capacity of 773 mA h g−1 at 100 mA g−1, with excellent rate capability of 468 mA h g−1 at 5000 mA g−1 and long-term cycling performance, maintaining 523 mA h g−1 at 500 mA g−1 even after 1000 cycles. Likewise, for sodium storage, they exhibit a substantial reversible capacity of 288 mA h g−1 at 50 mA g−1 and retain 202 mA h g−1 at 200 mA g−1 after 100 cycles. These findings underscore the promising application of wrinkled NiO nanomembranes as robust anodic materials for high-performance LIBs and SIBs.

Biomass derived 3D N, P co-doped porous carbon incorporated with Ni-Cu bimetallic phosphide: Synergistic effect of Ni-Cu boosting Na+ storage performance

Transition metal phosphides (TMPs) as promising anode materials for sodium-ion batteries (SIBs) due to their amazing properties such as high theoretical specific capacity, various bond types and good electrical conductivity. However, TMPs are still facing poor cycling stability and unsatisfactory specific capacity, which restrict their practical application. Herein, NixCu3-xP incorporated in biomass derived 3D N, P co-doped porous carbon (NixCu3-xP-NPC) is constructed as SIB anode and the electrochemical behaviors with various Ni/Cu ratios are explored. The synergistic effect of Ni-Cu in NixCu3-xP is approved by the resulting investigation, and density functional theory (DFT) calculation further confirmed its important influence in enhancing electronic conductivity and boosting Na+ storage. Evidently, the optimum synergistic effect was observed when Ni0.15Cu2.85P/NPC is utilized for SIB anode. It exhibits a reversible specific capacity of 663 mAh g−1 after 200 cycles at 0.2 A g−1, long cycling stability (467 mAh g−1 after 1000 cycles at 1.0 A g−1), and excellent rate capability (432 mAh g−1 at 2.0 A g−1). The ex-situ X-ray diffraction and ex-situ X-ray photoelectron spectroscopy verify the combined conversion mechanism of Ni and Cu during sodiation/desodiation processes, which is greatly favorable for high specific capacity and cycling stability.

CVD-Synthesized Titanium Carbide Nanoflowers as High-Performance Anodes for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have emerged as promising candidates for energy storage applications due to the abundance and low cost of sodium. However, the larger radius of sodium ions limits their diffusion kinetics within electrode materials and contributes to electrode volume expansion. Here, we successfully synthesized porous titanium carbide (TiC) nanoflowers through chemical vapor deposition (CVD). The TiC nanoflowers exhibit exceptional electrochemical performance as SIB anodes, with their porous structure enhancing the conductivity, mechanical stability, and Na-ion diffusion. The TiC nanoflowers demonstrate a high reversible specific capacity of 73.5 mAh g-1 at 1 A g-1 after 2500 cycles, corresponding to an impressive capacity retention of 80.81%. Additionally, we developed a full sodium-ion cell utilizing TiC nanoflowers as the anode and Na3V2(PO4)3 as the cathode, which demonstrates a substantial reversible capacity and outstanding cycling stability. Our work presents a promising strategy for synthesizing nanostructured TiC materials as anode electrodes for SIBs.

Electronic Confinement-Restrained Anti-Site Defects in Sodium-Rich Phosphates Toward Multi-Electron Transfer and High Energy Efficiency.

Sodium (Na) super-ionic conductor structured Na3MnTi(PO4)3 (NMTP) cathodes have garnered interest owing to their cost-effectiveness and high operating voltages. However, the voltage hysteresis phenomenon triggered by anti-site defects ( -ASD), namely, the occupation of Mn2+ in the Na2 vacancies in NMTP, leads to sluggish diffusion kinetics and low energy efficiency. This study employs an innovative electronic confinement-restrained strategy to achieve the regulation of -ASD. Partial replacement of titanium (Ti) with electron-rich vanadium (V) favors strong electronic interactions with Mn2+, restraining Mn2+ migration. The results suggest that this strategy can significantly increase the vacancy formation energy and migration energy barrier of manganese (Mn), thus inhibiting -ASD formation. As proof of this concept, an Na-rich Na3.5MnTi0.5V0.5(PO4)3 (NMTVP) material is designed, wherein the electronic interaction enhanced the redox activity and achieved more Na+ storage under high-voltage. The NMTVP cathode delivered a reversible specific capacity of up to 182.7 mAh g-1 and output an excellent specific energy of 513.8Wh kg-1, corresponding to ≈3.2 electron transfer processes, wherein the energy efficiency increased by 35.5% at 30C. Through the confinement effect of electron interactions, this strategy provides novel perspectives for the exploitation and breakthrough of high-energy-density cathode materials in Na-ion batteries.

Enhancing Electrochemical Performance of Si@CNT Anode by Integrating SrTiO3 Material for High-Capacity Lithium-Ion Batteries

Silicon (Si) has attracted worldwide attention for its ultrahigh theoretical storage capacity (4200 mA h g−1), low mass density (2.33 g cm−3), low operating potential (0.4 V vs. Li/Li+), abundant reserves, environmentally benign nature, and low cost. It is a promising high-energy-density anode material for next-generation lithium-ion batteries (LIBs), offering a replacement for graphite anodes owing to the escalating energy demands in booming automobile and energy storage applications. Unfortunately, the commercialization of silicon anodes is stringently hindered by large volume expansion during lithiation–delithiation, the unstable and detrimental growth of electrode/electrolyte interface layers, sluggish Li-ion diffusion, poor rate performance, and inherently low ion/electron conductivity. These present major safety challenges lead to quick capacity degradation in LIBs. Herein, we present the synergistic effects of nanostructured silicon and SrTiO3 (STO) for use as anodes in Li-ion batteries. Si and STO nanoparticles were incorporated into a multiwalled carbon nanotube (CNT) matrix using a planetary ball-milling process. The mechanical stress resulting from the expansion of Si was transferred via the CNT matrix to the STO. We discovered that the introduction of STO can improve the electrochemical performance of Si/CNT nanocomposite anodes. Experimental measurements and electrochemical impedance spectroscopy provide evidence for the enhanced mobility of Li-ions facilitated by STO. Hence, incorporating STO into the Si@CNT anode yields promising results, exhibiting a high initial Coulombic efficiency of approximately 85%, a reversible specific capacity of ~800 mA h g−1 after 100 cycles at 100 mA g−1, and a high-rate capability of 1400 mA g−1 with a capacity of 800 mA h g−1. Interestingly, it exhibits a capacity of 350 mAh g−1 after 1000 lithiation and delithiation cycles at a high rate of 600 mA hg−1. This result unveils and sheds light on the design of a scalable method for manufacturing Si anodes for next-generation LIBs.

CeO2 anchored in VO2@C rambutan-like microsphere achieving advanced zinc storage

Low-cost and high-safety aqueous zinc ion batteries (AZIBs) show great potential in energy storage for the grid. We propose a strategy to construct the self-assembled microspheres with the cerium oxide nanocrystals anchored on B-phase vanadium dioxide nanobelts, which are encapsulated by carbon (CVC), as cathode for high capacity and cycle stability of AZIBs. The rambutan-like structure with large specific surface area provides more active sites for the overall improvement of reaction kinetics; the carbon layer relieves vanadium dioxide from dissolving in the electrolyte while enhancing electron transfer rate; and electrocatalytic activity of cerium oxide accelerates redox reaction to enhance the performance of the cells. Consequently, the CVC electrode exhibits excellent electrochemical properties, including a reversible specific capacity (490 mAh g−1 at 0.1 A g−1), incredible cycle (84 % capacity retention after 1000 cycles at 5 A g−1). The excellent performance demonstrates the correctness of the combined internal and external modification strategy, while the simple hydrothermal method and inexpensive raw materials point to a new direction for the large-scale preparation of high-performance aqueous zinc ion batteries.