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In the critical situation of energy shortage and environmental problems, Si has been regarded as one of the most potential anode materials for next-generation lithium-ion batteries as a result of the relatively low delithiation potential and the eminent specific capacity. However, a Si anode is subjected to the huge volume expansion–contraction in the charging–discharging process, which can touch off pulverization of the bulk particles and worsens the cycle life. Herein, to reduce the volume change and improve the electrochemical performance, a novel Si@SiOx/C anode with a core–shell structure is designed by spray and pyrolysis methods. The SiOx/C shell not only ensures the structure stability and proves the high electrical conductivity but also prevents the penetration of electrolytes, so as to avoid the repetitive decomposition of electrolytes on the surface of Si particle. As expected, Si@SiOx/C anode maintains the excellent discharge capacity of 1,333 mAh g−1 after 100 cycles at a current density of 100 mA g−1. Even if the current density reaches up to 2,000 mA g−1, the capacity can still be maintained at 1,173 mAh g−1. This work paves an effective way to develop Si-based anodes for high-energy density lithium-ion batteries.

Heterostructure engineering and oxygen vacancy engineering are the most promising modification strategies to reinforce the Zn 2+ ion storage of vanadium oxides. Herein, a rare mixed-dimensional material ( VO x ), composed of V 2 O 5 (2D), V 3 O 7 (3D), and V 6 O 13 (3D) heterostructures, rich in oxygen vacancies, was synthesized via thermal decomposition of layered ammonium vanadate. The VO x cathode provides an exceptional discharge capacity (411 mA h g -1 at 0.1 A g -1 ) and superior cycling stability (the capacity retention remains close to 100% after 800 cycles at 2 A g -1 ) for aqueous zinc-ion batteries (AZIBs). Ex situ characterizations confirm that the byproduct Zn 3 V 2 O 7 (OH) 2 · n H 2 O is generated/decomposed during discharge/charge processes. Furthermore, VO x demonstrates reversible intercalation/deintercalation of H + /Zn 2+ ions, enabling efficient energy storage. Remarkably, a reversible crystal-to-amorphous transformation in the V 2 O 5 phase of VO x during charge-discharge was observed. This investigation reveals that mixed-dimensional heterostructured vanadium oxide, with abundant oxygen vacancies, serves as a highly promising electrode material for AZIBs, further advancing the comprehension of the storage mechanism within vanadium-based cathode materials.

In the critical situation of energy shortage and environmental problems, Si has been regarded as one of the most potential anode materials for next-generation lithium-ion batteries as a result of the relatively low delithiation potential and the eminent specific capacity. However, a Si anode is subjected to the huge volume expansion-contraction in the charging-discharging process, which can touch off pulverization of the bulk particles and worsens the cycle life. Herein, to reduce the volume change and improve the electrochemical performance, a novel Si@SiO x /C anode with a core-shell structure is designed by spray and pyrolysis methods. The SiO x /C shell not only ensures the structure stability and proves the high electrical conductivity but also prevents the penetration of electrolytes, so as to avoid the repetitive decomposition of electrolytes on the surface of Si particle. As expected, Si@SiO x /C anode maintains the excellent discharge capacity of 1,333 mAh g -1 after 100 cycles at a current density of 100 mA g -1 . Even if the current density reaches up to 2,000 mA g -1 , the capacity can still be maintained at 1,173 mAh g -1 . This work paves an effective way to develop Si-based anodes for high-energy density lithium-ion batteries., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Li, Zhang, Wang, Teng, Nan, Dong, Bai and Liu.)

Nanocomposites consisting of hexagonal WO 3 nanorods embedded into nitrogen, sulfur co-doped reduced graphene oxide nanosheets (h-WO 3 /NSG) have been synthesized through a combination of ultrasonic processing and hydrothermal reactions. The nanocomposite containing 54 ​wt% of (N, S)-doped reduced graphene oxide shows an excellent discharge capacity of 1030 mAh g-1 at the first cycle and high rate capacities ranging from 513 to 150 mAh g-1 at the current density ranging from 100 to 2000 ​mA ​g-1, respectively. In addition, the synthesized WO 3 /NSG nanocomposite also exhibits remarkable cycle stability with a high discharge capacity of 196 mAh g-1 at the current density of 1500 ​mA ​g-1 for 200 cycles. The excellent electrochemical performance of h-WO 3 /NSG nanocomposite can be attributed to synergistic contributions from (1) the small size of WO 3 nanorods, which increases the contact surface area with the electrolyte, effectively shortening the diffusion length of Li+ ions leading to high Li+ incorporation within h-WO 3 ; (2) the structural support provided by the NSG matrix, which alleviates the large volume change of WO 3 nanorods during Li+ insertion/extraction; and (3) the large numbers of surface defects provided by nitrogen and sulfur co-dopants, which serve as channels to improve the Li+ diffusion. Furthermore, electrochemical impedance spectroscopy (EIS) measurement demonstrates that nitrogen, sulfur co-doped reduced graphene oxide can reduce the electrochemical impedance of the electrode, further improving the electrochemical performance of the anode. This study provides important strategies for the design of future high performance anode materials for lithium ion battery. A uniform integration of sub-ten nanometer scale h-WO 3 nanorods into (N,S) co-doped reduced graphene oxide leads to a high performance anode material for LIBs featuring superior initial discharge capacity and a remarkable structural stability during several hundred charge/discharge cycles under a large current density. Image 1 • Excellent electrochemical performance of h-WO 3 /NSG nanocomposite. • Small size of WO 3 nanorods shortens the diffusion length of Li+ ions. • NSG matrix alleviates large volume change of WO 3 nanorods. • Surface defects provided by N, S co-dopants improve Li+ diffusion. [ABSTRACT FROM AUTHOR]