Fabrication of VO Nanorings on a Porous Carbon Architecture for High-Performance Li-Ion Batteries

Partially amorphous vanadium oxysulfide for achieving high-performance Li-ion batteries

Vanadium-based materials exhibit a high theoretical capacity and diverse valence states, rendering them promising candidate anodes for lithium-ion batteries (LIBs). However, the cycling and rate performance are limited by their weak structural stability and electrical conductivity. Herein, a rational amorphization strategy has been developed to construct dual-anion vanadium oxysulfide nanoflowers (VSO NFs) with partial amorphous components and abundant oxygen vacancies as anode material for LIBs. Both experimental and theoretical calculations results suggest that the introduction of amorphous components and oxygen vacancies significantly improves its electronic conductivity and provides abundant channels and active sites for the movement of Li ions. As expected, the VSO NFs electrode can provide an ultrahigh capacity (672.3 mAh/g at 0.1 A/g) and excellent rate performance (433.1 mAh/g at 2.0 A/g), as well as remarkable cyclic stability (361.7 mAh/g at 2.0 A/g after 600 cycles). Finally, the assembled VSO NFs//LiFePO4 full battery also shows outstanding rate capability and cycling life. Therefore, this amorphous strategy can serve as a guideline for manufacturing high-performance anode materials in electrochemical energy-storage fields.

Synergistic effect of oxygen defects and calabash-like hollow carbon matrix enables VO2 as high-performance cathode for zinc ion battery

Vanadium dioxide (VO2) materials exhibit significant theoretical specific capacity, which is ascribed to multi-electron transfer reactions and unique tunneled structures. However, the low electronic conductivity and sluggish reaction kinetics of VO2 have impeded its further development. Hence, in this study, we employed a synergistic strategy of defect engineering and compositing with a calabash carbon matrix to reduce Zn2+ diffusion barriers and accelerate electron transfer. The VO2 cathode provided a high specific capacity at a low rate of 303 mA h g-1 at 0.1 A g-1 after 191 cycles, along with good rate performance (168 mA h g-1 at 10 A g-1) and satisfactory long-term stability (170 mA h g-1 at 1 A g-1 after 1100 cycles). The exhaustive structural analyses indicated that oxygen vacancies accelerated the Zn2+ diffusion rate, while a uniform calabash-like hollow carbon matrix improved electronic conductivity during cycling. Moreover, ex-situ measurements demonstrated that during discharge, the composite cathode transformed to layered Zn3+x(OH)2V2O7·2H2O, which then facilitated the subsequent intercalation of Zn2+. This cooperative strategy advances the practical application of aqueous zinc ion batteries by leveraging vanadium-based electrodes.

Hierarchical porous carbon materials for lithium storage: preparation, modification, and applications

Secondary battery as an efficient energy conversion device has been highly attractive for alleviating the energy crisis and environmental pollution. Hierarchical porous carbon (HPC) materials with multiple sizes pore channels are considered as promising materials for energy conversion and storage applications, due to their high specific surface area and excellent electrical conductivity. Although many reviews have reported on carbon materials for different fields, systematic summaries about HPC materials for lithium storage are still rare. In this review, we first summarize the main preparation methods of HPC materials, including hard template method, soft template method, and template-free method. The modification methods including porosity and morphology tuning, heteroatom doping, and multiphase composites are introduced systematically. Then, the recent advances in HPC materials on lithium storage are summarized. Finally, we outline the challenges and future perspectives for the application of HPC materials in lithium storage.