Boosting high-rate lithium storage in Li3VO4via a honeycomb structure design and electrochemical reconstruction

Abstract

While the intrinsic safety and capacity merits of Li₃VO₄ endow it with great promise in LIBs, the moderate lifespan under a high rate hinders its practical application. Herein, we demonstrate for the first time, the boosting of an unprecedented high-rate performance of the Li₃VO₄-based electrode via a novel honeycomb architecture design and its electrochemical reconstruction upon cycling. Li₃VO₄/C honeycombs (LVO/C Hs) consisting of primary carbon-coated Li₃VO₄ nanoparticles have been constructed by a self-assembly strategy, through a developed electrospraying approach using polyvinyl alcohol as a morphology regulator. In the LVO/C Hs, the local LVO@C nanoparticle constituents render high activity, and the integral honeycomb-like architecture facilitates electron transfer and promotes a synergistic effect between the constituents. The lithiation-driven electrochemical reconstruction in cycling ensures the integrity of the honeycomb structure, and at the same time, the LVO nanoparticles are refined to 3–5 nm, producing abundant nanopores. The self-reconfigured structures with ultrasmall nanoparticles and large void space effectively shorten the ion diffusion pathway. The above structural characteristics trigger a continuous high capacitive charge storage, giving rise to unprecedented high-rate performance. The LVO/C Hs electrode delivered a discharge capacity recovery of 590.0 mA h g⁻¹ at 0.5 A g⁻¹ after 6 periodic rate performance tests from 0.5 to 10 A g⁻¹ over 430 cycles. When cycling at a high discharge current of 6 A g⁻¹, the LVO/C Hs electrode could maintain stable cycling over 14 000 cycles with a high discharge capacity of 324.5 mA h g⁻¹. The lifespan of the LVO/C Hs is the longest among all the reported LVO-based electrodes, demonstrating great potential in long-life and high-rate applications such as electric vehicles and power stations.