Zwitterion assisted in-situ grain boundary coating on Li-rich cathode boosting electrochemical performance in Li-ion batteries

Abstract

High-capacity and high-voltage Li-rich cathode materials are promising candidates for next-generation LIB cathodes due to their high energy density characteristics. However, they face challenges such as electrolyte side reactions at high voltages and slow kinetic properties. To overcome these challenges, this study proposed a one-pot Li₂WO₄ (LWO) grain boundary coating method. Additionally, a novel synthesis process utilizing zwitterions was introduced to uniformly position heavy tungsten on the surface of a cathode material. Through grain boundary coating, the cathode material was modified not only at the secondary particle level, but also between primary particles by filling grain boundaries with the coating compound. The synthesized LWO grain boundary coated Li-rich cathode exhibited significantly superior rate capability and cycle stability compared to the pristine material. Furthermore, it demonstrated a more stable cycling behavior after high-temperature storage than pristine counterpart. This study presents a primary particle surface modification technique through grain boundary coating and a one-pot synthesis process leveraging zwitterions as a new driving force, providing a new perspective for enhancing the performance of Li-rich cathode materials.