Enhancing the electrochemical performance of lithium-rich manganese-based layered oxides through the phosphorus-vanadium coating of single-crystalline particles

Abstract

Lithium-rich manganese-based cathode materials are considered next-generation cathode materials for high-energy-density lithium-ion batteries. However, their practical application is limited by continuous voltage decay, poor cycle stability, and inferior rate performance. In this study, single-crystalline Li1.2Ni0.13Co0.13Mn0.54O2 (LNCMO) with different coating levels of Li3V2(PO4)3 was synthesized using the sol-gel method, moreover, a spinel phase and oxygen vacancies were induced between the bulk material and coating layer during the coating process. This modification strategy can effectively suppress voltage decay, improve the rate performance, and reduce side reactions between the active materials and electrolytes during cycling. These results showed that the Li+ ion diffusion coefficient of the LNCMO electrode modified with 3 wt% phosphorus-vanadium is 52 times that of the original sample. The 3 wt% phosphorus-vanadium modified LNCMO delivers a capacity of 201.4 mA h g−1 at 1C rate and retains 176.4 mA h g−1 (87.7% retention) after 100 cycles at 1C, while the pristine material only displayed 72.2% retention under identical conditions. Furthermore, the average discharge midpoint voltage decay of pristine LNCMO (2.4 mV per cycle) decreased to 1.9 mV per cycle. These results provide insights into the future application of lithium-rich manganese-based materials.