Carbon coating enhances electrochemical performance of LiNi0.8Mn0.2O2 assisted by dopamine hydrochloride

Abstract

Due to their ultrahigh specific energy density, Ni-rich cobalt-free layered oxides are regarded as promising cathode materials for next-generation lithium-ion batteries (LIBs). However, as the nickel content increases, serious structural degradation during the cycling process can lead to a rapid decrease in capacity. This work aims to prepare a carbon layer coating on the surface of LiNi_0.8Mn_0.2O₂ cathode by dopamine hydrochloride using solid-state sintering method. The crystal structure, micro-morphology and electrochemical performance have been studied. This surface carbon coating strategy effectively suppresses the generation of surface side reactions on material particles, improves the electrochemical performance of the cathode in comparison with the original material NM. The optimized sample (NM@NC-0.2) shows a high specific capacity of 205.1 mAh g^− 1 at 0.5 C, along with a capacity retention of 93% after 100 cycles under the same current density. In situ EIS showed that this modification method significantly reduced the electrochemical impedance of the cathode surface, further enhancing the electron/Li⁺ diffusion ability.