Improved Cycling Performance and High Rate Capacity of LiNi0.8Co0.1Mn0.1O2 Cathode Achieved by Al(PO3)3 Modification via Dry Coating Ball Milling

Abstract

LiNi0.8Co0.1Mn0.1O2 (NCM811) has attracted extensive attention as a promising cathode of lithium-ion batteries (LIBs) in next-generation electric vehicles, as the NCM811 sample possesses a high energy density and a price advantage. In this work, NCM811 was modified with an Al(PO3)3 precursor using the dry ball milling method followed by heat treatment to enable commercial development both at room temperature and a higher temperature. Compared with the unmodified NCM811 sample with the capacity retention of 68.70%, after Al(PO3)3 modification, the NCM811 sample heated to 500 °C exhibited a super capacity retention ratio of 93.88% after 200 charging–discharging cycles with the initial discharge capacity of 178.1 mAh g−1 at 1 C. Additionally, after Al(PO3)3 modification, the NCM811 sample heated to 500 °C showed much improved rate performance compared to bare NCM811 at the current density of 5 C. The enhanced electrochemical performance after cycling was due to the decreased charge transfer resistance and increased Li+ transmission, which were confirmed via electrochemical impedance spectra (EIS). The NCM electrodes showed improved structural stability as layered structures after Al(PO3)3 modification, consistent with the improved cycling performance. This work revealed that LiNi0.8Co0.1Mn0.1O2 material with phosphide coating can be constructed using a simple ball milling method, which is feasible for obtaining high-performance electrode materials.