Regulating the Heat Generation Power of a LiNi_0.8Co_0.1Mn_0.1O₂ Cathode by Coating with Reduced Graphene Oxide

Heat generation, accumulation, and runaway severely affect the practical applications of lithium-ion batteries (LIBs) using Ni-rich Ni/Co/Mn ternary cathode materials. In principle, the aforementioned thermal characteristics of a LIB are mainly determined by the heat generation power of the cathode and anode materials during charging/discharging. In this work, the heat generation power of the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material coated with and without reduced graphene oxide (rGO) is studied systematically. By coupling an electrochemical workstation with a multichannel microcalorimeter, the heat generation power of NCM811 under different charging/discharging conditions was measured on coin cells. Meanwhile, a theoretical model was also proposed to analyze the intrinsic factors of the NCM811 that possibly affect its heat generation power during electrochemical charging/discharging. The results show that the particle size, lithium-ion diffusion coefficient, specific heat capacity, thermal conductivity, and electric conductivity can all affect the heat generation power. Different from that, the particle size and the lithium-ion diffusion coefficient of NCM811 are the dominating factors. It is demonstrated further that by coating rGO onto NCM811, the lithium-ion diffusion coefficient of NCM811 is improved, and the heat generation power is reduced accordingly.