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

Abstract

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 LiNi 0.8 Co 0.1 Mn 0.1 O 2 (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. KEYWORDS: heat generation power, LiNi 0.8 Co 0.1 Mn 0.1 O 2 , cathode, lithium-ion diffusion coefficient, reduced graphene oxide

Heat Generation Power of the LiNi0.8Co0.1Mn0.1O2 Cathode at Higher Charging Cutoff Voltages

“…Predictably, increasing the cutoff voltage for charging should affect the heat generation power of NCM811. To elaborate the assumption, by coupling a calorimeter (TAM Air) with a LAND-CT2001A electrochemical workstation, 43 generation power is calculated following the equations proposed by Song et al, 22,44 and the results are summarized in Figure 1b. With the charging cutoff voltage increasing, the heat generation power increases.…”

“…In our previous study, we demonstrated that the particle size, electric conductivity, and lithium-ion diffusion coefficient of NCM811 could all affect its heat generation power during charge/discharge procedures. 43 Herein, these internal parameters of NCM811 before and after 205 cycles under charging cutoff voltages of 4.3, 4.5, and 4.8 V were also characterized. Figure S4 shows the FE-SEM image of NCM811 electrodes before and after 205 cycles under different charging cutoff voltages.…”

“…Predictably, increasing the cutoff voltage for charging should affect the heat generation power of NCM811. To elaborate the assumption, by coupling a calorimeter (TAM Air) with a LAND-CT2001A electrochemical workstation,43 the heat flow of the NCM811 cathode at various charge/discharge cycles under different charging cutoff voltages was measured in situ. As shown in Figures S1−S3, all heat flow curves show obvious exothermic peaks during charge and discharge.…”

Two-dimensional graphitic carbon-nitride (g-C3N4)-coated LiNi0.8Co0.1Mn0.1O2 cathodes for high-energy-density and long-life lithium batteries

“…Protective particle coatings, mainly including metal oxides, [10][11][12][13] oxide solid electrolytes, [14][15][16] phosphates, [6,17,18] fluorides, [19][20][21][22] or graphene, [23][24][25] were widely utilized to address these problems. For example, Xu et al [26] used Al 2 O 3 and Zhou et al [10] utilized ZnO.…”