Heat Generation Behavior of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathodes under Varying Cycling Conditions and Material Configurations

Abstract

The temperature of lithium-ion batteries (LiBs) significantly impacts cell performance, cycle life, and safety. Effective thermal management and cooling systems require a detailed understanding of heat generation within battery cells, which strongly depends on the specific materials used. Particularly, lithium-nickel-manganese-oxide (LNMO) is a promising cathode candidate for next-generation LiBs, because of its cobalt-free composition and high operating voltage (∼4.7 V vs. Li/Li). This study systematically investigates various factors influencing heat generation in LNMO cathodes. Initially, the impact of charging and discharging currents on heat generation was examined, revealing that heat generation during charging is lower than during discharging. As a result, charging currents 1.58 times higher than the discharging currents can be achieved while maintaining similar maximum heat fluxes. Subsequently, the effects of material additives and temperature variations were investigated. The results show that an optimization of the material combination can reduce the maximum heat flux peaks of LNMO cathodes by approximately 30% at 25 °C and about 20% at 45 °C. Furthermore, the analysis demonstrates that 35-55% of the total heat is generated at State of Charge (SoC) below 20%, highlighting a significant potential for thermal improvement in LNMO cathodes particularly within the low SoC range.