Effect of Additives With Phenyl and Acid Anhydride Functional Groups on the Wide Temperature Operation Performance of LiNi_0.8Co_0.1Mn_0.1O₂||SiO/Graphite Pouch Cells

ABSTRACT High‐nickel LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode paired with silicon‐based graphite (SiO/Gr) is pivotal for enhancing the energy density of lithium‐ion batteries (LIBs). However, the high reactivity of NCM811 with the electrolyte and the volumetric expansion issues associated with SiO/Gr pose significant challenges to their practical application. To settle these issues, we explore the impact of additives with phenyl and acid anhydride moieties on the performance of NCM811‖SiO/Gr pouch cells across a wide temperature range of −20°C~60°C. Acid anhydride additives are capable of diminishing the internal resistance in NCM811‖SiO/Gr pouch cells, as well as curbing gas evolution and thickness increase during the operational phase. Notably, the batteries enriched with citraconic anhydride (CAn) and succinic anhydride (SAn) additives after 120 cycles at 45°C demonstrated enhanced capacity retention from 83.2% to 88.1% and 85.5%, respectively. Intriguingly, the inclusion of phenyl‐containing additives in the electrolyte was found to be advantageous for NCM811‖SiO/Gr pouch cells' low‐temperature performance. Furthermore, neither type of functional group significantly enhanced performance at room conditions. Consequently, the combination of additives is necessary to fulfill the stringent requirements of LIBs for extreme environment applications. This work guides designing composite electrolytes for high energy density wide temperature operation LIBs.