Moisture-scavenging electrolyte for high-temperature stable lithium-ion batteries

Abstract

High-temperature induced battery failure has emerged as a critical barrier to its large-scale application, because of the acceleration of the reaction between LiPF₆ and trace water in electrolyte, producing hydrogen fluoride (HF) that damages electrode interfaces/materials and drives rapidelectrode degradation fading. To fundamentally address this issue, we propose a three-pronged electrolyte additive of 3-Isocyanatopropyltrimethoxysilane (IPTOS), which achieves original water scavenging with the isocyanate (-NCO) moieties, directly intercepting HF formation at its origin. Further, it modulates the Li⁺ solvation structure by promoting PF₆⁻coordination, facilitating the formation of an inorganic-rich SEI that enhances graphite performance. Simultaneously, its Si-containing components preferentially decompose on the cathode, enabling a robust gradient LiF-silicate-rich CEI, suppressing transition metal dissolution. This synergistic protection empowers high-loading NCM811 (LiNi_0.8Co_0.1Mn_0.1O₂) ||Gr(graphite) full cells to achieving 79.98 % capacity retention after 200 cycles at 0.5 C and 55℃, outperforming conventional electrolytes. Notably, the system maintains 74.22 % capacity after 100 cycles even under 4.5 V operation, demonstrating unprecedented high-voltage thermal stability. This successful investigation of multifunctional IPTOS presents a promising multi-in-one strategy for additive design, espacially providing a new thoughts to improve the high temperature performance of Ni-rich cathode in lithium-ion batteries.