Flame-retardant Cl-substituted electrolyte for low-temperature and high-voltage lithium-ion batteries with fast interfacial kinetics

Carbonate electrolytes such as ethylene carbonate and dimethyl carbonate are excellent at stabilizing the graphite (Gr) anode and thus enable the unprecedented success of lithium-ion batteries but suffer from high flammability and slow ion-transport kinetics at low temperature. Here, we propose a chlorine atom substitution strategy to address the long-standing challenge of carbonate-based electrolytes. Cl atom substitution with an electron-withdrawing effect can facilitate the interfacial reaction by weakening the interactions with Li⁺ and forming a solid electrolyte interphase involving LiCl, as well as terminating the chain reaction of combustion when releasing Cl radicals. At a conventional salt concentration (1 M), the Cl-substituted carbonate electrolyte achieves stable operation of the LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode at a high cut-off voltage (4.6 V) and low-temperature adaptation towards the Gr anode (91.9% capacity retention at -20°C). The Ah-level Gr/NCM811 pouch cell maintains 84.6% capacity retention over 300 cycles and can enable the rigorous nail penetration short-circuit test at a fully charged state. This work provides a promising approach to build cost-efficient electrolytes for safe and energy-dense lithium-ion batteries with wide-temperature application potentials.