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

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.