Chlorinated‐Solvent‐Based Electrolyte for Safe and Stable Lithium Battery Chemistry

Abstract The current lithium battery technology is greatly limited by safety concerns. Fluorinated and organophosphorus solvents can reduce the electrolyte flammability. However, these solvents are not fire‐retardant efficiently for lithiated anodes. Here, for the first time, we report an all‐chlorinated‐solvent design strategy to enable electrolytes with durability, non‐flammability and fire‐proof. We demonstrate that the premature battery failure in chlorinated ether electrolytes is mainly caused by the low anode compatibility and aluminum current collector corrosion originating from the dissolution of LiCl‐rich solid electrolyte interphase, which can be efficiently overcome by interphase regulation via film‐forming chlorinated carbonate and promoted anion reduction. These insights were applied to graphite||LiFePO 4 full cells, which presented high capacity retention together with promising safety assurance under thermal, electrical and mechanical abuse conditions, outperforming traditional electrolytes. We also applied the as‐developed fire‐proof electrolytes to 4.4 V high‐loading Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 cells and attained durable cycling features without current collector corrosion. This work provides the design criteria for developing fire‐retardant electrolytes for highly safe lithium batteries.