Cyano-Enriched Auxiliary Salts Mitigating Corrosion-Induced Crosstalk in Sulfonimide Salt Electrolytes toward Long-Life High-Safety Lithium Metal Batteries

Lithium sulfonimide salts have significantly advanced the development of lithium metal batteries (LMBs). Nevertheless, sulfonimide salt-based electrolytes exhibit severe corrosion behavior toward the aluminum (Al) current collector when exceeding 4.0 V (vs Li/Li+). Herein, the corrosion chemistry of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI)-based electrolytes in LMBs has been elucidated. It is revealed that, in addition to Al3+ dissolution, corrosion reactions also involve the Li anode, accompanied by decompositions of solvents. The corrosion byproducts, including Al3+ and a series of carbonate anions (e.g., CH3CH2OCO2–), will engage in crosstalk between electrodes to intensify the corrosion process. Herein, a series of cyano-group (−CN)-containing auxiliary salts are adopted to inhibit crosstalk effects by enabling strong anticorrosion coordination and interphase passivation. Encouragingly, the as-designed electrolyte enables the 468 Wh kg–1 LiNi0.8Co0.1Mn0.1O2||Li pouch cell to exhibit 80% capacity retention after 280 cycles. The as-designed electrolyte also mitigates exothermic reactions under thermal abuse, effectively delaying the thermal runaway.