Suppressing Interfacial Side Reactions of Anode‐Free Lithium Batteries by an Organic Salt Monolayer

Abstract

AbstractAnode‐free lithium (Li) batteries are attractive owing to their high energy density. However, Li loss by forming solid‐electrolyte interphase (SEI) during cell activation leads to a ≈25% capacity decrease, and the capacity constantly fades upon cycling due to the side reactions on the copper (Cu) current collector. This paper reports high‐initial‐efficiency, long‐cycle‐life, and long‐calendar‐life anode‐free Li batteries by using an organic Li salt monolayer bonded on Cu. The functional salt, namely lithium ((4‐carbamoylphenyl)sulfonyl)(fluorosulfonyl)imide, electrochemically decomposes and passivates the Cu surface, which reduces Li sacrifice by SEI formation and suppresses galvanic Li corrosion and Li‐electrolyte reactions during cycling. This work records a LiF‐rich interphase on Cu and guided Li nucleation and growth. A 93.6% initial Li deposition efficiency is realized in a regular carbonate electrolyte, and the galvanic current is decreased to ≈40 nA cm−2, merely one‐tenth of bare Cu. After cell activation, 95.2% capacity is retained for a Cu|LiNi0.8Mn0.1Co0.1 pouch cell with a theoretical capacity of 200 mAh, and the cell is operated over 600 cycles. Calendar aging showed no damage to cell performance.