Lithio-Gel via Lithium Bonding: Mitigating Anode Failure by Blocking Crosstalk in Rechargeable Li-SOCl₂ Batteries

Li-SOCl₂ secondary batteries are promising energy storage systems due to their exceptional energy density and robust safety performance under a wide range of temperatures. However, their practical application is hindered by the crosstalk of cathode-derived species and electrolyte volatility, which leads to rapid anode deterioration, poor reversibility, and limited cell life. To address these issues, we present an in situ formed quasi-solid-state gel electrolyte mediated through a lithium bond (Li-bond), which effectively suppresses the detrimental crosstalk and electrolyte volatilization. This design is achieved through the limited dissociation of fluorinated lithium salts in SOCl₂, where the highly polarized additives promote the self-assembly of Li-bonding networks. Built upon the solvated chain-like structure of the conventional LiAlCl₄-SOCl₂ electrolyte, the Li-bonding promotes the formation of a stable lithio-gel electrolyte (LGE). Electrochemical tests demonstrate that the LGE mitigates the detrimental byproducts on Li deposits through restraining the crosstalk of cathode-derived species and significantly extends the cycle life of a limited Li anode (100 μm) at high areal capacities, maintaining a high areal capacity of 6 mAh cm^-2 at a current density of 5 mA cm^-2 for 60 cycles and achieving an active material capacity utilization of over 80% with 3000 mAh g^-1 capacity for 80 stable cycles, which further enhances the practicality (minimizing Li anode excess). These findings underscore that a deeper understanding of electrolyte design in Li-SOCl₂ systems can pave the way for a new paradigm of high energy density and longer-lasting rechargeable lithium metal batteries.