Boosting a practical lithium carbon dioxide battery through a decoupled electrolyte

Highly conductive electrolytes and stable electrolyte|electrode interfaces are desired for next-generation batteries. Constructing solid-electrolyte interphases on electrodes is a prevailing strategy for enhancing interfacial stability but fails to prevent inevitable breakdown and reformation of interphases during prolonged cycling. Herein, a decoupled electrolyte is designed by introducing a co-solvent (tetraethylene glycol dimethyl ether) with high stability and high positive electrostatic potential values into highly conductive dimethylformamide-based electrolytes, which suffer from electrolyte|positive electrode instability. The preferential adsorption of cations solvated with co-solvents on the positive electrode during discharge induces the formation of a co-solvent-rich localized environment, inhibiting side reactions and contributing to long cyclability. Meanwhile, dimethylformamide in the bulk electrolyte helps to maintain high ionic conductivity, thus improving kinetics. Notably, lithium-carbon dioxide cells with this decoupled electrolyte demonstrate a significantly improved cycle life of ~ 2600 hours and a low overpotential of ~ 1 V, even with a metal-free commercial reduced graphene oxide catalyst. Our work provides an alternative strategy to solid-electrolyte interphase construction for stabilizing electrolyte|electrode interface and unlocks the potential of previously underexplored solvents in batteries. Electrolyte|electrode instability largely limits battery lifespan of lithium-carbon dioxide batteries. Here, authors design a decoupled electrolyte system that enables long-term cycling and low overpotential in Li-CO2 batteries by regulating solvation structures near the positive electrode during dynamic cycling.