Bio-inspired in-situ CO2 foaming opens up rapid Li+ transport channels in quasi-solid polymer electrolytes for lithium-metal batteries

To overcome the limitation of Li + transport in conventional polymer electrolytes that heavily depends on segmental relaxation, we propose a strategy to construct multi-functional fast ion transport channels. Inspired by the fermentation process, we employed an in-situ carbon dioxide foaming technique to introduce a controlled volume of carbonic acid (H 2 CO 3 ) into the precursors of cellulose acetate (CA) and poly (vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP), thereby constructing a quasi-solid-state electrolyte with ordered porous fast ion transport channels via simple heating. The C O and -OH groups in CA facilitate lithium salt dissociation and promote Li + transport, while the electrolyte swelling resistance of PVDF-HFP preserves channel integrity. Density functional theory calculations demonstrate that carbonyl groups in CA effectively immobilize PF 6 − anions. Notably, the CPC400 electrolyte exhibits exceptional electrochemical performance, including a high ionic conductivity of 3.5 × 10 −3 S cm −1 at 30 °C and a high ion transference number of 0.73. Symmetric Li||Li cells with CPC400 achieve ultra-stable cycling for over 2100 h at 0.2 mA cm −2 . Furthermore, LCO||Li cells paired with high-voltage LiCoO 2 cathode cycle for 300 cycles at 0.2C with 98.8% capacity retention. This work provides a practical strategy for developing high-energy-density lithium metal batteries.