LiDFOB-Regulated interfacial chemistry enables high-coulombic-efficiency elastomeric electrolytes for lithium metal batteries

The application of lithium-metal batteries (LMBs) has been hindered by dendritic deposition, low coulomb efficiency (CE) and significant volume changes during repeated plating/stripping process. Herein, we developed an elastomeric quasi-solid electrolyte (QSE) through in-situ polymerization method with a tailored composition. The incorporation of difluoro(oxalato)borate (LiDFOB) facilitated the generation of a uniform lithium deposition morphology and significantly enhanced the CE of LMB. Remarkably, the Li/Cu cell exhibited a high CE of 98.33 % compared to the battery without LiDFOB (97.09 %). Moreover, the Li/Li symmetric cell demonstrated long-term cycling stability about 600 h at 0.3 mA cm −2 for 0.3 mAh cm −2 . The Li/LiFePO 4 (LFP) cell displayed an initial discharge capacity of 144.2 mAh g −1 at 1 C, with a capacity retention of 98.54 % after 400 cycles. Additionally, the average CE over 400 cycles was improved to 99.93 %. Density functional theory (DFT) calculations revealed that Slab-DFOB − -Li + has a lower binding energy, enabling LiDFOB to preferentially absorb and react on the lithium metal surface, thereby facilitating smooth and dendrite-free lithium deposition. The incorporation of functional LiDFOB into elastomeric QSE effectively enhances the electrochemical performance of LMBs. The compatible modification strategy provides a new perspective for improving the performance of elastomeric electrolytes.