High-performance room temperature solid-state lithium battery enabled by PP-PVDF multilayer composite electrolyte

Solid-state batteries (SSBs) with thermal stable solid-state electrolytes (SSEs) show intrinsic capacity and great potential in energy density improvement. SSEs play critical role, however, their low ionic conductivity at room temperature and high brittleness hinder their further development. In this paper, polypropylene (PP)-polyvinylidene fluoride (PVDF)-Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP)-Lithium bis(trifluoromethane sulphonyl)imide (LiTFSI) multi-layered composite solid electrolyte (CSE) is prepared by a simple separator coating strategy. The incorporation of LATP nanoparticle fillers and high concentration LiTFSI not only reduces the crystallinity of PVDF, but also forms a solvation structure, which contributes to high ionic conductivity in a wide temperature. In addition, using a PP separator as the supporting film, the mechanical strength of the electrolyte was improved and the growth of lithium dendrites are effectively inhibited. The results show that the CSE prepared in this paper has a high ionic conductivity of 6.38×10 –4 S/cm at room temperature and significantly improves the mechanical properties, the tensile strength reaches 11.02 MPa. The cycle time of Li/Li symmetric cell and Li/LFP full cell assembled by CSE at room temperature can exceed 800 h, and the specific capacity of Li/LFP full cell can still reach 120 mAh/g after 800 h cycle at 2 C. This CSE has good cycle stability and excellent mechanical strength at room temperature, which provides an effective method to improve the performance of solid electrolytes under moderate condition. A PP-PVDF multilayered composite solid-state electrolyte (SSE) with high-concentration lithium salt and LATP fillers was successfully fabricated, which shows high ionic conductivity and mechanical strength. The designed SSE is demonstrated not only suppressing lithium dendrites, but also enable high specific capacity and long durable cycling at room temperature.