High-capacity all-solid-state lithium battery with stable interfaces enabled by ultra-thin polyvinylidene fluoride/Li3InCl6 composite solid electrolyte

The practical application of all-solid-state lithium batteries (ASSLBs) is inhibited by the poor ionic conduction of solid electrolytes and the large interfacial resistance in ASSLBs. To solve these issues, a simple sol-gel and coating process is developed to prepare self-standing ultra-thin composite solid electrolytes with polyvinylidene fluoride (PVDF) as the matrix and Li3InCl6 (LIC) as the inorganic filler. The introduction of LIC can effectively reduce the crystallinity of PVDF, provide new Li+ migration channels and enhance the ion conductivity of the electrolyte. The flexible PVDF matrix can improve the interfacial contact between the electrolyte and electrodes to promote uniform Li deposition. The constructed PVDF/LIC electrolyte not only reduces the interface impedance but also produces good mechanical strength to inhibit the growth of lithium dendrites, thus exhibiting good electrochemical performance. The assembled Li|PVDF/LIC-15%|LiFePO4 ASSLBs have a high capacity of 161.8 mAh g−1 with a capacity retention of 82.8% after 200 cycles. In addition, the PVDF/LIC electrolyte can be assembled with the high-voltage cathode (NCM811) to form ASSLBs. The proposed preparation method is simple, safe, and has good practical application prospects.