PI-LATP-PEO Electrolyte with High Safety Performance in Solid-State Lithium Metal Batteries

Although lithium metal is extensively used as an anode material for next-generation secondary batteries, the lithium metal reacts with the commonly used organic electrolytes, forming lithium dendrites, resulting in short-circuiting of batteries, which is a safety hazard. Solid-state electrolytes are a feasible solution to overcome these limitations. We prepared a PI–PEO–LATP composite solid electrolyte by compounding poly­(ethylene oxide) (PEO) and Li1.4Al0.4Ti1.6(PO4)3 (LATP) with an electrospun polyimide (PI) nanofiber membrane using a solution-casting method. The best electrochemical and battery performance was obtained when the ratio of LATP to PEO was 15%. LATP reduces the crystallinity of PEO and increases its ionic conductivity. The 3,3′,4,4′-biphenyltetracarboxylic dianhydride-4,4′-oxydianiline PI nanofibrous membrane exhibited enhanced thermal stability and self-extinguishing performance. The lithium symmetric battery assembled with the PI–PEO–LATP composite solid electrolyte functioned stably for 1000 h at a current density of 0.5 mA·cm–2. The solid electrolyte showed good compatibility with a lithium metal anode and could inhibit the growth of lithium dendrites. When using the LiNi0.8Co0.1Mn0.1O2 positive electrode and lithium metal negative electrode, the assembled coin cell maintained a discharge capacity of 170.7 mAh·g–1 after 100 cycles at 0.2 C, with a capacity retention rate of 95% and Coulombic efficiency of approximately 100%.