A LLZO Fibers/ PPO polymeric matrix solid electrolyte for high voltage solid-state lithium batteries

Low ionic conductivity, narrow electrochemical window and poor mechanical property are the core problems that polymer solid electrolyte is difficult for practical application. Choosing suitable polymer and regulating the ion transport path through inorganic fillers is an important method to solve the above problems. Herein, a polymeric matrix composite solid electrolyte(CSE) was achieved by combining electrospun Li₇La₃Zr₂O₁₂ (LLZO) fibers and highly viscoelastic polypropylene oxide(PPO). The PPO matrix provides the CSE with good mechanical property to 56.75 MPa. While the addition of fibrous LLZO improves the ion transport channels of the CSE, which boosts the ionic conductivity, electrochemical window and ion transport number up to 4.59 × 10^− 4 S cm^− 1 at room temperature, 5.4 V and 0.74, respectively, when the content of LLZO fiber is 7.5 wt% of PPO polymer. The prepared PPO-LLZO fibers electrolyte can be used in high-voltage solid-state lithium battery and shows good rate and cycle performances. This composite solid electrolyte film and its simplified preparation conditions is beneficial for practical applications in solid-state batteries.