Thin, Deformable, and Safety‐Reinforced Plastic Crystal Polymer Electrolytes for High‐Performance Flexible Lithium‐Ion Batteries

A new class of highly thin, deformable, and safety‐reinforced plastic crystal polymer electrolytes (N‐PCPEs) is demonstrated as an innovative solid electrolyte for potential use in high‐performance flexible lithium‐ion batteries with aesthetic versatility and robust safety. The unusual N‐PCPEs are fabricated by combining a plastic crystal polymer electrolyte with a porous polyethylene terephthalate (PET) nonwoven. Herein, the three‐dimensional reticulated plastic crystal polymer electrolyte matrix is formed directly inside the PET nonwoven skeleton via in‐situ UV‐crosslinking of ethoxylated trimethylolpropane triacrylate (ETPTA) monomer, under co‐presence of plastic crystal electrolyte. The PET nonwoven is incorporated as a compliant skeleton to enhance mechanical/dimensional strength of N‐PCPE. Owing to this structural uniqueness, the N‐PCPE shows significant improvements in the film thickness and deformability with maintaining advantageous features (such as high ionic conductivity and thermal stability) of the PCE. Based on structural/physicochemical characterization of N‐PCPE, its potential application as a solid electrolyte for flexible lithium‐ion batteries is explored by scrutinizing the electrochemical performance of cells. The high ionic conductance of N‐PCPE, along with its excellent deformability, plays a viable role in improving cell performance (particularly at high current densities and also mechanically deformed states). Notably, the cell assembled with N‐PCPE exhibits stable electrochemical performance even under a severely wrinkled state, without suffering from internal short‐circuit failures between electrodes.