Modified MOF‐Based Composite All‐Solid‐State Polymer Electrolyte with Improved Comprehensive Performance for Dendrite‐Free Li‐Ion Batteries

Abstract Solid‐state polymer electrolytes (SPEs) used for Li‐ion batteries have consistently received widely−attention owing to its high safety, excellent flexibility, and good compatibility with electrodes. However, pristine SPEs are difficult to satisfy all necessary demands for the practical applications in high‐performance Li‐ion batteries. Herein, a polycaprolactone modified metal‐organic framework (MOF‐PCL) composite polymer electrolyte (CSPE) is fabricated through the facile UV‐light induced photopolymerization of boronic ester crosslinking monomer (BEM) and poly (ethylene glycol) diacrylate (PEGDA) in the presence of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and MOF‐PCL. The existence of MOF‐PCL in the electrolyte can not only obviously improve the ion conduction, but also enhance electrochemical stability simultaneously. Besides, the boron‐doped network structure can further promote the transport of Li‐ions. As a result, the obtained CSPE has a higher lithium‐ion transference number of 0.59 and a wide electrochemical window of 5.29 V. Moreover, the LiFePO 4 /Li cell based on this CSPE also exhibits excellent long‐cycling and rate performance. Undoubtedly, this study not only can provide a new designed method for SPEs with comprehensive performance, but also exhibits a good application potential of this modified MOF‐based CSPE with borate ester in the high‐performance Li‐ion batteries.