Exploring High Li⁺ Transference Number Solid-State Electrolytes Based on a Poly(-caprolactone) Polymer Matrix with Efficient Lithium Salt Dissociation for Applications in Lithium-Metal Batteries

Composite polymer electrolytes (CPEs) with high securityand mechanicalflexibility are needed for all-solid-state lithium-metal batteries(LMBs). However, their practical application is hindered by the increasingdemand for high-power and high-areal-energy-density storage solutions.Herein, a high-powered CPE relying on poly(& epsilon;-caprolactone) (PCL)as the polymer matrix is developed. The binding energy of Li+-PCL is predicted to be -130.163 kcal & BULL;mol(-1) via density functional theory calculations, which implies a highdissociation of Li salts in the PCL matrix. The weak interactionsbetween the Li+ and the polymer chains enable the CPEswith a high Li+ transfer number (t (Li+)) of 0.71. Besides, LiFePO4//Li batteries delivera high capacity retention of 85% for over 600 cycles at 2.0C. Thiswork demonstrates the tremendous potential of PCL-based CPEs in promotingthe application of high-power-performance LMBs.