Enhanced interfacial stability via Li+ coordination regulated block copolymer electrolytes for solid-state lithium metal batteries

Solid polymer electrolytes (SPEs) are promising for solid-state lithium metal batteries (SSLMBs), but their practical performance remains constrained by insufficient ionic conductivity and sluggish Li + transport. Herein, polyimide (PI) was incorporated into poly(ether-block-amide) (Pebax) to construct a free-standing Pebax-PI SPE. Hydrogen bonding interactions between PI and Pebax regulated the Li + coordination environment and promoted lithium salt dissociation, while the imide groups of PI provided additional coordination sites for Li + transport. The optimized Pebax-PI SPE exhibited an ionic conductivity of 2.0 × 10 −4 S cm −1 , a Li + transference number of 0.56, and an electrochemical stability window of 4.7 V, while maintaining good mechanical strength (19.40 MPa) and thermal stability. Li//Li symmetric cells showed a low polarization voltage of about 20 mV and stable cycling for over 400 h without obvious Li dendrite growth. Furthermore, Li//LFP cells exhibited improved electrochemical performance, retaining approximately 83% of their initial capacity after 300 cycles at 0.5 C and maintaining a reversible capacity of about 80 mAh g −1 after 200 cycles at 1.0 C. The Pebax-PI SPE provides a strategy for regulating Li + transport and stabilizing Li metal interfaces in SSLMBs.