Affiliation:
1. School of Materials Science & Engineering Beihang University Beijing 100191 China
2. Department of Chemistry National University of Singapore 3 Science Drive 3 117543 Singapore
3. Department of Materials Science and Engineering. National University of Singapore 7 Engineering Drive 1 Singapore 117574 Singapore
4. Joint School of National University of Singapore and Tianjin University International Campus of Tianjin University, Binhai New City Fuzhou 350207 P. R. China
5. Department of Physics National University of Singapore 2 Science Drive 3 117542 Singapore
Abstract
AbstractA critical challenge in solid polymer lithium batteries is developing a polymer matrix that can harmonize ionic transportation, electrochemical stability, and mechanical durability. We introduce a novel polymer matrix design by deciphering the structure‐function relationships of polymer side chains. Leveraging the molecular orbital‐polarity‐spatial freedom design strategy, a high ion‐conductive hyperelastic ternary copolymer electrolyte (CPE) is synthesized, incorporating three functionalized side chains of poly‐2,2,2‐Trifluoroethyl acrylate (PTFEA), poly(vinylene carbonate) (PVC), and polyethylene glycol monomethyl ether acrylate (PEGMEA). It is revealed that fluorine‐rich side chain (PTFEA) contributes to improved stability and interfacial compatibility; the highly polar side chain (PVC) facilitates the efficient dissociation and migration of ions; the flexible side chain (PEGMEA) with high spatial freedom promotes segmental motion and interchain ion exchanges. The resulting CPE demonstrates an ionic conductivity of 2.19×10−3 S cm−1 (30 °C), oxidation resistance voltage of 4.97 V, excellent elasticity (2700 %), and non‐flammability. The outer elastic CPE and the inner organic–inorganic hybrid SEI buffer intense volume fluctuation and enable uniform Li+ deposition. As a result, symmetric Li cells realize a high CCD of 2.55 mA cm−2 and the CPE‐based Li||NCM811 full cell exhibits a high‐capacity retention (~90 %, 0.5 C) after 200 cycles.
Funder
Ministry of Education - Singapore
China Scholarship Council
National Research Foundation Singapore