Built-in elasticity-rigidity balanced polymer electrolyte in solid-state Li-batteries with high-loading cathode

Solid-state lithium batteries (SSLBs) using polymer electrolytes have attracted increasing attention owing to their intrinsic flexibility and high energy density . However, due to the lack of permeability like liquid electrolytes, polymer electrolytes equipped with high-loading electrodes are usually limited by the high polarization and rapid capacity decay. Herein, an elasticity-rigidity balanced polymer electrolyte (ERBE) was designed by the in-situ crosslinking polymerization, where poly(ethylene glycol) diacrylate (PEGDA) works as crosslinking elasticity agents, poly(vinylidene carbonate) (PVC) acts as main structure support. Benefiting from the structural design, ERBE electrolyte features high compression strength of 96.1 MPa and volume compression ratio up to 73.9 %. The ERBE also exhibits room-temperature ionic conductivity of 2.31 × 10 −4 S cm −1 and high Li-ions transfer number of 0.69. The LiFePO 4 ||Li cells equipped with ERBE electrolyte can maintain over 3000 cycles with 70.1 % capacity retention at 1 C and 25 °C. Even at the cathode mass loading up to 78 mg cm −2 , it can deliver a high discharge capacity of 11.98 mAh cm −2 at 25 °C. Such an integrated in-situ polymer electrolyte provides strong support for solving the problems of rigidity or elasticity insufficiency and dendrite growth, and holds promising applications in wide-temperature, high-energy-density solid-state batteries . • Design of polymer structures to achieve the balance between elasticity and rigidity . • Low glass transition temperature allows ERBE to operate smoothly at -20-60 °C. • The in-situ ion transport network ensures fast Li-ion mobility within the thick cathode. • Elasticity-rigidity balanced electrolyte matched with ultra-high loading cathode up to 78 mg cm −2 .