Integrated design of ultrathin crosslinked network polymer electrolytes for flexible and stable all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLBs) are promising power sources for flexible and wearable electronics due to their high energy density and reliable safety. Here, we reported the novel design of an ultrathin crosslinked solid polymer electrolyte (SPE) with high ion conductivities at room temperature (RT), high mechanical strength, and fast interfacial charge transport for flexible ASSLBs. The SPE is synthesized by one-step in-situ crosslinked polymerization of 1, 3-dioxolane, and trimethylolpropane triglycidyl ether within a lithium nitrate-containing mesoporous polymer (LP) matrix. The three-dimensional crosslinked polymer network enables the composite SPE with high RT ionic conductivity of 3.0 × 10−4 S cm−1 and improved oxidation stability. The LP matrix could promote the formation of hybrid Li3N/LiF interfacial layers on both sides of the SPE, resulting in uniform lithium deposition. The symmetric cell of Li/SPE/Li can be cycled with an extremely small overpotential of 45 mV for 1000 cycles. The integrated paper-type pouch cell could retain high capacities retention (>90%), negligible voltage fluctuation (<50 mV), and high operation safety during 2000 cycles of bending (bending radius: 5 mm). This work offers a feasible pathway for developing an ultrathin solid-state electrolyte with high ionic conductivities, excellent interfacial compatibility, and high mechanical robustness for flexible ASSLBs.