Polymer‐Clay Nanocomposite Solid‐State Electrolyte with Selective Cation Transport Boosting and Retarded Lithium Dendrite Formation

Abstract Commercialized lithium‐ion batteries (LIBs) with a liquid electrolyte have a high potential for combustion or explosion. The use of solid electrolytes in LIBs is a promising way to overcome the drawbacks of conventional liquid electrolyte‐based systems, but they generally have a lower ionic conductivity and lithium ion mobility. Here, a UV‐crosslinked composite polymer‐clay electrolyte (U‐CPCE) that is composed of a durable semi‐interpenetrating polymer network (semi‐IPN) ion transportive matrix (ETPTA/PVdF‐HFP) and 2D ultrathin clay nanosheets that are fabricated by a one‐step in situ UV curing method, are reported. The U‐CPCE exhibits robust and flexible properties with an ionic conductivity of more than 10 −3 S cm −1 at room temperature with the help of exfoliated clay nanosheets. As a result, the U‐CPCE‐based LIBs show an initial discharge capacity of 152 mAh g −1 (at 0.2 C for a LiCoO 2 half‐cell), which is comparable to that of conventional liquid electrolyte‐based cells. In addition, they show excellent cycling performance (96% capacity retention after 200 cycles at 0.5 C) due to a significantly enhanced Li + transference number ( t Li+ = 0.78) and inhibition of lithium dendrite formation on the lithium metal surface. Furthermore, a molecular dynamics (MD) study is conducted to elucidate the mechanism of improving ionic conductivity. The U‐CPCE design can offer opportunities for future all‐solid‐state Li‐ion batteries.