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

摘要

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 LiCoO2 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.