Composite electrolyte with self-inserted structure and all-trans F conformation provides fast Li^(+)transport for solid-state Li metal batteries

Solid-state Li metal battery has attracted increasing interests for its potentiallyhigh energy density and excellent safety assurance, which is a promising candidatefor next generation battery system. However, the low ionic conductivityand Li^(+) transport number of solid-state polymer electrolytes limit their practicalapplication. Herein, a composite polymer electrolyte with self-insertedstructure is proposed using the layered double hydroxides (LDHs) as dopant toachieve a fast Li^(+) transport channel in poly(vinylidene-co-trifluoroethylene) [P(VDF-TrFE)] based polymer electrolyte. In such a composite electrolyte, P(VDF-TrFE) polymer has an all-trans conformation, in which all fluorineatoms locate on one side of the polymer chain, providing fast Li^(+) transporthighways. Meanwhile, the LDH can immobilize the anions of Li salts based onthe electrostatic interactions, promoting the dissociation of Li salts, therebyenhancing the ionic conductivity (6.4 × 10^(-4) S cm^(-1)) and Li^(+) transferencenumber (0.76). The anion immobilization effect can realize uniform electricfield distribution at the anode surface and suppress the dendritic Li growth.Moreover, the hydrogen bonding interaction between LDH and polymerchains also endows the composite electrolyte with strong mechanical properties.Thus, at room temperature, the Li jj Li symmetric cells can be stablycycled over 1000 h at a current density of 0.2 mA cm^(-2), and the full cells withLiFePO_(4) cathode deliver a high capacity retention (>95%) after 200 cycles. This work offers a promising route to construct solid-state polymer electrolytes withfast Li^(+) transport.