Ceramic‐Induced Polymer Reconstruction to Promote Li ⁺ Migration in Electrolyte and Interphase Layers of Solid‐State Lithium Batteries

Abstract Ceramic‐polymer composite electrolytes are promising in developing solid‐state lithium batteries (SLBs), but the synergy between the ceramic and polymer is limited to “physical” promotion in mechanical and ion‐conductive properties of the electrolytes. Herein, a garnet‐type ceramic electrolyte is introduced into a semi‐interpenetrating network polymer electrolyte (sIPNE), comprising a poly(ethylene oxide) (PEO)‐based network and poly(vinylidene fluoride) (PVdF)‐based chains, to form gn‐IPNE with full‐interpenetrating networks of the PEO and PVdF embedded with salt lithium bis(fluorosulfonyl)imide (LiFSI) and permanent solvent dimethylacetamide (DMAc) in [Li ⁺ (DMAc) _x ]. The Li ⁺ ‐transport proceeds with hopping‐diffusion along the ether‐linkages on the PEO and the FSI ⁻ ‐clusters on the PVdF. The added garnet‐ceramic activates DMAc to mediate crosslinking of the PVdF‐chains and forming β‐PVdF that facilitate Li ⁺ diffusion. The PVdF crosslinking helps disperse the FSI ⁻ ‐clusters to facilitate Li ⁺ ‐transport and to form robust LiF and Li ⁺ ‐conductive Li ₃ N in the interphases. Additionally, the garnet‐ceramic helps direct Li ⁺ ‐transport for facile charge–discharge of SLBs. The synergistic design for ceramic‐polymer composite electrolytes, leveraged by the ceramic‐polymer‐solvent interactions, achieves ionic conductivity of 1.9 mS cm ⁻¹ and Li⁺‐transference of 0.68 at 30 °C. The resulting SLBs present excellent charge–discharge stability of 86% retention over 500 cycles in Li||LiFePO ₄ and 90% over 200 cycles in Li||LiNi _0.8 Mn _0.1 Co _0.1 O ₂ .