Severe interfacial side reactions of polymer electrolyte with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode and Li metal anode restrict the cycling performance of solid-state NCM811/ Li batteries.H erein, we propose ac hemically stable ceramicpolymer-anchored solvent composite electrolyte with high ionic conductivity of 6.0 10 À4 Scm À1 ,w hiche nables the solid-state NCM811/Li batteries to cycle 1500 times.T he Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 nanowires (LNs) can tightly anchor the essential N, N-dimethylformamide (DMF) in poly(vinylidene fluoride) (PVDF), greatly enhancing its electrochemical stability and suppressing the side reactions.W ei dentify the ceramic-polymer-liquid multiple ion transport mechanism of the LNs-PVDF-DMF composite electrolyte by tracking the 6 Li and 7 Li substitution behavior via solid-state NMR. The stable interface chemistry and efficient ion transport of LNs-PVDF-DMF contribute to superior performances of the solid-state batteries at wide temperature range of À20-60 8 8C.

The garnet electrolyte presents poor wettability with Li metal, resulting in an extremely large interfacial impedance and drastic growth of Li dendrites. Herein, a novel ultra-stable conductive composite interface (CCI) consisting of Li y Sn alloy and Li 3 N is constructed in situ between Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) pellet and Li metal by a conversion reaction of SnN x with Li metal at 300 8C. The Li y Sn alloy as a continuous and robust bridge between LLZTO and Li metal can effectively reduce the LLZTO/Li interfacial resistance from 4468.0 W to 164.8 W. Meanwhile, the Li 3 N as a fast Li-ion channel can efficiently transfer Li ions and give their uniform distribution at the LLZTO/Li interface. Therefore, the Li/LLZTO@CCI/ Li symmetric battery stably cycles for 1200 h without short circuit, and the all-solid-state high-voltage Li/LLZTO@CCI/ LiNi 0.5 Co 0.2 Mn 0.3 O 2 battery achieves a specific capacity of 161.4 mAh g À1 at 0.25 C with a capacity retention rate of 92.6 % and coulombic efficiency of 100.0 % after 200 cycles at 25 8C.

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