1. Schematic diagram of PP separator coated by LLZTO

2. Structural characterization of PP-10 μm-LLZTO separator(a) XRD patterns of LLZTO powder, bare PP separator, PVDF and PP-10 μm-LLZTO separator; (b) Optical photos of PP-10 μm-LLZTO separator; (c) Photograph of LLZTO-PVDF slurry after stirring; (d) SEM image of LLZTO powder; (e) Cross-sectional SEM image of PP separator; (f) Top-view and (g) cross-sectional SEM images of PP-10 μm-LLZTO separator; Electrolyte contact angles of (h) PP and (i) PP-10 μm-LLZTO separators

3. Electrochemical performance of Li-Si/C half cells(a) CV curves of the initial 5 cycles of half-cell using PP-10 μm-LLZTO separator; (b) Rate tests of half-cells using PP and PP-10 μm-LLZTO separators; (c) Charge-discharge curves of Li/Si half-cell using PP-10 μm-LLZTO separator; (d) Stability tests of Li/Si half-cells using PP and PP-10 μm-LLZTO separators with different thicknesses; (e) EIS spectra of half-cells with PP and PP-10 μm-LLZTO separators before cycling. Colorful figures are available on website

S1. (a) SEM image and corresponding EDS elemental mapping of Si/C particles, (b) EDS spectrum of Si/C particles

S2. Charge-discharge curves of Li-Si/C half-cell using PP separator

S3. Cross-sectional SEM images of PP-6 μm-LLZTO separator

S4. Cross-sectional SEM images of PP-12 μm-LLZTO separator

S5. Stability test of Li-Si/C half-cell using PP-PVDF separator

S6. (a) Top-view and (b) cross-sectional SEM images of the Si/C anode of the Li|PP-10 μm-LLZTO|Si/C half-cell after 10 cycles

S7. Cross-sectional SEM images of (a) Si/C anode, (b) PP-10 μm-LLZTO separator, (c) Si/C anode, (d) PP-10 μm-LLZTO separator after charge

S8. Equivalent circuit model of bare PP half-cell and PP-10 μm-LLZTO half-cell

S9. (a, c) C1s and (b, d) F1s for SEI of the half-cells with (a, b) PP and (c, d) PP-10 μm-LLZTO separators after 100 cycles

S10. CV curves of initial 3 cycles of the LFP|PP-10 μm-LLZTO|Si/C full cell

S11. (a) Charge-discharge curves during cycling of LFP|PP-10 μm-LLZTO|Si/C at 0.3C; (b) Cycling performances of LFP|PP|Si/C and LFP|PP-10 μm-LLZTO|Si/C at 0.3C

S12. Charge-discharge curves of LFP|PP|Si/C full cell