1. (a) Preparation process of NCM@cPAN powder, (b) schematic representation of as-prepared NCM@cPAN particle, and (c) schematic diagram of the solid-state NCM@cPAN+IL/PEO/Li cell

2. (a) FT-IR spectra of pristine PAN and PAN treated at 400 ℃, (b) schematic diagrams of pristine PAN and cPAN, and (c) Raman spectra of PAN, cPAN, NCM, and NCM@cPAN

3. (a) XRD patterns of NCM, NCM@PAN, and NCM@cPAN powders; SEM images of (b, c) NCM, (d, e) NCM@PAN, and (f, g) NCM@cPAN powders; (h, i) TEM images of NCM@cPAN; (j) EDS mappings of C, N, O, Mn, Co and Ni elements of the region in (f)

4. Cycling performance of solid-state NCM@cPAN+IL/PEO/Li batteriesTypical charge-discharge curves and the corresponding specific capacities with cutoff voltages of (a, d) 4.20 V, (b, e) 4.25 V, and (c, f) 4.30 V

5. (a) Charge-discharge curves, and (b) corresponding specific capacities for solid-state NCM@cPAN+IL/PEO/Li batteries at various current densities; (c) Typical charge-discharge curves and (d) corresponding specific capacities and Coulombic efficiency for solid-state NCM@cPAN+IL/PEO/Li batteries with high cathode loading of ~6.2 mg·cm^-2

6. (a, c) F1s and (b, d) N1s XPS spectra of PP13-TFSI (a, b) before and (c, d) after cycling; (e) Schematic diagram of TFSI⁻ decomposition during cycling

7. (a) FT-IR spectra of PEO electrolyte before and after cycling; SEM images of NCM@cPAN cathodes (b) before and (c) after cycling; (d) Ni2p XPS spectra of NCM@cPAN cathode before and after cycling

S1. (a) Nyquist plots of PEO-based electrolyte at different temperatures; (b) Arrhenius plot of PEO-based electrolyte

S2. LSV curve of PEO-based electrolyte

S3. Charge-discharge curve of NCM/PEO/Li batteries without IdiL at 50 ℃

S4. Rate performance of solid NCM@cPAN+IL/PEO/Li batteries at various current densities(a, c) Typical charge-discharge curves and (b, d) corresponding specific capacities with the cutoff voltages of (a, b) 4.25 V, and (c, d) 4.30 V

S5. Charge-discharge curve of NCM@cPAN/PEO/Li batteries without IL at 50 ℃

S6. Charge-discharge curve of NCM/PEO/Li batteries with IL at 50 ℃

S7. XRD patterns of PEO electrolytes before and after cycling