Extended Data Fig. 1: Post-cycling morphological, structural and chemical characteristics of oxide surface and CEIs.

a, b, HRTEM near the surface of cycled P-LCO (a) and La-LCO (b). Circled in (a) are Moire effects produced by lattice distortion. c, d, Depth-resolved EELS profiles near the surface of cycled P-LCO (c) and La-LCO (d). e, f, Calculated Co L₃/L₂ area ratio (e) and O/Co ratio (f) of cycled P-LCO and La-LCO from (c, d). g, h, HRTEM near the surfaces of cycled P-LCO (g) and La-LCO (h), showing the CEI layer enclosed by dash lines. Scale bars: 5 nm (a, b, g, h). i–l, XPS of C 1s (i, k) and F 1s (j, l) for cycled P-LCO (i, j) and La-LCO (k, l). Details for XPS analysis are listed in Supplementary Table 5 and 6. Characterizations in (a–l) were conducted on samples after 100 cycles at 1 C and 3.0–4.6 V (vs. Li⁺/Li) in half cells. m, Dissolved Co in the electrolytes after 100 and 200 cycles under 1 C within 3.0–4.6 V (vs. Li⁺/Li) in half cells. n, o, XPS of Co 2p at the surface of the cycled graphite anodes in pouch cells using La-LCO (n) and P-LCO (o) cathodes after 200 cycles under 200 mA at full-cell voltages 3.0–4.5 V.