Fig. 5: Mechanistic studies.

a HPPC results of GP-NCM and P-NCM full cells measured at a series of SoCs. These cells were cycled at 1 C-1 C rate. The HPPC tests were carried out after the first and the 50^th cycles. b, c are EIS spectra of GP-NCM and P-NCM half cells measured after the 25^th, 50^th, 75^th, and 100^th cycles, respectively. The equivalent circuit model is shown in the inset. d, e are STEM-HAADF images of primary particles’ surface after cycling and the associated fast-Fourier-transform diffractograms. These samples were prepared by FIB and cut from the cracked region of the NCM secondary particles (see Supplementary Fig. 15). f, g show the representative cross-sectional SEM images of broken, mildly damaged, and intact NCM secondary particles for cycled GP-NCM and P-NCM, respectively. h Counts of different types of particles after 30 and 100 cycles at 1 C. The corresponding percentages are shown in panels (i and j). 2042 secondary particles were analyzed. Their cross-sectional SEM images are included in Supplementary Figs. 16–19.