Fig. 1

Crystal structure of α-NaFeO2[8]"

Fig. 2

(a) Schematic diagram of Ni2+/Li+ cation mixing[15]; (b) Capacity fading scheme of Ni-rich Li[Ni x Co y Mn1-x-y ]O2 cathodes[16]; (c) Residual alkali on material surface[17]; (d) Schematic diagram of by-products on material surface[18]"

Fig. 3

(a) Schematic diagram of the proposed doping strategy of Nb-doped; (b) HRTEM images of N0 and N2[31]；(c) calculated density of states for 1.66% Mo-NCM811; (d) Schematic structure of NCM811 undoped and Mo-doped materials[32]; (e) Schematic structure of NCMMg0.03[33]"

Fig. 4

(a) Schematic illustration of the preparation of NCM811@PANI-PVP;(b) HRTEM images of NCM811@PANI-PVP[38]; (c) Schematic illustration of the preparation procedure[39]; (d) Coating-plus-infusion’ microstructure for Co x B-infused NCM; (e) EELS line scan at a secondary-particle surface in cycled pristine NCM and Co x B-NCM[40]"

Fig. 5

(a) Zr 3d peaks of SC-NCM and 5-ZrO2-NCM annealed at different temperatures[44]; (b) Effect of annealing temperature on material properties[45]; (c) Schematic illustration of the effect of ZrB2 doping on the NCM811 cathode’s mechanical stability during cycling[46]"

Fig. 6

(a) Summary of the three main approaches to single-crystal synthesis[50]; (b) TEM image of the S-NCM90 cathode particle charged to 4.3 V at 0.5 C and the c-axis lattice parameters at locations along the dashed yellow line[51]; (c) Schematic illustration of crack evolution and the internal morphological difference for N-NCM and SC-NCM cathodes during prolong cycling; (d) Cycling performances of N-NCM and SC-NCM electrodes in pouch-type full-cells [52]"

Fig. 7

(a) Synthesis illustrative diagram of structure-gradient NCM811[65]; (b) SEM of a typicle particle cross-section; (c) EPMA line scan data of Li (Ni0.64Co0.18Mn0.18)O2[66]; (d) Spherical gradient nickel-rich material[67]"

Fig. 8

Comparisons of different improving methods for NCM materials"