Fig. 1

Schematic diagram of RLCs in this paper"

Fig. 2

Surface reaction diagram of high-nickel ternary cathode material in air[5]"

Fig. 3

(a), (b) Schematic diagram of the atomic structure and delithiated NCM of high-nickel ternary cathode materials (NCM) moving from the interior to the surface 3b site under the adsorption of gas molecules. The black dotted line indicates the migrating lithium ions, and the black arrow points to the surface site to which the subsurface lithium migrates. (c) Li migration energy diagram under H2O, O2, CO2 and N2 adsorption [15]"

Fig. 4

(a) Titration results of lithium residue content of cathode materials[31]; (b) Titration curve of 0.025 mol/L lithium hydroxide analyte prepared with water (black) and methanol (red) as solvents[36]"

Fig. 5

XPS spectra of C 1s [(a), (b)] and O 1s [(c), (d)] on the surface after 200 cycles of NCA and NCA-LTO 3 at 1 C, 3—4.3 V[42]; [(e), (f)] Ratio of sodium residue and lattice oxygen to etching time on NCMT and NMP@NCMT-2 surfaces[43]"

Fig. 6

(a) Raman spectra of LLZTO and LPF-LLZTO; (b) FTIR spectra of LLZTO, Air-LLZTO and LPF-LLZTO[44]; (c), (d) FTIR spectra of raw SC-NCM and 0.5-NCM@TiO2[45]"

Fig. 7

(a) normalized depth profile of representative species in F-Sb-NCMA93[47]; (b) 11B NMR analysis of the supernatant after the completion of the chemical reaction between TPB, LiOH and Li2CO3[48]; TG-DSC curve of lithium tetraborate formed by the reaction of (c), (d) Li2CO3 with boric acid and LiOH with boric acid[49]"

Fig. 8

Flow chart of deionized water washing and alkali removal[28]"

Fig. 9

(a)—(c) Comparison of drying time, particle size and electrochemical performance of cathode materials after drying by the two methods[52]; (d) Newly prepared sample F, (e) sample EF2 washed twice with ethanol, (f) sample ES2 first placed in air for 1 d and then washed twice with ethanol stored in air for 3 months before and after the first and thirtieth discharge curves[55]"

Fig. 10

(a) Schematic diagram of TiO2 deposition on the NCM surface[63]; (b) Schematic illustration of the PrF3 coating procedure; (c) A schematic image of the enhanced structural stability by PrF3 coating [68]"

Fig. 11

Schematic diagram of the possible protection mechanism of DMS additives in high-nickel layered cathode materials[72]"

Fig. 12

Schematic diagram of the surface chemical reaction between the original sample and the Li3PO4-modified NCM811 cathode material (LP) (a); Cycling performance in the (b) 1 C and 8 C and (c) 1 C, 55 ℃ and 3.0—4.4 V voltage ranges; (d) Rate performance of the original sample and (e) the modified sample[81]"

Fig. 13

(a) Schematic diagram of the synthesis process of SiO2-Li2SiO3 coated NCM811; Cycling performance of S0—S4 samples at (b), (c) 1 C and 25 ℃; Rate performance at (d), (e) different current densities, S0—S4 indicates unmodified, different LiOH content (1.07%, 1.09%, 1.11% and 1.13%) and EPS-modified NCM811 cathode material[2]"

Fig. 14

(a) Schematic diagram of Li2B4O7 and B3+ modified LiNi0.925Co0.03Mn0.045O2 cathode materials; electrochemical performance of the original and modified samples in the range of 2.8—4.3 V; (b) cycle performance at 55 ℃, (c)—(e) rate performance at 25 ℃[49]"

Fig. 15

(a) Schematic diagram of the NCA-LTO3 reaction process[42]; (b) schematic diagram of the synthetic route of InSn-NMA85[82]; (c) Schematic diagram of the change of RLCs after activation of LiNi0.95Mn0.05O2 (NM95-H) and (d) LiNi0.95Mn0.05O2 (NM95-L) cathode with low RLCs content at 2.7—4.3 V and 2.7—4.5 V with high surface RLCs content[31]"

Fig. 16

Description of the separation process and results (a) Schematic diagram of the separation process and possible separation mechanisms, optical photograph of (b) degraded electrode sheet and (c) aluminum foil with a size of 2 cm×2 cm after separation; (d) Mapping results of SEM images and (e) separated aluminum foil; Scanning electron microscopy images of electrodes before (f) and (g) before water treatment; (h) Flowering strength of each electrode before and after water treatment[84]"

Fig. 17

(a) Schematic diagram of the NMP@NCMT-2||HC full battery; (b) GCD patterns of NMP@NCMT-2 and hard carbon (HC) with a capacity ratio of 1.05∶1 for the electrodes; (c) GCD plot of a whole cell at different current densities; (d) Cycling performance of the full battery at 1.2 C; (e) Comparison of electrochemical performance of NMP@NCMT-2//HC with other sodium-ion battery cathode materials for whole batteries; Specific energy density is based on the total mass load (the size of the shape is proportional to the cyclic stability)[43]"