Fig. 1

(a) Annual sales volume of domestic new energy vehicles and domestic electrolyte shipments from 2016 to 2030. Note: the data are from intelligent research information; (b) Statistics of articles and related patents related to electrolyte recovery of lithium ion batteries from 2011 to 2022. (data source: CNKI)"

Fig. 2

(a) Composition of lithium ion battery and electrolyte; (b) Composition of electrolyte; (c) Structural formula of the most commonly used electrolyte solvent and solute[13]"

Fig. 3

Mechanism of electrolyte failure: (a) the battery short circuit causes the electrolyte to dry up; (b) the electrolyte solvent loss is caused by the catalytic reaction of Mn2+ to the electrolyte[20]; (c) the decomposition of LiPF6"

Fig. 4

Reduction processes of DMC and EC: (a) one-electron nucleophilic attack reaction of DMC; (b) two-electron nucleophilic attack reaction of DMC; (c) one-electron nucleophilic attack reaction of EC; and (d) two-electron nucleophilic attack reaction of EC; (e) formation pathways of hydrocarbons and fluorohydrocarbons[21]"

Fig. 5

cases of recycling lithium ion battery electrolyte by domestic and foreign enterprises: (a) GEM Co., Ltd.[23]; (b) Umicore Group[24]; (c) AEA Technology; (d) OnTo; (e) Recupyl[25]"

Fig. 6

mechanism of electrolyte recovery method: (a) Freezing method; (b) Mechanical centrifugation; (c) Organic solvent extraction; (d), (e) Supercritical carbon dioxide extraction[26]; (f) Recovery method of lithiums"

Fig. 7

Enrichment method of electrolyte: (a) Technical route of freezing method; (b) Recovery of electrolyte by mechanical centrifugation[29]; (c) Technical route of electrolyte recovery by solvent method[33] (d) Schematic diagram of electrolyte recovery by supercritical carbon dioxide method[34]"

Table 1

Comparison of advantages and disadvantages of electrolyte recovery methods"

Fig. 8

Crystal structure and decomposition reaction diagram of lithium hexafluorophosphate"

Fig. 9

Four requirements for electrolyte recovery"