Method for recycling battery electrodes
Provided is a method for recycling a battery electrode by immersing the electrode into a delamination solution and subsequently precipitating a polymeric binder with the addition of a precipitation agent; wherein the electrode comprises a current collector and an electrode layer material coated on one side or both sides of the current collector; wherein the electrode layer material comprises a polymeric binder; and wherein the polymeric binder comprises a copolymer comprising a structural unit derived from an acid group-containing monomer and a structural unit derived from a hydrogen bond-forming group-containing monomer (ii). The method disclosed herein circumvents complex separation process, corrosion of current collector and contamination of polymeric binder, enables excellent materials recovery and allows the recycling of battery electrode to be achieved in a highly efficient manner.
1 . A method for recycling a battery electrode, comprising the steps of:
a) immersing an electrode, comprising a current collector and an electrode layer material coated on one side or both sides of the current collector, into a delamination solution to form a heterogeneous mixture, wherein the electrode layer material comprises a polymeric binder and an electrode active material;
b) screening the heterogeneous mixture to separate the current collector and the electrode layer material from the delamination solution;
c) adding the electrode layer material and a precipitation agent into an aqueous solvent to form a first suspension, and then precipitating the polymeric binder;
wherein the delamination solution comprises a delamination agent and an aqueous solvent, wherein the delamination agent is a weak acid;
wherein the polymeric binder comprises a copolymer comprising a structural unit derived from an acid group-containing monomer and a structural unit derived from a hydrogen bond-forming group-containing monomer (ii); wherein the hydrogen bond-forming group-containing monomer (ii) is selected from the group consisting of a nitrile group-containing monomer, an ester group-containing monomer, an epoxy group-containing monomer, a fluorine group-containing monomer and combinations thereof; and
wherein the precipitation agent is a strong acid, a weak acid or a combination thereof.
2 . The method of claim 1 , wherein the copolymer further comprises a structural unit derived from a hydrogen bond-forming group-containing monomer (i); wherein the hydrogen bond-forming group-containing monomer (i) is selected from the group consisting of an amide group-containing monomer, a hydroxyl group-containing monomer and combinations thereof.
3 . The method of claim 2 , wherein the amide group-containing monomer is selected from the group consisting of acrylamide, methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, N-n-propyl methacrylamide, N-isopropyl methacrylamide, isopropyl acrylamide, N-n-butyl methacrylamide, N-isobutyl methacrylamide, N,N-dimethyl acrylamide, N,N-dimethyl methacrylamide, N,N-diethyl acrylamide, N,N-diethyl methacrylamide, N-methylol methacrylamide, N-(methoxymethyl) methacrylamide, N-(ethoxymethyl) methacrylamide, N-(propoxymethyl) methacrylamide, N-(butoxymethyl) methacrylamide, N,N-dimethylaminopropyl methacrylamide, N,N-dimethylaminoethyl methacrylamide, N,N-dimethylol methacrylamide, diacetone methacrylamide, diacetone acrylamide, methacryloyl morpholine, N-hydroxyl methacrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, N,N′-methylene-bis-acrylamide (MBA), N-hydroxymethyl acrylamide and combinations thereof; and wherein the proportion of structural unit derived from an amide group-containing monomer is from about 0% to about 85% by mole, based on the total number of moles of monomeric units in the copolymer in the polymeric binder.
4 . The method of claim 1 , wherein the molar ratio of the structural unit derived from an acid group-containing monomer to the structural unit derived from a hydrogen bond-forming group-containing monomer (ii) in the copolymer is from about 0.1 to about 5; and wherein the proportion of the structural unit derived from a hydrogen bond-forming group-containing monomer (ii) is from about 5% to about 85% by mole, based on the total number of moles of monomeric units in the copolymer in the polymeric binder.
5 . The method of claim 1 , wherein the current collector is in the form of a foil, sheet, film or a combination thereof; and wherein the current collector is selected from the group consisting of stainless steel, titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, silicon, tin, vanadium, zinc, cadmium, or alloys thereof, electrically-conductive resin and combinations thereof.
6 . The method of claim 1 , wherein the acid group-containing monomer is selected from the group consisting of a carboxylic acid group-containing monomer, a sulfonic acid group-containing monomer, a phosphonic acid group-containing monomer and combinations thereof; and wherein the pK a of the acid group-containing monomer is at least 0.1 pH unit above the pK a of the precipitation agent.
7 . The method of claim 6 , wherein the carboxylic acid group-containing monomer is selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, 2-butyl crotonic acid, cinnamic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, 4,4-dimethyl itaconic acid, 2-ethylacrylic acid, isocrotonic acid, cis-2-pentenoic acid, trans-2-pentenoic acid, angelic acid, tiglic acid, 3,3-dimethyl acrylic acid, 3-propyl acrylic acid, trans-2-methyl-3-ethyl acrylic acid, cis-2-methyl-3-ethyl acrylic acid, 3-isopropyl acrylic acid, trans-3-methyl-3-ethyl acrylic acid, cis-3-methyl-3-ethyl acrylic acid, 2-isopropyl acrylic acid, trimethyl acrylic acid, 2-methyl-3,3-diethyl acrylic acid, 3-butyl acrylic acid, 2-butyl acrylic acid, 2-pentyl acrylic acid, 2-methyl-2-hexenoic acid, trans-3-methyl-2-hexenoic acid, 3-methyl-3-propyl acrylic acid, 2-ethyl-3-propyl acrylic acid, 2,3-diethyl acrylic acid, 3,3-diethyl acrylic acid, 3-methyl-3-hexyl acrylic acid, 3-methyl-3-tert-butyl acrylic acid, 2-methyl-3-pentyl acrylic acid, 3-methyl-3-pentyl acrylic acid, 4-methyl-2-hexenoic acid, 4-ethyl-2-hexenoic acid, 3-methyl-2-ethyl-2-hexenoic acid, 3-tert-butyl acrylic acid, 2,3-dimethyl-3-ethyl acrylic acid, 3,3-dimethyl-2-ethyl acrylic acid, 3-methyl-3-isopropyl acrylic acid, 2-methyl-3-isopropyl acrylic acid, trans-2-octenoic acid, cis-2-octenoic acid, trans-2-decenoic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, bromo maleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, difluoro maleic acid, nonyl hydrogen maleate, decyl hydrogen maleate, dodecyl hydrogen maleate, octadecyl hydrogen maleate, fluoroalkyl hydrogen maleate, maleic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, acrylic anhydride, methacrylic anhydride, methacrolein, methacryloyl chloride, methacryloyl fluoride, methacryloyl bromide and combinations thereof.
8 . The method of claim 6 , wherein the sulfonic acid group-containing monomer is selected from the group consisting of vinylsulfonic acid, methylvinylsulfonic acid, allylvinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-sulfoethyl methacrylic acid, 2-methylprop-2-ene-1-sulfonic acid, 2-acrylamido-2-methyl-1-propane sulfonic acid, 3-allyloxy-2-hydroxy-1-propane sulfonic acid and combinations thereof.
9 . The method of claim 6 , wherein the phosphonic acid group-containing monomer is selected from the group consisting of vinyl phosphonic acid, allyl phosphonic acid, vinyl benzyl phosphonic acid, acrylamide alkyl phosphonic acid, methacrylamide alkyl phosphonic acid, acrylamide alkyl diphosphonic acid, acryloylphosphonic acid, 2-methacryloyloxyethyl phosphonic acid, bis(2-methacryloyloxyethyl) phosphonic acid, ethylene 2-methacryloyloxyethyl phosphonic acid, ethyl-methacryloyloxyethyl phosphonic acid and combinations thereof.
10 . The method of claim 1 , wherein the proportion of structural unit derived from an acid group-containing monomer is from about 5% to about 85% by mole, based on the total number moles of monomeric units in the copolymer in the polymeric binder.
11 . The method of claim 1 , wherein the nitrile group-containing monomer is selected from the group consisting of acrylonitrile, α-halogenoacrylonitrile, α-alkylacrylonitrile, α-chloroacrylonitrile, α-bromoacrylonitrile, α-fluoroacrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-n-hexylacrylonitrile, α-methoxyacrylonitrile, 3-methoxyacrylonitrile, 3-ethoxyacrylonitrile, α-acetoxyacrylonitrile, α-phenylacrylonitrile, α-tolylacrylonitrile, α-(methoxyphenyl) acrylonitrile, α-(chlorophenyl) acrylonitrile, α-(cyanophenyl) acrylonitrile, vinylidene cyanide and combinations thereof; and wherein the proportion of structural unit derived from a nitrile group-containing monomer is from about 5% to about 85% by mole, based on the total number moles of monomeric units in the copolymer in the polymeric binder.
12 . The method of claim 1 , wherein the weak acid of each of the delamination agent and the precipitation agent is independently selected from the group consisting of formic acid, acetic acid, glycolic acid, glyoxylic acid, oxalic acid, propionic acid, acrylic acid, propiolic acid, lactic acid, 3-hydroxypropionic acid, glyceric acid, pyruvic acid, 3-oxopropionic acid, 2,3-dioxopropionic acid, malonic acid, tartronic acid, dihydroxymalonic acid, mesoxalic acid, glycidic acid, butyric acid, isobutyric acid, crotonic acid, isocrotonic acid, methacrylic acid, vinylacetic acid, tetrolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-oxobutanoic acid, acetoacetic acid, 4-oxobutanoic acid, butanedioic acid, methylmalonic acid, fumaric acid, maleic acid, 2-hydroxybutanedioic acid, tartaric acid, oxaloacetic acid, dioxosuccinic acid, valeric acid, isovaleric acid, 2-methylbutyric acid, pivalic acid, 3-hydroxyvaleric acid, 4-hydroxypentanoic acid, 3-hydroxyisovaleric acid, glutaric acid, 2-oxoglutaric acid, 3-oxoglutaric acid, 2-furoic acid, tetrahydrofuroic acid, hexanoic acid, hexanedioic acid, citric acid, aconitic acid, isocitric acid, sorbic acid, pimelic acid, benzoic acid, salicylic acid, 4-carboxybenzoic acid, trimesic acid, mellitic acid, malic acid, dithionous acid, phosphoric acid, nitrous acid, orthosilicic acid and combinations thereof; and wherein the pK a of the weak acid of each of the delamination agent and the precipitation agent is independently from about 2 to about 7.
13 . The method of claim 1 , wherein the aqueous solvent used in each of step c) and the delamination solution is independently water or a solution consisting of water as a major component and a volatile solvent as a minor component, such that the proportion of water in the aqueous solvent is from about 51% to about 100% by weight.
14 . The method of claim 13 , wherein the minor component is selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, tert-butanol, n-butanol, acetone, dimethyl ketone, methyl ethyl ketone, ethyl acetate, isopropyl acetate, propyl acetate, butyl acetate and combinations thereof.
15 . The method of claim 1 , wherein the weight ratio of the electrode to the delamination solution is from about 0.01% to about 15%; wherein the pH of the first suspension is from about 0.2 to about 4.5; and wherein the pH of the first suspension is at least 0.2 pH unit below the pK a of the acid group-containing monomer.
16 . The method of claim 1 , wherein the strong acid is selected from the group consisting of nitric acid, sulphuric acid, hydrochloric acid, perchloric acid, hydrobromic acid, hydroiodic acid, chloric acid, bromic acid, iodic acid, dithionic acid, dithionous acid, sulfamic acid, trithionic acid, tetrathionic acid, methane sulphonic acid, p-toluenesulfonic acid, benzene sulfonic acid, trichloroacetic acid, trifluoroacetic acid, oxalic acid, propiolic acid, mesoxalic acid, mellitic acid and combinations thereof; and wherein the pK a of the strong acid is from about-10 to about 2.
17 . The method of claim 1 , wherein the concentration of the delamination agent in the delamination solution is from about 0.01% to about 3.5% by weight, based on the total weight of the delamination solution.
18 . The method of claim 1 , wherein the electrode layer material and the precipitation agent are added simultaneously to form the first suspension.