Recycling and upcycling of nickel-based lithium cathode materials
A method for processing spent nickel-based cathode material useful in lithium-based batteries, the method comprising: (i) producing an initial mixture containing the spent nickel-based cathode material and a molten salt system comprising cations and anions, wherein the cations comprise lithium cations; (ii) heating the initial mixture to a temperature of 700° C. to 900° C. for at least 1 hour to produce a relithiated cathode material; and (iii) washing the relithiated cathode material to remove any residual salt. In a further method, the cations comprise nickel and lithium cations and the anions comprise chloride or bromide anion in combination with at least one of nitrate, sulfate, and carbonate anions in further combination with hydroxide anion, wherein the method results in upcycling of the nickel-based cathode material to produce a version of said relithiated cathode material having a greater nickel content.
1 . A method for processing spent nickel-based cathode material useful in lithium-based batteries, the method comprising: (i) producing an initial mixture containing the spent nickel-based cathode material and a molten salt system comprising cations and anions, wherein the cations comprise lithium and nickel cations, by mixing the spent nickel-based cathode material and a mixture of salt powders comprising lithium and nickel salt powders, to produce a precursor powder mixture, followed by heating the precursor powder mixture at a temperature of 250° C. to 400° C. for at least 1 hour to melt the mixture of salt powders to form the molten salt system in the presence of the spent nickel-based cathode material to produce the initial mixture; (ii) heating the initial mixture to a temperature of 700° C. to 900° C. for at least 1 hour to produce a relithiated cathode material having a greater nickel content than the spent nickel-based cathode material; and (iii) washing the relithiated cathode material to remove any residual salt.
2 . The method of claim 1 , wherein the spent nickel-based cathode material is spent Ni—Co—Al (NCA) cathode material.
3 . The method of claim 1 , wherein the anions comprise chloride or bromide anion in combination with nitrate anions in further combination with hydroxide anions.
4 . The method of claim 1 , wherein, in step (ii), the initial mixture is heated to a temperature of 750° C. to 900° C. for at least 1 hour.
5 . The method of claim 1 , wherein, in step (ii), the initial mixture is heated to a temperature of 775° C. to 900° C. for at least 1 hour.
6 . The method of claim 1 , wherein, in step (ii), the initial mixture is heated to a temperature of 750° C. to 900° C. for at least 3 hours.
7 . The method of claim 1 , wherein, in step (ii), the initial mixture is heated to a temperature of 775° C. to 900° C. for at least 3 hours.
8 . The method of claim 1 , wherein step (i) the spent nickel-based cathode material is in powder form.
9 . The method of claim 1 , wherein step (iii) comprises washing the relithiated cathode material with water to remove any residual salt.
10 . The method of claim 1 , wherein, in step (ii), the initial mixture is raised to said temperature of 700° C. to 900° C. gradually at a temperature ramp rate of 1° C./min to 10° C./min.
11 . The method of claim 1 , wherein the relithiated cathode material is incorporated into a cathode of a lithium-based battery.
12 . The method of claim 1 , wherein the method converts spent NCM 111 cathode material to NCM 622 or NCM 811 cathode material.
13 . The method of claim 1 , wherein the spent nickel-based cathode material is in powder form.
14 . The method of claim 13 , wherein the powder has a particle size of up to 100 microns.
15 . The method of claim 1 , wherein the cations comprise nickel and lithium cations and the anions comprise chloride or bromide anion in combination with at least one of nitrate, sulfate, and carbonate anions in further combination with hydroxide anion, wherein the method results in upcycling of the nickel-based cathode material to produce a version of said relithiated cathode material having a greater nickel content.
16 . The method of claim 15 , wherein the cations comprise nickel, lithium, and at least one other alkali metal cation selected from sodium, potassium, and cesium cations.
17 . The method of claim 1 , further comprising: (iv) drying the relithiated cathode material after washing.
18 . The method of claim 17 , further comprising: (v) heating the relithiated cathode material in an oxygen-containing atmosphere to a temperature of 500° C. to 700° C. for at least 1 hour after washing and drying the relithiated cathode material.
19 . The method of claim 1 , wherein the spent nickel-based cathode material is spent Ni—Mn—Co (NMC) cathode material.
20 . The method of claim 19 , wherein the spent Ni—Mn—Co (NMC) cathode material is spent NMC-111 cathode material.
21 . The method of claim 19 , wherein the spent Ni—Mn—Co (NMC) cathode material is spent NMC-622 cathode material.
22 . The method of claim 19 , wherein the spent Ni—Mn—Co (NMC) cathode material is spent NMC-811 cathode material.