Method for dissolving a positive electrode material

Abstract

A method for dissolving a positive electrode material of a battery including a step during which the positive electrode material, comprising lithium and optionally cobalt and/or nickel, is submerged in an acid solution having a pH between 0 and 4, the acid solution containing either manganese ions or hydrogen peroxide, by means of which the lithium and optionally the cobalt and/or nickel is dissolved, and the manganese ions are selectively precipitated in the form of manganese oxyhydroxide.

Claims

1. A method for dissolving a positive electrode material of a battery comprising a step during which the positive electrode material, including lithium, manganese and possibly cobalt and/or nickel, is immersed in an acid solution at a pH comprised between 0 and 4, wherein the acid solution contains hydrogen peroxide, whereby, on the one hand, the lithium and possibly the cobalt and/or the nickel are put into solution and, on the other hand, the manganese is dissolved, which selectively precipitates in the form of a manganese oxyhydroxide.

2. The method according to claim 1, wherein the manganese of the positive electrode material is entirely recovered in the form of manganese oxohydroxide.

3. The method according to claim 1, wherein the duration of the leaching step is between 1 h and 24 h.

4. The method according to claim 1, wherein the volume concentration of hydrogen peroxide is between 1% and 12%, and preferably between 1% and 6%.

5. The method according to claim 4, wherein the volume concentration of hydrogen peroxide is between 1% and 4%.

6. The method according to claim 5, wherein the volume concentration of hydrogen peroxide is between 2% and 3%.

7. The method according to claim 1, wherein the pH is between 1 and 2.5.

8. The method according claim 1, wherein the solid/liquid ratio is between 5% and 40%, and advantageously between 5% and 20%.

9. The method according to claim 1, wherein the ratio between the volume concentration of hydrogen peroxide and the solid/liquid ratio is between 0.1 and 0.4 and preferably between 0.2 and 0.3.

10. The method according to claim 1, wherein the positive electrode is an NMC electrode.

11. The method according to claim 1, wherein the temperature of the solution is between 70? C. and 100? C., preferably between 80? C. and 95? C.

12. The method according to claim 1, wherein the positive electrode material is in a particulate form.

13. The method according to claim 1, wherein the solid/liquid ratio is between 5% and 40% and the volume concentration of hydrogen peroxide is between 1% and 12%.

14. The method according to claim 13, wherein the solid/liquid ratio is comprised between 5% and 20% and the volume concentration of hydrogen peroxide is between 1% and 6%.

15. The method according to claim 1, wherein the solid/liquid ratio is between 5% and 10%, the pH is comprised between 1 and 2.5 and the volume concentration of hydrogen peroxide is between 1% and 3%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The present invention will be better understood upon reading the description of embodiments given for purely indicative and non-limiting purposes with reference to the appended drawings wherein:

[0067] FIG. 1 is a graph showing the dissolution yield of an NMC powder (1/1/1) in a sulphuric acid solution at pH=1 with stoichiometric manganese sulphate, at a temperature of 72? C., with an S/L ratio of 20%, with stirring at 400 rpm, as a function of time, according to a first variant of the method of the invention,

[0068] FIG. 2 is a graph showing the concentration of ions in the solution as a function of time during the treatment of an NMC powder (6/2/2) in a sulphuric acid solution at pH=2.5 with manganese sulphate at a temperature of 100? C. with an S/L ratio of 20%, with stirring at 400 rpm, according to a second variant of the method of the invention.

[0069] FIG. 3 is a graph showing the dissolution yield of the ions, Li, Ni, Mn, Co as a function of the volume concentration of hydrogen peroxide at different concentrations, after 24 h of treatment of an NMC powder (1/1/1), in a sulphuric acid solution at pH=1 at a temperature of 80? C. with an S/L ratio of 10%, under stirring at 400 rpm, according to another variant of the method of the invention.

[0070] FIG. 4 is a graph showing the dissolution yield of the ions, Li, Ni, Mn, Co as a function of the volume concentration of hydrogen peroxide at different concentrations, after 24 h of treatment of an NMC powder (6/2/2), in a sulphuric acid solution at pH=1 at a temperature of 80? C. with an S/L ratio of 10%, under stirring at 400 rpm, according to another variant of the method of the invention.

[0071] FIG. 5 is a graph showing the dissolution yield of the ions, Li, Ni, Mn, Co as a function of the volume concentration of hydrogen peroxide at different concentrations, after 24 h of treatment of an NMC powder (8/1/1), in a sulphuric acid solution at pH=1 at a temperature of 80? C. with an S/L ratio of 10%, under stirring at 400 rpm, according to another variant of the method of the invention.

DETAILED DISCLOSURE OF PARTICULAR EMBODIMENTS

[0072] The invention particularly finds applications in the field of recycling and/or recovery of batteries/accumulators/cells of the Li-ion type, and in particular of their electrodes.

[0073] Next, reference will be made to a battery, but it could consist of a cell or an accumulator.

[0074] Next, by battery waste, it should be understood the battery or a portion of the battery that has been recovered after safeguarding and dismantling the battery.

[0075] The battery waste comprises lithium and possibly cobalt and/or nickel.

[0076] According to a particularly advantageous embodiment, the waste battery further comprises manganese.

[0077] The battery waste may also comprise aluminium.

[0078] In particular, the battery waste is a positive electrode whose active material may be LiCoO.sub.2 (lithium cobalt oxide (LCO)), LiMnO.sub.2, LiNiO.sub.2, LiNiCoAlO.sub.2 (nickel-cobalt-aluminium (NCA)) or LiNi.sub.xMn.sub.yCo.sub.zO.sub.2. (NMC (nickel-manganese-cobalt)).

[0079] Preferably, an NMC or LiMnO.sub.2 electrode will be selected. The NMC electrode may have different ratios of nickel, cobalt and manganese. For example, the ratio may be 1/1/1, 5/3/2, 6/2/2, 8/1/1 or 9/0.5/0.5.

[0080] The battery waste may further contain other species. The other species may be metals, alkali metals and/or rare-earth elements. As an illustrative and non-limiting example, mention may be made of the following elements: Fe, Zn, Al, Mg, Cu, Ca, Pb, Cd, La, Ti, V, Nd and Ce.

[0081] Advantageously, the battery waste is ground before the dissolution step, whereby a ground matter is formed. For example, the particles of the ground matter have a largest dimension smaller than 1 cm.

[0082] Alternatively, the method may also be carried out directly on unground battery waste.

[0083] It is also possible to carry out one or more material concentration step(s) (such as sieving, eddy current, etc.).

[0084] The method for dissolving a battery positive electrode material according to the invention includes the following steps: [0085] providing a positive electrode material including lithium and, possibly, cobalt and/or nickel and/or manganese, [0086] carrying out a leaching step by immersing the positive electrode material in an acid solution at a pH comprised between 0 and 4, containing either manganese ions or hydrogen peroxide or a mixture of manganese ions and hydrogen peroxide, whereby the lithium and possibly the cobalt and/or the nickel are put into solution and, where appropriate, the manganese ions are selectively precipitated in the form of manganese oxyhydroxide.

[0087] Advantageously, with such a method, different electrode materials can be treated simultaneously as a mixture.

[0088] The method according to the invention also allows treating a concentrated powder of positive electrode material which has been obtained, for example, after a step of separating the active material from the current collector.

[0089] The selective dissolution phase ensures complete dissolution of valuable elements (lithium, nickel and/or cobalt) and, where appropriate, the separation of manganese in one single step.

[0090] The positive electrode material (preferably NMC, LiMnO.sub.2), preferably in the form of powder, is introduced in a solid/liquid ratio of 5% to 40%, and advantageously between 15% and 30% (g/mL).

[0091] Preferably, the solution is an aqueous solution. It could also consist of an organic solution.

[0092] Advantageously, the acid is selected from among mineral acids, for example from hydrochloric acid, phosphoric acid, nitric acid, sulphuric acid or a mixture thereof. Preferably, sulphuric acid will be selected since it is the least corrosive for the materials used in the method, it has fewer dangers during use thereof and it is easily available, at a relatively low cost.

[0093] The pH is comprised between 0 and 4, preferably between 1 and 2.5. For example, a pH of 2 will be selected.

[0094] Advantageously, a servo-control device is used to maintain a constant pH (within a 10% margin) throughout the treatment.

[0095] According to a first variant, the leaching solution contains a manganese salt. Advantageously, the manganese salt is added in a stoichiometric amount or in excess to ensure a complete dissolution.

[0096] Advantageously, the manganese salt may be a salt of manganese chloride, manganese nitrate, manganese sulphate. Advantageously, these salts have a good solubility in water. Preferably, a manganese sulphate salt will be selected, to avoid the presence of nitrate or of chloride in solution.

[0097] It could also consist of manganese hydroxide.

[0098] According to a second variant, the leaching solution contains hydrogen peroxide. Preferably, the volume concentration of hydrogen peroxide is comprised between 0.1% and 16%, and preferably between 1% and 12%, for example between 1% and 10%.

[0099] According to one variant, the leaching solution further contains a manganese salt. Advantageously, the manganese salt may be a salt of manganese chloride, manganese nitrate, manganese sulphate. Advantageously, these salts have a good solubility in water. Preferably, a manganese sulphate salt will be selected, to avoid the presence of nitrate or of chloride in solution. It could also consist of manganese hydroxide.

[0100] Advantageously, the volume concentration of hydrogen peroxide will be selected according to the S/L ratio. Preferably, the ratio between the volume concentration of hydrogen peroxide and the S/L ratio is comprised between 0.1 and 0.4, and even more preferably between 0.2 and 0.3.

[0101] For illustration, the following table reports different volume concentrations of hydrogen peroxide associated with different S/L ratios that can be used to implement the method:

TABLE-US-00001 S/L Volume concentration of Preferred volume concentration of ratio (%) hydrogen peroxide (%) hydrogen peroxide (%) 1 0.1-0.4 0.2-0.3 5 0.5-2.sup. .sup.1-1.5 10 1-4 2-3 20 2-8 4-6 25 2.5-10 .sup.5-7.5 40 4-16 8-12

[0102] The duration of the leaching step may be comprised between 1 h and 24 h. The duration of the leaching step can be adapted according to the temperature of the solution. The temperature of the solution may be comprised between 70? C. and 110? C., for example between 70? C. and 100? C., preferably in the vicinity of 80? C. to 85? C. With such temperatures, the duration of the treatment is for example in the range of 3 h.

[0103] Preferably, the pressure during the leaching step is the atmospheric pressure (in the range of 1 bar).

[0104] The method may include another step during which another element present in the solution to be treated and having a high added value is advantageously recovered.

[0105] In particular, upon completion of the leaching step, the cobalt, lithium and/or nickel ions will advantageously be recovered. It is also possible to recover the aluminium.

[0106] For example, it is possible to separate the nickel ions, by precipitation in a basic medium by increasing the pH between 7 and 10, by adding a base such as NaOH, NH.sub.4OH or Na.sub.2CO.sub.3, whereby the nickel is precipitated.

ILLUSTRATIVE AND NON-LIMITING EXAMPLES OF ONE EMBODIMENT

Example 1: Treatment of NMC in a (1/1/1) Ratio: Complete Dissolution of the Electrode Material and Extraction of Manganese

[0107] 16 g of a powder of a cathode material of the NMC type as well as 20 g of manganese sulphate in a powder form are immersed in 80 mL of sulphuric acid with a servo-control at pH=1 at 72? C. The solid (NMC powder)/liquid ratio is 20% (g/mL). The mixture is stirred at 400 rpm for 24 hours. Afterwards, the mixture is centrifuged and filtered, and the residual solid is washed with deionised water. Thus, it is possible to put all of the lithium, cobalt and nickel into solution after 7 hours of leaching.

[0108] FIG. 1 shows the dissolution kinetics of the NMC electrode in the sulphuric acid solution. One could notice a drop in the manganese concentration which changes from the ionic state in solution into a manganese oxyhydroxide solid whereas at the same time there is a dissolution of lithium, nickel and cobalt. When the manganese has completely reacted, the state is stationary. The mass composition of the manganese precipitate is largely enriched in Mn, with a cobalt and nickel residue. Where necessary, the manganese precipitate may be totally pure by adapting the amount of manganese sulphate.

[0109] The mass composition of the metals in the manganese residue is reported in the following table:

TABLE-US-00002 Composition (mass %) Mn Ni Co Li 51.5 2.5 3.7 0.2

Example 2: Treatment of NMC in a (6/2/2) Ratio: Complete Dissolution of the Electrode Material and Extraction of Manganese

[0110] 16 g of a powder of a cathode material of the NMC type as well as 9 g of manganese sulphate in a powder form are immersed in 80 mL of sulphuric acid with a servo-control at pH=2.5 at 100? C. The solid (NMC powder)/liquid ratio is 20% (g/mL). The mixture is stirred at 400 rpm for 24 hours. Afterwards, the mixture is centrifuged and filtered, and the residual solid is washed with deionised water. Thus, it is possible to put all of the lithium, cobalt and nickel into solution after 3 hours of leaching.

[0111] FIG. 2 shows the dissolution kinetics of the NMC electrode in the sulphuric acid solution. One could notice a decrease in manganese which passes from the ionic state in solution into a manganese oxyhydroxide solid. Simultaneously, one could observe the dissolution of lithium, nickel and cobalt. When the manganese has completely reacted, the state is stationary. The mass composition of the manganese precipitate is largely enriched in Mn, with a cobalt residue. Where necessary, the manganese precipitate may be totally pure by adapting the amount of manganese sulphate.

[0112] The mass composition of the metals in the manganese residue is reported in the following table:

TABLE-US-00003 Composition (mass %) Mn Ni Co Li 55.6 0.8 1.7 0

Example 3: Treatment of NCA: Complete Dissolution of the Electrode Material and Extraction of Manganese

[0113] 3.2 g of a powder of a cathode material of the NCA type as well as 2 g of manganese sulphate in the form of powder are immersed in 80 mL of sulphuric acid with a servo-control at pH=2 and 76? C. The solid (NCA powder)/liquid ratio is 4% (g/mL). The mixture is stirred at 400 rpm for 1 hour. Afterwards, the mixture is centrifuged and filtered, and the residual solid is washed with deionised water. The composition of the residue is analysed, and indicates a manganese precipitate with a residue of the NCA metals. Where necessary, the manganese precipitate may be totally pure by adapting the amount of manganese sulphate.

[0114] The mass composition of the metals in the manganese residue is reported in the following table:

TABLE-US-00004 Composition (mass %) Mn Ni Co Li Al 54 1.3 3.4 0.1 0.1

Example 4: Treatment of NMC in a (8/1/1) Ratio: Complete Dissolution of the Electrode Material and Extraction of Manganese

[0115] 3.2 g of NMC and 1.3 g of manganese sulphate in a powder form are immersed in 80 mL of sulphuric acid with a servo-control at pH=1 and 85? C. The solid-to-liquid ratio is 4%. The mixture is stirred at 400 rpm for 1 hour. Afterwards, the mixture is centrifuged and filtered, and the residual solid is washed with deionised water. The composition of the residue is analysed, and indicates a precipitate of manganese with traces of metals. Where necessary, the manganese precipitate may be totally pure by adapting the amount of manganese sulphate.

[0116] The mass composition of the metals in the manganese residue is reported in the following table:

TABLE-US-00005 Composition (mass %) Mn Ni Co Li Al 59.9 0.12 0.25 0.1 0.1

Example 5: Treatment of NMC in a (1/1/1) Ratio: Selective Dissolution of Nickel, Cobalt and Lithium and Extraction of Manganese with Control of the H.SUB.2.O.SUB.2 .Supply

[0117] Several tests have been carried out to study the influence of the concentration of hydrogen peroxide. The other parameters are identical for each test. The volume concentrations of hydrogen peroxide are 0% vol, 2% vol, 4% vol and 6% vol. The amount of H.sub.2O.sub.2 is transcribed in volume percentage with respect to the amount of liquid.

[0118] 8 g of NMC in the form of a powder are immersed in 80 mL of a sulphuric acid solution (pH=1), with constant servo-control to guarantee maintenance thereof. The temperature in the bath is 80? C. and the solid-to-liquid ratio is 10% (kg.Math.L.sup.?1). The mixture is stirred at 400 rpm for 24 hours. Afterwards, the mixture is centrifuged and filtered. Then the residual solid is washed with deionised water. Thus, it is possible to put all of the lithium, cobalt and nickel into solution within a few hours of leaching.

[0119] FIG. 3 shows the yield of the dissolution of the NMC electrode in the sulphuric acid solution according to the added volume percentage of H.sub.2O.sub.2 at 30%. It has been observed that not all concentrations allow achieving a complete dissolution of cobalt and nickel, and simultaneously the precipitation of manganese (i.e. absence of manganese in the solution).

[0120] For the test with the NMC 111 chemistry and for these treatment conditions, the optimum is determined at 2% by volume (arrow on the graph). For a lower concentration, the dissolution is incomplete, which is detrimental to the efficiency of the method. For a higher concentration, there is a concomitant dissolution of the manganese which does not allow removing it completely.

[0121] This example confirms the importance of the choice of the hydrogen peroxide concentration to obtain an extraction in the form of a manganese solid (% extraction of 0%) and a complete dissolution (namely 100%) for the cobalt elements, nickel and lithium.

Example 6: Treatment of NMC in a (6/2/2) Ratio: Selective Dissolution of Nickel, Cobalt and Lithium and Extraction of Manganese with Control of the H.SUB.2.O.SUB.2 .Supply

[0122] Like before, in these different tests, only the volume concentration of hydrogen peroxide is modified (0% vol, 2% vol, 4% vol and 6% vol). The amount of H.sub.2O.sub.2 is transcribed in volume percentage with respect to the amount of liquid.

[0123] 8 g of NMC in the form of a powder are immersed in 80 mL of water composed of sulphuric acid, allowing reaching a pH=1, with a constant servo-control to guarantee maintenance thereof. The temperature in the bath is 80? C. and the solid-to-liquid ratio is 10% (kg.Math.L.sup.?1). The mixture is stirred at 400 rpm for 24 hours. Afterwards, the mixture is centrifuged and filtered. Then the residual solid is washed with deionised water. Thus, it is possible to put all of the lithium, cobalt and nickel into solution within a few hours of leaching.

[0124] FIG. 4 shows the dissolution yield of the NMC electrode in the sulphuric acid solution according to the volume percentage of H.sub.2O.sub.2. One could notice an optimum for achieving a complete dissolution of cobalt and nickel, with absence of manganese in the solution. For the test with the NMC 622 chemistry and for these treatment conditions, the optimum is determined in the vicinity of 2% by volume (arrow on the graph). For this test, a person skilled in the art will adapt the amount for a totally optimised reaction. Nevertheless, one could observe that for a lower concentration, the dissolution is incomplete, which is detrimental to the efficiency of the method. For a much higher concentration, there is a concomitant dissolution of the manganese which does not allow removing it completely.

Example 7: Treatment of NMC in a (8/1/1) Ratio: Selective Dissolution of Nickel, Cobalt and Lithium and Extraction of Manganese with Control of the H.SUB.2.O.SUB.2 .Supply

[0125] This example combines five tests carried out under conditions where only the volume concentration of hydrogen peroxide changes (0% vol, 2% vol, 3% vol, 4% vol and 6% vol). The amount of H.sub.2O.sub.2 which is transcribed in volume percentage with respect to the amount of liquid.

[0126] 8 g of NMC in the form of a powder are immersed in 80 mL of water composed of sulphuric acid, allowing reaching a pH=1, with a constant servo-control to guarantee maintenance thereof. The temperature in the bath is 80? C. and the solid-to-liquid ratio is 10% (kg.Math.L.sup.?1). The mixture is stirred at 400 rpm for 24 hours. Afterwards, the mixture is centrifuged and filtered, and the residual solid is washed with deionised water. Thus, it is possible to put all of the lithium, cobalt and nickel into solution within a few hours of leaching.

[0127] FIG. 5 shows the dissolution yield of the NMC electrode in the sulphuric acid solution according to the volume percentage of H.sub.2O.sub.2. One could notice an optimum for achieving a complete dissolution of cobalt and nickel (i.e. 100%), with the absence of manganese in the solution (% extraction in solution of 0%).

[0128] For the test with the NMC 811 chemistry and for these treatment conditions, the optimum is determined in the vicinity of 3% by volume (arrow on the graph). Nevertheless, one could observe that for a lower concentration, the dissolution is incomplete, which is detrimental to the efficiency of the method. For a much higher concentration, there is a concomitant dissolution of the manganese which does not allow removing it completely.