Composite material for the positive electrode of a battery comprising an active material whose surface is at least partially covered with a particular material

Abstract

The present invention relates to a composite material for the positive electrode of a battery comprising at least one active material for the positive electrode, said active material comprising at least sodium and at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and mixtures thereof, the surface of which is at least partially covered with a layer of at least Na3PS4.

Description

Title of the invention: Composite material for the positive electrode of a battery comprising an active material whose surface is at least partially covered with a particular material. Technical field

[0001] The present invention relates to the field of batteries, such as Na-ion batteries, particularly all-solid-state Na-ion batteries. More specifically, the present invention relates to a particular composite material for a positive electrode. The invention also relates to a method for preparing said composite material. The present invention further relates to a positive electrode of a battery comprising said composite material, a battery cell comprising said positive electrode, a battery comprising said battery cell, and a vehicle comprising said battery. Previous techniques

[0002] Since 2006, Europe has mandated, under the Battery Directive, the recycling of at least 50% by mass of batteries, including those from the automotive sector and electric vehicle batteries. At the end of 2020, new European regulations concerning batteries and their waste were proposed, aiming to strengthen the initial measures adopted, with a requirement to achieve 65% recycling efficiency by 2024 and 70% by 2030. These regulations therefore strongly encourage the development of recycling and more efficient recycling processes.

[0003] One of the key steps common to all the processes is leaching with sulfuric acid, as well as the precipitation of metals, which generates large quantities of sodium sulfate (Na2SO4) that have not yet been reused. This sodium sulfate is also generated during the synthesis of conventional lamellar oxides, particularly after co-precipitation, to obtain, for example, materials with the formula LiNixMnyCozO2, where x, y, and z vary from 0 to 1 and the sum x + y + z equals 1. These materials are standard materials in so-called NMC-type batteries.

[0004] Moreover, the carbon present in batteries is currently very little recovered and not valorized.

[0005] On the other hand, the development of all-solid-state batteries is limited by technological advances in solid-state chemistry, particularly regarding the ionic conductors used. Indeed, the ionic conductivity properties associated with heterogeneous electrode microstructures do not yet allow for the deployment of all-solid-state technology in mobility applications, especially with regard to charging speed issues.

[0006] Thus, there is a need to develop active materials for positive electrodes to provide batteries with improved performance, but also to develop these active materials from ingredients obtained from battery recycling. Description of the invention

[0007] The invention therefore relates to a composite material for the positive electrode of a battery comprising at least one active material for the positive electrode, said active material comprising at least sodium and at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and their mixtures, the surface of which is covered at least partially with a layer of at least Na3PS4.

[0008] The composite material according to the invention makes it possible to obtain a positive electrode exhibiting improved ionic percolation. Indeed, the presence of the coating, by the layer comprising Na3PS4, improves ionic percolation within the microstructure of said electrode. The composite material according to the invention therefore has a positive impact on the battery's durability.

[0009] The invention also relates to a method for preparing a composite material as defined above, comprising:

[0010] a) the mixture of an SI solution comprising at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and their mixtures, with at least one sulfate to obtain a material Ml;

[0011] b) mixing Na2SO4 with a solution S2 comprising carbon to obtain Na2S;

[0012] c) obtaining Na2CO3 from a portion of Na2S obtained at the end of step b);

[0013] d) the calcination of Na2CO3 in the presence of the material Ml obtained at the end of step a) to obtain an active material for a positive electrode;

[0014] e) mixing a portion of Na2S obtained at the end of step b) with P2S5 to obtain a solution S 3 comprising Na3PS4;

[0015] f) mixing the S3 solution with the active material for positive electrode obtained at the end of step d) to obtain said composite material.

[0016] Another object of the invention is a positive electrode comprising at least one composite material according to the invention. The invention also relates to a battery cell comprising at least one positive electrode according to the invention, a battery comprising at least one battery cell according to the invention, and a vehicle comprising at least one battery according to the invention.

[0017] Other advantages and features of the invention will become more apparent upon examination of the detailed description.

[0018] It is specified that the expression "from... to..." used in the present description of the invention should be understood as including each of the limits mentioned.

[0019] As indicated above, the composite material for the positive electrode of a battery according to the invention comprises at least one active material for the positive electrode, the surface of which is covered at least partially with a layer of at least Na3 PS4.

[0020] Advantageously, the surface of the active material for the positive electrode is totally covered with a layer of at least Na3PS4.

[0021] Thus, the composite material according to the invention is a coated material. The active material for the positive electrode is coated with a layer of at least Na3PS4, with the surface of the active material for the positive electrode being covered at least partially, preferably totally, with a layer of at least Na3PS4.

[0022] According to a particularly preferred embodiment, the layer is a layer of Na3PS4. In this embodiment, in other words, the layer is a material consisting solely of Na3PS4.

[0023] As indicated above, said active material comprises at least sodium and at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and mixtures thereof.

[0024] Advantageously, the metal is chosen from Ni, Fe, Mn and their mixtures.

[0025] Advantageously, said layer has a thickness ranging from 5 to 200 nm, preferably from 10 to 100 nm, more preferably from 15 to 60 nm, even more preferably from 20 to 40 nm.

[0026] The present invention also relates to a method for preparing a composite material as defined above, comprising:

[0027] a) the mixture of an SI solution comprising at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and their mixtures, with at least one sulfate to obtain a material Ml;

[0028] b) mixing Na2SO4 with a solution S2 comprising carbon to obtain Na2S;

[0029] c) obtaining Na2CO3 from a portion of Na2S obtained at the end of step b);

[0030] d) the calcination of Na2CO3 in the presence of the material Ml obtained at the end of step a) to obtain an active material for a positive electrode;

[0031] e) mixing a portion of Na2S obtained at the end of step b) with P2S5 to obtain a solution S 3 comprising Na3PS4;

[0032] f) mixing the S3 solution with the active material for positive electrode obtained at the end of step d) to obtain said composite material.

[0033] This process makes it possible to obtain a composite material as defined above. The process also has the advantage of using Na2SO4 and carbon that can originate from the recycling of batteries, such as Na-ion batteries, and / or from the synthesis of lithia or sodium-based lamellar oxides.

[0034] Advantageously, step a) consists of mixing an SI solution comprising at least one metal selected from Ni, Fe, Mn and their mixtures, with at least one sulfate selected from nickel sulfate, iron sulfate, manganese sulfate and their mixtures.

[0035] According to a preferred embodiment, the process according to the invention further comprises f) an application of heat at a temperature of at least 200°C, preferably from 200 to 400°C.

[0036] Na2SO4, as indicated above, can indeed come from different sources.

[0037] It can, for example, be derived from used Na-ion batteries. A pack of used Na-ion batteries can be recovered and said Na-ion batteries can be discharged to 0 V. These batteries can come from electronic devices, such as laptops, telephones, various power tools, including screwdrivers, drills, etc., or from hybrid or electric vehicles. These batteries contain as active materials oxides of nickel, iron, manganese, cobalt, titanium, vanadium, chromium, copper, and magnesium, in particular layered oxides of nickel, iron, manganese, cobalt, titanium, vanadium, chromium, copper, and magnesium.

[0038] Then, the entire battery pack can be shredded. The resulting product can then undergo physical and mechanical separations, such as magnetic separations or flotation, to remove the plastics and / or steel. The product obtained after these steps is called black mass.

[0039] This black mass can then be leached, for example in the presence of sulfuric acid, the concentration of which can vary from 2 to 6 mol / L, and hydrogen peroxide (25 to 40% by weight).

[0040] A filtration can then be carried out to obtain two solutions, a solution SI and a solution S2.

[0041] The SI solution may comprise at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and mixtures thereof, for example at least one metal selected from Ni, Fe, Mn and mixtures thereof. In particular, the SI solution may comprise a mixture of Ni, Fe and Mn.

[0042] Solution S2 may include carbon, which may be in the form of graphite, hard carbon and / or soft carbon.

[0043] NaOH can be added to the SI solution, which can allow impurities to precipitate, and then filtration can be carried out to recover the different compounds.

[0044] During this step, a large quantity of Na2SO4 can be produced and the Na2SO4 can thus be used in step b) of the process according to the invention.

[0045] The SI solution, after filtration, can be mixed with at least one sulfate, for example, a sulfate selected from nickel sulfate, iron sulfate, manganese sulfate, cobalt sulfate, titanium sulfate, vanadium sulfate, chromium sulfate, copper sulfate, magnesium sulfate, and mixtures thereof. For example, the sulfate can be selected from nickel sulfate, iron sulfate, manganese sulfate, and mixtures thereof. In particular, the SI solution can be mixed with a mixture of three sulfates: nickel sulfate, iron sulfate, and manganese sulfate.

[0046] NaOH can also be added to this mixture.

[0047] A compound can then be precipitated and a material Ml can be obtained, by example the material NixFeyMnz(OH)2, with x, y and z being able to vary from 0 to 1, and whose sum x + y + z is equal to 1, in particular the compound Nii / 3Fei / 3Mni / 3(OH)2.

[0048] During this step, Na2SO4 can also be produced and the Na2SO4 can thus be used in step b) of the process according to the invention.

[0049] Then, Na2SO4, which can come from the various sources as discussed above, can be used to form Na2S and Na2CO3.

[0050] In particular, Na2SO4 can be mixed with the aforementioned S2 solution, comprising carbon, to obtain Na2S.

[0051] In this context, starting from Na2SO4, the Leblanc process, well known to those skilled in the art, can be used to form Na2S and Na2CO3.

[0052] Firstly, Na2S and carbon dioxide can be obtained initially.

[0053] Then, some of the Na2S is used to obtain Na2CO3. This Na2CO3 can be obtained via the Leblanc process by reaction with calcium carbonate.

[0054] Then, the Na2CO3 can be calcined in the presence of the aforementioned material Ml to obtain an active material for a positive electrode.

[0055] Calcination can be carried out at a temperature greater than or equal to 700°C, in particular from 700 to 1100°C, for example from 800 to 1000°C, in particular at 900°C, for a period greater than or equal to 1 hour, in particular from 2 to 24 hours, for example from 6 to 18 hours, in particular 12 hours.

[0056] Calcination can be followed by gentle cooling, such as cooling at about 4°C / min.

[0057] The active material for the positive electrode can be, preferably is, the active material comprising at least sodium and at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and their mixtures.

[0058] In particular, the active material may be, for example, the material NaNi / 3Fi / 3Mni / 3O 2-

[0059] In parallel, the other part of Na2S, which could be generated for example via the Leblanc process, can be used and mixed with P2S5 to obtain a solution S3 comprising Na3PS4.

[0060] The active material for the positive electrode can then be mixed with said solution S3 to obtain the composite material as defined above. A heat treatment can also be carried out to obtain the Na3PS4 crystalline phase. The heat treatment can be carried out at a temperature greater than or equal to 200°C, in particular from 200 to 400°C, for example at 300°C.

[0061] The invention also relates to a positive electrode of a battery comprising at least one composite material as defined above, and a battery cell comprising at least one positive electrode as defined above.

[0062] Another object of the present invention is a battery comprising at least one battery cell as defined above.

[0063] Preferably, the battery is a Na-ion, K-ion, Li-ion or all-solid-state battery

[0064] The present invention also relates to a vehicle comprising at least one battery as defined above.

[0065] The present invention is illustrated in a non-limiting manner by the following examples. Examples

[0066] A pack of used Na-ion batteries is recovered and the batteries are discharged to 0 V (from electronic devices such as laptops, telephones, various power tools, including screwdrivers, drills, etc., or from hybrid or electric vehicles). These batteries contain nickel, iron, and manganese oxides (including layered nickel, iron, and manganese oxides) as active materials.

[0067] Then, the entire battery pack is shredded. The resulting product then undergoes physical and mechanical separations, such as magnetic separations or flotation, to remove the plastics and / or steel. The product obtained is called black mass.

[0068] This black mass is then leached in the presence of sulfuric acid, the concentration of which can vary from 2 to 6 mol / L, and hydrogen peroxide (25 to 40% by weight). Filtration is then carried out to obtain a solution SI and a solution S2.

[0069] The SI solution comprises at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and mixtures thereof. Preferably, the SI solution comprises at least one metal chosen from Ni, Fe, Mn and their mixtures. More preferably, solution S1 comprises a mixture of Ni, Fe and Mn.

[0070] Solution S2 comprises carbon. Example 1#: Preparation of the precursor material

[0071] Aqueous solutions of NiSO4, MnSO4, and FeSO4 are added to solution 1 to obtain a total solution ratio of 1 / 3; 1 / 3; 1 / 3 Ni:Mn:Fe. The solution is then heated to 80°C, and NaOH is added to achieve a pH of 11. The compound Nii / 3Fei / 3Mni / 3(OH)2 coprecipitates and is recovered by simple filtration. During this step, Na2SO4 is generated. Example 2#: Preparation of the composite material

[0072] Na₂SO₄ was mixed with a solution S₂ containing carbon in a 1:2 molar ratio. The mixture was heated to 1000°C for 1 hour to obtain Na₂S powder. A portion of this powder was set aside for reuse during the coating process. The remaining portion was mixed with CaCO₃ at 1000°C for 1 hour. A water washing / evaporation step was then performed on the powder mixture containing Na₂CO₃ and CaS to isolate the Na₂CO₃. The Na₂CO₃ was then calcined in the presence of NiO₃,₃Fe₃,₃MnO₃,₃(OH)₂ at 900°C for 12 hours with gentle cooling (approximately 4°C / min) to obtain the active material Na₂Ni / 3Fe₃,₃MnO / 3O₂.

[0073] The first portion of Na2S was dissolved in dimethyl ether (DME) in the presence of P2S5 with a Na2S:P2S5 molar ratio of 3:1 to obtain a solution S3 containing Na3PS4. NaNi / 3Fei / 3Mni / 3O2 particles were mixed with solution S3 to obtain a NaNi / 3Fei / 3Mni / 3O2:Na3PS4 ratio of 99:1. Finally, a heat treatment was carried out at 300°C to obtain the Na3PS4 crystalline phase.

[0074] Thus, the composite material comprising the active material NaNii / 3Fei / 3Mni / 3O2 coated by a 30 nm layer of Na3PS4 was formed.

[0075] Example 3: Preparation of an all-solid-state battery

[0076] The NaNii / 3Fei / 3Mni / 3O2:Na3PS4 composite material was then mixed with Na3PS4 and carbon in the ratio 80:10:10.

[0077] The all-solid-state battery was mounted in a 10 mm diameter mold with a first densification step of the solid electrolyte Na3PS4 (80 mg at 150 MPa).

[0078] The positive electrode, composed of the composite material, Na3PS4 and carbon, was then spread on the solid electrolyte and the whole was pressed at 300 MPa.

[0079] Similarly, the anode comprising hard carbon was spread out and the whole pressed at 300 MPa.

[0080] A Na-ion all-solid-state battery with a composite material synthesized from recycling by-products has thus been manufactured.

Claims

Demands

1. Composite material for the positive electrode of a battery comprising at least one active material for the positive electrode, said active material comprising at least sodium and at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and mixtures thereof, the surface of which is at least partially covered with a layer of at least Na3PS4.

2. Composite material according to claim 1, characterized in that the surface of the active material for positive electrode is totally covered with a layer of at least Na3PS4.

3. Composite material according to claim 1 or 2, characterized in that the metal is selected from Ni, Fe, Mn and mixtures thereof.

4. Composite material according to any one of the preceding claims, characterized in that said layer has a thickness ranging from 5 to 200 nm, preferably from 10 to 100 nm, more preferably from 15 to 60 nm, even more preferably from 20 to 40 nm.

5. A method for manufacturing a composite material as defined in any one of the preceding claims, comprising: a) mixing a solution SI comprising at least one metal selected from Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg and mixtures thereof, with at least one sulfate to obtain a material M1; b) mixing Na2SO4 with a solution S2 comprising carbon to obtain Na2S; c) obtaining Na2CO3 from a portion of the Na2S obtained at the end of step b); d) calcining the Na2CO3 in the presence of the material M1 obtained at the end of step a) to obtain an active material for a positive electrode; e) mixing a portion of the Na2S obtained at the end of step b) with P2S5 to obtain a solution S3 comprising Na3PS4; f) mixing the S3 solution with the active material for the positive electrode obtained at the end of step d) to obtain said composite material.

6. A method according to the preceding claim, characterized in that step a) consists of mixing an SI solution comprising at least one metal selected from Ni, Fe, Mn and mixtures thereof, with

7.

8.

9.

10.

11. minus one sulfate chosen from nickel sulfate, iron sulfate, manganese sulfate and mixtures thereof. A method according to claim 5 or 6, characterized in that it further comprises (f) an application of heat at a temperature of at least 200°C, preferably from 200 to 400°C. Positive electrode of a battery comprising at least one composite material as defined in any one of claims 1 to 4. Battery cell comprising at least one positive electrode as defined in claim 8. Battery comprising at least one battery cell as defined in claim 9. Vehicle comprising at least one battery as defined in claim 10.