Manufacturing process for the active material for the positive electrode Li2S

Abstract

The present invention relates to a method for manufacturing the active material for positive electrode Li2S comprising: a) contacting at least one metal selected from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and mixtures thereof with at least one sulfuric acid solution to obtain a solution S1; b) purifying the solution S1; c) separating it by solvent extraction to obtain a lithium sulfate solution; d) reducing the lithium sulfate to obtain the active material for positive electrode Li2S.

Description

Title of the invention: Method for manufacturing the active material for the Li2S positive electrode. Technical field

[0001] The present invention relates to the field of batteries, such as lithium-sulfur (Li-S) batteries. More particularly, the present invention relates to a method for manufacturing the active material for the positive electrode, Li-2S. The invention also relates to a positive electrode material comprising said active material for the positive electrode, Li-2S. The present invention further relates to a positive electrode of a battery comprising said positive electrode material, a battery cell comprising said positive electrode, a battery comprising said battery cell, and a device 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. New European regulations concerning batteries and their waste were adopted in July 2023, aiming to strengthen the initial measures, with a requirement to achieve 65% recycling efficiency by 2024 and 70% by 2030. These regulations thus strongly encourage the development of recycling and more efficient recycling processes. Furthermore, quantified targets are also proposed for the recovery of cobalt, copper, nickel, and lithium (at least 90% of cobalt, nickel, and copper by 2027, rising to 95% by 2031). For lithium, the limit is set at 50% for 2027 but will then have to reach 80% in 2031. Finally, from 2031, these batteries will have to respect minimum proportions of recycled content (16% cobalt, 6% lithium and 6% nickel).From 2036 onwards, these proportions will be increased (26% cobalt, 12% lithium and 15% nickel).

[0003] Until relatively recently, the most developed battery technology was lithium-ion (Li-ion). Currently, many other technologies besides Li-ion for electrochemical energy storage are under investigation. Among these technologies is the lithium-sulfur (Li / S) system. This system has the advantage of a much higher specific energy density than current Li-ion technology. Indeed, the density of Li / S technology is around 450 Wh / kg, while that of conventional Li-ion technology is less than 300 Wh / kg.

[0004] To manufacture positive electrode materials for Li / S technology, such as lithium sulfide (Li2S), it was generally necessary to start from a source of natural lithium, such as lithium carbonate (Li2CO3) or lithium hydroxide (LiOH).

[0005] One process involving the use of these two compounds can be cited. After contacting these compounds with a sulfuric acid solution, lithium sulfate is obtained. Then, by reduction, lithium sulfide is obtained.

[0006] However, this process does not involve the use of recycled products but only natural sources of lithium, which is something we currently wish to avoid.

[0007] Various avenues for manufacturing lithium sulfide from recycled materials were then explored.

[0008] A conventional industrial process can be described. Initially, end-of-life batteries and production scraps are collected and transported to a recycling plant. While still charged, these wastes are electrically (or chemically) discharged and dismantled at the module or cell level. This step is called the pretreatment stage.

[0009] Next, several mechanical separation steps are carried out by grinding and physical separations in order to sort the material streams to obtain a concentrate of active materials, which can be called black mass (commonly called "blackmass" in English), from the negative and positive electrodes.

[0010] This black mass contains various metals, including lithium, cobalt, nickel, manganese, and also graphite. Finally, this black mass is chemically refined by hydrometallurgy to obtain compounds that can be used in batteries.

[0011] Then, this black mass undergoes various chemical treatment stages which are long and tedious.

[0012] In general, the processes that have been developed are lengthy because they involve a large number of steps during synthesis. Therefore, obtaining a positive electrode active material is more complex.

[0013] Thus, there is a need to develop a manufacturing process for the active material for the positive electrode Li2S from ingredients from battery recycling which is easy to implement, with a reduced number of steps, thus positively improving the environmental impact. Description of the invention

[0014] The invention therefore relates to a method for manufacturing the active material for a positive Li2S electrode comprising:

[0015] a) bringing at least one metal chosen from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and their mixtures into contact with at least one sulfuric acid solution to obtain a solution S1;

[0016] b) the purification of the SI solution;

[0017] c) separation by solvent extraction to obtain a lithium sulfate solution;

[0018] d) the reduction of lithium sulfate to obtain the active material for positive electrode Li2S.

[0019] The manufacturing process for the active material for the Li2S positive electrode according to the invention allows for easy implementation with direct production of lithium sulfide from ingredients that can be obtained from battery recycling. The process according to the invention also has the advantage of having a reduced number of steps, thus positively improving the environmental impact. The number of chemical reagents used is also reduced. The product obtained can also be used directly in a battery.

[0020] The invention also relates to a positive electrode material comprising at least one active positive electrode material Li2S obtained by the manufacturing process according to the invention.

[0021] Another object of the invention is a positive electrode of a battery comprising at least one positive electrode 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 device comprising at least one battery according to the invention.

[0022] Other advantages and features of the invention will become more apparent upon examination of the detailed description.

[0023] It is specified that the expression "from... to..." used in this description of the invention should be understood as including each of the limits mentioned.

[0024] As stated above, the manufacturing process according to the invention comprises:

[0025] a) contacting at least one metal selected from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and mixtures thereof with at least one sulfuric acid solution to obtain a solution SL

[0026] The metal chosen from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and their mixtures may be present in a composition.

[0027] Said composition may be a composition obtained after various steps implemented in a battery recycling process, such as that described above.

[0028] Thus, said composition can be obtained following a pretreatment step, as described above, and then after mechanical separation steps, particularly carried out by grinding and physical separations, as described above. Thus, for example, the said composition may be a concentrate of active materials, as mentioned above, which may be called black mass, originating from the negative and positive electrodes.

[0029] Said composition may thus be a composition comprising at least one metal chosen from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and their mixtures.

[0030] Advantageously, the metal is chosen from Li, Ni, Mn, Co and their mixtures.

[0031] Preferably, in step a), a composition comprising at least one metal selected from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and their mixtures is brought into contact with at least one sulfuric acid solution.

[0032] Preferably, a leaching step in a sulfuric acid solution can be carried out during step a). Thus, said composition can be dissolved by leaching in a sulfuric acid solution.

[0033] The leaching step can be carried out in a sulfuric acid (H₂SO₄) solution with a concentration ranging from 0.5 to 4 mol / L. A reducing agent, such as H₂O₂, NaHSO₃, etc., with a stoichiometric amount ranging from 0.5 to 5 mol% excess, can then be added to the solution. The solid-to-liquid ratio (S / L) can range from 10 to 300 g / L, and the duration of this step can range from 1 to 3 hours, at a temperature below 100°C.

[0034] At the end of step a), the undissolved residues can be filtered. These may be carbon compounds such as graphite.

[0035] Furthermore, at the end of step a), impurities such as copper, iron, aluminum may be found in solution.

[0036] The metal chosen from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and their mixtures can be found in the form of dissolved sulfate(s), in particular sulfate solution(s).

[0037] Preferably, the metal is chosen from Li, Ni, Mn, Co and mixtures thereof. Thus, the metal chosen from Li, Ni, Mn, Co and mixtures thereof is preferably found in the form of lithium sulfate, nickel sulfate, manganese sulfate, cobalt sulfate, in particular a mixture of said sulfates.

[0038] Furthermore, as previously stated, the process according to the invention comprises b) the purification of the SL solution

[0039] Advantageously, the purification of solution S1 is carried out by a selective precipitation step by raising pH and / or solvent extraction and / or using an ion exchange resin.

[0040] These different purification techniques are classic steps and well known to those skilled in the art.

[0041] These different techniques preferably allow the removal of the impurities mentioned above.

[0042] Furthermore, as previously stated, the process according to the invention includes c) separation by solvent extraction to obtain a lithium sulfate solution.

[0043] Separation by solvent extraction is a classic step and well known to those skilled in the art.

[0044] Solvent extraction separation preferably allows the separation of different metals, which may be found in the form of dissolved sulfate(s), as mentioned above, in particular sulfate(s) solution.

[0045] Preferably, separation by solvent extraction allows the metal or metals to be separated in order to obtain, for example, three solutions of nickel sulfate, manganese sulfate, and cobalt sulfate respectively.

[0046] Crystallization can then be carried out.

[0047] Advantageously, separation by solvent extraction also makes it possible to obtain a lithium sulfate solution.

[0048] Furthermore, as previously stated, the process according to the invention includes d) the reduction of lithium sulfate to obtain the active material for positive electrode Li2S.

[0049] Advantageously, the reduction of lithium sulfate is carried out by carboreduction in the presence of a carbon source and / or by hydrogen reduction in the presence of a dihydrogen solution.

[0050] Carboreduction can first involve the transition of lithium sulfate to a solid state, which can be achieved by a water evaporation step.

[0051] Then, carboreduction can be a reaction 1):

[0052] 1) Li2SO4 (solid) + 2C Li2S + 2 CO2.

[0053] The carbon reduction step (reaction 1) can be carried out using a carbon source as a reducing agent, in particular graphite, or even amorphous carbon. The temperature can be between 700 and 1000°C, and the duration can be between 3 h and 10 h.

[0054] The reduction to hydrogen can be a reaction 2):

[0055] 2) Li2SO4 + 4H2 -> Li2S+ 4H2O.

[0056] The hydrogen reduction (reaction 2) can be carried out using dihydrogen (H2) as the reducing agent. The temperature can be between 700 and 850°C, and the reaction can last for more than one hour.

[0057] The invention also relates to a positive electrode material comprising at least one active positive electrode material Li2S obtained by the manufacturing process according to the invention.

[0058] Another object of the invention is a positive electrode of a battery comprising at least one material for a positive electrode as defined above, and a battery cell comprising at least one positive electrode as defined above.

[0059] Another object of the present invention is a battery comprising at least one battery cell as defined above.

[0060] The present invention also relates to a device comprising at least one battery as defined above.

[0061] Said device may be any system incorporating a battery, such as for example an electric or electrified rolling vehicle, in particular a bus, a scooter, a motorcycle, an electronic device, a portable device.

[0062] The present invention is illustrated in a non-limiting manner by the following examples. Examples

[0063] End-of-life batteries and production scrap are collected and transported to a recycling plant. While still charged, this waste is electrically (or chemically) discharged and dismantled at the module or cell level. This step is called the pretreatment stage. Subsequently, several mechanical separation steps are carried out by shredding and physical separation to sort the material streams and obtain a concentrate of active materials, called black mass, from the negative and positive electrodes.

[0064] This black mass contains at least one metal, in particular at least one metal selected from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and mixtures thereof. In particular, this black mass contains various metals, including lithium, cobalt, nickel, manganese, and also graphite. Finally, this black mass is chemically refined by hydrometallurgy to obtain compounds that can be used in batteries.

[0065] Then two processes for manufacturing lithium sulfide are implemented. One is an industrial process currently in conventional use: this is the comparative process. The other is a process according to the invention. Example 1#: comparative method

[0066] This black mass is then dissolved by leaching in a sulfuric acid solution.

[0067] The leaching step is carried out in a sulfuric acid (H2SO4) solution with a concentration ranging from 0.5 to 4 mol / L. A reducing agent, such as H2O2, NaHSO3, etc., with a stoichiometric excess of between 0.5 and 5 mol%, is then added to the solution. The solid-to-liquid ratio (S / L) is 10 to 300 g / L, and the duration of this step is from 1h to 3h, at a temperature below 100°C.

[0068] Then, the undissolved residues are filtered. These are generally carbon compounds such as graphite. Impurities (notably copper, iron, aluminum) and metals, notably lithium, nickel, cobalt, and manganese in the form of dissolved sulfate, are found in solution.

[0069] The solution is then purified of these impurities by a selective precipitation step by raising the pH and / or solvent extraction and / or use of ion exchange resin.

[0070] Then, cobalt, nickel and manganese are separated by solvent extraction to obtain three separate nickel, cobalt, manganese sulfate solutions, which will then be crystallized.

[0071] The purified lithium sulfate remains in solution, which is either converted and crystallized by precipitation into lithium carbonate using sodium carbonate, or into lithium hydroxide (LiOH·H2O) using sodium hydroxide. Another possibility is to directly convert the lithium sulfate in solution into LiOH by membrane electrolysis.

[0072] These compounds are then again brought into contact with a sulfuric acid solution to obtain a lithium sulfate solution before finally obtaining, by reduction, lithium sulfide. Example 2#: method according to the invention

[0073] This black mass is then dissolved by leaching in a sulfuric acid solution. The leaching step is as specified in Example 1 above.

[0074] Then, the undissolved residues are filtered. These are generally carbon compounds such as graphite. Impurities (notably copper, iron, aluminum) and metals, notably lithium, nickel, cobalt, and manganese in the form of dissolved sulfate, are found in solution.

[0075] The solution is then purified of these impurities by a selective precipitation step by raising the pH and / or solvent extraction and / or use of ion exchange resin.

[0076] Then, cobalt, nickel and manganese are separated by solvent extraction to obtain three separate nickel, cobalt, manganese sulfate solutions, which will then be crystallized.

[0077] The purified lithium sulfate remains in solution.

[0078] Lithium sulfate then undergoes a reduction reaction, which is carried out by carboreduction in the presence of a carbon source and / or by hydrogen reduction in the presence of a dihydrogen solution.

[0079] Carboreduction first involves the transition of lithium sulfate to a solid state, which can be achieved by a water evaporation step.

[0080] Then, carboreduction can be a reaction 1):

[0081] 1) Li2SO4 (solid) + 2C Li2S + 2 CO2

[0082] The carbon reduction step (reaction 1) is carried out using a carbon source as a reducing agent, in particular graphite, or amorphous carbon. The temperature is between 700 and 1000°C, and the duration is between 3 h and 10 h.

[0083] Hydrogen reduction can be a reaction 2):

[0084] 2) Li2SO4 + 4H2 -> Li2S+ 4H2O

[0085] The hydrogen reduction (reaction 2) is carried out using dihydrogen (H2) as the reducing agent. The temperature is between 700 and 850°C, and the duration is more than one hour.

[0086] At the end of this step, the active material for the positive electrode, lithium sulfide, is obtained.

[0087] Thus, lithium sulfide was obtained using a process that allows for easy implementation with direct production of lithium sulfide from ingredients derived from battery recycling. The process according to the invention also has the advantage of having a reduced number of steps compared to the comparative process, thereby positively improving the environmental impact. The lithium sulfide obtained can also be used directly in a battery.

Claims

Demands

1. A process for manufacturing the active material for positive electrode Li2S comprising: a) contacting at least one metal selected from Li, Ni, Mn, Co, Ti, V, Cr, Fe, Cu, Mg, Al and mixtures thereof with at least one sulfuric acid solution to obtain a solution SI; b) purifying the solution S1; c) separating it by solvent extraction to obtain a lithium sulfate solution; d) reducing the lithium sulfate to obtain the active material for positive electrode Li2S.

2. The method according to claim 1, characterized in that the metal is chosen from Li, Ni, Mn, Co and mixtures thereof.

3. A process according to claim 1 or 2, characterized in that the purification of the SI solution is carried out by a selective precipitation step by raising the pH and / or extraction by solvent and / or using an ion exchange resin.

4. A process according to any one of the preceding claims, characterized in that the reduction of lithium sulfate is carried out by carboreduction in the presence of a carbon source and / or by hydrogen reduction in the presence of a dihydrogen solution.

5. Positive electrode material comprising at least one active positive electrode material Li2S obtained by the process as defined in any one of the preceding claims.

6. Positive electrode of a battery comprising at least one material as defined in claim 5.

7. Battery cell comprising at least one positive electrode as defined in claim 6.

8. Battery, such as a lithium / sulfur battery, comprising at least one battery cell as defined in claim 7.

9. Device comprising at least one battery as defined in claim 8.