Preparation method of lithium supplement agent suitable for solid-state battery

Abstract

The invention relates to the technical field of lithium ion battery positive electrode material preparation, in particular to a preparation method of a lithium supplement agent suitable for a solid-state battery, which comprises the following steps: dissolving a nickel source, a dopant and a lithium salt in pure water together to prepare a mixed salt solution, stirring in a reducing atmosphere, then adding an additive, and aging to obtain the lithium supplement agent suitable for the solid-state battery. Finally, preparing a precursor material by adopting a spray cracking process; then, sintering the precursor in a nitrogen atmosphere for 15-25 hours to obtain LNO, and then, mixing and sintering the nano cobaltous hydroxide and the LNO to obtain cobalt-coated LNO; and finally, in order to further improve the stability of the material, a layer of compact titanium oxide film is coated on the surface of the material by adopting a spray cracking technology, so that the high-performance lithium-supplementing composite material suitable for the solid-state battery is finally obtained. According to the method, side reaction possibly caused in the sintering process in a traditional solid phase method is avoided, the chemical stability of the product is enhanced, and therefore the overall quality and performance of the product are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of preparation of positive electrode materials for lithium-ion batteries, and in particular to a method for preparing a lithium supplement agent suitable for solid-state batteries. Background Art

[0002] Solid-state batteries, an emerging battery technology with high energy density and excellent safety, have attracted considerable attention in recent years. However, solid-state batteries inevitably experience lithium loss during cycling. This is primarily due to the severe volume expansion and contraction of the negative electrode during charge and discharge, which leads to particle pulverization, continuous damage to the solid electrolyte membrane, and continuous consumption of active lithium. Furthermore, side reactions and material structural degradation during battery cycling can also lead to a reduction in active lithium, which in turn reduces the battery's energy density and shortens its service life. To overcome these issues, lithium replenishment technology has emerged to improve battery performance by compensating for the lithium ions lost during cycling.

[0003] At present, most companies use the solid-phase method to synthesize Li2NiO2, but this method has many disadvantages, such as low product purity, high residual alkali content and insufficient chemical stability.

[0004] The development of a new lithium supplement suitable for solid-state batteries, which has a simple preparation process, low equipment requirements, and is suitable for industrial-grade large-scale preparation, is of great significance for improving the performance of solid-state batteries and promoting their industrialization. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing a lithium supplement agent suitable for solid-state batteries. The main technical problem to be solved is: to solve the shortcomings existing in solid-state battery technology, and to propose a method for preparing a lithium supplement agent suitable for solid-state batteries.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: a method for preparing a lithium supplement agent suitable for solid-state batteries, comprising the following steps:

[0007] S1. Add nickel salt crystals, doping salt crystals, and lithium salt into pure water to dissolve and prepare a mixed salt solution;

[0008] S2, adding the mixed salt solution to the reactor, introducing gas 1 to react, adding additives after the reaction is completed, and aging to obtain a precursor solution;

[0009] S3, treating the precursor solution in an inert atmosphere in a spray pyrolysis furnace at a temperature of 700-800° C. to obtain a precursor powder;

[0010] S4, sintering the precursor powder in an atmosphere furnace at 750-850°C for 15-25h to obtain Li2NiO2;

[0011] S5, mixing Li2NiO2 with nano-cobaltous hydroxide, placing the mixture in an atmosphere furnace, and sintering the mixture in an inert atmosphere at a temperature of 550-650°C to complete the cobalt coating and obtain Li2NiO2@Co;

[0012] S6. Adding the obtained Li2NiO2@Co and titanium alkoxide to ethanol to obtain a mixed solution, and passing the mixed solution into a spray cracking furnace heated to 300-500°C under the protection of an inert atmosphere for treatment, to prepare a multi-layer core-shell Li2NiO2@Co@Ti by spray cracking.

[0013] By adopting the above technical solution, a nickel source, a dopant and a lithium salt are first dissolved in pure water to prepare a mixed salt solution, which is then stirred for 1-2 hours under a reducing atmosphere, and then an additive is added and aged for 1-2 hours. Finally, a spray pyrolysis process is used to prepare a precursor material; then, the precursor is sintered at 750°C-850°C for 15-25 hours under a nitrogen atmosphere to obtain lithium-rich lithium nickelate (LNO); then, nano-cobaltous hydroxide is mixed with LNO and sintered at 550-650°C to obtain cobalt-coated LNO; finally, to further improve the stability of the material, a dense titanium oxide film is coated on its surface using spray pyrolysis technology, thereby ultimately obtaining a high-performance lithium-supplementing composite material suitable for solid-state batteries.

[0014] As a further description of the above technical solution:

[0015] In step S1, the nickel crystals are one or more of nickel nitrate, nickel oxalate, and nickel chloride; the dopant in step S1 is one or more of aluminum nitrate, zirconium nitrate, zinc nitrate, aluminum oxalate, zirconium oxalate, and aluminum chloride; and the lithium salt in step S1 is one or more of lithium hydroxide monohydrate, lithium chloride, and lithium oxalate.

[0016] As a further description of the above technical solution:

[0017] In step S2, the gas 1 is CO, and the additive in step S2 is one or more of citric acid, urea, and ammonium bicarbonate.

[0018] As a further description of the above technical solution:

[0019] The reaction temperature in step S2 is 50-70° C., the reaction pressure is 0-0.2 MPa, the reaction time is 1-2 h, and the aging time in step S2 is 1-2 h.

[0020] As a further description of the above technical solution:

[0021] The precursor powder in step S3 is a solid solution of Li2NiO2, Li2O, NiO and LiOH.

[0022] As a further description of the above technical solution:

[0023] In step S5, the nanometer cobaltous hydroxide D50 is less than 1.5 μm, BET is less than 25 μm 2 / g, content <3wt%.

[0024] As a further description of the above technical solution:

[0025] The titanium alkoxide in step S6 is one or more of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and titanium acetylacetonate. The solid content of the mixed solution in step S6 is 30±2%, and the mass fraction of the titanium alkoxide in step S6 is less than 10 wt%.

[0026] By means of the above technical solution, the method for preparing a lithium supplement for solid-state batteries of the present invention has at least the following beneficial effects:

[0027] 1. Compared with the existing technology, this method for preparing a lithium supplement for solid-state batteries uses a spray pyrolysis process to synthesize Li2NiO2. Compared with the traditional solid-phase method, it significantly improves the purity of the product, achieves a uniform mixing of nickel, doping elements and lithium, and avoids impurity residues caused by uneven mixing. At the same time, part of the H is directly removed during the spray pyrolysis process. + OH - , reducing the possibility of reaction with lithium-rich nickel oxide during sintering, effectively reducing the residual alkali content. In addition, this process also avoids the side reactions that may be triggered during the sintering process in traditional solid-phase methods, enhancing the chemical stability of the product, thereby significantly improving the overall quality and performance of the product.

[0028] 2. Compared with existing technologies, this method for preparing a lithium supplement for solid-state batteries coats the surface of Li₂NiO₂ with nano-cobaltous hydroxide, creating a highly efficient electron transport channel. This significantly promotes electron transfer between active materials, improving the battery's rate capability and charge-discharge efficiency. Furthermore, the nano-cobaltous hydroxide coating acts as an isolation layer, effectively reducing the residual alkali content of the material, improving its chemical stability and compatibility with the electrolyte, reducing the occurrence of side reactions, and extending the battery's cycle life.

[0029] 3. Compared with the existing technology, this method for preparing a lithium supplement suitable for solid-state batteries uses spray pyrolysis technology to coat a dense nano-titanium oxide film on the surface of the material, which not only further reduces the residual alkali content of the material, but also significantly improves its air stability, reduces the reaction between the material and the solid electrolyte, and improves the overall performance and safety of the solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1Schematic diagram of the Li2NiO2@Co@Ti structure proposed in the present invention;

[0031] Figure 2 This is the SEM image of the nano-cobaltous hydroxide proposed in the present invention;

[0032] Figure 3 This is the XRD pattern of Li2NiO2 proposed in the present invention;

[0033] Figure 4 This is the EDS spectrum of Li2NiO2@Co@Ti proposed in the present invention.

[0034] Legend:

[0035] 1. Li2NiO2 core; 2. Co layer; 3. Ti layer. DETAILED DESCRIPTION

[0036] Reference Figure 1-4 The present invention provides a method for preparing a lithium supplement for solid-state batteries, comprising the following steps:

[0037] S1. Adding nickel salt crystals, doping salt crystals, and lithium salt into pure water to dissolve and prepare a mixed salt solution, wherein the nickel crystals are one or more of nickel nitrate, nickel oxalate, and nickel chloride; the dopant is one or more of aluminum nitrate, zirconium nitrate, zinc nitrate, aluminum oxalate, zirconium oxalate, and aluminum chloride; and the lithium salt is one or more of lithium hydroxide monohydrate, lithium chloride, and lithium oxalate;

[0038] S2. Add the mixed salt solution to the reactor, introduce gas 1 to react, add additives after the reaction is completed, and age to obtain a precursor solution, wherein gas 1 is CO, the additive is one or more of citric acid, urea, and ammonium bicarbonate, the reaction temperature is 50-70°C, the reaction pressure is 0-0.2 MPa, the reaction time is 1-2 h, and the aging time is 1-2 h;

[0039] S3, treating the precursor solution in an inert atmosphere in a spray pyrolysis furnace at a furnace temperature of 700-800° C. to obtain a precursor powder, wherein the precursor powder is a solid solution of Li2NiO2, Li2O, NiO, and LiOH;

[0040] S4, sintering the precursor powder in an atmosphere furnace at 750-850°C for 15-25h to obtain Li2NiO2;

[0041] S5, Li2NiO2 and nano-cobalt hydroxide are mixed, placed in an atmosphere furnace, sintered under an inert atmosphere, and the temperature is controlled at 550-650 ° C to complete the cobalt coating to obtain Li2NiO2@Co, wherein the nano-cobalt hydroxide D50 <1.5μm, BET <25m 2 / g, content <3wt%;

[0042] S6. Add ethanol to the obtained Li2NiO2@Co and titanium alkoxide to obtain a mixed solution. Under the protection of an inert atmosphere, pass the mixed solution into a spray cracking furnace that has been heated to 300-500°C for treatment, and prepare multi-layer core-shell Li2NiO2@Co@Ti by spray cracking, wherein the titanium alkoxide is one or more of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and titanium acetylacetonate. The solid content of the mixed solution in step S6 is 30±2%, and the mass fraction of the titanium alkoxide in step S6 is less than 10wt%.

[0043] Example 1:

[0044] Nickelous chloride, aluminum chloride, and lithium hydroxide monohydrate were dissolved in hot pure water, controlling the gold-to-lithium ratio to be 2.05-2.10. The solution was then transferred to a reactor, set at 55°C, and carbon monoxide gas was introduced at a flow rate of 0.1 L / min for 2 hours. After the reaction, 3 wt% ammonium bicarbonate was added and the mixture was allowed to age for 2 hours to produce a precursor solution.

[0045] In a nitrogen atmosphere, the precursor solution is treated in a spray cracking furnace to generate precursor powder, and the temperature in the furnace is precisely controlled at 735°C.

[0046] The precursor powder was placed in a sagger and placed in an atmosphere furnace for sintering at 785°C for 16 hours, followed by natural cooling to finally obtain the Li2NiO2 lithium supplement.

[0047] Li2NiO2 and Co(OH)2 were mixed evenly in a weight ratio of 50:1, placed in an atmosphere furnace and sintered at 640℃ for 8 hours, and then naturally cooled to obtain Li2NiO2@Co composite material.

[0048] Li₂NiO₂@Co and tetraethyl titanate were added to an ethanol solution with a strictly controlled solid content of 30±2%, with the mass fraction of tetraethyl titanate being 5wt%. Under a nitrogen atmosphere, the precursor solution was processed in a spray pyrolysis furnace to produce a precursor powder. The furnace temperature was precisely controlled at 460°C, ultimately yielding a multilayer core-shell Li₂NiO₂@Co@Ti structure.

[0049] Example 2:

[0050] Nickelous chloride, aluminum chloride, and lithium hydroxide monohydrate were dissolved in hot pure water, controlling the gold-to-lithium ratio to be 2.05-2.10. The solution was then transferred to a reactor, set at 55°C, and carbon monoxide gas was introduced at a flow rate of 0.1 L / min for 2 hours. After the reaction, 3 wt% ammonium bicarbonate was added and the mixture was allowed to age for 2 hours to produce a precursor solution.

[0051] In a nitrogen atmosphere, the precursor solution is treated in a spray cracking furnace to generate precursor powder, and the temperature in the furnace is precisely controlled at 735°C.

[0052] The precursor powder was placed in a sagger and placed in an atmosphere furnace for sintering at 785°C for 16 hours, followed by natural cooling to finally obtain the Li2NiO2 lithium supplement.

[0053] Li2NiO2 and Co(OH)2 were mixed evenly in a weight ratio of 60:1, placed in an atmosphere furnace and sintered at 640℃ for 8 hours, and then naturally cooled to obtain Li2NiO2@Co composite material.

[0054] Li₂NiO₂@Co and tetraethyl titanate were added to an ethanol solution with a strictly controlled solid content of 30±2%, with the mass fraction of tetraethyl titanate being 5wt%. Under a nitrogen atmosphere, the precursor solution was processed in a spray pyrolysis furnace to produce a precursor powder. The furnace temperature was precisely controlled at 460°C, ultimately yielding a multilayer core-shell Li₂NiO₂@Co@Ti structure.

[0055] Example 3:

[0056] Nickelous chloride, aluminum chloride, and lithium hydroxide monohydrate were dissolved in hot pure water, controlling the gold-to-lithium ratio to be 2.05-2.10. The solution was then transferred to a reactor, set at 55°C, and carbon monoxide gas was introduced at a flow rate of 0.1 L / min for 2 hours. After the reaction, 3 wt% ammonium bicarbonate was added and the mixture was allowed to age for 2 hours to produce a precursor solution.

[0057] In a nitrogen atmosphere, the precursor solution is treated in a spray cracking furnace to generate precursor powder, and the temperature in the furnace is precisely controlled at 735°C.

[0058] The precursor powder was placed in a sagger and placed in an atmosphere furnace for sintering at 785°C for 16 hours, followed by natural cooling to finally obtain the Li2NiO2 lithium supplement.

[0059] Li2NiO2 and Co(OH)2 were mixed evenly in a weight ratio of 70:1, placed in an atmosphere furnace and sintered at 640°C for 8 hours, and then naturally cooled to obtain a Li2NiO2@Co composite material.

[0060] Li₂NiO₂@Co and tetraethyl titanate were added to an ethanol solution with a strictly controlled solid content of 30±2%, with the mass fraction of tetraethyl titanate being 5wt%. Under a nitrogen atmosphere, the precursor solution was processed in a spray pyrolysis furnace to produce a precursor powder. The furnace temperature was precisely controlled at 460°C, ultimately yielding a multilayer core-shell Li₂NiO₂@Co@Ti structure.

[0061] Example 4:

[0062] Nickelous chloride, aluminum chloride, and lithium hydroxide monohydrate were dissolved in hot pure water, controlling the gold-to-lithium ratio to be 2.05-2.10. The solution was then transferred to a reactor, set at 55°C, and carbon monoxide gas was introduced at a flow rate of 0.1 L / min for 2 hours. After the reaction, 3 wt% ammonium bicarbonate was added and the mixture was allowed to age for 2 hours to produce a precursor solution.

[0063] In a nitrogen atmosphere, the precursor solution is treated in a spray cracking furnace to generate precursor powder, and the temperature in the furnace is precisely controlled at 735°C.

[0064] The precursor powder was placed in a sagger and placed in an atmosphere furnace for sintering at 785°C for 16 hours, followed by natural cooling to finally obtain the Li2NiO2 lithium supplement.

[0065] Li2NiO2 and Co(OH)2 were mixed evenly in a weight ratio of 80:1, placed in an atmosphere furnace and sintered at 640℃ for 8 hours, and then naturally cooled to obtain Li2NiO2@Co composite material.

[0066] Li₂NiO₂@Co and tetraethyl titanate were added to an ethanol solution with a strictly controlled solid content of 30±2%, with the mass fraction of tetraethyl titanate being 5wt%. Under a nitrogen atmosphere, the precursor solution was processed in a spray pyrolysis furnace to produce a precursor powder. The furnace temperature was precisely controlled at 460°C, ultimately yielding a multilayer core-shell Li₂NiO₂@Co@Ti structure.

[0067] Example 5:

[0068] Nickelous chloride, aluminum chloride, and lithium hydroxide monohydrate were dissolved in hot pure water, controlling the gold-to-lithium ratio to be 2.05-2.10. The solution was then transferred to a reactor, set at 55°C, and carbon monoxide gas was introduced at a flow rate of 0.1 L / min for 2 hours. After the reaction, 3 wt% ammonium bicarbonate was added and the mixture was allowed to age for 2 hours to produce a precursor solution.

[0069] In a nitrogen atmosphere, the precursor solution is treated in a spray cracking furnace to generate precursor powder, and the temperature in the furnace is precisely controlled at 735°C.

[0070] The precursor powder was placed in a sagger and placed in an atmosphere furnace for sintering at 785°C for 16 hours, followed by natural cooling to finally obtain the Li2NiO2 lithium supplement.

[0071] Li2NiO2 and Co(OH)2 were mixed evenly in a weight ratio of 90:1, placed in an atmosphere furnace and sintered at 640℃ for 8 hours, and then naturally cooled to obtain Li2NiO2@Co composite material.

[0072] Li₂NiO₂@Co and tetraethyl titanate were added to an ethanol solution with a strictly controlled solid content of 30±2%, with the mass fraction of tetraethyl titanate being 5wt%. Under a nitrogen atmosphere, the precursor solution was processed in a spray pyrolysis furnace to produce a precursor powder. The furnace temperature was precisely controlled at 460°C, ultimately yielding a multilayer core-shell Li₂NiO₂@Co@Ti structure.

[0073] Comparative Case 1:

[0074] Nickelous oxide and lithium hydroxide were added to water at a gold-to-lithium ratio of 1:2.2, with the solid content controlled at 30%, and sand milled for 3 hours to obtain a precursor solution.

[0075] The precursor is dissolved and passed through a spray dryer to obtain precursor powder, and the temperature of the spray drying outlet is controlled at 105-110°C.

[0076] The precursor powder was loaded into a sagger and placed in an atmosphere furnace for sintering. The temperature was increased at 3°C / min, sintered at 200°C, 400°C, and 500°C for 1 hour, and sintered at 645°C for 12 hours. The low-purity Li2NiO2 lithium supplement was obtained by natural cooling.

[0077] The fired material was crushed by air flow mill and reloaded into the sagger for secondary sintering. The temperature was increased at 3℃ / min, sintered at 200℃, 400℃, 600℃, and 700℃ for 1h, sintered at 825℃ for 16h, and cooled naturally to obtain Li2NiO2 lithium supplement.

[0078]

[0079] Table 1

[0080] Table 1 is a comparison of the physical and chemical data of Examples 1 to 5 and Comparative Example 1.

[0081] Working principle: First, the nickel source, dopant and lithium salt are dissolved in pure water to prepare a mixed salt solution, which is stirred for 1-2 hours under a reducing atmosphere, and then additives are added and aged for 1-2 hours. Finally, a spray cracking process is used to prepare the precursor material; then, the precursor is sintered at 750℃-850℃ for 15-25 hours under a nitrogen atmosphere to obtain lithium-rich lithium nickelate (LNO). Subsequently, nano-cobaltous hydroxide is mixed with LNO and sintered at 550℃-650℃ to obtain cobalt-coated LNO; finally, to further improve the stability of the material, a dense titanium oxide film is coated on its surface using spray cracking technology, thereby finally obtaining a high-performance lithium-supplementing composite material suitable for solid-state batteries.

[0082] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a lithium supplement for solid-state batteries, characterized in that: The following steps are involved: S1. Add nickel salt crystals, doping salt crystals, and lithium salt into pure water to dissolve and prepare a mixed salt solution; S2, adding the mixed salt solution to the reactor, introducing gas 1 to react, adding additives after the reaction is completed, and aging to obtain a precursor solution; S3, treating the precursor solution in an inert atmosphere in a spray pyrolysis furnace at a temperature of 700-800° C. to obtain a precursor powder; S4, sintering the precursor powder in an atmosphere furnace at 750-850°C for 15-25h to obtain Li2NiO2; S5, mixing Li2NiO2 with nano-cobaltous hydroxide, placing the mixture in an atmosphere furnace, and sintering the mixture in an inert atmosphere at a temperature of 550-650°C to complete the cobalt coating and obtain Li2NiO2@Co; S6. Adding the obtained Li2NiO2@Co and titanium alkoxide to ethanol to obtain a mixed solution, and passing the mixed solution into a spray cracking furnace heated to 300-500°C under the protection of an inert atmosphere for treatment, to prepare a multi-layer core-shell Li2NiO2@Co@Ti by spray cracking.

2. The method for preparing a lithium supplement for solid-state batteries according to claim 1, wherein: In step S1, the nickel crystals are one or more of nickel nitrate, nickel oxalate, and nickel chloride; the dopant in step S1 is one or more of aluminum nitrate, zirconium nitrate, zinc nitrate, aluminum oxalate, zirconium oxalate, and aluminum chloride; and the lithium salt in step S1 is one or more of lithium hydroxide monohydrate, lithium chloride, and lithium oxalate.

3. The method for preparing a lithium supplement for solid-state batteries according to claim 1, wherein: In step S2, the gas 1 is CO, and the additive in step S2 is one or more of citric acid, urea, and ammonium bicarbonate.

4. The method for preparing a lithium supplement for solid-state batteries according to claim 1, wherein: The reaction temperature in step S2 is 50-70° C., the reaction pressure is 0-0.2 MPa, the reaction time is 1-2 h, and the aging time in step S2 is 1-2 h.

5. The method for preparing a lithium supplement for solid-state batteries according to claim 1, wherein: The precursor powder in step S3 is a solid solution of Li2NiO2, Li2O, NiO and LiOH.

6. The method for preparing a lithium supplement for solid-state batteries according to claim 1, wherein: In step S5, the nanometer cobaltous hydroxide D50 is less than 1.5 μm, BET is less than 25 μm 2 / g, content <3wt%.

7. The method for preparing a lithium supplement for solid-state batteries according to claim 1, characterized in that: The titanium alkoxide in step S6 is one or more of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and titanium acetylacetonate. The solid content of the mixed solution in step S6 is 30±2%, and the mass fraction of the titanium alkoxide in step S6 is less than 10 wt%.

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