Ternary precursor, positive electrode material, positive electrode, solid-state lithium battery and preparation method

Abstract

The invention relates to a ternary precursor, a positive electrode material, a positive electrode, a solid-state lithium battery and a preparation method, and relates to the technical field of lithium ion batteries, and the preparation method comprises the following steps: dissolving a nickel salt, a cobalt salt and a manganese salt in water to obtain a first mixed solution, adding an alkaline solution, a complexing agent and the first mixed solution into a reaction kettle, and carrying out a precipitation reaction to obtain a second mixed solution; after the particle size of the precipitation reaction reaches a target particle size, stopping adding the alkaline solution and the complexing agent to form a second mixed solution; removing the clear liquid of the second mixed liquid to obtain a third mixed liquid with the solid content of 40-50%; the concentration of the complexing agent in the third mixed solution is higher than that of the complexing agent in the second mixed solution; and carrying out a reaction in the third mixed solution until the solid content of the third mixed solution reaches 80% or above. The electrode material prepared from the high-nickel ternary precursor material obtained by the method disclosed by the invention is in good contact with sulfide solid electrolyte, and is high in capacity and good in rate capability and cycle performance.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a ternary precursor, a positive electrode material, a positive electrode, a solid-state lithium battery and a preparation method thereof. Background Art

[0002] To develop lithium-ion batteries with higher energy densities, sulfide solid-state batteries, using high-nickel ternary cathode materials as lithium carriers, have attracted significant attention. However, the solid-solid interface problem has long plagued the industry. Although the sulfide solid electrolyte in sulfide solid-state batteries is relatively soft, its elastic modulus remains above Tpa, making effective contact between the sulfide and cathode materials a challenge.

[0003] Existing ternary materials are primarily spherical, but the gaps between spheres are large, making pressure transmission difficult. During the mixing and electrode preparation stages, they cannot withstand full pressure, resulting in poor contact between the cathode material and the electrolyte. In light of this, the present invention provides a ternary precursor, cathode material, positive electrode, solid-state lithium battery, and preparation method. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to improve the interface contact between the positive electrode material of the sulfide solid-state battery and the sulfide solid-state battery. The purpose is to provide a ternary precursor, a positive electrode material, a positive electrode, a solid-state lithium battery and a preparation method.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: In a first aspect, a method for preparing a ternary precursor comprises the following steps: Dissolving nickel salt, cobalt salt, and manganese salt in water to obtain a first mixed solution, adding an alkaline solution, a complexing agent, and the first mixed solution to a reactor for precipitation reaction to form a second mixed solution, and stopping the addition after the particle size of the precipitation reaction reaches the target particle size; The clear liquid of the second mixed liquid is removed to obtain a third mixed liquid having a solid content of 40%-50%; the concentration of the complexing agent in the third mixed liquid is adjusted so that the concentration of the complexing agent in the third mixed liquid is higher than the concentration of the complexing agent in the second mixed liquid; and the reaction is carried out in the third mixed liquid until the solid content of the third mixed liquid reaches more than 80%, thereby obtaining a ternary precursor.

[0006] The beneficial effects of the present invention are as follows: the square ternary precursor prepared by this method solves the problem of interface contact between the positive electrode material and the sulfide in the solid-state battery, and the process does not require complex and expensive equipment and technology, has low cost, and is easy to promote on a large scale; the electrode material prepared by the high-nickel ternary precursor obtained by this method has good contact with the sulfide solid electrolyte, high capacity, and good rate performance and cycle performance.

[0007] On the basis of the above technical solution, the present invention can also be improved as follows.

[0008] Furthermore, the molar ratio of nickel ions in the nickel salt, cobalt ions in the cobalt salt, and manganese ions in the manganese salt is 88-98:1-4:2-8; Or / and, the target particle size is 2-5 microns; Or / and, the concentration of the complexing agent in the second mixed solution is 3g / L-5g / L; the concentration of the complexing agent in the third mixed solution is 6g / L-10g / L; Or / and, when adding the alkaline solution, the complexing agent and the first mixed liquid into the reactor for precipitation reaction, a first stirring speed is adopted; when reacting in the third mixed liquid, a second stirring speed is adopted; the second stirring speed is less than the first stirring speed, the first stirring speed is 600 rpm-1000 rpm, and the second stirring speed is 200 rpm-400 rpm.

[0009] The beneficial effect of adopting the above further solution is: preparing an excellent square precursor.

[0010] Furthermore, the nickel salt includes at least one of nickel sulfate, nickel chloride, and nickel nitrate; Or / and, the cobalt salt includes at least one of cobalt sulfate, cobalt chloride, and cobalt nitrate; or / and, the manganese salt comprises at least one of manganese sulfate, manganese chloride, and manganese nitrate; Or / and, the alkali in the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide; Or / and, the complexing agent includes at least one of ammonia water and ammonium sulfate.

[0011] In a second aspect, a ternary precursor is provided, wherein the ternary precursor is prepared by the preparation method.

[0012] In a third aspect, a positive electrode material is prepared from the ternary precursor.

[0013] In a fourth aspect, a method for preparing a positive electrode material comprises the following steps: Drying the ternary precursor under pressure to obtain a positive electrode material intermediate; The positive electrode material intermediate is mixed with lithium salt and sintered in an oxygen-containing atmosphere to obtain a positive electrode material.

[0014] The beneficial effect of adopting the above scheme is: preparing a square precursor positive electrode material is conducive to effective contact between the positive electrode material and the solid electrolyte.

[0015] Furthermore, the parameters of the drying process are: pressure of 3Pa-100Pa, temperature of 200°C-500°C, and holding time of 1h-10h; Or / and, the sintering parameters are: in an oxygen-containing atmosphere, the volume concentration of oxygen is 95%-100%, the temperature is 650° C.-900° C., and the sintering time is 5 h-20 h.

[0016] Or / and, the lithium salt includes at least one of lithium hydroxide and lithium carbonate; and the mass ratio of the positive electrode material intermediate to the lithium salt is 1.01-1.05.

[0017] Furthermore, the specific steps of the drying treatment are: putting the ternary precursor into a sagger, and keeping it warm for 1h-10h under the conditions of a pressure of 3Pa-100Pa and a temperature of 200℃-500℃ to obtain a positive electrode material intermediate.

[0018] A fifth aspect provides a positive electrode, wherein the positive electrode is prepared from the positive electrode material.

[0019] In a sixth aspect, a solid-state lithium battery comprises the positive electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the spherical positive electrode material of Comparative Example 1 of the present invention; Figure 2 This is a schematic diagram of a square positive electrode material according to Example 1 of the present invention; Figure 3 It is a structural schematic diagram of the sagger of the present invention.

[0021] In the accompanying drawings, the components represented by the reference numerals are as follows: 1. Spherical positive electrode material, 2. Square positive electrode material, 3. Bowl, 4. Air vent, 5. Cover, 6. Press block. DETAILED DESCRIPTION

[0022] The principles and features of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through regular channels.

[0023] This embodiment relates to a method for preparing a ternary precursor, comprising the following steps: Dissolving nickel salt, cobalt salt, and manganese salt in water to obtain a first mixed solution, adding an alkaline solution, a complexing agent, and the first mixed solution to a reactor for precipitation reaction to form a second mixed solution, and stopping the addition after the particle size of the precipitation reaction reaches the target particle size; The clear liquid of the second mixed liquid is removed to obtain a third mixed liquid having a solid content of 40%-50%, for example, a solid content of 40%, 45%, 50%, etc.; the concentration of the complexing agent in the third mixed liquid is adjusted so that the concentration of the complexing agent in the third mixed liquid is higher than the concentration of the complexing agent in the second mixed liquid; the first mixed liquid, an alkaline solution and a complexing agent are added to the third mixed liquid until the solid content of the third mixed liquid reaches more than 80%, for example, 80%, 85%, 88%, etc., to obtain a ternary precursor.

[0024] In this embodiment, the molar ratio of nickel ions in the nickel salt, cobalt ions in the cobalt salt, and manganese ions in the manganese salt is preferably 88-98:1-4:2-8, for example, 94:2:4, etc. Or / and, the target particle size is 2-5 microns, such as 2 microns, 3 microns, 4 microns, 5 microns, etc.; Or / and, the concentration of the complexing agent in the second mixed solution is 3g / L-5g / L, such as 3g / L, 4g / L, 5g / L, etc.; the concentration of the complexing agent in the third mixed solution is 6g / L-10g / L, such as 6g / L, 8g / L, 10g / L, etc.; Or / and, when adding the alkaline solution, the complexing agent and the first mixed liquid into the reactor for precipitation reaction, a first stirring speed is adopted; when carrying out the reaction in the third mixed liquid, a second stirring speed is adopted, and the second stirring speed is less than the first stirring speed, the first stirring speed is 600 rpm-1000 rpm, for example, 600 rpm, 1000 rpm, etc.; the second stirring speed is 200 rpm-400 rpm, for example, 200 rpm, 300 rpm, 400 rpm, etc.

[0025] In this embodiment, the nickel salt preferably includes at least one of nickel sulfate, nickel chloride, and nickel nitrate; Or / and, the cobalt salt includes at least one of cobalt sulfate, cobalt chloride, and cobalt nitrate; or / and, the manganese salt comprises at least one of manganese sulfate, manganese chloride, and manganese nitrate; Or / and, the alkali in the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide; Or / and, the complexing agent includes at least one of ammonia water and ammonium sulfate.

[0026] This embodiment also relates to a ternary precursor, which is prepared by the preparation method.

[0027] This embodiment also relates to a positive electrode material, which is prepared from the ternary precursor.

[0028] This embodiment also relates to a method for preparing a positive electrode material, comprising the following steps: Drying the ternary precursor under pressure to obtain a positive electrode material intermediate; The positive electrode material intermediate is mixed with lithium salt and sintered in an oxygen-containing atmosphere to obtain a positive electrode material.

[0029] In this embodiment, the parameters of the drying process are preferably: pressure of 3Pa-100Pa, such as 3Pa, 10Pa, 30Pa, 60Pa, 80Pa, 100Pa, etc.; temperature of 200°C-500°C, such as 200°C, 300°C, 400°C, 500°C, etc.; holding time of 1h-10h, such as 1h, 2h, 4h, 8h, 10h, etc.; Or / and, the sintering parameters are: in an oxygen-containing atmosphere, the oxygen concentration is 95%-100% by volume, the temperature is 650°C-900°C, for example, 650°C, 700°C, 800°C, 850°C, 900°C, etc., and the sintering time is 5h-20h, for example, 5h, 8h, 15h, 20h, etc.

[0030] Or / and, the lithium salt includes at least one of lithium hydroxide and lithium carbonate; the mass ratio of the positive electrode material intermediate to the lithium salt is 1.01-1.05, for example, 1.01, 1.03, 1.05, etc.

[0031] In this embodiment, the specific steps of the drying process are as follows: the ternary precursor is placed in a sagger, and the positive electrode material intermediate is obtained under the conditions of a pressure of 3Pa-100Pa and a temperature of 200℃-500℃, such as 10Pa, 200℃, 10Pa, 400℃, 3Pa, 500℃, etc., and the heat preservation time is 1h-10h, such as 1h, 2h, 4h, 8h, 10h, etc. The specific structure of the sagger includes a bowl body 3 and a cover body 5; the bowl body 3 and the cover body 5 can be provided with air holes 4, and the cover body 5 is provided with a pressing block 6; the pressing block 6 can apply pressure to the cover body 5, thereby applying pressure to the material in the bowl body 3; the bowl body 3 can be square ( Figure 3 ) or other shapes.

[0032] This embodiment also relates to a positive electrode, which is prepared from the positive electrode material.

[0033] This embodiment also relates to a solid-state lithium battery, which includes the positive electrode.

[0034] The present invention first controls the concentration to allow the balls to squeeze each other; then increases the content of the complexing agent to prevent the formation of new small balls / grains, allowing the gaps between the balls to continue to grow, and changing the spherical shape into a square or quasi-square shape; during the positive electrode sintering stage, pressure is used to induce the orientation of the positive electrode material, causing the primary particles to grow in the same direction (perpendicular to the pressure direction), and further grow into a square positive electrode material 2.

[0035] Therefore, the square positive electrode material 2 prepared by the method of the present invention solves the problem of interfacial contact between the positive electrode material and the sulfide in solid-state batteries. Furthermore, the process does not require complex and expensive equipment and technology, is low-cost, and is easy to promote on a large scale. The positive electrode prepared from the high-nickel ternary precursor material obtained by this method has good contact with the sulfide solid electrolyte, high capacity, and good rate performance and cycle performance. The following specific examples further illustrate this.

[0036] Example 1: A method for preparing a positive electrode material comprises the following steps: (1) Nickel sulfate, cobalt sulfate, and manganese sulfate were fully dissolved in 60°C hot water in a molar ratio of 94:2:4. After the dissolution was complete, a first mixed solution was obtained. The solution was pumped into a reactor, and sodium hydroxide solution and ammonia water were added at the same time. The ammonia value was controlled to 5g / L, the pH was 11.5, and the rotation speed was 800rpm to form a second mixed solution. The feed was stopped after the particle size D50 increased to 3.5 microns. (2) Filter the clear liquid in the second mixed liquid, control the solid content to 40%, reduce the stirring speed to 400 rpm, control the ammonia value to 10 g / L, pH to 11, continue to add the first mixed liquid, when the solid content reaches 60%, stir at 200 rpm, when the solid content reaches 80%, stop the reaction, after aging, centrifugation, washing, drying, and then remove iron by screening to prepare the high nickel precursor product. After filtering and washing, a square ternary precursor is obtained.

[0037] (3) Place the square ternary precursor into a special sagger ( Figure 3 ), under a pressure of 10 Pa, air was introduced, the temperature was controlled at 400° C. and kept warm for 5 h, and moisture was removed to obtain a square positive electrode material 2 intermediate; (4) The square positive electrode material 2 intermediate was dispersed and mixed with lithium hydroxide at an element molar ratio of 1:1.03, oxygen was introduced, and the mixture was calcined at 750°C for 12 hours to prepare the square positive electrode material 2 ( Figure 1 , S-NCM).

[0038] Comparative Example 1: A method for preparing a positive electrode material comprises the following steps: (1) Nickel sulfate, cobalt sulfate, and manganese sulfate were fully dissolved in 60°C hot water in a molar ratio of 94:2:4. After the dissolution was completed, a first mixed solution was obtained; the mixture was pumped into a reactor, and sodium hydroxide solution and ammonia water were added at the same time, and the ammonia value was controlled to be 5g / L, pH 11.5, and the rotation speed was 800rpm. After the particle size D50 increased to 3.5 microns, the feeding was stopped. After aging, centrifugation, washing, and drying, and then iron removal by screening, a high-nickel precursor product was prepared, which was filtered and washed to obtain a ternary precursor.

[0039] (2) Place the ternary precursor into a special sagger ( Figure 3 ), introduce air, control the temperature at 400°C and keep it for 5 hours, remove moisture, and obtain a positive electrode material intermediate; (3) After dispersing the cathode material intermediate, add lithium hydroxide in an element molar ratio of 1:1.03, introduce oxygen, and calcine at 750℃ for 12h to prepare the cathode material ( Figure 2 ).

[0040] Comparative Example 2: A method for preparing a positive electrode material comprises the following steps: (1) Nickel sulfate, cobalt sulfate, and manganese sulfate were fully dissolved in 60°C hot water in a molar ratio of 94:2:4. After the dissolution was complete, a first mixed solution was obtained. The solution was pumped into a reactor, and sodium hydroxide solution and ammonia water were added at the same time. The ammonia value was controlled to 5g / L, the pH was 11.5, and the rotation speed was 800rpm to form a second mixed solution. The feed was stopped after the particle size D50 increased to 3.5 microns. (2) Filter the clear liquid in the second mixed liquid, control the solid content to 40%, reduce the stirring speed to 400 rpm, control the ammonia value to 10 g / L, pH to 11, continue to add the first mixed liquid, when the solid content reaches 60%, stir at 200 rpm, when the solid content reaches 80%, stop the reaction, after aging, centrifugation, washing, drying, and then remove iron by screening to prepare the high nickel precursor product. After filtering and washing, a square ternary precursor is obtained.

[0041] (3) Place the ternary precursor into a special sagger ( Figure 3 ), introduce air, control the temperature at 400°C under normal pressure and keep it for 5 hours, remove moisture, and obtain a positive electrode material intermediate; (4) The positive electrode material intermediate was dispersed and mixed with lithium hydroxide at an element molar ratio of 1:1.03, oxygen was introduced, and the mixture was calcined at 750°C for 12 hours to prepare the positive electrode material.

[0042] Comparative Example 3: A method for preparing a positive electrode material comprises the following steps: (1) Nickel sulfate, cobalt sulfate, and manganese sulfate were fully dissolved in 60°C hot water in a molar ratio of 94:2:4. After the dissolution was completed, a first mixed solution was obtained; the mixture was pumped into a reactor, and sodium hydroxide solution and ammonia water were added at the same time, and the ammonia value was controlled to be 5g / L, pH 11.5, and the rotation speed was 800rpm. After the particle size D50 increased to 3.5 microns, the feeding was stopped. After aging, centrifugation, washing, and drying, and then iron removal by screening, a high-nickel precursor product was prepared, which was filtered and washed to obtain a ternary precursor.

[0043] (2) The ternary precursor was placed under a pressure of 10 Pa, air was introduced, the temperature was controlled at 400 ° C and kept for 5 h, and moisture was removed to obtain a cathode material intermediate; (3) The cathode material intermediate is dispersed and mixed with lithium hydroxide at an element molar ratio of 1:1.03, oxygen is introduced, and the mixture is calcined at 750°C for 12 hours to prepare the cathode material.

[0044] Test example The positive electrode materials, sulfide solid electrolyte (LSPC), and conductive agent (SuperC) of the embodiment and comparative example were weighed in a mass ratio of 70:30:5, ground and mixed evenly, and pressed into tablets in a mold battery. The negative electrode used lithium indium and the preparation pressure was 2.5T.

[0045] Cycling test: After the molded battery was placed for 10 hours, it was placed on a blue battery tester (CT2001C) for charge and discharge cycle performance testing. The test conditions were set as follows: 45°C, 2.7~4.3V (Vs Li / Li+), 1 C = 200 mAh·g -1 The cathode material's specific capacity, rate capability, and cycling performance were evaluated using a 0.05C / 0.05C half-cell test for one cycle and a 1C / 1C cycle for 100 cycles. Each experiment was repeated twice. The specific electrochemical performance is shown in Table 1 below.

[0046] Table 1 As can be seen from Table 1, the rate performance of the square positive electrode material 2 is significantly improved compared with the traditional spherical positive electrode material (1C increased by 15mAh / g), and the cycle performance is significantly improved (100 cycles increased by 7%). This is due to the fact that the square positive electrode material 2 improves its contact area with the electrolyte, which is more conducive to the performance of the rate performance. At the same time, it is helpful to prevent the contact failure between the positive electrode material and the electrolyte during the cycle, thereby increasing the cycle performance.

[0047] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a ternary precursor, characterized in that: The steps include: Dissolving nickel salt, cobalt salt, and manganese salt in water to obtain a first mixed solution, adding an alkaline solution, a complexing agent, and the first mixed solution to a reactor for precipitation reaction, and stopping adding the alkaline solution and the complexing agent after the particle size of the precipitation reaction reaches a target particle size to form a second mixed solution; The clear liquid of the second mixed liquid is removed to obtain a third mixed liquid having a solid content of 40%-50%; the concentration of the complexing agent in the third mixed liquid is adjusted so that the concentration of the complexing agent in the third mixed liquid is higher than the concentration of the complexing agent in the second mixed liquid; and the reaction is carried out in the third mixed liquid until the solid content of the third mixed liquid reaches more than 80%, thereby obtaining a ternary precursor.

2. The method for preparing a ternary precursor according to claim 1, characterized in that: The molar ratio of nickel ions in the nickel salt, cobalt ions in the cobalt salt, and manganese ions in the manganese salt is 88-98:1-4:2-8; Or / and, the target particle size is 2-5 microns; Or / and, the concentration of the complexing agent in the second mixed solution is 3g / L-5g / L; the concentration of the complexing agent in the third mixed solution is 6g / L-10g / L; Or / and, when adding the alkaline solution, the complexing agent and the first mixed liquid into the reactor for precipitation reaction, a first stirring speed is adopted; when reacting in the third mixed liquid, a second stirring speed is adopted; and the second stirring speed is less than the first stirring speed.

3. The method for preparing a ternary precursor according to claim 1, characterized in that: The nickel salt includes at least one of nickel sulfate, nickel chloride, and nickel nitrate; Or / and, the cobalt salt includes at least one of cobalt sulfate, cobalt chloride, and cobalt nitrate; or / and, the manganese salt comprises at least one of manganese sulfate, manganese chloride, and manganese nitrate; Or / and, the alkali in the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide; Or / and, the complexing agent includes at least one of ammonia water and ammonium sulfate.

4. A ternary precursor, characterized in that: The ternary precursor is prepared by the preparation method according to any one of claims 1 to 3.

5. A positive electrode material, characterized in that The positive electrode material is prepared from the ternary precursor according to claim 4.

6. A method for preparing a positive electrode material, characterized in that: The steps include: Drying the ternary precursor according to claim 4 under pressure to obtain a positive electrode material intermediate; The positive electrode material intermediate is mixed with lithium salt and sintered in an oxygen-containing atmosphere to obtain a positive electrode material.

7. The method for preparing a positive electrode material according to claim 6, characterized in that: The parameters of the drying process are: pressure of 3Pa-100Pa, temperature of 200℃-500℃, and holding time of 1h-10h; Or / and, the sintering parameters are: in an oxygen-containing atmosphere, the volume concentration of oxygen is 95%-100%, the temperature is 650° C.-900° C., and the sintering time is 5 h-20 h; Or / and, the lithium salt includes at least one of lithium hydroxide and lithium carbonate; and the mass ratio of the positive electrode material intermediate to the lithium salt is 1.01-1.

05.

8. The method for preparing a positive electrode material according to claim 6, characterized in that: The specific steps of the drying treatment are: putting the ternary precursor into a sagger, keeping the temperature at a pressure of 3Pa-100Pa and a temperature of 200°C-500°C for 1h-10h to obtain a positive electrode material intermediate.

9. A positive electrode, characterized in that The positive electrode is prepared from the positive electrode material according to claim 5.

10. A solid-state lithium battery, characterized in that: The solid-state lithium battery comprises the positive electrode according to claim 9.

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