Precursor containing decomposable ceramic material, preparation method, positive electrode material and battery

Abstract

The application provides a precursor containing decomposable ceramic material, a preparation method, a positive electrode material and a battery. The precursor containing decomposable ceramic material comprises an inner core and a shell coated on the surface of the inner core. The compactness of the inner core is greater than that of the shell. The inner core comprises decomposable ceramic material and metal doping elements. The shell comprises non-metal doping elements. The precursor containing decomposable ceramic material has a high-density region inside, uniformly dispersed with decomposable ceramic material and doped with metal doping elements, forming a high-strength compression-resistant framework. The shell is a loose porous region doped with non-metal doping elements to refine primary particles and endow the interface with flexible deformation capacity. The internal structure strength is improved, and the material has flexible interface adaptation capacity, meeting the requirements of solid-state batteries.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a precursor containing decomposable ceramic material and its preparation method, as well as a cathode material and a battery. Background Technology

[0002] High-nickel ternary cathode materials are one of the choices for cathode materials in solid-state batteries due to their high energy density. However, the manufacturing process of solid-state batteries requires high-pressure compaction of the electrodes to ensure close contact between the solid electrolyte and the active particles. This process places extremely high demands on the mechanical strength of the cathode material particles.

[0003] While existing high-nickel, large-particle-size precursor materials (D50 typically greater than 10 μm) are beneficial for improving energy density, they exhibit the following serious problems during the high-pressure compaction process of solid-state batteries: internal stress concentration within the particles, leading to easy breakage and cracking. Particle breakage not only causes deactivation of active materials but also creates new interfaces, exacerbating side reactions. More importantly, the broken particles cannot maintain good contact with the solid electrolyte, resulting in a sharp increase in interfacial impedance. Furthermore, traditional large-particle precursors lack flexible deformation capabilities, exhibiting brittle fracture rather than adaptive deformation under high pressure, failing to meet the tight solid-solid interface requirements of solid-state batteries.

[0004] Based on the above research, there is a need to provide a precursor material to solve the problems of easy internal cracking and lack of flexible interface adaptability during the high-pressure compaction process of solid-state batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a precursor containing decomposable ceramic material and its preparation method, a cathode material, and a battery. The precursor containing decomposable ceramic material has a high-density internal region with decomposable ceramic material uniformly dispersed and doped with metal dopants to form a high-strength, pressure-resistant skeleton. The outer shell is a loose, porous region doped with non-metal dopants to refine the primary particles and impart flexible deformation capability to the interface. This improves the internal structural strength and gives the material flexible interface adaptability, thus meeting the requirements of solid-state batteries.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a precursor containing a decomposable ceramic material, the precursor containing the decomposable ceramic material comprising a core and a shell covering the surface of the core, wherein the density of the core is greater than the density of the shell.

[0008] The core includes decomposable ceramic materials and metal doping elements;

[0009] The outer shell contains non-metallic doping elements.

[0010] The core of this invention has high density and uniformly dispersed decomposable ceramic material. Furthermore, the dense core is doped with metal dopants. During subsequent high-temperature sintering to prepare the cathode material, the decomposable ceramic material can be in situ transformed into a nano-ceramic reinforcing phase, synergistically forming a high-strength, pressure-resistant framework with the metal dopants. This solves the problem of internal material cracking during high-pressure compaction in solid-state batteries. The metal dopants also inhibit the shrinkage of the ceramic material, preventing internal microcracks. The enrichment of metal dopants at the ceramic framework interface forms a chemically bonded transition layer, effectively suppressing volume shrinkage during sintering and preventing internal microcracks caused by thermal stress mismatch. Simultaneously, the outer shell covering the dense core has a loose, porous structure and is doped with non-metallic dopants that refine grain size, giving the shell flexible deformation capabilities. This allows the loose, porous shell to deform during high-pressure compaction, solving the problem of poor solid-solid contact caused by the inability of the material to deform during high-pressure compaction in solid-state batteries. Therefore, the gradient structure design of the present invention, which is "soft on the outside and rigid on the inside", enables the particles to maintain the integrity of the overall structure while achieving good interfacial contact with the solid electrolyte.

[0011] Preferably, the metal doping element includes any one or a combination of at least two of Ti, Y, or W.

[0012] Preferably, the non-metallic doping element includes B.

[0013] This invention requires the use of specific metal doping elements and non-metal doping elements in order to achieve the corresponding functions of the metal doping elements and non-metal doping elements in this invention.

[0014] Preferably, the decomposable ceramic material includes any one or a combination of at least two of polycarbosilane, polyzirconoxane, or polyborosilicate.

[0015] The decomposable ceramic material described in this invention refers to a ceramic material that can decompose during the sintering process of preparing cathode materials from precursors, such as polycarbosilane, which can decompose to generate nano-SiC framework during sintering.

[0016] Preferably, with the total molar amount of metal elements in the core being 100%, the molar content of the metal dopant element is 0.2% to 1.5%, for example, it can be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4% or 1.5%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] This invention controls the amount of metal doping elements in the core, causing them to partially migrate to the ceramic framework interface during subsequent sintering, forming a composite interface layer such as Ti-C or Ti-O-Si, thereby suppressing the volume shrinkage of the ceramic material and avoiding the generation of internal microcracks.

[0018] Preferably, with the total molar amount of metal elements in the shell being 100%, the molar content of non-metallic dopant elements is 0.1% to 1.0%, for example, it can be 0.1%, 0.3%, 0.6%, 0.8% or 1.0%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, in the precursor containing decomposable ceramic material, the mass content of decomposable ceramic material is 0.5% to 3%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5% or 3%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] The amount of biodegradable ceramic material added in this invention affects the structural strength of the precursor. If the amount of biodegradable ceramic material added is too small, the structural strength of the precursor will decrease and the compressive strength will decrease. However, if the amount of biodegradable ceramic material added is too large, it will lead to the destruction of the structural integrity of the precursor, resulting in a large number of pores or cracks inside, which will impair the cycle performance of the cathode material. In addition, too much ceramic phase will hinder lithium ion migration and reduce ionic conductivity.

[0021] Preferably, in the precursor containing decomposable ceramic material (the core includes nickel-cobalt-manganese hydroxide doped with decomposable ceramic material and metal dopants, and the outer shell includes nickel-cobalt-manganese hydroxide doped with non-metal dopants), the molar ratio of nickel, cobalt, and manganese is x:y:(100-xy), where x ≥ 90, for example, it can be 90, 91, 92, 93, 94, or 95, and 2 ≤ y ≤ 8, for example, it can be 2, 3, 4, 5, 6, 7, or 8, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, the particle size D50 of the kernel is 6μm to 10μm, for example, it can be 6μm, 7μm, 8μm, 9μm or 10μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the particle size D50 of the precursor containing the decomposable ceramic material is 12μm to 20μm, for example, it can be 12μm, 14μm, 16μm, 18μm or 20μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0024] Preferably, the tap density of the precursor containing the decomposable ceramic material is 1.8 g / cm³. 3 ~2.2g / cm 3 For example, it could be 1.8 g / cm³ 3 1.9g / cm 3 2.0g / cm 3 2.1g / cm 3 Or 2.2g / cm 3 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0025] Secondly, the present invention provides a method for preparing a precursor containing a decomposable ceramic material as described in the first aspect, the method comprising the following steps:

[0026] A mixed metal salt solution, a solution containing metal dopants, a precipitant solution, a complexing agent solution, and an emulsion containing decomposable ceramic materials are passed into the base liquid to carry out the first coprecipitation reaction.

[0027] After the first coprecipitation reaction is completed, a mixed metal salt solution, a solution containing non-metallic dopants, a precipitant solution, and a complexing agent solution are continuously introduced to carry out a second coprecipitation reaction, thereby obtaining the precursor containing the decomposable ceramic material.

[0028] The stirring speed of the second coprecipitation reaction is less than that of the first coprecipitation reaction.

[0029] This invention prepares a high-strength, dense core and a flexible, porous shell through co-precipitation, and achieves doping of the core and shell, enabling uniform distribution of the doped material.

[0030] Preferably, the pH of the first coprecipitation reaction is 11.0 to 12.0, for example, 11.0, 11.2, 11.4, 11.6, 11.8 or 12.0; the temperature is 50℃ to 60℃, for example, 50℃, 52℃, 54℃, 56℃, 58℃ or 60℃; the stirring speed is 350 r / min to 420 r / min, for example, 350 r / min, 370 r / min, 390 r / min, 410 r / min or 420 r / min; and the concentration of the complexing agent in the system is 8 g / L to 10 g / L, for example, 8 g / L, 9 g / L or 10 g / L, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the concentration of the mixed metal salt solution (the molar ratio of nickel, cobalt and manganese is x:y:(100-xy), where x≥90, 2≤y≤8) is 1.5mol / L to 2.5mol / L, for example, it can be 1.5mol / L, 2.0mol / L or 2.5mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the pH of the second coprecipitation reaction is 10.5 to 11.5, for example, 10.5, 10.7, 10.9, 11.1, 11.3 or 11.5; the temperature is 50°C to 60°C, for example, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C; the stirring speed is 170 r / min to 240 r / min, for example, 170 r / min, 190 r / min, 210 r / min, 230 r / min or 240 r / min; and the concentration of the complexing agent in the system is 5 g / L to 8 g / L, for example, 5 g / L, 6 g / L, 7 g / L or 8 g / L, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the base liquid comprises water and a complexing agent, wherein the concentration of the complexing agent is 3 g / L to 5 g / L, for example, it can be 3 g / L, 4 g / L or 5 g / L, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, the solution containing the metal dopant element includes any one or a combination of at least two of the following: tetrabutyl titanate solution, titanium oxysulfate solution, or titanium tetrachloride solution.

[0035] Preferably, the solution containing non-metallic dopant elements includes any one or a combination of at least two of boric acid solution, sodium tetraborate solution, or boron oxide solution.

[0036] Preferably, the emulsion containing the biodegradable ceramic material is formed by dissolving the biodegradable ceramic material in an organic solvent (such as xylene), and then emulsifying it with an emulsifier and water. The emulsifier includes Span 80 (sorbitan monooleate). The mass ratio of the biodegradable ceramic material, organic solvent, emulsifier, and water is 1:(1.2-1.8):(0.5-1):(0.5-0.8), for example, 1:1.5:0.8:0.6, 1:1.2:1:0.5, or 1:1.8:1:0.8, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the complexing agent solution comprises ammonia water, and the precipitant solution comprises sodium hydroxide solution.

[0038] Preferably, after the second coprecipitation reaction is completed, aging, filtration, washing and drying are also carried out.

[0039] Thirdly, the present invention provides a cathode material, wherein the precursor for preparing the cathode material includes a precursor containing a decomposable ceramic material as described in the first aspect.

[0040] Fourthly, the present invention provides a method for preparing a cathode material as described in the third aspect, the method comprising the following steps:

[0041] The cathode material is obtained by mixing and sintering a precursor containing decomposable ceramic material as described in the first aspect with a lithium source.

[0042] Preferably, the molar ratio of lithium element in the lithium source to total metal element in the precursor containing decomposable ceramic material is (1.02~1.08):1, for example, it can be 1.02:1, 1.04:1, 1.06:1 or 1.08:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, the sintering method is a two-stage sintering, which includes first holding at a first temperature and then raising the temperature to a second temperature for holding.

[0044] The sintering process of this invention is divided into two stages. In the first stage, the decomposable ceramic material begins to decompose and generate a nano-framework (such as a SiC framework). Metal doping elements, such as Ti, begin to accumulate at the ceramic interface. In the second stage, the material crystal growth is completed, and at the same time, Ti and the SiC framework form a Ti-C or Ti-O-Si composite interface layer to inhibit ceramic shrinkage.

[0045] Preferably, the first temperature is 450℃~550℃, for example, it can be 450℃, 470℃, 490℃, 510℃, 530℃ or 550℃, the holding time at the first temperature is 4h~6h, for example, it can be 4h, 5h or 6h, and the heating rate to the first temperature is 2℃ / min~5℃ / min, for example, it can be 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, but is not limited to the listed values, and other unlisted values ​​within the value range are also applicable.

[0046] Preferably, the second temperature is 700℃~800℃, for example, it can be 700℃, 725℃, 750℃, 775℃ or 800℃, the holding time at the second temperature is 10h~15h, for example, it can be 10h, 12h, 14h or 15h, and the heating rate to the second temperature is 2℃ / min~5℃ / min, for example, it can be 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, but is not limited to the listed values, and other unlisted values ​​within the value range are also applicable.

[0047] Fifthly, the present invention provides a battery comprising the positive electrode material as described in the third aspect.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The precursor containing decomposable ceramic material provided by the present invention can significantly improve the compressive strength of the precursor material and solve the problem of compaction cracking: by introducing decomposable ceramic material and metal doping element such as Ti into the dense core, a dual enhancement mechanism of "nano-ceramic skeleton + Ti-reinforced interface" is formed after sintering. This high-strength compressive core can withstand the high pressure compaction in the solid-state battery manufacturing process without cracking.

[0050] (2) The precursor containing decomposable ceramic material provided by the present invention can endow the cathode material particle interface with "flexible" deformation capability: the loose porous structure on the outside can undergo a certain degree of deformation during high-pressure compaction, forming a tight fit with the solid electrolyte. At the same time, the doping of non-metallic elements such as element B refines the external primary particles (from 300~500nm to 100~200nm), further increasing the flexibility of the interface; this gradient structure design of "soft on the outside and rigid on the inside" enables the particles to maintain the integrity of the overall structure and achieve good interfacial contact with the solid electrolyte.

[0051] (3) In the precursor containing decomposable ceramic materials provided by the present invention, metal doping elements can suppress ceramic shrinkage and avoid internal microcracks: the enrichment of metal doping elements such as Ti elements at the ceramic skeleton interface forms a chemically bonded transition layer, which effectively suppresses the volume shrinkage of ceramic materials during sintering and avoids internal microcracks caused by thermal stress mismatch. Detailed Implementation

[0052] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0053] Example 1

[0054] This embodiment provides a precursor containing a decomposable ceramic material, the precursor containing the decomposable ceramic material includes a core and a shell covering the surface of the core, the density of the core is greater than the density of the shell;

[0055] The core has a particle size D50 of 8 μm and comprises a nickel-cobalt-manganese hydroxide doped with a biodegradable ceramic material and Ti. The biodegradable ceramic material is polycarbosilane, and its mass content in the precursor is 2%. The molar ratio of nickel, cobalt, and manganese is 92:4:4. Based on the total molar amount of metal elements in the core being 100%, the molar content of Ti is 0.8%.

[0056] The outer shell comprises a boron-doped nickel-cobalt-manganese hydroxide, wherein the molar ratio of nickel, cobalt, and manganese is 92:4:4, and the molar content of boron is 0.3% based on the total molar amount of metal elements in the outer shell being 100%.

[0057] The precursor containing the decomposable ceramic material has a particle size D50 of 15 μm and a tap density of 2.0 g / cm³. 3 ;

[0058] The method for preparing the precursor containing the decomposable ceramic material includes the following steps:

[0059] Deionized water and ammonia water were added to a 50L reactor as the base solution (ammonia water concentration in the base solution was 4g / L). The following steps were carried out at 55℃: Under nitrogen protection, a nickel-cobalt-manganese mixed salt solution with a total metal ion concentration of 2.0mol / L, a tetrabutyl titanate solution with a concentration of 0.1mol / L, an ammonia water solution, a NaOH solution, and a polycarbosilane emulsion were introduced into the base solution in a parallel flow to carry out the first coprecipitation reaction. The pH of the first coprecipitation reaction was controlled at 11.5, the stirring speed was 400r / min, the ammonia concentration was 9g / L, and the reaction was carried out until the particle size D50 reached 8μm.

[0060] The polycarbosilane emulsion is formed by dissolving polycarbosilane in xylene, and then emulsifying it with an emulsifier and water. The emulsifier is Span 80, and the mass ratio of polycarbosilane, xylene, emulsifier and water is 1:1.5:0.8:0.6.

[0061] The flow of tetrabutyl titanate solution and polycarbosilane emulsion was stopped. A nickel-cobalt-manganese mixed salt solution with a total metal ion concentration of 2.0 mol / L, an ammonia solution, a NaOH solution, and a boric acid solution with a concentration of 0.05 mol / L were introduced into the system to carry out a second coprecipitation reaction. The pH of the second coprecipitation reaction was controlled at 11.0, the stirring speed was 200 r / min, and the ammonia concentration was 6 g / L. The reaction was carried out until the particle size D50 reached 15 μm. Then, the mixture was aged, filtered, washed, and vacuum dried at 120 °C for 12 h to obtain the precursor containing the decomposable ceramic material.

[0062] This embodiment also provides a cathode material, the preparation method of which includes the following steps:

[0063] The precursor containing the decomposable ceramic material described in this embodiment was ball-milled with lithium carbonate in an ethanol medium at a molar ratio of lithium element to total metal element in the precursor of 1.05:1 for 3 hours. After drying, the mixture was passed through a 200-mesh sieve to obtain a mixed powder. The mixed powder was then placed in an oxygen atmosphere furnace and heated to 500°C at a heating rate of 3°C / min, held at that temperature for 5 hours, and then heated to 750°C at a heating rate of 3°C / min, held at that temperature for 12 hours to obtain the cathode material.

[0064] Example 2

[0065] This embodiment provides a precursor containing a decomposable ceramic material, the precursor containing the decomposable ceramic material includes a core and a shell covering the surface of the core, the density of the core is greater than the density of the shell;

[0066] The core has a particle size D50 of 10 μm and comprises a nickel-cobalt-manganese hydroxide doped with a biodegradable ceramic material and Ti. The biodegradable ceramic material is a polyzirconium oxane, and its mass content in the precursor is 3%. The molar ratio of nickel, cobalt, and manganese is 90:5:5. Based on the total molar amount of metal elements in the core being 100%, the molar content of Ti is 1.5%.

[0067] The outer shell comprises a boron-doped nickel-cobalt-manganese hydroxide, wherein the molar ratio of nickel, cobalt, and manganese is 90:5:5, and the molar content of boron is 0.1% based on the total molar amount of metal elements in the outer shell being 100%.

[0068] The precursor containing the decomposable ceramic material has a particle size D50 of 20 μm and a tap density of 1.8 g / cm³. 3 ;

[0069] The method for preparing the precursor containing the decomposable ceramic material includes the following steps:

[0070] Deionized water and ammonia water were added to a 50L reactor as the base solution (ammonia water concentration in the base solution was 3g / L). The following steps were carried out at 60℃: Under nitrogen protection, a nickel-cobalt-manganese mixed salt solution with a total metal ion concentration of 2.0mol / L, a titanium tetrachloride solution with a concentration of 0.1mol / L, an ammonia water solution, a NaOH solution, and a polyzirconium oxane emulsion were introduced into the base solution in parallel to carry out the first coprecipitation reaction. The pH of the first coprecipitation reaction was controlled at 12.0, the stirring speed was 350r / min, the ammonia concentration was 8g / L, and the reaction was carried out until the particle size D50 reached 10μm.

[0071] The polyzirconium oxane emulsion is formed by dissolving polyzirconium oxane in xylene, and then emulsifying it with an emulsifier and water. The emulsifier is Span 80, and the mass ratio of polyzirconium oxane, xylene, emulsifier and water is 1:1.2:1:0.5.

[0072] Stop the flow of titanium tetrachloride solution and polyzirconium oxane emulsion. In the system, introduce a mixed salt solution of nickel, cobalt and manganese with a total metal ion concentration of 2.0 mol / L, an ammonia solution, a NaOH solution, and a sodium tetraborate solution with a concentration of 0.05 mol / L to carry out a second coprecipitation reaction. Control the pH of the second coprecipitation reaction at 11.5, the stirring speed at 170 r / min, and the ammonia concentration at 5 g / L. React until the particle size D50 reaches 20 μm. Then, age, filter, wash, and vacuum dry at 120 °C for 12 h to obtain the precursor containing the decomposable ceramic material.

[0073] This embodiment also provides a cathode material, the preparation method of which includes the following steps:

[0074] The precursor containing the decomposable ceramic material described in this embodiment was ball-milled with lithium carbonate in an ethanol medium at a molar ratio of lithium to total metal elements in the precursor of 1.08:1 for 4 hours. After drying, the mixture was passed through a 200-mesh sieve to obtain a mixed powder. The mixed powder was then placed in an oxygen atmosphere furnace and heated to 550°C at a heating rate of 5°C / min, held at that temperature for 4 hours, and then heated to 800°C at a heating rate of 5°C / min, held at that temperature for 10 hours to obtain the cathode material.

[0075] Example 3

[0076] This embodiment provides a precursor containing a decomposable ceramic material, the precursor containing the decomposable ceramic material includes a core and a shell covering the surface of the core, the density of the core is greater than the density of the shell;

[0077] The core has a particle size D50 of 6 μm and comprises a nickel-cobalt-manganese hydroxide doped with a biodegradable ceramic material and Ti. The biodegradable ceramic material is polycarbosilane, and its mass content in the precursor is 0.5%. The molar ratio of nickel, cobalt, and manganese is 92:4:4. Based on the total molar amount of metal elements in the core being 100%, the molar content of Ti is 0.2%.

[0078] The outer shell comprises a boron-doped nickel-cobalt-manganese hydroxide, wherein the molar ratio of nickel, cobalt, and manganese is 92:4:4, and the molar content of boron is 1.0% based on the total molar amount of metal elements in the outer shell being 100%.

[0079] The precursor containing the decomposable ceramic material has a particle size D50 of 12 μm and a tap density of 2.2 g / cm³. 3 ;

[0080] The method for preparing the precursor containing the decomposable ceramic material includes the following steps:

[0081] Deionized water and ammonia water were added to a 50L reactor as the base solution (ammonia water concentration of 5g / L in the base solution). The following steps were carried out at 50℃: Under nitrogen protection, a nickel-cobalt-manganese mixed salt solution with a total metal ion concentration of 2.0mol / L, a tetrabutyl titanate solution with a concentration of 0.1mol / L, an ammonia water solution, a NaOH solution, and a polycarbosilane emulsion were introduced into the base solution in a parallel flow to carry out the first coprecipitation reaction. The pH of the first coprecipitation reaction was controlled at 11.0, the stirring speed was 420r / min, the ammonia concentration was 10g / L, and the reaction was carried out until the particle size D50 reached 6μm.

[0082] The polycarbosilane emulsion is formed by dissolving polycarbosilane in xylene, and then emulsifying it with an emulsifier and water. The emulsifier is Span 80, and the mass ratio of polycarbosilane, xylene, emulsifier and water is 1:1.8:1:0.8.

[0083] The flow of tetrabutyl titanate solution and polycarbosilane emulsion was stopped. A nickel-cobalt-manganese mixed salt solution with a total metal ion concentration of 2.0 mol / L, an ammonia solution, a NaOH solution, and a boric acid solution with a concentration of 0.05 mol / L were introduced into the system to carry out a second coprecipitation reaction. The pH of the second coprecipitation reaction was controlled at 10.5, the stirring speed was 240 r / min, and the ammonia concentration was 8 g / L. The reaction was carried out until the particle size D50 reached 12 μm. Then, the mixture was aged, filtered, washed, and vacuum dried at 120 °C for 12 h to obtain the precursor containing the decomposable ceramic material.

[0084] This embodiment also provides a cathode material, the preparation method of which includes the following steps:

[0085] The precursor containing the decomposable ceramic material described in this embodiment was ball-milled with lithium carbonate in an ethanol medium at a molar ratio of lithium element to total metal element in the precursor of 1.02:1 for 2 hours. After drying, the mixture was passed through a 200-mesh sieve to obtain a mixed powder. The mixed powder was then placed in an oxygen atmosphere furnace and heated to 450°C at a heating rate of 2°C / min, held at that temperature for 6 hours, and then heated to 700°C at a heating rate of 2°C / min, held at that temperature for 15 hours to obtain the cathode material.

[0086] Example 4

[0087] This embodiment provides a precursor containing decomposable ceramic material. Except that the mass content of the decomposable ceramic material in the precursor is 0.25%, the precursor containing the decomposable ceramic material is the same as that in Embodiment 1.

[0088] This embodiment also provides a cathode material. The preparation method of the cathode material is the same as that of Example 1, except that it uses the precursor of this embodiment.

[0089] Example 5

[0090] This embodiment provides a precursor containing decomposable ceramic material. Except for the fact that the mass content of the decomposable ceramic material in the precursor is 4%, the precursor containing the decomposable ceramic material is the same as that in Embodiment 1.

[0091] This embodiment also provides a cathode material. The preparation method of the cathode material is the same as that of Example 1, except that it uses the precursor of this embodiment.

[0092] Example 6

[0093] This embodiment provides a precursor containing decomposable ceramic material, which is the same as that in Embodiment 1 except that the molar content of Ti is 0.1%.

[0094] This embodiment also provides a cathode material. The preparation method of the cathode material is the same as that of Example 1, except that it uses the precursor of this embodiment.

[0095] Example 7

[0096] This embodiment provides a precursor containing decomposable ceramic material. Except for the molar content of Ti being 2.5%, the precursor containing decomposable ceramic material is the same as that in Embodiment 1.

[0097] This embodiment also provides a cathode material. The preparation method of the cathode material is the same as that of Example 1, except that it uses the precursor of this embodiment.

[0098] Comparative Example 1

[0099] This comparative example provides a precursor that is identical to that of Example 1, except that the core does not contain decomposable ceramic material.

[0100] This comparative example also provides a cathode material, the preparation method of which is the same as that of Example 1, except that the precursor of this comparative example is used.

[0101] Comparative Example 2

[0102] This comparative example provides a precursor that is identical to that of Example 1, except that it does not include Ti in the core.

[0103] This comparative example also provides a cathode material, the preparation method of which is the same as that of Example 1, except that the precursor of this comparative example is used.

[0104] Comparative Example 3

[0105] This comparative example provides a precursor that is identical to that of Example 1, except that the shell does not contain boron.

[0106] This comparative example also provides a cathode material, the preparation method of which is the same as that of Example 1, except that the precursor of this comparative example is used.

[0107] Comparative Example 4

[0108] This comparative example provides a precursor, which is identical to that of Example 1 except that the biodegradable ceramic material is replaced by a non-biodegradable ceramic material (specifically silicon carbide).

[0109] This comparative example also provides a cathode material, the preparation method of which is the same as that of Example 1, except that the precursor of this comparative example is used.

[0110] The positive electrode materials obtained in the above embodiments and comparative examples were used to prepare solid-state batteries. The preparation process is as follows: the positive electrode active material, binder, and additives were mixed, heated, and sheared. The mixture was then calendered into sheets and bonded to a current collector to obtain a positive electrode sheet. Subsequently, the prepared positive electrode sheet was stacked and assembled with a negative electrode sheet and a solid electrolyte layer (or by in-situ polymerization, injection of a precursor solution, and heating to cure). The solid-state battery was obtained through stamping, encapsulation, and other processes. The electrochemical performance of the prepared solid-state battery was tested under the following conditions: the first charge-discharge voltage range was 2.0-4.8V, and the charge-discharge test was conducted at a rate of 0.1C.

[0111] The test results are shown in Table 1 below:

[0112] Table 1

[0113]

[0114] As can be seen from Table 1 above:

[0115] As shown in Example 1 and Comparative Examples 1-2, in the precursor containing decomposable ceramic material provided by the present invention, the decomposable ceramic material and the metal dopant can form a dual enhancement mechanism of "nano-ceramic framework + reinforced interface" after sintering. The two work synergistically to increase the strength of the cathode material, thereby preventing the cathode material from cracking during solid-state battery fabrication and improving the performance of the solid-state battery. As shown in Example 1 and Comparative Example 3, the doping of B in the shell of the present invention can refine the primary particles of the shell, enhance interface flexibility, and thus enhance the solid-solid contact effect. As shown in Example 1 and Comparative Example 4, the core of the present invention is doped with decomposable ceramic material, which, compared to non-decomposable ceramic material... Ceramic materials can cause rigid interfaces to fail. During cycling, volume changes can lead to slippage, blocking ion channels. Furthermore, silicon carbide is non-deformable during charge and discharge, resulting in excessive local stress and cracks. The core advantage of in-situ decomposition ceramics lies in the ability to pre-determine volume shrinkage, enabling dynamic adjustment of the internal structure of the cathode, rather than simply using fillers. As shown in Examples 1 and 4-5, this invention preferably adds a specific amount of decomposable ceramic material to ensure the overall performance of the solid-state battery. As shown in Examples 1 and 6-7, this invention preferably adds a specific amount of Ti to suppress the shrinkage of ceramic materials and further improve the performance of the solid-state battery.

[0116] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A precursor containing a biodegradable ceramic material, characterized in that, The precursor containing decomposable ceramic material includes a core and a shell covering the surface of the core, wherein the density of the core is greater than that of the shell. The core includes decomposable ceramic materials and metal doping elements; The outer shell contains non-metallic doping elements.

2. The precursor containing decomposable ceramic material according to claim 1, characterized in that, The metal doping element includes any one or a combination of at least two of Ti, Y, or W; Preferably, the non-metallic doping element includes B; Preferably, the decomposable ceramic material includes any one or a combination of at least two of polycarbosilane, polyzirconoxane, or polyborosilicate.

3. The precursor containing decomposable ceramic material according to claim 1 or 2, characterized in that, With the total molar amount of metal elements in the core being 100%, the molar content of the metal dopant element is 0.2% to 1.5%. Preferably, with the total molar amount of metallic elements in the shell being 100%, the molar content of non-metallic dopant elements is 0.1% to 1.0%. Preferably, in the precursor containing decomposable ceramic material, the mass content of decomposable ceramic material is 0.5% to 3%; Preferably, in the precursor containing decomposable ceramic material, the molar ratio of nickel, cobalt and manganese is x:y:(100-xy), where x≥90 and 2≤y≤8.

4. The precursor containing decomposable ceramic material according to claim 1 or 2, characterized in that, The particle size D50 of the core is 6μm~10μm; Preferably, the particle size D50 of the precursor containing the decomposable ceramic material is 12 μm to 20 μm; Preferably, the tap density of the precursor containing the decomposable ceramic material is 1.8 g / cm³. 3 ~2.2g / cm 3 .

5. A method for preparing a precursor containing a decomposable ceramic material as described in any one of claims 1-4, characterized in that, The method for preparing the precursor containing the decomposable ceramic material includes the following steps: A mixed metal salt solution, a solution containing metal dopants, a precipitant solution, a complexing agent solution, and an emulsion containing decomposable ceramic materials are passed into the base liquid to carry out the first coprecipitation reaction. After the first coprecipitation reaction is completed, a mixed metal salt solution, a solution containing non-metallic dopants, a precipitant solution, and a complexing agent solution are continuously introduced to carry out a second coprecipitation reaction, thereby obtaining the precursor containing the decomposable ceramic material. The stirring speed of the second coprecipitation reaction is less than that of the first coprecipitation reaction.

6. The method for preparing a precursor containing decomposable ceramic material according to claim 5, characterized in that, The pH of the first coprecipitation reaction is 11.0~12.0, the temperature is 50℃~60℃, the stirring speed is 350r / min~420r / min, and the concentration of the complexing agent in the system is 8g / L~10g / L; Preferably, the concentration of the mixed metal salt solution is 1.5 mol / L to 2.5 mol / L; Preferably, the pH of the second coprecipitation reaction is 10.5~11.5, the temperature is 50℃~60℃, the stirring speed is 170r / min~240r / min, and the concentration of the complexing agent in the system is 5g / L~8g / L; Preferably, the base liquid comprises water and a complexing agent, wherein the concentration of the complexing agent is 3 g / L to 5 g / L.

7. A positive electrode material, characterized in that, The precursor for preparing the cathode material includes the precursor containing a decomposable ceramic material as described in any one of claims 1-4.

8. A method for preparing the cathode material as described in claim 7, characterized in that, The method for preparing the cathode material includes the following steps: The cathode material is obtained by mixing and sintering a precursor containing a decomposable ceramic material as described in any one of claims 1-4 and a lithium source.

9. The method for preparing the cathode material according to claim 8, characterized in that, The molar ratio of lithium in the lithium source to the total metal elements in the precursor containing decomposable ceramic materials is (1.02~1.08):1; Preferably, the sintering method is a two-stage sintering, which includes first holding at a first temperature, and then raising the temperature to a second temperature for holding. Preferably, the first temperature is 450℃~550℃, the holding time at the first temperature is 4h~6h, and the heating rate to the first temperature is 2℃ / min~5℃ / min; Preferably, the second temperature is 700℃~800℃, the holding time at the second temperature is 10h~15h, and the heating rate to the second temperature is 2℃ / min~5℃ / min.

10. A battery, characterized in that, The battery includes the positive electrode material as described in claim 7.

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