CN112635752A - Ternary cathode material, preparation method thereof and lithium battery - Google Patents
Ternary cathode material, preparation method thereof and lithium battery Download PDFInfo
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Abstract
The invention relates to a ternary cathode material, which is a single-crystal high-nickel ternary cathode material with the chemical formula of LiaNixCoyMnzO2, the single crystal type high nickel ternary anode material simultaneously satisfies: when the cumulative particle size distribution number reaches 10%, the corresponding primary particle diameter D10 is not less than 4.1 μm, the average primary particle diameter D50 is not less than 9.5 μm, and the cumulative particle diameterWhen the degree distribution number reaches 90%, the corresponding primary particle diameter D90 is not less than 17.5 um. The invention also relates to a method for preparing the ternary cathode material, which comprises the following steps: by ball milling NiO, MnO and Co3O4Preparing a single-phase rock salt ternary precursor by using the powder, wherein the submicron single-phase rock salt ternary precursor is a solid solution; and (3) calcining the single-phase rock salt ternary precursor in mixed molten salt at high temperature, wherein the mixed molten salt comprises a Li compound and inorganic salt. The invention also relates to a lithium battery which comprises the ternary cathode material.
Description
Technical Field
The invention relates to the field of lithium ion battery materials, in particular to a ternary cathode material, a preparation method thereof and a lithium battery using the ternary cathode material.
Background
Lithium ion secondary batteries have been widely used in the fields of consumer electronics, electric vehicles, communications, and the like, and lithium ion secondary batteries suitable for electric vehicles are required to have high power and high capacity. The battery anode material is the core part of the lithium ion secondary battery, and directly determines the energy density, the power density, the safety index and the cost of the lithium ion secondary battery. A lithium cobalt-based composite oxide, which is a layered composite oxide as a positive electrode material for a battery, can obtain a high voltage of 4V class and has a high energy density, but since cobalt as a raw material thereof is scarce and expensive, it is necessary to develop a composite oxide having a small cobalt content, and a layered structure high nickel low cobalt ternary positive electrode material (LiNi)xCoyMn1-x-yO2X is more than or equal to 0.6) can provide high energy density and power density.
The reason for the wide use of the layered-structure high-nickel low-cobalt ternary cathode material is the microstructure and morphology of the material. The microstructure of the ternary material prepared by the prior technical scheme is secondary sphere-like polycrystalline particles formed by agglomeration and sintering of nanoscale primary particles, and the special microstructure causes the following technical problems: 1. the skeleton firmness of the secondary sphere structure is poor, and high compaction density (lower than that of the lithium cobaltate cathode material with the layered structure) cannot be realized. Under the condition of higher compaction density, the secondary sphere structure is easy to break, internal particles and more internal surface areas are exposed, so that the material can seriously react with electrolyte when being charged to a high-voltage state, the dissolution of metal ions is intensified, the performance attenuation is accelerated, gas generation is serious, and larger potential safety hazard is formed; 2. the primary nano small particles forming the secondary ball are easy to generate interface pulverization and even crack due to the anisotropic volume change among the primary nano small particles in the charging and discharging processes, so that the secondary ball structure collapses, and more side reactions and electrochemical performance attenuation are initiated; 3. the high-nickel ternary material (the nickel content is more than or equal to 60 percent) has strong surface reactivity and generally needs surface modification and coating treatment. The structure and morphology of the secondary spheres lead to coating difficulties, especially in the case of inner particles which cannot be coated. Once the structure of the secondary sphere collapses due to mechanical or electrochemical reasons, severe side reactions between the exposed inner particles and the electrolyte may occur, resulting in performance degradation.
In order to solve the technical problems, the prior technical scheme is to make a ternary cathode material into single crystal large-size particles. Compared with the polycrystalline secondary sphere ternary material, the single crystal ternary material has the following advantages: 1. high mechanical strength and high compaction density (3.7 g/cm)3Above). The high compaction density is beneficial to reducing the internal resistance of the electrode, reducing ohmic polarization and increasing the volume energy density of the battery; 2. the specific surface area of the primary single crystal particles is small, so that the side reaction with the electrolyte is effectively reduced, the gas production is inhibited, and the safety is high; 3. the integral structure of the primary single crystal particles is relatively stable, and the service life of the battery is long; 4. the surfaces of the single crystal particles are smooth, so that the single crystal particles are beneficial to fully contacting and coating the conductive carbon material; 5. the single crystal structure is more beneficial to lithium ion transmission in the material (the primary particles in the polycrystalline secondary spherical particles are not grain boundaries, and generally have smaller gaps, so that lithium ions cannot pass through the gaps). However, this solution is only applicable to certain low-nickel ternary materials (e.g. LiNi)1/3Mn1/3Co1/3O2And LiNi0.5Mn0.3Co0.2O2) But is not suitable for a layered structure high-nickel low-cobalt ternary cathode material (LiNi)xCoyMn1-x-yO2，x≥0.6)。
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a ternary cathode material and a preparation method thereof.
On one hand, the invention provides a ternary cathode material which is a single-crystal high-nickel ternary cathode material with a chemical formula of LiaNixCoyMnzO2Wherein a is more than or equal to 1.06 and less than or equal to 1.10, x is more than or equal to 0.8 and less than or equal to 0.9, y is more than or equal to 0.01 and less than or equal to 0.15, and z is 1-x-y. The ternary cathode material simultaneously satisfies the following conditions: the particle size distribution reaches 10%, the corresponding primary particle size D10 is not less than 4.1 μm, the average primary particle size D50 is not less than 9.5 μm, and the cumulative particle size distribution reaches 90%, the corresponding primary particle size D90 is not less than 17.5 um.
In another aspect, the invention provides a method for preparing the single-crystal high-nickel ternary cathode material, which comprises the following steps: by ball milling NiO, MnO and Co3O4Preparing a single-phase rock salt ternary precursor by using powder, wherein the submicron single-phase rock salt ternary precursor is a solid solution; and (2) calcining the single-phase rock salt ternary precursor in mixed molten salt at high temperature, wherein the mixed molten salt comprises a Li compound and an inorganic salt, the molar ratio of the inorganic salt to the Li compound is 1-2:8, and the molar ratio of the Li compound to the single-phase rock salt ternary precursor is more than 2.
Wherein the inorganic salt can be conventional inorganic salt in the art, and can be inorganic salt capable of melting, and the inorganic salt is A2SO4, B-X and YSO4A is Li, Na, K, Rb or Cs, B is Li, Na, K, Rb or Cs, X is F, Cl, Br, I or NO3And Y is Mg, Ca, Sr or Ba. .
Among them, the Li compound may be a Li compound that is conventional in the art. In one embodiment, the Li compound is LiOH and the inorganic salt is Na2SO4。
Wherein the high-temperature calcination comprises primary high-temperature calcination and secondary high-temperature calcination, the time of the primary high-temperature calcination is 5-10h, and the temperature of the primary high-temperature calcination is 380-450 ℃; directly raising the temperature after the primary high-temperature calcination for secondary high-temperature calcination, wherein the time of the secondary high-temperature calcination is 12-18 h, and the temperature of the secondary high-temperature calcination is 950-980 ℃. And after secondary high-temperature calcination, naturally cooling to room temperature, washing and drying to obtain the single-crystal high-nickel ternary cathode material.
The method for preparing the single-crystal high-nickel ternary cathode material is dry synthesis, and compared with the existing coprecipitation method, the dry synthesis can realize 100% of raw materials (NiO, MnO and Co)3O4) The utilization rate is high, and the single crystal type high nickel ternary anode material with high crystallinity can be prepared.
On the other hand, the invention also provides the application of the ternary cathode material in the preparation of lithium ion batteries. The positive electrode of the lithium ion battery comprises a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer is formed on the surface of the positive electrode current collector, and the positive electrode active material layer contains the single-crystal high-nickel ternary positive electrode material.
Compared with the prior art, the technical scheme of the invention has at least the following beneficial effects:
1. single crystal positive electrode materials consist of one or several large grains, whereas traditional polycrystalline materials are typically spherical aggregates of many sub-crystallites. Particle comminution in polycrystalline positive electrode materials is one of its more common failure modes, leading to active material spallation and increased surface area, which is particularly evident in high nickel ternary positive electrode materials. Therefore, the single-crystal high-nickel ternary cathode material provided by the invention can effectively improve the cycle performance of the lithium ion battery.
2. In commercial lithium ion batteries, both polycrystalline and single crystal positive electrode material precursors are synthesized by coprecipitation. However, the process requires precise control of concentration, temperature, feed rate, pH, stirring intensity, etc., and the resulting product has a high sulfur content, is expensive, and is environmentally unfriendly. Compared with NMC anode powder prepared by a coprecipitation method, the dry synthesis provided by the invention can realize 100% of raw material utilization rate, and the method is simple, low in cost and compatible with the existing ternary material synthesis equipment and conditions.
3. Compared with the existing high-nickel ternary cathode material, the single-crystal high-nickel ternary cathode material prepared by the preparation method disclosed by the invention has the advantages of good crystallinity, higher charge-discharge capacity, smaller discharge capacity attenuation rate, higher gram capacity, excellent cycle performance, better rate performance, higher thermal runaway temperature, higher first effect, smaller heat release and higher safety.
The following description will be given with reference to examples.
Drawings
The figures further illustrate the invention, but the examples in the figures do not constitute any limitation of the invention.
Fig. 1 is a particle size distribution diagram of a ternary cathode material provided in example 1 of the present invention.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
The present embodiment provides a lithium ion secondary battery whose positive electrode includes a positive electrode collector and a positive electrode active material layer formed on a surface of the positive electrode collector. The negative electrode of the lithium ion secondary battery includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is formed on the surface of the negative electrode current collector. The lithium ion secondary battery provided in the present example is a laminated battery, that is, a structure in which a positive electrode, a separator, and a negative electrode are laminated. The positive electrode has a structure in which positive electrode active material layers are coated on both surfaces of a positive electrode current collector. The negative electrode has a structure in which a negative electrode active material layer is coated on both surfaces of a negative electrode current collector. The positive electrode active material layer and the negative electrode active material layer adjacent thereto sandwich a separator. The separator has a function of holding an electrolyte to ensure lithium ion conductivity between the positive electrode and the negative electrode, and a function as a partition wall between the positive electrode and the negative electrode. The separator is a microporous membrane. In this embodiment, the electrolyte is a liquid electrolyte or a gel polymer electrolyte.
The positive active material layer contains single crystal type high nickel ternary positive electrode material with chemical formula of Li1.06Ni0.8Co0.15Mn0.05O2The primary particle size distribution of the single crystal type high nickel ternary positive electrode material is shown in fig. 1, wherein the primary particle size D10 ═ 4.137 μm corresponding to a cumulative particle size distribution number of 10%, the average primary particle size D50 ═ 9.503 μm, and the primary particle size D90 ═ 17.63um corresponding to a cumulative particle size distribution number of 90%. The single crystal type high nickel ternary positive electrode material has a uniform distribution of primary particle size, can prevent deterioration of an electrode due to non-uniformity of voltage in the electrode surface, and can improve cycle characteristics of a lithium ion secondary battery.
In the positive active material layer, the weight of the single crystal type high nickel ternary positive material accounts for 85-95% of the total weight of the positive active material, and the positive active material layer further comprises a conductive auxiliary agent and a binder. The negative electrode active material layer includes a negative electrode active material, a conductive auxiliary agent, and a binder. The negative electrode active material is one or more of carbon materials such as graphite, soft carbon, hard carbon, lithium-transition metal composite oxide, metal materials and lithium alloy negative electrode materials.
The conductive aid and the binder in the positive electrode active material layer and the conductive aid and the binder in the negative electrode active material layer may be the same or different.
Among them, the binder is not particularly limited, and conventional binders applied to lithium ion batteries such as polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyacrylonitrile, polyimide, polyamide, cellulose, carboxymethyl cellulose and salts thereof, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene fluoride, styrene-butadiene rubber, and the like can be used. The conductive auxiliary agent is an additive to be added for improving the conductivity of the positive electrode active material layer or the negative electrode active material layer. The conductive auxiliary agent can be carbon black such as ketjen black and acetylene black, and carbon materials such as graphite and carbon fiber.
Example 2
This embodiment provides a lithium battery, which is an all-solid-state battery including a positive electrode sheet including a positive electrode collector and a positive electrode active material layer containing a single-crystal type high-nickel ternary positive electrode material, a chemical composition thereof, a negative electrode sheet, and an electrolyte layerIs represented by the formula Li1.1Ni0.9Co0.01Mn0.09O2。
Example 3
This example provides a ternary cathode material, which is a single-crystal high-nickel ternary cathode material having a chemical formula of LiaNixCoyMnzO2Wherein a is more than or equal to 1.05 and less than or equal to 1.08, x is more than or equal to 0.85 and less than or equal to 0.88, y is more than or equal to 0.10 and less than or equal to 0.14, and z is 1-x-y. The composition of each element can be measured by Inductively Coupled Plasma (ICP) emission spectrometry, for example.
The ternary positive electrode material provided in this example had a layered crystal structure in which lithium atomic layers and transition metal (Mn, Ni, and Co are arranged in a correct order) atomic layers are alternately stacked with oxygen atomic layers interposed therebetween,
the transition metal contributes to capacity and power characteristics from the viewpoint of improving the purity of the material and improving the electron conductivity. Conventional NMC (e.g., LiNi) from the viewpoint of cycle characteristics0.5Mn0.3Co0.2O2) When the metal composition of nickel, manganese and cobalt is not uniform, the influence of strain/crack of the composite oxide during the cyclic charge and discharge of the lithium ion secondary battery becomes large when the lithium ion secondary battery is applied. Since the metal composition is not uniform, the stress applied to the inside of the particle during expansion and contraction generates strain, and cracks are more likely to be generated in the composite oxide. Thus, high nickel ternary materials (e.g., LiNi)0.8Mn0.1Co0.1O2) Ternary materials with a uniform ratio of Ni, Mn and Co (e.g., LiNi)0.3Mn0.3Co0.3O2) The long-term cycle characteristics become remarkably degraded. However, this example provides a single-crystal high-nickel ternary cathode material, even if Li is used1.08Ni0.8Mn0.1Co0.1O2In such a case, when the composite oxide having a non-uniform metal composition is applied to a lithium ion secondary battery, the cycle characteristics of the lithium ion secondary battery are unexpectedly improved. Thus, for LiaNixCoyMnzO2Satisfies the following conditions: a is more than or equal to 1.05 and less than or equal to 1.08, and x is more than or equal to 0.85 and less than or equal to 0.88. 0.10. ltoreq. y.ltoreq.0.14, and z 1-x-y are preferable because the effects of the present invention can be remarkably obtained.
Example 4
This example provides a method for preparing the single-crystal high-nickel ternary cathode material provided in example 3, including the following steps:
s1 ball milling NiO, MnO and Co3O4Preparing a single-phase rock salt ternary precursor by using powder, wherein the submicron single-phase rock salt ternary precursor is a solid solution;
and S2, calcining the single-phase rock salt ternary precursor in mixed molten salt at high temperature, wherein the mixed molten salt comprises a Li compound and an inorganic salt, the molar ratio of the inorganic salt to the Li compound is 1-2:8, and the molar ratio of the Li compound to the single-phase rock salt ternary precursor is more than 2.
Wherein the Li compound is one or a mixture of more of lithium hydroxide or hydrate thereof, lithium peroxide, lithium nitrate and lithium carbonate.
Wherein the high-temperature calcination comprises primary high-temperature calcination and secondary high-temperature calcination, the time of the primary high-temperature calcination is 5-10h, and the temperature of the primary high-temperature calcination is 380-450 ℃; directly raising the temperature after the primary high-temperature calcination for secondary high-temperature calcination, wherein the time of the secondary high-temperature calcination is 12-18 h, and the temperature of the secondary high-temperature calcination is 950-980 ℃. And after the secondary high-temperature calcination, naturally cooling to room temperature, washing and drying to obtain the single-crystal high-nickel ternary cathode material provided by the embodiment 3.
The single crystal type high nickel ternary cathode material can be efficiently obtained through 2 stages of high-temperature calcination. The temperature and time at the time of the primary high-temperature calcination (precalcination) and the secondary high-temperature calcination (formal calcination) are particularly important as factors for controlling the primary particle size distribution of the single-crystal high-nickel ternary positive electrode material to be produced, and the primary particle size distribution of the single-crystal high-nickel ternary positive electrode material can be controlled by adjusting the calcination temperature and the calcination time based on the following tendency. That is, when the high-temperature calcination time is prolonged, the values of D90 and D50 increase, and the value of D10 decreases; when the firing temperature was increased, the values of D10 and D50 increased, and the value of D90 decreased. In this example, the temperature rise rate of the high-temperature calcination was 1 ℃ to 20 ℃/min. In addition, the high-temperature calcination may be performed in an oxygen atmosphere.
The existing high-nickel ternary cathode material has Li between oxygen layers+Layer, Ni3+Layered rock salt structure of the layer, Ni3+Is easy to be reduced into Ni2+And due to Ni2+Ionic radius of (2) and Li+The ionic radii of the Li are approximately equal, and the Li easily generated by the existing method for synthesizing the high-nickel ternary cathode material+Mixing Ni into the defective portion2+If in Li+Site mixing of Ni2+An electrochemically inert structure is locally formed and Li is hindered+This causes a decrease in charge/discharge capacity of the battery and a decrease in durability. The single-crystal high-nickel ternary cathode material prepared by the preparation method provided by the invention has less defects in crystals, and can inhibit the reduction of the charge and discharge capacity and the reduction of the durability of a battery.
The lithium ion secondary battery using the single-crystal high-nickel ternary positive electrode material prepared in this example can suppress deterioration of the electrode due to non-uniformity of voltage in the electrode plane, and improve cycle characteristics.
Example 5
The present embodiment provides a lithium ion secondary battery including a positive electrode, a negative electrode, and a separator. The positive electrode comprises a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer comprises the following components in percentage by mass: 90% single crystal type high nickel ternary anode material Li1.05Ni0.88Co0.1Mn0.02O25% of carbon black (conductive aid), 5% of polyvinylidene fluoride (binder). The negative electrode comprises a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer comprises the following components in percentage by mass: 95% of artificial graphite, 2% of carbon black (conductive aid), and 3% of ammonium salt of carboxymethyl cellulose (binder). The positive electrode, the diaphragm and the negative electrode are stacked and placed in a bag made of an aluminum laminated sheet as an outer shell, and an electrolyte is injected. The electrolyte is prepared as follows: make 1.0M LiPF6Dissolving in mixed solvent of ethylene carbonate and diethyl carbonate (EC and DEC in a volume ratio of 3: 7), and adding vinylene carbonate asAnd the weight of the additive and the vinylene carbonate is 1% of the weight of the electrolyte.
Example 6
The present embodiment provides a lithium ion secondary battery, which is different from the lithium ion secondary battery provided in embodiment 5 only in that: the chemical formula of the single crystal type high nickel ternary anode material in the anode active material layer is Li1.08Ni0.85Co0.14Mn0.01O2。
Example 7
The present embodiment provides a lithium ion secondary battery, which is different from the lithium ion secondary battery provided in embodiment 5 only in that: the chemical formula of the single crystal type high nickel ternary anode material in the anode active material layer is Li1.06Ni0.86Co0.12Mn0.02O2Satisfies the following conditions: a is more than or equal to 1.05 and less than or equal to 1.08, x is more than or equal to 0.85 and less than or equal to 0.88, and y is more than or equal to 0.10 and less than or equal to 0.14.
Example 8
The present embodiment provides a lithium ion secondary battery, which is different from the lithium ion secondary battery provided in embodiment 5 only in that: the chemical formula of the single crystal type high nickel ternary anode material in the anode active material layer is Li1.07Ni0.87Co0.11Mn0.02O2Satisfies the following conditions: a is more than or equal to 1.05 and less than or equal to 1.08, x is more than or equal to 0.85 and less than or equal to 0.88, and y is more than or equal to 0.10 and less than or equal to 0.14.
The single crystal type high nickel ternary positive electrode materials described in examples 5-8 were all prepared using the method provided in example 4.
Comparative example 1
This example provides a lithium ion secondary battery that differs from the lithium ion secondary battery provided in example 5 only in that the positive electrode active material layer is composed of the following components in mass percent: 90% of the existing high-nickel ternary material LiNi0.8Mn0.1Co0.1O25% of carbon black (conductive aid), 5% of polyvinylidene fluoride (binder).
Comparative example 2
This example provides a lithium ion secondary battery, which is different from the lithium ion secondary battery provided in example 5 only in that the positive electrode active material layer is composed of the following massThe components in percentage by weight are as follows: 90% of the existing high-nickel ternary material LiNi0.6Mn0.2Co0.2O25% of carbon black (conductive aid), 5% of polyvinylidene fluoride (binder).
The lithium ion secondary batteries provided in examples 5 to 8 and comparative examples 1 to 2 were each subjected to the following tests:
1. determination of the rated capacity
The measurement was carried out by the following steps 1 to 5 at a temperature of 25 ℃ and a voltage of 3.0V to 4.15V.
Step 1: after reaching 4.15V by constant current charging at 0.2C, the cell was stopped for 5 minutes.
Step 2: after the step 1, the charge was carried out for 1.5 hours by constant voltage charge and the operation was stopped for 5 minutes.
And step 3: after reaching 3.0V by constant current discharge at 0.2C, the discharge was performed for 2 hours by constant voltage discharge and then stopped for 10 seconds.
And 4, step 4: after 4.1V was reached by constant current charging at 0.2C, charging was carried out for 2.5 hours by constant voltage charging, and then the operation was stopped for 10 seconds.
And 5: after reaching 3.0V by constant current discharge at 0.2C, the discharge was performed for 2 hours by constant voltage discharge and then stopped for 10 seconds.
Rated capacity: the discharge capacity (CCCV discharge capacity) in the discharge from the constant-current discharge to the constant-voltage discharge in step 5 was taken as the rated capacity.
2. Charge and discharge cycle test
A charge-discharge cycle test was carried out in a thermostatic bath at 25 ℃ at a current of 1.5C, and the capacity retention rate after 300 cycles was calculated.
The test results are shown in table 1.
TABLE 1
| Rated capacity (Ah) | Capacity retention rate (%) | |
| Comparative example 1 | 4.2 | 12 |
| Comparative example 2 | 4.1 | 28 |
| Example 5 | 4.8 | 68 |
| Example 6 | 4.5 | 70 |
| Example 7 | 4.4 | 66 |
| Example 8 | 4.7 | 75 |
As is clear from the results shown in table 1, the lithium ion secondary battery using the single crystal type high nickel ternary positive electrode material provided by the present invention achieves a high capacity retention rate (improved cycle durability) as compared to the conventional high nickel ternary positive electrode material.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A ternary positive electrode material characterized in that: the ternary anode material is a single-crystal high-nickel ternary anode material, and the chemical formula of the single-crystal high-nickel ternary anode material is LiaNixCoyMnzO2Wherein a is more than or equal to 1.06 and less than or equal to 1.10, x is more than or equal to 0.8 and less than or equal to 0.9, y is more than or equal to 0.01 and less than or equal to 0.15, and z is 1-x-y; the single-crystal high-nickel ternary cathode material simultaneously meets the following requirements: the particle size distribution reaches 10%, the corresponding primary particle size D10 is not less than 4.1 μm, the average primary particle size D50 is not less than 9.5 μm, and the cumulative particle size distribution reaches 90%, the corresponding primary particle size D90 is not less than 17.5 um.
2. The ternary positive electrode material according to claim 1, characterized in that: the chemical formula of the single crystal type high-nickel ternary cathode material is LiaNixCoyMnzO2Wherein a is more than or equal to 1.05 and less than or equal to 1.08, x is more than or equal to 0.85 and less than or equal to 0.88, y is more than or equal to 0.10 and less than or equal to 0.14, and z is 1-x-y.
3. A method for preparing the ternary positive electrode material according to claim 1 or 2, comprising the steps of: by ball milling NiO, MnO and Co3O4Preparing a single-phase rock salt ternary precursor by using powder, wherein the submicron single-phase rock salt ternary precursor is a solid solution; and calcining the single-phase rock salt ternary precursor at high temperature in mixed molten salt, wherein the mixed molten salt comprises a Li compound and inorganic salt.
4. The method of claim 3, wherein: the molar ratio of the inorganic salt to the Li compound is 1-2:8, and the molar ratio of the Li compound to the single-phase rock salt ternary precursor is more than 2.
5. The method of claim 4, wherein: the Li compound is LiOH, and the inorganic salt is Na2SO4。
6. The method of claim 4, wherein: the high-temperature calcination comprises primary high-temperature calcination and secondary high-temperature calcination, and the temperature is directly increased after the primary high-temperature calcination for the secondary high-temperature calcination.
7. The method of claim 6, wherein: the time of the primary high-temperature calcination is 5-10h, and the temperature of the primary high-temperature calcination is 380-450 ℃.
8. The method of claim 7, wherein: the time of the secondary high-temperature calcination is 12h-18h, and the temperature of the secondary high-temperature calcination is 950 ℃ to 980 ℃.
9. A lithium battery having a positive electrode including a positive electrode current collector and a positive electrode active material layer formed on a surface of the positive electrode current collector, characterized in that: the positive electrode active material layer contains the ternary positive electrode material according to claim 1 or 2.
10. A lithium battery as claimed in claim 9, characterized in that: the lithium battery is an all-solid-state battery.
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