Ternary material and preparation method therefor, lithium-ion battery and electric device

Abstract

A ternary material, having a chemical formula of LiNi1-x-yCoxMnyMaO2, wherein 0<x≤0.1, 0<y≤0.3, 0<a≤0.05, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, W, Al and B. The ternary material comprises single-crystal particles. An X-ray diffraction pattern of the ternary material has a (108) diffraction peak at a diffraction angle 2θ of 64±0.5° and a (110) diffraction peak at a diffraction angle 2θ of 65±0.5°, which satisfy the following relational expression: (a).

Description

A ternary material and preparation method thereof, lithium-ion battery and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 29, 2023, with application number 202311863040.4 and invention name “A ternary material and its preparation method, positive electrode sheet, lithium-ion battery and electrical equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure belongs to the field of energy storage technology, and specifically relates to a ternary material and a preparation method thereof, a lithium-ion battery, and electrical equipment. Background Art

[0003] Lithium-ion battery cathode materials are a crucial component of lithium-ion batteries and a key factor influencing their performance. Lithium nickel cobalt manganese oxide (ternary material) combines the advantages of lithium manganese oxide, lithium cobalt oxide, and lithium nickel oxide, offering high specific capacity and excellent discharge rate, making it the primary cathode material for lithium-ion batteries.

[0004] The main development trend of ternary materials is single crystalization. Single crystal particles can reduce grain boundary cracking during the ternary material cycle and improve the cycle life of ternary materials. However, the preparation of single crystal materials requires higher sintering temperatures. High temperatures easily cause lithium and nickel to mix. The higher the nickel content, the more severe the mixing phenomenon, which in turn affects the orderliness of the ternary material structure and leads to poor cycle performance of ternary lithium batteries. Summary of the Invention

[0005] The first aspect of the present disclosure provides a ternary material, wherein the chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, wherein 0<x≤0.1, 0<y≤0.3, 0<a≤0.05, M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B; the ternary material comprises single crystal particles; in the X-ray diffraction spectrum of the ternary material, there is a (108) diffraction peak at a diffraction angle 2θ of (64±0.5)° and a (110) diffraction peak at a diffraction angle 2θ of (65±0.5)°; the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: Wherein, FWHM(108) is the half-maximum width of the (108) diffraction peak; FWHM(110) is the half-maximum width of the (110) diffraction peak.

[0006] In a second aspect, the present disclosure provides a method for preparing a ternary material, comprising the following steps: 1) mixing a first lithium source with a transition metal precursor to obtain a first mixture, and adding a gelling agent and a first dopant to the first mixture to obtain gel particles; wherein the transition metal precursor includes nickel, cobalt, and manganese elements; the molar ratio of the nickel, cobalt, and manganese elements is (1-xy): x:y, 0<x≤0.1, 0<y≤0.3; the molar ratio of the lithium element in the first lithium source to the sum of the nickel, cobalt, and manganese elements in the precursor is (0.3-0.9):1; 2) mixing the gel particles with a second lithium source to obtain a second mixture, and sintering the second mixture for the first time in an oxygen-containing atmosphere to obtain a single-sintering product. material; wherein the molar ratio of the lithium element in the second lithium source to the sum of the nickel, cobalt and manganese elements in the precursor is (0.15-0.75):1; the first lithium source and the second lithium source may be the same or different; 3) mixing the primary sintered product with an optional second dopant, and performing a second sintering in an oxygen-containing atmosphere to obtain the ternary material; wherein the first dopant and the second dopant include an M element, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B; the ratio of the sum of the molar amounts of the M element in the first dopant and the second dopant to the sum of the molar amounts of the nickel, cobalt and manganese elements in the precursor is a:1, 0<a≤0.05.

[0007] In a third aspect, the present disclosure provides a positive electrode sheet comprising the above-mentioned ternary material, or the ternary material obtained by the above-mentioned preparation method.

[0008] In a fourth aspect, the present disclosure provides a positive electrode sheet, wherein the positive electrode sheet comprises a ternary material, wherein the chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, wherein 0<x≤0.1, 0<y≤0.3, 0<a≤0.05, M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B; the ternary material comprises single crystal particles; in the X-ray diffraction spectrum of the positive electrode sheet, there is a (108) diffraction peak at a diffraction angle 2θ of (64±0.5)° and a (110) diffraction peak at a diffraction angle 2θ of (65±0.5)°; the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: Wherein, FWHM(108) is the half-maximum width of the (108) diffraction peak; FWHM(110) is the half-maximum width of the (110) diffraction peak.

[0009] In a fifth aspect, the present disclosure provides a lithium-ion battery comprising the above-mentioned positive electrode sheet.

[0010] In a sixth aspect, the present disclosure provides an electrical device comprising the above-mentioned lithium-ion battery.

[0011] The ternary material disclosed in the present invention can ensure the stability of the high-nickel ternary material layer structure and the orderliness of the arrangement of the transition metal elements and lithium between the layers, so that the ternary material has a higher specific capacity while taking into account a high cycle life. Compared with the prior art, the preparation method of the ternary material has the following effects: First, a gelling agent pretreatment process is adopted to make the lithium element close to the lithium site after sintering in advance and form a van der Waals force, so as to ensure that the lithium and nickel, cobalt and manganese are more regularly combined in the lattice during the subsequent sintering process, the lattice crystallinity is higher, the crystal form is more complete, the internal stress is small, and it is not easy to produce internal lattice dislocations; second, the step-by-step lithium mixing and / or doping process makes the lithium ions and / or doping elements more evenly mixed with the transition metal precursor, and the arrangement is more orderly after being embedded in the ternary material lattice, thereby making the crystallinity inside and outside the ternary material consistent, which is more conducive to the generation of single crystal materials; third, the step-by-step sintering process can adjust the sintering temperature multiple times to balance the negative impact of continuous high temperature on the lithium-nickel mixing of single crystal materials.

[0012] Compared with the existing technology, the preparation method of ternary materials has the following effects: first, a gelling agent pretreatment process is adopted to make the lithium element approach the lithium site after sintering in advance and form van der Waals force, thereby ensuring that lithium and nickel, cobalt and manganese are more regularly combined in the lattice during the subsequent sintering process, the lattice crystallinity is higher, the crystal form is more complete, the internal stress is small, and it is not easy to produce internal lattice dislocations; second, a step-by-step lithium mixing and / or doping process is used to make the lithium ions and / or doping elements more evenly mixed with the transition metal precursor, and the arrangement is more orderly after being embedded in the ternary material lattice, thereby making the crystallinity inside and outside the ternary material consistent, which is more conducive to the generation of single crystal materials; third, the step-by-step sintering process can adjust the sintering temperature multiple times to balance the negative impact of continuous high temperature on the lithium-nickel mixing of single crystal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are used to provide further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure, but do not constitute a limitation of the present disclosure.

[0014] FIG1 is a SEM image of the transition metal precursor in Example 1 of the present disclosure at a magnification of 10,000 times;

[0015] FIG2 is a SEM image of the transition metal precursor in Example 1 of the present disclosure magnified 50,000 times;

[0016] FIG3 is a SEM image of the ternary material prepared in Example 1 of the present disclosure at a magnification of 10,000 times. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects solved by the present disclosure more clearly understood, the present disclosure is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not intended to limit the present disclosure.

[0018] Lithium nickel cobalt manganese oxide (ternary material) combines the advantages of lithium manganese oxide, lithium cobalt oxide, and lithium nickel oxide, and is widely used as a ternary material in lithium-ion batteries. In the crystal structure of the ternary material, transition metal ions and lithium ions alternately occupy the octahedral voids and are arranged in layers. This atomic arrangement gives the ternary material excellent electrochemical properties. Single crystalization is currently one of the main directions of ternary material development. Single crystal particles can reduce grain boundary cracking during the material cycle and improve the cycle life of the ternary material. However, the preparation of single crystals requires a higher sintering temperature. High temperature can easily cause the mixing of lithium and nickel, thereby degrading the specific capacity and cycle life of the material.

[0019] The first embodiment of the present disclosure provides a ternary material, wherein the chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, wherein 0<x≤0.1, 0<y≤0.3, 0<a≤0.05, M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B; the ternary material comprises single crystal particles; in the X-ray diffraction spectrum of the ternary material, there is a (108) diffraction peak at a diffraction angle 2θ of (64±0.5)° and a (110) diffraction peak at a diffraction angle 2θ of (65±0.5)°; the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: Wherein, FWHM(108) is the half-maximum width of the (108) diffraction peak; FWHM(110) is the half-maximum width of the (110) diffraction peak.

[0020] Ternary materials belong to the hexagonal crystal system, in which the (110) crystal plane is related to the a and b axes, while the (108) crystal plane is more strongly related to the c axis. The combination of the (110) crystal plane and the (108) crystal plane can reflect the characteristics of the a, b, and c axes in the unit cell of the ternary material, and can be used to evaluate the crystal structure of the ternary material. It can roughly determine the order of the layered structure of the ternary material and evaluate the rationality of the atomic arrangement between each layer. The two diffraction peaks of the (108) and (110) crystal planes in the XRD spectrum of the ternary material show obvious split peaks, which is a sign that the crystal structure of the ternary material has reached the appropriate range. At this time, a regular lamellar structure composed of alternating transition metals and lithium has been formed in the ternary material.

[0021] After extensive experimental research, the inventors of the present disclosure have found that when the X-ray diffraction spectrum of the single crystal ternary material has a (108) diffraction peak at a diffraction angle 2θ of (64±0.5)° and a (110) diffraction peak at a diffraction angle 2θ of (65±0.5)°, and the (108) diffraction peak and the (110) diffraction peak satisfy the relationship: When the transition metal and lithium in the ternary material are alternately arranged more regularly, there is less mixing of lithium and nickel, and the specific capacity is higher; and the layer structure formed by the alternation of transition metal and lithium is more stable, which can ensure that the ternary material has a higher cycle life.

[0022] In the present disclosure, single crystal particles are relative to polycrystalline particles; wherein, from the perspective of morphology, single crystal particles are single dispersed or quasi-single dispersed particles; polycrystalline particles are secondary particles formed by the agglomeration of multiple primary particles.

[0023] Specifically, in the relationship, 2θ(110) refers to the specific position of the (110) diffraction peak in the X-ray diffraction spectrum actually obtained when performing XRD testing on the ternary material. Similarly, 2θ(108) refers to the specific position of the (108) diffraction peak in the X-ray diffraction spectrum actually obtained when performing XRD testing on the powder of the ternary material.

[0024] In some preferred embodiments of the present disclosure, the chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, where 0<x≤0.1, 0<y≤0.1, 0<a≤0.02.

[0025] As the Ni content in the ternary material increases, the specific capacity of the ternary material increases; however, as the Ni content increases, the risk of lithium-nickel mixing also increases, resulting in a reduced cycle life. Therefore, when the above relationship is met, the stability of the high-nickel ternary material layer structure and the orderly arrangement of the transition metal elements and lithium between the layers can be guaranteed, allowing the ternary material to have a higher specific capacity while also taking into account a long cycle life.

[0026] In some preferred embodiments of the present disclosure, the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship:

[0027] In some preferred embodiments of the present disclosure, the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: When the relationship is within the above preferred range, the layered structure of the ternary material is more ordered and the atomic arrangement between the transition metal layers is more stable, so that the ternary material has a higher specific capacity while also taking into account a long cycle life.

[0028] In some preferred embodiments of the present disclosure, in the X-ray diffraction spectrum of the ternary material, the half maximum width FWHM (108) of the (108) diffraction peak ranges from 0.1 to 0.15.

[0029] Specifically, the half-maximum width (FWHM) (108) of the (108) diffraction peak refers to the value of the peak width of the (108) diffraction peak at the half-maximum height of the (108) diffraction peak, which is parallel to the diffraction angle 2θ axis in the X-ray diffraction spectrum. The FWHM (108) range is between 0.1 and 0.15. The prepared ternary material does not contain quasicrystals, has good single crystal properties, has smooth lithium ion insertion and extraction channels, and has good rate performance.

[0030] In the present disclosure, in some preferred embodiments, in the X-ray diffraction spectrum of the ternary material, the half-maximum width FWHM (110) of the (110) diffraction peak at a diffraction angle 2θ of (65±0.5)° is in the range of 0.1 to 0.15. Specifically, the half-maximum width FWHM (110) of the (110) diffraction peak refers to the value of the peak width of the (110) diffraction peak at the half-maximum height position of the (110) diffraction peak, which is parallel to the diffraction angle 2θ axis in the X-ray diffraction spectrum. The FWHM (110) range is between 0.1 and 0.15, and the prepared ternary material does not contain quasicrystals, has good single crystal characteristics, unobstructed lithium ion insertion and extraction channels, and good rate performance.

[0031] In some preferred embodiments of the present disclosure, the ternary material has an α-NaFeO2 layered structure.

[0032] It is understood that the X-ray diffraction spectrum of the ternary material in the present disclosure can be obtained by scanning with a copper target X-ray generator at 3° to 90° at a scanning rate of 2 to 5° / min.

[0033] In some preferred embodiments of the present disclosure, the particle size (D50) of the ternary material is 2 μm-6 μm. Within this particle size range, the ternary material can be guaranteed to have better mechanical strength and compaction density.

[0034] According to a second aspect of the present disclosure, a method for preparing a ternary material is provided, comprising the following steps: 1) mixing a first lithium source with a transition metal precursor to obtain a first mixture, and adding a gelling agent and a first dopant to the first mixture to obtain gel particles; wherein the transition metal precursor includes nickel, cobalt, and manganese elements; the molar ratio of the nickel, cobalt, and manganese elements is (1-xy): x:y, 0<x≤0.1, 0<y≤0.3; the molar ratio of the lithium element in the first lithium source to the total of the nickel, cobalt, and manganese elements in the precursor is (0.3-0.9):1; 2) mixing the gel particles with a second lithium source to obtain a second mixture, and sintering the second mixture for the first time in an oxygen-containing atmosphere to obtain a single-sintering product. material; wherein the molar ratio of the lithium element in the second lithium source to the sum of the nickel, cobalt and manganese elements in the precursor is (0.15-0.75):1; the first lithium source and the second lithium source may be the same or different; 3) mixing the primary sintered product with an optional second dopant, and performing a second sintering in an oxygen-containing atmosphere to obtain the ternary material; wherein the first dopant and the second dopant include an M element, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B; the ratio of the sum of the molar amounts of the M element in the first dopant and the second dopant to the sum of the molar amounts of the nickel, cobalt and manganese elements in the precursor is a:1, 0<a≤0.05.

[0035] Compared with the prior art, the preparation method of the ternary material provided by the present invention has the following effects: first, a gelling agent pretreatment process is adopted to make the lithium element approach the lithium site after sintering in advance and form van der Waals force, thereby ensuring that lithium and nickel, cobalt and manganese are more regularly combined in the lattice during the subsequent sintering process, the lattice crystallinity is higher, the crystal form is more complete, the internal stress is small, and it is not easy to produce internal lattice dislocations; second, a step-by-step lithium mixing and / or doping process is used to make the lithium ions and / or doping elements more evenly mixed with the transition metal precursor, and the arrangement is more orderly after being embedded in the ternary material lattice, thereby making the crystallinity inside and outside the ternary material consistent, which is more conducive to the generation of single crystal materials; third, the step-by-step sintering process can adjust the sintering temperature multiple times to balance the negative impact of continuous high temperature on the lithium-nickel mixing of single crystal materials.

[0036] Specifically, in step 1), the order of adding the gelling agent and the dopant is not limited; the gelling agent can be added first and mixed with the first mixture before the dopant is added; the dopant can be added first and mixed with the first mixture before the gelling agent is added; and the gelling agent and the dopant can be added simultaneously and mixed with the first product.

[0037] Specifically, the transition metal precursor is suitable for preparing ternary single crystal particles.

[0038] In some preferred embodiments of the present disclosure, the transition metal precursor has a D50 of approximately 2 μm to 6 μm, with a morphology of small, approximately round agglomerates. The primary particles are relatively coarse, and subsequent sintering and pulverization will break up the agglomerates, so the appearance of the single crystal precursor is not inherited by the ternary single crystal particles. The pulverization method is preferably airflow pulverization.

[0039] In some preferred embodiments of the present disclosure, the nickel-cobalt-manganese precursor includes at least one of a hydroxide precursor or a carbonate precursor.

[0040] In some preferred embodiments of the present disclosure, the first lithium source and the second lithium source are each independently a lithium-containing compound. Preferably, the lithium-containing compound includes one or more of lithium hydroxide, lithium nitrate, lithium carbonate, lithium acetate, lithium chloride, lithium fluoride, and lithium iodide.

[0041] In the present disclosure, in some preferred embodiments, the first dopant and the second dopant may be the same or different. The above dopants are compounds containing doping elements. The doping elements include M elements, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B. Optionally, the compound containing doping elements includes at least one of zinc hydroxide, magnesium hydroxide, molybdenum hydroxide, vanadium hydroxide, germanium hydroxide, aluminum hydroxide, titanium dioxide powder, zirconium oxide powder, tantalum pentoxide, yttrium oxide, boric acid and tungstic acid. The above doping elements are similar to the radius of transition metal ions and have a strong binding energy with oxygen, which makes the crystal structure of the obtained ternary material more stable, which is beneficial to reducing the ion diffusion resistance of the single crystal ternary material.

[0042] In some preferred embodiments of the present disclosure, the molar ratio of the lithium element in the lithium compound to the M element in the dopant is 1:(0.001-0.05); wherein the dopant includes a first dopant and a second dopant. By controlling the molar ratio of lithium to the doping element within the above range, the effectiveness of elemental doping can be improved. Appropriate elemental doping can reduce the degree of nickel ion mixing in the material, improve the stability of the crystal surface structure, effectively suppress the lattice distortion generated by the ternary material during the charge and discharge process, reduce the number of times lithium ions pass through the grain boundaries during the deintercalation process, and make lithium ions deintercalate more rapidly during the cycle, thereby improving the structural stability and rate performance of the material.

[0043] In some preferred embodiments of the present disclosure, the gelling agent comprises a solvent, a complexing agent, and a polymer monomer; wherein the mass percentage of the solvent in the gelling agent is 10wt%-50wt%, and the solvent comprises at least one of anhydrous ethanol or deionized water. When the mass percentage of the solvent in the gelling agent is within the above range, it can effectively disperse the lithium source, uniformly dispersing the lithium ions on the surface of the transition metal precursor, facilitating lithiation.

[0044] In some preferred embodiments of the present disclosure, the mass percentage of the complexing agent in the gelling agent is 0.2 wt% to 2 wt%; the complexing agent includes sodium dodecyl sulfate (SDS). The complexing agent facilitates the bonding of the gelling agent and the lithium source, and the mass percentage of the complexing agent within the above range facilitates the dispersion of the lithium source in the gelling agent, facilitating the formation of a more stable ternary material.

[0045] In the present disclosure, in some preferred embodiments, the volume ratio of the polymer monomer to the solvent is (0.1-0.4):1; the polymer monomer includes at least one of methyl methacrylate, styrene or acrylonitrile; preferably methyl methacrylate. The polymer monomer is a precursor for forming a gel. By controlling the volume ratio of the polymer monomer to the solvent within the above range, it is beneficial to form a gel with better coating performance, which is convenient for improving the crystallinity after lithiation. Among them, the methyl methacrylate will polymerize into polymethyl methacrylate during the mixing process, which has higher dispersibility for lithium sources and better bonding with the surface of the metal precursor. At the same time, the residual carbon content of the finished product after sintering of polymethyl methacrylate is in the range of 0.1%wt to 3%wt. The residual carbon rate in this range is conducive to further improving the rate performance.

[0046] In some preferred embodiments of the present disclosure, in the process of adding the gelling agent and the optional dopant to the first mixture to obtain gel particles, appropriate heating treatment can be performed at a heating temperature of 40°C to 80°C, which is conducive to the polymerization reaction.

[0047] In some preferred embodiments of the present disclosure, the first sintering includes: a first sintering temperature of 600° C. to 950° C., a first sintering time of 8 h to 24 h, and a first cooling after the first sintering.

[0048] In the present disclosure, some preferred embodiments, the second sintering includes: after the first cooling is completed, a second sintering is performed in a pure oxygen atmosphere environment, the second sintering temperature is 300℃~750℃, the second sintering time is 3h~24h, and a second cooling is performed after the second sintering is completed. The use of two sinterings makes the ternary material have a high degree of crystallinity, and the use of two cooling methods to control the grain size of the intermediate product so that the grains of the ternary material are quickly stabilized within a suitable size range, which is beneficial to improving the compaction density of the ternary material, while also avoiding the generation of other impurities and improving the orderliness of the layered structure of the ternary material. The two-sintering cooling method saves the cooling time of the sintering equipment, shortens the process time, and is also beneficial to obtaining a ternary material with a highly ordered layered structure, so that the ternary material has a higher specific capacity.

[0049] In some embodiments, the first sintering also includes: a heating rate of 1°C / min-8°C / min during the first sintering, a first sintering time (or first sintering time) of 8h~24h under the conditions of a first sintering temperature of 600°C~950°C, a first cooling after the first sintering is completed, the first cooling temperature is 20-30°C, and the cooling method adopts sudden cooling, and the first sintering product after sintering is directly transferred to room temperature.

[0050] The first sintering of the transition metal precursor helps form a ternary material with good crystallinity. It also carbonizes the polymer coating of the transition metal precursor, increasing the material's true density and adjusting its specific surface area. The first cooling operation, performed after the first sintering, aims to control the grain size of the intermediate product, quickly stabilizing the material's grain size. This ensures rapid crystallization of the ternary material, avoids the formation of other impurities, and improves the orderliness of the ternary material's layered structure.

[0051] In some embodiments, the second sintering includes: a heating rate of 1°C / min-8°C / min during the second sintering, a second sintering temperature of 300°C~750°C, a second sintering time of 3h~24h, and a second cooling after the second sintering. The second cooling temperature is 20-30°C, and the cooling method adopts sudden cooling, and the second sintering product after sintering is directly transferred to room temperature.

[0052] Specifically, the pure oxygen atmosphere environment refers to a space filled with pure oxygen, and the second sintering is carried out in a space filled with pure oxygen. The first sintering and the second sintering have the same function, which is to help form a ternary material with better crystallinity and improve the density of the ternary material. The first cooling and the second cooling also have the same function, which is to control the grain size of the intermediate product, so that the grains of the ternary material can quickly stabilize at a fixed size, increase the compaction density of the ternary material when preparing the electrode, and at the same time, ensure the rapid crystallization of the ternary material, avoid the generation of other miscellaneous products, and improve the orderliness of the layered structure of the ternary material. It is understandable that the equipment used for the first sintering and the second sintering includes one of a tube furnace, a box furnace, a fluidized bed, a rotary kiln, a microwave oven, and a tunnel furnace.

[0053] In some preferred embodiments of the present disclosure, the method for preparing the ternary material further includes performing a third sintering after cooling from the second sintering, wherein the third sintering temperature is 300-500°C and the sintering time is 3-8 hours. During the third sintering, a lithium source and / or dopant may be optionally added. The third sintering is primarily intended to form a more stable ternary material with higher crystallinity.

[0054] In a third aspect of the present disclosure, a positive electrode sheet is provided, comprising the ternary material provided in the first aspect, or the ternary material prepared by the preparation method of the ternary material provided in the second aspect.

[0055] The positive electrode sheet provided by the present disclosure contains the above-mentioned ternary material and has a high specific capacity and cycle life.

[0056] The positive electrode sheet is prepared by using the above-mentioned ternary material and applied to the battery, and the battery has a higher energy density and cycle life.

[0057] In some preferred embodiments of the present disclosure, the compaction density of the positive electrode sheet is 3.2 g / cm 3 ~3.5g / cm 3 .

[0058] The positive electrode sheet prepared using the ternary material prepared in the present disclosure has a relatively complete layered structure and a high compaction density. When used in batteries, it can improve the energy density and cycle life of the battery.

[0059] In a fourth aspect of the present disclosure, a positive electrode sheet is provided, comprising a ternary material, wherein the chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, wherein 0<x≤0.1, 0<y≤0.3, 0<a≤0.05, M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B; the ternary material comprises single crystal particles; in the X-ray diffraction spectrum of the positive electrode sheet, there is a (108) diffraction peak at a diffraction angle 2θ of (64±0.5)° and a (110) diffraction peak at a diffraction angle 2θ of (65±0.5)°; the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: Wherein, FWHM(108) is the half-maximum width of the (108) diffraction peak; FWHM(110) is the half-maximum width of the (110) diffraction peak.

[0060] In a fifth aspect, the present disclosure provides a lithium-ion battery comprising the above-mentioned positive electrode sheet. The lithium-ion battery using the present disclosure has a high energy density and a high cycle life.

[0061] The lithium-ion battery further comprises a negative electrode sheet, a diaphragm and an electrolyte. The negative electrode sheet comprises a current collector and a negative electrode active material layer coated on at least one side of the current collector; the negative electrode active material layer comprises a negative electrode active material, a conductive agent and a binder.

[0062] The negative electrode active material includes a carbon-based material; the carbon-based material includes one or more of artificial graphite, natural graphite, hard carbon material or soft carbon material.

[0063] The negative electrode active material also includes one or more of silicon-based materials, tin-based materials, and lithium titanate materials. The silicon-based material can be elemental silicon, silicon oxide (SiO x , 0<x<2), silicon alloy or a combination of one or more. The tin-based material can be elemental tin, tin oxide (SnO x , 0<x≤2), a combination of one or more of tin alloys. The lithium titanate material can be Li4Ti5O 12 wait.

[0064] The binder can be a combination of one or more of styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyethylene acrylic acid (PEAA), sodium alginate, carboxymethyl chitosan, polyacrylonitrile (PAN) and polyvinyl alcohol (PVA).

[0065] The current collector can be any one of copper foil, carbon-coated copper foil, polymer-coated copper foil, carbon cloth, carbon nanotube film or carbon paper.

[0066] The diaphragm can be one of polyethylene, polypropylene, polyvinylidene fluoride, or a composite membrane of multiple materials.

[0067] The electrolyte is an organic solvent in which carrier ions are dissolved. The present disclosure does not limit the electrolyte and the electrolyte can be prepared according to the actual situation.

[0068] In a sixth aspect of the present disclosure, an electrical device is provided, comprising the above-mentioned lithium-ion battery.

[0069] The electric device prepared using the lithium-ion battery disclosed herein can have higher market competitiveness.

[0070] In some embodiments of the present disclosure, the above-mentioned electrical devices include but are not limited to mobile phones, laptops, tablet computers, smart watches and other wearable electronic devices, electronic cigarettes, new energy vehicles, electric assisted bicycles, etc.

[0071] The present disclosure is further described in detail below through examples.

[0072] Example 1

[0073] This embodiment is used to illustrate the ternary material disclosed in the present disclosure and its preparation method, which includes the following steps:

[0074] 1) Use Ni 0.92 Co 0.06 Mn 0.02 A hydroxide precursor is prepared, using LiOH as a lithium source, and first adding lithium hydroxide in a ratio of lithium: transition metal element = 0.4 and mixing to obtain a first mixture; titanium dioxide powder (calculated based on the molar content of titanium element to obtain 1250 ppm), zirconium oxide powder (calculated based on the molar content of zirconium element to obtain 2500 ppm), tantalum pentoxide (calculated based on the molar content of tantalum element to obtain 1000 ppm) and yttrium oxide powder (calculated based on the molar content of yttrium element to obtain a supplementary content of 1000 ppm) are further added to the first mixture, and high-speed mixing is performed for 8 hours; the mixture is then poured into a ball mill and ball-milled with anhydrous ethanol for 8 hours, and then 0.4 wt% sodium lauryl sulfate, 30 wt% H2O, and methyl methacrylate with a volume ratio of 0.25 to water are added to the mixture, and stirred for 1 hour to obtain a mixture of a gel-encapsulated precursor, a lithium salt, and a dopant, and the above mixture is heated to 80° C., kept warm for 1 hour, and gel particles are collected;

[0075] 2) The gel particles were then mixed again with LiOH at a ratio of lithium to transition metal element = 0.63 at high speed, and then sintered for the first time in an oxygen atmosphere at a heating rate of 5°C / min and a sintering temperature of 800°C for 18 hours, followed by crushing and sieving to obtain a first sintered product;

[0076] 3) The first sintered product was mixed with alumina powder (calculated based on the molar content of aluminum element to obtain 1500 ppm) and subjected to a second sintering at a heating rate of 5°C / min, a sintering temperature of 700°C, a sintering time of 10 h, and an oxygen atmosphere, and then crushed and sieved to obtain a second sintered product;

[0077] 4) The second sintered product was mixed with boric acid (calculated based on the molar content of boron element to obtain 1000 ppm) and tungstic acid powder (calculated based on the molar content of tungsten element to obtain 1000 ppm), sintered in an oxygen atmosphere at 300°C for 5 hours, and pulverized to obtain the final ternary material.

[0078] Among them, Ni 0.92 Co 0.06 Mn 0.02 The D50 of the hydroxide precursor is 4 μm, and its SEM images at different magnifications are shown in Figures 1 and 2. In the low-magnification SEM (Figure 1), Ni 0.92 Co 0.06 Mn 0.02 The hydroxide precursor is composed of secondary spherical particles accumulated from primary particles; in the high-magnification SEM (Figure 2), the primary particles are relatively coarse. The obtained ternary material product (LiNi 0.90 Co 0.05 Mn 0.05O2) has a D50 of 4 μm, and its SEM is shown in Figure 3. 0.92 Co 0.06 Mn 0.02 MO2 does not inherit Ni 0.92 Co 0.06 Mn 0.02 The hydroxide precursor morphology is not formed, but irregular primary particles are formed.

[0079] The finished ternary material was subjected to XRD testing using a copper target X-ray generator and scanning at a scanning rate of 3° / min from 10° to 80°.

[0080] Example 2

[0081] The difference between Example 2 and Example 1 is that titanium dioxide and tantalum pentoxide are not added during the sintering in step 1).

[0082] Example 3

[0083] The difference between Example 3 and Example 1 is that no aluminum oxide is added in step 2).

[0084] Example 4

[0085] The difference between Example 4 and Example 1 is that no tungstic acid is added in step 4).

[0086] Example 5

[0087] The difference between Example 5 and Example 1 is that tantalum pentoxide and yttrium oxide powder are not added in the sintering of step 1); aluminum oxide is not added in step 2); and step 4) is not performed.

[0088] Example 6

[0089] The difference between Example 6 and Example 1 is that Ni 0.89 Co 0.06 Mn 0.06 The precursor of the ratio was sintered at 770℃ for the first time for 16h and 620℃ for the second time for 8h.

[0090] Example 7

[0091] Example 7 differs from Example 1 in that, in step 1), lithium hydroxide is added at a ratio of lithium:transition metal element=0.9; and in step 2), lithium hydroxide is added at a ratio of lithium:transition metal element=0.15.

[0092] Example 8

[0093] Example 8 differs from Example 1 in that, in step 1), 2 wt % sodium dodecyl sulfate (SDS), 50 wt % H 2 O, and methyl methacrylate (MMA) in a volume ratio of 0.4 to water are added to the mixture.

[0094] Example 9

[0095] Example 9 differs from Example 1 in that, in step 1), 0.2 wt % sodium dodecyl sulfate (SDS), 10 wt % H 2 O, and methyl methacrylate (MMA) at a volume ratio of 0.1 to water are added to the mixture.

[0096] Example 10

[0097] Example 10 differs from Example 1 in that, in step 1), 0.8 wt % sodium dodecyl sulfate (SDS), 40 wt % H 2 O, and methyl methacrylate (MMA) in a volume ratio of 0.5 to water are added to the mixture.

[0098] Comparative Example 1

[0099] The difference between Comparative Example 1 and Example 1 is that the gel coating treatment in Example 1 was not performed.

[0100] Comparative Example 2

[0101] The difference between Comparative Example 2 and Example 1 is that the element doping and gel coating treatment in Example 1 are not performed, and the lithium source is not added in batches. In the first mixing process, lithium hydroxide is added at a ratio of lithium:transition metal element = 1.05.

[0102] Comparative Example 3

[0103] The difference between Comparative Example 3 and Example 6 is that the gel coating treatment in Example 6 was not performed, lithium was added in batches, and lithium hydroxide was added at a ratio of lithium:transition metal element=1.05.

[0104] Comparative Example 4

[0105] The difference between Comparative Example 4 and Example 1 is that Ni 0.74 Mn 0.26 The precursor has a first sintering temperature of 820°C for 14 hours and a second sintering temperature of 600°C for 8 hours. The lithium addition and doping treatment in Example 1 were not performed. Lithium hydroxide was added at a ratio of lithium to transition metal element of 1.05.

[0106] The specific data of FWHM(108), FWHM(110), 2θ(108), and 2θ(110) in the XRD spectra obtained after XRD testing of the ternary materials prepared in the above Examples 1-10 and Comparative Examples 1-4 are recorded in Table 1. The XRD half-peak width and peak position data are derived from the analysis of the XRD original test file by the processing software MDIJade 6. The specific data are shown in Table 1.

[0107] Table 1 Partial data of ternary materials of Examples 1-10 and Comparative Examples 1-4

[0108] The positive electrode sheet S containing the ternary materials of Examples 1, 7, Comparative Examples 1, and 4 was selected, and the specific data of FWHM(108), FWHM(110), 2θ(108), and 2θ(110) in the XRD spectrum obtained after the XRD test of the above positive electrode sheet were recorded in Table 2. The XRD half-peak width and peak position data were derived from the analysis of the XRD original test file by the processing software MDIJade 6. The specific data are shown in Table 2.

[0109] Table 2 Positive electrode part data table

[0110] Performance testing:

[0111] The ternary materials prepared in the above Examples 1-10 and Comparative Examples 1-4 were used to prepare positive electrode sheets and batteries, and the following tests were performed.

[0112] Specific capacity test: The above ternary materials were mixed with PVDF and SP in a ratio of 96:3:1 using NMP as solvent for 2 hours to form a stable and uniform positive electrode slurry. The positive electrode slurry was coated on aluminum foil using a coating machine, dried, and cold pressed to obtain a compaction density of 3.40g / cm 3 The positive electrode sheet was dried at 120°C for 24 hours. A lithium sheet was used as the negative electrode, a Cellgard 2300 porous membrane was used as the separator, and a 1 mol / L LiPF6 + DMC (volume ratio 1:1) mixed electrolyte was used as the electrolyte. A button cell 2032 was assembled and tested. Charge and discharge tests were performed at a 0.2C rate. The specific capacity of the third discharge test was taken as the specific capacity of the ternary material.

[0113] Battery preparation: The positive electrode sheet, negative electrode sheet and separator prepared above are made into bare cells according to conventional preparation processes, and the bare cells are dried, injected with electrolyte, and packaged to finally make batteries.

[0114] Among them, the negative electrode active material artificial graphite, conductive carbon black, thickener (CMC), and binder (SBR) are mixed in a ratio of 96:1:1:2, and the powder and deionized water are stirred into a negative electrode slurry using a homogenizer and evenly coated on a copper foil to obtain a negative electrode sheet.

[0115] Room temperature cycle performance test: The formed cells were subjected to a room temperature 25°C cycle test, with charge and discharge tests performed at 0.5C / 0.5C, and the discharge capacity retention of the battery after 500 cycles was recorded.

[0116] Direct current internal resistance (DCIR) test: The formed cells were subjected to a high temperature 45°C cycle test, with charge and discharge tests performed at 1C / 1C, and the DCIR retention of the battery was recorded after 500 cycles.

[0117] Table 2 Performance data of Examples 1-10 and Comparative Examples 1-4

[0118] It can be seen from the data in Table 3 that the ternary material provided by the embodiment of the present disclosure meets the crystal structure characteristics required by the present disclosure, and the discharge capacity, cycle performance and DCIR of the battery are improved relative to the control example.

[0119] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A ternary material, wherein, The chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, where 0 < x ≤ 0.1, 0 < y ≤ 0.3, 0 < a ≤ 0.05, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W, and B; The ternary material includes single crystal particles; In the X-ray diffraction spectrum of the ternary material, there are (108) diffraction peaks with a diffraction angle 2θ at (64 ± 0.5)° and (110) diffraction peaks with a diffraction angle 2θ at (65 ± 0.5)°; The (108) diffraction peak and the (110) diffraction peak satisfy the following relational expression: Wherein, FWHM(108) is the full width at half maximum of the (108) diffraction peak; FWHM(110) is the full width at half maximum of the (110) diffraction peak.

2. The ternary material according to claim 1, wherein 0 < x ≤ 0.1, 0 < y ≤ 0.1, 0 < a ≤ 0.

02.

3. The ternary material according to any one of claims 1-2, wherein, The (108) diffraction peak and the (110) diffraction peak further satisfy:

4. The ternary material according to any one of claims 1-3, wherein, The (108) diffraction peak and the (110) diffraction peak further satisfy:

5. The ternary material according to any one of claims 1-4, wherein, In the X-ray diffraction spectrum of the ternary material, the full width at half maximum FWHM(108) of the (108) diffraction peak ranges from 0.1 to 0.15; and / or The full width at half maximum FWHM(110) of the (110) diffraction peak ranges from 0.1 to 0.

15.

6. A method for preparing the ternary material according to any one of claims 1-5, wherein, The method includes the following steps: 1) Mix a first lithium source with a transition metal precursor to obtain a first mixture, and add a gelling agent and a first dopant to the first mixture to obtain gel particles; wherein, the transition metal precursor includes nickel, cobalt, and manganese elements; the molar ratio of the nickel, cobalt, and manganese elements is (1 - x - y):x:y, 0 < x ≤ 0.1, 0 < y ≤ 0.3; the molar ratio of the lithium element in the first lithium source to the total molar amount of the nickel, cobalt, and manganese elements in the precursor is (0.3 - 0.9):1; 2) Mix the gel particles with a second lithium source to obtain a second mixture, and perform a first sintering on the second mixture in an oxygen-containing atmosphere to obtain a first sintered product; wherein, the molar ratio of the lithium element in the second lithium source to the total molar amount of the nickel, cobalt, and manganese elements in the precursor is (0.15 - 0.75):1; the first lithium source and the second lithium source can be the same or different; 3) Mix the first sintered product with an optional second dopant and perform a second sintering in an oxygen-containing atmosphere to obtain the ternary material; Wherein, the first dopant and the second dopant include M element, M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W, and B; the ratio of the total molar amount of M element in the first dopant and the second dopant to the total molar amount of nickel, cobalt, and manganese elements in the precursor is a:1, 0 < a ≤ 0.

05.

7. The method according to claim 6, wherein, The gelling agent includes a solvent, a complexing agent, and a polymer monomer; Wherein, based on the total mass of the gelling agent, the mass percentage of the solvent is 10wt% - 50wt%; the mass percentage of the complexing agent is 0.2wt% - 2wt%; the volume ratio of the polymer monomer to the solvent is (0.1 - 0.4):

1.

8. The method according to claim 6 or 7, wherein, The solvent includes at least one of anhydrous ethanol or deionized water; and / or The complexing agent includes sodium dodecyl sulfate; and / or The polymer monomer includes at least one of methyl methacrylate, styrene, or acrylonitrile; preferably methyl methacrylate.

9. According to the method of any one of claims 6 - 8, wherein, The first sintering includes: a first sintering temperature of 600°C to 950°C, a first sintering time of 8 h to 24 h, and a first cooling is carried out after the first sintering; and / or The second sintering includes, after the first cooling is completed, carrying out the second sintering in a pure oxygen atmosphere, with a second sintering temperature of 300°C to 750°C, a second sintering time of 3 h to 24 h, and a second cooling is carried out after the second sintering is completed.

10. A lithium-ion battery, comprising a positive electrode sheet, wherein the positive electrode sheet comprises the ternary material according to any one of claims 1-5, or the ternary material obtained by the preparation method of the ternary material according to any one of claims 6-9.

11. The lithium-ion battery according to claim 10, wherein The chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, where 0 < x ≤ 0.1, 0 < y ≤ 0.3, 0 < a ≤ 0.05, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W, and B; the ternary material comprises single crystal particles; in the X-ray diffraction spectrum of the positive electrode sheet, there are a (108) diffraction peak at a diffraction angle 2θ of (64 ± 0.5)° and a (110) diffraction peak at a diffraction angle 2θ of (65 ± 0.5)°; The (108) diffraction peak and the (110) diffraction peak satisfy the following relational expression: wherein, FWHM(108) is the full width at half maximum of the (108) diffraction peak; FWHM(110) is the full width at half maximum of the (110) diffraction peak.

12. An electrical device, wherein, Comprising the lithium-ion battery according to claim 10 or 11.

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