A ternary material, its preparation method, positive electrode, lithium-ion battery and electrical equipment.

Abstract

To overcome the technical problems existing in current ternary materials for lithium-ion batteries, this disclosure provides a ternary material with the chemical formula LiNi. 1‑x‑y Co x Mn y M a O2, 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 includes single crystal particles; in the X-ray diffraction spectrum of the ternary material, there are (108) diffraction peaks at a diffraction angle 2θ of 64 ± 0.5° and (110) diffraction peaks at a diffraction angle 2θ of 65 ± 0.5°, and satisfy the following relationship: The ternary material provided in this disclosure has good crystallinity and layered structure stability, thereby enabling the prepared lithium-ion battery to have high cycle life, rate performance and energy density.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically relating to a ternary material, its preparation method, a positive electrode, a lithium-ion battery, and electrical equipment. Background Technology

[0002] As a crucial component of lithium-ion batteries, the cathode material is also a key factor affecting their performance. Lithium nickel manganese cobalt oxide (a ternary material) combines the advantages of lithium manganese oxide, lithium cobalt oxide, and lithium nickel oxide, exhibiting high specific capacity and excellent discharge rate, making it the primary cathode material for lithium-ion batteries currently available.

[0003] The main development trend of ternary materials is single crystallization. Single crystal particles can reduce grain boundary cracking during the cycling process of ternary materials and improve their cycle life. However, the preparation of single crystal materials requires higher sintering temperatures. High temperatures can easily cause lithium-nickel mixing, and 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

[0004] In view of this, the first aspect of this disclosure provides a ternary material, the chemical formula of which 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, 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 ternary material, there are (108) diffraction peaks at diffraction angle 2θ at (64 ± 0.5)° and (110) diffraction peaks at diffraction angle 2θ at (65 ± 0.5)°; the (108) diffraction peaks and the (110) diffraction peaks satisfy the following relationship: Wherein, FWHM(108) is the half-width of the (108) diffraction peak; FWHM(110) is the half-width of the (110) diffraction peak.

[0005] The ternary material provided in this disclosure, because it contains the crystal structure features required by this disclosure, has the following effects: First, it ensures that the ternary material has a stable layered structure and a reasonable atomic arrangement during charging and discharging, thereby giving the ternary material a high energy density and cycle life; Second, it can also reduce the contact area between the ternary material and the electrolyte, effectively suppress the occurrence of side reactions during cycling, enhance the structural stability of the ternary material, and further improve the cycle life of the battery.

[0006] Secondly, this 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 nickel, cobalt, and manganese elements is (1-xy):x:y, 0<x≤0.1, 0<y≤0.3; the molar ratio of lithium element in the first lithium source to the total of 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 performing a first sintering of the second mixture in an oxygen-containing atmosphere to obtain a first sintering product. The first lithium source and the second lithium source have a molar ratio of lithium to nickel, cobalt and manganese in the precursor of (0.15-0.75):1; the first lithium source and the second lithium source can be the same or different; 3) the first sintering product is mixed with an optional second dopant and sintered a second time in an oxygen-containing atmosphere to obtain the ternary material; wherein the first dopant and the second dopant include element M, 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 element M in the first dopant and the second dopant to the sum of the molar amounts of nickel, cobalt and manganese in the precursor is a:1, 0 < a ≤ 0.05.

[0007] Thirdly, this disclosure provides a positive electrode sheet comprising the ternary material described above, or the ternary material obtained by the above preparation method.

[0008] Fourthly, this disclosure provides a positive electrode sheet, the positive electrode sheet comprising a ternary material, the chemical formula of which 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, 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, there are (108) diffraction peaks at diffraction angle 2θ at (64 ± 0.5)° and (110) diffraction peaks at diffraction angle 2θ at (65 ± 0.5)°; the (108) diffraction peaks and the (110) diffraction peaks satisfy the following relationship: Wherein, FWHM(108) is the half-width of the (108) diffraction peak; FWHM(110) is the half-width of the (110) diffraction peak.

[0009] The lithium-ion battery cathode sheet disclosed herein, in addition to possessing the excellent effects of the aforementioned ternary materials, also exhibits high compaction density and excellent electrode processing performance.

[0010] Fifthly, this disclosure provides a lithium-ion battery including the aforementioned positive electrode.

[0011] Sixthly, this disclosure provides an electrical device including the aforementioned lithium-ion battery. Attached Figure Description

[0012] The accompanying drawings are provided to further understand the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof.

[0013] Figure 1 This is a 10,000x magnified SEM image of the transition metal precursor in Embodiment 1 of this disclosure;

[0014] Figure 2 This is a 50,000x magnified SEM image of the transition metal precursor in Embodiment 1 of this disclosure;

[0015] Figure 3 This is a 10,000x magnified SEM image of the ternary material prepared in Example 1 of this disclosure. Detailed Implementation

[0016] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0017] Lithium nickel cobalt manganese oxide (a ternary material) combines the advantages of lithium manganese oxide, lithium cobalt oxide, and lithium nickel oxide, and is widely used in lithium-ion batteries. In the crystal structure of ternary materials, transition metal ions and lithium ions alternately occupy the octahedral voids, arranged in layers. This atomic arrangement gives ternary materials excellent electrochemical performance. Single crystallization is one of the main directions in the development of ternary materials. Single crystal particles can reduce grain boundary cracking during material cycling and improve the cycle life of ternary materials. However, preparing single crystals requires higher sintering temperatures, and high temperatures can easily cause lithium-nickel mixing, thereby degrading the specific capacity and cycle life of the material.

[0018] The first embodiment of the present invention provides a ternary material, wherein the chemical formula of the ternary material is LiNi. 1-x- y Co x Mn y M aO2, 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, Al, Y, W, and B; the ternary material comprises single crystal particles; in the X-ray diffraction spectrum of the ternary material, there are (108) diffraction peaks at diffraction angle 2θ at (64 ± 0.5)° and (110) diffraction peaks at diffraction angle 2θ at (65 ± 0.5)°; the (108) diffraction peaks and the (110) diffraction peaks satisfy the following relationship: Wherein, FWHM(108) is the half-width of the (108) diffraction peak; FWHM(110) is the half-width of the (110) diffraction peak.

[0019] Ternary materials belong to the hexagonal crystal system. Among them, the (110) crystal plane is related to the a and b axes, while the (108) crystal plane is strongly related to the c axis. Furthermore, the combination of the (110) and (108) crystal planes can reflect the characteristics of the ternary material unit cell in the three directions of a, b, and c axes, and can be used to evaluate the crystal structure of ternary materials. It can roughly determine the orderliness of the layered structure of ternary materials and evaluate the rationality of the atomic arrangement between each layer. In the XRD pattern of ternary materials, the two diffraction peaks of the (108) and (110) crystal planes show obvious crack peaks, which is a sign that the crystal structure of ternary materials has reached a suitable range. At this time, a regular layered structure of alternating transition metals and lithium is formed in the ternary material.

[0020] Through extensive experimental research, the inventors of this disclosure have discovered that when the X-ray diffraction spectrum of a single-crystal ternary material contains a (108) diffraction peak with a diffraction angle 2θ of (64±0.5)° and a (110) diffraction peak with a diffraction angle 2θ of (65±0.5)°, and the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: In ternary materials, the alternating arrangement of transition metals and lithium is more regular, with less lithium-nickel mixing, resulting in higher specific capacity; moreover, the layer structure formed by the alternating transition metals and lithium is more stable, which can ensure that ternary materials have a high cycle life.

[0021] In this application, single-crystal particles are defined in contrast to polycrystalline particles; in terms of morphology, single-crystal particles are individually dispersed or quasi-individually dispersed particles; polycrystalline particles are secondary particles formed by the agglomeration of multiple primary particles.

[0022] Specifically, in the formula, 2θ(110) refers to the specific position of the (110) diffraction peak in the X-ray diffraction spectrum actually obtained when performing XRD tests on ternary materials. Similarly, 2θ(108) refers to the specific position of the (108) diffraction peak in the X-ray diffraction spectrum actually obtained when performing XRD tests on ternary material powder.

[0023] In some preferred embodiments of this disclosure, the ternary material has the chemical formula LiNi. 1-x-y Co x Mn y M a O2, where 0 < x ≤ 0.1, 0 < y ≤ 0.1, and 0 < a ≤ 0.02.

[0024] As the Ni content in ternary materials increases, the specific capacity of the ternary materials increases significantly. However, with a higher Ni content, the risk of lithium-nickel mixing also increases, leading to a decrease in cycle life. Therefore, satisfying the above relationship can ensure the stability of the high-nickel ternary material layer structure and the orderly arrangement of interlayer transition metal elements and lithium, enabling the ternary material to have both higher specific capacity and high cycle life.

[0025] In some preferred embodiments of this disclosure, the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship:

[0026] In some preferred embodiments of this disclosure, the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: Within the above-mentioned preferred range, the ternary material has a higher degree of order in its layered structure and a higher stability in the atomic arrangement between the transition metal layers, which enables the ternary material to have a higher specific capacity while also having a high cycle life.

[0027] In some preferred embodiments of this disclosure, the half-width at half-maximum (FWHM) of the (108) diffraction peak in the X-ray diffraction spectrum of the ternary material ranges from 0.1 to 0.15.

[0028] Specifically, the half-maximum width (FWHM)(108) of the (108) diffraction peak refers to the peak width of the (108) diffraction peak at a position parallel to the diffraction angle 2θ axis and at half-maximum height in the X-ray diffraction spectrum. With FWHM(108) ranging from 0.1 to 0.15, the prepared ternary material does not contain quasicrystals, exhibits good single-crystal characteristics, has unobstructed lithium-ion insertion / extraction channels, and good rate performance.

[0029] In some preferred embodiments of this disclosure, the half-width at half-maximum (FWHM) (110) of the (110) diffraction peak at a diffraction angle 2θ of (65±0.5)° in the X-ray diffraction spectrum of the ternary material ranges from 0.1 to 0.15. Specifically, the half-width at half-maximum (FWHM) (110) of the (110) diffraction peak refers to the peak width of the (110) diffraction peak at a position parallel to the axis of diffraction angle 2θ and at half-maximum height of the (110) diffraction peak in the X-ray diffraction spectrum. When FWHM (110) is in the range of 0.1 to 0.15, the prepared ternary material does not contain quasi-crystals, has good single-crystal characteristics, unobstructed lithium-ion insertion / extraction channels, and good rate performance.

[0030] In some preferred embodiments of this disclosure, the ternary material has an α-NaFeO2 layered structure.

[0031] It is understood that the X-ray diffraction pattern of the ternary material in this disclosure can be obtained by scanning at a scanning rate of 2 to 5° / min in the range of 3° to 90° using a copper target X-ray generator.

[0032] In some preferred embodiments of this disclosure, the particle size (D50) of the ternary material is 2μm-6μm. Within this particle size range, the ternary material can be guaranteed to have better mechanical strength and compaction density.

[0033] In a second aspect, this 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 nickel, cobalt, and manganese elements is (1-xy):x:y, 0<x≤0.1, 0<y≤0.3; the molar ratio of lithium element in the first lithium source to the total amount of 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 performing a first sintering of the second mixture in an oxygen-containing atmosphere to obtain a first sintering product. The first lithium source and the second lithium source have a molar ratio of lithium to nickel, cobalt and manganese in the precursor of (0.15-0.75):1; the first lithium source and the second lithium source can be the same or different; 3) the first sintering product is mixed with an optional second dopant and sintered a second time in an oxygen-containing atmosphere to obtain the ternary material; wherein the first dopant and the second dopant include element M, 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 element M in the first dopant and the second dopant to the sum of the molar amounts of nickel, cobalt and manganese in the precursor is a:1, 0 < a ≤ 0.05.

[0034] The ternary material preparation method disclosed herein has the following advantages compared with the prior art: First, the use of a gelling agent pretreatment process allows lithium elements to approach the lithium sites after sintering in advance and form van der Waals forces, ensuring that lithium and nickel, cobalt, and manganese are more regularly combined in the crystal lattice during subsequent sintering, resulting in higher crystallinity, more complete crystal form, less internal stress, and less likelihood of internal lattice dislocations; Second, the stepwise lithium mixing and / or doping process makes the mixing of lithium ions and / or doping elements with the transition metal precursor more uniform, and their arrangement after embedding into the ternary material lattice is more orderly, thereby making the crystallinity of the ternary material consistent inside and outside, which is more conducive to the formation of single crystal materials; Third, the stepwise sintering process allows for multiple adjustments to the sintering temperature, balancing the negative impact of continuous high temperature on the lithium-nickel mixing of single crystal materials.

[0035] 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 adding the dopant; the dopant can be added first and mixed with the first mixture before adding the gelling agent; or the gelling agent and the dopant can be added simultaneously and mixed with the first product.

[0036] Specifically, transition metal precursors are suitable for preparing ternary single crystal particles.

[0037] In some preferred embodiments of this disclosure, the D50 of the transition metal precursor is approximately 2μm-6μm, and its morphology consists of small, nearly spherical aggregates. The primary particles are relatively coarse, and after subsequent sintering and pulverization, the aggregates are broken up. Therefore, the morphology of the single-crystal precursor is not inherited by the ternary single-crystal particles. The preferred pulverization method is airflow milling.

[0038] In some preferred embodiments of this disclosure, the nickel-cobalt-manganese precursor includes at least one of a hydroxide precursor or a carbonate precursor.

[0039] In some preferred embodiments of this 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.

[0040] In this disclosure, in some preferred embodiments, the first dopant and the second dopant may be the same or different. The dopant is a compound containing a dopant element. The dopant element includes element M, which is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W, and B. Optionally, the compound containing the dopant element 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. These dopant elements have radii similar to transition metal ions and possess strong binding energies with oxygen, resulting in a more stable crystal structure in the ternary material and facilitating a reduction in the ion diffusion resistance of the single-crystal ternary material.

[0041] In some preferred embodiments of this disclosure, the molar ratio of lithium to M in the lithium compound 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 dopant element within the above range, the effectiveness of element doping can be improved. Appropriate element 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 in the ternary material during charging and discharging, reduce the number of times lithium ions pass through grain boundaries during insertion and extraction, and make lithium ions more rapidly inserted and extracted during cycling, thereby improving the structural stability and rate performance of the material.

[0042] In some preferred embodiments of this disclosure, the gelling agent comprises a solvent, a complexing agent, and a polymer monomer; wherein the solvent comprises 10 wt% to 50 wt% of the gelling agent by mass; 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, allowing lithium ions to be uniformly dispersed on the surface of the transition metal precursor, facilitating lithiation.

[0043] In some preferred embodiments of this disclosure, the complexing agent comprises 0.2 wt% to 2 wt% of the gelling agent by mass; the complexing agent includes sodium dodecyl sulfate (SDS). The complexing agent facilitates the binding of the gelling agent to the lithium source, and the mass percentage of the complexing agent within the aforementioned range is beneficial for the dispersion of the lithium source in the gelling agent, thus facilitating the formation of a more stable ternary material.

[0044] In some preferred embodiments of this disclosure, 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 gel formation. 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, facilitating improved crystallinity after lithiation. Specifically, the methyl methacrylate mixing process polymerizes into polymethyl methacrylate, which has higher dispersibility for the lithium source and better adhesion to the surface of the metal precursor. Simultaneously, the residual carbon content of the finished product after sintering of polymethyl methacrylate ranges from 0.1% wt to 3% wt. This range of residual carbon content is beneficial for further improving rate performance.

[0045] In some preferred embodiments of this disclosure, during the process of adding a gelling agent and optional dopant to the first mixture to obtain gel particles, appropriate heating treatment can be performed at a temperature of 40°C to 80°C, which is conducive to the polymerization reaction.

[0046] In some preferred embodiments of this disclosure, the first sintering includes: a first sintering temperature of 600℃~950℃, a first sintering time of 8h~24h, and a first cooling after the first sintering.

[0047] In some preferred embodiments of this disclosure, the second sintering includes: after the first cooling, performing a second sintering in a pure oxygen atmosphere at a temperature of 300℃ to 750℃ for 3 hours to 24 hours, followed by a second cooling. This double sintering method results in high crystallinity of the ternary material, and the double cooling method controls the grain size of the intermediate product, allowing the ternary material grains to quickly stabilize within a suitable size range. This is beneficial for increasing the compaction density of the ternary material, while also preventing the formation of other impurities and improving the ordered layered structure of the ternary material. The double sintering and cooling method saves cooling time in the sintering equipment, shortens the process time, and is also beneficial for obtaining a highly ordered layered structure in the ternary material, resulting in a higher specific capacity.

[0048] In some embodiments, the first sintering further includes: a heating rate of 1℃ / min-8℃ / min during the first sintering, a first sintering temperature of 600℃-950℃, a first sintering time of 8h-24h, and a first cooling after the first sintering is completed. The first cooling temperature is 20-30℃, and the cooling method is rapid cooling, directly transferring the first sintering product after sintering to room temperature.

[0049] The first sintering of the transition metal precursor helps to form a ternary material with better crystallinity. Simultaneously, the carbonization of the transition metal precursor's polymer coating layer increases the material's true density and adjusts its specific surface area. Following the first sintering, a first cooling operation is performed to control the grain size of the intermediate product, ensuring the grains quickly stabilize at a fixed size. This guarantees rapid crystallization of the ternary material, avoids the formation of other impurities, and improves the ordered layered structure of the ternary material.

[0050] In some embodiments, the second sintering includes: a heating rate of 1℃ / min-8℃ / min, a second sintering temperature of 300℃-750℃, a second sintering time of 3h-24h, and a second cooling after the second sintering is completed. The second cooling temperature is 20-30℃, and the cooling method is rapid cooling, directly transferring the second sintering product after completion to room temperature.

[0051] Specifically, a pure oxygen atmosphere environment refers to a space filled with pure oxygen, and the second sintering is carried out in this oxygen-filled space. The first and second sintering serve the same purpose: to help form ternary materials with better crystallinity and improve their density. The first and second cooling also serve the same purpose: to control the grain size of the intermediate products, quickly stabilizing the ternary material grains to a fixed size, increasing the compaction density during electrode fabrication, and ensuring rapid crystallization to prevent the formation of other impurities, thus improving the ordered layered structure of the ternary material. It is understood that the equipment used for the first and second sintering includes one of the following: tube furnace, box furnace, fluidized bed furnace, rotary kiln, microwave oven, or tunnel furnace.

[0052] In some preferred embodiments of this disclosure, the preparation method of the ternary material further includes a third sintering after cooling following the second sintering. The third sintering temperature is 300-500°C, and the sintering time is 3-8 hours. Optionally, a lithium source and / or a dopant may be added during the third sintering. The third sintering is primarily intended to form a more stable ternary material with higher crystallinity.

[0053] In a third aspect, this disclosure provides a positive electrode sheet comprising the ternary material provided in the first aspect, or the ternary material prepared by the method for preparing the ternary material provided in the second aspect.

[0054] The cathode sheet disclosed herein contains the aforementioned ternary material and exhibits high specific capacity and cycle life.

[0055] The positive electrode sheet prepared using the above ternary materials is applied to the battery, which has high energy density and cycle life.

[0056] In some preferred embodiments of this disclosure, the compaction density of the positive electrode sheet is 3.2 g / cm³. 3 ~3.5g / cm 3 .

[0057] The positive electrode sheet prepared using the ternary material disclosed herein has a relatively complete layered structure and a high compaction density. When applied to batteries, it can improve the energy density and cycle life of the batteries.

[0058] In a fourth aspect, this disclosure provides a positive electrode sheet comprising a ternary material, said ternary material having the chemical formula LiNi. 1-x-y Co x Mn y M a O2, 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, Al, Y, W, and B; the ternary material comprises single crystal particles; in the X-ray diffraction spectrum of the positive electrode, there are (108) diffraction peaks at diffraction angle 2θ at (64 ± 0.5)° and (110) diffraction peaks at diffraction angle 2θ at (65 ± 0.5)°; the (108) diffraction peaks and the (110) diffraction peaks satisfy the following relationship: Wherein, FWHM(108) is the half-width of the (108) diffraction peak; FWHM(110) is the half-width of the (110) diffraction peak.

[0059] In a fifth aspect, this disclosure provides a lithium-ion battery including the aforementioned positive electrode. The lithium-ion battery using this disclosure exhibits high energy density and cycle life.

[0060] The lithium-ion battery also includes a negative electrode, a diaphragm, and an electrolyte. The negative electrode includes 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 includes a negative electrode active material, a conductive agent, and a binder.

[0061] The negative electrode active material includes carbon-based materials; carbon-based materials include one or more of artificial graphite, natural graphite, hard carbon materials or soft carbon materials.

[0062] Negative electrode active materials also include one or more of silicon-based materials, tin-based materials, and lithium titanate materials. Silicon-based materials can be elemental silicon or silicon oxide (SiO₂). x Tin-based materials can be elemental tin, tin oxide (SnO), or a combination of one or more of the following: 0 < x < 2, silicon alloys, etc. x One or more combinations of 0 < x ≤ 2 and tin alloys. Lithium titanate material can be Li4Ti5O 12 wait.

[0063] The adhesive can be one or a combination of styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylic ethylene acrylic acid (PEAA), sodium alginate, carboxymethyl chitosan, polyacrylonitrile (PAN), and polyvinyl alcohol (PVA).

[0064] 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.

[0065] The diaphragm can be a composite membrane made of one or more of polyethylene, polypropylene, and polyvinylidene fluoride.

[0066] The electrolyte is an organic solvent that dissolves charge-carrying ions. This disclosure does not impose any restrictions on the electrolyte; it can be formulated according to actual conditions.

[0067] According to a sixth aspect of this disclosure, an electrical device is provided, including the aforementioned lithium-ion battery.

[0068] Electrical devices prepared using the lithium-ion batteries disclosed herein can have higher market competitiveness.

[0069] In some embodiments of this disclosure, the aforementioned electrical equipment includes, but is not limited to, mobile phones, laptops, tablets, smartwatches and other wearable electronic devices, e-cigarettes, as well as new energy vehicles, electric bicycles, etc.

[0070] The present invention will be further described in detail below through examples.

[0071] Example 1

[0072] This embodiment illustrates the ternary material and its preparation method disclosed in this invention, including the following steps:

[0073] 1) Using Ni 0.92 Co 0.06 Mn 0.02The hydroxide precursor was prepared using LiOH as the lithium source. First, lithium hydroxide was added at a lithium:transition metal element ratio of 0.4 and mixed to obtain a first mixture. Then, titanium dioxide powder (calculated as 1250 ppm based on titanium molar content), zirconium oxide powder (calculated as 2500 ppm based on zirconium molar content), tantalum pentoxide (calculated as 1000 ppm based on tantalum molar content), and yttrium oxide powder (calculated as 1000 ppm supplementary content based on yttrium molar content) were added to the first mixture and mixed at high speed for 8 hours. The mixture was then poured into a ball mill and ball-milled with anhydrous ethanol for 8 hours. Afterwards, 0.4 wt% sodium dodecyl sulfate, 30 wt% H2O, and methyl methacrylate (0.25 volume ratio to water) were added to the mixture and stirred for 1 hour to obtain a gel-like mixture of the precursor, lithium salt, and dopant. This mixture was heated to 80°C and held for 1 hour to collect the gel particles.

[0074] 2) Then the gel particles were mixed with LiOH again at a high speed according to the ratio of lithium:transition metal element = 0.63, and then the first sintering was carried out in an oxygen atmosphere. The heating rate was 5℃ / min, the sintering temperature was 800℃, and the sintering time was 18h. After that, the product was crushed and sieved to obtain the first sintered product.

[0075] 3) The first sintered product was mixed with alumina powder (calculated based on the molar content of aluminum element, which is 1500ppm) and sintered for a second time. The heating rate was 5℃ / min, the sintering temperature was 700℃, the sintering time was 10h, and the product was crushed and sieved in an oxygen atmosphere to obtain the second sintered product.

[0076] 4) The second sintering product was mixed with boric acid (calculated to be 1000 ppm based on the molar content of boron) and tungstic acid powder (calculated to be 1000 ppm based on the molar content of tungsten), and sintered at 300°C in an oxygen atmosphere for 5 hours. After pulverization, the final ternary material was obtained.

[0077] Among them, Ni 0.92 Co 0.06 Mn 0.02 The hydroxide precursor has a D50 of 4 μm, and its SEM images at different magnifications are shown below. Figure 1 and Figure 2 As shown, in low-magnification SEM ( Figure 1 Ni 0.92 Co 0.06 Mn 0.02 The hydroxide precursor is composed of secondary spherical particles formed by the aggregation of primary particles; in high-magnification SEM ( Figure 2 The primary particles are relatively coarse. The resulting ternary material product (LiNi) is... 0.90 Co 0.05 Mn 0.05The D50 of O2 is 4 μm, and its SEM is as follows: Figure 3 LiNi 0.92 Co 0.06 Mn 0.02 MO2 did not inherit Ni 0.92 Co 0.06 Mn 0.02 Instead of exhibiting the morphology of the hydroxide precursor, it forms irregular primary particles.

[0078] The finished ternary material was subjected to XRD testing using a copper target X-ray generator, with scanning at a rate of 3° / min in the range of 10–80°.

[0079] Example 2

[0080] The difference between Example 2 and Example 1 is that titanium dioxide and tantalum pentoxide are not added during the sintering in step 1).

[0081] Example 3

[0082] The difference between Example 3 and Example 1 is that aluminum oxide is not added in step 2).

[0083] Example 4

[0084] The difference between Example 4 and Example 1 is that tungstic acid is not added in step 4).

[0085] Example 5

[0086] The difference between Example 5 and Example 1 is that tantalum pentoxide and yttrium oxide powder are not added in step 1); aluminum oxide is not added in step 2); and step 4 is not performed.

[0087] Example 6

[0088] Example 6 differs from Example 1 in that it uses Ni 0.89 Co 0.06 Mn 0.06 The precursor was sintered at a ratio of 770℃ for 16 hours in the first sintering stage and at 620℃ for 8 hours in the second sintering stage.

[0089] Example 7

[0090] The difference between Example 7 and Example 1 is that in step 1), lithium hydroxide is added at a ratio of lithium to transition metal element = 0.9; and in step 2), lithium hydroxide is added at a ratio of lithium to transition metal element = 0.15.

[0091] Example 8

[0092] Example 8 differs from Example 1 in that, in step 1), 2 wt% sodium dodecyl sulfate (SDS), 50 wt% H2O, and methyl methacrylate (MMA) in a volume ratio of 0.4 with water are added to the mixture.

[0093] Example 9

[0094] The difference between Example 9 and Example 1 is that, in step 1), 0.2 wt% sodium dodecyl sulfate (SDS), 10 wt% H2O, and methyl methacrylate (MMA) in a volume ratio of 0.1 with water are added to the mixture.

[0095] Example 10

[0096] The difference between Example 10 and Example 1 is that, in step 1), 0.8 wt% sodium dodecyl sulfate (SDS), 40 wt% H2O, and methyl methacrylate (MMA) in a volume ratio of 0.5 with water are added to the mixture.

[0097] Comparative Example 1

[0098] The difference between Comparative Example 1 and Example 1 is that the gel coating treatment in Example 1 was not performed.

[0099] Comparative Example 2

[0100] The difference between Comparative Example 2 and Example 1 is that the element doping, gel coating treatment and lithium source addition in Example 1 were not performed. In the first mixing process, lithium hydroxide was added in a ratio of lithium to transition metal element = 1.05.

[0101] Comparative Example 3

[0102] The difference between Comparative Example 3 and Example 6 is that the gel coating treatment and lithium addition in stages were not performed as in Example 6; lithium hydroxide was added in a ratio of lithium:transition metal element = 1.05.

[0103] Comparative Example 4

[0104] The difference between Comparative Example 4 and Example 1 is that Ni is used. 0.74 Mn 0.26 The precursor was sintered at 820°C for 14 hours and at 600°C for 8 hours. The fractional addition of lithium and doping treatment as in Example 1 were not performed. Lithium hydroxide was added at a ratio of lithium to transition metal element = 1.05.

[0105] The specific data of FWHM(108), FWHM(110), 2θ(108), and 2θ(110) in the XRD spectra of the ternary materials prepared in Examples 1-10 and Comparative Examples 1-4 are recorded in Table 1. The XRD half-width and peak position data are obtained from the analysis of the original XRD test file by the processing software MDIJade 6. The specific data are shown in Table 1.

[0106] Table 1. Partial data of ternary materials in Examples 1-10 and Comparative Examples 1-4.

[0107]

[0108]

[0109]

[0110]

[0111] A positive electrode S containing ternary materials from Examples 1 and 7 and Comparative Examples 1 and 4 was selected. The specific data of FWHM(108), FWHM(110), 2θ(108), and 2θ(110) in the XRD spectrum obtained after XRD testing of the above positive electrode are recorded in Table 2. The XRD half-width and peak position data are obtained from the analysis of the original XRD test file by the processing software MDIJade 6. The specific data are shown in Table 2.

[0112] Table 2. Data for the positive electrode plate

[0113]

[0114] Performance testing:

[0115] The ternary materials prepared in Examples 1-10 and Comparative Examples 1-4 were used to prepare positive electrode sheets and batteries, and the following tests were performed.

[0116] Specific capacity test: The above ternary material was 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 then coated onto aluminum foil using a coating machine, dried, and cold-pressed to obtain a compacted density of 3.40 g / cm³. 3 The positive electrode was dried at 120℃ for 24 hours. A coin cell 2032 was assembled using a lithium sheet as the negative electrode, a Cellgard 2300 porous membrane as the separator, and a 1 mol / L LiPF6 + DMC (volume ratio 1:1) mixed electrolyte as the electrolyte. The cells were then tested at a charge-discharge rate of 0.2C, and the specific capacity of the third discharge test was taken as the specific capacity of the ternary material.

[0117] Battery fabrication: The positive electrode sheet, negative electrode sheet, and separator obtained above are used to make bare cells according to conventional manufacturing processes. The bare cells are dried, injected with electrolyte, and packaged to finally make a battery.

[0118] In this process, artificial graphite, conductive carbon black, thickener (CMC), and binder (SBR) are mixed in a ratio of 96:1:1:2. The powder and deionized water are then stirred together using a homogenizer to form a negative electrode slurry, which is then uniformly coated onto copper foil to obtain the negative electrode sheet.

[0119] Room temperature cycle performance test: The cells obtained after formation are subjected to a room temperature 25℃ cycle test, and a charge and discharge test is performed at 0.5C / 0.5C. The discharge capacity retention after 500 cycles is recorded.

[0120] DC internal resistance (DCIR) test: The formed cells are subjected to a high temperature 45°C cycle test, a 1C / 1C charge and discharge test, and the DCIR of the battery is recorded after 500 cycles.

[0121] Table 2 Performance data of Examples 1-10 and Comparative Examples 1-4

[0122]

[0123] As can be seen from the data in Table 3, the ternary material provided in the embodiments of this disclosure meets the crystal structure characteristics required by this disclosure, and the discharge capacity, cycle performance, and DCIR of the battery are improved compared with the comparative ratio.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

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; The X-ray diffraction spectrum of the ternary material has a (108) diffraction peak at a diffraction angle of (64±0.5)° and a (110) diffraction peak at a diffraction angle of (65±0.5)°. The (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: 0.5 < <0.8; Wherein, FWHM(108) is the half-peak width of the (108) diffraction peak; FWHM(110) is the half-peak width of the (110) diffraction peak; the half-peak width of the (108) diffraction peak FWHM(108) ranges from 0.1 to 0.15; the half-peak width of the (110) diffraction peak FWHM(110) ranges from 0.1 to 0.

15.

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 claim 1, wherein, The (108) diffraction peak and the (110) diffraction peak further satisfy: 0.6 < <0.

7.

4. The ternary material according to claim 1, wherein, The (108) diffraction peak and the (110) diffraction peak further satisfy: 0.62 < <0.

65.

5. A method for preparing a ternary material as described in any one of claims 1-4, wherein, Includes the following steps: 1) A first lithium source is mixed with a transition metal precursor to obtain a first mixture, and in the first mixture... A gelling agent and a first dopant are added to obtain gel particles; wherein the transition metal precursor includes nickel, cobalt, and manganese; the molar ratio of nickel, cobalt, and manganese is (1-xy):x:y, 0<x≤0.1, 0<y≤0.3; the molar ratio of lithium in the first lithium source to the total amount of nickel, cobalt, and manganese in the precursor is (0.3-0.9):1; 2) The gel particles are mixed with a second lithium source to obtain a second mixture, and the second mixture is sintered for the first time in an oxygen-containing atmosphere to obtain a first sintered product; wherein, the molar ratio of lithium in the second lithium source to the total amount of nickel, cobalt and manganese 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) The first sintering product is mixed with the second dopant and then sintered a second time in an oxygen-containing atmosphere to obtain the ternary material; Wherein, the first dopant and the second dopant include element M, 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 element M in the first dopant and the second dopant to the sum of the molar amounts of nickel, cobalt and manganese in the precursor is a:1, 0 < a ≤ 0.

05.

6. The method for preparing ternary materials according to claim 5, wherein, The gelling agent comprises a solvent, a complexing agent, and a polymer monomer; 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%; and the volume ratio of the polymer monomer to the solvent is (0.1~0.4):

1.

7. The method for preparing ternary materials according to claim 6, wherein, The solvent includes at least one of anhydrous ethanol or deionized water; The complexing agent includes sodium dodecyl sulfate; the polymer monomer includes at least one of methyl methacrylate, styrene, or acrylonitrile.

8. The method for preparing ternary materials according to claim 7, wherein, The polymer monomer is methyl methacrylate.

9. The method for preparing ternary materials according to claim 7, wherein, The first sintering includes: a first sintering temperature of 600℃~950℃, a first sintering time of 8h~24h, and a first cooling after the first sintering; the second sintering includes: after the first cooling, a second sintering is carried out in a pure oxygen atmosphere, a second sintering temperature of 300℃~750℃, a second sintering time of 3h~24h, and a second cooling after the second sintering.

10. A positive electrode plate, wherein, Includes the ternary material as described in any one of claims 1-4.

11. A positive electrode plate, wherein, Including ternary materials, The ternary material has the chemical formula 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; The X-ray diffraction spectrum of the positive electrode has a (108) diffraction peak at a diffraction angle of (64±0.5)° and a (110) diffraction peak at a diffraction angle of (65±0.5)°. The (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: 0.5 < <0.8; Wherein, FWHM(108) is the half-peak width of the (108) diffraction peak; FWHM(110) is the half-peak width of the (110) diffraction peak; the half-peak width FWHM(108) of the (108) diffraction peak ranges from 0.1 to 0.15; the half-peak width FWHM(110) of the (110) diffraction peak ranges from 0.1 to 0.

15.

12. A lithium-ion battery, wherein, This includes the positive electrode sheet as described in claim 10 or the positive electrode sheet as described in claim 11.

13. An electrical appliance, wherein, Including the lithium-ion battery of claim 12.

Images