A ternary material, a preparation method thereof, a positive plate, a lithium ion battery and an electric device

Abstract

To overcome the technical problems existing in the prior art ternary material, the present 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 ≤ 0.1, 0 < a ≤ 0.05, M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, W, Al and B; the ternary material comprises polycrystalline particles; in the X-ray diffraction spectrum of the ternary material, the (108) diffraction peak at a diffraction angle 2θ of (64±0.5)° and the (110) diffraction peak at a diffraction angle 2θ of (65±0.5)° satisfy the following relationship: The present disclosure provides a ternary material, and the satisfaction of this relationship can ensure that the material has good crystallinity and stability of layered structure, so that the prepared ternary material has high cycle life, rate performance and specific capacity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy storage, and particularly relates to a ternary material, a preparation method thereof, a positive electrode sheet, a lithium ion battery and an electric equipment. BACKGROUND

[0002] The positive electrode material of a lithium ion battery is an important component of the lithium ion battery and is one of the key factors affecting the performance of the lithium ion battery. Lithium nickel cobalt manganese oxide (ternary material) combines the advantages of lithium manganate, lithium cobaltate and lithium nickelate, has high specific capacity and good discharge rate, and is a main positive electrode material of the lithium ion battery.

[0003] High nickelization is a main development trend of the ternary material, and can improve the specific capacity of the ternary material. However, the ionic radius of nickel ions is close to that of lithium ions, which can easily cause lithium-nickel mixing, and the higher the nickel content, the more serious the mixing phenomenon, thereby affecting the order of the structure of the ternary material and leading to poor cycle performance of the ternary lithium battery. It is of great significance to prepare a high-nickel ternary material with high specific capacity and long cycle life. SUMMARY

[0004] In view of this, the first aspect of the present application provides a ternary material, 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 < 0.1, 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 polycrystalline particles; in the X-ray diffraction spectrum of the ternary material, 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)°; and the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: wherein FWHM(108) is the half-peak width of the (108) diffraction peak at a diffraction angle 2θ of (64±0.5)°; and FWHM(110) is the half-peak width of the (110) diffraction peak at a diffraction angle 2θ of (65±0.5)°.

[0005] The ternary material provided by the present application has the following effects because it contains the structural features required by the present application: first, it has a high nickel content, which ensures that the ternary material has a high specific capacity; second, the doping elements are modified to enhance the binding energy of the transition metal elements, effectively inhibit the dissolution of nickel ions and the mixing of lithium and nickel during the cycle process, and increase the cycle stability; third, it has good layer structure order and reasonable atomic arrangement, which further ensures high specific capacity and long cycle life.

[0006] In a second aspect, the present disclosure provides a preparation method of the ternary material, comprising the following steps: 1) mixing a first lithium source and a transition metal precursor to obtain a first mixture, and adding a first dopant to the first mixture to obtain a first doped mixture; wherein the transition metal precursor comprises nickel, cobalt and manganese elements; the molar ratio of the nickel, cobalt and manganese elements is (1-x-y):x:y, 0

[0007] In a third aspect, the present disclosure provides a positive electrode sheet, comprising the ternary material or the ternary material prepared by the preparation method of the ternary material.

[0008] In a fourth aspect, the present disclosure provides a positive electrode sheet, comprising a ternary material, the chemical formula of the ternary material is LiNi 1-x-y Co x Mn y M a O2, wherein 0 FWHM (108) is the half-peak width of the (108) diffraction peak at a diffraction angle 2θ = (64±0.5)°; and FWHM (110) is the half-peak width of the (110) diffraction peak at a diffraction angle 2θ = (65±0.5)°.

[0009] The positive electrode sheet of the lithium ion battery provided by the present disclosure has higher compaction density and excellent electrode processing performance in addition to the excellent effects of the ternary material.

[0010] In a fifth aspect, the present disclosure provides a lithium ion battery comprising the positive electrode sheet.

[0011] In a sixth aspect, the present disclosure provides an electrical equipment comprising the lithium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, which together with the specific embodiments described below, serve to explain the present disclosure but do not constitute a limitation thereof.

[0013] Figure 1 is a SEM image of the transition metal precursor in Example 1 of the present disclosure, magnified 10,000 times;

[0014] Figure 2 is a SEM image of the transition metal precursor in Example 1 of the present disclosure, magnified 50,000 times;

[0015] Figure 3 is a SEM image of the ternary material prepared in Example 1 of the present disclosure, magnified 10,000 times. DETAILED DESCRIPTION

[0016] In order to make the technical problems solved by the present disclosure, the technical solutions and the beneficial effects more clearly understood, the present disclosure will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present disclosure and do not limit the present disclosure.

[0017] The 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 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 form makes the ternary material have excellent electrochemical performance. High nickelization is one of the main directions of the development of ternary materials at present. High nickel content can increase the specific capacity of ternary materials and increase the cruising range of batteries. However, due to the close ion radius of nickel ions and lithium ions, lithium-nickel mixing is easily caused, and the higher the nickel content, the more serious the mixing phenomenon, which further affects the order of the structure of the ternary material and leads to poor cycle performance of the ternary lithium battery. It is of great significance to prepare high-nickel ternary materials with high specific capacity and long cycle life.

[0018] The first embodiment of the present application provides a ternary material, the chemical formula of the ternary material is LiNi 1-x- y Co x Mn y M a O2, wherein 0 Wherein, FWHM (108) is the half peak width of the (108) diffraction peak at diffraction angle 2θ=(64±0.5)°; FWHM (110) is the half peak width of the (110) diffraction peak at diffraction angle 2θ=(65±0.5)°.

[0019] The ternary material belongs to the hexagonal system, wherein the (110) crystal face is related to the a and b axes, and the (108) crystal face is more strongly related to the c axis; further, the combination of the (110) crystal face and the (108) crystal face can reflect the characteristics of the a, b and c axes in the unit cell of the ternary material, which 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 can also evaluate the rationality of the atomic arrangement between the layers. The two diffraction peaks of the (108) and (110) crystal faces in the XRD pattern of the ternary material appear obvious split peaks, which is a sign that the crystal structure of the ternary material reaches a suitable range. At this time, the regular lamellar structure formed by the alternation of transition metals and lithium in the ternary material. The present inventors have found through a large amount of research that when the (108) diffraction peak and the (110) diffraction peak satisfy the relationship: The transition metal and lithium in the ternary material are alternately arranged more regularly, the lithium-nickel mixed arrangement is less, and the specific capacity is higher; and the layer structure formed by the transition metal and lithium alternately is more stable, which can ensure that the ternary material has a high energy density and a long cycle life.

[0020] In the present application, the polycrystalline particle refers to a secondary spherical particle formed by agglomeration of a plurality of primary particles.

[0021] Specifically, 2theta (110) in the relationship refers to the specific position of the (110) diffraction peak in the X-ray diffraction spectrum actually obtained by XRD testing of the ternary material. Similarly, 2theta (108) refers to the specific position of the (108) diffraction peak in the X-ray diffraction spectrum actually obtained by XRD testing of the powder of the ternary material.

[0022] 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, wherein 0 < x ≤ 0.1, 0 < y ≤ 0.05, 0 < a ≤ 0.05, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W and B.

[0023] With the high content of Ni element in the ternary material, the specific capacity of the ternary material will increase significantly; however, with the high content of Ni element, the risk of lithium-nickel mixed arrangement also increases, resulting in a decrease in cycle life. Therefore, under the condition of satisfying the above relationship, the stability of the layer structure of the high-nickel ternary material and the order of the arrangement of the transition metal elements and lithium between the layers are ensured, so that the ternary material has a higher specific capacity while taking into account a high cycle life.

[0024] In some preferred embodiments of the present disclosure, the (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: Under the above preferred range of the relationship, the order of the layer structure of the ternary material is higher, and the stability of the atomic arrangement between the transition metal layers is also higher, so that the ternary material has a higher specific capacity while taking into account a high cycle life.

[0025] In some preferred embodiments of the present disclosure, in the X-ray diffraction spectrum of the ternary material, the half-peak width FWHM (108) of the (108) diffraction peak at a diffraction angle 2theta of (64±0.5)° is in the range of 0.1-0.2.

[0026] Specifically, the half-peak width FWHM(108) of the (108) diffraction peak at a diffraction angle 2θ of (64±0.5)° refers to the value of the half-peak width of the (108) diffraction peak at the position of the half-peak height of the (108) diffraction peak in the X-ray diffraction spectrum, which is parallel to the horizontal axis of the diffraction angle 2θ. The FWHM(108) ranges from 0.1 to 0.2, and the ternary material obtained has a stable crystal structure and a smooth lithium ion deintercalation channel, and has good rate performance.

[0027] In the present disclosure, some preferred embodiments, the half-peak width FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of (65±0.5)° ranges from 0.1 to 0.2.

[0028] Specifically, the half-peak width FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of (65±0.5)° refers to the value of the half-peak width of the (110) diffraction peak at the position of the half-peak height of the (110) diffraction peak in the X-ray diffraction spectrum, which is parallel to the horizontal axis of the diffraction angle 2θ. The FWHM(110) ranges from 0.1 to 0.2, and the ternary material obtained has a stable crystal structure and a smooth lithium ion deintercalation channel, and has good rate performance.

[0029] In the present disclosure, some preferred embodiments, the ternary material has an α-NaFeO2 layered structure.

[0030] It can be 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 a scanning rate of 2-5° / min within 3°-90°.

[0031] In the present disclosure, some preferred embodiments, the particle size (D50) of the ternary material is 5-20 μm; preferably 8-15 μm. The particle size in this range can ensure that the ternary material has better compaction density.

[0032] In a second aspect, the present disclosure provides a preparation method of a ternary material, comprising the following steps: 1) mixing a first lithium source and a transition metal precursor to obtain a first mixture, and adding a first dopant to the first mixture to obtain a first doped mixture; wherein the transition metal precursor comprises nickel, cobalt and manganese elements; the molar ratio of the nickel, cobalt and manganese elements is (1-x-y):x:y, 0

[0033] The preparation method of the ternary material provided by the present disclosure has the following effects compared with the prior art: first, the step-by-step lithium mixing process makes the lithium source and the ternary material precursor mixture more uniform, so that lithium ions are orderly embedded in the high-nickel ternary precursor lattice, and the mixing of lithium and nickel is alleviated; second, the step-by-step sintering process can adjust the sintering conditions multiple times, improve the negative effects of continuous high temperature on the lithium-nickel mixing of the ternary material, and ensure the consistency of the crystallinity inside and outside the ternary material, which is more conducive to the formation of ternary materials with stable and uniform structure; third, the doping process stabilizes the crystal structure of the ternary material and improves the cycle performance.

[0034] Specifically, the transition metal precursor is suitable for preparing ternary polycrystalline particles.

[0035] In some preferred embodiments of the present disclosure, the D50 of the transition metal precursor is between about 8 μm and 15 μm, and the transition metal precursor has a large secondary pellet appearance, with fine primary particles. The appearance of the secondary pellets can be inherited by the ternary polycrystalline particles after sintering.

[0036] In some preferred embodiments of the present disclosure, the nickel-cobalt-manganese precursor comprises at least one of a hydroxide precursor or a carbonate precursor.

[0037] 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 comprises one or more of lithium hydroxide, lithium nitrate, lithium carbonate, lithium acetate, lithium chloride, lithium fluoride, and lithium iodide.

[0038] In some preferred embodiments of the present disclosure, the first dopant, the second dopant, and the third dopant can be the same or different. The above dopants are compounds containing dopant elements. The dopant 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 the dopant element comprises 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 dopant elements have a radius similar to that of the transition metal ion and have a strong binding energy with oxygen, so that the crystal structure of the ternary material is more stable, the lattice order is higher, and the degree of lithium-nickel mixing of the high-nickel ternary material is reduced.

[0039] In some preferred embodiments of the present disclosure, the molar ratio of lithium elements in the lithium compound to M elements in the dopant is 1:(0.001-0.05); wherein the dopant comprises the first dopant, the second dopant, and the third dopant. By controlling the molar ratio of lithium to dopant elements within the above range, the effectiveness of element doping can be improved. Appropriate element doping can reduce the degree of nickel ion mixing of the material, improve the stability of the crystal surface structure, effectively inhibit the lattice distortion generated by the ternary material during charging and discharging, make the lithium ion more quickly deintercalate during the cycle process, and thus improve the structural stability and rate performance of the material.

[0040] In some preferred embodiments of the present disclosure, the first sintering comprises: performing the first sintering in an oxygen-containing atmosphere, the first sintering temperature is 600-800℃, the first sintering time is 12-24h, and the first sintering is followed by first cooling. The first cooling temperature is 20-30℃, and the cooling method is quenching, and the first sintering product after sintering is directly transferred to room temperature. The first sintering operation of the transition metal precursor helps to form ternary materials with good crystallinity, carbonize the polymer coating layer of the transition metal precursor, improve the true density of the material, and adjust the specific surface area of the material. The first cooling operation after the first sintering is performed to control the grain size of the intermediate product, so that the material grain is quickly and stably fixed at a fixed size, which can ensure the rapid crystallization of the ternary material, avoid the generation of other impurities, and improve the order of the layered structure of the ternary material.

[0041] In some preferred embodiments of the present disclosure, the second sintering comprises: after the first cooling, performing the second sintering in a pure oxygen atmosphere, the second sintering temperature being 300-600 DEG C, the second sintering time being 10-20 h, and after the second sintering, performing the second cooling. The second cooling temperature is 20-30 DEG C, and the cooling mode is quenching, and the sintered second sintering product is directly transferred to room temperature. Specifically, the pure oxygen atmosphere refers to a space filled with pure oxygen, and the second sintering is performed in the space filled with pure oxygen. The first sintering and the second sintering have the same effect, both of which are conducive to forming a ternary material with good crystallinity and improving the density of the ternary material. The first cooling and the second cooling also have the same effect, and the purpose is to control the grain size of the intermediate product, so that the ternary material grain is quickly and stably fixed at a fixed size, increase the compaction density of the ternary material when the electrode plate is prepared, and also ensure the rapid crystallization of the ternary material, avoid the generation of other impurities, and improve the order of the layered structure of the ternary material.

[0042] In some preferred embodiments of the present disclosure, the third sintering comprises: after the second cooling, performing the third sintering in a pure oxygen atmosphere, the third sintering temperature being 200-400 DEG C, the third sintering time being 5-10 h, and after the third sintering, performing the third cooling. The third cooling temperature is 20-30 DEG C, and the cooling mode is quenching, and the sintered third sintering product is directly transferred to room temperature.

[0043] It can be understood that the first sintering, the second sintering, and the third sintering are selected from one of a tube furnace, a box furnace, a fluidized bed, a rotary kiln, a microwave oven, and a tunnel furnace.

[0044] The three sintering methods make the crystallinity of the ternary material high, and the three cooling methods control the grain size of the intermediate product, so that the ternary material grain is stably fixed in a suitable size range, which is conducive to improving the compaction density of the ternary material, and also avoids the generation of other impurities and improves the order of the layered structure of the ternary material. The three sintering and cooling methods save the sintering equipment cooling time, shorten the process time, and are also conducive to obtaining a ternary material with a highly ordered layered structure, so that the ternary material has a high specific capacity.

[0045] In the three sintering processes, the sintering temperature is gradually reduced, and the sintering time is gradually reduced, showing a gradient sintering trend, which can ensure that the sites of lithium ion embedded in the transition metal precursor are more uniform. In the first sintering, the lithium content in the transition metal precursor is low, and high temperature is conducive to the rapid penetration of lithium ions. In the second sintering and the third sintering, as the lithium ion embedding amount increases, the repulsive force between atoms increases, and the lithium ion embedding difficulty increases. At this time, if the high-temperature sintering is continued, lithium-nickel mixing is easily caused. Therefore, the sintering temperature and the sintering time are gradually reduced in sequence to alleviate the lithium-nickel mixing.

[0046] In some preferred embodiments of the present disclosure, the heating rate of the first sintering is ≤ the heating rate of the second sintering ≤ the heating rate of the third sintering.

[0047] In the third sintering process, the heating rate is increased in turn, showing a gradient rising trend, which can ensure that the sites in which lithium ions are embedded in the ternary material precursor are more uniform; in the first sintering, slow heating ensures that the transition metal precursor is more stable in the transition to the ternary material crystal phase, avoiding lattice distortion. This process is also the process of embedding lithium ions in the crystal phase, and slow heating is beneficial to reducing the understanding of the mixed arrangement; in the second sintering and the third sintering, the heating rate is increased in turn, which is beneficial to increasing the stability of the ternary material crystal phase and saving sintering time.

[0048] In some preferred embodiments of the present disclosure, the heating rate of the first sintering is 2-5 ℃ / min.

[0049] In some preferred embodiments of the present disclosure, the heating rate of the second sintering is 5-10 ℃ / min.

[0050] In some preferred embodiments of the present disclosure, the heating rate of the third sintering is 10-20 ℃ / min. Satisfying the above heating rate, the performance of the ternary material obtained is more optimal.

[0051] In some preferred embodiments of the present disclosure, in step 1), a gelling agent can also be added to the first mixture. The order of adding the gelling agent and the dopant is not limited; the gelling agent can be added first, mixed with the first mixture, and then the dopant is added; or the dopant can be added first, mixed with the first mixture, and then the gelling agent is added; or the gelling agent and the dopant can be added at the same time and mixed with the first product.

[0052] 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%; the solvent comprises at least one of anhydrous ethanol or deionized water. The mass percentage of the solvent in the gelling agent in the above range can effectively disperse the lithium source, so that the lithium ions are uniformly dispersed on the surface of the transition metal precursor, facilitating lithiation.

[0053] In some preferred embodiments of the present disclosure, the mass percentage of the complexing agent in the gelling agent is 0.2wt%-2wt%; the complexing agent comprises sodium dodecyl sulfate (SDS). The complexing agent is helpful for the combination of the gelling agent and the lithium source, and the mass percentage of the complexing agent in the above range is helpful for the dispersion of the lithium source in the gelling agent, facilitating the formation of more stable ternary materials.

[0054] In some preferred embodiments of the present disclosure, the volume ratio of the polymer monomer to the solvent is (0.1-0.4):1; the polymer monomer comprises at least one of methyl methacrylate, styrene or acrylonitrile; and the polymer monomer is preferably methyl methacrylate. The polymer monomer is a precursor of the gel, and by controlling the volume ratio of the polymer monomer to the solvent within the above range, a gel with better coating performance is formed, which facilitates the improvement of the crystallinity after lithiation. In the mixing process of methyl methacrylate, the methyl methacrylate is polymerized into polymethyl methacrylate, which has higher dispersibility for the lithium source and better surface combination with the metal precursor. The carbon residue content of the finished product after sintering of the polymethyl methacrylate is in the range of 0.1 wt% to 3 wt%. The carbon residue content in this range is beneficial to further improving the rate performance.

[0055] In some preferred embodiments of the present disclosure, during the process of obtaining the gel particles by adding the gelling agent and the optional dopant into the first mixture, appropriate heating treatment can be performed, and the heating temperature is 40-80°C. Within this temperature range, the polymerization reaction is facilitated.

[0056] In a third aspect, the present disclosure provides a positive electrode sheet comprising the ternary material or the ternary material prepared by the preparation method of the ternary material.

[0057] The positive electrode sheet prepared by using the ternary material has high energy density and cycle life when applied to a battery.

[0058] In some preferred embodiments of the present disclosure, the compaction density of the positive electrode sheet is 3 g / cm 3 - 3.7 g / cm 3 .

[0059] The positive electrode sheet prepared by using the ternary material prepared by the present disclosure has a relatively complete layered structure and high compaction density, and can improve the energy density and cycle life of the battery when applied to the battery.

[0060] In a fourth aspect, the present disclosure provides a positive electrode sheet comprising a ternary material, wherein the ternary material has a chemical formula of LiNi 1-x-y Co x Mn y M a O2, wherein 0 FWHM (108) is the half-peak width of the (108) diffraction peak at a diffraction angle 2θ = (64±0.5)°; and FWHM (110) is the half-peak width of the (110) diffraction peak at a diffraction angle 2θ = (65±0.5)°.

[0061] In a fifth aspect, the present disclosure provides a lithium ion battery comprising the positive electrode sheet described above. The lithium ion battery using the present disclosure has a higher energy density and cycle life.

[0062] The lithium ion battery described above further comprises a negative electrode sheet, a diaphragm and an electrolyte. The negative electrode sheet comprises a current collector and a negative active material layer coated on at least one side of the current collector; the negative active material layer comprises a negative active material, a conductive agent and a binder.

[0063] The negative active material comprises a carbon-based material; the carbon-based material comprises one or more of artificial graphite, natural graphite, hard carbon material or soft carbon material.

[0064] The negative active material further comprises one or more of a silicon-based material, a tin-based material or a lithium titanate material. The silicon-based material can be a combination of one or more of elemental silicon, silicon oxide (SiO x , 0 x , 0 12 , 0

[0065] The binder can be a combination of one or more of Styrene Butadiene Rubber (SBR), Carboxymethyl Cellulose (CMC), Polyacrylic Acid (PAA), Polyacrylic Ethylene Acrylic Acid (PEAA), sodium alginate, carboxymethyl chitosan, Polyacrylonitrile (PAN) and Polyvinyl alcohol (PVA).

[0066] The current collector can be any one of a copper foil, a carbon-coated copper foil, a polymer-coated copper foil, a carbon cloth, a carbon nanotube film or a carbon paper.

[0067] The diaphragm can be a composite film of one or more of polyethylene, polypropylene and polyvinylidene fluoride.

[0068] The electrolyte is an organic solvent in which carrier ions are dissolved. The present disclosure does not limit the electrolyte, which can be self-adjusted according to actual conditions.

[0069] In a sixth aspect, the present disclosure provides a power consuming device comprising the lithium ion battery described above.

[0070] The power consuming device prepared using the lithium ion battery of the present disclosure can have higher market competitiveness.

[0071] In some embodiments of the present disclosure, the power consuming device includes, but is not limited to, a mobile phone, a notebook computer, a tablet computer, a wearable electronic device such as a smart watch, an electronic cigarette, and a new energy vehicle, an electric moped, and the like.

[0072] The present disclosure is further described in detail by the following examples.

[0073] Example 1

[0074] This example is used to illustrate the ternary material and the preparation method thereof disclosed in the present disclosure, which comprises the following steps:

[0075] 1) using Ni 0.90 Co 0.05 Mn 0.05 hydroxide precursor, using LiOH as the lithium source, first adding lithium hydroxide according to the ratio of lithium: transition metal elements = 0.4 and mixing to obtain a first mixed product; continue to add titanium dioxide powder (1500 ppm calculated based on the molar content of titanium element), zirconium oxide powder (2500 ppm calculated based on the molar content of zirconium element), tantalum pentoxide (1000 ppm calculated based on the molar content of tantalum element), and yttrium oxide powder (1000 ppm of additional content calculated based on the molar content of yttrium element) in the first mixed product, and mix at high speed for 8 hours; then pour into a ball mill and use anhydrous ethanol for ball milling and mixing for 8 hours; then add 0.4wt% sodium dodecyl sulfate, 30wt% H2O, and methyl methacrylate with a water volume ratio of 0.25 to the mixture, and stir for 1 hour to obtain a gel-like wrapped mixture of the precursor, lithium salt, and additives; heat the above mixture to 80℃ and keep for 1 hour, and collect the gel particles;

[0076] 2) then mix the gel particles again with LiOH according to the ratio of lithium: transition metal elements = 0.63 at high speed, and then perform a first sintering under an oxygen atmosphere, with a heating rate of 3℃ / min, a sintering temperature of 700℃, and a sintering time of 15 hours, and then sieve to obtain a first sintered product;

[0077] 3) mix the first sintered product with aluminum oxide powder (1500 ppm calculated based on the molar content of aluminum element) and perform a second sintering; the heating rate is 8℃ / min, the sintering temperature is 500℃, the sintering time is 12 hours, and the oxygen atmosphere is used to obtain a second sintered product;

[0078] 4) The second sintered product is mixed with boric acid (1000 ppm based on the molar content of boron element) and tungstic acid powder (1000 ppm based on the molar content of tungsten element), and is sintered for the third time, with a heating rate of 15°C / min, sintered at 350°C for 8h in oxygen atmosphere, to obtain the final ternary material.

[0079] wherein Ni 0.90 Co 0.05 Mn 0.05 The D50 of the hydroxide precursor of Ni Figure 1 and Figure 2 is 11 μm, and its SEMs of different magnifications are shown in Figure 1 ) Ni 0.90 Co 0.05 Mn 0.05 is a secondary spherical particle made of primary particles; in the high magnification SEM Figure 2 ) the primary particles are relatively elongated. The D50 of the final ternary material (LiNi 0.90 Co 0.05 Mn 0.05 O2) is 11 μm, and its SEM is shown in Figure 3 , LiNi 0.90 Co 0.05 Mn 0.05 MO2 is a secondary spherical particle made of primary particles.

[0080] The final ternary material is subjected to XRD test, using a copper target X-ray generator, scanning at 10-80° with a scanning rate of 3° / min, and the XRD spectrum is analyzed based on the peak positions and half-peak widths of the (108) diffraction peak and the (110) diffraction peak, and the data are listed in Table 1.

[0081] Example 2

[0082] The difference between Example 2 and Example 1 is that no titanium dioxide and tantalum pentoxide are added in the sintering of step 1).

[0083] Example 3

[0084] The difference between Example 3 and Example 1 is that no aluminum oxide is added in step 2).

[0085] Example 4

[0086] The difference between Example 4 and Example 1 is that no tungstic acid is added in step 4).

[0087] Example 5

[0088] Example 5 differs from Example 1 in that no tantalum pentoxide and yttrium oxide powder is added in the sintering of step 1); no aluminum oxide is added in step 2); and no tungstic acid is added in step 4).

[0089] Example 6

[0090] Example 6 differs from Example 5 in that, unlike Example 1, a Ni 0.88 Co 0.06 Mn 0.06 precursor in a ratio of 1 : 1 : 1 is used, the first sintering temperature is 750°C, 10h; and the second sintering temperature is 600°C, 8h.

[0091] Example 7

[0092] Example 7 differs from Example 5 in that a Ni 0.83 Co 0.12 Mn 0.05 precursor in a ratio of 1 : 1 : 1 is used, the first sintering temperature is 820°C, 14h; and the second sintering temperature is 660°C, 8h.

[0093] Example 8

[0094] Example 8 differs from Example 5 in that, in step 1), lithium hydroxide is added in a ratio of lithium: transition metal elements = 0.6; and in step 2), lithium hydroxide is added in a ratio of lithium: transition metal elements = 0.46.

[0095] Example 9

[0096] Example 9 differs from Example 5 in that, in step 1), lithium hydroxide is added in a ratio of lithium: transition metal elements = 0.9; and in step 2), lithium hydroxide is added in a ratio of lithium: transition metal elements = 0.15.

[0097] Example 10

[0098] Example 10 differs from Example 5 in that the same heating rate is used for the three sintering processes, which is 10°C / min.

[0099] Example 11

[0100] Example 11 differs from Example 5 in that the second sintering temperature is higher than the first sintering temperature, which is 750°C.

[0101] Comparative Example 1

[0102] Comparative Example 1 differs from Example 1 in that no dopant is added.

[0103] Comparative Example 2

[0104] Comparative Example 2 differs from Example 1 in that the lithium source is not added in stages, and lithium hydroxide is added in the first mixing process in a ratio of lithium: transition metal elements = 1.05.

[0105] Comparative Example 3

[0106] Comparative Example 3 differs from Example 6 in that the sintering is not carried out in stages as in Example 6, and a one-stage sintering is used, with a sintering temperature of 800°C, 33h

[0107] Comparative Example 4

[0108] Comparative Example 4 differs from Example 6 in that

[0109] Ni 0.78 Mn 0.22 the precursors are mixed in the above ratio, the first sintering temperature is 750°C, 14h; the second sintering temperature is 600°C, 8h; the third sintering temperature is 300°C, 4h; the gel coating treatment, the lithium addition in stages and the doping treatment in Example 1 are not carried out; and lithium hydroxide is added in a ratio of lithium: transition metal elements = 1.05.

[0110] The carbon residue of the ternary material prepared in Examples 1-11 and Comparative Examples 1-4 above is tested using a CS analyzer to obtain carbon residue data.

[0111] The FWHM (108), FWHM (110), 2θ (108) and 2θ (110) data in the XRD spectrum obtained after XRD testing of the ternary material prepared in Examples 1-11 and Comparative Examples 1-4 above are recorded in Table 1. The XRD half-peak width and peak position data are obtained from the processing software MDI Jade 6 by analyzing the XRD raw test file, and the specific data are shown in Table 1.

[0112] Table 1: Partial data table of ternary materials of Examples 1-11 and Comparative Examples 1-4

[0113]

[0114]

[0115] The positive electrode sheet S containing the ternary materials of Examples 1, 6, Comparative Examples 1 and 3 is selected, and the FWHM (108), FWHM (110), 2θ (108) and 2θ (110) data in the XRD spectrum obtained after XRD testing of the positive electrode sheet are recorded in Table 2. The XRD half-peak width and peak position data are obtained from the processing software MDI Jade 6 by analyzing the XRD raw test file, and the specific data are shown in Table 2.

[0116] Table 2: Partial data table of positive electrode sheets

[0117]

[0118] Performance test:

[0119] The ternary material prepared from the above Examples 1-11 and Comparative Examples 1-4 was prepared into a positive electrode sheet, a battery, and the following tests were performed.

[0120] Specific capacity test: The above ternary material was blended with PVDF, SP in a ratio of 96:3:1 with NMP as the solvent for 2h to form a stable and uniform positive electrode slurry. The positive electrode slurry was coated on an aluminum foil using a coating machine, dried, and cold-pressed to obtain a positive electrode sheet with a compaction density of 3.6 g / cm 3 The specific capacity of the third discharge test was taken as the specific capacity of the ternary material.

[0121] The negative electrode slurry was prepared by adding 95wt% of the negative electrode active material graphite, 2wt% of the binder SBR, 2wt% of the conductive agent graphite, and 1wt% of the thickening agent CMC into deionized water. The negative electrode slurry was coated on a copper foil, dried, and cold-pressed to obtain a compaction density of 1.7 g / cm 3 .

[0122] Battery preparation: The above prepared positive electrode sheet and negative electrode sheet and separator were prepared into a bare cell according to the conventional preparation process, the bare cell was dried, injected with electrolyte, packaged, and finally made into a battery.

[0123] The negative electrode active material artificial graphite, conductive carbon black, thickening agent (CMC), and binder (SBR) were mixed in a ratio of 96:1:1:2, and the powder and deionized water were stirred into a negative electrode slurry using a homogenizer and uniformly coated on a copper foil to obtain a negative electrode sheet.

[0124] Room temperature cycle performance test: The formed cell was tested at room temperature 25°C, and the discharge capacity retention of the battery was recorded after 500 cycles at 0.5C / 0.5C.

[0125] DC internal resistance (DCIR) test: The formed cell was tested at high temperature 45°C, and the DCIR retention of the battery was recorded after 500 cycles at 1C / 1C.

[0126] Table 2 Performance data table of Examples 1-11 and Comparative Examples 1-4

[0127]

[0128] As can be seen from the data in Table 3, the ternary material provided by the embodiment of the present disclosure meets the structural characteristics required by the present disclosure, and the discharge capacity, cycle performance and DCIR of the obtained battery are relatively improved compared with the comparative examples.

[0129] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A ternary material, wherein, 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, 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 polycrystalline 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: 0.8 < <0.98; FWHM (108) is a half-peak width of the (108) diffraction peak at a diffraction angle 2θ = (64±0.5)°; and FWHM (110) is a half-peak width of the (110) diffraction peak at a diffraction angle 2θ = (65±0.5)°.

2. The ternary material of claim 1, wherein, LiNi 1-x-y Co x Mn y M a O2, wherein 0 < x < 0.1, 0 < y < 0.05, 0 < a < 0.05, and M is selected from one or more of Zr, Ti, Zn, Mg, Ta, V, Al, Y, W, and B.

3. The ternary material of claim 1, wherein, The (108) diffraction peak and the (110) diffraction peak satisfy the following relationship: 0.85 < (110) diffraction peak / (108) diffraction peak < 0.

95. <0.

95.

4. The ternary material of claim 1, wherein, In the X-ray diffraction spectrum of the ternary material, the half-peak width FWHM (108) of the (108) diffraction peak ranges from 0.1 to 0.2; and / or The half-peak width FWHM (110) of the (110) diffraction peak ranges from 0.1 to 0.

2.

5. A method of producing the ternary material of any one of claims 1-4, wherein, The method comprises the following steps: 1) mixing a first lithium source and a transition metal precursor to obtain a first mixture, adding a first dopant to the first mixture to obtain a first doped mixture; wherein the transition metal precursor comprises nickel, cobalt and manganese elements; the molar ratio of the nickel, cobalt and manganese elements is (1-x-y):x:y, 0 2) mixing the first doped mixture and a second lithium source to obtain a second mixture, and performing first sintering on the second mixture in an oxygen-containing atmosphere to obtain a primary sintered product; wherein the molar ratio of lithium elements in the second lithium source to the total amount of nickel, cobalt and manganese elements in the precursor is (0.35-0.75):1; 3) mixing the primary sintered product and an optional second dopant, and performing second sintering on the mixture in an oxygen-containing atmosphere to obtain a secondary sintered product; 4) mixing the secondary sintered product and an optional third dopant, and performing third sintering on the mixture in an oxygen-containing atmosphere to obtain the ternary material; wherein the first dopant, the second dopant and the third dopant comprise M elements, 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 M elements in the first dopant, the second dopant and the third dopant to the sum of the molar amounts of nickel, cobalt and manganese elements in the precursor is a:1, and 0 6. The method of producing a ternary material according to claim 5, wherein The first sintering comprises: performing first sintering in an oxygen-containing atmosphere, the first sintering temperature is 600-800°C, the first sintering time is 12-24h, and first cooling is performed after the first sintering is completed; and / or The second sintering comprises: performing second sintering in a pure oxygen atmosphere after the first cooling is completed, the second sintering temperature is 300-600°C, the second sintering time is 10-20h, and second cooling is performed after the second sintering is completed; and / or The third sintering comprises: performing third sintering in a pure oxygen atmosphere after the second cooling is completed, the third sintering temperature is 200-400°C, the third sintering time is 5-10h, and third cooling is performed after the third sintering is completed. The heating rate of the first sintering is less than the heating rate of the second sintering, and the heating rate of the second sintering is less than the heating rate of the third sintering.

7. The method of producing a ternary material according to claim 6, wherein The heating rate of the first sintering is 2-5 ℃ / min; and / or the heating rate of the second sintering is 5-10 ℃ / min; and / or the heating rate of the third sintering is 10-20 ℃ / min.

8. The method of producing a ternary material according to claim 5, wherein, The first mixture can further comprise a gelling agent; the gelling agent comprises a solvent, a complexing agent and a polymer monomer; wherein the mass percentage of the solvent is 10-50 wt% based on the total mass of the gelling agent; the mass percentage of the complexing agent is 0.2-2 wt%; and the volume ratio of the polymer monomer to the solvent is (0.1-0.4):

1.

9. A positive electrode sheet, wherein The ternary material according to any one of claims 1-4, or the ternary material prepared by the preparation method according to any one of claims 5-8.

10. A lithium-ion battery, characterized by, The positive electrode sheet according to claim 9.

11. An electrical device, characterized by The lithium ion battery according to claim 10.

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