Multinary positive electrode material, preparation method and application thereof

Abstract

The application relates to the field of lithium ion batteries, and discloses a multi-element positive electrode material and a preparation method and application thereof. The multi-element positive electrode material is filled with a metal oxide solid solution shown in formula I between primary particles, wherein the metal oxide solid solution is formed by strontium and oxides of at least one element selected from Ni, Co and Mn; SrMe ε O δ Formula I; wherein Me is at least one element selected from Ni, Co and Mn; epsilon is greater than 0, and delta is greater than 0. The multi-element positive electrode material is filled with a metal oxide solid solution formed by strontium and metal elements Me in the multi-element positive electrode material between primary particles, so that the multi-element positive electrode material has lower surface residual lithium carbonate, is stable in structure, and a battery made of the multi-element positive electrode material has good cycle performance and lower gas production.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, specifically to a multi-element cathode material, its preparation method, and its application. Background Technology

[0002] Currently, the main cathode materials for commercially available lithium-ion batteries include lithium cobalt oxide (LiCoO2), lithium spinel manganese oxide (Li2MnO4), lithium iron phosphate (LiFePO4), and ternary materials (LiNi). x Co y Mn 1-x-y O2, the first three materials have relatively low reversible capacity, while the reversible capacity of ternary materials can increase with the increase of Ni content. By adjusting the Ni content, materials that meet the requirements can be obtained. However, when the Ni content increases, especially in materials with x > 0.60, it is easy to react with CO2 and H2O in the air, generating alkaline impurities Li2CO3 and LiOH on the material surface. This leads to severe gas generation during storage and charge / discharge use, resulting in battery swelling and deterioration of cycle life.

[0003] To reduce the residual alkaline impurities Li2CO3 and LiOH on the surface of high-nickel and lithium-rich ternary materials, the current main methods are pure water washing or acid washing to achieve rapid separation of surface alkaline impurities from the material system. CN107925078A discloses the use of lithium carbonate aqueous solution to clean lithium-nickel composite oxide powder, thereby removing excessive lithium from the material, but the Li2CO3 content in the final prepared positive electrode active material is still as high as 0.4-1.5 wt%. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of battery swelling caused by high lithium carbonate content in the prior art, and to provide a multi-element cathode material, its preparation method and application. The primary particles of the multi-element cathode material are filled with strontium, which forms a metal oxide solid solution with the metal element Me in the multi-element cathode material. This enables the multi-element cathode material to have a low surface residual lithium carbonate and a stable structure. The battery made from it has good cycle performance and lower gas production.

[0005] To achieve the above objectives, the first aspect of the present invention provides a multi-element cathode material, characterized in that the primary particles of the multi-element cathode material are filled with strontium and an oxide of at least one element selected from Ni, Co and Mn to form a metal oxide solid solution of Formula I.

[0006] SrMe ε O δ Formula I;

[0007] Me is selected from at least one element among Ni, Co, and Mn; ε > 0, δ > 0.

[0008] A second aspect of the present invention provides a method for preparing a multi-element cathode material, characterized in that the preparation method includes the following steps:

[0009] (1) The precursor, lithium source, Sr-doped compound and G'-doped compound are mixed to obtain a mixture; the mixture is sintered, crushed and sieved in an oxygen-containing atmosphere to obtain a first sintered material.

[0010] (2) After mixing and washing the first sintering material with water, solid-liquid separation is performed to obtain a solid phase, and the solid phase is dried to obtain a dried material;

[0011] (3) The dried material is mixed with a coating agent containing G element, and then sintered for a second time to obtain a secondary sintered material; the secondary sintered material is sieved and iron is removed to obtain the multi-element cathode material;

[0012] The precursor has the composition shown in Formula III:

[0013] Ni a Co b Mn c (OH)2 formula III,

[0014] Where 0.10≤a≤1, 0≤b≤1, 0≤c≤1.

[0015] A third aspect of the present invention provides a multi-element cathode material prepared by the above-described preparation method.

[0016] The fourth aspect of this invention provides an application of the above-mentioned multi-element cathode material in a lithium-ion battery.

[0017] Through the above technical solutions, the multi-element cathode material, its preparation method, and its application provided by the present invention achieve the following beneficial effects:

[0018] The primary intergranular space of the multi-element cathode material of the present invention is filled with Sr, which forms a metal oxide solid solution with the metal element Me in the multi-element cathode material. This can improve the density of the cathode material, reduce the specific surface area, improve the structural stability of the cathode material, and suppress the precipitation of lithium in the internal lattice of the material during water washing. The purpose of efficiently reducing the Li2CO3 content in the material can be achieved through simple water washing, resulting in a low residual Li2CO3 content on the surface of the finished cathode material. This improves the cycle performance of the battery made from the multi-element cathode material and reduces gas generation during high-temperature storage.

[0019] Furthermore, the multi-element cathode material provided by this invention has higher particle strength and a more stable structure during cycling, resulting in better cycle life and gas generation performance of the battery made from this multi-element cathode material.

[0020] Furthermore, the preparation method of the multi-element cathode material provided by this invention is simple, has a higher Li2CO3 removal rate under the same water washing conditions, has low requirements for equipment control, and is relatively inexpensive, making it suitable for industrialization. Attached Figure Description

[0021] Figure 1 These are the XRD patterns of the cathode materials prepared in Example 3 and Comparative Example 1;

[0022] Figure 2 This is a SEM image of the cross-section of the cathode material obtained in Example 3;

[0023] Figure 3 This is a diagram showing the distribution of Sr elements within the cathode material obtained in Example 3. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] The first aspect of the present invention provides a multi-element cathode material, characterized in that the primary particles of the multi-element cathode material contain strontium oxide, and at least a portion of the strontium oxide forms a metal oxide solid solution of Formula I with the oxidation of at least one element selected from Ni, Co and Mn.

[0026] SrMe ε O δ Formula I;

[0027] Me is selected from at least one element among Ni, Co, and Mn; ε > 0, δ > 0.

[0028] In this invention, the multi-element cathode material is a nickel-cobalt-manganese multi-element cathode material.

[0029] The primary intergranular space of the multi-element cathode material provided by this invention is filled with Sr, which forms a metal oxide solid solution with the metal element Me in the multi-element cathode material. The Sr element and the Me transition metal element in the material bulk form a Sr-Me metal oxide solid solution (SrMe). ε O δIt fills the grain boundaries between primary particles and plays a role in sealing the grain boundary gaps and stabilizing the structure during the washing of multi-element cathode materials. This reduces the damage to the strength of the particle structure caused by the washing process, thereby improving the material strength and enhancing the battery's cycle life and safety performance such as gas generation.

[0030] In this invention, XRD characterization of the multi-component cathode material confirms the presence of a metal oxide solid solution, such as... Figure 1 As shown, the XRD spectra of the multi-element cathode material A3 and the multi-element cathode material D1, obtained under the same XRD measurement conditions, are compared from... Figure 1 As can be seen from the XRD spectrum of the multi-element cathode material A3, characteristic peaks of metal oxide solid solution Sr2Ni2O5 appear at positions 28°-31° and 32°-34°, indicating that Sr and Me oxides form metal oxide solid solutions in the multi-element cathode material.

[0031] In one specific embodiment of the present invention, in Formula I, Me is at least one of Ni, Co and Mn; 0 < ε ≤ 4, 0 < δ ≤ 8.

[0032] In one specific embodiment of the present invention, the metal oxide solid solution is a metal oxide solid solution formed by strontium oxide and at least one nickel oxide selected from NiO, NiO2, and Ni2O3; or the metal oxide is a metal oxide solid solution formed by strontium oxide and at least one cobalt oxide selected from CoO, Co3O4, Co2O3, and CoO2; or the metal oxide solid solution is a metal oxide solid solution formed by strontium oxide and at least one manganese oxide selected from MnO, Mn3O4, Mn2O3, MnO2, Mn2O5, MnO3, and Mn2O7.

[0033] According to the present invention, based on the total weight of the multi-element cathode material, the content of the metal oxide solid solution is 0.01-0.60 wt% calculated by Sr element.

[0034] In this invention, when the content of the metal oxide solid solution meets the above-mentioned range, since it fills the intergranular gaps inside the material, it can reduce the specific surface area, improve the structural stability of the cathode material, and suppress the precipitation of lithium in the lattice inside the material during water washing. The content of Li2CO3 in the cathode material can be efficiently reduced by simple water washing. When this cathode material is used in lithium-ion batteries, it can significantly improve the cycle performance of lithium-ion batteries and reduce gas generation during high-temperature storage.

[0035] Furthermore, based on the total weight of the multi-element cathode material, the content of the metal oxide solid solution, calculated in terms of Sr element, is 0.05-0.40 wt%.

[0036] According to the present invention, the multi-element cathode material has the composition shown in general formula II:

[0037] Li 1+α Ni x Co y Mn z G' g G” k O2@βSrMe ε O δ Formula II

[0038] In Formula II, 0≤α≤0.2, 0.10≤x<1, 0≤y≤1, 0≤z≤1, 0≤g≤0.05, 0≤k≤0.05, x+y+z+g+k≤1, 0<β≤0.010, ε>0, δ>0; G' and G” are each independently selected from at least one element among Mo, Ca, Mg, Fe, Zr, Ti, Zn, Y, W, V, Nb, La, Al, Cr, F and B, and Me is selected from at least one element among Ni, Co and Mn.

[0039] In this invention, Sr fills the spaces between the primary particles of the multi-element cathode material, forming a metal oxide solid solution (SrMe) with the metal element Me in the multi-element cathode material. ε O δ This process can improve the density of the multi-element cathode material, reduce the specific surface area, improve the structural stability of the cathode material, suppress the precipitation of lithium in the internal lattice of the material during the water washing process, and achieve the goal of efficiently reducing the Li2CO3 content in the material through simple water washing. This results in a lower residual Li2CO3 content on the surface of the finished cathode material, thereby improving the cycle performance of the battery made from this multi-element cathode material and reducing gas generation during high-temperature storage.

[0040] In this invention, the inventors discovered that residual lithium in multi-element cathode materials exists primarily in the forms of Li₂CO₃ and LiOH. LiOH can react with H₂O and CO₂ in the air to ultimately form Li₂CO₃, and lithium from the internal lattice of the material also precipitates to the surface, resulting in a significant portion of the residual lithium existing as Li₂CO₃. Both of these lithium compounds have a certain degree of solubility in water, with LiOH being more readily soluble and easier to remove through washing.

[0041] Further, in Formula II, 0 < α ≤ 0.2, 0.30 ≤ x ≤ 1, 0 ≤ y ≤ 0.30, 0 ≤ z ≤ 0.80, 0.005 ≤ g ≤ 0.03, 0.005 ≤ k ≤ 0.03, x + y + z + g + k ≤ 1, 0 < β ≤ 0.03, 0 < ε ≤ 4, 0 < δ ≤ 8; G' and G” are each independently selected from at least one element among Mo, Ca, Mg, Fe, Zr, Ti, Zn, Y, W, V, Nb, La, Al, Cr, F and B, and Me is selected from at least one element among Ni, Co and Mn.

[0042] In this invention, G' and G” can be the same or different. When G' and G” are the same element, the content of G' and G” in the multi-element cathode material is the sum of the two, that is, in formula II, 0≤g+k≤0.1, preferably, 0≤g+k≤0.06.

[0043] According to the present invention, the specific surface area (SSA) of the multi-element cathode material is 0.2-2 m². 2 / g.

[0044] Furthermore, the specific surface area (SSA) of the multi-element cathode material is 0.2-1.2 m². 2 / g.

[0045] According to the present invention, the residual Li2CO3 content on the surface of the multi-element cathode material is ≤0.15wt%.

[0046] Furthermore, the residual Li2CO3 content on the surface of the multi-element cathode material is ≤0.12wt%.

[0047] According to the present invention, the maximum crushing pressure of the multi-element cathode material is 100-200 MPa.

[0048] Furthermore, the maximum crushing pressure of the multi-element cathode material is 150-200 MPa.

[0049] A second aspect of the present invention provides a method for preparing a multi-element cathode material, characterized in that the preparation method includes the following steps:

[0050] (1) The precursor, lithium source, Sr-doped compound and G'-doped compound are mixed to obtain a mixture; the mixture is sintered, crushed and sieved in an oxygen-containing atmosphere to obtain a first sintered material.

[0051] (2) After mixing and washing the first sintering material with water, solid-liquid separation is performed to obtain a solid phase, and the solid phase is dried to obtain a dried material;

[0052] (3) The dried material is mixed with a coating agent containing G element, and then sintered for a second time to obtain a secondary sintered material; the secondary sintered material is sieved and iron is removed to obtain the multi-element cathode material;

[0053] The precursor has the composition shown in Formula III:

[0054] Ni a Co b Mn c (OH)2 formula III,

[0055] Where 0.1≤a≤1, 0≤b≤1, 0≤c≤1.

[0056] In this invention, the preparation method involves mixing a Sr-doped compound with a precursor, a lithium source, and optionally a G-doped compound, followed by a first sintering. This introduces Sr into the cathode material, thereby forming an Sr-Me metal oxide solid solution between the primary grain boundaries of the cathode material. This significantly improves the density of the multi-element cathode material, reduces its specific surface area, enhances its structural stability, and suppresses the precipitation of lithium lattice within the material during water washing. Simple water washing effectively reduces the Li2CO3 content in the material, resulting in a lower residual Li2CO3 content on the surface of the finished cathode material. This improves the cycle performance of the battery made from this multi-element cathode material and reduces gas generation during high-temperature storage.

[0057] Furthermore, the preparation method provided by this invention is simple, has a higher Li2CO3 removal rate under the same water washing conditions, requires less equipment control, and is relatively inexpensive, making it suitable for industrialization.

[0058] According to the present invention, in step (1), the lithium source is selected from lithium hydroxide and / or lithium carbonate.

[0059] According to the present invention, the compound containing the doped element Sr is selected from at least one of Sr oxides, Sr hydroxides, Sr salts, and Sr organic compounds. Specifically, the compound containing the doped element Sr is selected from SrO, Sr(OH)2, SrCO3, etc.

[0060] According to the present invention, the compound containing the dopant element G' is selected from compounds that provide at least one element selected from Mo, Ca, Mg, Fe, Zr, Ti, Zn, Y, W, V, Nb, La, Al, Cr, F and B.

[0061] Furthermore, the compound containing the dopant element G' is selected from at least one of the following: oxides of G', hydroxides of G', salts of G', and organic compounds of G'.

[0062] According to the present invention, the amounts of the precursor and the lithium source are such that 1≤n(Li) / [n(Ni)+n(Co)+n(Mn)]≤1.60.

[0063] According to the present invention, the amount of the compound containing the doped element Sr is such that, based on the content of the multi-element cathode material, the content of the Sr element is 100-10000 ppm.

[0064] In this invention, when the content of Sr element meets the above range, the solid solution oxide generated by the sintering reaction of the mixture can fully fill the grain boundary gaps, which can stabilize the particle structure, so that the multi-element cathode material obtained thereby has the characteristics of low lithium carbonate content, high strength and small specific surface area.

[0065] Furthermore, the amount of the compound containing the doped element Sr is such that, based on the content of the multi-element cathode material, the content of the Sr element is 100-5000 ppm.

[0066] According to the present invention, the amount of the compound containing the doped element G' is such that, based on the content of the multi-element cathode material, the content of the G' element is 0-10000 ppm.

[0067] In this invention, when the content of element G' meets the above-mentioned range, the doping element G' can stabilize the structure of the multi-element cathode material, increase the interlayer spacing, and facilitate the insertion and extraction of lithium ions, thereby improving the charging capacity and cycle life of the lithium-ion battery containing the cathode material.

[0068] Furthermore, the amount of the compound containing dopant element G' is such that, based on the content of the precursor, the content of element G' is 100-6000 ppm.

[0069] According to the present invention, the oxygen-containing atmosphere is selected from oxygen and / or air.

[0070] Furthermore, in Formula III, when a ≥ 0.60, and the oxygen concentration in the oxygen-containing atmosphere is ≥ 90 vol%, the resulting multi-element cathode material exhibits Ni... 2+ It has the advantages of low content and good crystallinity.

[0071] According to the present invention, the conditions for the first sintering include: heating from 20-30°C to 600-1000°C at a heating rate of 0.5-5°C / min, and holding at that temperature for 5-25 hours.

[0072] Furthermore, the conditions for the first sintering include: heating from 20-30℃ to 650-950℃ at a heating rate of 0.5-3℃ / min, and holding at that temperature for 5-15 hours.

[0073] According to the present invention, in step (2), the solid-liquid ratio of the first sintering material to the water is 0.5-4 g / mL.

[0074] Furthermore, the solid-liquid ratio of the first sintering material to the water is 1-3 g / mL.

[0075] According to the present invention, the washing conditions include: a washing temperature of 5-30°C and a washing time of 0.5-30 min.

[0076] Furthermore, the washing conditions include: a washing temperature of 10-25℃ and a washing time of 1-10 minutes;

[0077] According to the present invention, the drying is vacuum drying.

[0078] According to the present invention, in step (3), the amount of the coating agent containing the G” element is such that, based on the total weight of the multi-element cathode material, the content of the G” element is 0-10000ppm.

[0079] Furthermore, the amount of the coating agent containing "G" element is such that, based on the total weight of the multi-element cathode material, the content of "G" element is 100-5000 ppm.

[0080] According to the present invention, the conditions for the second sintering include: heating from 20-30°C to 200-800°C at a heating rate of 1-10°C / min, and holding at that temperature for 4-20 hours.

[0081] In this invention, there is no particular limitation on the atmosphere for the second sintering; it can be oxygen or dry air.

[0082] Furthermore, the conditions for the second sintering include: heating from 23-28°C to 250-700°C at a heating rate of 2-6°C / min, and holding at that temperature for 5-15 hours.

[0083] A third aspect of the present invention provides a multi-element cathode material prepared by the above-described preparation method.

[0084] In this invention, the primary grain boundaries of the multi-element cathode material are filled with Sr and an oxide of at least one element selected from Ni, Co and Mn to form a metal oxide solid solution of Formula I.

[0085] SrMe ε O δ Formula I;

[0086] Me is selected from at least one element among Ni, Co, and Mn; ε > 0, δ > 0.

[0087] Furthermore, in Equation I, 0 < ε ≤ 4, 0 < δ ≤ 8.

[0088] In this invention, based on the total weight of the multi-element cathode material, the content of the metal oxide solid solution, calculated by Sr element, is 0.01-0.60 wt%, preferably 0.05-0.40 wt%.

[0089] In this invention, the positive electrode material has the composition shown in general formula II:

[0090] Li 1+α Ni x Co y Mn z G' g G” k O2@βSrMe ε O δ Formula II

[0091] In Formula II, 0≤α≤0.2, 0.10≤x<1, 0≤y≤1, 0≤z≤1, 0≤g≤0.05, 0≤k≤0.05, x+y+z+g+k≤1, 0<β≤0.010, ε>0, δ>0, G' and G” are each independently selected from at least one element among Mo, Ca, Mg, Fe, Zr, Ti, Zn, Y, W, V, Nb, La, Al, Cr, F and B, and Me is selected from at least one element among Ni, Co and Mn.

[0092] Further, in Formula II, 0<α≤0.2, 0.10≤x<1, 0≤y≤0.30, 0≤z≤0.80, 0.005≤g≤0.030, 0.005≤k≤0.030, x+y+z+g+k≤1, 0<β≤0.005, 0<ε≤4, 0<δ≤8; G' and G” are each independently selected from at least one element among Mo, Ca, Mg, Fe, Zr, Ti, Zn, Y, W, V, Nb, La, Al, Cr, F and B, and Me is at least one element among Ni, Co and Mn.

[0093] In this invention, the SSA of the multi-element cathode material is 0.2-2m. 2 / g, preferably 0.2-1.2m 2 / g.

[0094] In this invention, the residual Li2CO3 content on the surface of the multi-element cathode material is ≤0.15wt%, preferably ≤0.12wt%.

[0095] Furthermore, the maximum crushing pressure of the multi-element cathode material is 100-200 MPa, preferably 150-200 MPa.

[0096] The fourth aspect of this invention provides an application of the above-mentioned multi-element cathode material in a lithium-ion battery.

[0097] The present invention will be described in detail below through embodiments. In the following embodiments,

[0098] The structural composition of the cathode material was determined by XRD and ICP.

[0099] The content of metal oxide solid solution in the cathode material was determined by XRD and ICP methods.

[0100] The residual alkali content on the surface of the cathode material was tested using potentiometric titration.

[0101] The maximum crushing pressure of the cathode material particles was measured using a micro-compression tester.

[0102] The specific surface area (SSA) of the cathode material was measured using the BET method.

[0103] The morphology of the cathode material was measured using SEM;

[0104] The distribution of Sr in the cathode material was measured using EDS.

[0105] The battery volume expansion rate was measured using the water displacement method.

[0106] The battery's 500-cycle 1C / 1C cycle retention rate was measured using the national standard method;

[0107] All raw materials used in the examples and comparative examples are commercially available products.

[0108] Example 1

[0109] (1) Ni 0.8 Co 0.1 Mn 0.1 The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 are mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04. Based on the total weight of the multi-element cathode material, the content of Al element is 5000ppm and the content of Sr element is 2000ppm. The mixture is sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering are: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere is 97vol%. Then, it is naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0110] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 1g / mL, the washing time is 3min, and the washing temperature is 20℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0111] (3) The dried material and Al2O3 were mixed evenly to obtain a mixture. The amount of Al2O3 was such that, based on the total weight of the multi-element cathode material, the Al element content was 1000 ppm. The mixture was sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 25℃ to 600℃ at a rate of 3℃ / min, sintering at 600℃ for 8 hours, and then cooling with the furnace to obtain the second sintered material. After cooling, the material was sieved to obtain the multi-element cathode material A1. XRD testing of cathode material A1 confirmed that Sr and Ni oxides formed a metal solid solution in cathode material A1. Specifically, the composition of cathode material A1 is: Li 1.04 Ni 0.782 Co 0.098 Mn 0.098 Al 0.021 O2@0.002SrNiO3.

[0112] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0113] Example 2:

[0114] (1) Ni 0.85 Co 0.08 Mn 0.07 The (OH)2 precursor, lithium hydroxide, nano-zirconia, and SrCO3 were mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.03. Based on the total weight of the multi-element cathode material, the Zr content was 2500ppm and the Sr content was 3500ppm. The mixture was subjected to a first sintering in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 730℃ at a rate of 2℃ / min, sintering at 730℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 97vol%. Then, it was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0115] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 2g / mL, the washing time is 3min, and the washing temperature is 15℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0116] (3) The dried material and B2O3 were mixed evenly to obtain a mixture. The amount of B2O3 was such that, based on the total weight of the multi-element cathode material, the content of element B was 1000 ppm. The mixture was sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 35℃ to 400℃ at a rate of 3℃ / min, sintering at 400℃ for 8 hours, and then cooling with the furnace. The second sintered material was then sieved to obtain multi-element cathode material A2. XRD testing of cathode material A2 confirmed that Sr and Ni oxides formed a metal solid solution in cathode material A2. Specifically, the composition of cathode material A2 is: Li 1.03 Ni 0.846 Co 0.080 Mn 0.070 Zr 0.003 B 0.001 O2@0.004SrNi 0.8 O 2.2 .

[0117] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.35 wt%.

[0118] Example 3

[0119] (1) Ni 0.95 Co 0.03 Mn 0.02 The precursor (OH)2, lithium hydroxide, nano-zirconia, and Sr(OH)2 were mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.05. Based on the total weight of the multi-element cathode material, the Zr content was 2500ppm and the Sr content was 5000ppm. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 700℃ at a rate of 1℃ / min, sintering at 700℃ for 8 hours, and the oxygen content in the atmosphere was 95vol%. Then, it was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0120] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 2g / mL, the washing time is 3min, and the washing temperature is 25℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0121] (3) The dried material and H3BO3 were mixed evenly to obtain a mixture. The amount of H3BO3 was such that, based on the total weight of the multi-element cathode material, the content of element B was 2000 ppm. The mixture was then subjected to a second sintering in an air atmosphere. The conditions for the second sintering were: heating from 30℃ to 320℃ at a rate of 3℃ / min, sintering at 320℃ for 8 hours, and then cooling with the furnace. The second sintered material was then sieved to obtain multi-element cathode material A3. XRD tests were performed on cathode material A3, and the results are as follows. Figure 1 As shown, from Figure 1 It can be seen that the cathode material A3 exhibits characteristic peaks at 28°-31° and 32°-34°, indicating that Sr and Ni oxides form a metal solid solution, Sr₂Ni₂O₅, in cathode material A3. Specifically, the composition of cathode material A3 is: Li 1.05 Ni 0.945 Co 0.030 Mn 0.020 Zr 0.003 B 0.002 O2@0.006SrNiO 2.5 .

[0122] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.50 wt%.

[0123] Figure 2 and Figure 3 These are SEM and EDS images of the A3 cross-section of the cathode material, respectively. Figure 2 and Figure 3 It can be seen that Sr and its metal oxide solid solutions (SrMe) ε O δ It is mainly distributed in the intergranular spaces of the material.

[0124] Example 4

[0125] (1) Ni 0.16 Co 0.16 Mn 0.68 The (OH)2 precursor, lithium carbonate, and SrCO3 were mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.50, and the Sr element content was 5000ppm based on the total weight of the multi-element cathode material. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 850℃ at a rate of 1℃ / min, sintering at 850℃ for 10h, and the oxygen content in the oxygen-containing atmosphere was 21vol%. Then, it was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0126] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 1g / mL, the washing time is 10min, and the washing temperature is 10℃. Then the slurry is filtered, and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0127] (3) The dried material and WO3 were mixed evenly to obtain a mixture. The amount of WO3 was such that, based on the total weight of the cathode material, the W element content was 2000 ppm. The mixture was then sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 22℃ to 500℃ at a rate of 3℃ / min, sintering at 500℃ for 8 hours, and then cooling with the furnace. The second sintered material was then sieved to obtain a multi-element cathode material A4. XRD testing of cathode material A4 confirmed that Sr and Mn oxides formed a metal solid solution in cathode material A4. The composition of cathode material A4 was: Li 1.20 Ni 0.129 Co 0.129 Mn 0.542 W 0.001 O2@0.005SrMnO3.

[0128] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.5 wt%.

[0129] Example 5

[0130] The cathode material A5 was prepared according to the method in Example 1, except that:

[0131] (1) Ni 0.8 Co 0.1 Mn 0.1 The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 were mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04. Based on the total weight of the multi-element cathode material, the content of Al element was 5000ppm and the content of Sr element was 6000ppm. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 97vol%. Then, it was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0132] Steps (2) and (3) are the same as in Example 1. A multi-element cathode material A5 is obtained. XRD analysis of cathode material A5 confirms that Sr and Ni oxides form a metal solid solution in cathode material A5. Specifically, the composition of cathode material A5 is: Li 1.04 Ni 0.781 Co0.099 Mn 0.099 Al 0.022 O2@0.007SrNiO3.

[0133] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.60 wt%.

[0134] Example 6

[0135] The cathode material A6 was prepared according to the method in Example 1, with the following difference:

[0136] (1) Ni 0.8 Co 0.1 Mn 0.1 The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 were mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04. Based on the total weight of the multi-element cathode material, the content of Al element was 5000ppm and the content of Sr element was 12000ppm. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 97vol%. Then, it was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0137] Steps (2) and (3) are the same as in Example 1, yielding a multi-element cathode material A6. XRD analysis of cathode material A1 confirmed that Sr and Ni oxides form a metal solid solution in cathode material A1. Specifically, the composition of cathode material A6 is: Li 1.04 Ni 0.780 Co 0.099 Mn 0.099 Al 0.022 O2@0.014SrNiO3.

[0138] Of which, the content of metal oxide solid solution, calculated by Sr element, is 1.2 wt%.

[0139] Example 7

[0140] The cathode material A7 was prepared according to the method in Example 1, except that:

[0141] (1) Ni 0.8 Co 0.1 Mn 0.1The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 are mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04. Based on the total weight of the multi-element cathode material, the content of Al element is 5000ppm and the content of Sr element is 2000ppm. The mixture is sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering are: heating from room temperature to 760℃ at a rate of 5℃ / min, sintering at 760℃ for 18h, and the oxygen content in the oxygen-containing atmosphere is 97vol%. Then, it is naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0142] Step (2) is the same as in Example 1;

[0143] (3) The dried material and Al2O3 were mixed evenly to obtain a mixture. The amount of Al2O3 was such that, based on the total weight of the cathode material, the Al content was 1000 ppm. The mixture was then sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 25°C to 400°C at a rate of 3°C / min, sintering at 400°C for 8 hours, and then cooling with the furnace to obtain the second sintered material. After cooling, the material was sieved to obtain the multi-element cathode material A7. XRD testing of cathode material A7 confirmed that Sr and Ni oxides formed a metal solid solution in cathode material A7. Specifically, the composition of cathode material A7 is: Li 1.0 4Ni 0.781 Co 0.099 Mn 0.099 Al 0.021 O2@0.002SrNi4O8.

[0144] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0145] Example 8

[0146] The cathode material A8 was prepared according to the method in Example 1, except that:

[0147] (1) Ni 0.8 Co 0.1 Mn 0.1The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 are mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04. Based on the total weight of the multi-element cathode material, the content of Al element is 5000ppm and the content of Sr element is 2000ppm. The mixture is sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering are: heating from room temperature to 760℃ at a rate of 10℃ / min, sintering at 760℃ for 4 hours, and the oxygen content in the oxygen-containing atmosphere is 97vol%. Then, it is naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0148] Step (2) is the same as in Example 1;

[0149] (3) The dried material and Al2O3 were mixed evenly to obtain a mixture. The amount of Al2O3 was such that, based on the total weight of the cathode material, the Al element content was 1000 ppm. The mixture was then sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 25°C to 400°C at a rate of 3°C / min, sintering at 400°C for 8 hours, and then cooling with the furnace to obtain the second sintered material. After cooling, the material was sieved to obtain the multi-element cathode material A8. XRD testing of cathode material A8 confirmed that Sr and Ni oxides formed a metal solid solution in cathode material A8. Specifically, the composition of cathode material A8 is: Li 1.0 4Ni 0.782 Co 0.098 Mn 0.098 Al 0.021 O2@0.002SrNi 0.778 O 2.33 .

[0150] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0151] Example 9

[0152] The cathode material A9 was prepared according to the method in Example 1, with the following difference:

[0153] (1) Ni 0.8 Co 0.1 Mn 0.1The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 were mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04. Based on the total weight of the multi-element cathode material, the Al content was 5000ppm and the Sr content was 2000ppm. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 81vol%. Then, the mixture was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0154] Steps (2) and (3) are the same as in Example 1, yielding a multi-element cathode material A9. XRD analysis of cathode material A9 confirmed that Sr and Ni oxides form a metal solid solution in A9. Specifically, the composition of cathode material A9 is: Li... 1.04 Ni 0.782 Co 0.098 Mn 0.098 Al 0.021 O2@0.002SrNiO2.

[0155] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0156] Example 10

[0157] The cathode material A10 was prepared according to the method in Example 1, except that:

[0158] Step (1) is the same as in Example 1;

[0159] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 0.5 g / mL, the washing time is 3 min, and the washing temperature is 20℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0160] Step (3) is the same as in Example 1, yielding a multi-element cathode material A10. XRD analysis of the cathode material A10 confirmed that Sr and Ni oxides form a metal solid solution within it. Specifically, the composition of the cathode material A10 is: Li... 1.036 Ni 0.782 Co 0.098 Mn 0.098 Al 0.021 O2@0.002SrNiO3.

[0161] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0162] Example 11

[0163] The cathode material A11 was prepared according to the method in Example 1, except that:

[0164] Step (1) is the same as in Example 1;

[0165] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 0.2 g / mL, the washing time is 3 min, and the washing temperature is 20℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0166] Step (3) is the same as in Example 1, yielding a multi-element cathode material A11. XRD analysis of the cathode material A11 confirmed that Sr and Ni oxides form a metal solid solution within it. Specifically, the composition of the cathode material A11 is: Li... 1.029 Ni 0.782 Co 0.098 Mn 0.098 Al 0.021 O2@0.002SrNiO3.

[0167] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0168] Example 12

[0169] The cathode material A12 was prepared according to the method in Example 1, with the following difference:

[0170] Step (1) is the same as in Example 1;

[0171] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 1g / mL, the washing time is 20min, and the washing temperature is 30℃. Then the slurry is filtered, and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0172] Step (3) is the same as in Example 1, yielding a multi-element cathode material Al2. XRD analysis of the cathode material Al2 confirmed that Sr and Ni oxides form a metal solid solution in Al2. Specifically, the composition of the cathode material Al2 is: Li... 1.032 Ni 0.782 Co 0.098 Mn 0.098 Al 0.021 O2@0.002SrNiO3.

[0173] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0174] Example 13

[0175] The cathode material A13 was prepared according to the method in Example 1, with the following difference:

[0176] Step (1) is the same as in Example 1;

[0177] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 1g / mL, the washing time is 60min, and the washing temperature is 35℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0178] Step (3) is the same as in Example 1, yielding a multi-element cathode material A13. XRD analysis of the cathode material A13 confirmed that Sr and Ni oxides form a metal solid solution in the cathode material A13. Specifically, the composition of the cathode material A13 is: Li 1.025 Ni 0.782 Co 0.098 Mn 0.098 Al 0.021 O2@0.002SrNiO3.

[0179] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0180] Example 14

[0181] The cathode material A14 was prepared according to the method in Example 1, with the following difference:

[0182] (1) Ni 0.8 Co 0.1 Mn 0.1 The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 were mixed uniformly to obtain a mixture in which Li / Me (molar ratio, where Me is the sum of nickel, cobalt, and manganese) = 1.04. Based on the total weight of the multi-element cathode material, the Al content was 7500 ppm, and based on the total weight of the precursor, the Sr content was 2000 ppm. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 97 vol%. Then, the mixture was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0183] Steps (2) and (3) are the same as in Example 1; multi-element cathode material A14 is obtained.

[0184] XRD analysis of the cathode material Al4 confirmed that Sr and Ni oxides form a metal solid solution within Al4. Specifically, the composition of the cathode material Al4 is: Li 1.04 Ni 0.775 Co0.097 Mn 0.097 Al 0.030 O2@0.002SrNiO3.

[0185] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0186] Example 15

[0187] The cathode material A15 was prepared according to the method in Example 1, with the following difference:

[0188] In step (3), controlling the amount of G' is not within the scope of the claims.

[0189] (1) Ni 0.8 Co 0.1 Mn 0.1 The precursor (OH)2, lithium hydroxide, nano-alumina, and Sr(OH)2 were mixed uniformly to obtain a mixture in which Li / Me (molar ratio, where Me is the sum of nickel, cobalt, and manganese) = 1.04. Based on the total weight of the multi-element cathode material, the Al content was 12000 ppm, and based on the total weight of the precursor, the Sr content was 2000 ppm. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 97 vol%. Then, it was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0190] Steps (2) and (3) are the same as in Example 1; positive electrode material A15 is obtained.

[0191] XRD analysis of the cathode material A15 confirmed that Sr and Ni oxides form a metal solid solution within A15. Specifically, the composition of cathode material A15 is: Li 1.04 Ni 0.763 Co 0.096 Mn 0.096 Al 0.046 O2@0.002SrNiO3.

[0192] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0193] Example 16

[0194] The cathode material A16 was prepared according to the method in Example 1, with the following difference:

[0195] Steps (1) and (2) are the same as in Example 1;

[0196] (3) The dried material was directly subjected to a second sintering. The conditions for the second sintering were: heating from 25°C to 600°C at a rate of 3°C / min, sintering at 600°C for 8 hours, and then cooling in the furnace to obtain the second sintered material. After cooling, the material was sieved to obtain the multi-element cathode material A16. XRD testing of cathode material A16 confirmed that Sr and Ni oxides formed a metal solid solution in cathode material A16. Specifically, the composition of cathode material A16 is: Li 1.04 Ni 0.786 Co 0.098 Mn 0.098 Al 0.018 O2@0.002SrNiO3.

[0197] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0198] Example 17

[0199] The multi-element cathode material was prepared according to the method in Example 1, with the following difference:

[0200] (1) Ni 0.8 Co 0.1 Mn 0.1 The (OH)2 precursor, lithium hydroxide, and Sr(OH)2 were mixed uniformly to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04, and the Sr element content was 2000ppm based on the total weight of the multi-element cathode material. The mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 97vol%. Then, it was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0201] Step (2) is the same as in Example 1;

[0202] (3) The dried material was subjected to a second sintering in air atmosphere. The conditions for the second sintering were: heating from 25°C to 600°C at a rate of 3°C / min, maintaining the temperature at 600°C for 8 hours, and then cooling in the furnace to obtain the second sintered material. After cooling, the material was sieved to obtain the multi-element cathode material A17. XRD testing of cathode material A17 confirmed that Sr and Ni oxides formed a metal solid solution in cathode material A17. Specifically, the composition of cathode material A17 is: Li 1.04 Ni 0.800 Co 0.100 Mn 0.100 O2@0.002SrNiO3.

[0203] Of which, the content of metal oxide solid solution, calculated by Sr element, is 0.2 wt%.

[0204] Comparative Example 1

[0205] (1) Ni 0.8 Co 0.1 Mn 0.1 The (OH)2 precursor, lithium hydroxide, and nano-alumina were mixed uniformly without adding any Sr-containing substances to obtain a mixture, in which n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04, and the Al content was 5000ppm based on the total weight of the multi-element cathode material. The mixture was then subjected to a first sintering in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere was 97vol%. The mixture was then naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0206] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 1g / mL, the washing time is 10min, and the washing temperature is 15℃. Then the slurry is filtered, and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0207] (3) The dried material and Al2O3 were mixed evenly to obtain a mixture. The amount of Al2O3 was such that, based on the total weight of the cathode material, the Al content was 1000 ppm. The mixture was then sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 25℃ to 600℃ at a rate of 3℃ / min, sintering at 600℃ for 8 hours, and then cooling with the furnace. The second sintered material was then sieved to obtain the multi-element cathode material D1. XRD tests were performed on the cathode material D1, and the results are as follows. Figure 1 As shown, by Figure 1 It can be seen that the characteristic peaks of Sr and Ni oxides forming a metal solid solution are absent in the cathode material D1, indicating that no metal oxide solid solution has formed in cathode material D1. Specifically, the composition of cathode material D1 is: Li 1.04 Ni 0.783 Co 0.098 Mn 0.098 Al 0.021 O2.

[0208] Comparative Example 2

[0209] (1) Ni 0.90 Co 0.05 Mn 0.05The precursor (OH)2, lithium hydroxide, nano-zirconia, nano-yttrium oxide, nano-alumina and other dopants are mixed evenly without adding any Sr-containing substances to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.03. Based on the total weight of the multi-element cathode material, the content of Zr is 2500ppm, the content of Y is 1500ppm and the content of Al is 1000ppm. The mixture is sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering are: heating from room temperature to 745℃ at a rate of 2℃ / min, sintering at 745℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere is 93vol%. Then, it is naturally cooled to 80℃ in the furnace, crushed and passed through a 300-mesh sieve to obtain the first sintered material.

[0210] (2) The first sintering material is mixed with water and washed. The solid-liquid ratio is 2g / mL, the washing time is 3min, and the washing temperature is 25℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0211] (3) The dried material and H3BO3 were mixed evenly to obtain a mixture. The amount of H3BO3 was such that, based on the total weight of the cathode material, the content of element B was 1000 ppm. The mixture was sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 25℃ to 400℃ at a rate of 3℃ / min, sintering at 400℃ for 8 hours, and then cooling with the furnace. The second sintered material was then sieved to obtain the multi-element cathode material D2. XRD tests were performed on the cathode material D2. No characteristic peaks of metal oxide solid solutions were observed in the XRD, indicating that no metal oxide solid solutions were formed in the cathode material D2. Specifically, the composition of the cathode material D2 is: Li 1.04 Ni 0.885 Co 0.049 Mn 0.049 Zr 0.003 Y 0.002 Al 0.004 B 0.009 O2.

[0212] Comparative Example 3

[0213] (1) Ni 0.16 Co 0.16 Mn 0.68The (OH)2 precursor and lithium carbonate were mixed uniformly, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.50; the mixture was sintered for the first time in an oxygen-containing atmosphere. The conditions for the first sintering were: heating from room temperature to 850℃ at a rate of 1℃ / min, sintering at 850℃ for 10h, and the oxygen content in the oxygen-containing atmosphere was 21 vol%. Then, the mixture was naturally cooled to 80℃ in the furnace, crushed, and passed through a 300-mesh sieve to obtain the first sintered material.

[0214] Step (2) is the same as in Example 4;

[0215] (3) The dried material was mixed evenly with WO3 to obtain a mixture. The amount of WO3 was such that, based on the total weight of the cathode material, the content of W element was 2000 ppm. The mixture was then sintered a second time in an air atmosphere. The conditions for the second sintering were: heating from 25℃ to 500℃ at a rate of 3℃ / min, sintering at 500℃ for 8 hours, and then cooling with the furnace. The second sintered material was then sieved to obtain the multi-element cathode material D3. XRD tests were performed on the cathode material D3. No characteristic peaks of metal oxide solid solutions were observed in the XRD, indicating that no metal oxide solid solutions were formed in the cathode material D3. The composition of the cathode material D3 was: Li 1.20 Ni 0.129 Co 0.129 Mn 0.542 W 0.001 O2.

[0216] Comparative Example 4

[0217] (1) Ni 0.8 Co 0.1 Mn 0.1 (OH)2 precursor, lithium hydroxide, and nano-alumina are mixed uniformly without adding any Sr-containing substances to obtain a mixture, wherein n(Li) / [n(Ni)+n(Co)+n(Mn)]=1.04, and the Al content is 5000ppm based on the total weight of the precursor. The mixture is then subjected to a first sintering in an oxygen-containing atmosphere. The conditions for the first sintering are: heating from room temperature to 760℃ at a rate of 2℃ / min, sintering at 760℃ for 8 hours, and the oxygen content in the oxygen-containing atmosphere is 97vol%. The mixture is then naturally cooled to 80℃ in the furnace, crushed, and sieved through a 300-mesh sieve to obtain the first sintered material.

[0218] (2) The first sintering material is mixed with lithium carbonate aqueous solution and washed. The solid-liquid ratio is 1g / mL, the washing time is 10min, and the washing temperature is 20℃. Then the slurry is filtered and the obtained solid phase is vacuum dried at 150℃ to obtain the dried material.

[0219] Step (3) is the same as in Example 1; a multi-element cathode material D4 is obtained. XRD analysis of cathode material D4 showed no characteristic peaks of metal oxide solid solutions, indicating that no metal oxide solid solution was formed in cathode material D4. The composition of cathode material D4 is: Li 1.04 Ni 0.783 Co 0.098 Mn 0.098 Al 0.021 O2.

[0220] Table 1

[0221]

[0222]

[0223] As can be seen from the results in Table 1, Examples 1-16, which use Sr element in the preparation of multi-component materials according to the present invention, have lower lithium carbonate content, higher particle strength, and smaller specific surface area (SSA).

[0224] Test case

[0225] The positive electrode materials prepared in the examples and comparative examples were used to prepare pouch cells with conductive carbon black (SP) and polyvinylidene fluoride (PVDF) at a mass ratio of 95.0:2.5:2.5, and graphite was used as the negative electrode. The performance of the prepared pouch cells was tested, and the results are shown in Table 2.

[0226] Table 2

[0227]

[0228] As can be seen from Table 2, after the materials prepared by the method of the present invention are assembled into batteries, the battery volume expansion rate after 30 days of storage at a high temperature of 70°C is significantly lower than that of the comparative example, indicating that the amount of gas generated by the battery during high-temperature storage is reduced. At the same time, the battery's cycle retention rate under the conditions of 45°C and 500 cycles at 1C / 1C is higher than that of the comparative example, indicating that the battery's cycle performance under high-temperature conditions is significantly better than that of the comparative example.

[0229] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A multi-element cathode material, characterized in that, The primary particles of the multi-element cathode material are filled with a metal oxide solid solution as shown in Formula I. SrMe ε O δ Equation I; Where Me is selected from at least one element of Ni and Co; 0 < ε ≤ 4, 0 < δ ≤ 8; The multi-element cathode material has the composition shown in general formula II: Li 1+α Ni x Co y Mn z G' g G'' k O2@ βSrMe ε O δ Formula II In Equation II, 0 ≤ α ≤ 0.2, 0.10 ≤ x ≤ 1, 0 < y ≤ 1, 0 < z ≤ 1, 0 ≤ g ≤ 0.05, 0 ≤ k ≤ 0.05, x + y + z + g + k ≤ 1, 0 < β ≤ 0.010; G' and G'' are each independently selected from at least one element from Mo, Ca, Mg, Fe, Zr, Ti, Zn, Y, W, V, Nb, La, Al, Cr, F and B; The residual Li₂CO₃ content on the surface of the multi-element cathode material is ≤0.15wt%; Based on the total weight of the aforementioned multi-element cathode material, the content of the metal oxide solid solution, calculated using Sr element, is 0.01-0.6 wt%. The specific surface area (SSA) of the multi-element cathode material is 0.2-0.7 m². 2 / g.

2. The multi-element cathode material according to claim 1, wherein, In Equation II, 0 < α ≤ 0.2, 0.30 ≤ x ≤ 1, 0 < y ≤ 0.30, 0 < z ≤ 0.80, 0.005 ≤ g ≤ 0.03, and 0.005 ≤ k ≤ 0.03; And / or, the maximum crushing pressure of the multi-element cathode material is 100-200 MPa.

3. A method for preparing the multi-element cathode material according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) Mix the precursor, lithium source, and Sr-doped compound, or mix the precursor, lithium source, Sr-doped compound and G'-doped compound to obtain a mixture; sinter the mixture in an oxygen-containing atmosphere, crush it, and sieve it to obtain a first sintered material. (2) After mixing and washing the first sintering material with water, solid-liquid separation is performed to obtain a solid phase, and the solid phase is dried to obtain a dried material; (3) The dried material, or the dried material mixed with a coating agent containing G'' element, is sintered a second time to obtain a secondary sintered material; the secondary sintered material is sieved and iron is removed to obtain the multi-element cathode material; The precursor has the composition shown in Formula III: Ni a Co b Mn c (OH)2 of formula III Where 0.10≤a≤1, 0<b≤1, 0<c≤1.

4. The preparation method according to claim 3, wherein, The lithium source is selected from lithium hydroxide and / or lithium carbonate; And / or, the Sr-doped compound is selected from at least one of Sr oxides, Sr hydroxides, Sr salts, and Sr organic compounds; And / or, the compound containing the dopant element G' is selected from compounds that provide at least one element selected from Mo, Ca, Mg, Fe, Zr, Ti, Zn, Y, W, V, Nb, La, Al, Cr, F and B; And / or, the amounts of the precursor and the lithium source are such that 1≤n(Li) / [n(Ni)+n(Co)+n(Mn)]≤1.60; And / or, the amount of the compound containing the doped element Sr is such that, based on the content of the multi-element cathode material, the content of the Sr element is 100-10000 ppm; And / or, the amount of the compound containing doped element G' is such that, based on the content of the multi-element cathode material, the content of element G' is 0-10000 ppm.

5. The preparation method according to claim 4, wherein, The amount of the compound containing the doped element Sr is such that, based on the content of the multi-element cathode material, the content of the Sr element is 100-5000 ppm. And / or, the amount of the compound containing the doped element G' is such that, based on the content of the multi-element cathode material, the content of the G' element is 100-6000 ppm.

6. The preparation method according to any one of claims 3-5, wherein, The oxygen-containing atmosphere is selected from oxygen and / or air; And / or, in Formula III, when a ≥ 0.60, the oxygen concentration in the oxygen-containing atmosphere is ≥ 90 vol% And / or, the conditions for the first sintering include: heating from 20-30°C to 650-1000°C at a heating rate of 0.5-5°C / min, and holding at that temperature for 5-25 hours.

7. The preparation method according to any one of claims 3-5, wherein, In step (2), the solid-liquid ratio of the first sintering material to the water is 0.5-4 g / mL; And / or, the washing conditions include: a washing temperature of 5-30°C and a washing time of 0.5-30 min; And / or, the drying is vacuum drying.

8. The preparation method according to claim 7, wherein, The washing conditions include: a washing temperature of 5-30℃ and a washing time of 1-10 minutes.

9. The preparation method according to any one of claims 3-5, wherein, In step (3), the amount of the coating agent containing G'' element is such that, based on the total weight of the multi-element cathode material, the content of G'' element is 0-10000ppm; And / or, the conditions for the second sintering include: heating from 20-30°C to 200-800°C at a heating rate of 1-10°C / min, and holding at that temperature for 4-20 hours.

10. The preparation method according to claim 9, wherein, In step (3), the amount of the coating agent containing G'' element is such that, based on the total weight of the multi-element cathode material, the content of G'' element is 100-5000 ppm.

11. The application of the multi-element cathode material according to claim 1 or 2 in lithium-ion batteries.

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