Lithium nickel cobalt manganese oxide composite cathode material, preparation method thereof and lithium ion battery

Abstract

The application provides a lithium nickel cobalt manganese oxide composite positive electrode material, a preparation method thereof and a lithium ion battery. The lithium nickel cobalt manganese oxide composite positive electrode material is a lithium transition metal oxide containing tungsten elements and doping elements, wherein the doping elements include one or more of strontium elements, zirconium elements and boron elements, the weight ratio of the tungsten elements to the doping elements is 1:0.1-1:13, and the lithium nickel cobalt manganese oxide composite positive electrode material is a single crystal particle or a single crystal particle agglomerate. Compared with existing ternary positive electrode materials, the high-nickel ternary single crystal positive electrode material with the above composition has more excellent cycle performance, rate performance and specific capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium ion battery manufacturing, in particular to a lithium nickel cobalt manganese oxide composite cathode material, a preparation method thereof and a lithium ion battery. BACKGROUND

[0002] In recent years, batteries as important energy storage devices have also developed rapidly, among which lithium ion batteries have become the new darling of the energy storage field due to their high energy density, suitable working voltage and good cycle performance. However, lithium batteries also have their inherent shortcomings, and the focus of research in this field is mainly concentrated in improving their cycle life, charging rate and safety performance and the like. In the field of lithium ion battery cathode materials, compared with traditional LiCoO2, LiNiO2 and LiMnO2 cathode materials, the capacity of layered high-nickel ternary cathode material is higher, the cycle performance is better, the safety is also good, and the price is low, which makes it become a cathode material with extremely promising development prospects.

[0003] The high capacity of high-nickel ternary cathode material also brings many problems, for example, the shrinkage and expansion of the lattice during the charging and discharging process of the battery causes a large number of microcracks in the material. The continuous expansion of such microcracks eventually leads to the fragmentation of the material structure. At the same time, this also exacerbates the reaction between the electrolyte and the cathode material, leading to irreversible loss of battery capacity and occurrence of more side reactions. As the battery discharges, Li and Ni ions in the cathode material are mixed, leading to a series of problems such as irreversible phase change.

[0004] At present, the structure and cycle stability of high-nickel NCM single crystal cathode material are mainly improved by doping or coating. Common doping elements include Na, Mg, Al, Zr, Cr and Mo, etc. The modification principles mainly include: 1) replacing high-activity elements such as Li and Ni with electrochemically inert and structurally stable elements; 2) preventing cation mixing by increasing the energy barrier of migration; 3) reducing oxygen release during electrochemical cycling by enhancing oxygen-metal bonds. 2+

[0005] Although the cycle stability and other electrochemical properties of the cathode material can be improved by common dopants, there is still a large gap between the actual specific capacity and the first discharge efficiency and the theoretical value. Taking high-nickel NCM811 (molar ratio of Ni, Co and Mn is 8:1:1) as an example, its theoretical discharge specific capacity is about 280 mAh / g, and after treatment with common doping elements, its actual 0.1C discharge specific capacity is mostly only about 200 mAh / g. When W doping is applied to high-nickel single crystal material, it often causes the "refining" of primary particles, resulting in too small primary particle size or even presenting a secondary spherical particle morphology, thereby causing a decrease in the tap density of the single crystal material and an increase in side reactions and a series of other problems. ​

[0006] In view of the above problems, it is necessary to provide a positive electrode material capable of simultaneously satisfying high specific capacity, good cycle performance and high tap density of single crystal material. SUMMARY

[0007] The main purpose of the present application is to provide a nickel cobalt lithium manganate composite positive electrode material, a preparation method thereof and a lithium ion battery, so as to solve the problem that the existing lithium ion battery doped with tungsten element cannot simultaneously satisfy high specific capacity, good cycle performance and high tap density.

[0008] In order to achieve the above-mentioned purpose, the present application provides a nickel cobalt lithium manganate composite positive electrode material, which is a lithium transition metal oxide containing tungsten element and doping element, wherein the doping element includes one or more of strontium element, zirconium element and boron element, the weight ratio of tungsten element to doping element is 1:0.1-1:13, and the nickel cobalt lithium manganate composite positive electrode material is a single crystal particle and / or a single crystal particle agglomerate, preferably, the weight ratio of tungsten element to doping element is 1:0.5-1:8.

[0009] Further, the content of tungsten element is 0.03-0.5wt% and the content of doping element is 0.03-0.6wt% based on the weight percentage content of lithium transition metal oxide in the nickel cobalt lithium manganate composite positive electrode material excluding tungsten element and doping element.

[0010] Further, when the doping element is zirconium element, the content of zirconium element is 0.15-0.6wt% based on the weight percentage content of lithium transition metal oxide in the nickel cobalt lithium manganate composite positive electrode material excluding tungsten element and doping element; and / or when the doping element is boron element, the content of boron element is 0.08-0.5wt% based on the weight percentage content of lithium transition metal oxide in the nickel cobalt lithium manganate composite positive electrode material excluding tungsten element and doping element; and / or when the doping element is strontium element, the content of strontium element is 0.08-0.5wt% based on the weight percentage content of lithium transition metal oxide in the nickel cobalt lithium manganate composite positive electrode material excluding tungsten element and doping element; and / or when the doping element is at least two of strontium element, zirconium element and boron element, the total content of doping element is 0.2-0.5wt%, preferably 0.25-0.4wt%, based on the weight percentage content of lithium transition metal oxide in the nickel cobalt lithium manganate composite positive electrode material excluding tungsten element and doping element.

[0011] Further, when the doping element is strontium element, the weight ratio of tungsten element to strontium element is 1:0.2-1:4, preferably 1:0.5-1:2; and / or when the doping element is zirconium element, the weight ratio of tungsten element to zirconium element is 1:(1-12), preferably 1:(4-7); and / or when the doping element is boron element, the weight ratio of tungsten element to boron element is 1:(1-5); and / or when the doping element is at least two of strontium element, boron element and zirconium element, the weight ratio of tungsten element to each doping element is 1:(1-4); and / or when the doping element is at least two of strontium element, boron element and zirconium element, the weight ratio of tungsten element to the total weight of the doping elements is 1:(4-8), preferably 1:(5.5-8).

[0012] Further, the doping element further comprises one or more of the group consisting of Ba, Zn, Sr, Nb, Cr, Sn, Mg, Y and Al.

[0013] Further, the nickel cobalt lithium manganate composite positive electrode material adopts the following general formula: Li[(Ni x Co y Mn z ) 1-a-b- c L a M b W c ]O2, wherein 0.6≤x<1, 0<y<1, 0<z<1, x+y+z=1, L, M are independently selected from the doping element, the values of a, b are 0-0.05, and a and b are not 0 at the same time, the value of c is 2×10 -4 -0.002.

[0014] Further, the average particle size of the nickel cobalt lithium manganate composite positive electrode material is 2-5 μm.

[0015] Another aspect of the present application also provides a preparation method of the nickel cobalt lithium manganate composite positive electrode material provided by the present application, the preparation method of the nickel cobalt lithium manganate composite positive electrode material comprises: dosing a nickel cobalt manganate precursor, a doping raw material, a tungsten source and a lithium source according to a predetermined ratio, and performing heat preservation calcination to obtain the nickel cobalt lithium manganate composite positive electrode material, the doping raw material is used to provide one or more of the group consisting of strontium element, zirconium element and boron element.

[0016] Further, the nickel cobalt manganate precursor is Ni 0.83 Co 0.12 Mn 0.05(OH)2 represents, the molar ratio of the nickel cobalt manganese hydroxide precursor and the lithium source is 1:(1-1.05), and / or in the compounding process, when the doping element is strontium element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element, the addition amount of the tungsten element, and the addition amount of the strontium element in the nickel cobalt lithium manganate composite positive electrode material is 100:(0.05-0.4):(0.1-0.5), and / or in the compounding process, when the doping element is zirconium element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element, the addition amount of the tungsten element, and the addition amount of the zirconium element in the nickel cobalt lithium manganate composite positive electrode material is 100:(0.05-0.1):(0.1-0.6), and / or in the compounding process, when the doping element is boron element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element, the addition amount of the tungsten element, and the addition amount of the boron element in the nickel cobalt lithium manganate composite positive electrode material is 100:(0.05-0.1):(0.1-0.5), and / or in the compounding process, when the doping element is strontium element and boron element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element, the addition amount of the tungsten element, the addition amount of the strontium element, and the addition amount of the boron element in the nickel cobalt lithium manganate composite positive electrode material is 100:(0.05-0.4):(0.1-0.4):(0.1-0.4), and / or in the compounding process, when the doping element is strontium element and zirconium element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element, the addition amount of the tungsten element, the addition amount of the strontium element, and the addition amount of the zirconium element in the nickel cobalt lithium manganate composite positive electrode material is 100:(0.05-0.4):(0.1-0.4):(0.1-0.4), and / or in the compounding process, when the doping element is zirconium element and boron element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element, the addition amount of the tungsten element, the addition amount of the zirconium element, and the addition amount of the boron element in the nickel cobalt lithium manganate composite positive electrode material is 100:(0.05-0.4):(0.1-0.4):(0.1-0.4).

[0017] Further, the tungsten source is selected from one or more of the group consisting of tungsten trioxide, phosphotungstic acid, and ammonium metatungstate; and / or the strontium source is one or more of the group consisting of strontium oxide, strontium carbonate; and / or the zirconium source is selected from one or more of the group consisting of zirconium phosphate, zirconium oxide; and / or the boron source is selected from one or more of the group consisting of boric acid, boron oxide, and sodium tetraborate.

[0018] Further, the temperature of the heat preservation calcination is 750-950℃, and the heat preservation time is 12-18h; preferably, the temperature of the heat preservation calcination is 800-900℃; the heating rate of the heat preservation calcination process is 0.8-3℃ / min, preferably 1-2.5℃ / min.

[0019] The lithium ion battery further comprises the positive electrode material, and the positive electrode material comprises the lithium nickel cobalt manganese oxide composite positive electrode material provided by the application or is prepared by using the preparation method of the lithium nickel cobalt manganese oxide composite positive electrode material provided by the application.

[0020] By limiting the ratio of tungsten elements and doping elements in the range, the synergistic effect of the two elements is fully played, on the one hand, the growth of the positive electrode material crystal grains is inhibited, and single crystal particles and / or single crystal particle agglomerates are obtained; this is beneficial to improve the compaction density of the positive electrode material and reduce the probability of occurrence of side reactions; on the other hand, the doping of tungsten elements and the above-mentioned doping elements in the surface layer and the interior of the high-nickel ternary single crystal positive electrode material can also greatly improve the energy density, cycle performance and specific capacity and other performances of the positive electrode material. On this basis, compared with the existing ternary positive electrode material, the high-nickel ternary single crystal positive electrode material with the above composition has the advantages of high compaction density, more excellent cycle performance, rate performance and specific capacity. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application is not limited by the accompanying drawings.

[0022] Figure 1 The scanning electron microscope (SEM) images of the final products of W-0.05 / Sr-0.1 prepared in Example 1 and W-0.4 / Sr-0.4 prepared in Example 2.

[0023] Figure 2 The scanning electron microscope (SEM) images of the final products of Mg-0.1 prepared in Example 1 and Al-0.1 prepared in Example 2.

[0024] Figure 3 The scanning electron microscope (SEM) images of the final products of W-0.05 prepared in Example 1 and W-0.1 / Sr-0.05 prepared in Example 2.

[0025] Figure 4 The 1C cycle performance diagram of the CR2025 button cell assembled by using the positive electrode material in Example 1 at 25 DEG C in the voltage interval of 2.75-4.35V.

[0026] Figure 5 The 1C cycle performance diagram of the CR2025 button cell assembled by using the positive electrode material in Example 2 at 25 DEG C in the voltage interval of 2.75-4.35V. DETAILED DESCRIPTION

[0027] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. The present application will be described in detail below in combination with the embodiments.

[0028] In this article, the term "one or more" refers to one, two, three, four, five, six, seven or more.

[0029] As described in the background, the existing tungsten-doped lithium-ion battery cannot simultaneously meet the performance requirements of high specific capacity, good cycle performance and high compaction density. In order to solve the above technical problems, the present application provides a nickel-cobalt-lithium manganate composite positive electrode material, which is a lithium transition metal oxide containing tungsten elements and doping elements, wherein the doping elements include one or more of strontium elements, zirconium elements and boron elements. The weight ratio of tungsten elements to doping elements is 1:0.1 to 1:13. And the nickel-cobalt-lithium manganate composite positive electrode material is a single crystal particle and / or a single crystal particle agglomerate.

[0030] The above-mentioned nickel-cobalt-lithium manganate composite positive electrode material contains tungsten elements and doping elements (one or more of the group consisting of strontium elements, zirconium elements and boron elements) at the same time. In an embodiment, both tungsten elements and doping elements exist in the positive electrode material by doping. The doping of tungsten elements can inhibit the H2→H3 phase transition and lattice distortion during the charging and discharging process of the battery, thereby reducing the shrinkage and expansion of the positive electrode material lattice and improving the cycle stability of the battery. The addition of specific doping elements not only increases the primary particle size of the nickel-cobalt-lithium manganate composite positive electrode material and inhibits the formation of spherical secondary particles, but also realizes the compromise of discharge specific capacity, cycle stability and primary particle size, which is also beneficial to reduce the melting point and energy consumption of high-temperature solid-phase reaction, reduce Li-Ni mixing, and further improve the energy density and structural stability of the positive electrode material. By limiting the ratio of tungsten elements and doping elements within the above range, the synergistic effect of the two can be fully utilized, on the one hand, the grain growth of the positive electrode material can be inhibited to obtain single crystal particles and / or single crystal particle agglomerates; this is beneficial to improve the compaction density of the positive electrode material and reduce the probability of side reactions; on the other hand, the doping of tungsten elements and the above-mentioned doping elements in the surface layer and the interior of the high-nickel ternary single crystal positive electrode material can also greatly improve the energy density, cycle performance and specific capacity of the positive electrode material. On this basis, compared with the existing ternary positive electrode material, the high-nickel ternary single crystal positive electrode material with the above composition has the advantages of high compaction density, excellent cycle performance, rate performance and specific capacity.

[0031] It should be noted that the single crystal particle refers to the particles inside the crystal body arranged regularly and periodically in three-dimensional space, or the whole crystal body is composed of the same space lattice in three-dimensional direction, and the arrangement of the whole crystal body in space is long-range ordered.

[0032] The single crystal particle agglomerate is an agglomerate formed by single crystal particles, and does not belong to the category of polycrystal particles, and the morphology is not spherical or spheroidal.

[0033] The weight ratio of the tungsten element to the doping element can be 1:0.1, 1:0.2, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, or 1:13. To further improve the synergistic effect between the tungsten element and the doping element, preferably, the weight ratio of the tungsten element to the doping element is 1:0.5 to 1:8.

[0034] To further improve the electrical performance of the nickel-cobalt-lithium-manganese composite positive electrode material, preferably, the content of the tungsten element is 0.03 to 0.5 wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium-manganese composite positive electrode material excluding the tungsten element and the doping element. For example, the content of the tungsten element is 0.0300 wt%, 0.0400 wt%, 0.0450 wt%, 0.0475 wt%, 0.0500 wt%, 0.0600 wt%, 0.0800 wt%, 0.0900 wt%, 0.0947 wt%, 0.0951 wt%, 0.0963 wt%, 0.0967 wt%, 0.1000 wt%, 0.2000 wt%, 0.3746 wt%, 0.4000 wt%, or 0.5000 wt%. The content of the doping element is 0.05 to 0.6 wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium-manganese composite positive electrode material excluding the tungsten element and the doping element. For example, the content of the doping element is 0.0500 wt%, 0.0800 wt%, 0.0949 wt%, 0.0951 wt%, 0.0955 wt%, 0.100 wt%, 0.1901 wt%, 0.200 wt%, 0.2842 wt%, 0.2863 wt%, 0.300 wt%, 0.3326 wt%, 0.350 wt%, 0.4000 wt%, 0.4500 wt%, 0.5000 wt%, 0.5500 wt%, or 0.6000 wt%. More preferably, the content of the tungsten element is 0.05 to 0.1 wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium-manganese composite positive electrode material excluding the tungsten element and the doping element. The content of the doping element is 0.1 to 0.4 wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium-manganese composite positive electrode material excluding the tungsten element and the doping element.

[0035] The addition of the doping element not only increases the primary particle size of the nickel-cobalt-lithium manganate composite cathode material and inhibits the formation of spherical secondary particles, but also realizes the consideration of the discharge specific capacity, cycle stability and primary particle size, is conducive to reducing the melting point and energy consumption of the high-temperature solid-phase reaction, reducing Li-Ni mixing, and further improving the energy density and structural stability of the cathode material. By limiting the amount of the doping element, the comprehensive performance of the nickel-cobalt-lithium manganate composite cathode material can be further improved.

[0036] In a preferred embodiment, when the doping element is zirconium, the content of zirconium is 0.15-0.6wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium manganate composite cathode material excluding the tungsten element and the doping element. For example, the content of zirconium can be 0.15wt%, 0.18wt%, 0.2wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.5wt%, or 0.6wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium manganate composite cathode material excluding the tungsten element and the doping element.

[0037] In a preferred embodiment, when the doping element is boron, the content of boron is 0.08-0.5wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium manganate composite cathode material excluding the tungsten element and the doping element. For example, the content of boron can be 0.09wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, or 0.5wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium manganate composite cathode material excluding the tungsten element and the doping element.

[0038] In a preferred embodiment, when the doping element is strontium, the content of strontium is 0.08-0.5wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium manganate composite cathode material excluding the tungsten element and the doping element. For example, the content of strontium can be 0.09wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, or 0.5wt% based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium manganate composite cathode material excluding the tungsten element and the doping element.

[0039] In a preferred embodiment, when the doping element is at least two of strontium, zirconium and boron, the total content of the doping element is 0.2-0.5wt%, preferably 0.25-0.4wt%, based on the weight percentage content of the lithium transition metal oxide in the nickel-cobalt-lithium manganate composite cathode material excluding the tungsten element and the doping element.

[0040] When the doping elements are strontium and boron, the content of boron may be, for example, 0.1 wt%, 0.18 wt%, 0.2 wt%, 0.3 wt%, based on the weight percentage of lithium transition metal oxide in the nickel-cobalt-lithium manganate composite positive electrode material excluding the tungsten element and the doping elements. The content of strontium may be, for example, 0.08 wt%, 0.1 wt%, 0.2 wt%. The total content of the doping elements may be, for example, 0.2 wt%, 0.28%, 0.3 wt%, 0.4 wt%, 0.5 wt%.

[0041] When the doping elements are zirconium and boron, the content of boron may be, for example, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, and the content of zirconium may be, for example, 0.1 wt%, 0.18 wt%, 0.2 wt%, based on the weight percentage of lithium transition metal oxide in the nickel-cobalt-lithium manganate composite positive electrode material excluding the tungsten element and the doping elements. The total content of the doping elements may be, for example, 0.2 wt%, 0.28%, 0.3 wt%, 0.4 wt%, 0.5 wt%.

[0042] When the doping elements are strontium and zirconium, the content of strontium may be, for example, 0.1 wt%, 0.18 wt%, 0.2 wt%, and the content of zirconium may be, for example, 0.1 wt%, 0.18 wt%, 0.2 wt%, 0.3 wt%, based on the weight percentage of lithium transition metal oxide in the nickel-cobalt-lithium manganate composite positive electrode material excluding the tungsten element and the doping elements. The content of the doping elements may be, for example, 0.2 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.5 wt%.

[0043] Due to slight differences in performance between different doping elements, in order to further improve the synergistic effect of a specific doping element and tungsten and further improve the comprehensive performance of the nickel-cobalt-lithium manganate composite positive electrode material, the ratio of the doping element to tungsten needs to be further limited according to the type of the doping element.

[0044] In a preferred embodiment, when the doping element is strontium, the weight ratio of tungsten to strontium is 1:0.2-1:4. For example, when the doping element is strontium, the weight ratio of tungsten to strontium may be 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:1, 1:2, 1:3, 1:4. More preferably, when the doping element is strontium, the weight ratio of tungsten to the doping element is 1:0.5-1:2.

[0045] In a preferred embodiment, when the doping element is zirconium element, the weight ratio of tungsten element to zirconium element is 1:(1-12), such as when the doping element is zirconium element, the weight ratio of tungsten element to zirconium element is 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, preferably 1:(4-7); and / or when the doping element is boron element, the weight ratio of tungsten element to boron element is 1:(1-5), such as when the doping element is boron element, the weight ratio of tungsten element to boron element is 1:1, 1:2, 1:3, 1:4, 1:5; and / or

[0046] When the doping element is at least two of strontium element, boron element and zirconium element, the weight ratio of tungsten element to each doping element is 1:(1-4), such as 1:1, 1:2, 1:3, 1:4;

[0047] When the doping element is at least two of strontium element, zirconium element and boron element, the ratio of the weight of tungsten element to the total weight of the doping elements is 1:(4-8). Such as 1:4, 1:5, 1:5.8, 1:6, 1:7, 1:8, preferably 1:(5.5-8).

[0048] In order to further improve the comprehensive performance of the lithium nickel manganese composite positive electrode material, preferably, the above-mentioned doping element can also include other kinds of doping elements, such as one or more of the group consisting of Ba, Zn, Sr, Nb, Cr, Sn, Mg, Y and Al.

[0049] In a preferred embodiment, the above-mentioned lithium nickel cobalt manganese composite positive electrode material is represented by the following general formula: Li[(Ni x Co y Mn z ) 1-a-b-c L a M b W c ]O2, wherein 0.6≤x<1, 0<y<1, 0<z<1, x+y+z=1, L, M are independently selected from the above-mentioned doping elements, the values of a, b are 0-0.05, and a and b are not 0 at the same time, the value of c is 2x10 -4~0.002. In the above formula, on the basis of satisfying x+y+z=1, x can be, for example, 0.6, 0.7, 0.8, 0.83, 0.9, y can be, for example, 0.1, 0.12, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, z can be, for example, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, a and b can be the same or different, and can be, for example, 0, 0.00053, 0.00102, 0.00106, 0.00204, 0.00210, 0.00300, 0.00423, 0.00612, 0.00860, 0.01000, 0.02000, 0.03000, 0.03440, 0.00357, 0.04000, 0.04300, 0.05000; c can be, for example, 0.000200, 0.000252, 0.000254, 0.000400, 0.000504, 0.000600, 0.000800, 0.001000, 0.001200, 0.001400, 0.001600, 0.001800, 0.002000.

[0050] To further improve the comprehensive performance of the lithium-nickel-manganese composite positive electrode material, in a preferred embodiment, the content of the tungsten element can be, for example, 0.0473wt%, 0.0474wt%, 0.0475wt%, 0.0477wt%, 0.0947wt%, 0.0951wt%, 0.0963wt%, 0.0967wt%, 0.3746wt%, based on the weight percentage content of the lithium transition metal oxide removing the tungsten element and the doping element in the lithium nickel cobalt manganese composite positive electrode material.

[0051] In a preferred embodiment, the total content of the doping element can be, for example, 0.0475wt%, 0.0949wt%, 0.0951wt%, 0.0954wt%, 0.0955wt%, 0.1901wt%, 0.2842wt%, 0.2863wt%, 0.3326wt%, 0.3777wt%, 0.3779wt%, 0.3866wt%, 0.4854wt%, 0.5697wt%, based on the weight percentage content of the lithium transition metal oxide removing the tungsten element and the doping element in the lithium nickel cobalt manganese composite positive electrode material.

[0052] In a preferred embodiment, the content of strontium element may be, for example, 0.0475 wt%, 0.0949 wt%, 0.1879 wt%, 0.1888 wt%, 0.3777 wt%, in terms of the weight percentage of lithium transition metal oxide in the lithium nickel cobalt manganese composite positive electrode material from which the tungsten element and the doping element are removed.

[0053] In a preferred embodiment, the content of zirconium element may be, for example, 0.0951 wt%, 0.1900 wt%, 0.1901 wt%, 0.1909 wt%, 0.3326 wt%, 0.5697 wt%, in terms of the weight percentage of lithium transition metal oxide in the lithium nickel cobalt manganese composite positive electrode material from which the tungsten element and the doping element are removed.

[0054] In a preferred embodiment, the content of boron element may be, for example, 0.0954 wt%, 0.0955 wt%, 0.3866 wt%, 0.4854 wt%, in terms of the weight percentage of lithium transition metal oxide in the lithium nickel cobalt manganese composite positive electrode material from which the tungsten element and the doping element are removed.

[0055] By limiting the weight ratio of lithium element, cobalt element, nickel element, manganese element, tungsten element and doping element in the lithium nickel cobalt manganese composite positive electrode material within the above range, on the one hand, it is beneficial to further improve the structural stability and energy density of the lithium nickel cobalt manganese composite positive electrode material, and on the other hand, it is also beneficial to further improve its cycle performance and specific capacity.

[0056] In order to further improve the compaction density, cycle performance and specific capacity of the positive electrode material, preferably, the average particle size of the lithium nickel cobalt manganese composite positive electrode material is 2-5 μm.

[0057] Another aspect of the present application also provides a preparation method of the lithium nickel cobalt manganese composite positive electrode material provided by the present application. The preparation method of the lithium nickel cobalt manganese composite positive electrode material comprises: proportioning a nickel cobalt manganese oxide precursor, a doping raw material, a tungsten source and a lithium source according to a predetermined ratio, and performing heat preservation calcination to obtain the lithium nickel cobalt manganese composite positive electrode material. The doping raw material is used to provide one or more of the group consisting of the required strontium element, zirconium element and boron element.

[0058] Compared with the existing ternary positive electrode material, the high-nickel ternary single crystal positive electrode material prepared by the above method is a single crystal particle or a single crystal particle agglomerate, which has more excellent cycle performance, rate performance and specific capacity. At the same time, the above preparation method also has the advantages of simple process, industrial production, and can be used for tungsten element and doping element doping on the surface and inside of other ternary positive electrode materials or lithium-rich positive electrode materials, thus having high economic value.

[0059] In a preferred embodiment, the nickel cobalt manganese oxide precursor is Ni0.83 Co 0.12 Mn 0.05 (OH)2 represents, the molar ratio of the nickel cobalt manganese hydroxide precursor to the lithium source is 1:(1-1.05). Ni can improve the specific capacity of the positive electrode material, when the content of the element is high, it is easy to aggravate the mixed arrangement of cations, the addition of Co element can inhibit the mixed arrangement of cations, thereby improving the stability of the positive electrode material, and the addition of Mn element can improve the safety and thermal stability of the positive electrode material, while reducing the cost. Limiting the amount of nickel cobalt manganese hydroxide precursor, lithium source, tungsten element and doping element in the above range is beneficial to improve the proportion of single crystal particles in the prepared lithium nickel cobalt manganese oxide composite positive electrode material, thereby further improving the energy density, cycle performance and structural stability of the positive electrode material. For example, the molar ratio of the nickel cobalt manganese hydroxide precursor to the lithium source is 1:1, 1:1.03, 1:1.05.

[0060] The tungsten source and doping raw materials used in the preparation process of the above-mentioned lithium nickel cobalt manganese oxide composite positive electrode material can be selected from the commonly used types in the art. In a preferred embodiment, the tungsten source includes but is not limited to one or more of the group consisting of tungsten trioxide, phosphotungstic acid and ammonium metatungstate. The doping raw material includes a strontium source, a zirconium source and a boron source, wherein the strontium source includes but is not limited to one or more of the group consisting of strontium oxide, strontium carbonate; and / or, the zirconium source includes but is not limited to one or more of the group consisting of zirconium phosphate, zirconium oxide, and the boron source includes but is not limited to one or more of the group consisting of boric acid, boron oxide and sodium tetraborate.

[0061] Due to the slight difference in performance of each doping element, in order to further improve the comprehensive performance of the lithium nickel cobalt manganese oxide composite positive electrode material, the proportion of each element in the batching process can be further optimized for each doping element. In a preferred embodiment, in the batching process, when the doping element is strontium element, the weight ratio of the addition amount of lithium transition metal oxide excluding tungsten element and doping element, the addition amount of tungsten element and the addition amount of strontium element in the lithium nickel cobalt manganese oxide composite positive electrode material is 100:(0.05-0.4):(0.1-0.5), for example, it can be selected from 100:0.05:0.1, 100:0.05:0.2, 100:0.05:0.3, 100:0.05:0.4, 100:0.1:0.1, 100:0.1:0.2, 100:0.1:0.3, 100:0.1:0.4, 100:0.2:0.1, 100:0.2:0.2, 100:0.2:0.3, 100:0.2:0.4, 100:0.3:0.1, 100:0.3:0.2, 100:0.3:0.3, 100:0.3:0.4, 100:0.4:0.1, 100:0.4:0.2, 100:0.4:0.3, 100:0.4:0.4 or 100:0.4:0.5.

[0062] In the compounding process, when the doping element is zirconium element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element in the nickel-cobalt-lithium manganate composite positive electrode material to the added amount of the tungsten element and the added amount of the zirconium element is 100:(0.05-0.1):(0.1-0.6), which can be selected from 100:0.05:0.1, 100:0.05:0.2, 100:0.05:0.3, 100:0.05:0.4, 100:0.1:0.1, 100:0.1:0.2, 100:0.1:0.3, 100:0.1:0.35, 100:0.1:0.4 or 100:0.1:0.6, for example.

[0063] In the compounding process, when the doping element is boron element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element in the nickel-cobalt-lithium manganate composite positive electrode material to the added amount of the tungsten element and the added amount of the boron element is 100:(0.05-0.1):(0.1-0.5), which can be selected from 100:0.05:0.1, 100:0.05:0.2, 100:0.05:0.3, 100:0.05:0.4, 100:0.1:0.1, 100:0.1:0.2, 100:0.1:0.3, 100:0.1:0.4 or 100:0.1:0.5, for example.

[0064] In the compounding process, when the doping element is strontium element and boron element, the weight ratio of the lithium transition metal oxide removing the tungsten element and the doping element in the nickel-cobalt-lithium manganate composite positive electrode material to the added amount of the tungsten element, the added amount of the strontium element and the added amount of the boron element is 100:(0.05-0.4):(0.1-0.4):(0.1-0.4), which can be selected from 100:0.05:0.1:0.1, 100:0.05:0.1:0.2, 100:0.05:0.1:0.3, 100:0.05:0.2:0.1, 100:0.05:0.2:0.2, 100:0.05:0.2:0.3, 100:0.05:0.2:0.4, 100:0.05:0.3:0.1, 100:0.05:0.4:0.1, for example.

[0065] In the compounding process, when the doping elements are strontium and zirconium, the weight ratio of lithium transition metal oxide removing the tungsten element and the doping elements, the addition amount of the tungsten element, the addition amount of the strontium element and the addition amount of the zirconium element in the nickel-cobalt-lithium manganate composite positive electrode material is 100:(0.05-0.4):(0.1-0.4):(0.1-0.4). For example, it can be selected from 100:0.05:0.1:0.4, 100:0.05:0.1:0.1, 100:0.05:0.2:0.1, 100:0.05:0.2:0.2, 100:0.05:0.3:0.1, 100:0.05:0.4:0.1.

[0066] In the compounding process, when the doping elements are zirconium and boron, the weight ratio of lithium transition metal oxide removing the tungsten element and the doping elements, the addition amount of the tungsten element, the addition amount of the zirconium element and the addition amount of the boron element in the nickel-cobalt-lithium manganate composite positive electrode material is 100:(0.05-0.4):(0.1-0.4):(0.1-0.4). For example, it can be selected from 100:0.05:0.1:0.1, 100:0.05:0.1:0.2, 100:0.05:0.1:0.3, 100:0.05:0.2:0.1, 100:0.05:0.2:0.2, 100:0.05:0.2:0.3, 100:0.05:0.2:0.4, 100:0.05:0.3:0.1, 100:0.05:0.4:0.1.

[0067] In a preferred embodiment, the temperature of the heat preservation calcination is 750-950℃. The heat preservation time is 12-18h. If the heat preservation time is too short, the crystallinity will be reduced and the crystal will have defects; if the heat preservation time is too long, the mixing of Li and Ni will be intensified, the cost will be high and the production capacity will be reduced. Limiting the temperature and the heat preservation time of the heat preservation calcination process in the above range is beneficial to further improve the crystallinity of the nickel-cobalt-lithium manganate composite positive electrode material, make the surface more dense, and thus further improve the energy density, the cycle performance and the structural stability of the nickel-cobalt-lithium manganate composite positive electrode material. For example, the temperature of the heat preservation calcination is 750℃, 800℃, 850℃, 860℃, 900℃, 950℃, and the heat preservation time can be 12h, 13h, 14h, 15h, 16h, 17h, 18h. In order to further improve the crystallinity of the single crystal material, reduce the crystal defects, and further improve the specific capacity and the cycle of the nickel-cobalt-lithium manganate composite positive electrode material, more preferably, the temperature of the heat preservation calcination is 800-900℃.

[0068] If the heating rate is too fast when the target calcination temperature is reached, the waste gas (mainly water vapor) generated during the calcination process cannot be discharged in time, which may lead to an increase in residual alkali in the lithium nickel cobalt manganese oxide composite cathode material, surface damage, increased impedance, and consequently affect its performance. To reduce the likelihood of these defects and further improve the overall performance of the cathode material, preferably, the heating rate during the holding calcination process is 0.8–3 °C / min, such as 1, 1.5 °C / min, 2 °C / min, 2.5 °C / min, or 3 °C / min. More preferably, the heating rate during the holding calcination process is 1–2.5 °C / min.

[0069] Another aspect of this application provides a lithium-ion battery, including a positive electrode material, which includes the lithium nickel cobalt manganese oxide composite positive electrode material provided in this application or is prepared using the method for preparing the lithium nickel cobalt manganese oxide composite positive electrode material provided in this application.

[0070] Since doping tungsten and other doping elements on the surface and inside of high-nickel ternary single-crystal cathode materials can greatly improve the cycle performance, rate performance and specific capacity of lithium nickel cobalt manganese oxide composite cathode materials, lithium-ion batteries containing the above-mentioned lithium nickel cobalt manganese oxide composite cathode materials also have excellent electrical performance.

[0071] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0072] Example 1

[0073] A method for preparing a lithium nickel cobalt manganese oxide composite cathode material includes:

[0074] Nickel cobalt manganese oxide precursor (Ni 0.83 Co 0.12 Mn 0.05 (OH)2), strontium source (strontium carbonate), tungsten source (tungsten trioxide), and LiOH·H2O are added to a high-speed mixer and mixed to obtain a uniformly mixed solid powder. LiOH·H2O and the precursor Ni 0.83 Co 0.12 Mn 0.05 The molar ratio of (OH)₂ is 1.05:1, and the amounts of tungsten and strontium added are respectively LiNi 0.83 Co 0.12 Mn 0.050.05wt%, 0.1wt% of O2 (lithium transition metal oxide with tungsten element and doping element removed). The final product is recorded as W-0.05 / Sr-0.1, with the general formula of Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c Sr a W c ]O2, wherein a = 1.06 x 10 -3 , c = 2.52 x 10 -4 . The SEM image is shown in Figure 1 .

[0075] The above solid powder is calcined at 850°C for 15 hours under an oxygen atmosphere, with a heating rate of 1.5°C / min during the calcination stage. After cooling, a Sr-W double-doped modified high-nickel single-crystal ternary positive electrode material (containing both single-crystal particles and single-crystal agglomerates) is obtained.

[0076] The doping agent strontium carbonate-tungsten trioxide is replaced by magnesium oxide and tungsten trioxide, respectively. The content of magnesium element is 0.1wt% based on the percentage content of lithium transition metal oxide with tungsten element and doping element removed; the content of tungsten element is 0.05wt% based on the percentage content of lithium transition metal oxide with tungsten element and doping element removed. The positive electrode active material is prepared in the same way. The final product is recorded as Mg-0.1 and W-0.05, with the general formula of Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1- a Mg a ]O2 and Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-c W c ]O2, wherein a = 3.83 x 10 -3 , c = 2.52 x 10 -4 .

[0077] The SEM test results of the final product are shown in Figures 1-3 The primary particles of the final product W-0.05 / Sr-0.1 have good dispersity, with a size of about 3 microns; the primary particles of Mg-0.1 also have a size of about 3 microns, with a smooth surface. Due to the "refinement" of W on the primary particles, the primary particles do not grow, with a length of about 1.5 microns and a width of about 0.75 microns, and severe agglomeration.

[0078] The sample was subjected to constant current charge-discharge test at 25℃, 1C rate, 2.75V-4.35V voltage range, and the results are shown in Table 1. Figure 4 As shown in Table 1, the discharge capacity of W-0.05 / Sr-0.1 in the first cycle was 188.8 mAh / g, the discharge capacity after 100 cycles was 156.93 mAh / g, and the capacity retention rate was 83.12%. Under the same test conditions, the discharge capacity of Mg-0.1 in the first cycle was 181.6 mAh / g, the discharge capacity after 100 cycles was 125.70 mAh / g, and the capacity retention rate was only 69.22%. The discharge capacity of W-0.05 in the first cycle was 188.3 mAh / g, the discharge capacity after 100 cycles was 146.40 mAh / g, and the capacity retention rate was 77.75%.

[0079] The rate performance test was carried out at 25℃ in the voltage range of 2.75V-4.35V, and the results are shown in Table 1.

[0080] Table 1

[0081]

[0082] From the above data, compared with W-0.05, the discharge capacity of W-0.05 / Sr-0.1 did not decrease, and the charge-discharge efficiency was higher; but due to the large amount of Sr doping, the rate performance was slightly reduced. Nevertheless, the discharge capacity of W-0.05 / Sr-0.1 was significantly better than Mg-0.1 under the same voltage window and temperature, with a discharge capacity of about 6 mAh / g higher than Mg-0.1.

[0083] Example 2

[0084] The preparation method of the lithium nickel cobalt manganese oxide composite positive electrode material comprises the following steps: mixing a nickel cobalt manganese oxide precursor (Ni 0.83 Co 0.12 Mn 0.05 (OH)2), a strontium source (strontium carbonate), and a tungsten source (tungsten trioxide), and LiOH·H2O into a high-speed mixer to obtain a uniformly mixed solid powder, the molar ratio of LiOH·H2O to the precursor Ni 0.83 Co 0.12 Mn 0.05 (OH)2) is 1.05:1, and the addition amounts of strontium and tungsten are 0.4wt% and 0.4wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide without tungsten and doping elements) respectively, and the final product is recorded as W-0.4 / Sr-0.4, and the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05) 1-a-c Sr a W c ]O2, wherein a = 4.23 x 10 -3 , c = 2.00 x 10 -3 .

[0085] The solid powder is calcined at 860°C for 13 hours under an oxygen atmosphere, with a heating rate of 1.5°C / min, and the final product is a Sr-W double-doped modified high-nickel single-crystal ternary positive electrode material.

[0086] The dopant strontium carbonate-tungsten trioxide is replaced by tungsten trioxide and strontium carbonate and a mixture thereof, and aluminum oxide, and the tungsten element accounts for 0.1wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide without tungsten element and doping element), the strontium element accounts for 0.05wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide without tungsten element and doping element), and the aluminum oxide accounts for 0.1wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide without tungsten element and doping element). In the same way, the positive electrode active material is prepared, and the final product is recorded as W-0.1 / Sr-0.05, Al-0.1, and the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c Sr a W c ]O2, wherein a = 5.30 x 10 -4 , c = 5.04 x 10 -4 , Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a Al a ]O2, wherein a = 3.44 x 10 -3 .

[0087] The SEM test results of the final product are as follows: Figures 1 to 3As shown, the final products are all single crystal particles and agglomerates of single crystal particles, and the primary particles of W-0.4 / Sr-0.4 are well dispersed, with a size of about 3 microns; Al-0.1 has similar primary particle size, but there is slight agglomeration; due to the low ratio of Sr / W doping amount, the primary particles of W-0.1 / Sr-0.05 sample have not grown; although there is no obvious spherical primary particle agglomerate, the agglomeration is serious, and the primary particle size is only about 1.5 x 0.9 microns.

[0088] The samples were subjected to constant current charge and discharge test at 25°C, 1C rate, and 2.75V-4.35V voltage range, and the results are shown in Table 1. Figure 5 As shown, the first cycle discharge specific capacity of W-0.4 / Sr-0.4 is 200.30 mAh / g, the discharge capacity after 100 cycles is 175.20 mAh / g, and the capacity retention rate is 87.47%. Under the same test conditions, the first cycle discharge capacity of Al-0.1 is 174.70 mAh / g, the discharge capacity after 100 cycles is 127.00 mAh / g, and the capacity retention rate is only 72.69%. The first cycle discharge capacity of W-0.1 / Sr-0.05 is 192.80 mAh / g, the discharge capacity after 100 cycles is 151.50 mAh / g, and the capacity retention rate is 78.58%.

[0089] The rate performance test was carried out at 25°C in the voltage range of 2.75V-4.35V, and the results are shown in Table 2.

[0090] Table 2

[0091]

[0092] As shown in Table 2, the first discharge specific capacity, first efficiency and rate performance of W-0.4 / Sr-0.4 are all significantly better than those of W-0.1 / Sr-0.05 sample, and the 1C discharge specific capacity is 25 mAh / g higher than that of Al-0.1 sample. It can be seen that with the increase of W doping amount, the specific capacity of the final product has been significantly increased, and the rate performance is excellent.

[0093] Example 3

[0094] The difference from Example 1 is that the doping element is zirconium element, and in the formed product, the strontium element accounts for 0.4wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (remove tungsten element and doping element lithium transition metal oxide) 0.05wt%, zirconium element accounts for 0.1wt% of LiNi 0.83 Co 0.12 Mn 0.050.1wt% of O2 (lithium transition metal oxide removing tungsten element and doping element), the final product is recorded as W-0.05 / Zr-0.1, the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c Zr a W c ]O2, wherein a = 1.02 x 10 -3 , c = 2.52 x 10 -4 .

[0095] The first cycle discharge capacity is 176.40 mAh / g, the discharge capacity after 100 cycles is 143.94 mAh / g, and the capacity retention rate is 81.60% in the voltage range of 2.75V-4.35V at 25°C and 1C rate.

[0096] Example 4

[0097] The difference from Example 1 is that the doping element is boron element, and in the formed product, the tungsten element accounts for 0.05wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element), the B element accounts for 0.1wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element), the final product is recorded as W-0.05 / B-0.1, the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c B a W c ]O2, wherein a = 8.6 x 10 -3 , c = 2.52 x 10 -4 .

[0098] The first cycle discharge capacity is 173.17 mAh / g, the discharge capacity after 100 cycles is 130.50 mAh / g, and the capacity retention rate is 75.36% in the voltage range of 2.75V-4.35V at 25°C and 1C rate.

[0099] Example 5

[0100] The difference from Example 4 is that the doping element in the positive electrode material is boron element, and in the formed product, the B and W elements account for 0.05wt% and 0.1wt% of LiNi 0.83 Co 0.12 Mn 0.05The weight percentage of O2 (lithium transition metal oxide removing tungsten element and doping element) is 0.1wt%, 0.1wt% respectively, the final product is recorded as W-0.1 / B-0.1, the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c B a W c ]O2, wherein a=8.6x10 -3 , c=5.04x10 -4 .

[0101] The first cycle discharge capacity is 185.20mAh / g, the discharge capacity after 100 cycles is 129.64mAh / g, and the capacity retention rate is 70.0% in the voltage range of 2.75V-4.35V at 25°C and 1C rate.

[0102] Example 6

[0103] The difference from Example 4 is that the doping element in the positive electrode material is boron element, and in the product, B and W elements account for LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) is 0.5wt%, 0.1wt% respectively, the final product is recorded as W-0.1 / B-0.5, the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c B a W c ]O2, wherein a=4.30x10 -2 , c=5.04x10 -4 .

[0104] The first cycle discharge capacity is 181.21mAh / g, the discharge capacity after 100 cycles is 123.86mAh / g, and the capacity retention rate is 68.35% in the voltage range of 2.75V-4.35V at 25°C and 1C rate.

[0105] Example 7

[0106] The difference from Example 2 is that the doping element in the positive electrode material is boron element, and in the product, B and W elements account for LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) is 0.4wt%, 0.1wt% respectively, the final product is recorded as W-0.1 / B-0.4, the general formula is Li[(Ni 0.83 Co0.12 Mn 0.05 ) 1-a-c B a W c ]O2, wherein a = 3.44 x 10 -2 , c = 5.04 x 10 -4 .

[0107] The first cycle discharge capacity is 194.55 mAh / g, the discharge capacity after 100 cycles is 153.38 mAh / g, and the capacity retention rate is 78.83% in the voltage range of 2.75V-4.35V at 25°C, 1C rate.

[0108] Example 8

[0109] The difference from Example 4 is that the calcination temperature is 1000°C.

[0110] The first cycle discharge capacity is 152 mAh / g, the discharge capacity after 100 cycles is 98.80 mAh / g, and the capacity retention rate is 65% in the voltage range of 2.75V-4.35V at 25°C, 1C rate.

[0111] Example 9

[0112] The difference from Example 4 is that the doping elements are Sr and B, and the W, Sr and B elements account for 0.05wt%, 0.2wt%, 0.1wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (remove tungsten element and doping element lithium transition metal oxide) is 0.05wt%, 0.2wt%, 0.1wt%, and the product formed is recorded as W-0.05 / B-0.1 / Sr-0.2, the doping elements are Sr and B, the weight ratio is 2:1, and the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-b-c B a Sr b W c ]O2, wherein a = 8.6 x 10 -3 , b = 2.10 x 10 -3 , c = 2.52 x 10 -4 .

[0113] The first cycle discharge capacity is 183.43 mAh / g, the discharge capacity after 100 cycles is 156.50 mAh / g, and the capacity retention rate is 85.32% in the voltage range of 2.75V-4.35V at 25°C, 1C rate.

[0114] Example 10

[0115] The difference from Example 4 is that the doping elements are Zr and B. In the formed product, the W, Zr and B elements account for LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) is 0.05wt%, 0.2wt%, 0.1wt%, and the finally formed product is recorded as W-0.05 / B-0.1 / Zr-0.2, the weight ratio of Zr and B is 2:1, and the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-b-c B a Zr b W c ]O2, wherein a = 8.6 x 10 -3 , b = 2.04 x 10 -3 , and c = 2.52 x 10 -4 .

[0116] The first cycle discharge capacity is 184.33mAh / g, the discharge capacity after 100 cycles is 153.20mAh / g, and the capacity retention rate is 83.11% in the voltage range of 2.75V-4.35V at 25℃ and 1C rate.

[0117] Example 11

[0118] The difference from Example 4 is that the doping elements are Sr and Zr. In the formed product, the W, Sr and Zr elements account for LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) is 0.05wt%, 0.2wt%, 0.2wt%, and the finally formed product is recorded as W-0.05 / B-0.2 / Zr-0.2, the weight ratio of Zr and B is 1:1, and the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-b-c Sr a Zr b W c ]O2, wherein a = 2.10 x 10 -3 , b = 2.04 x 10 -3 , and c = 2.52 x 10 -4 .

[0119] The first cycle discharge capacity is 186.20mAh / g, the discharge capacity after 100 cycles is 166.31mAh / g, and the capacity retention rate is 89.32% in the voltage range of 2.75V-4.35V at 25℃ and 1C rate.

[0120] Example 12

[0121] The difference from Example 3 is that the doping element is Zr. In the formation product, the W and Zr elements respectively account for 0.05wt% and 0.35wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) is 0.05wt%, 0.35wt%, and the finally formed product is recorded as W-0.05 / Zr-0.35, and the finally formed product is W-0.05 / Zr-0.35, and the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c Zr a W c ]O2, wherein a = 3.57 x 10 -3 , c = 2.52 x 10 -4 .

[0122] In the voltage range of 2.75V-4.35V at 25°C, 1C rate, the first cycle discharge capacity is 185.00mAh / g, and the discharge capacity after 100 cycles is 144.67mAh / g, and the capacity retention rate is 78.20%.

[0123] Example 13

[0124] The difference from Example 3 is that the doping element is Zr. In the formation product, the W and Zr elements respectively account for 0.05wt% and 0.35wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) is 0.05wt%, 0.2wt%, and the finally formed product is recorded as W-0.05 / Zr-0.2, and the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c Zr a W c ]O2, wherein a = 2.04 x 10 -3 , c = 2.52 x 10 -4 .

[0125] In the voltage range of 2.75V-4.35V at 25°C, 1C rate, the first cycle discharge capacity is 187.33mAh / g, and the discharge capacity after 100 cycles is 152.15mAh / g, and the capacity retention rate is 81.22%.

[0126] Example 14

[0127] The difference from Example 3 is that the doping element is Zr. In the product formed, the W and Zr elements account for 0.60wt% and 0.60wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2(removing tungsten element and lithium transition metal oxide of doping element) 0.05wt%, 0.60wt%, the final product is recorded as W-0.05 / Zr-0.60, the general formula is Li[(Ni 0.83 Co 0.12 Mn 0.05 ) 1-a-c Zr a W c ]O2, where a=6.12x10 -3 , c=2.52x10 -4 .

[0128] In the voltage range of 2.75V-4.35V at 25°C and 1C rate, the discharge capacity of the first cycle is 182.45mAh / g, the discharge capacity of the 100th cycle is 139.85mAh / g, and the capacity retention rate is 76.65%.

[0129] Example 15

[0130] The difference from Example 4 is that the heating rate of the heat preservation calcination process is 3°C / min.

[0131] In the voltage range of 2.75V-4.35V at 25°C and 1C rate, the discharge capacity of the first cycle is 178.00mAh / g, the discharge capacity of the 100th cycle is 125.40mAh / g, and the capacity retention rate is 70.45%.

[0132] Example 16

[0133] The difference from Example 4 is that the heating rate of the heat preservation calcination process is 1°C / min.

[0134] In the voltage range of 2.75V-4.35V at 25°C and 1C rate, the discharge capacity of the first cycle is 180.22mAh / g, the discharge capacity of the 100th cycle is 148.16mAh / g, and the capacity retention rate is 82.21%.

[0135] Example 17

[0136] The difference from Example 4 is that the heating rate of the heat preservation calcination process is 4°C / min.

[0137] In the voltage range of 2.75V-4.35V at 25°C and 1C rate, the discharge capacity of the first cycle is 168.30mAh / g, the discharge capacity of the 100th cycle is 114.78mAh / g, and the capacity retention rate is 68.20%.

[0138] Comparative Example 1

[0139] The difference from Example 1 is that, in the formation of the product, the Sr and W elements account for 1wt% and 0.1wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) are 1wt%, 0.1wt% respectively, and the final product is recorded as W-0.1 / Sr-1.

[0140] In the voltage range of 2.75V-4.35V at 25℃, 1C rate, the first cycle discharge capacity is 165.72mAh / g, the discharge capacity after 100 cycles is 111.50mAh / g, and the capacity retention rate is 67.28%.

[0141] Comparative Example 2

[0142] The difference from Example 4 is that, in the formation of the product, the B and W elements account for 0.02wt% and 0.8wt% of LiNi 0.83 Co 0.12 Mn 0.05 O2 (lithium transition metal oxide removing tungsten element and doping element) are 0.02wt%, 0.8wt% respectively, and the final product is recorded as W-0.02 / B-0.8.

[0143] In the voltage range of 2.75V-4.35V at 25℃, 1C rate, the first cycle discharge capacity is 155.63mAh / g, the discharge capacity after 100 cycles is 97.80mAh / g, and the capacity retention rate is 64.33%.

[0144] From the above description, it can be seen that the above-mentioned examples of the present application achieve the following technical effects:

[0145] From Examples 1, 3 and 4, it can be seen that, under the same conditions, compared with zirconium element and boron element, the comprehensive performance of the positive electrode material doped with strontium element is more excellent.

[0146] Comparing Examples 1, 2 and Comparative Example 1, it can be seen that limiting the weight ratio of lithium nickel cobalt manganese composite positive electrode material, tungsten element and strontium element within the preferred range of the present application is beneficial to improve the comprehensive performance of the positive electrode material.

[0147] Comparing Examples 3, 13 and 14, it can be seen that limiting the weight ratio of lithium nickel cobalt manganese composite positive electrode material, tungsten element and zirconium element within the preferred range of the present application is beneficial to improve the comprehensive performance of the positive electrode material.

[0148] Comparing Examples 4 to 7 and Comparative Example 2, it can be seen that limiting the weight ratio of lithium nickel cobalt manganese oxide composite cathode material, tungsten, and boron to the preferred range of this application is beneficial to improving the overall performance of the cathode material.

[0149] Comparing Examples 4, 15, 16 and 17, it can be seen that limiting the heating rate of the calcination process to the preferred range of this application is beneficial to improving the overall performance of the cathode material.

[0150] Comparing Examples 1 to 11 and Comparative Examples 1 to 2, it can be seen that the overall performance of the lithium nickel cobalt manganese oxide composite cathode material provided in this application is far superior to that of existing cathode materials.

[0151] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a lithium nickel cobalt manganese oxide composite cathode material, characterized in that, The lithium nickel cobalt manganese oxide composite cathode material is a lithium transition metal oxide containing tungsten and doping elements, wherein the doping element is strontium, or a mixture of strontium and boron, and the lithium nickel cobalt manganese oxide composite cathode material is single crystal particles and / or single crystal particle agglomerates. When the dopant element is strontium, the strontium content is 0.08 to 0.5 wt%, calculated as the weight percentage of lithium transition metal oxides (excluding tungsten and dopant elements) in the lithium nickel cobalt manganese oxide composite cathode material; the weight ratio of tungsten to strontium is 1:0.5 to 1:

2. When the dopant element is a mixture of strontium and boron, the total content of the dopant element is 0.2 to 0.5 wt%, based on the weight percentage of lithium transition metal oxides (excluding tungsten and dopant elements) in the lithium nickel cobalt manganese oxide composite cathode material; the weight ratio of tungsten to each dopant element is 1:(1 to 4); and the weight ratio of tungsten to the total weight of the dopant elements is 1:(4 to 8). The preparation method of the lithium nickel cobalt manganese oxide composite cathode material includes: Nickel cobalt manganese oxide precursor, doping raw material, tungsten source and lithium source are mixed in a predetermined ratio and calcined at a constant temperature to obtain the nickel cobalt manganese oxide lithium composite cathode material. The doping raw material is used to provide one or more of the required strontium and boron elements. said nickel cobalt manganese oxide precursor is represented by Ni 0.83 Co 0.12 Mn 0.05 (OH)2, and a molar ratio of said nickel cobalt manganese hydroxide precursor to said lithium source is 1:(1-1.05); During the formulation process, when the dopant element is strontium, the weight ratio of the lithium transition metal oxide (excluding tungsten and the dopant element), the amount of tungsten added, and the amount of strontium added in the lithium nickel cobalt manganese oxide composite cathode material is 100:(0.05~0.4):(0.1~0.5). During the formulation process, when the dopant element is a mixture of strontium and boron, the weight ratio of the lithium transition metal oxide (excluding tungsten and dopant elements), the amount of tungsten added, the amount of strontium added, and the amount of boron added in the lithium nickel cobalt manganese oxide composite cathode material is 100:(0.05~0.4):(0.1~0.4):(0.1~0.4). The tungsten source is selected from one or more of the group consisting of tungsten trioxide, phosphotungstic acid and ammonium metatungstate; The raw materials for the strontium element are one or more of the group consisting of strontium oxide and strontium carbonate; The raw material for the boron element is selected from one or more of the group consisting of boric acid, boron oxide and sodium tetraborate; The calcination temperature is 800–900℃, the holding time is 12–18 h, and the heating rate is 0.8–3℃ / min.

2. The method of claim 1, wherein the lithium nickel cobalt manganese oxide composite cathode material is prepared by the steps of: mixing a lithium source, a nickel source, a cobalt source, and a manganese source to form a mixture; and calcining the mixture at a temperature of 700-900°C for 5-20 hours. When the doping element is a mixture of strontium and boron, the total content of the doping element is 0.25 to 0.4 wt%, calculated as the weight percentage of lithium transition metal oxides excluding tungsten and the doping element in the lithium nickel cobalt manganese oxide composite cathode material.

3. The method for preparing the lithium nickel cobalt manganese oxide composite cathode material according to claim 1 or 2, characterized in that, When the doping element is a mixture of strontium and boron, the weight ratio of the tungsten element to the total weight of the doping elements is 1:(5.5~8).

4. The method of claim 1 or 2, wherein the lithium nickel cobalt manganese oxide composite cathode material is prepared by the steps of: preparing a lithium nickel cobalt manganese oxide precursor; and coating the lithium nickel cobalt manganese oxide precursor with a lithium source. The nickel-cobalt-lithium manganate composite positive electrode material adopts the following general formula: Li[(Ni x Co y Mn z ) 1-a-b-c L a M b W c ]O2, wherein 0.6≤x<1, 0<y<1, 0<z<1, x+y+z=1, L and M are independently selected from the doping elements, the values of a and b are 0-0.05, and a and b are not 0 at the same time, the value of c is 2x10 -4 ~0.

002.

5. The method for preparing the lithium nickel cobalt manganese oxide composite cathode material according to claim 1, characterized in that, The average particle size of the nickel-cobalt-lithium manganate composite positive electrode material is 2-5 μm.

6. The preparation method of the nickel-cobalt-lithium manganate composite positive electrode material according to claim 1 or 2, characterized in that, The heating rate of the heat preservation calcination process is 1-2.5 ℃ / min.

7. A lithium-ion battery comprising a positive electrode material, characterized in that, The positive electrode material is prepared by the preparation method of the nickel-cobalt-lithium manganate composite positive electrode material according to any one of claims 1-6.

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