Cathode material and method for manufacturing the same, lithium-ion battery

Abstract

The present invention relates to the field of lithium-ion batteries, and discloses a cathode material, a method for manufacturing the same, and a lithium-ion battery. The cathode material is Li 1+a (Ni x Co y Mn z G b )T c O2, where 0.02 ≦ a ≦ 0.1, 0.6 ≦ x ≦ 1, 0 < y ≦ 0.5, 0 < z ≦ 0.5, 0 < b ≦ 0.02, 0 < c ≦ 0.02, and at 45 °C, the (003) characteristic peak around 80 cycles satisfies the relationship of 0° ≦ ΔP = P 前 -P 後 ≦ 0.2°. The cathode material has high particle strength and further excellent crystal structure stability, and the cycle performance of the cathode material is significantly improved.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This invention claims priority and rights to patent application number 202410244850.X, filed with the China National Intellectual Property Administration on March 4, 2024, which is incorporated herein by reference in its entirety.

[0002] This invention relates to the technical field of lithium-ion batteries, and more specifically to positive electrode materials, methods for manufacturing the same, and lithium-ion batteries. [Background technology]

[0003] In recent years, as the new energy vehicle industry has grown worldwide, lithium-ion batteries have attracted attention due to their advantages such as high energy density and excellent cycle performance. Ternary materials (Ni-Co-Mn materials) are particularly widely used due to their advantages of high energy density and excellent low-temperature performance. In response to the demand for even higher energy density, two development directions, high nickel content and high voltage, have already become mainstream. However, the current challenges in both high nickel content and high voltage are mainly that, after increasing nickel content or voltage, the structural stability of the material deteriorates, leading to poor cycle stability of ternary materials and increased gas generation.

[0004] Regarding the issue of structural stability, currently, as the main means, measures such as adjusting the internal structure of materials, bulk doping, and surface coating are being used to try to improve. For example, Patent Document 1 (Chinese Patent No. 108598379 Specification) discloses a lithium nickel cobalt aluminum composite material coated with lithium tungstate and its manufacturing method, as well as applications. After dispersing a nickel cobalt aluminum precursor in a lithium-containing solution, tungsten trioxide is further added, and the lithium-containing solution reacts with tungsten trioxide to generate Li2WO4. In the process of evaporation crystallization, Li2WO4 is directly deposited on the nickel cobalt aluminum precursor and coated, and by performing sintering of lithium mixing, LiNi 0.8 Co 0.15 Al 0.05 O2@Li2WO4 can be obtained, and it is also disclosed that according to the deposition and coating formed by such a mixture reaction, a very uniform coating layer can be formed. However, the cathode material manufactured by this method has good doping and coating effects, but its process is complex, the filtrate recovery process is also complex, and the cost is high.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to overcome the problems existing in the prior art that the particle strength of the cathode material is low and the crystal structure stability is poor, the purpose of the present invention is to provide a cathode material, its manufacturing method, and a lithium-ion battery. The cathode material has a small peak change value of the (003) characteristic peak after 80 cycles at 45 °C, indicating that it has high particle strength and further excellent crystal structure stability, and the cycle performance of the cathode material is significantly improved.

Means for Solving the Problems

[0006] In order to achieve the above object, in the first aspect of the present invention, it has a composition shown in Formula I, Li1+a (Ni x Co y Mn z G b )T c O₂ (Formula I) Where 0.02 ≤ a ≤ 0.1, 0.6 ≤ x ≤ 1, 0 < y ≤ 0.5, 0 < z ≤ 0.5, 0 < b ≤ 0.02, 0 < c ≤ 0.02, G is at least one selected from Al, Y, Zr, Ti, Ca, V, Nb, Ta, Co, W, Er, La, Sb, Mg, Sr, Sn, Mn, Mo, Ce, F, B, and P, and T is at least one selected from Al, Sr, Si, Nb, Co, W, Ti, Zr, Ce, Mn, F, B, and P, At 45 °C measured by XRD (X-ray diffraction method), the (003) characteristic peak before and after 80 cycles is 0° ≤ ΔP = P 前 -P 後 ≤ 0.2°, where P 前 is the peak position of the (003) characteristic peak before the cycle, and P 後 is the peak position of the (003) characteristic peak after 80 cycles, providing a cathode material. <000009​​​​​​​​​​​​(5) The step of mixing the secondary sintered material IV with an additive containing element T to obtain a homogeneous mixture V, (6) The process includes the step of obtaining the positive electrode material by performing a third sintering of the mixture V in an oxygen-containing atmosphere, setting the constant temperature to T3 and the constant temperature time to t3, and then crushing and sieving the mixture after sintering, or by directly sieving the mixture. Here, the precursor is selected from nickel cobalt manganese oxide and / or nickel cobalt manganese hydroxide, and the amounts of the lithium source and the precursor used are n(Li):[n(Ni)+n(Co)+n(Mn)+n(G)]=1.02~1.10:1. At least one of the additives containing element C1 and the additive containing element C2 is added.

[0008] A third aspect of the present invention provides a lithium-ion battery containing the above-described positive electrode material. [Effects of the Invention]

[0009] According to the above technical proposal, the positive electrode material, its manufacturing method, and lithium-ion battery provided by the present invention offer the following beneficial effects. The cathode material in this invention exhibits a small peak change in the (003) characteristic peak after 80 cycles at 45°C. This demonstrates that the cathode material possesses high particle strength and excellent crystal structure stability, contributing to improved Li-ion transport and cycle performance. When this cathode material is applied to a lithium-ion battery, a high discharge capacity is obtained while simultaneously ensuring a high capacity retention rate.

[0010] Furthermore, since the cathode material in the present invention exhibits a low rate of change in lattice volume when the SOC is different, the particle strength and crystal structure stability of the cathode material are further improved, resulting in further improvements in the discharge capacity and capacity retention rate of the lithium-ion battery. The manufacturing method provided by the present invention ensures that the precursor and lithium source react uniformly by preparing a specific amount of lithium additive and performing three sintering steps, and also ensures that the additive elements G (C1 and / or C2) and T can play their appropriate roles at specific temperatures. The manufacturing method provided by the present invention allows the elements to perform their roles better, reduces the residual alkali content on the surface, and improves the particle strength and structural stability of the manufactured cathode material. Furthermore, by controlling the temperature during the three sintering processes to meet specific conditions, different elements can be positioned at different locations within the material. For example, at high temperatures, they can enter the core of the material; at the next high temperature, they can enter the shallow layers; and at low temperatures, they can adhere to the surface of the material. This improves multidimensional particle strength and structural stability from the inside to the surface of the material. [Brief explanation of the drawing]

[0011] The above and / or additional aspects and advantages of the present invention will become clearer and easier to understand by describing the embodiments with reference to the accompanying drawings, as follows. [Figure 1] This figure shows the peak position of (003) measured by an XRD diffractometer before and after the cycle of the cathode material in Example 1. [Figure 2] This figure shows the peak position of (003) measured by an XRD diffractometer before and after the cycle of the cathode material in Comparative Example 1. [Figure 3] This is a cross-sectional EDS analysis diagram of the cathode material in Example 4. [Figure 4] This is a comparison of the cycle performance of lithium-ion batteries obtained by assembling the positive electrode materials in Example 1 and Comparative Example 1. [Modes for carrying out the invention]

[0012] The endpoints and any values within the scope disclosed in this specification are not limited by the precise scope or value, and these scopes or values should be understood to include values close to these scopes or values. For numerical ranges, between the endpoint values of each range, between the endpoint value of each range and the value of a single point, and between the values of single points, they may be combined with each other to obtain one or more new ranges of values. These numerical ranges may be regarded as specifically disclosed in this specification.

[0013] In the first aspect of the present invention, it has a composition represented by Formula I, Li 1+a (Ni x Co y Mn z G b )T c O2 (Formula I) where 0.02 ≦ a ≦ 0.1, 0.6 ≦ x ≦ 1, 0 < y ≦ 0.5, 0 < z ≦ 0.5, 0 < b ≦ 0.02, 0 < c ≦ 0.02, G is at least one selected from Al, Y, Zr, Ti, Ca, V, Nb, Ta, Co, W, Er, La, Sb, Mg, Sr, Sn, Mn, Mo, Ce, F, B, and P, and T is at least one selected from Al, Sr, Si, Nb, Co, W, Ti, Zr, Ce, Mn, F, B, and P, At 45°C measured by XRD, the (003) characteristic peak before and after 80 cycles is 0° ≦ △P = P 前 -P 後 ≦ 0.2°, where P 前 is the peak position of the (003) characteristic peak before cycling, and P 後 is the peak position of the (003) characteristic peak after 80 cycles, and a positive electrode material is provided characterized by this.

[0014] In this invention, the positive electrode material exhibits a small peak change in the (003) characteristic peak after 80 cycles at 45°C. This demonstrates that the positive electrode material possesses high particle strength and excellent crystal structure stability, contributing to improved Li ion transport and cycle performance. In particular, when the positive electrode material contains Li in an appropriate amount, applying it to a lithium-ion battery results in high discharge capacity while simultaneously ensuring high capacity retention.

[0015] In this invention, the peak change value of the (003) characteristic peak of the cathode material after 80 cycles at 45°C is measured by the following method.

[0016] The positive electrode material described above is manufactured into a lithium-ion battery by a general method. Specifically, the lithium-ion battery includes a positive electrode tab, a negative electrode tab, an electrolyte and separator located between the positive and negative electrode tabs.

[0017] The positive electrode tab includes a positive electrode current collector and a positive electrode material layer located on the positive electrode current collector, the positive electrode material layer including the positive electrode material, an adhesive, and a conductive agent.

[0018] Here, the adhesive for the positive electrode material layer is a common choice in the battery field, and its type and content are not specifically limited. It may include, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), vinylidene fluoride copolymers, or modified derivatives thereof (e.g., modified by carboxylic acids, acrylic acids, acrylonitrile, etc.).

[0019] The conductive agent in the positive electrode material layer is a common choice in the battery field, and its type and content are not specifically limited. It may include, but is not limited to, a combination of one or more of the following: acetylene black, conductive carbon black, carbon fiber (VGCF), carbon nanotubes (CNT), Ketjenblack, etc.

[0020] Here, the positive electrode current collector may typically be a layered structure. The positive electrode current collector is typically a structure or component capable of collecting current, and the positive electrode current collector may be made of various materials used as positive electrode current collectors in electrochemical energy storage devices in the industry. For example, the positive electrode current collector may, but is not limited to, metal foil; more specifically, it may, but is not limited to, nickel foil or aluminum foil.

[0021] The negative electrode tab comprises a negative electrode current collector and a negative electrode active material layer located on the surface of the negative electrode current collector, the negative electrode active material layer typically comprises a negative electrode active material. The negative electrode active material is a common choice in the battery field, and its type and content are not specifically limited, and may include, but are not limited to, a combination of one or more of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium titanate, or other metals capable of forming alloys with lithium.

[0022] Here, the graphite may be one or more combinations selected from artificial graphite, natural graphite, and modified graphite. The silicon-based material may be one or more combinations selected from elemental silicon, silicon-oxygen compounds, silicon-carbon composites, and silicon alloys. The tin-based material may be one or more combinations selected from elemental tin, tin-oxygen compounds, and tin alloys.

[0023] Here, the negative electrode current collector is typically a structure or component that collects electric current, and the negative electrode current collector may be made of various materials used as positive electrode current collectors in lithium secondary batteries in this industry. For example, the negative electrode current collector may include, but is not limited to, metal foil; more specifically, it may include, but is not limited to, copper foil. The negative electrode tab may also be a lithium tab.

[0024] Separators are a common choice in the battery field, and their type and content are not specifically limited. They may include, but are not limited to, a combination of one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers.

[0025] The electrolyte is a common choice in the battery field, and its type and content are not specifically limited. It may be any type of electrolyte applicable to lithium secondary batteries in this industry. For example, the electrolyte typically comprises an electrolyte and a solvent, and the electrolyte typically comprises a lithium salt. More specifically, the lithium salt may be an inorganic lithium salt and / or an organic lithium salt. Specifically, it may include, but is not limited to, a combination of one or more of LiPF6, LiBF4, LiN(SO2F)2 (abbreviated as Li FSI), LiN(CF3SO2)2 (abbreviated as Li TFSI), LiClO4, LiAsF6, LiB(C2O4)2 (abbreviated as LiBOB), and LiBF2C2O4 (abbreviated as LiDFOB).

[0026] A portion of the manufactured batteries were subjected to 80 full charge-discharge cycles at 45°C with a current of 1C. Finally, the uncycled and cycled electrode tabs were disassembled, cleaned, and then the full spectrum was measured using an XRD diffractometer. Because the crystal structure changes before and after the cycle, the XRD peak positions shift due to synchronization. The peak positions of the (003) characteristic peak before and after the cycle were respectively identified as P 前 and P 後 It is named as such, and the change in peak position is △P = P 前 -P 後 This indicates that the larger ΔP is, the worse the crystal structure stability of the cathode material becomes during the cycling process.

[0027] In this invention, in addition to the element Li, elements Ni, Co, Mn, and G are distributed both inside and on the surface of the cathode material particles, and element T is distributed on the surface of the cathode material particles.

[0028] In the present invention, element T in the positive electrode material is the main element of the coating, and the coating includes an oxide containing element T, and may further contain at least one element from the substrate, Ni, Co, Mn, and G.

[0029] In this invention, in formula I, a may be in the range of 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 and any two of these values, x may be in the range of 0.6, 0.7, 0.008, 0.9, 1 and any two of these values, and y may be 0.01, 0.05, 0.1, 0.15, 0 The range of z may be 0.20, 0.25, 0.30, 0.35, 0.40, 0.4, 0.50 and any two of those values, and the range of b may be 0.01, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.4, 0.50 and any two of those values, and b may be 0.001, 0.0015, 0. c may be a range consisting of 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, 0.0080, 0.0085, 0.0090, 0.0095, 0.010, 0.015, 0.02 and any two values, where c is 0.001, 0. The range may consist of 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.005, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, 0.0080, 0.0085, 0.0090, 0.0095, 0.010, 0.015, 0.02, and any two of these values.

[0030] Furthermore, 0.03≦a≦0.07, 0.6≦x≦1, 0 <y≦0.5、0<z≦0.5、0.005≦b≦0.015、0.002≦c≦0.015とする。

[0031] Furthermore, G is at least one selected from Al, Ti, Co, Sr, Ce, F, Y, Zr, W, and La, and T is at least one selected from B, Al, Si, W, and F.

[0032] In this invention, ΔP may be within the range of 0°, 0.01°, 0.02°, 0.03°, 0.04°, 0.05°, 0.06°, 0.07°, 0.08°, 0.09°, 0.10°, 0.11°, 0.12°, 0.13°, 0.14°, 0.15°, 0.16°, 0.17°, 0.18°, 0.19°, 0.2°, and any two of these values.

[0033] Furthermore, let 0° ≤ △P ≤ 0.1°.

[0034] In this invention, in formula I, y and z represent only the Co or Mn content from the precursor (nickel-cobalt-manganese oxide and / or nickel-cobalt-manganese hydroxide) in the positive electrode material. When G contains Co and / or Mn, b is denoted as the sum of the Co or Mn content as element G and the content of other elements G.

[0035] Specifically, when G contains Co and / or Mn, the positive electrode material has the composition shown in formula II. Li 1+a (Ni x Co' y Mn' z Co ’’d Mn ’’e G f )T c O2 (formula I) Here, 0.02 ≤ a ≤ 0.1, 0.6 ≤ x ≤ 1, 0 <y≦0.5、0<z≦0.5、0<d+e+f=b≦0.02、0<c≦0.02であり、 G is at least one selected from Al, Y, Zr, Ti, Ca, V, Nb, Ta, W, Er, La, Sb, Mg, Sr, Sn, Mo, Ce, F, B, and P, and T is at least one selected from Al, Sr, Si, Nb, Co, W, Ti, Zr, Ce, Mn, F, B, and P. Here, Co' and Mn' are from the precursor, and Co'' and Mn'' are from the doped element, and the content of Co (or Mn) from the precursor and Co (or Mn) as element G in the cathode material is calculated by the amount added during the manufacturing process of the cathode material.

[0036] According to the present invention, the lattice volume V of the cathode material in the cases of 0%SOC, 50%SOC, and 100%SOC, as measured by XRD, 0%≦△V 50% =(V 50 -V0) / V0 ≤ 10%, and / or 0% ≤ △V 100% =(V 100 The relationship -V0) / V0 ≤ 15% is satisfied, Here, V0 is the lattice volume of the positive electrode material in the case of 0% SOC, and V 50 This is the lattice volume of the cathode material in the case of 50% SOC, and V 100 This is the lattice volume of the cathode material in the case of 50% SOC.

[0037] In this invention, it has been shown that when the above relationship is satisfied, the lattice volume V of the positive electrode material when the SOC is different, the positive electrode material exhibits a low rate of change in lattice volume during the charging process. Furthermore, it has been shown that the positive electrode material has high particle strength and excellent crystal structure stability, thereby further improving the discharge capacity and capacity retention rate of the lithium-ion battery.

[0038] In this invention, the lattice volume V of the positive electrode material in the case of SOC is measured by the following method: The positive electrode material is manufactured into a battery according to an appropriate formulation, then charged to 0% SOC, 50% SOC, and 100% SOC, respectively, and finally the corresponding battery is disassembled, the electrode tabs are cleaned, and then measured using an XRD diffractometer.

[0039] In the present invention, △V50% may be in the range of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and any two values, and △V100% may be in the range of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, and any two values.

[0040] Furthermore, 0%≦△V 50% Let's assume the percentage is ≤5%.

[0041] Furthermore, 0%≦V 100% Let's assume it's ≤ 10%.

[0042] According to the present invention, the specific surface area SSA of the positive electrode material before and after pressure application is The relationship 0% ≤ △SSA% = (SSA4 - SSA0) / SSA0 ≤ 80% is satisfied, where SSA0 is the specific surface area of ​​the positive electrode material before pressure is applied, and SSA4 is the specific surface area of ​​the positive electrode material after being subjected to a pressure of 4.5 tons.

[0043] The rate of change in the specific surface area of ​​the positive electrode material before and after pressure application can reflect the particle strength of the positive electrode material itself, and it has been shown that the larger the △SSA%, the worse the particle strength of the positive electrode material. In the present invention, since the rate of change in the specific surface area of ​​the positive electrode material before and after pressure application is low, it is shown that the particle strength of the positive electrode material itself is high.

[0044] In this invention, the specific surface area of ​​the positive electrode material before and after pressure application is measured by the following method. Using an MCP-PD51 tester, a pressure of 4.5 tons is applied to the positive electrode material, which is then polished using a mortar and pestle, sieved through a 300-mesh sieve, and the powder at that pressure is obtained and tested for specific surface area. The specific surface areas of the positive electrode material before and after pressure application are SSA0 and SSA4, respectively, and the specific surface area increase rate is ΔSSA%. The formula for calculating the specific surface area increase rate is ΔSSA% = (SSA4 - SSA0) / SSA0.

[0045] In this invention, △SSA% may be in the range of 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, and any two values.

[0046] Furthermore, we assume that 0 ≤ △SSA% ≤ 50%.

[0047] According to the present invention, the median diameter of the positive electrode material is 2 μm to 20 μm, and may be in the range of, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm and any two values, and is preferably 3 μm to 18 μm.

[0048] According to the present invention, the residual alkali content of the positive electrode material is 0 ppm to 10,000 ppm, for example, 0 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1200 ppm, 1400 ppm, 1600 ppm, and 1800 ppm. The range may be 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm, 8500 ppm, 9000 ppm, 9500 ppm, 10000 ppm, and any two values, preferably 1000 ppm to 8000 ppm.

[0049] In this invention, the residual lithium includes lithium carbonate and / or lithium hydroxide.

[0050] A second aspect of the present invention provides a method for manufacturing the above-described positive electrode material, wherein the manufacturing method is (1) A step of physically mixing a precursor, a lithium source, and an additive containing a selective C1 element to obtain a homogeneous mixture I, (2) In an oxygen-containing atmosphere, perform a first sintering on mixture I, setting the constant temperature to T1 and the constant temperature time to t1, and after sintering, crush and sift, or sift directly, to obtain primary sintered material II. (3) The step of mixing the primary sintered material II with a selective C2 element-containing additive to obtain a homogeneous mixture III, (4) In an oxygen-containing atmosphere, a second sintering is performed on mixture III, with a constant temperature of T2 and a constant temperature time of t2, and after sintering, the mixture is crushed and sieved, or directly sieved, to obtain secondary sintered material IV. (5) The step of mixing the secondary sintered material IV with an additive containing element T to obtain a homogeneous mixture V, (6) The process includes the step of obtaining the positive electrode material by performing a third sintering of the mixture V in an oxygen-containing atmosphere, setting the constant temperature to T3 and the constant temperature time to t3, and then crushing and sieving the mixture after sintering, or by directly sieving the mixture. The precursor is selected from nickel cobalt manganese oxide and / or nickel cobalt manganese hydroxide, and the amounts used for the lithium source, the precursor, the C1 element-containing additive and the C2 element-containing additive in the positive electrode material are such that n(Li):[n(Ni)+n(Co)+n(Mn)+n(G)]=1.02~1.10:1. Herein, at least one of the additives containing element C1 and the additive containing element C2 is added.

[0051] In the present invention, the manufacturing method ensures that the precursor and lithium source react uniformly by preparing a specific amount of lithium additive and performing three sintering steps, and also ensures that the additives, elements G (C1 and / or C2) and T, can play their appropriate roles at specific temperatures, and also ensures that the lithium transfer rate of the cathode material is high. The manufacturing method provided by the present invention allows elements to perform their roles better, reduces residual alkali content on the surface, improves the particle strength and structural stability of the manufactured cathode material, and makes it possible to obtain a cathode material having the specific composition and structure described in the first aspect of the present invention.

[0052] In the present invention, the amounts used of the lithium source, the precursor, the C1 element-containing additive, and the C2 element-containing additive in the positive electrode material are such that n(Li):[n(Ni)+n(Co)+n(Mn)+n(G)] are in the range of 1.02:1, 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1, 1.09:1, 1.10:1, and any two values.

[0053] Furthermore, the amounts used for the lithium source, the precursor, the C1 element-containing additive, and the C2 element-containing additive are in the ratio n(Li):[n(Ni)+n(Co)+n(Mn)+n(G)]=1.03~1.07:1.

[0054] According to the present invention, the amounts used for the precursor, the C1-containing additive, and the C2-containing additive in the positive electrode material are 0 <n(G):[n(Ni)+n(Co)+n(Mn)+n(G)]≦0.02となる。

[0055] In this invention, by controlling the total amount of additives containing C1 element and C2 element to satisfy the above range, it is possible to contribute to the differentiated distribution of elements in the interior and shallow layers of the material, thereby improving the structural stability and particle strength of the material. As a result, batteries assembled with this positive electrode material can simultaneously possess good charge / discharge capacity and good circulation performance.

[0056] In this invention, the amounts of the C1-containing additive and the C2-containing additive used are not particularly limited, but it is sufficient that the total amount of both used satisfies the above range.

[0057] In the present invention, the amounts used for the precursor, the C1 element-containing additive, and the C2 element-containing additive in the positive electrode material are such that n(G):[n(Ni)+n(Co)+n(Mn)+n(G)] are in the range of 0.001, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, 0.0080, 0.0085, 0.0090, 0.0095, 0.010, 0.015, 0.02, and any two values.

[0058] Furthermore, the amounts used for the precursor, the C1-containing additive, and the C2-containing additive in the cathode material satisfy the following condition: 0.005 ≤ n(G): [n(Ni) + n(Co) + n(Mn) + n(G)] ≤ 0.015.

[0059] According to the present invention, the amount of the secondary sintered material and the T-element-containing additive used in the positive electrode material is 0 <n(T):[n(Ni)+n(Co)+n(Mn)+n(G)]≦0.02となる。

[0060] In this invention, by controlling the amount of T-element-containing additive used to satisfy the above range, a protective layer is formed on the surface of the material, further improving the surface stability and particle strength of the material.

[0061] In the present invention, the amount of the secondary sintered material and the additive containing element T used in the positive electrode material is such that n(T):[n(Ni)+n(Co)+n(Mn)+n(G)] is within the range of 0.001, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, 0.0080, 0.0085, 0.0090, 0.0095, 0.010, 0.015, 0.02, and any two values.

[0062] Furthermore, the amount of secondary sintered material and the additive containing element T used in the positive electrode material is such that 0.002 ≤ n(T):[n(Ni) + n(Co) + n(Mn) + n(G)] ≤ 0.015.

[0063] According to the present invention, C1 and C2 are each at least one individually selected from Al, Y, Zr, Ti, Ca, V, Nb, Ta, Co, W, Er, La, Sb, Mg, Sr, Sn, Mn, Mo, Ce, F, B, and P.

[0064] In preferred embodiments of the present invention, C1 is at least one selected from Al, Y, Zr, W, La, Sr, and Ce. The above-mentioned specific types of C1 elements contribute to further improvement of the crystal structure stability of the cathode material.

[0065] In another preferred embodiment of the present invention, C2 is at least one selected from Al, Ti, Co, Sr, Ce, and F. According to the above specific types of C2 elements, the residual alkali content on the surface of the cathode material can be further reduced, and the particle strength of the cathode material can be improved at the same time.

[0066] According to the present invention, T is at least one selected from Al, Sr, Si, Nb, Co, W, Ti, Zr, Ce, Mn, F, B, and P, and preferably at least one selected from B, Al, Si, W, and F.

[0067] In the present invention, the type of the lithium source is not particularly limited, and it may be lithium carbonate, hydrated lithium hydroxide or anhydrous lithium hydroxide.

[0068] In the present invention, the types of the additive containing C1 element, the additive containing C2 element and the additive containing T element are not particularly limited, and any substance that can provide C1 element, C2 element or T element may be used. For example, it may be an oxide, a hydroxide, or a carbonate.

[0069] According to the present invention, the constant temperature T1, the constant temperature T2, and the constant temperature T3 satisfy the relationship of 200°C ≤ T3 < T2 < T1 ≤ 1000°C.

[0070] In the present invention, by controlling the temperature of the third sintering so as to satisfy the above relationship, the structural stability of the positive electrode material can be further improved. Specifically, under the conditions of high temperature and high lithium ratio, the first sintering is carried out to sufficiently react the precursor, the lithium salt and the additive containing C1 element, so as to form a first sintered material with abundant bulk doping, improve the hardness and density of the positive electrode material, and improve the structural stability of the positive electrode material. By performing the second sintering at a relatively high temperature, the first sintered material and the additive containing C2 element can be formed into a second sintered material with a further doped surface, reduce the residual alkali on the surface, and improve the particle strength of the positive electrode material. By performing the third sintering at a low temperature, the additive containing T element can be coated on the surface of the particles to further improve the particle strength of the positive electrode material.

[0071] According to the present invention, 200°C ≤ T3 ≤ 500°C.

[0072] According to the present invention, 400°C ≤ T2 ≤ 900°C.

[0073] In the present invention, T3 may be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, or a range consisting of any two values.

[0074] In the present invention, T2 may be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, or a range consisting of any two values.

[0075] Furthermore, 250°C ≤ T3 < T2 < T1 ≤ 980°C, and 50°C ≤ T1 - T2 ≤ 300°C. For example, T1 - T2 may be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 150°C, 200°C, 250°C, 300°C, or a range consisting of any two values.

[0076] Furthermore, 250°C ≤ T3 ≤ 450°C.

[0077] Furthermore, 500°C ≤ T2 ≤ 800°C.

[0078] In the present invention, the constant temperature time t1 is 6 h to 18 h.

[0079] In the present invention, the constant temperature time t2 is 6 h to 14 h.

[0080] In the present invention, the constant temperature time t3 is 6 h to 12 h.

[0081] In the present invention, there are no particular requirements for the equipment used for crushing, as long as it can achieve crushing. For example, it may be one or more of a soymilk machine, jaw crusher, roller, rotary wheel mill, colloid mill, mechanical mill, and jet mill.

[0082] In the present invention, the oxygen-containing atmosphere is oxygen gas and / or air.

[0083] In the present invention, the residual alkali content of the secondary sintered material IV is 3000 ppm to 15000 ppm, and may be in the range of, for example, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm, 8500 ppm, 9000 ppm, 9500 ppm, 10000 ppm, 11000 ppm, 12000 ppm, 13000 ppm, 14000 ppm, 15000 ppm, and any two values, preferably 3000 ppm to 10000 ppm.

[0084] A third aspect of the present invention provides a lithium-ion battery containing the above-described positive electrode material.

[0085] The present invention will be described in detail below with reference to examples. The peak position and grid volume of the (003) characteristic peak of the cathode material are measured by XRD. The specific measurement conditions are: operating temperature: 21±5℃, humidity: ≤65%, cooling water circulation machine temperature: 23±1℃, water pressure: 0.36 MPa, refrigerant high pressure: 0.8~1.8 MPa, refrigerant low pressure: 0.4~0.7 MPa, scan speed: 5° / min, start angle: 10.0000, end angle: 90.0000; sampling W: 0.0200, and automatic rotary table rotation speed: 60° / min.

[0086] The specific surface area of ​​the cathode material is measured using a Tri-star 3020 specific surface meter manufactured by Micromeritics, Inc., USA. The specific measurement conditions are as follows: sample amount: 5.0 g, degassing time / temperature of the equipment: 100°C / 120 min (aeration purging), adsorbate: N2, 99.99%, liquid nitrogen temperature: -196°C, and multi-point BET method: P / P 0.060, 0.080, 0.120, 0.160, 0.200.

[0087] The median diameter of the cathode material is measured using a Malvern Mastersizer 3000 laser particle size analyzer. The specific measurement conditions are as follows: dispersant: 650 ml + 20 ml 5% sodium pyrophosphate; particle refractive index: 1.741; particle absorptivity: 1; solvent refractive index: Water / 1.330; total volume of particles and dispersant: about 800 mL; measurement cycle: 1 time; background measurement time: 5 s; stirrer / pump rotation speed: 2850 r / min; analysis mode: General purpose; light shielding degree: 14%~16%.

[0088] The residual alkali content of the cathode material and sintered material is measured using a Metrohm Omni Potentiometric Titrator manufactured by Metrohm GmbH of Switzerland. The specific measurement conditions are as follows: Take a 5g sample, add 95g of water, stir for 5 minutes, aspirate with 80mL and filter, and perform a test for residual alkali by potentiometric titration using 0.1 mol / L hydrochloric acid.

[0089] We will conduct electrochemical performance tests on coin-type batteries.

[0090] The battery was assembled as follows: 9.5 g of positive electrode active material sample, 0.25 g of acetylene black, and 0.25 g of polyvinylidene fluoride (PVDF) were taken, mixed, and a positive electrode slurry was formed. This positive electrode slurry was applied to aluminum foil and dried. It was then press-molded at a pressure of 100 MPa to a diameter of 12 mm and a thickness of 120 μm. After that, it was dried in a vacuum drying box at 120°C for 12 hours to obtain a positive electrode tab.

[0091] A Li metal tab with a diameter of 17 mm and a thickness of 1 mm is used as the negative electrode, a polyethylene porous membrane with a thickness of 25 μm is used as the separator, and a 1.0 mol / L LiPF6 solution with an equal mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) as the solvent is used as the electrolyte.

[0092] The positive electrode tab, separator, negative electrode tab, and electrolyte are assembled into a 2025 type coin cell.

[0093] The conditions for capacity measurement were as follows: A manufactured coin-cell battery sample was left standing for 24 hours. The battery sample was charged at a current density of 20 mA / g until the cutoff voltage reached 4.3 V. It was then charged at a constant voltage of 4.3 V for 30 minutes. After that, it was discharged at a current density of 20 mA / g until the cutoff voltage reached 3.0 V, and the discharge time was recorded.

[0094] Battery sample initial discharge ratio capacity = current density × discharge time.

[0095] For different states of charge (SOC), the following tests are performed: A manufactured coin cell battery sample was left standing for 24 hours. The battery sample was charged at a current density of 20 mA / g until the cutoff voltage reached 4.3V. It was then charged at a constant voltage of 4.3V for 30 minutes. Afterward, it was discharged at a current density of 20 mA / g until the cutoff voltage reached 3.0V, and the discharge time was recorded. Subsequently, the batteries were individually charged at a current density of 20 mA / g until they reached 3.73V and 4.30V, corresponding to 50% SOC and 100% SOC, respectively. Disassembly was then awaited. The conditions for the cycle test were as follows: The battery sample was charged and discharged twice at a current density of 20 mA / g until the cutoff voltage reached 3.0V to 4.3V, at which point activation was complete. Using the activated battery sample, a predetermined number of charge-discharge cycles (e.g., 80 times) were performed at a temperature of 45°C with a current density of 1C within the voltage range of 3.0V to 4.3V. As described above, the discharge ratio capacity per cycle can be obtained from the current density and the discharge time per cycle. The circulating performance of the battery sample is characterized by the high-temperature capacity retention rate, which is shown in Figure 4.

[0096] Here, the high-temperature capacity retention rate (%) = discharge ratio capacity at a predetermined number of 80 cycles / initial discharge ratio capacity × 100%.

[0097] To disassemble the battery, take it apart inside the glove compartment, remove the electrode tabs, wash them with DMC for 1 minute, dry them, and await testing.

[0098] All raw materials used in the examples and comparative examples are commercially available products.

[0099] Example 1 (1) Precursor (Ni 0.8 Co 0.1 Mn 0.1 Mixture I is obtained by physically mixing (OH)2, lithium hydroxide, Al2O3, and ZrO2 in a uniform manner. Here, the amounts of precursor, lithium hydroxide, Al2O3, and ZrO2 used in the positive electrode material are n(Li):[n(Ni)+n(Co')+n(Mn)+n(Al)+n(Zr)+n(Co')]=1.05, n(Al):[n(Ni)+n(Co')+n(Mn)+n(Al)+n(Zr)+n(Co')]=0.08, and n(Zr):[n(Ni)+n(Co')+n(Mn)+n(Al)+n(Zr)+n(Co')]=0.003.

[0100] (2) In an oxygen gas atmosphere, the mixture I is subjected to a first sintering, with a constant temperature of 790°C and a constant temperature time of 9 hours. After sintering, the mixture is directly sieved to obtain the primary sintered material II.

[0101] (3) The primary sintered material II and Co(OH)2 are mixed to obtain a homogeneous mixture III. Here, depending on the amount of Co(OH)2 added, the ratio of n(Co) in the positive electrode material becomes n(Co):[n(Ni)+n(Co')+n(Mn)+n(Al)+n(Zr)+n(Co'')]=0.108.

[0102] (4) A second sintering is performed on mixture III, with an oxygen gas atmosphere, a constant temperature of 700°C, and a constant temperature duration of 8 hours. After sintering, the mixture is directly sieved to obtain secondary sintered material IV.

[0103] (5) The secondary sintered material IV and boric acid are mixed in a ratio of [n(Ni)+n(Co)+n(Mn)+n(Al)+n(Zr)]:n(B)=1:0.005 to obtain a homogeneous mixture V.

[0104] (6) A third sintering is performed on mixture V, with an air atmosphere, a constant temperature of 350°C, and a constant temperature time of 8 hours. After sintering, the material is directly sieved to obtain the final cathode material, whose composition is Li 1.05 (Ni 0.783 Co' 0.098 Mn 0.098 Al 0.008 Zr 0.003 Co'' 0.010 )B 0.005 O2, where Co' is from the precursor, Co'' is from Co(OH)2, and after simplification, Li 1.05 (Ni 0.783 Co 0.108 Mn 0.098 Al 0.008 Zr 0.003 )B 0.005 It becomes O2.

[0105] Examples and Comparative Examples The cathode material is manufactured according to the method of Example 1. The specific manufacturing process parameters are shown in Table 1. [Table 1] [Table 2] [Table 3] [Table 4]

[0106] Table 2 shows the structural parameters of the cathode materials produced by the examples and comparative examples, and the performance indicators of the lithium-ion batteries assembled using the cathode materials in the examples and comparative examples. [Table 5] [Table 6]

[0107] As can be seen from Table 2, the cathode material manufactured by the present invention has characteristics such as high particle strength, low lattice volume change rate, and small change in peak value before and after cycles, and the lithium-ion battery manufactured by the present invention is also ensured to have a high discharge capacity and a high capacity retention rate.

[0108] Figure 1 shows the peak position of (003) measured by an XRD diffractometer around 80 cycles for the cathode material in Example 1, and Figure 2 shows the peak position of (003) measured by an XRD diffractometer around 80 cycles for the cathode material in Comparative Example 1. As can be seen from Figures 1 and 2, the degree of peak position displacement in Example 1 is smaller than the degree of peak position displacement in Comparative Example 1.

[0109] Figure 3 is a cross-sectional EDS analysis diagram of the cathode material in Example 4. As can be seen from Figure 3, the element Al is uniform within the material, and after secondary sintering, the Al and Co content in the shallow layers increases, indicating that the elements have entered the shallow layers of the material.

[0110] Figure 4 shows a comparison of the cycle performance of lithium-ion batteries obtained by assembling the positive electrode materials in Example 1 and Comparative Example 1. As can be seen from Figure 4, the cycle performance of Example 1 is clearly better than that of Comparative Example 1.

[0111] While preferred embodiments of the present invention have been described in detail above, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications to the technical proposals of the present invention are possible, for example, each technical feature can be combined in any other suitable manner, and such simple modifications and combinations should also be considered as part of the disclosure of the present invention and all fall within the scope of protection of the present invention.

Claims

1. Having the composition shown in formula I, Li １＋ａ (Ni ｘ Co ｙ Mn ｚ G ｂ )TO ｃ O ２ (Formula I) Here, 0.02 ≤ a ≤ 0.1, 0.6 ≤ x ≤ 1, 0 < y ≤ 0.5, 0 < z ≤ 0.5, 0 < b ≤ 0.02, 0 < c ≤ 0.02, G is at least one selected from Al, Y, Zr, Ti, Ca, V, Nb, Ta, Co, W, Er, La, Sb, Mg, Sr, Sn, Mn, Mo, Ce, F, B, and P, and T is at least one selected from Al, Sr, Si, Nb, Co, W, Ti, Zr, Ce, Mn, F, B, and P. The (003) characteristic peak around 80 cycles at 45°C, as measured by XRD, 0° ≤ ΔP = P 前 - P 後 ≤ 0.2° satisfies the relationship, where P 前 is the peak position of the (003) characteristic peak before the cycle, and P 後 is the peak position of the (003) characteristic peak after 80 cycles, characterized by a positive electrode material.

2. 0.03 ≤ a ≤ 0.07, 0.6 ≤ x ≤ 1, 0 < y ≤ 0.5, 0 < z ≤ 0.5, 0.005 ≤ b ≤ 0.015, 0.002 ≤ c ≤ 0.015, and / or, G is at least one selected from Al, Ti, Co, Sr, Ce, F, Y, Zr, W, and La, and T is at least one selected from B, Al, Si, W, and F, and / or The positive electrode material according to claim 1, characterized in that 0° ≤ △P ≤ 0.1°.

3. The lattice volume V of the cathode material in the cases of 0% SOC, 50% SOC, and 100% SOC, as measured by XRD, 0% ≤ △V ５０％ = (V ５０ -V ０ ) / V ０ ≤ 10%, and / or 0% ≤ △V １００％ = (V １００ -V ０ ) / V ０ The relationship ≤ 15% is satisfied, Here, V ０ V is the lattice volume of the positive electrode material in the case of 0% SOC. ５０ V is the lattice volume of the positive electrode material in the case of 50% SOC. １００ The positive electrode material according to claim 1 or 2, characterized in that is the lattice volume of the positive electrode material in the case of 50% SOC.

4. The positive electrode material has a specific surface area SSA before and after pressure application, 0%≦△SSA%=(SSA ４ -SSA ０ ) / SSA ０ The relationship ≤ 80% is satisfied, and preferably the relationship 0% ≤ △SSA% ≤ 50%, where SSA ０ This is the specific surface area of ​​the positive electrode material before pressure is applied, and SSA ４ The positive electrode material is characterized in that is the specific surface area of ​​the positive electrode material after being subjected to a pressure of 4.5 tons, as described in any one of claims 1 to 3.

5. The median diameter of the positive electrode material is 2 μm to 20 μm, preferably 3 μm to 18 μm, and / or The positive electrode material is characterized in that the residual alkali content of the positive electrode material is 0 ppm to 10,000 ppm, preferably 1,000 ppm to 8,000 ppm, as described in any one of claims 1 to 4.

6. A method for manufacturing a positive electrode material according to any one of claims 1 to 5, (1) A step of physically mixing a precursor, a lithium source, and an additive containing a selective C1 element to obtain a homogeneous mixture I, (2) In an oxygen-containing atmosphere, perform a first sintering on mixture I, set the constant temperature to T1 and the constant temperature time to t1, and after sintering, crush and sift or sift directly to obtain primary sintered material II. (3) The step of mixing the primary sintered material II with a selective C2 element-containing additive to obtain a homogeneous mixture III, (4) In an oxygen-containing atmosphere, a second sintering is performed on mixture III, the constant temperature is set to T2, the constant temperature time to t2, and after sintering, the mixture is crushed and sieved, or directly sieved, to obtain secondary sintered material IV. (5) A step of mixing the secondary sintered material IV with an additive containing element T to obtain a homogeneous mixture V, (6) The process includes the step of obtaining the positive electrode material by performing a third sintering of the mixture V in an oxygen-containing atmosphere, setting the constant temperature to T3 and the constant temperature time to t3, and then crushing and sieving the mixture after sintering, or by directly sieving the mixture. The precursor is selected from nickel cobalt manganese oxide and / or nickel cobalt manganese hydroxide, and the amounts used for the lithium source, the precursor, the C1 element-containing additive and the C2 element-containing additive are n(Li):[n(Ni)+n(Co)+n(Mn)+n(G)]=1.02 to 1.10:

1. A manufacturing method characterized by adding at least one of an additive containing element C1 and an additive containing element C2.

7. The amounts used for the lithium source, the precursor, the additive containing element C1, and the additive containing element C2 are in the ratio n(Li):[n(Ni)+n(Co)+n(Mn)+n(G)]=1.03-1.07:

1. Preferably, the amounts used of the precursor, the C1-containing additive, and the C2-containing additive in the positive electrode material are such that 0 < n(G): [n(Ni) + n(Co) + n(Mn) + n(G)] ≤ 0.02, and preferably 0.005 ≤ n(G): [n(Ni) + n(Co) + n(Mn) + n(G)] ≤ 0.

015. Preferably, the amount of the secondary sintered material and the additive containing the element T used is such that, in the positive electrode material, 0 < n(T) : [n(Ni) + n(Co) + n(Mn) + n(G)] ≤ 0.02, and preferably, 0.002 ≤ n(T) : [n(Ni) + n(Co) + n(Mn) + n(G)] ≤ 0.015, characterized in that, the manufacturing method according to claim 6.

8. C1 and C2 are each at least one individually selected from Al, Y, Zr, Ti, Ca, V, Nb, Ta, Co, W, Er, La, Sb, Mg, Sr, Sn, Mn, Mo, Ce, F, B, and P, and / or T is at least one selected from Al, Sr, Si, Nb, Co, W, Ti, Zr, Ce, Mn, F, B, and P, preferably at least one selected from B, Al, Si, W, and F. Preferably, C1 is at least one selected from Al, Y, Zr, W, La, Sr, and Ce. Preferably, the manufacturing method according to claim 6 or 7, characterized in that C2 is at least one selected from Al, Ti, Co, Sr, Ce, and F.

9. Constant temperature T １ , constant temperature T ２ , and constant temperature T ３ teeth, 200℃≦T ３ <T ２ <T １ The relationship ≤ 1000℃ is satisfied, Preferably, 200°C ≤ T ３ The relationship ≤ 500°C is satisfied, Preferably, 400°C ≤ T ２ A manufacturing method according to any one of claims 6 to 8, characterized in that it satisfies the relationship ≤ 900°C.

10. A lithium-ion battery characterized by comprising the positive electrode material described in any one of claims 1 to 5.

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