Positive electrode active material, battery, and manufacturing method thereof

Abstract

The present application discloses a positive electrode active material, a battery, and a method for manufacturing the same. The positive electrode active material includes porous secondary particles, and the positive electrode active material satisfies the following characteristic: 4≦BET×TD×(Dv90−Dv10)≦14, where BET represents the value of the specific surface area of ​​the positive electrode active material, and is expressed in units of m 2 / g, and TD represents the tap density of the positive electrode active material, expressed in g / cm 3 where Dv90 is the particle diameter value corresponding to the cumulative volume distribution percentage of the positive electrode active material reaching 90%, and the unit is μm, and Dv10 is the particle diameter value corresponding to the cumulative volume distribution percentage of the positive electrode active material reaching 10%, and the unit is μm. The present application realizes improvement of low-temperature output performance by controlling the particle morphology, size and pore structure of the positive electrode active material, and obtains the effect of increasing the volumetric energy density of the battery by rationally controlling the particle morphology, particle size distribution and tap density of the positive electrode active material.

Description

[Technical Field]

[0001] The present application relates to the field of new energy technology, and specifically to a positive electrode active material, a battery, and a method for manufacturing the same.

[0002] This application claims priority based on a Chinese patent application filed with the China Patent Office on August 23, 2022, bearing application number 202211010331.4 and entitled "Positive electrode active material, battery, and manufacturing method thereof," the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Batteries such as lithium-ion batteries are widely used in various fields due to their advantages, including high specific energy, good power output, low self-discharge, and long cycle life. Currently, the cathode active materials used in electric vehicle batteries are primarily ternary cathode active materials, but their raw materials (e.g., cobalt sulfate and lithium salt) are expensive. To further reduce the cost of electric vehicles, increasing the volumetric energy density of lithium-ion batteries would reduce the space required for the battery module inside the vehicle, which would have a positive impact on the weight and cost of new energy vehicles. Furthermore, the operating environment for electric vehicle batteries is becoming increasingly harsh, and cold climates in particular have a severe impact on battery performance. Therefore, it is necessary to improve the low-temperature performance of batteries, especially their power output at low temperatures. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application provides a cathode active material, a battery, and a manufacturing method thereof that solves the problems of low-temperature output power deficiency and reduced volumetric energy density of batteries manufactured using current cathode active materials. [Means for solving the problem]

[0005] According to a positive electrode active material provided in a first aspect of the present application, the positive electrode active material includes secondary particles, the secondary particles have pores, and the positive electrode active material satisfies the characteristic of 4≦BET×TD×(Dv90−Dv10)≦14, where BET represents the value of the specific surface area of ​​the positive electrode active material, and the unit is m 2 / g, and TD represents the tap density of the positive electrode active material, expressed in g / cm 3 where Dv90 represents the corresponding particle diameter value, expressed in μm, when the cumulative volume distribution percentage of the positive electrode active material reaches 90%, and Dv10 represents the corresponding particle diameter value, expressed in μm, when the cumulative volume distribution percentage of the positive electrode active material reaches 10%.

[0006] Optionally, in another embodiment of the present application, 0.4≦BET≦3.5, 1.2≦TD≦2.6, 4≦Dv90≦18, and 1.5≦Dv10≦6.

[0007] Optionally, in other embodiments of the present application, the maximum pore size of the positive electrode active material is D max nm, and 800≦D max Meets ≦2200.

[0008] Optionally, in another embodiment of the present application, the half-width of the pore size distribution of the positive electrode active material is D HW nm, 150≦D HW Meets ≦450.

[0009] Optionally, in another embodiment of the present application, the porosity P of the positive electrode active material c , 45%≦P c Meet ≦75%.

[0010] Optionally, in another embodiment of the present application, the powder compaction density of the positive electrode active material is P d g / cm 3 and 2.8≦P d Satisfies ≦3.4.

[0011] Optionally, in other embodiments herein, the positive electrode active material has the formula Li x Ni y Co z Me k M pO2, wherein Me is selected from at least one of Mn or Al, and M comprises at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, or Fe, and 0.8≦x≦1.1, 0.5 <y<1、0<z<1、0<k<1、0≦p≦0.1である。

[0012] Optionally, in another embodiment of the present application, the positive electrode active material includes a lithium nickel cobalt manganese oxide, which contains elemental nickel, elemental cobalt, and elemental manganese, and when the sum of the molar amounts of elemental nickel, elemental cobalt, and elemental manganese is 1, the content of elemental nickel is greater than 0.3.

[0013] A method for producing a positive electrode active material provided in a second aspect of the present application includes: mixing either a manganese source or an aluminum source with a nickel source and a cobalt source, adding a precipitating agent and a complexing agent, and reacting to obtain a ternary material precursor; Mixing a ternary material precursor, an M element source, and a lithium source, performing primary sintering, and then cooling and pulverizing to obtain a material containing an M element; and mixing a material containing the M element with a coating element source, followed by secondary sintering to obtain a positive electrode active material.

[0014] Optionally, in other embodiments herein, the positive electrode active material has the formula Li x Ni y Co z Me k M p and a material having O2, wherein Me is selected from at least one of Mn or Al, and M comprises at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, or Fe, and 0.8≦x≦1.1, 0 <y<1、0<z<1、0<k<1、0≦p≦0.1である。

[0015] Optionally, in other embodiments herein, the nickel source comprises at least one of nickel sulfate, nickel acetate, or nickel nitrate.

[0016] Optionally, in other embodiments herein, the cobalt source comprises at least one of cobalt sulfate, cobalt acetate, or cobalt nitrate.

[0017] Optionally, in other embodiments herein, the manganese source comprises at least one of manganese sulfate, manganese acetate, or manganese nitrate.

[0018] Optionally, in other embodiments herein, the aluminum source comprises at least one of aluminum sulfate, aluminum acetate, or aluminum nitrate.

[0019] Optionally, in other embodiments herein, the M element source comprises at least one of zirconium nitrate, tungsten nitrate, aluminum nitrate, titanium nitrate, strontium nitrate, magnesium nitrate, yttrium nitrate, cerium nitrate, indium nitrate, niobium nitrate, lanthanum nitrate, antimony nitrate, vanadium nitrate, zinc nitrate, copper nitrate, chromium nitrate, iron nitrate, tungsten oxide, or zirconium oxide.

[0020] Optionally, in other embodiments herein, the lithium source comprises at least one of lithium hydroxide, lithium carbonate, lithium acetate, or lithium nitrate.

[0021] Optionally, in other embodiments herein, the coating element source comprises one or more of aluminum nitrate, titanium nitrate, cobalt nitrate, tungsten nitrate, yttrium nitrate, silicon oxide, boron oxide, phosphorus pentoxide, or aluminum oxide.

[0022] Optionally, in another embodiment of the present application, the mass percentage of the coating element source in the material containing the M element is 0.3 wt% to 0.7 wt%.

[0023] Optionally, in another embodiment of the present application, the precipitating agent comprises sodium hydroxide solution and the complexing agent comprises aqueous ammonia.

[0024] Optionally, in another embodiment of the present application, the primary sintering temperature is 600 to 1000° C., and the primary sintering time is 3 to 16 hours.

[0025] Optionally, in another embodiment of the present application, the secondary sintering temperature is 400 to 700° C., and the secondary sintering time is 1 to 9 hours.

[0026] A battery provided in a third aspect of the present application includes a positive electrode piece including a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer includes the positive electrode active material described above or a positive electrode active material produced by the production method described above.

[0027] Optionally, in another embodiment of the present application, the positive electrode active material layer comprises: (i) The actual active area of ​​the positive electrode active material layer is A cm 2 and 4×10 4 ≦A≦2×10 5 and (ii) Compressed density PD g / cm of the positive electrode active material layer 3 satisfies 2.4≦PD≦3.5, (iii) Porosity P of the positive electrode active material layer s , 20%≦P s ≦40%; (iv) When the temperature is −20° C. and the state of charge of the battery is 30%, the discharge power per unit volume of the positive electrode active material layer is PW / cm 3 , 8≦P≦30, P=P0×PD / m, P0W represents the discharge power of the battery under the above conditions, PD g / cm 3 represents the compressed density of the positive electrode active material layer, and mg represents the weight of the positive electrode active material layer.

[0028] Alternatively, A and P0 satisfy 0.6≦1000P0 / A≦1.

[0029] A fourth aspect of the present application provides an electrical device comprising the above battery. [Effects of the Invention]

[0030] The positive electrode active material according to the present invention has at least the following technical effects.

[0031] 1) By rationally controlling the particle morphology, particle size distribution, and tap density of the positive electrode active material, the powder compaction density can be effectively increased, thereby improving the compaction ability of the electrode pieces and achieving the effect of increasing the battery volumetric energy density without reducing performance such as output, cycle, storage, and gas generation.

[0032] 2) By controlling the particle morphology, particle size, and pore structure of the positive electrode active material, the specific surface area and porosity of the material can be controlled, the effective contact area between the positive electrode active material and the electrolyte can be increased, and the ion transport, electron transport, and electrolyte diffusion rates can be optimized, improving the output performance of the battery, especially at low temperatures.

[0033] In order to more clearly describe the technical solutions in the embodiments of the present application, the drawings that need to be used in describing the embodiments are briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings based on these drawings without any creative efforts. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is an electron microscope characteristic evaluation test image of the surface morphology of the positive electrode active material obtained in Example 2 of the present application. [Figure 2] 1 is an electron microscope characteristic evaluation test image of the cross-sectional morphology of the positive electrode active material obtained in Example 2 of the present application. [Figure 3] 1 is a flowchart of a method for manufacturing a positive electrode active material provided in an example of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0035] The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application, but obviously, the described embodiments are only a part, not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present application.

[0036] In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits, respectively.

[0037] The present invention provides a cathode active material, a battery, and a method for manufacturing the same. Each of these is described in detail below. Note that the order in which the examples are described below does not limit the preferred order of the examples.

[0038] A first aspect of the present application provides a positive electrode active material, the positive electrode active material including secondary particles, the secondary particles having pores, and an I value of the positive electrode active material satisfying the characteristic of 4≦I=BET×TD×(Dv90−Dv10)≦14, where BET represents the value of the specific surface area of ​​the positive electrode active material, and the unit is m 2 / g, and TD represents the tap density of the positive electrode active material, expressed in g / cm 3 where Dv90 represents the particle size value, in μm, corresponding to the cumulative volume distribution percentage of the positive electrode active material when it reaches 90%, and Dv10 represents the particle size value, in μm, corresponding to the cumulative volume distribution percentage of the positive electrode active material when it reaches 10%. Because low-temperature discharge power performance is primarily affected by the positive electrode pieces of a battery, the present application controls the particle morphology, particle size, particle size distribution, tap density, and pore structure of the positive electrode active material to improve the low-temperature power performance and volumetric energy density of a battery manufactured using this positive electrode active material.

[0039] In some embodiments, I is 4.5≦I≦11.7. For example, I may be 4.5, 4.8, 5.1, 5.6, 6.1, 6.3, 6.9, 7.3, 7.8, 8.1, 8.6, 9.3, 9.7, 10.5, 11.7, or a range consisting of any two of these values. In some embodiments, I is 5.1≦I≦9.7. In some embodiments, I is 5.6≦I≦8.6. When I is within this range, the particle morphology, particle size, particle size distribution, tap density, and pore structure of the positive electrode active material are all in good condition, further improving the low-temperature power performance of the battery and further increasing the volumetric energy density of the battery.

[0040] Currently, from the perspective of materials and battery design, methods for improving the energy density of lithium-ion batteries mainly include increasing the nickel content in the ternary material, increasing the upper voltage limit, and improving the compressibility of the electrode pieces. While the first two solutions can improve the gram capacity of the material, they result in various degrees of degradation of battery performance, such as reduced thermal stability, increased side reactions with the electrolyte, and increased gas generation. The solution of increasing the compressibility of the electrode pieces can increase the volumetric energy density of the battery, but it has problems such as fragile particles, frequent interfacial side reactions, large amounts of gas generation, and shortened long-term life. Therefore, in this application, by controlling the particle morphology, particle size, particle size distribution, tap density, and pore structure of the positive electrode active material, the energy density of the battery and low-temperature power performance can be improved, while reducing gas generation and improving long-term performance.

[0041] In some embodiments of the present application, the BET is 0.4≦BET≦3.5. For example, the BET may be 0.4, 0.8, 1.1, 1.2, 1.4, 1.8, 2.0, 2.3, 2.8, 3.0, 3.5, or a range consisting of any two of these values. In some embodiments of the present application, the BET is 0.4≦BET≦2.7. By controlling the BET of the positive electrode active material within this range, the effective contact area between the positive electrode active material and the electrolyte can be better controlled, side reactions between the positive electrode active material and the electrolyte can be suppressed, and the output performance of the battery can be improved. The BET value can be measured using a specific surface area analyzer (model: Tristar II3020).

[0042] In some embodiments, TD is 1.2≦TD≦2.6. For example, TD may be 1.2, 1.3, 1.4, 1.5, 1.8, 2.1, 2.2, 2.6, or a range consisting of any two of these values. In some embodiments, TD is 1.3≦TD≦2.2. In some embodiments, TD is 1.5≦TD≦2.1. By rationally controlling the tap density of the positive electrode active material, the powder compaction density can be effectively increased, thereby improving the compaction ability of the positive electrode pieces and increasing the battery volumetric energy density. For tap density testing, see GB / T 5162-2021, Measurement of Tap Density of Metal Powders.

[0043] In some embodiments of the present application, 4≦Dv90≦18, and may be, for example, 4.7, 4.8, 4.9, 5.0, 5.2, 5.4, 5.5, 5.8, 10, 15, or a range consisting of any two values ​​thereof. In some embodiments of the present application, 4.9≦Dv90≦15. In some embodiments of the present application, 5.0≦Dv90≦10. 1.5≦Dv10≦6, and may be, for example, 1.5, 1.8, 2.1, 2.2, 2.4, 2.5, 2.6, 2.7, 2.8, 5, or a range consisting of any two values ​​thereof. In some embodiments of the present application, 1.5≦Dv10≦5. In some embodiments of the present application, 1.8≦Dv10≦2.8. By controlling the particle size distribution appropriately, the problem of particle breakage during rolling can be alleviated and the occurrence of interfacial side reactions can be reduced. Dv90, Dv50, and Dv10 are tested using a Malvern laser particle size analyzer.

[0044] In some examples of the present application, 2≦Dv50≦8, where Dv50 represents the particle size value corresponding to when the cumulative volume distribution percentage of the positive electrode active material reaches 50%, and is expressed in μm.

[0045] In some embodiments of the present application, the maximum pore diameter D of the positive electrode active material max nm is 800≦D max≦2200, and may be, for example, 850, 1100, 1200, 1400, 1500, 1700, 1800, 1900, 2000, or a range consisting of any two values ​​thereof. max In some embodiments of the present application, 1100≦D max ≦1900. When the value of I is within the above range and the maximum pore size of the positive electrode active material satisfies the above condition, the pore structure, particle morphology, particle size, particle size distribution, and tap density of the positive electrode active material are controlled within more appropriate ranges, resulting in a battery with high energy density and excellent low-temperature output performance.

[0046] In some embodiments of the present application, the half-width D of the pore size distribution of the positive electrode active material HW nm is 150≦D HW ≦450, and may be, for example, 160, 200, 300, 400, 450, or a range consisting of any two of these values. HW In some embodiments of the present application, 160≦D HW ≦300.

[0047] In some embodiments of the present application, the porosity P c , 45%≦P c ≦75%, for example, 46%, 53%, 54%, 56%, 58%, 62%, 63%, 65%, 66%, 67%, 72%, or a range consisting of any two of these values. c In some embodiments of the present application, 56%≦P c The porosity P of the positive electrode active material is ≦67%. c When the contact area between the positive electrode active material and the electrolyte is within the above range, the contact area between the positive electrode active material and the electrolyte can be controlled to a more optimal range, resulting in better overall battery performance.

[0048] In some embodiments of the present application, the powder compaction density P d g / cm 3 , 2.8≦P d≦3.4, and may be, for example, 2.9, 3.0, 3.1, 3.2, 3.3, or a range consisting of any two of these values. d ≦3.3.

[0049] The pore size distribution and porosity of the positive electrode active material are measured by mercury intrusion porosimetry. d is tested using a compression density meter, and the test process can refer to the national standard GB / T 24533-2019. In this application, by controlling the particle morphology, particle size, and pore structure of the material, the specific surface area and porosity of the material can be controlled, increasing the effective contact area between the positive electrode active material and the electrolyte, optimizing the ion transport, electron transport, and electrolyte diffusion rates, and improving the battery output performance, especially at low temperatures. By controlling the appropriate particle size distribution and compression strength of the positive electrode active material, the problem of particle breakage during rolling can be effectively alleviated, improving the interfacial side reactions of the battery, reducing gas generation, and improving the long-term service life.

[0050] In some embodiments of the present application, the positive electrode active material includes nickel, cobalt, and Me, and when the molar amounts of the nickel, cobalt, and Me are taken as 1, the content of the nickel element is 0.3 or more, and Me is selected from at least one of Mn and Al.

[0051] In some embodiments of the present application, the positive electrode active material includes elemental nickel, elemental cobalt, and elemental Me, and when the molar amounts of the elemental nickel, elemental cobalt, and elemental Me are taken as 1, the content of elemental nickel is 0.5 or more, and Me is selected from at least one of Mn and Al.

[0052] In some embodiments of the present application, the positive electrode active material includes nickel, cobalt, and Me, and the content of nickel is 0.7 or less when the molar amounts of nickel, cobalt, and Me are taken as 1, where Me is at least one of Mn and Al. When the porous positive electrode active material satisfies 4≦BET×TD×(Dv90−Dv10)≦14, controlling the content of nickel within this range can further improve the structural stability of the positive electrode active material, improve ion transport and electron transport in the battery, and more effectively mitigate problems such as reduced thermal stability, intensified side reactions with the electrolyte, and increased gas generation, thereby improving the overall performance of the battery.

[0053] In some embodiments of the present application, the positive electrode active material includes an M element, and the M element includes at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, or Fe.

[0054] In some embodiments of the present application, the positive electrode active material includes an M element, and the M element includes at least one of Y, Nb, In, La, Zr, and Ce, and at least one of W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, and Fe.

[0055] In some embodiments of the present application, the positive electrode active material includes an M element, and the M element includes W and at least one of Y, Nb, In, La, Zr, Ce, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, or Fe.

[0056] Furthermore, the lithium nickel cobalt manganese oxide contains nickel, cobalt, and manganese, and when the sum of the molar amounts of nickel, cobalt, and manganese is taken as 1, the content of nickel is more than 0.3.

[0057] Furthermore, the positive electrode active material has the chemical formula Li x Ni y Co z Me k M pand O2, wherein Me is selected from at least one of Mn or Al, and M comprises at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, or Fe, and 0.8≦x≦1.1, 0 <y<1、0<z<1、0<k<1、0≦p≦0.1である。

[0058] In some embodiments of the present application, the surface of the positive electrode active material particles further comprises a coating material containing at least one coating element selected from Al, Ti, Co, W, Y, Si, B, P, and F. The coating material covers the surface of the positive electrode active material. Specifically, the coating material is applied to the surface of the positive electrode active material by dry coating (high-temperature solid-state method), and the surface of the positive electrode active material is partially or completely covered with a coating layer formed by the coating material. For example, the contact area between the coating layer and the positive electrode active material accounts for 50%, 60%, 70%, 80%, 90%, or 100% of the surface area of ​​the positive electrode active material. The coating material is applied to the surface of the positive electrode active material to improve the structural stability and rate performance of the positive electrode active material.

[0059] In some embodiments of the present application, the positive electrode active material particles have a surface region and a central region adjacent to the surface region, the surface region comprising at least one of Al, Ti, Co, W, Y, Si, B, P, or F, and the central region comprising an element M, where the element M includes Zr and W. The porous positive electrode active material satisfies 4≦I=BET×TD×(Dv90−Dv10)≦14, while the central region of the positive electrode active material comprises the element M and the surface of the positive electrode active material comprises a coating element. This can improve the particle morphology and particle size of the positive electrode active material when used in a positive electrode piece, resulting in better distribution of the positive electrode active material within the positive electrode piece. At the same time, adjusting the composition of the element M and the coating element and selecting better elements for the element M and the coating element can improve the structure of the positive electrode active material and the overall performance of the battery.

[0060] Accordingly, a second aspect of the present application provides a method for producing a positive electrode active material, as shown in FIG. 3, comprising the following steps: S1: Either a manganese source or an aluminum source is mixed with a nickel source and a cobalt source, and a precipitating agent and a complexing agent are added and reacted to obtain a ternary material precursor. S2: The ternary material precursor, the M element source, and the lithium source are mixed, and primary sintering is performed. After cooling and pulverization, a material containing the M element is obtained. S3: A material containing an M element and a coating element source are mixed, and secondary sintering is carried out to obtain a positive electrode active material.

[0061] In this invention, the crystal nucleation rate and growth rate are optimized by changing process parameters such as pH, complexing agent concentration, and synthesis atmosphere during the precursor manufacturing process. The sintering temperature, sintering time, and crushing strength are also controlled. Because the control of the pore structure is highly sensitive to these parameters, the process parameters must be precisely controlled at multiple stages.

[0062] Furthermore, the positive electrode active material has the chemical formula Li x Ni y Co z Me k M p and O2, wherein Me is selected from at least one of Mn or Al, and M comprises at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, or Fe, and 0.8≦x≦1.1, 0 <y<1、0<z<1、0<k<1、0≦p≦0.1である。

[0063] In some embodiments of the present application, the nickel source includes at least one of nickel sulfate, nickel acetate, or nickel nitrate; the cobalt source includes at least one of cobalt sulfate, cobalt acetate, or cobalt nitrate; the manganese source includes at least one of manganese sulfate, manganese acetate, or manganese nitrate; the aluminum source includes at least one of aluminum sulfate, aluminum acetate, or aluminum nitrate; and the M element source is zirconium nitrate, tungsten nitrate, aluminum nitrate, titanium nitrate, strontium nitrate, or magnesium nitrate. the lithium source comprises at least one of lithium hydroxide, lithium carbonate, lithium acetate, or lithium nitrate; and the coating element source comprises at least one of aluminum nitrate, titanium nitrate, cobalt nitrate, tungsten nitrate, yttrium nitrate, silicon oxide, boron oxide, phosphorus pentoxide, or aluminum oxide.

[0064] In some embodiments of the present application, the precipitating agent comprises sodium hydroxide solution and the complexing agent comprises aqueous ammonia.

[0065] Furthermore, the ternary precursor, the M element source, and the lithium source are mixed and sintered, and the sintering temperature may be 600 to 1000°C, 700 to 900°C, or 800 to 880°C, and the temperature may be increased to this temperature at a rate of 5 to 50°C / min, and the sintering time may be 3 to 16 hours, 5 to 15 hours, or 8 to 10 hours.

[0066] Furthermore, the material containing the M element and the coating element source are mixed and sintered, and the sintering temperature may be 400 to 700°C, 450 to 600°C, or 500 to 550°C, and the sintering time may be 1 to 9 hours, 2 to 8 hours, or 3 to 7 hours.

[0067] Specifically, the method for preparing the positive electrode active material includes the following steps: (1) Either a nickel source, a cobalt source, a manganese source, or an aluminum source is weighed according to a certain molar ratio and dissolved in deionized water, respectively. A precursor is synthesized by controlling process conditions such as ammonia water concentration, pH value, stirring speed, reaction time, and reaction temperature, and the pH value can be controlled to, for example, 10 to 13. (2) The precursor obtained in step (1) is uniformly mixed with an M element source and a lithium source, sintered in an oxygen atmosphere, cooled to room temperature, and then pulverized to obtain a material containing the M element. (3) The material containing the M element and the coating element source are uniformly mixed and sintered in an air atmosphere at 400 to 700°C for 1 to 9 hours to obtain a positive electrode active material.

[0068] In addition, a third aspect of the present application provides a battery including a positive electrode piece including a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, wherein the positive electrode active material layer includes the above-described positive electrode active material or a positive electrode active material produced by the above-described production method.

[0069] In some embodiments of the present application, the actual active area of ​​the positive electrode active material layer is A cm 2 and 4×10 4 ≦A≦2×10 5 For example, 4.5 x 10 4 , 6.5×10 4 , 7.6×10 4 , 8×10 4 , 9×10 4 , 1×10 5 , or a range consisting of any two of these values. In some embodiments of the present application, 4 ≦A≦1×10 5 and in some examples of the present application, 7.6×10 4 ≦A≦9×10 4 The actual active area refers to the effective area that can participate in an electrochemical reaction. The actual active area of ​​the positive electrode active material layer is related to the pore structure, pore size distribution, specific surface area, and pressure resistance of the positive electrode active material. The above material parameters and the compressed density of the positive electrode active material layer work together to change the actual active area.

[0070] In some examples of the present application, when the temperature is −20° C. and the state of charge (SOC) of the battery is 30%, the discharge power per unit volume of the positive electrode active material layer is PW / cm 3 , 8≦P≦30, and may be, for example, 8.9, 14, 15, 16, 22, 23, 24, 25, 29, or a range consisting of any two of these values. In some embodiments of the present application, 8.9≦P≦29, and in some embodiments of the present application, 15≦P≦25. The relationship between the low-temperature, low-SOC discharge power P0 of the battery and the actual active area A satisfies 0.6≦1000P0 / A≦1, d, P=P0×PD / m, where P0W represents the discharge power of the battery under the above conditions, and PD g / cm 3 represents the compressed density of the positive electrode active material layer, and mg represents the weight of the positive electrode active material layer.

[0071] In some embodiments of the present application, the compressed density of the positive electrode active material layer is PD g / cm 3 and satisfies 2.4≦PD≦3.5, and may be, for example, 2.6, 2.8, 3.0, 3.1, 3.3, or a range consisting of any two of these values. In some embodiments of the present application, 2.6≦PD s ≦3.1, and the porosity P s , 20%≦P s ≦40%, and may be, for example, 22%, 23%, 25%, 26%, 27%, 28%, 30%, 35%, or a range consisting of any two of these values. s ≦35%, and in some embodiments of the present application, 25%≦P s ≦30%.

[0072] Specifically, the cathode active material described above or the cathode active material prepared by the method described above is uniformly mixed with a conductive agent, a binder, and a solvent, and then the mixture is subjected to processes such as sieving, coating, rolling, slitting, and cutting to produce cathode pieces. By changing the rolling parameters, the corresponding characteristics and parameters of the cathode pieces can also be controlled. The cathode active material layer of the present application can be controlled to satisfy the above characteristics.

[0073] Specifically, the battery comprises a positive electrode piece, a negative electrode piece, a separator, and an electrolyte, the positive electrode piece being the same as the positive electrode piece described above. In a specific implementation, the positive electrode piece, negative electrode piece, separator, and electrolyte are combined to form a lithium-ion battery. The negative electrode material used in the negative electrode piece may be one or more of artificial graphite, natural graphite, mesophase carbon microspheres, amorphous carbon, lithium titanate, or silicon-carbon alloy. The negative electrode material must also have properties such as high compaction density, high mass-specific capacity, and high volume-specific capacity.

[0074] In some embodiments, the electrolyte solution includes an organic solvent, and the organic solvent may include a chain ester and a cyclic ester, with the weight percentage of the chain ester being greater than the weight percentage of the cyclic ester. The cyclic ester may include at least one of ethylene carbonate (EC) or propylene carbonate (PP), and the chain ester may include at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), or diethyl carbonate (DEC). In some embodiments, the solvent of the electrolyte solution includes EC, EMC, and DEC. In some embodiments, the mass ratio of EC, EMC, and DEC is (10-25):(10-25):(51-75). In some embodiments, preparing the electrolyte solution includes dissolving a completely dried lithium salt in an organic solvent in an argon-atmosphere glove box with a water content of less than 10 ppm, and uniformly mixing the solution to obtain the electrolyte solution. Here, the concentration of the lithium salt is 0.8-1.3 mol / L.

[0075] In some embodiments, the lithium salt may be LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), or the like.

[0076] In some embodiments, the preparation of the separator includes selecting a polypropylene film having a thickness of 9 to 18 μm as the separator. There are no particular limitations on the separator, and any separator with a known porous structure having electrochemical stability and mechanical stability may be used.

[0077] A fourth aspect of the present application provides an electrical device comprising the battery described above.

[0078] In some embodiments, the electrical device of the present application may be, but is not limited to, a backup power supply, a motor, an electric vehicle, an electric motorcycle, an electric assist bicycle, a bicycle, a power tool, a large household battery, or the like.

[0079] A specific example will be described below.

[0080] Example 1, This example provides a method for manufacturing a positive electrode active material and a positive electrode piece.

[0081] The preparation of the positive electrode active material includes the following steps: 1) Weigh out nickel sulfate, cobalt sulfate, and manganese sulfate according to the element molar ratio Ni:Co:Mn=0.5:0.2:0.3, dissolve them in deionized water, transport each metal solution to a reactor through a pipeline to form a mixed metal solution, introduce nitrogen as a protective gas, add NaOH aqueous solution as a precipitant and ammonia water as a complexing agent to the mixed metal solution, adjust the ammonia water concentration and pH value of the solution step by step, and react for 10 hours to obtain a precursor. 2) Precursor, lithium carbonate, tungsten oxide and zirconium oxide were mixed uniformly, the lithium ratio was controlled to 1.1:1, and the weight ratios of tungsten oxide and zirconium oxide to the precursor were 0.6 wt% and 0.37 wt%, respectively. 3) The mixed materials are transferred to the sintering process, which consists of two stages, including the first stage sintering at 600°C for 6 hours and the second stage sintering at 880°C for 10 hours. 4) The sintered material is crushed, and the crushed material is uniformly mixed with aluminum oxide, and the weight ratio of aluminum oxide to the crushed material is 0.5 wt%. 5) The mixed material is transferred to the sintering process, where the positive electrode active material is obtained by sintering at a temperature of 450°C for 8 hours. 6) The positive electrode active material, conductive agent, and binder were mixed in a mass ratio of 97:1.5:1.5, and the mixture was uniformly stirred and mixed with a solvent. The mixture was then sieved, coated, rolled, slit, cut, and other processes were carried out to prepare positive electrode pieces. The specific parameters of the positive electrode active material and positive electrode piece were as shown in Tables 1 and 2.

[0082] The manufacturing methods of the cathode active materials and cathode pieces in Examples 2-8, 14-18, and Comparative Examples 1-3 were substantially the same as those in Example 1. The differences were that, in Examples 2-8 and Comparative Examples 1-3, relevant parameters in the cathode active material manufacturing process were changed. In Examples 14-18, additional process parameters, such as the nickel-cobalt-manganese ratio, pH value, ammonia water concentration, and synthesis atmosphere, were changed. This allowed for control of the pore size distribution, porosity, and specific surface area of ​​the cathode active material, resulting in cathode active materials with desired parameter characteristics. Positive electrode pieces manufactured using such cathode active materials also yielded cathode pieces with desired parameter characteristics. See Tables 1 and 2 for specific parameters. Comparative Examples 1-3 illustrate cases where the specific surface area, pore size, and porosity parameters were outside the scope of the present application, making it impossible to achieve the expected actual active area of ​​the cathode active material layer.

[0083] Examples 19 to 22 use the same positive electrode active material, conductive agent, and binder as Example 1. The difference is that Examples 19 to 22 change the rolling parameters in the electrode piece manufacturing process. By controlling the pressed density of the positive electrode pieces, the porosity and actual active area of ​​the positive electrode pieces can be controlled, and positive electrode pieces with predetermined parameter characteristics can be obtained. For specific parameters, see Tables 1 and 2.

[0084] Compared with Example 1, the differences between Examples 9 to 13 are the M element and coating element, but the pore size distribution, specific surface area, and I value of the material are ensured to be within the appropriate range. For specific material parameters and pole piece parameters, please refer to Tables 1 and 2.

[0085] The actual active area A of the positive electrode active material layer was measured in the following manner. 1) Condition the battery to a specified SOC (e.g., 30% SOC). 2) The SOC-adjusted battery is transferred to a glove box and disassembled. A sample is made by cutting a cathode piece using a mold for making a symmetrical battery sample (the size of the cathode piece sample is 46 x 28 mm). An appropriate amount of high-purity anhydrous dimethyl carbonate (DMC) is injected, soaked, and washed. The DMC is replaced every 8 hours, washed three times in a row, and dried for 12 hours, after which a symmetrical battery is made from the cathode piece. 3) Conduct an EIS test on the symmetric battery, read the frequency f corresponding to the maximum radius according to the EIS test curve (Nyquist plot), and calculate the ω max = 2πf according to the angular velocity ω max Calculate. 4) Applying the symmetrical cell EIS, the charge transfer impedance R ct Get a specific value of . 5) Formula A=1 / 20ω max R ct to obtain the real active area A of the electrode.

[0086] [Table 1-1]

[0087] [Table 1-2]

[0088] [Table 1-3]

[0089] [Table 2-1]

[0090] [Table 2-2]

[0091] The lithium-ion batteries of Examples 1-22 and Comparative Examples 1-3 were subjected to low-temperature power tests, high-temperature storage tests, and high-temperature gas generation tests. For the low-temperature power test, the batteries were adjusted to 30% SOC, then left at -20°C to stabilize the battery surface temperature. They were then discharged at a constant power output (P0W) for 10 seconds. If the terminal voltage was between 2.21 and 2.26V, the power test was deemed successful. This P0W was the low-temperature discharge power of the battery. For the high-temperature storage test, the batteries were charged to 4.3V and stored in a thermostatic chamber at 60°C. The remaining capacity was tested every 30 days and then re-stored at full power. The initial capacity (Q0) before storage in the oven was measured, and the remaining capacity (Q) was measured after removal from the thermostatic chamber every 30 days. The battery's storage capacity retention rate was calculated as "Q / Q0 × 100%." The high-temperature gas generation test process involves taking three battery samples, charging them to 4.3V, storing them in a 60°C constant temperature box, and testing the battery volume every 15 days using the drainage method. Fully charging at 1C every 30 days. The initial volume, V0, is tested using the drainage method. After removing the battery from the constant temperature box every 15 days, the battery volume, V, is tested using the drainage method. The high-temperature storage volume expansion rate is calculated as (V / V0-1) x 100%.

[0092] Performance data is shown in Table 3.

[0093] [Table 3]

[0094] Examples 1 to 8 and Comparative Examples 1 to 3 compare the relevant parameters of materials with different pore size distributions, and the pore size D max increases, and the half-width of the pore size distribution D HW As the porosity P of the positive electrode active material increases, c , and through the same electrode and battery manufacturing process, the actual active area A of the positive electrode active material layer increases, improving the low-temperature output performance of the battery.

[0095] Examples 1, 19 to 22, and 14 to 18 compare the relevant parameters of the positive electrode active material layers having different compressed densities, and the compressed densities of the positive electrode active material layers and the porosity P s When the value of I and P changes, the actual active area A of the positive electrode active material layer is affected, and the low-temperature output of the battery is also affected. This means that the appropriate I and P values, which work together to achieve better low-temperature output performance, are required. s and compressed density.

[0096] Examples 1 and 9-10 compare the relevant parameters of materials with different M elements, and show that when the positive electrode active material contains two M elements, especially when it contains W, the overall performance of the battery is better than when it contains only one M element.

[0097] Examples 1 and 11-12 compare the relevant parameters of materials with different coating elements, and the changes and substitutions of the above coating elements do not significantly affect the pore size distribution and porosity of the positive electrode active material, nor do they significantly affect the electrical performance of the battery.

[0098] FIG. 1 shows an electron microscope characteristic evaluation test image of the surface morphology of the positive electrode active material obtained in Example 2 of the present application, and FIG. 2 shows an electron microscope characteristic evaluation test image of the cross-sectional morphology of the positive electrode active material obtained in Example 2 of the present application.

[0099] According to the present application, the actual active area of ​​the positive electrode active material layer is increased without affecting the processing of the slurry and positive electrode pieces, and the effective contact area between the positive electrode active material and the electrolyte is increased, optimizing the ion transport, electron transport, and electrolyte diffusion rates, thereby improving cell output performance, especially at low temperatures. The positive electrode active material produced according to the present application has excellent particle size distribution and compressive strength, effectively alleviating the problem of particle breakage during rolling, improving interfacial side reactions in batteries, reducing gas generation, and improving long-term battery life. The positive electrode active material and positive electrode pieces of the present application have excellent compressibility, allowing for the weight of active material per unit volume to be maintained, thereby ensuring the unit volumetric capacity of the battery.

[0100] The above is a detailed introduction to the cathode active material, battery, and manufacturing method thereof provided in the present application. In this specification, specific examples are used to explain the principles and embodiments of the present application, and the description of the above examples is only used to understand the method and its core idea of ​​the present application. At the same time, those skilled in the art may change specific embodiments and application scope based on the idea of ​​the present application. In summary, the contents of this specification should not be understood as limitations on the present application.

Claims

1. A battery including a positive electrode piece, the positive electrode piece including a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, the positive electrode active material layer comprising: (i) the actual active area of ​​the positive electrode active material layer is A cm 2 , satisfying 4×10 4 ≦A≦2×10 5 , where the actual active area refers to the effective area that can participate in an electrochemical reaction, and is calculated using the formula A=1 / 20ω max R ct and the formula ω max =2πf, where R ct represents the charge transfer impedance, and f represents the frequency corresponding to the maximum radius according to the EIS test curve; (ii) the positive electrode active material layer has a compressed density of PD g / cm 3 , and satisfies 2.4≦PD≦3.5; (iii) the porosity P s of the positive electrode active material layer satisfies at least one of the following characteristics: 20%≦P s ≦40%; the positive electrode active material layer contains a positive electrode active material including secondary particles, The secondary particles have pores, and the positive electrode active material is The following characteristics are satisfied: 4≦BET×TD×(Dv90−Dv10)≦14; and 0.4≦BET≦3.5, 1.2≦TD≦2.6, 4≦Dv90≦18, and 1.5≦Dv10≦6. Here, BET represents the specific surface area of ​​the positive electrode active material, and its unit is m2 / g; TD represents the tap density of the positive electrode active material, and its unit is g / cm3; Dv90 represents the particle diameter value, and its unit is μm, when the cumulative volume distribution percentage of the positive electrode active material reaches 90%; Dv10 represents the particle diameter value, and its unit is μm, when the cumulative volume distribution percentage of the positive electrode active material reaches 10%; The positive electrode active material has a maximum pore size of D max nm, and satisfies 800≦D max ≦2200; The positive electrode active material has a half-width of a pore size distribution of D HW nm, and 150≦D HW ≦450 is satisfied; The positive electrode active material includes a compound having a chemical formula of LixNiyCozMekMpO2, where Me is selected from at least one of Mn or Al, and M includes at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, or Fe, and 0.8≦x≦1.1, 0<y<1, 0<z<1, 0<k<1, and 0≦p≦0.1; the porosity P c of the positive electrode active material satisfies 45%≦P c ≦75%; The battery is characterized in that the powder compressed density of the positive electrode active material is P d g / cm 3 and satisfies 2.8≦P d ≦3.

4.

2. The battery described in Claim 1, characterized in that the positive electrode active material includes lithium nickel cobalt manganese oxide, the lithium nickel cobalt manganese oxide contains nickel element, cobalt element and manganese element, and when the sum of the molar amounts of the nickel element, the cobalt element and the manganese element is 1, the content of the nickel element is more than 0.

3.

3. A method for producing a ternary material precursor, comprising: mixing either a manganese source or an aluminum source with a nickel source and a cobalt source, adding a precipitating agent and a complexing agent, and reacting to obtain the ternary material precursor; mixing the ternary material precursor, the M element source, and the lithium source, performing primary sintering, and then cooling and pulverizing to obtain a material containing the M element; 3. The method for manufacturing a battery according to claim 1, further comprising the step of mixing the material containing the M element with a coating element source and performing secondary sintering to obtain the positive electrode active material.

4. The nickel source includes at least one of nickel sulfate, nickel acetate, or nickel nitrate, the cobalt source includes at least one of cobalt sulfate, cobalt acetate, or cobalt nitrate, the manganese source includes at least one of manganese sulfate, manganese acetate, or manganese nitrate, the aluminum source includes at least one of aluminum sulfate, aluminum acetate, or aluminum nitrate, and the M element source is zirconium nitrate, tungsten nitrate, aluminum nitrate, titanium nitrate, strontium nitrate, magnesium nitrate, yttrium nitrate, cerium nitrate, or tungsten nitrate.

4. The method of claim 3, wherein the lithium source comprises at least one of lithium nitrate, indium nitrate, niobium nitrate, lanthanum nitrate, antimony nitrate, vanadium nitrate, zinc nitrate, copper nitrate, chromium nitrate, iron nitrate, tungsten oxide, or zirconium oxide; the lithium source comprises at least one of lithium hydroxide, lithium carbonate, lithium acetate, or lithium nitrate; and the coating element source comprises one or more of aluminum nitrate, titanium nitrate, cobalt nitrate, tungsten nitrate, yttrium nitrate, silicon oxide, boron oxide, phosphorus pentoxide, or aluminum oxide.

5. A method for manufacturing a battery as described in claim 3, characterized in that the mass percentage of the coating element source in the material containing the M element is 0.3 wt% to 0.7 wt%, the precipitant includes sodium hydroxide solution, and the complexing agent includes ammonia water.

6. A method for manufacturing a battery as described in claim 3, characterized in that the primary sintering temperature is 600 to 1000°C, the primary sintering time is 3 to 16 hours, the secondary sintering temperature is 400 to 700°C, and the secondary sintering time is 1 to 9 hours.

7. An electrical device comprising the battery according to claim 1 or 2.

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