Positive electrode active material, secondary battery, and electrical equipment

Abstract

The present invention discloses a positive electrode active material, a secondary battery, and an electrical device, wherein the positive electrode active material satisfies 300 ≤ P * D / Δθ ≤ 800, where P represents the porosity of the positive electrode active material in %, D represents the crystal plane size of the (110) crystal plane of the positive electrode active material in Å, and Δθ represents the cleavage angle of the diffraction angle at the (110) and (108) crystal planes of the positive electrode active material in °.

Description

[Technical Field]

[0001] This disclosure generally relates to the field of new energy technologies, and more specifically to cathode active materials, as well as to secondary batteries and electrical equipment using these materials. [Background technology]

[0002] With advancements in science and technology, people are demanding more and higher performance from batteries. Batteries are required to have not only high pulse output but also high cycle stability, while conventional batteries fail to meet the needs of modern society in terms of both pulse output and cycle performance. Since battery performance depends to a great extent on electrode materials, developing electrode materials that achieve both high pulse output and long cycle performance is extremely important. [Overview of the project]

[0003] In a first embodiment, this disclosure relates to a positive electrode active material, the positive electrode active material is Satisfying 300 ≤ P*D / Δθ ≤ 800, Here, P represents the porosity of the positive electrode active material, D represents the crystal plane size of the (110) crystal plane of the positive electrode active material, and Δθ represents the cleavage angle of the diffraction angle at the (110) and (108) crystal planes of the positive electrode active material.

[0004] In some embodiments, the porosity P of the positive electrode active material satisfies 30% ≤ P ≤ 65%.

[0005] In some embodiments, the crystal plane size D of the (110) crystal plane of the positive electrode active material satisfies 500 Å ≤ D ≤ 1000 Å.

[0006] In some embodiments, the cleavage angle Δθ of the diffraction angle at the (110) crystal plane and the (108) crystal plane of the positive electrode active material satisfies 0.3° ≤ Δθ ≤ 0.8°.

[0007] In some embodiments, the positive electrode active material has the chemical formula Li x Ni yCo z Mn k M p The compound is represented by O2, where M is at least one of B, Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr and Fe, and 0.8 ≤ x ≤ 1.2, 0 <y<1、0<z<1、0<k<1、0≦p≦0.1とする。

[0008] In some embodiments, the positive electrode active material includes secondary particles, and the secondary particles include primary particles.

[0009] In some embodiments, the particle size ratio of the primary particles to the secondary particles is 1:(10~1000).

[0010] In other embodiments, the disclosure relates to a secondary battery, the secondary battery comprising a negative electrode active material and a positive electrode active material described herein.

[0011] In some embodiments, the secondary battery has a leakage current I of 0A to 0.1A under the conditions of a temperature of 60°C and a voltage of 4.5V to 4.7V.

[0012] In yet another embodiment, the disclosure relates to an electrical device, the electrical device comprising a secondary battery as described in the disclosure.

[0013] In some embodiments, the disclosure specifies the porosity P of the positive electrode active material, the crystal plane size D of the (110) crystal plane of the positive electrode active material, and the cleavage of the diffraction angle at the (110) and (108) crystal planes of the positive electrode active material. Δθ This satisfies 300 ≤ P*D / Δθ ≤ 1000, and as a result, lithium-ion batteries made using this positive electrode active material have high pulse output and significantly improved cycle performance. [Brief explanation of the drawing]

[0014] To more clearly illustrate the technical solutions of this disclosure, the drawings necessary for describing the embodiments are briefly described below. As will be apparent, the drawings in the following description are of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these without expending any creative work. [Figure 1] This is an electron microscope image of the positive electrode active material prepared in Example 1 of this disclosure. [Modes for carrying out the invention]

[0015] The technical solutions in the embodiments are described below clearly and completely. Clearly, the embodiments described below are only a selection of the embodiments of this disclosure, not all of them. All other embodiments that a person skilled in the art could obtain without creative work based on the embodiments of this disclosure are all within the scope of this disclosure.

[0016] Where used herein and in the appended claims, the terms “includes” and “inclusive” indicate the presence of a described feature, whole, step, operation, element and / or component, but should be understood not to exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or sets thereof.

[0017] Furthermore, it should be understood that the terms used in this disclosure are used solely for the purpose of describing specific embodiments and are not intended to limit this disclosure. As used in this disclosure and the attached claims, unless the context clearly indicates otherwise, the singular forms "one," "one," and "the" are intended to include the plural form.

[0018] One embodiment of the present disclosure provides a positive electrode active material, the positive electrode active material is Satisfying 300 ≤ P*D / Δθ ≤ 800, Here, P represents the porosity of the positive electrode active material, with the unit of %, D represents the crystal plane size of the (110) crystal plane of the positive electrode active material, with the unit of Å, and Δθ represents the splitting degree of the diffraction angle between the (110) crystal plane and the (108) crystal plane of the positive electrode active material, with the unit of °.

[0019] In some embodiments, P*D / Δθ can be any value among 300, 320, 350, 380, 390, 400, 420, 450, 480, 500, 520, 540, 550, 570, 600, 650, 670, 690, 700, 720, 750, 780, 800, or a range composed of any two of these numerical values.

[0020] In some embodiments, the positive electrode active material satisfies 300 ≤ P*D / Δθ ≤ 700. In some embodiments, the positive electrode active material satisfies 325 ≤ P*D / Δθ ≤ 600. By controlling the parameters of each step in the manufacturing process of the positive electrode active material, the porosity, crystal plane size, and crystallinity of the active material can be appropriately adjusted, and the value of P*D / Δθ can be controlled within the range of the present disclosure. Thereby, it is advantageous for improving the structural stability of the positive electrode active material and the wettability of the electrolyte, and thus the manufactured battery has excellent low-temperature output characteristics and good long-term life.

[0021] In some embodiments, the porosity P of the positive electrode active material satisfies 30% ≤ P ≤ 65%. In some embodiments, P can be any value among 30%, 33%, 35%, 38%, 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, 60%, 65%, or a range composed of any two of these numerical values. The porosity of the positive electrode active material within the range of the present disclosure ensures that the electrolyte is sufficiently wetted, which is advantageous for the exertion of capacity. At the same time, it ensures the structural stability during the charge-discharge cycle process, suppresses the occurrence of side reactions, and can improve the battery life.

[0022] In some embodiments, 32% ≤ P ≤ 59%.

[0023] In some embodiments, 34% ≤ P ≤ 57%.

[0024] In some embodiments, the crystal plane size D of the (110) crystal plane of the positive electrode active material satisfies 500 Å ≤ D ≤ 1000 Å. In some embodiments, D can be any value from 500 Å, 520 Å, 540 Å, 550 Å, 570 Å, 600 Å, 650 Å, 670 Å, 690 Å, 700 Å, 720 Å, 750 Å, 780 Å, 800 Å, 830 Å, 850 Å, 890 Å, 900 Å, 950 Å, 1000 Å, or a range consisting of any two of these values. The crystal plane size D of the (110) crystal plane of the positive electrode active material within the scope of this disclosure is advantageous for rapid lithium ion transport and for improving the rate characteristics and power characteristics of the battery.

[0025] In some embodiments, 510 Å ≤ D ≤ 840 Å.

[0026] In some embodiments, 500 Å ≤ D ≤ 700 Å. When the crystal plane size D of the (110) crystal plane of the positive electrode active material is within the above range, the overall performance of the battery can be improved.

[0027] In some embodiments, the cleavage angle Δθ of the diffraction angle at the (110) crystal plane and the (108) crystal plane of the positive electrode active material satisfies 0.3° ≤ Δθ ≤ 0.8°. In some embodiments, Δθ can be any value from 0.3°, 0.35°, 0.37°, 0.4°, 0.43°, 0.45°, 0.47°, 0.5°, 0.52°, 0.55°, 0.57°, 0.6°, 0.63°, 0.65°, 0.68°, 0.7°, 0.73°, 0.75°, 0.77°, 0.8°, or a range consisting of any two of these values. If the cleavage angle Δθ of the diffraction angle at the (110) crystal plane and the (108) crystal plane is within the range of this disclosure, the layered structure of the positive electrode active material has better integrity and better crystal performance, thus providing the battery with better overall performance.

[0028] In some embodiments, 0.36° ≤ Δθ ≤ 0.73°.

[0029] In some embodiments, 0.38° ≤ Δθ ≤ 0.71°.

[0030] In some embodiments, 0.41° ≤ Δθ ≤ 0.69°. When Δθ is within the above range, the integrated performance of the secondary battery can be further improved.

[0031] In some embodiments, the cathode active material has a chemical formula of Li x Ni y Co z Mn k M p and contains a compound represented by O2, where M contains at least one of B, Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, and Fe, and 0.8 ≤ x ≤ 1.2, 0 < y < 1, 0 < z < 1, 0 < k < 1, 0 ≤ p ≤ 0.1.

[0032] In some embodiments, 0.3 < y < 0.95.

[0033] In some embodiments, 0.45 < y < 0.90.

[0034] In some embodiments, 0.45 < y < 0.85.

[0035] In some embodiments, 0.45 < y < 0.75.

[0036] In some embodiments, M contains B and further contains at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, and Fe.

[0037] In some embodiments, M contains B and W and contains at least one of Y, Nb, In, La, Zr, Ce, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, and Fe.

[0038] In some embodiments, the positive electrode active material includes secondary particles, and the secondary particles include primary particles. In some embodiments, the particle size ratio of primary particles to secondary particles is 1:(10~1000).

[0039] In some embodiments, the particle size ratio of primary particles to secondary particles is 1:(100~1000).

[0040] In some embodiments, the particle size ratio of primary to secondary particles can be any of the following values: 1:100, 1:200, 1:400, 1:600, 1:800, 1:1000, or a range consisting of any two of these values. When the particle size ratio of primary to secondary particles is within the above range, it is advantageous for shortening the lithium ion transport path and improving the battery's output characteristics and cycle life.

[0041] In some embodiments, the surface of the positive electrode active material contains Li2CO3 and / or LiOH. Based on the mass of the positive electrode active material, the Li2CO3 content is 500 ppm to 1000 ppm, and the LiOH content is 1000 ppm to 3000 ppm. Residual lithium decomposes during the charge-discharge process, generating gas and affecting long-term performance and safety performance. However, because the amount of residual lithium on the surface of the positive electrode active material proposed in the embodiments of this disclosure is low, excellent performance can be imparted to the lithium-ion battery.

[0042] In some embodiments, the present disclosure provides a method for producing a positive electrode active material, and the production method is as follows: The process involves weighing nickel sulfate, cobalt sulfate, and manganese sulfate according to a fixed Ni:Co:Mn elemental molar ratio, dissolving each in deionized water, supplying each metal solution to a reaction vessel via piping to prepare a mixed metal solution, simultaneously introducing nitrogen gas as a protective gas, adding an aqueous NaOH solution as a precipitating agent and aqueous ammonia as a complexing agent to the mixed metal solution, and then gradually adjusting the ammonia concentration and pH value of the solution, and carrying out the reaction for 10 to 48 hours to obtain a precursor.

[0043] A positive electrode active material precursor, lithium hydroxide, and doping material are mixed to obtain a first mixed raw material. Then, the first mixed raw material is subjected to a first calcination in an oxygen atmosphere to obtain an intermediate product, with the oxygen concentration in the oxygen atmosphere being 30% to 60%.

[0044] In some embodiments, the molar ratio a / b of the positive electrode active material precursor to lithium hydroxide is 1.03 to 1.09. Here, a represents the molar content of lithium in the lithium hydroxide, and b represents the total molar content of Ni, Co, and Mn in the positive electrode active material precursor. In some embodiments, a / b is 1.03.

[0045] In some embodiments, the metal oxide includes at least one of CoO2, MnO2, Al2O3, B2O3, ZrO2, SnO2, NbO, TiO2, V2O3, WO2, and MoO3.

[0046] In some embodiments, the mixing of the positive electrode active material precursor, lithium hydroxide, and metal oxide can be performed in a high-speed mixer, and the mixing time can be set to 0.5 to 2 hours. In some embodiments, the mixing time is 1 to 2 hours.

[0047] In some embodiments, the first firing can be performed in an atmospheric firing furnace, where the firing atmosphere is an oxygen atmosphere with an oxygen concentration of 30% to 60%. In some embodiments, the oxygen concentration is 40% to 50%. In some embodiments, the parameters for the first firing are a firing temperature of 650°C to 950°C and a firing time of 4 to 24 hours. In some embodiments, the firing temperature can be 700°C to 900°C and the firing time can be 8 to 12 hours.

[0048] In some embodiments, the intermediate product and a metal oxide are mixed to obtain a second mixed raw material, and then the second mixed raw material is subjected to a second calcination to obtain the positive electrode active material.

[0049] In some embodiments, the mixing of the intermediate product and the metal oxide can be performed in a high-speed mixer, and the mixing time can be set to 0.5 to 2 hours. In some embodiments, the mixing time is 1 to 2 hours.

[0050] In some embodiments, the second firing can be performed in an atmospheric firing furnace, where the firing atmosphere is air. The parameters for the second firing are a firing temperature of 200°C to 500°C and a firing time of 6 to 14 hours. In some embodiments, the firing temperature can be 300°C to 500°C and the firing time can be 7 to 12 hours.

[0051] In some embodiments, the crystal plane size of the (110) crystal plane of the positive electrode active material, the cleavage angle of the diffraction angles of the (110) and (108) crystal planes of the positive electrode active material, and the porosity of the positive electrode active material are influenced by the manufacturing process described above. By adjusting and controlling the ammonia concentration and pH value, the structure and crystal plane growth rate of the precursor can be adjusted to obtain precursors having different active crystal planes and sparse densities. Then, by controlling the lithium content ratio, temperature, time, etc., during calcination, the positive electrode active material described in this disclosure can be obtained. The manufacturing process of the positive electrode active material described in this disclosure is advantageous for obtaining crystals with long-range order and high uniformity, and the positive electrode active material maintains structural integrity during long-term charge-discharge processes, contributing to improved battery cycle performance.

[0052] In another embodiment, the Disclosure provides a secondary battery comprising a negative electrode active material and a positive electrode active material described herein.

[0053] In some embodiments, the secondary battery has a leakage current I of 0A to 0.1A under conditions of a temperature of 60°C and a voltage of 4.5V to 4.7V. The secondary battery of this disclosure has a low leakage current and exhibits excellent cycle performance.

[0054] In some embodiments, the secondary battery is charged with a constant current to a predetermined set voltage, and then the secondary battery is charged with a constant voltage at the set voltage for a predetermined time. In some embodiments, the set voltage is 4.5V to 4.7V, and the predetermined time is 15 time It takes approximately 25 hours.

[0055] In some embodiments, the quality of the cycle performance can be determined from the magnitude of the leakage current of the secondary battery. In some embodiments, multiple levels of leakage current ranges can be set, and the quality of the cycle performance of the secondary battery can be determined based on the leakage current in each range.

[0056] In yet another embodiment, the present disclosure provides an electrical device comprising a secondary battery described herein.

[0057] Examples Example 1 Step 1: The cathode active material precursor M(OH)2, LiOH, and ZrO2 are placed in a high-speed mixer in a molar ratio of 1:1.09:0.002 and mixed for 1 hour to obtain the first mixed raw material. The first mixed raw material is placed in an atmospheric calcination furnace and calcined for the first time to obtain an intermediate product. The parameters for the first calcination are a calcination temperature of 880°C, a calcination time of 8 hours, and a calcination atmosphere of 50% oxygen. Here, the chemical formula of the positive electrode active material precursor is [Ni 0.5 Co 0.2 Mn 0.3 The positive electrode active material precursor is manufactured by coprecipitation and has a loosely porous structure. The molar ratio a / b of lithium hydroxide to positive electrode active material precursor is 1.09, where a represents the molar content of lithium in lithium hydroxide and b represents the total molar content of Ni, Co, and Mn in the positive electrode active material precursor. The molar content of nickel in lithium nickel cobalt manganese oxide accounts for 50% of the total molar content of nickel, cobalt, and manganese. Step 2: The intermediate product obtained in Step 1 and B2O3 are placed in a high-speed mixer in a molar ratio of 1:0.001 and mixed for 1 hour to obtain the second mixed raw material. The second mixed raw material is placed in an atmospheric firing furnace and fired a second time to obtain the positive electrode active material. The parameters for the second firing are a firing temperature of 300°C, a firing time of 8 hours, and a firing atmosphere of air.

[0058] Manufacturing of lithium-ion batteries: (1) Manufacturing of positive electrode plate: The positive electrode active material, acetylene black, and polyvinylidene fluoride are dispersed in N-methylpyrrolidone (NMP) in a mass ratio of 92:6:2. The resulting slurry is coated onto 12 μm aluminum foil, dried in an oven at 120°C, and then subjected to cold pressing and slitting to obtain a positive electrode plate. (2) Preparation of electrolyte: Mix ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:20:60 to prepare a mixture. In an argon atmosphere glove box with a moisture content of <10 ppm, thoroughly dry 1 mol / L LiPF6 mixed liquid Dissolve it in and mix it uniformly to obtain an electrolyte solution. (3) Manufacturing of negative electrode plate: Graphite, sodium carboxymethylcellulose, styrene-butadiene rubber, and acetylene black are mixed in a mass ratio of 95:1:2:2, deionized water is added, and the mixture is stirred in a vacuum mixer to obtain a negative electrode slurry. The negative electrode slurry is uniformly applied to a copper foil with a thickness of 8 μm, dried in an oven at 120°C, and then cold-pressed and slit to obtain a negative electrode plate. (4) Manufacturing of lithium-ion batteries: A positive electrode plate, a separator, and a negative electrode plate are stacked in order, and the separator is placed between the positive and negative electrode plates to provide isolation. After winding, a rectangular jelly roll structure is created and then sealed in an aluminum laminate film. Next, the moisture is removed by heating and drying at 80°C, the electrolyte is injected and sealed, and a lithium-ion battery is obtained through processes such as standing, hot and cold pressurization, chemical conversion, jig fixing, and capacity separation.

[0059] The manufacturing methods for other examples and comparative examples refer to Example 1, but the differences are as shown in Table 1.

[0060] [Table 1]

[0061] Measurement method explanation 1. Cleavage of the (110) and (108) crystal planes. A fixed mass of positive electrode active material powder is placed in an X-ray powder diffractometer, and the 2θ angles corresponding to the diffraction peaks of the (110) crystal plane and the 2θ angles corresponding to the diffraction peaks of the (108) crystal plane are obtained by X-ray diffraction analysis, thereby obtaining the cleavage angles of the (110) and (108) crystal planes. 2. Crystal plane size of the (110) crystal plane A certain mass of positive electrode active material powder is placed in an X-ray powder diffractometer, and the crystal plane size of the (110) crystal plane is obtained by X-ray diffraction analysis. 3, porosity The porosity of the positive electrode active material can be measured by the mercury intrusion method; refer to GB / T21650.1-2008 "Measurement of pore size distribution and porosity of solid materials by mercury intrusion and gas adsorption methods". 4. Output Charge the battery to 100% with a constant current of 1C. Charging status ( SOC ) The battery is charged at a constant voltage until it reaches a certain level, left to stand for 10 minutes, discharged at a constant current of 1C for 30 minutes to adjust to 50% SOC, left to stand for 180 minutes in a -20°C environment, discharged at 5C for 30 seconds, the voltage values ​​before and after discharge are recorded, and the discharge output is calculated. 5. Method for measuring leakage current Lithium-ion batteries are fabricated using the positive electrode active materials of the respective examples and comparative examples. As a method for measuring leakage current, the lithium-ion battery is charged to 4.7V with a constant current, then the lithium-ion battery is charged at a constant voltage of 4.7V for 20 hours, and the leakage current of the lithium-ion during the 20 hours of constant voltage charging is obtained. 6. Cycle performance measurement First, the battery voltage is calibrated to determine the voltages corresponding to the battery's 25% SOC and 85% SOC. Then, cycle charging and discharging is performed in a constant temperature bath at 25°C, using a constant current of 5C, and the battery's cycle capacity and number of cycles are recorded. This allows for obtaining the capacity retention rate after 5000 cycles.

[0062] The measurement results for the examples and comparative examples are shown in Table 2 below.

[0063] [Table 2]

[0064] Analysis of experimental results: Comparing Examples 1-16 with Comparative Examples 1-2, it can be confirmed that when 300 ≤ P*D / Δθ ≤ 800 is within the scope of this disclosure, both the battery output and cycle performance are improved, and the battery leakage current is reduced.

[0065] Examples 1-7 and Comparative Examples 1-2 compared the effects of different sintering temperature and time process parameters on the material. When the sintering temperature was too high and the time was too long, the crystallinity and particle separation of the material improved, but the (110) crystal planes decreased and the porosity decreased, resulting in a deterioration of output performance. On the other hand, when the sintering temperature was too low, the material synthesis failed, resulting in poor performance.

[0066] In the above embodiments, each embodiment has its own emphasis. For parts not explained in detail in one embodiment, you can refer to the relevant explanations in other embodiments.

[0067] In this specification, any reference to terms such as “one example,” “some examples,” “exemplary,” “specific examples,” or “partial examples” means that the specific features, structures, materials, or properties described in such example or example are included in at least one example or example of this disclosure. In this specification, a general description of the above terms should not necessarily be construed as applying to the same example or example. Furthermore, the specific features, structures, materials, or properties described may be combined in an appropriate manner in any one or more examples or examples. Moreover, those skilled in the art may combine and integrate different examples or examples described herein.

[0068] Clearly, those skilled in the art can make various modifications and variations of this disclosure without departing from the spirit and scope of this disclosure. Thus, if such modifications and variations of this disclosure fall within the scope of the claims of this disclosure and the equivalent art, this disclosure is intended to encompass such modifications and variations as well.

[0069] The above describes specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any equivalent modifications or substitutions that a person skilled in the art could easily conceive of within the scope of the art disclosed herein are all included within the scope of protection of the present disclosure. Accordingly, the scope of protection of the present disclosure shall be equivalent to the scope of protection of the claims. [Cross-reference of related applications]

[0070] This disclosure claims priority to the patent application filed with the China National Patent Office on 18 May 2023, application number 202310567615.1, with the title of the invention "Positive electrode active material, and secondary battery and electrical equipment thereof," all of which are incorporated herein by reference.

Claims

1. It is a positive electrode active material, Satisfying 300 ≤ P * D / Δθ ≤ 800, A positive electrode active material in which P represents the porosity of the positive electrode active material in %, unit: %, D represents the crystal plane size of the (110) crystal plane of the positive electrode active material in Å, unit: Δθ represents the cleavage between the diffraction angle at the (110) crystal plane and the diffraction angle at the (108) crystal plane of the positive electrode active material in °.

2. The positive electrode active material according to claim 1, wherein the porosity P of the positive electrode active material satisfies 30% ≤ P ≤ 65%.

3. The positive electrode active material according to claim 1 or 2, wherein the crystal plane size D of the (110) crystal plane of the positive electrode active material satisfies 500 Å ≤ D ≤ 1000 Å.

4. The positive electrode active material according to any one of claims 1 to 3, wherein the cleavage angle Δθ between the diffraction angle on the (110) crystal plane and the diffraction angle on the (108) crystal plane of the positive electrode active material satisfies 0.3° ≤ Δθ ≤ 0.8°.

5. The positive electrode active material has the chemical formula Li ｘ Ni ｙ Co ｚ Mn ｋ M ｐ O ２ A positive electrode active material according to any one of claims 1 to 4, comprising a compound represented by , wherein M comprises at least one of B, Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr, and Fe, and the following conditions are met: 0.8 ≤ x ≤ 1.2, 0 < y < 1, 0 < z < 1, 0 < k < 1, 0 ≤ p ≤ 0.

1.

6. The positive electrode active material according to any one of claims 1 to 5, wherein the positive electrode active material includes secondary particles, and the secondary particles include primary particles.

7. The positive electrode active material according to claim 6, wherein the particle size ratio of the primary particles to the secondary particles is 1:(10 to 1000).

8. A secondary battery comprising a negative electrode active material and a positive electrode active material according to any one of claims 1 to 7.

9. The secondary battery according to claim 8, wherein the leakage current I is 0A to 0.1A under the conditions of a temperature of 60°C and a voltage of 4.5V to 4.7V.

10. An electrical device comprising a secondary battery according to claim 8 or 9.

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