Positive electrode active material and preparation method thereof, battery and electric device

Abstract

The invention discloses a positive electrode active material and a preparation method thereof, a battery and an electric device. The positive electrode active material includes: an inner core including lithium manganese oxide; the carbon coating layer at least covers part of the surface of the inner core, the carbon coating layer comprises a first metal element M, and the dissociation energy of an M-O bond is greater than the dissociation energy of an Mn-O bond. Therefore, the electronic conductivity of the positive electrode active material can be improved through the arrangement of the carbon coating layer, and the ionic conductivity of the positive electrode active material can be improved through the first metal element M in the carbon coating layer.

Description

[0001] This application is a divisional application of the application for patent with application number 202310641003.2, application date of May 31, 2023, and title of "Positive Electrode Active Material and Preparation Method Thereof, Battery, and Electric Device". TECHNICAL FIELD

[0002] The present application relates to the field of batteries, in particular, to a positive electrode active material and a preparation method thereof, a battery, and an electric device. BACKGROUND

[0003] With the development of lithium ion battery technology, lithium ion batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations due to their high energy density, long cycle life, and green environmental protection. They are also widely used in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the advantages of low cost, safety and reliability, high working voltage, and fast lithium ion transmission channel, lithium manganese oxide is considered to be a very promising positive electrode active material for power lithium ion batteries. However, the poor cycle performance of lithium manganese oxide makes it still have many problems to be solved in the application level.

[0004] The above statements are only used to provide background technical information related to the present application, and do not necessarily constitute the prior art. SUMMARY

[0005] In a first aspect of the present application, a positive electrode active material is provided, comprising: an inner core, the inner core comprising lithium manganese oxide; a carbon coating layer, the carbon coating layer covering at least part of the surface of the inner core, the carbon coating layer comprising a first metal element M, the dissociation energy of the M-O bond being greater than the dissociation energy of the Mn-O bond. Thus, by providing a carbon coating layer, the electronic conductivity of the positive electrode active material can be improved, and by using the first metal element M in the carbon coating layer, the ionic conductivity of the positive electrode active material can be improved.

[0006] According to an embodiment of the present application, the inner core further comprises the first metal element M, and the first metal element M is located on the side surface of the inner core close to the carbon coating layer. Thus, the crystal structure stability of the inner core can be further improved.

[0007] According to an embodiment of the present application, the first metal element M comprises at least one of Ti, Mg, Al, Cr, Ni, and Co; preferably, the first metal element M comprises Al. Thus, the crystal structure stability of the inner core can be improved.

[0008] According to an embodiment of the present application, the carbon coating layer comprises an oxide of the first metal element M. Thus, it is helpful to form a solid solution that can improve the crystal structure stability of the inner core.

[0009] According to the embodiment of the present application, the lithium manganese oxide includes at least one of a lithium-rich manganese-based solid solution, a nickel-cobalt-manganese ternary material, a lithium manganese phosphate, and a lithium manganate. Thus, the manufacturing cost of the positive electrode active material can be reduced.

[0010] According to the embodiment of the present application, the lithium manganese oxide satisfies at least one of the following conditions: the lithium-rich manganese-based solid solution satisfies the general formula: xLi a [Li 1 / 3 Mn 2 / 3 ]O b ·(1-x)Li c M1O d , wherein 0 e Ni f Co g Mn h M2 i O j , wherein 0.9 k Mn 1-m M3 m PO n , wherein 0.9 p Mn 2-q M4 q O s , wherein 0.9 Thus, the manufacturing cost of the positive electrode active material can be further reduced, and the gram capacity of the positive electrode active material can be improved.

[0011] According to the embodiment of the present application, the particle size of the core is 7 μm-15 μm, and optionally, the particle size of the core is 9 μm-12 μm. Thus, the dispersibility of the positive electrode active material in the positive electrode slurry can be improved.

[0012] According to the embodiment of the present application, the thickness of the carbon coating layer is d1, the particle size of the core is d2, and d1:d2 is 0.01-0.1. In this way, the positive electrode active material can have both high electronic conductivity and high gram capacity.

[0013] According to the embodiment of the present application, the mass fraction of the carbon coating layer in the positive electrode active material is 1%-3%. In this way, the electronic conductivity and gram capacity of the positive electrode active material can be improved.

[0014] According to the embodiment of the present application, the number of moles of the first metal element M in the carbon coating layer is m1, and the number of moles of manganese in the core is m2, and m1:m2 is 0.01%-0.5%. In this way, the crystal structure stability of the core can be improved.

[0015] In the second aspect of the present application, a method for preparing the positive electrode active material is provided, which comprises: mixing the core with the metal organic framework material to obtain a precursor, and heating the precursor to obtain the positive electrode active material. In this way, the positive electrode active material can be prepared by a relatively simple method, and the method has all the features and advantages of the positive electrode active material, which will not be repeated here.

[0016] According to the embodiment of the present application, the mass fraction of the metal organic framework material in the precursor is 1%-5%. In this way, the content of the carbon coating layer in the positive electrode active material can be controlled.

[0017] According to the embodiment of the present application, the metal organic framework material satisfies at least one of the following conditions: the metal center of the metal organic framework material comprises at least one of Ti, Mg, Al, Cr, Ni, and Co; and the organic ligand of the metal organic framework material comprises at least one of terephthalic acid, 1,2-cyclohexane dicarboxylic acid, 1,2,4-benzene tricarboxylic acid, 1,2-di(4-pyridyl)ethylene, 1,3,5-tris(4-carboxyphenyl)benzene, 2,2'-bipyridine, 2,5-dihydroxyterephthalic acid, and 2,5-dihydroxyterephthalic acid ethyl ester. In this way, the carbon coating layer with one or more first metal elements can be obtained.

[0018] According to an embodiment of the present application, the heating treatment comprises a temperature rising process, a temperature maintaining process and a temperature falling process, and the heating treatment satisfies at least one of the following conditions: a temperature rising rate of the temperature rising process is 2-8 ℃ / min, and a highest temperature of the temperature rising process is 450-900 ℃; a temperature maintaining time of the temperature maintaining process is 10-15 h, and a temperature of the temperature maintaining process is the highest temperature of the temperature rising process; a temperature falling rate of the temperature falling process is 4-10 ℃ / min, and a lowest temperature of the temperature falling process is less than or equal to 200 ℃. Thus, the positive electrode active material with a better crystal plane orientation can be obtained.

[0019] In a third aspect of the present application, a battery is provided, which comprises a positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer at least on one side of the positive electrode current collector, wherein the positive electrode active material layer comprises the aforementioned positive electrode active material, and / or the positive electrode active material prepared by the aforementioned method. Thus, the battery has all the features and advantages of the aforementioned positive electrode active material, which will not be repeated here.

[0020] In a fourth aspect of the present application, an electric device is provided, which comprises the aforementioned battery. Thus, the electric device has all the features and advantages of the aforementioned battery, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein: Figure 1 A structural schematic diagram of a positive electrode active material according to an embodiment of the present application is shown; Figure 2 A structural schematic diagram of a positive electrode active material according to another embodiment of the present application is shown; Figure 3 A schematic diagram of a battery according to an embodiment of the present application is shown; Figure 4 is Figure 3 An exploded view of a battery according to an embodiment of the present application is shown; Figure 5 A schematic diagram of a battery module according to an embodiment of the present application is shown; Figure 6 A schematic diagram of a battery pack according to an embodiment of the present application is shown; Figure 7 is Figure 6 An exploded view of a battery pack according to an embodiment of the present application is shown; Figure 8 A schematic diagram of an electric device using the battery as a power source according to an embodiment of the present application is shown.

[0022] Reference Signs List: 1: battery pack, 2: upper case, 3: lower case, 4: battery module, 5: battery, 10: core, 20: carbon coating layer, 21: first metal element M, 22: oxide of the first metal element M, 51: shell, 52: electrode assembly, 53: top cover assembly. DETAILED DESCRIPTION

[0023] Embodiments of the present application are described below in detail with reference to examples illustrated in the accompanying drawings, in which like or similar elements or elements having the same or similar functions are denoted by the same or similar reference numerals throughout the drawings. The embodiments described below by reference to the drawings are exemplary and are for the purpose of explaining the present application only, and are not to be understood as limiting the present application.

[0024] In the description of the present application, it is to be understood that the orientation or positional relationship indicated by the terms "thickness" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0025] In the description of the present application, "A and / or B" can include any one of the case of A alone, the case of B alone, and the case of A and B, where A and B are used only for example, and can be any technical feature connected by "and / or" in the present application.

[0026] In the description of the present application, the meaning of "a plurality of" is two or more.

[0027] Unless otherwise specified, all technical terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. All patents and publications referred to in the present application are incorporated by reference in their entirety. The terms "comprising" or "including" are open-ended expressions, i.e., include the contents indicated in the present application, but do not exclude other aspects.

[0028] In the description of the present application, all numbers disclosed herein are approximate. The numerical parameters set forth in the specification and attached claims are approximations that can vary depending on the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. At the very least, each numerical limitation or numerical value set forth in the detailed description and claims is intended to indicate at least one

[0029] The poor cycle performance of lithium manganese oxide is attributed to manganese dissolution and irreversible phase transition occurring in the lithium manganese oxide during charging and discharging. Taking lithium manganate as an example, in the spinel structure of lithium manganate, the average valence of manganese is +3.5, a part of Mn exists in the form of +3 valence, and Mn 3+very unstable and easy to disproportionation to form Mn 4+ (solid) and Mn 2+ (solution), the generated Mn 2+ dissolved in the liquid electrolyte, and then deposited on the negative electrode plate after being reduced on the surface of the negative electrode plate, resulting in an increase in the impedance of the electrode plate, and also causing the structure of the skeleton Mn2O4 to be destroyed, with poor structural stability during the charging and discharging process, resulting in a decrease in the cycle performance.

[0030] At the same time, when the electrolyte contains moisture, the water reacts with the lithium salt to generate HF, which reacts with lithium manganate to cause the Mn 2+ dissolved in the electrolyte and the generation of water, which further aggravates the side reaction, thus causing a vicious cycle. In addition, during the charging and discharging process, the spinel structure LiMn2O4 will undergo irreversible phase transition to generate substances such as λ-MnO2, LiMn3O4, and rock salt structure MnO with a defective spinel structure. The continuous accumulation of irreversible phase transition will cause cracks in the lithium manganate particles, and the newly exposed surface caused by the particle cracks will interact with the electrolyte, thus promoting the dissolution of manganese from the lithium manganate. The manganese dissolution phenomenon is more obvious under high temperature conditions, and manganese dissolution is one of the main reasons for the poor cycle performance and poor high-temperature cycle performance of lithium manganate.

[0031] Based on the above considerations, in the present application, by coating a carbon coating layer containing a first metal element M on the surface of the lithium manganate, the crystal structure of the lithium manganate can be stabilized, the occurrence of manganese dissolution during the charging and discharging cycle process can be reduced, and the ionic conductivity and electronic conductivity of the lithium manganate can be improved. Specifically, by coating a metal-organic framework material on the surface of the core, the metal center of the metal-organic framework can be the first metal element M, and after heat treatment, the metal-organic framework material is carbonized to generate a carbon coating layer containing the first metal element M. The carbon coating layer containing the first metal element M has high electronic conductivity and fast lithium ion transport capacity, which can effectively hinder the direct contact between the liquid electrolyte and the positive active material particles, thereby inhibiting the dissolution of manganese; at the same time, the first metal element M can also stabilize the crystal structure of the positive active material, further inhibit the dissolution of manganese, and thus improve the cycle stability and rate performance of the positive active material.

[0032] In some embodiments, the lithium manganate coated with a carbon coating layer containing a first metal element on the surface has better ionic conductivity than the lithium manganate coated with a metal oxide on the surface, so that the lithium ion diffusion migration energy barrier is smaller, to a certain extent, reducing the internal polarization of the battery; it has better electronic conductivity, thereby reducing the difficulty of internal electron transport and improving the rate performance of the positive active material; during the charging and discharging process, i.e. Li +During the insertion and extraction process, the carbon coating layer has a good binding ability for the core, and the volume change of the carbon coating layer itself is also small. This makes it less likely for the positive electrode active material to pulverize and agglomerate during long cycles. In the later stages of cycling, it is less likely for the rate performance and cycle performance to decrease due to the formation of a new solid electrolyte film and the consumption of electrolyte. While hindering the contact between the liquid electrolyte and the positive electrode active material, it can also improve the electronic conductivity and ionic conductivity of the positive electrode active material.

[0033] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0034] In some embodiments, lithium manganese oxide may include lithium manganese oxide, nickel-cobalt-manganese ternary materials, and lithium-rich manganese-based solid solutions; lithium manganese oxide may also include other positive electrode active materials containing lithium manganese oxygen elements, such as lithium manganese phosphate.

[0035] In some embodiments, the positive electrode sheet includes a positive current collector and a positive active material layer located at least on one side of the positive current collector, wherein the positive active material layer includes a positive active material.

[0036] The batteries disclosed in this application can be used in electrical devices that use batteries as a power source, or in power systems that use batteries disclosed in this application to form such electrical devices, or in various energy storage systems that use batteries as energy storage elements. Electrical devices can include mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, while spacecraft can include airplanes, rockets, space shuttles, and spacecraft.

[0037] It should be understood that the technical solutions described in the embodiments of this application are not limited to the batteries and electrical devices described above, but can also be applied to all other electrical devices that include batteries and use batteries. However, for the sake of brevity, the following embodiments are all illustrated using electric vehicles as examples.

[0038] In the first aspect of this application, a positive electrode active material is proposed, with reference to Figure 1 It includes: a core 10, the core 10 comprising lithium manganese oxide; a carbon coating layer 20, the carbon coating layer 20 covering at least a portion of the surface of the core 10, the carbon coating layer 20 comprising a first metal element M (i.e., Figure 1As shown in Figure 21), the dissociation energy of the MO bond is greater than that of the Mn-O bond. When the dissociation energy of the MO bond is greater than that of the Mn-O bond, the MO bond has higher structural stability. When the first metal element enters the crystal lattice of the core, it will cause partial distortion of the crystal structure of the core, thereby expanding the lithium-ion insertion / extraction channel in the core, which is conducive to the diffusion of lithium ions in the core crystal structure. This can improve the ionic conductivity and crystal structure stability of the positive electrode active material. At the same time, the carbon coating layer can effectively improve the electron transfer efficiency and reduce the polarization phenomenon during the battery charging and discharging process, thereby further improving the cycle performance of the battery.

[0039] The dissociation energy of a chemical bond is the energy required to homogenize a chemical bond. Specifically, the process by which atoms form covalent bonds through the sharing of valence electrons and combine to form stable molecules is a process of energy reduction in the system, i.e., an energy release process. The energy released in this process is the bond energy of the chemical bond formed. When a chemical bond breaks, energy is required; the energy required to homogenize a chemical bond is the dissociation energy.

[0040] In some embodiments, the bond dissociation energy is common knowledge in the art, has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0041] In some embodiments, reference Figure 2 The core 10 may further include a first metal element M, which is located on the side surface of the core 10 near the carbon coating layer 20.

[0042] When the metal-organic framework material is carbonized to form a carbon coating layer through a high-temperature heating process, the first metal element M in the carbon coating layer 20 that is in contact with the core 10 will exchange elements with the manganese element in the core 10 at high temperature, and then enter the crystal structure of the core 10, thereby stabilizing the crystal structure of the core.

[0043] As an example, the first metal element in the core 10 exists in small amounts in the surface layer of the core 10. For example, when the number of moles of the first metal element in the core 10 is m3 and the number of moles of manganese in the core 10 is m4, the ratio of m3:m4 can be 0.001%-0.004%.

[0044] In some embodiments, the number of moles of any element in the compound is common knowledge in the art, has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0045] In some embodiments, the first metal element M may include at least one of Ti, Mg, Al, Cr, Ni, and Co; further, the first metal element M may include Al.

[0046] As an example, when the ionic radius of the first metal element is similar to that of manganese, during the high-temperature heating process of the metal-organic framework material, the first metal element M can be easily doped into the surface structure of the core 10 and replace Mn. 3+ The position of the first metallic element. While increasing the average valence state of manganese in the core, it can also decrease the valence state of Mn. 3+ The content of MO stabilizes the crystal structure of the core and suppresses the Jahn-Teller effect. Simultaneously, the dissociation energy of MO is greater than that of the Mn-O bond, thereby increasing the ionic conductivity of the core, reducing polarization, and improving the kinetic performance of the positive electrode active material.

[0047] In some embodiments, the valence state and average valence state of an element are common knowledge in the art, have common meanings in the art, and can be measured by test methods and instruments known in the art.

[0048] As an example, the Jahn-Teller effect refers to the distortion of high-energy orbitals in the electronic orbitals of a symmetric nonlinear molecule, which lowers the orbital energy and eliminates degeneracy. Taking spinel-structured lithium manganese oxide as an example, when the average valence state of Mn in spinel-structured lithium manganese oxide is lower than +3.5 during charging and discharging, Jahn-Teller distortion will occur, causing asymmetric expansion and contraction of the unit cell. This leads to a transformation of the spinel structure from cubic symmetry to tetragonal symmetry, resulting in an irreversible phase transition in the positive electrode active material, which in turn leads to a significant decrease in cycle performance.

[0049] In some embodiments, the introduction of a first metal element improves the crystal structure stability of lithium manganese oxide, which helps to suppress the occurrence of irreversible phase transitions of lithium manganese oxide at low discharge voltage platforms (such as less than 3V), effectively improving the discharge capability of lithium manganese oxide under low charge state, and thus improving the power performance of lithium manganese oxide.

[0050] In some embodiments, the carbon coating may include an oxide of a first metal element M.

[0051] As an example, when the carbon coating layer contains an oxide of the first metal element M, the oxide of the first metal element M near the core 10 reacts with the surface structure of the core to form a solid solution, thereby improving the stability of the core crystal structure and enhancing the high-temperature cycling performance and storage performance of the cathode active material. Taking lithium manganese oxide as the core and Ti as the first metal element, the oxide of titanium (titanium dioxide) near the core 10 reacts with the surface structure of the core to form LiMn. 2-q A solid solution of TiO2, wherein 0 ≤ q ≤ 0.2.

[0052] In some embodiments, the lithium manganese oxide may include at least one of a lithium-rich manganese-based solid solution, a nickel cobalt manganese ternary material, lithium manganese phosphate, and lithium manganate.

[0053] As an example, the lithium manganese oxide has a low production cost and a high discharge specific capacity.

[0054] In some embodiments, the lithium-rich manganese-based solid solution may satisfy the general formula: xLi a [Li 1 / 3 Mn 2 / 3 O b ·(1 - x)Li c M1O d where 0 < x < 1, 0.9 ≤ a + c ≤ 1.2, 1.0 ≤ b + d ≤ 2.5, and M1 includes at least one of Al, Mn, Cr, Co, Ni, Fe, and Ru.

[0055] As an example, x may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; a + c may be 0.9, 1.0, 1.1, or 1.2; b + d may be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or 2.5.

[0056] In some embodiments, the nickel cobalt manganese ternary material may satisfy the general formula: Li e Ni f Co g Mn h M2 i O j where 0.9 ≤ e ≤ 1.2, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 ≤ i ≤ 0.2, f + g + h + i = 1, 1.0 ≤ j ≤ 2.5, and M2 includes at least one of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and Al.

[0057] As an example, f may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; g may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; h may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; i may be 0, 0.1, 0.15, or 0.2; j may be 1.0,​​In some embodiments, lithium manganese phosphate can satisfy the general formula: Li k Mn 1-m M3 m PO n Where 0.9≤k≤1.2, 0≤m≤0.8, 3.0≤n≤4.5, and M3 includes one of Al, Fe, Ti, Mg, V, Mn, Cr, Zr, Nb, and W.

[0059] As an example, k can be 0.9, 1.0, 1.1, or 1.2; m can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8; and n can be 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, or 4.5.

[0060] In some embodiments, lithium manganese oxide can satisfy the general formula: Li p Mn 2-q M4 q O s Wherein, 0.9≤p≤1.2, 0≤q≤0.2, 3.0≤s≤4.5; M4 includes at least one of Li, Cr, Co, Ni, Mg, Ca, Sr, Ba, Na, K, Al, Be, B, Ti, Zr, Cu, Zn, Ga, Sn, and V.

[0061] It is understandable that the dopant elements M1, M2, M3, and M4 can be dopant elements contained in the core itself, or they can be dopant elements introduced by the first metal element in the carbon coating layer.

[0062] As an example, p can be 0.9, 1.0, 1.1 or 1.2; q can be 0, 0.1, 0.15 or 0.2; s can be 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4 or 4.5.

[0063] In some embodiments, the chemical formula of the compound is common knowledge in the art, has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0064] In some embodiments, the kernel particle size can be 7μm-15μm, and optionally, the kernel particle size can be 9μm-12μm.

[0065] As an example, the kernel particle size can be 7μm, 7.2μm, 7.5μm, 7.8μm, 8μm, 8.2μm, 8.5μm, 8.8μm, 9μm, 9.2μm, 9.5μm, 9.8μm, 10μm, 10.2μm, 10.5μm, 10.8μm, 11μm, 11.2μm, 11.5μm, 11.8μm, 12μm, 12.2μm, 12.5μm, 12.8μm, 13μm, 13.2μm, 13.5μm, 13.8μm, 14μm, 14.2μm, 14.5μm, 14.8μm, or 15μm.

[0066] In some embodiments, the kernel size is common knowledge in the art, has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0067] As an example, the core particle size can be obtained by testing as follows: The testing instrument is a JEM-2100 high-resolution transmission electron microscope, the accelerating voltage is 300kV, and the resolution is 0.1nm-0.2nm. 10mg of the positive electrode active material to be tested is uniformly dispersed in anhydrous ethanol. Then, the suspension is added to the surface of a microgrid copper mesh, dried, and then tested using a transmission electron microscope. The core particle size is obtained by observing the copper mesh under the transmission electron microscope.

[0068] As an example, when the core particle size is 7μm-15μm, the core particles have a moderate size, the positive electrode slurry has high stability, and it is not easy to have defects such as sedimentation and poor slurry consistency. During the coating process of the positive electrode slurry, it is not easy to have defects such as material blockage, particle scratches, and pitting after the electrode is dried, which will lead to electrode quality problems. At the same time, the specific surface area of ​​the core is moderate, with fewer surface defects, and the core powder is not easy to agglomerate and induce battery polarization.

[0069] In some embodiments, see Figure 2 The thickness of the carbon coating is d1, and the particle size of the core is d2. The ratio of d1 to d1 can be 0.01-0.1.

[0070] As an example, d1:d1 can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1.

[0071] When d1:d1 is 0.01-0.1, the thickness of the carbon coating layer is moderate, which can effectively reduce the direct contact between the electrolyte and the positive electrode active material, thereby reducing the occurrence of side reactions and manganese dissolution, while not hindering the diffusion and migration of lithium ions between the core 10 and the electrolyte interface.

[0072] In some embodiments, the thickness of the carbon coating is common knowledge in the art and has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0073] As an example, the thickness of the carbon coating can be obtained by referring to the test method of core particle size. For example, the positive electrode active material to be tested can be dispersed in anhydrous ethanol and then dropped onto the surface of a copper mesh. After drying, the copper mesh can be observed under a transmission electron microscope to obtain the thickness of the carbon coating.

[0074] In some embodiments, the mass fraction of the carbon coating layer in the positive electrode active material can be 1%-3%.

[0075] As an example, the mass fraction of the carbon coating layer in the positive electrode active material can be 1%, 1.5%, 2%, 2.5%, or 3%. When the mass fraction of the carbon coating layer in the positive electrode active material is 1%-3%, the proportion of the coating layer in the positive electrode active material is more appropriate. It can suppress the side reactions between lithium manganese oxide and electrolyte, and has little impact on the specific capacity and energy density of the positive electrode active material.

[0076] In some embodiments, the mass fraction of the carbon coating layer in the positive electrode active material is common knowledge in the art and has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0077] As an example, the mass fraction of the carbon coating layer in the positive electrode active material can be obtained by the reaction between the acid solution and the positive electrode active material. Specifically, a quantitative amount of the positive electrode active material to be tested can be dissolved in hydrochloric acid, filtered, washed with deionized water, dried and weighed to obtain the mass of the carbon coating layer. The mass fraction of the carbon coating layer in the positive electrode active material can be obtained by dividing the mass of the carbon coating layer by the total mass of the positive electrode active material.

[0078] In some embodiments, the number of moles of the first metal element M in the carbon coating layer is m1, and the number of moles of manganese element in the core is m2, where m1:m2 can be 0.01%-0.5%.

[0079] In some embodiments, the number of moles of any element in the carbon coating layer is common knowledge in the art and has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0080] As an example, the number of moles of the first metal element in the carbon coating layer can be obtained by the following method: use a scanning electron microscope to perform elemental analysis on the carbon coating layer of the positive electrode active material, measure the weight percentage of the first metal element in the carbon coating layer, and calculate the number of moles based on the molar mass of the corresponding element.

[0081] In some embodiments, the number of moles of any element in the kernel is common knowledge in the art, has a common meaning in the art, and can be measured by test methods and instruments known in the art.

[0082] As an example, the number of moles of manganese in the core can be determined by the following method: a certain amount of positive electrode active material is nitrated with a strong acid to leach manganese from the core, and then the number of moles of manganese can be measured using an inductively coupled plasma spectrometer (ICP).

[0083] As an example, m1:m2 can be 0.01%, 0.03%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. By introducing a small amount of the first metallic element, the stability of the core crystal structure can be effectively improved while retaining the original core structure.

[0084] In a second aspect of this application, a method for preparing the aforementioned positive electrode active material is provided, comprising: S100: Hybridizing the core with metal-organic framework materials In some embodiments, the core is mixed with a metal-organic framework material in this step to obtain a precursor. Specifically, the mass fraction of the metal-organic framework material in the precursor can be 1%-5%.

[0085] As an example, the mass fraction of metal-organic framework material in the precursor can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0086] Metal-organic frameworks (MOFs) are materials with one-dimensional, two-dimensional, or three-dimensional structures formed by coordination bonds between a metal center and organic ligands.

[0087] In some embodiments, the metal center of the metal-organic framework material may include at least one of Ti, Mg, Al, Cr, Ni, and Co. The type of the first metal element in the carbon coating layer formed by the metal-organic framework can be adjusted by modifying the metal center.

[0088] In some embodiments, the organic ligands of the metal-organic framework material may include at least one of terephthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2-di(4-pyridyl)ethylene, 1,3,5-tris(4-carboxyphenyl)benzene, 2,2'-bipyridine, 2,5-dihydroxyterephthalic acid, and ethyl 2,5-dihydroxyterephthalate.

[0089] As an example, metal-organic frameworks can include at least one of MOF-74 (Mg), MIL-53 (Cr), Ni-MOF-74, Co-ZIF-9, MIL-125 (Ti), and MIL-53 (Al). By leveraging the tunable properties of the metal center and organic ligands in MOFs, MOF materials with tunable pore structures can be obtained. This facilitates the adjustment of structural parameters such as the first metal element of the final carbon coating, coating density, and coating porosity, achieving high conductivity and high crystal structure stability while minimizing the impact on lithium-ion insertion and extraction.

[0090] S200: Heat treatment of the precursor In some embodiments, the precursor is heat-treated to obtain a positive electrode active material. The heat treatment of the precursor can generate lithium manganese oxide coated with a carbon coating layer containing a first metal element in one step.

[0091] In some embodiments, the heating treatment includes a heating treatment, a holding treatment, and a cooling treatment, wherein the heating treatment satisfies at least one of the following conditions: the heating rate of the heating treatment is 2°C / min-8°C / min, and the maximum temperature of the heating treatment is 450°C-900°C; the holding time is 10h-15h, and the holding temperature is the maximum temperature of the heating treatment; the cooling rate of the cooling treatment is 4°C / min-10°C / min, and the minimum temperature of the cooling treatment is less than or equal to 200°C.

[0092] As an example, the heating rate of the heating process can be 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, or 8℃ / min; the maximum temperature of the heating process can be 450℃, 500℃, 550℃, 600℃, 650℃, 7000℃, 750℃, 800℃, 850℃, or 900℃. By adjusting the heating rate and the maximum temperature reached, energy consumption can be reduced, the preparation time can be shortened, and thus production efficiency can be improved.

[0093] In some embodiments, different heating temperatures affect the formation of crystal faces in lithium manganese oxide. When the maximum temperature of the heating treatment is 500°C, it is easier to form a crystal structure with more (111) crystal faces. The (111) crystal faces help to improve the structural stability of the crystal, thereby improving the cycle stability of the positive electrode active material.

[0094] In some embodiments, when the maximum temperature of the heating process is greater than 900°C, that is, when the temperature of the heat preservation process is greater than 900°C, such as 1000°C, 1200°C or 1500°C, although a crystal structure with a better crystal orientation can be generated, it will result in a large amount of energy consumption and the requirements for production equipment will be greatly increased.

[0095] As an example, the heat preservation treatment is carried out at the highest temperature reached during the heating treatment, and the heat preservation treatment time can be 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h, 14.5h or 15h.

[0096] As an example, the cooling rate for the cooling process can be 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min. A faster cooling rate can improve the stability of the crystal structure of the positive electrode active material and reduce the crystal phase transformation that occurs during the cooling process. The minimum temperature for the cooling process can be less than or equal to 200℃. When the temperature drops below 200℃, the crystal structure of the positive electrode active material is relatively stable and less prone to re-processing. Subsequent cooling can then be performed using room temperature cooling.

[0097] It should be noted that the relevant parameters in the above method for preparing positive electrode active materials can refer to some or all of the technical features in the foregoing embodiments. The parts of the method for preparing positive electrode active materials that are not described in the relevant embodiments can also refer to the foregoing embodiments and related figures, and will not be repeated here.

[0098] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0099] In a third aspect of this application, a battery is provided, including a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer located at least on one side of the positive current collector, the positive active material layer including the aforementioned positive active material, and / or the positive active material prepared by the aforementioned method.

[0100] In the embodiments of this application, battery 5 can be a metal battery, for example, battery 5 can be a lithium metal battery, etc.

[0101] In some embodiments, the electrode assembly includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode.

[0102] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound together to form the wound structure.

[0103] In some embodiments, the electrode assembly has a stacked structure.

[0104] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0105] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0106] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0107] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0108] As an example, the separator can be continuously installed between any adjacent positive or negative electrode plates by folding or rolling.

[0109] In some embodiments, the electrode assembly may be cylindrical, flat, or polygonal, etc.

[0110] In some embodiments, the electrode assembly has tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0111] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0112] As an example, the positive electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0113] In some embodiments, the negative electrode sheet may include a negative current collector, which may be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc., may be used. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0114] In some embodiments, the negative electrode sheet may be a rolled metal foil or a metal powder coated with an inert layer may be applied to the current collector.

[0115] In some embodiments, the negative electrode current collector can be a composite current collector. For example, the composite current collector may include at least one of carbon cloth, carbon film, carbonaceous material, porous current collector, alloy-modified current collector, lithium-loving modified current collector, and sodium-loving modified current collector.

[0116] In some embodiments, the negative electrode sheet may include a negative current collector and a negative active material layer disposed on at least one side of the negative current collector. The negative active material layer may include a negative active material, which may be a high specific capacity material. For example, the negative active material may include at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate.

[0117] As an example, silicon-based materials may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy materials; tin-based materials may include at least one of elemental tin, tin oxide, and tin alloy materials.

[0118] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any porous separator membrane with good chemical and mechanical stability can be selected.

[0119] As an example, the main material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, ceramic, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component located between the positive and negative electrode plates, or it can be attached to the surfaces of the positive and negative electrodes.

[0120] As an example, this application does not impose any particular limitation on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 This is a square-structured battery 5 as an example. Specifically, refer to... Figure 4 The outer packaging of battery 5 may include a housing 51 and a top cover assembly 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be placed over the opening to close the receiving cavity.

[0121] As an example, the positive electrode, negative electrode, and separator can be formed into electrode assembly 52 by a winding or stacking process. Electrode assembly 52 is encapsulated within a receiving cavity, and a gel polymer electrolyte fills the internal space of electrode assembly 52. ​​The battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0122] As an example, batteries can be assembled into battery modules, and the number of batteries contained in a battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module. Figure 5 This is battery module 4, used as an example. (See reference...) Figure 5 In battery module 4, multiple batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple batteries 5 can be fixed in place by fasteners. Battery module 4 may also include a housing with a receiving space in which the multiple batteries 5 are received.

[0123] As an example, the battery modules described above can also be assembled into a battery pack. The number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack. Figure 6 and Figure 7 This is battery pack 1 as an example. (See reference...) Figure 6 and Figure 7 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0124] In a fourth aspect, this application proposes an electrical device including the aforementioned battery 5. Therefore, this electrical device possesses all the features and advantages of the aforementioned battery 5, which will not be repeated here.

[0125] Batteries, battery modules, or battery packs can serve as power sources for electrical devices or as energy storage units for those devices. Electrical devices can include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Electrical devices can select batteries, battery modules, or battery packs based on their usage requirements.

[0126] As an example, Figure 8 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0127] As an example, electrical devices could also be mobile phones, tablets, laptops, etc. These devices typically require a slim and lightweight design and can use batteries as their power source.

[0128] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0129] Example 1 1. Preparation of positive electrode active materials MIL-125 (Ti) powder was mixed with lithium manganese oxide cathode material to obtain a precursor, wherein the mass fraction of metal-organic framework (MOF) material in the precursor was 3 wt%. The precursor was milled at 300 r / min for 5 h using a high-energy ball mill, and then heated to 500 °C at a heating rate of 5 °C / min and held for 12 h in an air atmosphere (oxygen-containing atmosphere), followed by cooling to 200 °C at a cooling rate of 5 °C / min, and then naturally cooled to room temperature to obtain the cathode active material.

[0130] 2. Preparation of the positive electrode sheet The obtained positive electrode active material, conductive agent (carbon black), binder (polyvinylidene fluoride (PVDF)), and solvent (N-methylpyrrolidone (NMP)) were mixed evenly in a weight ratio of 95.48:1.47:1.55:1.14 to obtain a positive electrode slurry. The positive electrode slurry was then uniformly coated onto the positive electrode current collector (aluminum foil) at a coating density of 0.35 g / 1540 mm². 2 After cold pressing, a positive electrode sheet is obtained.

[0131] 3. Preparation of negative electrode sheet The negative electrode active material (graphite), conductive agent (carbon black), binder (styrene-butadiene rubber (SBR)), and thickener (sodium carboxymethyl cellulose (CMC)) were dissolved in deionized water at a weight ratio of 97.2:0.8:0.8:1.2. After thorough mixing, a negative electrode slurry was obtained. The negative electrode slurry was then coated onto a negative electrode current collector (copper foil) at a coating density of 0.175 g / 1540 mm². 2 After cold pressing, a negative electrode sheet is obtained.

[0132] 4. Preparation of electrolyte In an argon-atmospheric glove box, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed uniformly in a volume ratio of 36:29:35 to obtain a mixed solvent. 1M LiPF6 lithium salt is then dissolved in the mixed solvent and stirred until homogeneous to obtain an electrolyte.

[0133] 5. Battery manufacturing Using a polypropylene film as the separator, the positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a barrier between the positive and negative electrodes. The resulting bare cell is then wound, tabs are welded onto it, and the cell is placed in an aluminum casing. It is then baked at 100°C to remove moisture, followed by the injection of the aforementioned electrolyte and sealing, resulting in a non-charged battery. The non-charged battery then undergoes a series of processes including settling, hot and cold pressing, formation, and shaping to obtain the final battery.

[0134] Examples 2-16, Comparative Examples 1-2, and the preparation of the positive electrode, negative electrode, electrolyte, and battery in Examples 1 are all the same. The difference lies in the preparation of the positive electrode active material, as detailed in Table 1. In Comparative Example 1, the core was not modified with carbon coating, and in Comparative Example 2, the core was simply mixed with MOF without heat treatment.

[0135] Table 1

[0136] The positive electrode active materials in Examples 1-16 and Comparative Examples 1-2 were subjected to the following tests, and the test results are shown in Table 2. 1. Thickness of carbon coating layer: The positive electrode active material to be tested is dispersed in anhydrous ethanol and then dropped onto the surface of a copper mesh. After drying, the copper mesh is observed under a transmission electron microscope to obtain the thickness of the carbon coating layer.

[0137] 2. Number of moles of the first metal element in the carbon coating layer: Elemental analysis of the carbon coating layer of the positive electrode active material is performed using a scanning electron microscope to determine the weight percentage of the first metal element in the carbon coating layer. The number of moles can be obtained by converting the molar mass of the corresponding element.

[0138] 3. Number of moles of manganese in the core: A certain amount of positive electrode active material is nitrated with a strong acid to leach manganese from the core. The number of moles of manganese can then be measured using an inductively coupled plasma spectrometer (ICP).

[0139] 4. Mass fraction of carbon coating in positive electrode active material: After dissolving the positive electrode active material to be tested in hydrochloric acid, filter, wash with deionized water, dry and weigh to obtain the mass of carbon coating. Divide the mass of carbon coating by the total mass of positive electrode active material to obtain the mass fraction of carbon coating in positive electrode active material.

[0140] 5. Testing of Ionic and Electronic Conductivity: The positive electrode active material powder was placed in a battery test mold with a liner, and stainless steel gaskets were used as blocking electrodes on both sides. The mold battery was pressed at 350 MPa for 3 minutes to produce conductivity model batteries. Ionic conductivity was tested using the AC impedance module of an electrochemical workstation; electronic conductivity was obtained by constant voltage DC testing of the model battery using the electrochemical workstation. The calculation formula is shown below:

[0141] Where σ represents conductivity, d represents the thickness of the electrode under test, R represents electrochemical impedance (both ionic and electronic impedance values ​​are measured by an electrochemical workstation), and S represents the effective area of ​​the electrode under test.

[0142] Table 2

[0143] The following tests were performed on the batteries in Examples 1-16 and Comparative Examples 1-2, and the test results are shown in Table 3. 1. High-rate capacity retention test At 25℃, the battery is charged to 4.4V at a constant current of 1 / 3C, then charged to a current of 0.05C at a constant voltage of 4.4V. After resting for 5 minutes, it is discharged to 2.5V at 1 / 3C. The resulting capacity is recorded as the initial capacity C0. The battery is then charged to 4.4V again at a constant current of 1 / 3C, then charged to a current of 0.05C at a constant voltage of 4.4V. After resting for 5 minutes, it is discharged to 2.5V at 4C. After one cycle, the resulting capacity is recorded as the initial capacity C1. C1 / C0 is the high-rate capacity retention rate.

[0144] 2. Cyclic capacity retention test At 45°C, the battery is charged at a constant current of 1 / 3C to 4.4V, then charged at a constant voltage of 4.4V to a current of 0.05C. After resting for 5 minutes, it is discharged at 1 / 3C to 2.5V. The resulting capacity is recorded as the initial capacity C0. The above steps are repeated for the same battery, and the discharge capacity C of the battery after the nth cycle is recorded. n Then, the battery capacity retention rate P after each cycle n =C n / C0×100%, when n is 500, record P. 500 As the cycle capacity retention rate of the battery.

[0145] 3. Mn dissolution ICP test The fully charged negative electrode sheet, after 500 cycles, was disassembled, and the Mn content in the negative electrode sheet was tested using inductively coupled plasma (ICP) to confirm the extent of manganese dissolution.

[0146] Table 3

[0147] In the description of this specification, references to terms such as "one embodiment," "another embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. The illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0148] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A battery, characterized in that, It includes a positive electrode plate and a negative electrode plate; The positive electrode plate includes a positive current collector and a positive active material layer at least on one side of the positive current collector, and the positive active material layer includes a positive active material; The positive active material includes: A core, and the core includes lithium manganese oxide; A carbon coating layer that at least covers a part of the surface of the core, and the carbon coating layer includes a first metal doping element M, and the dissociation energy of the M-O bond is greater than that of the Mn-O bond; The negative electrode plate includes a negative active material layer, the negative active material layer includes a negative active material, and the negative active material includes at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate.

2. The battery according to claim 1, characterized in that, The core further includes the first metal element M, and the first metal element M is located on the surface of the core close to the carbon coating layer.

3. The battery according to claim 1 or 2, characterized in that, The first metal element M includes at least one of Ti, Mg, Al, Cr, Ni, and Co.

4. The battery according to claim 3, characterized in that, The first metal element M includes Al.

5. The battery according to any one of claims 1-4, characterized in that, The carbon coating layer includes an oxide of the first metal element M.

6. The battery according to any one of claims 1-5, characterized in that, The lithium manganese oxide includes at least one of lithium-rich manganese-based solid solution, nickel cobalt manganese ternary material, lithium manganese phosphate, and lithium manganate.

7. The battery according to claim 6, characterized in that, The lithium manganese oxide satisfies at least one of the following conditions: The lithium-rich manganese-based solid solution satisfies the general formula: xLi a [Li 1 / 3 Mn 2 / 3 O b ·(1-x)Li c M1O d , Where 0 < x < 1, 0.9 ≤ a + c ≤ 1.2, 1.0 ≤ b + d ≤ 2.5, and M1 includes at least one of Al, Mn, Cr, Co, Ni, Fe, and Ru; The nickel-cobalt-manganese ternary material satisfies the general formula: Li e Ni f Co g Mn h M2 i O j , Where 0.9 ≤ e ≤ 1.2, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 ≤ i ≤ 0.2, f + g + h + i = 1, 1.0 ≤ j ≤ 2.5, and M2 includes at least one of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and Al; The lithium manganese phosphate satisfies the general formula: Li k Mn 1-m M3 m PO n , Where 0.9 ≤ k ≤ 1.2, 0 ≤ m ≤ 0.8, 3.0 ≤ n ≤ 4.5, and M3 includes one of Al, Fe, Ti, Mg, V, Mn, Cr, Zr, Nb, and W; The lithium manganese oxide satisfies the general formula: Li p Mn 2-q M4 q O s , Where 0.9 ≤ p ≤ 1.2, 0 ≤ q ≤ 0.2, 3.0 ≤ s ≤ 4.5; and M4 includes at least one of Li, Cr, Co, Ni, Mg, Ca, Sr, Ba, Na, K, Al, Be, B, Ti, Zr, Cu, Zn, Ga, Sn, and V.

8. The battery according to any one of claims 1-7, characterized in that, The particle size of the core is 7 μm - 15 μm.

9. The battery according to claim 8, characterized in that, The particle size of the core is 9 μm - 12 μm.

10. The battery according to any one of claims 1-9, characterized in that, The thickness of the carbon coating layer is d1, and the particle size of the core is d2, and d1:d2 is 0.01 - 0.

1.

11. The battery according to any one of claims 1-10, characterized in that, The mass fraction of the carbon coating layer in the positive active material is 1% - 3%.

12. The battery according to any one of claims 1-11, characterized in that, The molar number of the first metal element M in the carbon coating layer is m1, and the molar number of the manganese element in the core is m2, and m1:m2 is 0.01% - 0.5%.

13. The battery according to any one of claims 1-12, characterized in that, The negative active material layer includes the negative active material, a conductive agent, a binder, and a thickening agent.

14. An electrical appliance, characterized in that, It includes the battery according to any one of claims 1 - 13.

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