Battery cell and preparation method therefor, positive electrode active material and preparation method therefor, positive electrode sheet, battery apparatus, and electric apparatus

Abstract

Disclosed in the present application are a battery cell and a preparation method therefor, a positive electrode active material and a preparation method therefor, a positive electrode sheet, a battery apparatus, and an electric apparatus. The battery cell comprises a positive electrode sheet, the positive electrode sheet comprising a current collector and a positive electrode active material layer provided on at least one side of the current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising an O3-type layered metal oxide, and the layered metal oxide comprising a Ti element; in a positive electrode active material particle containing the layered metal oxide, the Ti element is distributed inside the particle and on a surface of the particle, and a distribution concentration of the Ti element inside the particle is greater than a distribution concentration of the Ti element on the surface of the particle. This allows for voltage windows of a positive electrode active material and a battery cell to be increased while maintaining the cycle stability of the positive electrode active material, and improves battery cell energy density.

Description

Battery cell and preparation method thereof, positive electrode active material and preparation method thereof, positive electrode sheet, battery device, and electric device

[0001] Priority information

[0002] The present application claims priority to and the benefit of Chinese Patent Application No. 202411389508.5, filed September 30, 2024, and is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the technical field of batteries, and in particular, relates to a battery cell and a preparation method thereof, a positive electrode active material and a preparation method thereof, a positive electrode sheet, a battery device, and an electric device. BACKGROUND

[0004] Secondary batteries are not only applied to energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, and electric transportation tools, military equipment, aerospace, and other fields. Sodium-ion batteries are a kind of secondary batteries, which mainly rely on the movement of sodium ions between the positive and negative electrodes to work. Sodium-ion layered oxides are commonly used positive electrode active materials for sodium-ion batteries. With the development of the current society, people have increasingly high requirements for batteries. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a battery cell, aiming to balance the high working voltage and cycle stability of the positive electrode active material and the battery cell, and improve the energy density of the battery cell.

[0006] To achieve the above-mentioned purpose, the first aspect of the present application provides a battery cell, comprising:

[0007] A positive electrode sheet, the positive electrode sheet comprising a current collector and a positive electrode active material layer provided on at least one side of the current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising a layered metal oxide of O3 phase, the layered metal oxide comprising a Ti element; in the positive electrode active material particles containing the layered metal oxide, the Ti element is distributed in the particle interior and the particle surface, and the distribution concentration of the Ti element in the particle interior is greater than that on the particle surface.

[0008] The positive electrode active material of the first aspect of the present application at least has the following beneficial effects: it can improve the voltage window of the positive electrode active material and the battery cell while balancing the cycle stability of the positive electrode active material, and improve the energy density of the battery cell.

[0009] In some embodiments of the present application, the layered metal oxide comprises Na x Zny Ni z Ti a Mn b Fe c Cu d M e O 2±f Wherein, 0.8≤x<1.1; 0<y≤0.1; 0<z≤0.4; 0.05≤a≤0.25; 0<b≤0.5; 0<c≤0.3; 0<d≤0.1; 0≤e≤0.1; y+z+a+b+c+d+e=1; 0≤f≤0.05; M includes one or more of the following elements: Li, Mg, Ca, Zr, Co, Al. This is beneficial for further improving the energy density of battery cells while considering both the cycle stability and high voltage window of the positive electrode active material.

[0010] In some embodiments of this application, 0.05 ≤ a ≤ 0.15.

[0011] In some embodiments of this application, 0.03 ≤ y ≤ 0.08. This further balances the cycle stability and high voltage window of the positive electrode active material, thereby improving the energy density of the battery cell.

[0012] In some embodiments of this application, 0.02 ≤ d ≤ 0.05. This further balances the cycle stability and high voltage window of the positive electrode active material, thereby improving the energy density of the battery cell.

[0013] In some embodiments of this application, 0.1 ≤ a + y + d ≤ 0.25. This further balances the cycle stability and high voltage window of the positive electrode active material, thereby improving the energy density of the battery cell.

[0014] In some embodiments of this application, in the positive electrode active material particles containing the layered metal oxide, the concentration of Ti element distribution decreases from the inside to the outside of the particles.

[0015] In some embodiments of this application, the Dv50 particle size of the positive electrode active material is 6 μm to 10 μm. This is beneficial for the positive electrode active material to have suitable compaction density and specific surface area, which in turn helps to further enable the battery cell to achieve both high energy density and good cycle performance.

[0016] In some embodiments of this application, the compaction density of the positive electrode active material under 3 tons of pressure is 3.0 g / cm³. 3 ~3.15g / cm 3 This helps to achieve a higher compaction density in the positive electrode active material layer, which in turn helps to further improve the energy density of the battery cell.

[0017] In some embodiments of this application, the voltage window of the battery cell is 1.5V to 4.15V, and the upper limit operating voltage of the battery cell is 3.95V to 4.15V.

[0018] A second aspect of this application provides a positive electrode active material comprising: a layered metal oxide of the O3 phase, wherein the layered metal oxide includes Ti; in the positive electrode active material particles containing the layered metal oxide, Ti is distributed both inside and on the surface of the particles, and the concentration of Ti inside the particles is greater than its concentration on the surface of the particles. This allows for a balance between good cycle stability and a high voltage window, improving the energy density of the battery cell.

[0019] In some embodiments of this application, the layered metal oxide includes Na. x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f Wherein, 0.8≤x<1.1; 0<y≤0.1; 0<z≤0.4; 0.05≤a≤0.25; 0<b≤0.5; 0<c≤0.3; 0<d≤0.1; 0≤e≤0.1; y+z+a+b+c+d+e=1; 0≤f≤0.05; M includes one or more of the following elements: Li, Mg, Ca, Zr, Co, Al.

[0020] In some embodiments of this application, the layered metal oxide satisfies at least one of the following conditions: 0.05≤a≤0.15, 0.03≤y≤0.08, 0.02≤d≤0.05, 0.1≤a+y+d≤0.25.

[0021] A third aspect of this application provides a method for preparing a positive electrode active material, comprising: preparing precursor particles containing a metal element; mixing the precursor particles with a sodium source and a metal source and subjecting them to a first calcination treatment, wherein: the metal element includes Ti, and the metal source includes a Ti source; in the precursor particles, the molar percentage of Ti, based on the total molar amount of the metal element, is n1; in the metal source, the molar percentage of Ti, based on the total molar amount of the metal element, is n2, where n2 < n1. This method can balance the cycle stability and high voltage window of the positive electrode active material, thereby improving the energy density of the battery cell.

[0022] In some embodiments of the present application, the metal elements include Ni elements, Mn elements, Fe elements, Zn elements, Ti elements and Cu elements; the metal sources include nickel sources, manganese sources, iron sources, zinc sources, titanium sources and copper sources; in the precursor particles, the mole percentage of the Ti elements is n1, based on the total mole amount of the Ni elements, the Mn elements, the Fe elements, the Zn elements, the Ti elements and the Cu elements; in the metal sources, the mole percentage of the Ti elements is n2, based on the total mole amount of the Ni elements, the Mn elements, the Fe elements, the Zn elements, the Ti elements and the Cu elements, and n2 < n1. In this way, the cycle stability and the high-voltage window of the positive electrode active material can be further considered, and the energy density of the battery cell can be improved.

[0023] In some embodiments of the present application, the method for preparing the positive electrode active material further includes: performing a second calcination treatment on the first calcination product, and the temperature of the second calcination treatment is greater than the temperature of the first calcination treatment. In this way, the raw material components can be first converted into layered metal oxides, and then the phase state of the layered metal oxides can be converted into O3 phase through the second calcination, so as to obtain the layered metal oxides in O3 phase.

[0024] In some embodiments of the present application, the temperature of the first calcination treatment is 650-950℃, and the time is 5-20h.

[0025] In some embodiments of the present application, the temperature of the second calcination treatment is 700-1000℃, and the time is 5-20h.

[0026] In some embodiments of the present application, the precursor particles are prepared by using a co-precipitation method or a mechanical ball milling method.

[0027] In some embodiments of the present application, in the precursor particles, the distribution concentration of the Ti elements presents a decreasing trend from inside to outside.

[0028] The fourth aspect of the present application provides a positive electrode tab, which includes the positive electrode active material provided in the second aspect of the present application or the positive electrode active material prepared by using the method provided in the third aspect of the present application.

[0029] The fifth aspect of the present application provides a method for preparing a battery cell, comprising: mixing a positive electrode active material, a conductive agent and a binder with a solvent to obtain a positive electrode slurry; coating the positive electrode slurry on at least one side of a current collector to obtain a positive electrode sheet, wherein the positive electrode active material comprises a layered metal oxide of O3 phase, and the layered metal oxide comprises Ti element; and in the positive electrode active material particles containing the layered metal oxide, the distribution concentration of Ti element inside the particles is greater than that on the surface of the particles. In this way, the voltage window of the positive electrode active material and the battery cell can be improved on the basis of considering the cycle stability of the positive electrode active material, and the energy density of the battery cell can be improved.

[0030] In some embodiments of the present application, the layered metal oxide comprises Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f , wherein 0.8≤x<1.1; 0

[0031] The sixth aspect of the present application provides a battery device, comprising: the battery cell of the first aspect of the present application, or the positive electrode active material of the second aspect of the present application, or the positive electrode active material prepared by the method of the third aspect of the present application, or the positive electrode sheet of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application.

[0032] The seventh aspect of the present application provides a power utilization device, comprising: the battery cell of the first aspect of the present application, or the electrode sheet of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application, or the battery device of the sixth aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0033] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0034] FIG. 1 is a structural schematic diagram of a battery according to an embodiment of the present application.

[0035] FIG. 2 is a structural schematic diagram of a battery module according to an embodiment of the present application.

[0036] FIG. 3 is a schematic diagram of a structure of a battery pack according to an embodiment of the present application.

[0037] FIG. 4 is an exploded view of FIG. 3.

[0038] FIG. 5 is a schematic diagram of a use device using the battery according to an embodiment of the present application as a power source.

[0039] FIG. 6 is a graph showing a comparison of changes in discharge voltage with an increase in cycle number of battery cells produced in Example 1 and Comparative Example 1 of the present application.

[0040] BRIEF DESCRIPTION OF DRAWINGS 1: battery; 2: battery module; 3: battery pack; 4: upper case; 5: lower case. DETAILED DESCRIPTION

[0041] The present application will be further described with reference to the specific embodiments. It is to be understood that these embodiments are merely illustrative of the present application and do not limit the scope of the present application.

[0042] In the present application, the phrase "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily mutually exclusive of other embodiments. It is explicitly and implicitly understood that the embodiments described herein are combinable with each other.

[0043] The "ranges" disclosed herein are defined by both a lower and / or upper limit, the given range is defined by selecting a lower limit and / or an upper limit, the selected lower limit and / or upper limit define the boundaries of the particular range. The ranges defined by such limits can be either inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range not explicitly recited, and any lower limit can be combined with any other lower limit to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each individual point or single numerical value can itself serve as a lower limit or an upper limit to combine with any other point or single numerical value, or to combine with other lower limits or upper limits, to form a range not explicitly recited.

[0044] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0045] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0046] If there is no special description, all steps of the present application can be carried out in sequence, or randomly, preferably in sequence. For example, the method comprises steps S1 and S2, which means that the method can comprise steps S1 and S2 in sequence, or steps S2 and S1 in sequence. For example, the method also comprises step S3, which means that step S3 can be added to the method in any order, for example, the method can comprise steps S1, S2 and S3, or steps S1, S3 and S2, or steps S3, S1 and S2, etc.

[0047] If there is no special description, in the present application, the term "and / or" is only a description of the association between the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this paper generally means that the front and rear associated objects are a "or" relationship.

[0048] In the present application, the terms "a plurality of" and "a plurality of" refer to two or more than two.

[0049] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as understood by a person skilled in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing the specific embodiments of the present application, and are not intended to limit the present application; the terms "include" and "have" in the specification and claims of the present application and any modification thereof are intended to cover non-exclusive inclusion. Unless otherwise stated, the terms used in the present application have the commonly understood meaning by those skilled in the art. Unless otherwise stated, the values of the parameters mentioned in the present application can be measured by various measurement methods commonly used in the art (for example, the method can be tested according to the method given in the examples of the present application).

[0050] With the continuous promotion of the green environmental protection theme, the application of batteries has penetrated into all aspects of life, including vehicles, electronic devices, energy storage devices, etc. However, as the application of batteries continues to expand, people's requirements for batteries are also getting higher and higher. For example, sodium-ion batteries, which are expected to have high energy density. Currently, the improvement of the energy density of sodium-ion batteries mainly lies in the improvement of capacity and voltage. However, when the voltage window of the positive active material is fixed, the capacity that can be improved by adjusting the main component of the active material and element doping is limited. In view of this problem, at present, the voltage window of the positive active material is expanded to improve the charge and discharge capacity of the positive active material, and at the same time, increasing the proportion of active metals also plays an important role in improving the capacity of the positive active material. However, expanding the voltage window of the positive active material will induce its irreversible phase transition process at high potential, thereby damaging the structure and cycle stability of the positive active material; and when the capacity of the positive active material is improved by increasing the component of active metals, the variable valence of more active metals and the extraction of sodium ions will increase the structural stress of the positive active material, which is easy to cause the generation of crystal structure defects and the cracking of the material, which is not conducive to the long cycle stability of the positive active material. Therefore, it is expected to obtain a higher voltage window while considering the cycle stability of the positive active material, and to improve the energy density of the battery.

[0051] In view of the above problems, the present application provides a battery monomer, which comprises a positive electrode sheet, the positive electrode sheet comprises a current collector and a positive active material layer arranged on at least one side of the current collector, the positive active material layer comprises a positive active material, the positive active material comprises an O3 phase layered metal oxide, and the layered metal oxide comprises a Ti element; in the positive active material particles containing the layered metal oxide, the Ti element is distributed in the particle interior and the particle surface, and the distribution concentration of the Ti element in the particle interior is greater than that on the particle surface. In a sodium battery system, introducing the Ti element into the interior of the positive active material particles containing the O3 phase layered metal oxide can effectively improve the working voltage of the positive active material and the battery monomer, thereby improving the energy density of the battery monomer; and introducing the Ti element into the surface of the positive active material particles containing the O3 phase layered metal oxide can improve the surface stability of the positive active material and improve the cycle stability of the positive material. Therefore, the battery monomer can improve the voltage window of the positive active material and the battery monomer while considering the cycle stability of the positive active material, and improve the energy density of the battery monomer.

[0052] The battery monomer disclosed in the embodiments of the present application can be used in various energy storage systems using the battery monomer or the battery device including the battery monomer as a power source or using the battery monomer or the battery device including the battery monomer as an energy storage element. The power consumption equipment can include but is not limited to mobile phones, tablets, notebook computers, electric toys, electric tools, electric vehicles, electric vehicles, ships, spacecraft, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0053] The first aspect of the present application provides a battery monomer, which comprises a positive electrode sheet, the positive electrode sheet comprising a current collector and a positive electrode active material layer provided on at least one side of the current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising an O3 phase layered metal oxide, the layered metal oxide comprising a Ti element; in the positive electrode active material particles containing the layered metal oxide, the Ti element is distributed in the particle interior and the particle surface, and the distribution concentration of the Ti element in the particle interior is greater than that on the particle surface.

[0054] At present, in the sodium battery system, the introduction of Ti element in the positive electrode active material is mainly used to inhibit the structural change of the positive electrode active material at high voltage, and the change of the crystal structure stress caused by the deintercalation of sodium ions is relieved by using the flexible characteristics of TiO6 octahedron itself, thereby achieving the purpose of improving the cycle stability of the positive electrode active material at high voltage. However, too high Ti element doping amount will reduce the charge and discharge capacity of the positive electrode active material. In the present application, by controlling the different doping concentrations of Ti element in the particle phase and on the surface of the positive electrode active material, more Ti elements are distributed in the particle interior, which can effectively improve the discharge voltage of the O3 phase layered metal oxide, and less Ti elements are distributed on the particle surface, which can inhibit the generation of side reactions and microcracks on the particle surface of the positive electrode active material.

[0055] Transition metal ion Ti 4+The outer layer of the positive electrode active material particle has no 3d electron, which is easy to form a strong covalent bond with the O element. Introducing Ti element doping on the surface of the positive electrode active material particle can stabilize the O element on the surface of the positive electrode active material, weaken the oxidizability of the O element at high potential, inhibit the side reaction and the surface cracking and restructuring process of the positive electrode active material, and improve the cycle stability of the positive electrode active material. At the same time, the strong covalent Ti-O bond can easily enhance the ionicity of the bond between the metal ions around the Ti-O bond and oxygen, and the electron transfer of the active metal element is more likely to occur, which can reduce the Fermi level of the active metal element, improve the redox activity of the positive electrode active material in the limited voltage window, and further increase the activity of the variable valence transition metal element in the limited voltage window by introducing Ti element into the positive electrode active material particle, thereby effectively improving the working voltage of the positive electrode active material and the battery cell, and improving the charge-discharge specific capacity and energy density of the battery cell. The distribution concentration of the Ti element in the positive electrode active material particle is greater than the distribution concentration of the Ti element on the surface of the particle, which can improve the voltage window improvement effect of the Ti element on the positive electrode active material, and to a certain extent, solve the problem that the Ti element doping on the surface of the particle is easy to reduce the charge-discharge capacity of the positive electrode active material.

[0056] In the present application, introducing Ti element into the positive electrode active material particle can effectively improve the working voltage of the positive electrode active material and the battery cell, and further improve the energy density of the battery cell. Introducing Ti element on the surface of the positive electrode active material particle can improve the surface stability of the positive electrode active material and improve the cycle stability of the positive electrode active material. The distribution concentration of the Ti element in the positive electrode active material particle is greater than the distribution concentration of the Ti element on the surface of the particle, which is beneficial to further improve the charge-discharge specific capacity and energy density of the positive electrode active material and the battery cell.

[0057] Therefore, the battery cell of the first aspect of the present application has at least the following beneficial effects: the voltage window of the positive electrode active material and the battery cell can be improved on the basis of considering the cycle stability of the positive electrode active material, and the energy density of the battery cell can be improved.

[0058] In some embodiments of the present application, the particle surface in the positive electrode active material particle can be defined as the region extending from the outermost surface of the positive electrode active material particle to the particle center by a distance ≤ H, and the particle interior can be defined as the region extending from the outermost surface of the positive electrode active material particle to the particle center by a distance > H. Optionally, H can be any value greater than or equal to 0. For example, in a single positive electrode active material particle, the particle surface can be defined as the region extending from the outermost surface of the positive electrode active material particle to the particle center by a distance ≤ 0.5% of the particle size, and the particle interior can be defined as the region extending from the outermost surface of the positive electrode active material particle to the particle center by a distance > 0.5% of the particle size. Alternatively, the particle surface can be defined as the region extending from the outermost surface of the positive electrode active material particle to the particle center by a distance ≤ 200 nm, and the particle interior can be defined as the region extending from the outermost surface of the positive electrode active material particle to the particle center by a distance > 200 nm.

[0059] In some embodiments of the present application, X-ray diffraction (XRD) analysis can be used to determine whether the O3 phase layered metal oxide exists in the positive electrode active material; EDS energy spectrum analysis, electron probe microanalysis (EPMA), or inductively coupled plasma emission spectrometry (ICP) can be used to qualitatively and quantitatively analyze the element composition in the positive electrode active material; in addition, the distribution of Ti in the positive electrode active material particle can be characterized by energy spectrum analysis or electron probe technology. For example, after ion polishing section of the positive electrode sheet, the positive electrode active material particle containing the layered metal oxide can be determined by electron probe microanalysis (EPMA) and EDS energy spectrum analysis. A fine focused electron beam of 5 kV to 50 kV is generated by an electron gun to bombard the sample surface, knock out the inner shell electrons of the surface composition elements, and ionize them. At this time, the outer shell electrons quickly fill the vacancies and release energy, generating characteristic X-rays. The wavelength and intensity of the characteristic X-rays are measured by an X-ray energy spectrometer (EDS), thereby qualitatively or quantitatively analyzing the elements contained in the micro area, obtaining the distribution area and concentration change of Ti in the positive electrode active material particle. In addition, it can be understood that the distribution concentration in the present application can be understood as the volume distribution concentration, or the mass distribution concentration.

[0060] In some embodiments of the present application, in the layered metal oxide of the O3 phase, the metal elements include transition metal elements, which can be mainly Ni, Mn and Fe, and include one or more of Zn, Ti and Cu. For example, in the layered metal oxide, the sum of the molar contents of Ni, Mn and Fe can be greater than the sum of the molar contents of Zn, Ti and Cu. In a sodium battery system, the specific capacity of the O3 phase layered metal oxide containing nickel-iron-manganese elements is relatively high, on this basis, the introduction of Zn element can promote the redox process of Ni element, further improve the capacity of the positive active material, and the introduction of copper element can improve the structural stability of the positive active material at high potential. Thus, the voltage window of the positive active material and the battery cell can be further improved on the basis of considering the cycle stability of the positive active material, and the energy density of the battery cell can be improved.

[0061] In some embodiments of the present application, the layered metal oxide can include Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f , wherein 0.8≤x<1.1; 0

[0062] For example, the value of x can be 0.8, 0.85, 0.9, 0.95, 1, 1.05 or 1.1, etc.

[0063] For example, the value of y can be 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, etc.

[0064] For example, the value of z can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4, etc.

[0065] For example, the value of a can be 0.05, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22 or 0.25, etc.

[0066] Exemplarily, the value of b can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5, etc.

[0067] Exemplarily, the value of c can be 0.05, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28 or 0.3, etc.

[0068] Exemplarily, the value of d can be 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, etc.

[0069] Exemplarily, the value of e can be 0, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, etc.

[0070] Exemplarily, the value of f can be 0, 0.005, 0.01, 0.02, 0.03, 0.04 or 0.05, etc.

[0071] The element composition of Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f can be qualitatively and quantitatively analyzed by ICP testing and electron microscope EDS analysis. The sodium ion content in Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f is relatively high, and its phase state is O3 phase. On this basis, Zn element, Ti element and Cu element are introduced, and the content of each element is controlled to meet the given range, which is conducive to further considering the cycle stability and high voltage window of the positive active material, and improving the energy density of the battery monomer. It can be understood that the sodium ion content in Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±fThe positive electrode active material can include the doping element M or can not include the doping element M. The doping element M can be introduced to further improve the cycle performance of the battery cell.

[0072] In some embodiments of the present application, the layered metal oxide Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f In the positive electrode active material, the value of a can be in the range of 0.05≤a<0.15. For example, the value of a can be 0.05, 0.08, 0.1, 0.12, or 0.15, etc. Controlling the content of Ti element to be in the given range is beneficial to improve the discharge voltage of the positive electrode active material and the battery cell, and also reduces the risk of the decrease of the charge-discharge capacity and the cycle stability of the positive electrode active material and the battery cell due to the increase of the doping amount of Ti element, thereby further taking into account the cycle stability and high voltage window of the positive electrode active material, and improving the energy density of the battery cell.

[0073] In some embodiments of the present application, the layered metal oxide Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f In the positive electrode active material, the value of y can be in the range of 0.03≤y≤0.08. For example, the value of y can be 0.03, 0.04, 0.05, 0.06, 0.07, or 0.08, etc. Thereby, the cycle stability and high voltage window of the positive electrode active material can be further taken into account, and the energy density of the battery cell can be improved.

[0074] In some embodiments of the present application, the layered metal oxide Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f In the positive electrode active material, the value of d can be in the range of 0.02≤d≤0.05. For example, the value of d can be 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05, etc. Thereby, the cycle stability and high voltage window of the positive electrode active material can be further taken into account, and the energy density of the battery cell can be improved.

[0075] In some embodiments of the present application, the layered metal oxide Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f In some embodiments of the present application, the values of a, y and d can satisfy 0.1≤a+y+d≤0.25. For example, the values of a, y and d can be 0.1, 0.12, 0.15, 0.18, 0.2, 0.22 or 0.25, etc. In this way, the cycle stability and high voltage window of the positive active material can be further considered, and the energy density of the battery cell can be improved.

[0076] In some embodiments of the present application, in the positive active material particle containing the layered metal oxide, the distribution concentration of the Ti element can show a decreasing trend in the direction from the inside to the outside of the particle. For example, in the positive active material particle containing the layered metal oxide, the distribution concentration of the Ti element can gradually decrease in the direction from the inside to the outside of the particle; or the positive active material particle containing the layered metal oxide can include a multi-layer structure arranged in layers from the inside to the outside, and the distribution concentration of the Ti element can decrease layer by layer in the direction from the inside to the outside of the particle. For example, taking the structure that the positive active material particle includes an inner core and an outer shell layer as an example, the inner core can include Na x1 Zn y1 Ni z1 Ti a1 Mn b1 Fe c1 Cu d1 M1 e1 O 2±f1 , wherein 0.8≤x1<1.1; 0 x2 Zn y2 Ni z2 Ti a2 Mn b2 Fe c2 Cu d2 M2 e2 O 2±f2wherein, 0.8≤x2<1.1; 0

[0077] In some embodiments of the present application, the Dv50 particle size of the positive electrode active material can be 6 μm to 10 μm, for example, can be 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm, etc. Wherein, the Dv50 particle size refers to the particle size corresponding to the cumulative volume distribution percentage of 50%. The Dv50 particle size of the positive electrode active material can be determined by referring to the standard GB / T 19077-2016 / ISO 13320:2009, using a laser particle size analyzer (Malvern Master Size 2000). The specific test process can include: taking an appropriate amount of sample to be tested (the sample concentration ensures that the light density is 8%-12%), adding 20 ml of deionized water, and simultaneously ultrasonicating for 5 min (53 KHz / 120 W) to ensure that the sample is completely dispersed, and then determining the sample according to the standard GB / T 19077-2016 / ISO 13320:2009. Thus, the positive electrode active material has a suitable compaction density and specific surface area, which is further beneficial to further make the battery cell have a higher energy density and better cycle performance.

[0078] In some embodiments of the present application, the compaction density of the positive electrode active material under a pressure of 3 tons can be 3.0 g / cm 3 ~ 3.15 g / cm 3 , for example, can be 3.0 g / cm 3 , 3.02 g / cm 3 , 3.05 g / cm 3 , 3.08 g / cm 3 , 3.1 g / cm 3 , 3.12 g / cm 3 or 3.15 g / cm 3, etc. Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density, and thus it is beneficial to further improve the energy density of the battery cell.

[0079] In some embodiments of the present application, the voltage window of the battery cell can be 1.5 V to 4.15 V, and the upper limit of the working voltage of the battery cell can be 3.95 V to 4.15 V. For example, the voltage window of the battery cell can be 1.5 V to 4.15 V, 1.5 V to 4.1 V, 1.5 V to 4.05 V, 1.5 V to 4 V, or 1.5 V to 3.95 V, etc. The voltage window of the battery cell will change slightly depending on the specific type and element composition of the positive electrode active material, and the voltage window of the battery cell can be determined by analyzing its cyclic voltammetry curve (CV curve).

[0080] In some embodiments of the present application, in the positive electrode tab, the positive electrode current collector can use a conventional metal foil or a composite current collector (a metal material can be arranged on a polymer substrate to form a composite current collector). For example, the positive electrode current collector can include at least one of a copper foil, an aluminum foil, a nickel foil, a stainless steel foil, a stainless steel mesh, and a carbon-coated aluminum foil.

[0081] In some embodiments of the present application, in the positive electrode tab, the positive electrode active material layer can also optionally include at least one of a binder, a conductive agent, and other optional additives. Among them, the binder, conductive agent, and additive can all be conventional choices in the art, for example, the conductive agent can include but is not limited to one or more of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, and the binder can include but is not limited to one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). These materials can all be obtained through commercial channels.

[0082] In some embodiments of the present application, the battery cell can refer to a battery that can be activated by charging after discharging to continue to use the active material.

[0083] It can be understood that the battery cell proposed in the present application can be a sodium ion battery.

[0084] Generally, a battery cell includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging of the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet and serves to separate them. The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet.

[0085] [negative electrode sheet]

[0086] In the battery, the negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material. The negative electrode current collector can be a conventional metal foil or a composite current collector (e.g., a metal material can be disposed on a polymer substrate to form a composite current collector). As an example, the negative electrode current collector can be a copper foil. The negative electrode active material layer can also optionally include a binder and a conductive agent. The conductive agent is used to improve the electrical conductivity of the negative electrode active material layer, and the binder is used to firmly bond the negative electrode active material and the binder to the negative electrode current collector. The present application does not make specific limitations on the types of conductive agents and binders of the negative electrode sheet, which can be selected according to actual needs. As an example, the conductive agent can include, but is not limited to, at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. As an example, the binder can include, but is not limited to, at least one of styrene butadiene rubber (SBR), styrene-butadiene rubber (SBCs), water-based acrylic resin, and carboxymethyl cellulose (CMC).

[0087] The negative electrode active material layer can also optionally include a thickening agent, such as carboxymethyl cellulose (CMC), etc. However, the present application is not limited thereto, and other materials that can be used as a thickening agent for a sodium-ion battery negative electrode sheet can also be used.

[0088] In some embodiments of the present application, the battery cell of the first aspect of the present application can be a sodium metal battery, in which case the negative electrode active material can include, but is not limited to, metallic sodium. For example, the negative electrode active material can also be an alloy of metallic sodium and other various metal or non-metal elements.

[0089] In some embodiments of the present application, the battery cell of the first aspect of the present application can also be a negative electrode-free sodium metal battery. In this case, the negative electrode is only composed of a metal foil current collector, without sodium metal on its surface. During the cycle, only sodium in the positive electrode is used, and sodium metal is precipitated and peeled off on the negative electrode side.

[0090] [electrolyte]

[0091] The electrolyte can include an electrolyte salt and a solvent.

[0092] As an example, the electrolyte salt can include, but is not limited to, at least one of sodium hexafluorophosphate, sodium difluoro oxalate borate, sodium tetrafluoroborate, sodium bisoxalate borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate, and sodium bis(trifluoromethylsulfonyl)imide.

[0093] As an example, the solvent can include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0094] In some embodiments, an additive can also be included in the electrolyte. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive capable of improving certain properties of the battery, such as an additive for improving overcharge performance, an additive for improving high-temperature performance, and an additive for improving low-temperature performance.

[0095] [Separator]

[0096] As the separator described above, the present application is not particularly limited, and any known porous structure separator having electrochemical stability and mechanical stability can be used according to the actual needs, for example, can include, but is not limited to, a single layer or a multi-layer film including at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0097] The shape of the battery cell is not particularly limited in the embodiments of the present application, and can be cylindrical, square, or any other shape. As an example, FIG. 1 is a battery cell 1 having a square structure.

[0098] In some embodiments of the present application, the battery cell can include an outer package. The outer package is used to package the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0099] In some embodiments, the outer package can include a housing and a cover plate. The housing can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The housing has an opening communicating with the receiving cavity, and the cover plate can be provided on the opening to close the receiving cavity.

[0100] The positive electrode sheet, the negative electrode sheet and the separator film can form an electrode assembly through a winding process or a stacking process. The electrode assembly is packaged in the accommodation cavity. The number of electrode assemblies contained in the battery cell can include one or several, which can be adjusted according to requirements.

[0101] In some embodiments, the outer package of the battery cell can include a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell. The outer package of the battery can also include a soft package, such as a pouch soft package. The material of the soft package can be plastic, which can include at least one of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS).

[0102] Based on the same inventive concept, the second aspect of the present application provides a positive electrode active material, comprising: a layered metal oxide of O3 phase, the layered metal oxide comprising a Ti element; in the positive electrode active material particle containing the layered metal oxide, the Ti element is distributed in the particle interior and the particle surface, and the distribution concentration of the Ti element in the particle interior is greater than that on the particle surface. In this way, better cycle stability and high voltage window can be considered, and the energy density of the battery cell can be improved.

[0103] In some embodiments of the present application, the layered metal oxide can include Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f , wherein 0.8≤x<1.1; 0

[0104] In some embodiments of the present application, the layered metal oxide Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f At least one of the following four conditions can be met: 0.05≤a≤0.15, 0.03≤y≤0.08, 0.02≤d≤0.05, 0.1≤a+y+d≤0.25.

[0105] In the positive electrode active material, the optional types of the layered metal oxide (including the optional general formula and the optional ranges of the components and the subscript value ranges, etc.), the concentration distribution change of the Ti element in the positive electrode active material particles, the Dv50 particle size of the positive electrode active material, and the compaction density of the positive electrode active material under a pressure of 3 tons have been described in detail in the foregoing part, and will not be repeated here.

[0106] Based on the same inventive concept, the third aspect of the present application provides a method for preparing a positive electrode active material, comprising: preparing precursor particles containing metal elements; mixing the precursor particles with a sodium source, a metal source, and performing a first calcination treatment, wherein: the metal elements include a Ti element, and the metal source includes a Ti source; in the precursor particles, the mole percentage of the Ti element in the total mole amount of the metal elements is n1; in the metal source, the mole percentage of the Ti element in the total mole amount of the metal elements is n2, n2 < n1. In this way, positive electrode active material particles with a distribution concentration of the Ti element inside the particles greater than the distribution concentration of the Ti element on the surface of the particles can be obtained, and the cycle stability and high voltage window of the positive electrode active material can be considered at the same time, and the energy density of the battery cell can be improved.

[0107] In some embodiments of the present application, the metal elements can include Ni elements, Mn elements, Fe elements, Zn elements, Ti elements, and Cu elements; the metal source can include nickel sources, manganese sources, iron sources, zinc sources, titanium sources, and copper sources; in the precursor particles, the mole percentage of the Ti element in the total mole amount of the Ni elements, Mn elements, Fe elements, Zn elements, Ti elements, and Cu elements is n1; in the metal source, the mole percentage of the Ti element in the total mole amount of the Ni elements, Mn elements, Fe elements, Zn elements, Ti elements, and Cu elements is n2, n2 < n1. In this way, the cycle stability and high voltage window of the positive electrode active material can be further considered at the same time, and the energy density of the battery cell can be improved.

[0108] In some embodiments of the present application, mixing the precursor particles with the sodium source, the nickel source, the manganese source, the iron source, the zinc source, the titanium source, and the copper source and performing the first calcination treatment can directly prepare the O3 phase layered metal oxide by adjusting the conditions such as the temperature, atmosphere, and time of the first calcination treatment.

[0109] In some embodiments of the present application, after mixing the precursor particles with the sodium source, the nickel source, the manganese source, the iron source, the zinc source, the titanium source, and the copper source and performing the first calcination treatment, a second calcination treatment can also be performed on the first calcination product, and the temperature of the second calcination treatment can be greater than the temperature of the first calcination treatment. In this way, the raw material components can be first converted into the layered metal oxide, and then the phase state of the layered metal oxide can be converted to the O3 phase through the second calcination, so as to obtain the O3 phase layered metal oxide.

[0110] In some embodiments of the present application, the first calcination process can have a temperature of 650 °C to 950 °C and a time of 5 h to 20 h. For example, the first calcination process can have a temperature of 650 °C, 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, or 950 °C, etc. The first calcination process can have a time of 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, or 20 h, etc. In this way, the precursor particles and the metal sources can be promoted to transform into the layered metal oxide. Optionally, the first calcination process can be performed in an oxygen-containing atmosphere and / or an inert gas atmosphere. The oxygen-containing atmosphere can include, but is not limited to, an air atmosphere, an oxygen atmosphere, or an atmosphere in which oxygen is mixed with other gases such as argon. The inert gas atmosphere can include, but is not limited to, an argon atmosphere. For example, the first calcination process can be performed in an air atmosphere or an oxygen atmosphere.

[0111] In some embodiments of the present application, the second calcination process can have a temperature of 700 °C to 1000 °C and a time of 5 h to 20 h. For example, the second calcination process can have a temperature of 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, 950 °C, or 1000 °C, etc. The second calcination process can have a time of 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, or 20 h, etc. By having the temperature of the second calcination process greater than the temperature of the first calcination process and satisfying the above conditions, the layered metal oxide obtained from the first calcination process can be promoted to transform into the O3 phase. Optionally, the time of the second calcination process can be greater than the time of the first calcination process. Further optionally, the second calcination process can be performed in an oxygen-containing atmosphere and / or an inert gas atmosphere. The oxygen-containing atmosphere can include, but is not limited to, an air atmosphere, an oxygen atmosphere, or an atmosphere in which oxygen is mixed with other gases such as argon. The inert gas atmosphere can include, but is not limited to, an argon atmosphere. For example, the second calcination process can be performed in an air atmosphere or an oxygen atmosphere.

[0112] In some embodiments of the present application, the precursor particles can further include an M element. The M element can include one or more of Li, Mg, Ca, Zr, Co, Al. Optionally, the precursor particles can be mixed with a sodium source, a nickel source, a manganese source, an iron source, a zinc source, a titanium source, a copper source, and an M source and subjected to the first calcination process. In this way, a positive electrode active material having an M element doped therein can be prepared.

[0113] In some embodiments of the present application, the precursor particles can be prepared by co-precipitation or mechanical ball milling. For example, in the case of co-precipitation, water-soluble sources of nickel, manganese, iron, zinc, titanium and copper can be mixed with water, and the pH value of the mixture is adjusted to prepare precursor particles containing Ni, Mn, Fe, Zn, Ti and Cu elements. Optionally, if M element doping is needed in the precursor particles, the mixture can further include the addition of a water-soluble source of M. For another example, in the case of mechanical ball milling, oxides of Ni, Mn, Fe, Zn, Ti and Cu can be mixed and subjected to mechanical ball milling to obtain precursor particles containing Ni, Mn, Fe, Zn, Ti and Cu elements. Optionally, if M element doping is needed in the precursor particles, the mixture can further include the addition of an oxide of M. Further optionally, when the precursor particles are prepared by mechanical ball milling, the mixture can be subjected to high-speed mixing by a mixer, such as a mixer with an inclined mixing blade. The rotation speed of the mechanical ball milling can be 10-100 rpm, and the mixing time can be 1-10 h. Further optionally, the rotation speed of the mechanical ball milling can be 40-60 rpm.

[0114] In some embodiments of the present application, the Ti element can be uniformly distributed in the precursor particles. In this case, positive electrode active material particles having a core and a shell layer structure can be prepared, the shell layer is coated on at least part of the surface of the core, and the distribution concentration of the Ti element in the shell layer is less than that in the core, and the distribution concentration of the Ti element inside the positive electrode active material particles is greater than that on the surface of the positive electrode active material particles.

[0115] In some embodiments of the present application, in the direction from the inside to the outside of the precursor particles, the distribution concentration of the Ti element can show a decreasing trend, such as gradually decreasing, or decreasing layer by layer. Optionally, the precursor particles can be prepared by co-precipitation, for example, water-soluble sources of nickel, manganese, iron, zinc, titanium and copper can be mixed with water, and the pH value of the mixture is adjusted for co-precipitation reaction. In terms of the total moles of Ni, Mn, Fe, Zn, Ti and Cu elements, the mole percentage of Ti element in the co-precipitation reaction system can be gradually reduced or periodically reduced, such as every 2 h or 3 h. It can be understood that when the precursor particles are doped with M element, the mole percentage of Ti element in the co-precipitation reaction system can be controlled in terms of the total moles of Ni, Mn, Fe, Zn, Ti, Cu and M elements.

[0116] In some embodiments of the present application, the Dv50 particle size of the prepared positive electrode active material can be adjusted by adjusting the particle size distribution of the precursor particles and / or the conditions of the first calcination process.

[0117] In some embodiments of the present application, the sodium source, the nickel source, the manganese source, the iron source, the zinc source, the titanium source, and the copper source can each independently be one or more of a metal, a carbonate, a bicarbonate, an oxalate, an acetate, a metal oxide, a metal hydroxide, a halide, a nitrate, and a sulfate.

[0118] It should be noted that the positive electrode active material of the second aspect of the present application, the method for preparing the positive electrode active material of the third aspect of the present application, and the battery cell of the first aspect of the present application are based on the same inventive concept, and the features and effects described for the positive electrode active material in the battery cell of the first aspect of the present application are also applicable to the positive electrode active material of the second aspect of the present application and the method for preparing the positive electrode active material of the third aspect of the present application, which will not be repeated here.

[0119] The fourth aspect of the present application provides a positive electrode tab, which comprises the positive electrode active material of the second aspect of the present application or the positive electrode active material prepared by the method of the third aspect of the present application. It can be understood that the features and effects described for the positive electrode tab in the battery cell of the first aspect of the present application, the positive electrode active material of the second aspect of the present application, and the method for preparing the positive electrode active material of the third aspect of the present application are also applicable to the positive electrode tab of the fourth aspect of the present application, which will not be repeated here.

[0120] Based on the same inventive concept, the fifth aspect of the present application provides a method for preparing a battery cell, which comprises: mixing a positive electrode active material, a conductive agent, and a binder with a solvent to obtain a positive electrode slurry; coating the positive electrode slurry on at least one side of a current collector to obtain a positive electrode tab, wherein the positive electrode active material comprises a layered metal oxide in an O3 phase, and the layered metal oxide comprises a Ti element; and in the positive electrode active material particles containing the layered metal oxide, the distribution concentration of the Ti element inside the particles is greater than the distribution concentration of the Ti element on the surface of the particles. The method for preparing a battery cell of the fifth aspect of the present application is based on the same inventive concept as the battery cell of the first aspect of the present application, and the features and effects described for the battery cell of the first aspect of the present application are also applicable to the method for preparing a battery cell of the second aspect of the present application, which will not be repeated here. In general, the battery cell prepared by the method can improve the voltage window of the positive electrode active material and the battery cell and improve the energy density of the battery cell while taking into account the cycle stability of the positive electrode active material.

[0121] In some embodiments of the present application, the layered metal oxide can comprise Na x Zn y Niz Ti a Mn b Fe c Cu d M e O 2±f wherein, 0.8≤x<1.1; 0

[0122] The sixth aspect of the present application provides a battery device, which comprises the battery cell of the first aspect of the present application, or the positive electrode active material of the second aspect of the present application, or the positive electrode active material prepared by the method of the third aspect of the present application, or the positive electrode plate of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application. In some embodiments, the battery device can be a battery cell, or a battery module or a battery pack assembled by the battery cell. The number of battery cells contained in the battery module or the battery pack can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module or the battery pack.

[0123] FIG. 2 is a battery module 2 as an example. Referring to FIG. 2, in the battery module 2, a plurality of battery cells 1 can be arranged in sequence along the length direction of the battery module 2. Of course, they can also be arranged in other arbitrary ways. Further, the plurality of battery cells 1 can be fixed by fasteners. The battery module 2 can also include a housing having an accommodation space, and the plurality of battery cells 1 are accommodated in the accommodation space. In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0124] In some embodiments, the battery pack can include an accommodation space, and the plurality of battery cells can be directly accommodated in the accommodation space of the battery pack. Alternatively, the plurality of battery cells can be assembled into one or more battery modules first, and then the battery modules are accommodated in the accommodation space of the battery pack.

[0125] Figs. 3 and 4 are a battery pack 3 as an example. Referring to Figs. 3 and 4, the battery pack 3 can include a battery case and a plurality of battery modules 2 disposed in the battery case, the battery module 2 including a plurality of battery cells 1. The battery case includes an upper case 4 and a lower case 5, the upper case 4 being capable of being provided on the lower case 5 and forming an enclosed space for accommodating the battery modules 2. The plurality of battery modules 2 can be arranged in the battery case in any manner.

[0126] A seventh aspect of the present application provides a power consuming device, which includes the battery cell of the first aspect of the present application, or the electrode tab of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application, or the battery device of the sixth aspect of the present application.

[0127] Specifically, the battery cell or the battery device can serve as a power source of the power consuming device, or can serve as an energy storage unit of the power consuming device. The power consuming device can include, but is not limited to, a mobile device (e.g., a mobile phone, a notebook computer), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck), an electric train, a ship and a satellite, an energy storage system.

[0128] Fig. 5 is a power consuming device as an example. The power consuming device includes a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. The power consuming device as another example can include a mobile phone, a tablet computer, a notebook computer. The power consuming device generally requires thinning, and the battery cell can be used as a power source.

[0129] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are intended to explain the present application only, and should not be understood as limiting the present application. In the embodiments, specific techniques or conditions not mentioned are performed according to the techniques or conditions described in the literature in the art or according to the product manual. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained commercially.

[0130] Example 1

[0131] (1) Positive active material

[0132] a) Put nickel oxide, manganese oxide, iron oxide, zinc oxide, copper oxide, and titanium dioxide into a mixer for mechanical ball milling at a speed of 40 rpm to 60 rpm for 4 h to obtain precursor particles, wherein, in the precursor particles, the mole fraction of titanium is n1 based on the total moles of nickel, manganese, iron, zinc, copper, and titanium;

[0133] b) the obtained precursor particles are mixed with sodium carbonate, nickel oxide, manganese oxide, iron oxide, zinc oxide, copper oxide, titanium dioxide in a mixer for mechanical ball milling, wherein the ball milling speed and the ball milling time are the same as in step a); the obtained mixture is calcined at 800 DEG C in air for 10 h, wherein the molar ratio of titanium in the total molar amount of nickel, manganese, iron, zinc, copper and titanium in the nickel oxide, manganese oxide, iron oxide, zinc oxide, copper oxide and titanium dioxide added in step b) is n2, n2 < n1;

[0134] c) the calcined product obtained in step b) is sieved and secondarily calcined at 900 DEG C in air for 15 h to obtain the O3 phase positive electrode active material.

[0135] (2) Preparation of the positive electrode sheet: the prepared positive electrode active material, nanoscale conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) are mixed uniformly in a mass ratio of 94:3:3 with solvent NMP, and then coated on both sides of an aluminum foil with a thickness of 13 μm, dried and cold-pressed to obtain the positive electrode sheet, the coating surface density of the positive electrode sheet being 0.02 g / cm 2 .

[0136] (3) Preparation of the negative electrode sheet: the negative electrode active material hard carbon, nanoscale conductive agent acetylene black, binder styrene butadiene rubber (SBR) and thickening agent sodium carboxymethyl cellulose (CMC) are mixed uniformly in a weight ratio of 95:2:2:1 in a deionized water solvent system, and then coated on both sides of a copper foil with a thickness of 6 μm, dried and cold-pressed to obtain the negative electrode sheet, the coating surface density of the negative electrode sheet being 0.012 g / cm 2 .

[0137] (4) Electrolyte: equal volumes of ethylene carbonate (EC), diethyl carbonate (DEC) and propylene carbonate (PC) are mixed to obtain an organic solvent, and NaPF6 is dissolved in the organic solvent to prepare an electrolyte with a NaPF6 concentration of 1 mol / L.

[0138] (5) Separating membrane: a porous polyethylene membrane with a thickness of 12 μm.

[0139] (6) Preparation of the battery

[0140] The above positive electrode sheet, separating membrane and negative electrode sheet are stacked in order, with the separating membrane between the positive electrode sheet and the negative electrode sheet to play a separating role, and the prepared electrolyte is added, so that the preparation of the battery is completed.

[0141] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. This stacking process yields a bare cell. The bare cell is then placed in outer packaging, infused with the prepared electrolyte, and sealed to obtain a full battery.

[0142] Examples 2-9 and Comparative Examples 1-7

[0143] The difference between Examples 2-9 and Comparative Examples 1-7 and Example 1 lies in the different raw material ratios in steps a) and b) during the preparation process. Consequently, the elemental composition of the resulting precursor particles, positive electrode active materials, and related test results are also different, as detailed in Tables 1 and 2. In Examples 5-7, the dopant element M is Ca, provided in the form of CaO during the preparation of the precursor particles and the first calcination product.

[0144] (7) Test

[0145] i) XRD testing: Using CuKα rays as the radiation source, the ray wavelength... The scanning angle range was 10° to 60°, and the scanning rate was 2° / min. Based on the characteristic peaks of the obtained XRD pattern and in conjunction with standard cards, it was determined whether the prepared positive electrode active material contained layered metal oxides of the O3 phase.

[0146] ii) ICP test: Referring to EPA6010D-2014 "Inductively Coupled Plasma Atomic Emission Spectrometry", the prepared positive electrode active material sample is chemically treated and digested into a solution, then atomized into plasma to be excited to emit characteristic spectral lines of elements. The elemental composition in the prepared positive electrode active material is qualitatively or quantitatively analyzed based on the wavelength and intensity of the spectral lines (which are proportional to the concentration).

[0147] iii) EDS energy dispersive spectroscopy analysis: After ion polishing the cross section of the sample to be tested, the distribution area and concentration change of Ti element in the cross section of the positive electrode active material particles are characterized.

[0148] iv) Electrochemical performance testing:

[0149] Under constant temperature of 25℃, the cathode material is charged at 0.1C to 4.0V at a voltage of 1.5V to 4.0V, then charged at a constant voltage of 4.0V until the current is ≤0.05C. After standing for 5 minutes, it is discharged at 0.1C to 1.5V. The discharge specific capacity is recorded as D0 (unit: mAh / g), and the specific energy is recorded as E0 (unit: Wh / g). The discharge voltage V0 = E0 / D0 (unit: V) is recorded, and the specific capacity of the positive electrode active material is calculated. The above process is repeated, and the discharge voltage V0 after n cycles is recorded. n =E n / D n (Unit: V), record the discharge specific capacity D of each battery cell after 100 cycles.100 , the cycle capacity retention rate of 100 cycles is obtained, i.e. D 100 / D0x100%.

[0150] The above-mentioned related tests were carried out on Examples 1-9 and Comparative Examples 1-7, and the test results are shown in Table 1, Table 2 and Figure 6.

[0151] Table 1 Partial differences of Examples 1-9 and Comparative Examples 1-7

[0152] Table 2 Other differences and test results of Examples 1 and Comparative Examples 1-7

[0153] Results and conclusions:

[0154] In combination with Examples 1-9, Comparative Examples 1-7 and Table 1, in the sodium battery system, the Ti element is introduced into the interior and surface of the O3 phase layered metal oxide positive electrode active material particles, and the distribution concentration of the Ti element in the interior of the particles is greater than that on the surface of the particles, which can improve the specific capacity of the positive electrode active material and the discharge median voltage of the battery monomer, so that the battery monomer has high energy density and cycle performance. In combination with Example 1 and Comparative Examples 1-3, it can be seen that the introduction of titanium element, iron element and copper element into the O3 phase positive electrode active material particles containing nickel, iron and manganese elements is beneficial to further obtain high energy density and cycle performance. In combination with Examples 1 to 4, it can be seen that controlling the appropriate content of Ti element is beneficial to make the positive electrode active material have high discharge specific capacity, and the battery monomer has high discharge median voltage and good cycle performance. In combination with Examples 1 and Examples 5-7, it can be seen that other doping elements (such as Ca element) can also be introduced into the O3 phase layered metal oxide positive electrode active material to further improve the cycle performance of the battery monomer.

[0155] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, wherein, The positive electrode tab comprises a current collector and a positive electrode active material layer provided on at least one side of the current collector, and the positive electrode active material layer comprises a positive electrode active material, The positive electrode active material comprises an O3 phase layered metal oxide comprising a Ti element; in the positive electrode active material particles containing the layered metal oxide, the Ti element is distributed in the particle interior and the particle surface, and the distribution concentration of the Ti element in the particle interior is greater than that on the particle surface. 0.1≤a+y+d≤0.

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2. The battery cell of claim 1, wherein, The layered metal oxide comprises Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f wherein 0.8≤x<1.1; 0 y+z+a+b+c+d+e=1; 0 M comprises one or more of the following elements: Li, Mg, Ca, Zr, Co, Al.

3. The battery cell of claim 2, wherein, 0.05≤a≤0.15。 4. The battery cell of claim 2 or 3, wherein, 0.03≤y≤0.08。 5. The battery cell of any one of claims 2-4, wherein, 0.02≤d≤0.05。 6. The battery cell of any one of claims 2-5, wherein, In the positive electrode active material particles containing the layered metal oxide, in the direction from the inside to the outside of the particles, the distribution concentration of the Ti element shows a decreasing trend.

7. The battery cell according to any one of claims 1 to 6, wherein, The Dv50 particle size of the positive electrode active material is 6-10 μm.

8. The battery cell of any one of claims 1-7, wherein, The voltage window of the battery cell is 1.5-4.15 V, and the upper limit of the voltage window is 3.95-4.15 V.

9. The battery cell of any one of claims 1-8, wherein, The positive electrode active material has a compaction density of 3.0 g / cm 3 ~ 3.15 g / cm 3 .

10. The battery cell of any one of claims 1-9, wherein, The positive electrode active material comprises an O3 phase layered metal oxide comprising a Ti element; in the positive electrode active material particles containing the layered metal oxide, the Ti element is distributed in the particle interior and the particle surface, and the distribution concentration of the Ti element in the particle interior is greater than that on the particle surface.

11. A positive electrode active material, wherein, At least one of the following conditions is met: 0.05≤a≤0.15, 0.03≤y≤0.08, 0.02≤d≤0.05, 0.1≤a+y+d≤0.

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12. The positive electrode active material according to claim 11, wherein The layered metal oxide includes Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f wherein 0.8≤x<1.1; 0 y+z+a+b+c+d+e=1; 0 M includes one or more of Li, Mg, Ca, Zr, Co, Al.

13. The positive electrode active material according to claim 11 or 12, wherein The method comprises the steps of:

14. A method for producing a positive electrode active material, wherein, Preparation of precursor particles containing metal elements; Mixing the precursor particles with a sodium source and a metal source and performing a first calcination treatment, The metal elements include a Ti element, and the metal source includes a Ti source; In the precursor particles, the mole fraction of the Ti element in the total mole amount of the metal elements is n1; in the metal source, the mole fraction of the Ti element in the total mole amount of the metal elements is n2, and n2 The metal elements include a Ni element, a Mn element, a Fe element, a Zn element, a Ti element and a Cu element; the metal source includes a nickel source, a manganese source, an iron source, a zinc source, a titanium source and a copper source; in the precursor particles, the mole fraction of the Ti element in the total mole amount of the Ni element, the Mn element, the Fe element, the Zn element, the Ti element and the Cu element is n1; in the metal source, the mole fraction of the Ti element in the total mole amount of the Ni element, the Mn element, the Fe element, the Zn element, the Ti element and the Cu element is n2, and n2 15. The method of claim 14, wherein, Further comprising:

16. The method of claim 14 or 15, wherein, Performing a second calcination treatment on the first calcination product, and the temperature of the second calcination treatment is greater than that of the first calcination treatment. The temperature of the first calcination treatment is 650-950 °C, and the time is 5-20 h; and / or, 17. The method of claim 16, wherein, The temperature of the second calcination treatment is 700-1000 °C, and the time is 5-20 h. The precursor particles are prepared by a coprecipitation method or a mechanical ball milling method; and / or, 18. The method of any one of claims 14-17, wherein, In the direction from the inside to the outside of the precursor particles, the distribution concentration of the Ti element shows a decreasing trend. The method comprises the steps of:

19. A positive electrode sheet, wherein, ​ The positive electrode active material according to any one of claims 11 to 13, or the positive electrode active material prepared by the method according to any one of claims 14 to 18.

20. A method of making a battery cell, wherein, Comprising: mixing the positive electrode active material, the conductive agent, and the binder with a solvent to obtain a positive electrode slurry; coating the positive electrode slurry on at least one side of the current collector to obtain a positive electrode sheet, wherein the positive electrode active material comprises a layered metal oxide of O3 phase, the layered metal oxide comprising a Ti element; in the positive electrode active material particles containing the layered metal oxide, the distribution concentration of the Ti element inside the particles is greater than the distribution concentration of the Ti element on the surface of the particles.

21. The method of claim 20, wherein, The layered metal oxide comprises Na x Zn y Ni z Ti a Mn b Fe c Cu d M e O 2±f wherein 0.8≤x<1.1; 0 y+z+a+b+c+d+e=1; 0 M comprises one or more of the following elements: Li, Mg, Ca, Zr, Co, Al.

22. A battery device, wherein, Comprising: The battery cell according to any one of claims 1 to 10, or the positive electrode active material according to any one of claims 11 to 13, or the positive electrode active material prepared by the method according to any one of claims 14 to 18, or the positive electrode sheet according to claim 19, or the battery cell prepared by the method according to claim 20 or 21.

23. An electrical device, comprising: Comprising: The battery cell according to any one of claims 1 to 10, or the positive electrode sheet according to claim 19, or the battery cell prepared by the method according to claim 20 or 21, or the battery device according to claim 22.

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