Preparation method of lithium nickel manganese oxide positive electrode active material, battery monomer, battery device and power utilization device

Abstract

The invention relates to the technical field of batteries, and discloses a preparation method of a lithium nickel manganese oxide positive electrode active material, a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive pole piece, the positive pole piece comprises a positive pole film layer, the positive pole film layer comprises a lithium nickel manganese oxide positive pole active material, in an XRD diffraction pattern of the lithium nickel manganese oxide positive pole active material, the full width at half maximum of a characteristic diffraction peak of a (111) crystal face is 0.1-0.2 degree, the full width at half maximum of a characteristic diffraction peak of a (311) crystal face is 0.1-0.2 degree, and the full width at half maximum of a characteristic diffraction peak of a (311) crystal face is 0.1-0.2 degree. And (400) the full width at half maximum of the characteristic diffraction peak of the crystal face is 0.1-0.2 degree. According to the battery monomer provided by the embodiment of the invention, lattice defects of the positive electrode active material are few, capacity fading can be delayed in the cycle process, and the cycle performance of the lithium ion battery can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a preparation method of a lithium nickel manganese oxide positive electrode active material, a battery monomer, a battery device and a power utilization device. BACKGROUND

[0002] Lithium ion batteries are not only applied to energy storage power systems such as hydraulic, thermal, wind and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, electric vehicles, military equipment and aerospace, and many other fields.

[0003] The continuous development of society puts forward higher requirements for the performance of lithium ion batteries. However, the cycle performance of the current lithium ion battery still needs to be further improved. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a preparation method of a lithium nickel manganese oxide positive electrode active material, a battery monomer, a battery device and a power utilization device. The battery monomer provided by the embodiments of the present application has few lattice defects of the positive electrode active material, can delay capacity decay in the cycle process, and can significantly improve the cycle performance of the lithium ion battery.

[0005] In a first aspect, the present application provides a battery monomer, comprising a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode film layer, and the positive electrode film layer comprises a lithium nickel manganese oxide positive electrode active material, wherein in the XRD diffraction pattern of the lithium nickel manganese oxide positive electrode active material, the half-height width of the characteristic diffraction peak of the (111) crystal face is 0.1°-0.2°, the half-height width of the characteristic diffraction peak of the (311) crystal face is 0.1°-0.2°, and the half-height width of the characteristic diffraction peak of the (400) crystal face is 0.1°-0.2°.

[0006] In the embodiments of the present application, the half-height width of the characteristic diffraction peak of the (111) crystal face, the (311) crystal face and the (400) crystal face of the lithium nickel manganese oxide positive electrode active material is small, the lattice defect of the lithium nickel manganese oxide positive electrode active material is small, on the one hand, the crystal structure is regular, the migration resistance of lithium ion during embedding / extraction in the charge / discharge process is small, which helps to improve the diffusion coefficient of Li⁺; on the other hand, the crystal structure is stable, which can reduce the loss of manganese and inhibit the distortion of the crystal structure. Therefore, through the effects of the two aspects, the capacity decay can be delayed in the cycle process, thereby significantly improving the cycle performance of the lithium ion battery.

[0007] In some embodiments, the grain size of the (111) crystal face is 60nm-120nm.

[0008] In the embodiments of the present application, the lithium nickel manganese oxide has a spinel layered structure, the (111) crystal plane is perpendicular to the main channel (interlayer direction) of lithium ion diffusion, the grain size of the (111) crystal plane is within the above defined range, the interlayer arrangement is more regular, the path of lithium ion diffusion along the interlayer is more unobstructed, the migration resistance of lithium ion can be reduced, which helps to further reduce the capacity attenuation of the battery during the cycle process and improve the cycle performance of the battery.

[0009] In some embodiments, the crystallinity of the (111) crystal plane is 85%-98%.

[0010] In the embodiments of the present application, the high crystallinity of the (111) crystal plane can make the active site distribution on the material surface more uniform, the interfacial reaction between the electrolyte and the material surface more stable and reversible, and the interfacial impedance stability reduced, thereby helping to improve the overall performance and cycle life of the battery.

[0011] In some embodiments, the lithium nickel manganese oxide positive electrode active material contains a first doping element and a second doping element; wherein the first doping element includes one or more of Al, Ga, Zr, Hf, Ti, and the second doping element includes one or more of Nb and V.

[0012] In the embodiments of the present application, the bond energy between the first doping element and oxygen element is much larger than the bond energy of Ni-O bond and much larger than the bond energy of Mn-O bond. Doping the first doping element into the lithium nickel manganese oxide crystal lattice can reduce the surface potential and effectively control the ratio of ordered (P4332 space group) / disordered (Fd3m space group) structure in the lithium nickel manganese oxide, balance the contradiction between the capacity and cycle retention rate of the positive electrode active material, and thus help to improve the cycle performance of the battery. The second doping element has a high valence and a small ionic radius, can partially replace Ni²⁺ and / or Mn³⁺ in the transition metal layer, can enhance the electrostatic interaction between ions in the crystal lattice, and can reduce the interlayer sliding trend. Therefore, during high-voltage charging and discharging, the phase transition of the layered structure to spinel or rock salt phase is inhibited, the structure collapse is reduced, and the cycle life of the battery is further improved.

[0013] In some embodiments, the chemical formula of the lithium nickel manganese oxide positive electrode active material is Li 0.8-1.2 Ni 0.5-x Mn 1.5- y M x M’ y O4, wherein M represents the first doping element, M’ represents the second doping element, 0.005≤x≤0.018, and 0.008≤y≤0.02.

[0014] In the embodiments of the present application, the doping amount of the first doping element and the second doping element is within a limited range, the crystal structure is more stable, and the cycle performance of the lithium ion battery is better.

[0015] In some embodiments, the lithium nickel manganese oxide positive electrode active material further comprises a carbon coating layer; wherein the carbon coating layer is coated on the surface of the lithium nickel manganese oxide containing the first doping element and the second doping element.

[0016] In the embodiments of the present application, carbon coating is performed on the lithium nickel manganese oxide positive electrode active material, which can further reduce the oxidative decomposition of the electrolyte on the surface of the lithium nickel manganese oxide, and help to further improve the cycle performance of the battery.

[0017] In some embodiments, the mass percentage of carbon elements in the lithium nickel manganese oxide positive electrode active material is 0.8%-1.9% based on the total mass of the lithium nickel manganese oxide positive electrode active material.

[0018] In the embodiments of the present application, the mass percentage of carbon elements in the lithium nickel manganese oxide positive electrode active material is within the above range, and the cycle performance of the battery is better.

[0019] In some embodiments, in the Raman spectrum of the carbon coating layer, I D / I G <0.5; wherein I D is the intensity of the D peak, and I G is the intensity of the G peak.

[0020] In the embodiments of the present application, in the Raman spectrum of the carbon coating layer, I D / I G <0.5, the graphitization degree of carbon in the carbon coating layer is high, and the SP 2 hybrid conjugated structure can form a continuous conductive network, reduce the contact resistance inside the electrode, can significantly improve the electronic transmission capacity of the lithium nickel manganese oxide positive electrode material, reduce the polarization effect during large current charging and discharging, and help to improve the capacity retention rate of the battery.

[0021] In a second aspect, the present application provides a preparation method of a lithium nickel manganese oxide positive electrode active material, wherein the method comprises: first pressing raw materials including a lithium source, a nickel source and a manganese source into a block to obtain a raw material block, and then using the raw material block as an anode for direct current arc plasma treatment to obtain the lithium nickel manganese oxide positive electrode active material.

[0022] In the embodiments of the present application, the block obtained by pressing the raw material including the lithium source, the nickel source and the manganese source is used as the anode of the arc discharge, the raw material is gasified and evaporated, the raw material directly contacts in the gas phase at a temperature of 3000-4000 ℃, and the atomic level reaction occurs. Compared with the solid phase diffusion, the half-height width of the characteristic diffraction peak of the (111) crystal face, the characteristic diffraction peak of the (311) crystal face and the characteristic diffraction peak of the (400) crystal face in the XRD diffraction pattern of the lithium nickel manganese oxide positive electrode active material generated by crystallization in the present application is 0.1-0.2° respectively, the lattice defects are less, the grain size of the (111) crystal face is smaller, and the crystallinity is higher, so that the capacity attenuation in the cycle process can be delayed, and the cycle performance of the lithium ion battery can be significantly improved.

[0023] In some embodiments, the method further comprises: first pressing the raw material including the lithium source, the nickel source, the manganese source, the first doping element and the second doping element into a block to obtain a raw material block, and then using the raw material block as the anode of the arc discharge to perform the direct current arc plasma treatment to obtain the lithium nickel manganese oxide positive electrode active material.

[0024] In the embodiments of the present application, the doping of the first doping element and the second doping element helps to further improve the cycle performance of the lithium ion battery.

[0025] In some embodiments, the method further comprises: first pressing the raw material including the lithium source, the nickel source, the manganese source, the first doping element and the second doping element into a block to obtain a raw material block, and then using the raw material block as the anode of the arc discharge to contact with the carbon source gas to perform the direct current arc plasma treatment to obtain the lithium nickel manganese oxide positive electrode active material.

[0026] In the embodiments of the present application, the carbon coating layer with a high degree of graphitization can be prepared by using the direct current arc plasma to perform the carbon coating on the lithium nickel manganese oxide positive electrode active material, which helps to further improve the electronic conductivity of the lithium ion battery.

[0027] In a third aspect, the present application provides a battery device comprising the battery monomer of the first aspect of the present application. Therefore, the battery device has all the features and advantages of the battery monomer described above, which will not be repeated here.

[0028] In a fourth aspect, the present application provides a power consuming device comprising the battery monomer of the first aspect of the present application or the battery device of the second aspect of the present application. Therefore, the power consuming device has all the features and advantages of the battery monomer described above, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments of the present disclosure will be briefly introduced. Obviously, the drawings described below are only some of the embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative effort on the basis of the drawings.

[0030] Figure 1 A schematic diagram of a battery cell provided for some embodiments of the present application; Figure 2 A schematic diagram of an electric device provided for some embodiments of the present application; Figure 3 An XRD pattern of a lithium nickel manganese oxide positive electrode active material prepared in some embodiments of the present application; Figure 4 An SEM pattern of a lithium nickel manganese oxide positive electrode active material prepared in some embodiments of the present application; Figure 5 A TEM pattern of a lithium nickel manganese oxide positive electrode active material prepared in some embodiments of the present application; Figure 6 An EDS-mapping pattern of a lithium nickel manganese oxide positive electrode active material prepared in some embodiments of the present application; Figure 7 An EDS-mapping pattern of a lithium nickel manganese oxide positive electrode active material prepared in Comparative Example 1 of the present application; Figure 8 A Raman spectrum of a lithium nickel manganese oxide positive electrode active material prepared in some embodiments of the present application. DETAILED DESCRIPTION

[0031] Hereinafter, specific embodiments of the negative current collector, the battery cell, the battery device and the electric device of the present application are specifically disclosed with appropriate reference to the drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters known to those skilled in the art, repeated description of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0032] The ranges disclosed herein are defined by their lower and upper endpoints, and given that a range is defined by selecting a lower endpoint and an upper endpoint, the selected lower and upper endpoints define the boundaries of the particular range. Ranges defined by endpoints can be inclusive or exclusive of the endpoints, and can be arbitrarily combined, i.e., any lower endpoint can be combined with any upper endpoint to form a range. For example, if ranges of 60-120 and 80-110 are listed, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present disclosure, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing all of the individual real combinations of values that are within the range of a to b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all of the real numbers between 0 and 5 have been listed herein, and "0-5" is merely a shorthand way of describing those numerical combinations. In addition, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, all embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the content of the present disclosure.

[0034] Unless otherwise specified, all technical features and optional technical features of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the content of the present disclosure.

[0035] Unless otherwise specified, all steps of the present disclosure can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can also comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0036] In the present disclosure, the terms "plurality" and "plural" refer to two or more.

[0037] In the description of the embodiments of the present disclosure, if there is no special indication, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be above or obliquely above the second feature, or it can only mean that the first feature is higher than the second feature in horizontal height. The first feature can be below or obliquely below the second feature, or it can only mean that the first feature is lower than the second feature in horizontal height.

[0038] Next, the embodiments of the present application are introduced.

[0039] In the continuous evolution of lithium ion battery technology, the selection of battery positive active material is one of the keys to promote the breakthrough of battery performance. Spinel lithium nickel manganese oxide is one of the potential positive materials and has received extensive attention. However, the battery prepared by using spinel lithium nickel manganese oxide is prone to capacity attenuation during the cycle process, which makes the cycle performance of lithium ion battery decline.

[0040] Therefore, the present application provides a preparation method of lithium nickel manganese oxide positive active material, a battery monomer, a battery device and a power utilization device. The battery monomer provided by the embodiments of the present application has few lattice defects of the positive active material, can delay capacity attenuation during the cycle process, and can significantly improve the cycle performance of the lithium ion battery.

[0041] Battery monomer The present application provides a battery monomer, which can be a secondary battery. The secondary battery refers to a battery monomer that can be activated by charging after discharging. The battery monomer comprises an electrode assembly, an electrolyte and a shell. The electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator, and the separator is arranged between the positive electrode sheet and the negative electrode sheet.

[0042] Positive electrode sheet In some embodiments, the positive electrode sheet comprises a positive electrode film layer, and the positive electrode film layer comprises a lithium nickel manganese oxide positive active material. In the XRD diffraction spectrum of the lithium nickel manganese oxide positive active material, the half-height width of the characteristic diffraction peak of the (111) crystal face is 0.1°-0.2°, the half-height width of the characteristic diffraction peak of the (311) crystal face is 0.1°-0.2°, and the half-height width of the characteristic diffraction peak of the (400) crystal face is 0.1°-0.2°.

[0043] During the charge and discharge cycle of the battery, Mn 3+ in the lithium nickel manganese oxide will undergo disproportionation reaction to generate Mn 2+ and Mn 4+, partial loss of manganese will cause distortion of the crystal structure of lithium nickel manganese oxide. In addition, lithium nickel manganese oxide will form high concentration of Ni 4+ , which will aggravate the oxidative decomposition of the electrolyte on the electrode surface and form an interface film on the electrode surface, hindering the deintercalation of lithium ions. All the above will cause capacity attenuation during the cycle process, resulting in a decrease in the cycle performance of lithium ion batteries.

[0044] In the embodiments of the present application, the half-height width of the characteristic diffraction peaks of the (111) crystal plane, the (311) crystal plane and the (400) crystal plane of the lithium nickel manganese oxide positive electrode active material is small, the lithium nickel manganese oxide positive electrode active material has few lattice defects. On the one hand, the crystal structure is regular, the migration resistance of lithium ions during intercalation / deintercalation in the charge / discharge process is small, which helps to improve the diffusion coefficient of Li⁺; on the other hand, the crystal structure is stable, which can reduce the loss of manganese and inhibit the distortion of the crystal structure. As a result, through the above two effects, the capacity attenuation during the cycle process can be delayed, thereby significantly improving the cycle performance of lithium ion batteries.

[0045] The test method of the characteristic diffraction peaks of the crystal plane of the positive electrode active material in the battery cell is as follows: disassemble the battery cell, take out the positive electrode sheet, clean with DMC and dry, scrape off the positive electrode film layer for XRD detection. The test results are calibrated and the peak shape is fitted, and the half-height width of each crystal plane is read.

[0046] In some embodiments, the half-height width of the characteristic diffraction peaks of the (111) crystal plane, the (311) crystal plane and the (400) crystal plane can be independently selected from 0.1°, 0.11°, 0.12°, 0.13°, 0.14°, 0.15°, 0.16°, 0.17°, 0.18°, 0.19°, 0.2°, and any number between these values. Alternatively, the half-height width of the characteristic diffraction peaks of the (111) crystal plane, the (311) crystal plane and the (400) crystal plane can be independently selected from 0.1°-0.15°. As a result, the lithium nickel manganese oxide positive electrode active material has a higher diffusion coefficient of Li⁺ and less crystal structure distortion, which helps to further improve the cycle performance of lithium ion batteries.

[0047] In some embodiments, the grain size of the (111) crystal plane is 60nm-120nm. For example, the grain size of the (111) crystal plane can be 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, and any number between these values. Alternatively, the grain size of the (111) crystal plane is 80nm-120nm.

[0048] In the embodiments of the present application, the grain size of the (111) crystal face can be calculated according to the XRD test results of the positive electrode active material in combination with the Scherrer formula. The lithium nickel manganese oxide belongs to a spinel layered structure, the (111) crystal face is perpendicular to the main channel (interlayer direction) of lithium ion diffusion, the grain size of the (111) crystal face is within the range defined above, the interlayer arrangement is more regular, the path of lithium ion diffusion along the interlayer is more unobstructed, the migration resistance of lithium ion can be reduced, which helps to further reduce the capacity attenuation of the battery during the cycle process and improve the cycle performance of the battery.

[0049] In some embodiments, the crystallinity of the (111) crystal face is 85%-98%. For example, the crystallinity of the (111) crystal face can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and any number between these values. Optionally, the crystallinity of the (111) crystal face is 90%-98%.

[0050] In the embodiments of the present application, the crystallinity of the (111) crystal face can be calculated according to the XRD test results of the positive electrode active material in combination with the standard sample of lithium nickel manganese oxide using the integral intensity method. High crystallinity of the (111) crystal face can make the active site distribution on the material surface more uniform, the interfacial reaction between the electrolyte and the material surface more stable and reversible, reduce the interfacial impedance stability, and further improve the overall performance and cycle life of the battery.

[0051] In some embodiments, the lithium nickel manganese oxide positive electrode active material contains a first doping element and a second doping element; wherein the first doping element includes one or more of Al, Ga, Zr, Hf, Ti, and the second doping element includes one or more of Nb and V.

[0052] In the embodiments of the present application, the bond energy between the first doping element and the oxygen element is much larger than the bond energy of Ni-O bond and much larger than the bond energy of Mn-O bond. Doping the first doping element into the lithium nickel manganese oxide crystal lattice can reduce the surface potential, effectively control the ratio of ordered (P4332 space group) / disordered (Fd3m space group) structure in the lithium nickel manganese oxide, balance the contradiction between the capacity and the cycle retention rate of the positive electrode active material, and thus help to improve the cycle performance of the battery. The second doping element has a high valence and a small ionic radius, can partially replace Ni²⁺ and / or Mn³⁺ in the transition metal layer, can enhance the electrostatic interaction between ions in the crystal lattice, reduce the interlayer slip trend, and inhibit the lattice distortion. During high-voltage charging and discharging, the phase change of the layered structure to spinel or rock salt phase can be inhibited, the change in the unit cell volume caused by Li⁺ deintercalation during the charging and discharging process can be reduced, the risk of structure collapse can be reduced, and the cycle life can be further improved.

[0053] In some embodiments, the lithium nickel manganese oxide cathode active material has a chemical formula of Li 0.8-1.2 Ni 0.5-x Mn 1.5- y M x M’ y O4, wherein M represents a first doping element, M’ represents a second doping element, 0.005≤x≤0.018, and 0.008≤y≤0.02.

[0054] In the embodiments of the present application, the first doping element and the second doping element and their doping amounts can be tested by an inductively coupled plasma optical emission spectrometer. The doping amounts of the first doping element and the second doping element are within a limited range, the crystal structure is more stable, and the cycle performance of the lithium ion battery is better. x can be 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, and any number between these values. y can be 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.02, and any number between these values. Optionally, 0.008≤x≤0.015, and 0.01≤y≤0.015. As an example, the chemical formula of the lithium nickel manganese oxide cathode active material can be Li 0.97 Ni 0.485 Mn 1.485 Al 0.015 Nb 0.015 O4, Li 0.98 Ni 0.49 Mn 1.49 Al 0.01 Nb 0.01 O4, Li 0.987 Ni 0.495 Mn 1.492 Al 0.005 Nb 0.008 O4, etc.

[0055] In some embodiments, the lithium nickel manganese oxide cathode active material further comprises a carbon coating layer, wherein the carbon coating layer is coated on the surface of the lithium nickel manganese oxide containing the first doping element and the second doping element.

[0056] In the embodiments of the present application, the carbon-coated nickel-manganese acid lithium positive electrode active material can form an inert coating layer on the surface of the material, which can block the direct contact between the electrolyte and the positive electrode active material, further reduce the oxidative decomposition of the electrolyte on the surface of the nickel-manganese acid lithium, reduce the deposition of byproduct on the surface of the particles, maintain the ion conduction efficiency of the interface, and help to further improve the cycle performance of the battery.

[0057] In some embodiments, the mass percentage of carbon elements in the nickel-manganese acid lithium positive electrode active material is 0.8%-1.9% based on the total mass of the nickel-manganese acid lithium positive electrode active material. For example, the mass percentage of carbon elements in the nickel-manganese acid lithium positive electrode active material can be 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, and any number between these values. Alternatively, the mass percentage of carbon elements in the nickel-manganese acid lithium positive electrode active material is 0.9%-1.1%.

[0058] In the embodiments of the present application, the mass percentage of carbon elements in the nickel-manganese acid lithium positive electrode active material can be tested by thermogravimetric analysis using a TGA / SDTA851e thermogravimetric analyzer of Mettler-Toledo Company, Switzerland. When the mass percentage of carbon elements in the nickel-manganese acid lithium positive electrode active material is within the above range, the cycle performance of the battery is better.

[0059] In some embodiments, in the Raman spectrum of the carbon coating layer, I D / I G <0.5; wherein I D is the intensity of the D peak, and I G is the intensity of the G peak.

[0060] In the embodiments of the present application, in the Raman spectrum of the carbon coating layer, I D / I G <0.5, the graphitization degree of carbon in the carbon coating layer is higher, and the SP 2 hybrid conjugated structure can form a continuous conductive network, reduce the contact resistance inside the electrode, significantly improve the electronic transport capacity of the nickel-manganese acid lithium positive electrode material, reduce the polarization effect during large-current charging and discharging, and help to improve the capacity retention rate of the lithium ion battery.

[0061] In a second aspect, the present application provides a preparation method of a nickel-manganese acid lithium positive electrode active material, wherein the method comprises: first pressing raw materials including a lithium source, a nickel source, and a manganese source into a block to obtain a raw material block, and then using the raw material block as an anode for direct current arc plasma treatment to obtain the nickel-manganese acid lithium positive electrode active material.

[0062] In the embodiments of the present application, the block obtained by pressing raw materials including a lithium source, a nickel source and a manganese source as an anode for arc discharge can gasify and evaporate the raw materials, and the raw materials directly contact each other in a gas phase at a temperature of 3000-4000 °C to generate atomic-level reactions. Compared with solid-phase diffusion, in the XRD diffraction pattern of the lithium nickel manganese oxide positive electrode active material generated by crystallization in the present application, the half-height width of each of the (111) crystal face characteristic diffraction peak, the (311) crystal face characteristic diffraction peak and the (400) crystal face characteristic diffraction peak is independently 0.1-0.2 °, the crystal lattice defects are less, the grain size of the (111) crystal face is smaller, and the crystallinity is higher, which can delay the capacity attenuation in the cycle process and significantly improve the cycle performance of the lithium ion battery.

[0063] In some embodiments, the lithium source can be one or more of Li2CO3, Li2C2O4, LiOH, LiH2PO4; the manganese source can be one or more of MnO, Mn2O3, MnO2, Mn3O4; and the nickel source can be one or more of NiO, Ni2O3, Ni3O4.

[0064] In some embodiments, the amount of the nickel source and the manganese source is added according to the stoichiometric number in the chemical formula Li 0.8-1.2 Ni 0.5-x Mn 1.5-y M x M’ y O4.

[0065] In some embodiments, the cathode for the direct current arc plasma treatment is selected from tungsten or molybdenum.

[0066] In the embodiments of the present application, the tungsten or molybdenum is selected as the cathode for arc discharge, which can reduce the reduction reaction of the lithium source, the nickel source and the manganese source at high temperature, and is helpful for synthesizing the positive electrode active material with the element composition satisfying the aforementioned Li 0.8-1.2 Ni 0.5-x Mn 1.5-y M x M’ y O4.

[0067] In some embodiments, the operating conditions of the direct current arc plasma treatment include that the arc current is 80-120 A, the arc voltage is 20-30 V, and the arc power is 1.6-3.6 kW.

[0068] In the embodiments of the present application, when the operating conditions of the direct current arc plasma treatment are within the above-mentioned range, uniform heating can be achieved, the generation of crystal lattice defects can be reduced, and the cycle performance of the battery can be further improved.

[0069] In some embodiments, the arc current can be 80 A, 85 A, 90 A, 95 A, 100 A, 105 A, 110 A, 115 A, 120 A, and any number between these values. The arc voltage can be 20 A, 21 A, 22 A, 23 A, 24 A, 25 A, 26 A, 27 A, 28 A, 29 A, 30 A, and any number between these values. The arc power can be 1.6 kW, 1.8 kW, 2.0 kW, 2.2 kW, 2.4 kW, 2.6 kW, 2.8 kW, 3 kW, 3.2 kW, 3.4 kW, 3.6 kW, and any number between these values. Alternatively, the arc current is 80 A-100 A, the arc voltage is 24 V-28 V, and the arc power is 1.8 kW-2.8 kW. In this way, the prepared lithium nickel manganese oxide positive electrode active material has fewer lattice defects.

[0070] In some embodiments, the method further comprises: first pressing raw materials including a lithium source, a nickel source, a manganese source, a first doping element, and a second doping element into a block to obtain a raw material block, and then using the raw material block as an anode for arc discharge to perform direct current arc plasma treatment to obtain the lithium nickel manganese oxide positive electrode active material.

[0071] In the embodiments of the present application, the doping of the first doping element and the second doping element helps to further improve the cycle performance of the battery.

[0072] In some embodiments, the first doping element includes one or more of Al, Ga, Zr, Hf, and Ti, and the second doping element includes one or more of Nb and V. The doping amount of the first doping element and the second doping element can satisfy the aforementioned chemical formula Li 0.8-1.2 Ni 0.5-x Mn 1.5-y M x M’ y O4.

[0073] In some embodiments, the method further comprises: first pressing raw materials including a lithium source, a nickel source, a manganese source, a first doping element, and a second doping element into a block to obtain a raw material block, and then using the raw material block as an anode for arc discharge to contact with a carbon source gas to perform direct current arc plasma treatment to obtain the lithium nickel manganese oxide positive electrode active material.

[0074] In the embodiments of the present application, the introduction of the carbon source gas can form a carbon coating layer on the surface of the lithium nickel manganese oxide containing the first doping element and the second doping element. The carbon coating layer can further reduce the oxidative decomposition of the electrolyte on the surface of the lithium nickel manganese oxide, and help to further improve the cycle performance of the battery.

[0075] In some embodiments, the carbon source gas comprises a dilution gas and an organic carbon source; wherein the dilution gas is selected from nitrogen and / or argon; the organic carbon source is selected from one or more of methane, ethylene, acetylene, propane, methanol, ethanol, propylene, butane, butylene; and the volume ratio of the dilution gas and the organic carbon source is 2-8:1. Optionally, the volume ratio of the dilution gas and the organic carbon source is 3-5:1.

[0076] In the embodiments of the present application, carbon coating is performed by using direct current arc plasma treatment. On the one hand, the carbon coating layer has improved bonding strength, and a thin and continuous carbon coating layer is formed on the surface of the particles, thereby helping to reduce the oxidative decomposition of the electrolyte on the surface of the lithium nickel manganese oxide; on the other hand, a carbon coating layer with a high degree of graphitization can be prepared, which helps to improve the electronic transmission capacity of the lithium nickel manganese oxide positive electrode material, reduce the polarization effect during high-current charging and discharging, and improve the capacity retention rate of the battery.

[0077] In some embodiments, the positive electrode film layer further optionally comprises a conductive agent. As an example, the conductive agent can comprise at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0078] In some embodiments, the positive electrode film layer further optionally comprises a binder. As an example, the binder can comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0079] In some embodiments, the positive electrode tab further comprises a current collector. The positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector. The current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector can comprise a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector 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 base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0080] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector; and subjecting the positive electrode current collector to drying, cold pressing, and the like to obtain the positive electrode sheet.

[0081] Negative electrode sheet In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0082] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0083] In some embodiments, the negative electrode active material can be a negative electrode active material known in the art for use in a battery. As an example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0084] In some embodiments, the negative electrode film layer can further optionally include a binder. As an example, the binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0085] In some embodiments, the negative electrode film layer further optionally includes a conductive agent. As an example, the conductive agent can be selected from at least one of super-P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0086] In some embodiments, the negative electrode film layer further optionally includes other additives, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0087] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative electrode current collector, and after drying, cold pressing, and the like, the negative electrode sheet is obtained.

[0088] Separator film In some embodiments, the battery cell further includes a separator film.

[0089] In some embodiments, the separator film is disposed between the positive electrode sheet and the negative electrode sheet. The type of the separator film is not particularly limited in the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0090] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0091] In some embodiments, an inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can be applied on the surface of the separator film.

[0092] Electrolyte In some embodiments, the battery cell further includes an electrolyte. The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The type of the electrolyte is not particularly limited in the present application, and can be selected according to the needs. For example, the electrolyte can be in a liquid state, a gel state, or a solid state.

[0093] In some embodiments, the electrolyte is in a liquid state, and includes an electrolyte salt and a solvent.

[0094] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorodioxalate phosphate.

[0095] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, methyl ethyl sulfone, and diethyl sulfone.

[0096] In some embodiments, the electrolyte solution can further optionally include an additive. As an example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can further include an additive capable of improving certain performance of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature or low-temperature performance of the battery, etc.

[0097] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be made into an electrode assembly through a winding process or a stacking process.

[0098] The housing In some embodiments, the battery cell can further include a housing.

[0099] In some embodiments, the battery cell can include a housing. The housing can be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film, etc. In some embodiments, the housing can be a sealed structure or a non-sealed structure. As an example, when the housing is a non-sealed structure, the housing serves to protect the electrode assembly, and a sealing bag is further included between the housing and the electrode assembly, the sealing bag being used to package the electrode assembly and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating member or an aluminum-plastic film. When the housing is a sealed structure, the housing is used to package the electrode assembly and the electrolyte, etc.

[0100] In some embodiments, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, and the prismatic battery cell includes a square battery cell, a blade battery cell, a multi-prismatic battery cell (e.g., a hexagonal battery cell), etc., without particular limitation.

[0101] In some embodiments, the housing includes an end cap and a housing body, the housing body being provided with an opening, and the end cap being provided on the opening. The housing body can be provided with one or more openings. The end cap can also be provided with one or more openings.

[0102] Method of manufacturing a battery cell In some embodiments, the battery cell is prepared by a known method. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte are assembled to form the battery cell. As an example, the positive electrode sheet, the separator, the negative electrode sheet are wound to form an electrode assembly, for example, the positive electrode sheet, the separator, the negative electrode sheet are wound on a winding mandrel to form a cylindrical structure, and the winding mandrel is removed and the cylindrical structure is flattened to form a wound cell. The electrode assembly is placed in an outer package, dried, and then the electrolyte is injected, and the battery cell is obtained after vacuum packaging, standing, formation and other processes.

[0103] The battery cell mentioned in the embodiments of the present disclosure can realize the function of charging and discharging alone. The battery cell can be a cuboid or other shapes. For example, Figure 1 The battery cell 5 is a cuboid structure as an example.

[0104] Battery apparatus The present application provides a battery apparatus comprising the battery cell described in the foregoing. Therefore, the battery apparatus has all the features and advantages of the battery cell described in the foregoing, which will not be repeated here.

[0105] The battery apparatus mentioned in the embodiments of the present application can comprise one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can comprise a plurality of battery cells connected in series, in parallel or in a mixed manner by a busbar component.

[0106] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of battery cells.

[0107] As an example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells by a cable tie.

[0108] In some embodiments, the battery apparatus can be a battery pack comprising a box body and one or more battery cell assemblies accommodated in the box body.

[0109] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the box body by fixing the battery module in the box body.

[0110] As an example, the battery cell assembly can also be accommodated in the box body by directly fixing a plurality of battery cells in the box body.

[0111] As an example, the case can include a first case and a second case. The first case and the second case are fastened so that an inside of the case forms a closed space to accommodate the battery cell assembly. The closed here means covered or closed, which can be sealed or unsealed. The first case can be a top cover or a bottom plate.

[0112] As an example, the case can include a top cover, a frame and a bottom plate. The top cover and the bottom plate are connected with the frame respectively so that an inside of the case forms a closed space to accommodate the battery cell assembly.

[0113] In some embodiments, the case can be part of a chassis structure of a vehicle. For example, part of the case can be at least part of a floor of the vehicle, or part of the case can be at least part of a cross beam and a longitudinal beam of the vehicle.

[0114] The technical solutions described in the embodiments of the present disclosure are applicable to various electric devices using battery cells and battery devices, for example, but not limited to, mobile devices (such as mobile phones, tablet computers, notebook computers, 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. The battery cells and battery devices are used to store or provide electric energy.

[0115] Electric device The present application provides an electric device comprising the battery cell described above or the battery device described above. Therefore, the electric device has all the features and advantages of the battery cell described above, which will not be repeated here. Figure 2 is a schematic diagram of an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0116] The battery cell of the present application will be described in detail below in combination with specific embodiments.

[0117] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0118] The present application can use conventional techniques of inorganic chemistry within the skill of the art. In the following examples, efforts have been made to ensure accuracy with respect to numbers (amounts, temperature, reaction times, etc.) but some experimental errors and deviations should be accounted for. The temperatures used in the following examples are expressed in °C, and the pressure is atmospheric or close to atmospheric. All reagents were obtained at AR grade. Unless otherwise indicated, all reagents were obtained from commercial channels.

[0119] Preparation Example 1 of lithium nickel manganese oxide cathode active material (1) 37.53 g of NiO, 65.53 g of Mn2O3, 36.39 g of Li2CO3, 1.02 g of Al2O3 and 2.67 g of Nb2O5 were mixed uniformly and pressed into a block which was placed on a copper seat of a direct current arc furnace as an anode for arc discharge, and a tungsten rod was used as a cathode. The distance between the two poles was adjusted to 10 mm; (2) The reaction chamber was vacuumed to about 10 -2 Pa, and then nitrogen and methane were filled in at a volume ratio of 4:1 to reach 2×10 4 Pa and 0.5×10 4 Pa, respectively; (3) The cooling water system was started, the power was turned on and the arc was started. The anode was evaporated at a current of 90 A, a voltage of 26 V and an arc power of 2.34 kW, and direct current arc plasma treatment was carried out; (4) The whole preparation process lasted for 0.5 h. After the reaction was completed, the power was turned off, the temperature was reduced to room temperature, and the cooling water system was turned off to obtain the lithium nickel manganese oxide cathode active material.

[0120] Preparation Example 2 of lithium nickel manganese oxide cathode active material The same as Preparation Example 1 of lithium nickel manganese oxide cathode active material, except that the amount of methane filled was 0.25×10 4 Pa.

[0121] Preparation Example 3 of lithium nickel manganese oxide cathode active material The same as Preparation Example 1 of lithium nickel manganese oxide cathode active material, except that the amount of methane filled was 0.75×10 4 Pa.

[0122] Preparation Example 4 of lithium nickel manganese oxide cathode active material The same as Preparation Example 1 of lithium nickel manganese oxide cathode active material, except that the amount of Al doping was 0.005 mol and the amount of Nb doping was 0.008 mol.

[0123] Preparation Example 5 of lithium nickel manganese oxide cathode active material The same as Preparation Example 1 of lithium nickel manganese oxide cathode active material, except that the amount of Al doping was 0.018 mol and the amount of Nb doping was 0.02 mol.

[0124] Preparation Comparative Example 1 of lithium nickel manganese oxide cathode active material The lithium nickel manganese oxide positive electrode active material is prepared by a traditional solid-phase sintering process: 37.53 g of NiO, 65.53 g of Mn2O3, 36.39 g of Li2CO3, 1.02 g of Al2O3, and 2.67 g of Nb2O5 are put into a high-speed mixer and mixed at a speed of 2000 r / min for 0.5 h, and then the mixed material is taken out and put into a sagger, and the sagger is placed in a box furnace under a natural air atmosphere at 850°C for sintering for 10 h, with a heating rate of 5°C / min. After cooling to room temperature, the lithium nickel manganese oxide positive electrode active material is obtained.

[0125] The composition and XRD analysis of the lithium nickel manganese oxide positive electrode active material prepared in the lithium nickel manganese oxide positive electrode active material preparation examples and the lithium nickel manganese oxide positive electrode active material preparation comparative examples are shown in Table 1.

[0126] Test of the chemical formula of the lithium nickel manganese oxide positive electrode material: 0.2 g of the positive electrode active material is weighed into a 100 mL beaker, 10 mL of a 10% w / w nitric acid solution is added, and after heating and digestion at 120°C for 0.5 h, the solution is diluted to 100 mL with a volumetric flask; 1 mL of the solution is then taken with a pipette and diluted to 100 mL with a volumetric flask to obtain the test solution. The mass fraction of lithium, manganese, iron, phosphorus, and doped elements in the test solution is determined by inductively coupled plasma optical emission spectrometry (ICP-OES, instrument brand: Agilent 5800), and the molar ratio of each element in the positive electrode active material is calculated according to the mass fraction of each element in the test solution, so as to determine the chemical formula and element molar ratio of the positive electrode active material.

[0127] Method for testing the half-height width of the characteristic diffraction peak of the (111) crystal plane, the (311) crystal plane, and the (400) crystal plane in the positive electrode active material: XRD characterization of the positive electrode active material is performed by using an XRD-6000 X-ray diffractometer from Shimadzu Corporation, with CuKα as the radiation source (λ = 0.15418 nm), a voltage of 40 kV, a current of 30 mA, a scanning speed of 2° / min, and a scanning angle range of 20°-80°. The test results are subjected to pattern calibration and peak shape fitting, and then the half-height width of the characteristic diffraction peak of each crystal plane is read.

[0128] Method for testing the grain size of the (111) crystal plane in the positive electrode active material: the grain size of the (111) crystal plane is calculated according to the XRD test results of the positive electrode active material and the Scherrer formula. wherein, Scherrer formula D = Kλ / β cos θ - D is the grain size, in nm; - K is the Scherrer constant, usually taken as 0.89; - λ is the X-ray wavelength (λ ≈ 0.15418 nm for Cu Kα radiation; - θ is the diffraction angle of the (111) crystal plane, unit: radian; - β is the half-height width after deducting the instrument broadening.

[0129] Method for testing the crystallinity of the (111) crystal plane in the positive electrode active material: according to the XRD test results of the positive electrode active material and the lithium nickel manganese oxide standard sample, the crystallinity of the (111) crystal plane is calculated. First, select a lithium nickel manganese oxide standard sample with known crystallinity (such as the corresponding data of the JCPDS card), calculate the total integral intensity I std of the characteristic diffraction peak and other main diffraction peaks of the (111) crystal plane; then measure the total integral intensity I sample of the diffraction peak and other main diffraction peaks of the (111) crystal plane of the sample to be tested, and the crystallinity X = I sample / I std * 100%.

[0130] Method for testing the carbon content: the thermal gravimetric analysis is carried out by using the TGA / SDTA851e thermal gravimetric analyzer of Mettler-Toledo Company in Switzerland, the test is carried out in air atmosphere, the temperature range is room temperature-800℃, and the temperature rising rate is 5℃ / min. The mass content of carbon is calculated by using the mass change in the process of thermal gravimetric analysis.

[0131] Method for testing the graphitization degree of carbon in the carbon coating layer: the positive electrode active material powder is pressed into a thin sheet, and a Raman spectrometer (equipment model is Renishaw InVia) is used for testing, the testing laser excitation wavelength is 532 nm; the power is 5 mW; the integral time is 20 s / time; the scanning range is 200-3000 cm⁻¹, covering the main characteristic peak region of carbon material. The intensity I D of the D peak (located at about 1350 cm⁻¹) and the intensity I G of the G peak (located at about 1580 cm⁻¹) are read from the Raman spectrum, and then I D / I G is calculated. The smaller I D / I G is, the higher the graphitization degree of carbon in the carbon coating layer is.

[0132] Figure 3 Figure 1 is the XRD pattern of the lithium nickel manganese oxide positive electrode active material prepared in Example 1 of the lithium nickel manganese oxide positive electrode active material preparation of the present application. From the XRD pattern, it can be seen that the prepared lithium nickel manganese oxide positive electrode active material has a good crystallinity, and the diffraction peak is clear and complete. Figure 3It can be seen that the half-height widths of the (111) crystal plane, (311) crystal plane, and (400) crystal plane are relatively small, below 0.2°, close to the intrinsic width of the instrument (0.1°), indicating that the lattice defects of the lithium nickel manganese oxide positive electrode active material are few. Compared with the lithium nickel manganese oxide standard sample (corresponding data of the JCPDS card), the characteristic diffraction peak of the (111) crystal plane shifted from 18.5° to 18.7°, the characteristic diffraction peak of the (311) crystal plane shifted from 35.6° to 36.3°, and the characteristic diffraction peak of the (400) crystal plane shifted from 43.8° to 44.3°. The shift of the characteristic diffraction peaks indicates that the first doping element and the second doping element have entered the interior of the material lattice. The grain size of the (111) crystal plane with the strongest peak intensity is 83nm, and the crystallinity calculated by the integrated intensity method is 95%.

[0133] The XRD patterns of the lithium nickel manganese oxide positive electrode active materials prepared in Examples 2-5 of the present application are similar to those in Example 3. The characteristic diffraction peaks of the (111) crystal plane, the (311) crystal plane, and the (400) crystal plane are also shifted, with the shift distance being between 0.2-1.0°, and the half-height widths of the characteristic diffraction peaks of the (111) crystal plane, the (311) crystal plane, and the (400) crystal plane are between 0.1-0.2°.

[0134] Figure 8 This is the Raman spectrum of the lithium nickel manganese oxide positive electrode active material prepared in Example 1 of the preparation of the lithium nickel manganese oxide positive electrode active material of this application. Figure 8 It can be seen that I D / I G is 0.36.

[0135] Table 1

[0136] Note: C% refers to the mass percentage of carbon element in the lithium nickel manganese oxide positive electrode active material, that is, the content of the carbon coating layer.

[0137] Test Example 1 The lithium nickel manganese oxide positive electrode active material prepared in the above lithium nickel manganese oxide positive electrode active material preparation example 1 was characterized by SEM and TEM. Figure 4 and Figure 5 shown.

[0138] Among them, Figure 4 It can be seen that the grain size of the positive electrode active material of lithium nickel manganese oxide is between 200-500nm. Figure 5 It can be seen that the carbon coating layer on the surface of lithium nickel manganese oxide is thin and continuous, which helps to reduce the oxidative decomposition of the electrolyte on the surface of lithium nickel manganese oxide.

[0139] The crystal cross section of the lithium nickel manganese oxide positive electrode active material prepared in Example 1 was cut by FIB, and the cross section was subjected to EDS-mapping test by high-resolution SEM. The results are as follows: Figure 6 As shown. The crystal cross section of the lithium nickel manganese oxide positive electrode active material prepared by the traditional solid phase sintering process was cut by FIB, and the cross section was tested by EDS-mapping using high-resolution SEM. The results are as follows Figure 7 As shown in the EDS-mapping diagram, the higher the clarity, the more uniform the element distribution.

[0140] Depend on Figure 6 It can be seen that the preparation method of lithium nickel manganese oxide positive electrode active material provided in this application can achieve atomic-level uniform distribution of doping elements in lithium nickel manganese oxide through high-temperature melting by arc method (DC arc plasma treatment), thereby directly controlling the crystal structure, optimizing ion diffusion channels, and inhibiting phase transition. By comparison Figure 6 and Figure 7 It can be seen that the atomic-level element doping using the arc method is more uniform than the traditional solid-phase sintering process.

[0141] Lithium-ion battery preparation example Positive electrode sheet: The positive electrode active material prepared in Examples 1-5 and Comparative Example 1: conductive carbon black: polyvinylidene fluoride were mixed in a mass ratio of 8:1:1, and then solvent N-methylpyrrolidone was added. The mixture was stirred thoroughly to mix evenly. The positive electrode paste was evenly coated on an aluminum foil pre-wiped with ethanol using a film coater. After drying, cold pressing, and cutting, a positive electrode sheet with a diameter of 14 mm was obtained.

[0142] Negative electrode sheet: Artificial graphite, conductive carbon black, styrene-butadiene rubber and solvent water are evenly mixed in a weight ratio of 95:2:3:100, and coated on a copper foil that has been wiped with ethanol in advance. After drying, cold pressing and cutting, a negative electrode sheet with a diameter of 14 mm is obtained.

[0143] Separator: A polyethylene film with a thickness of 13 μm was used as the separator, which was cut into discs with a diameter of 18 mm when used.

[0144] Electrolyte: Ethylene carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1, and LiPF6 was dissolved in the above solution to obtain an electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0145] Assembling: Put the separator, the prepared positive electrode sheet, the negative electrode sheet and the purchased battery-grade button cell shell (CR2025) into a super-clean glove box. Put the positive electrode sheet, the separator and the negative electrode sheet into the battery shell in sequence, drop in an appropriate amount of electrolyte, then add the spring sheet and the gasket, and then drop in an appropriate amount of electrolyte to assemble a CR2025 button cell. After the battery is closed, press it tightly, take it out of the super-clean glove box, seal it with a sealing machine, and stand for 12 hours before testing.

[0146] Lithium ion battery test example Discharge specific capacity test: The button cell was subjected to cyclic charging and discharging at 0.1C, 0.33C and 1C charging and discharging rates using a Shenzhen Xinwei battery detection system. The test temperature was 25.0℃, and the charging and discharging voltage was 3.0V-4.8V. The charging and discharging capacity of the first cycle was obtained.

[0147] Cycle stability test: The button cell was subjected to cyclic charging and discharging at 1C charging and discharging rate using a Shenzhen Xinwei battery detection system. The cycle number was 500, the test temperature was 25.0℃, and the charging and discharging voltage was 3.0V-4.8V. The capacity retention rate was obtained by dividing the discharge capacity of the last cycle by the discharge capacity of the first cycle.

[0148] Table 2

[0149] As can be seen from Table 2, the capacity retention rate of the battery provided in the present application after 500 cycles is more than 90%, indicating that the lithium nickel-manganese oxide positive active material in the present application can delay capacity decay during the cycle process and can significantly improve the cycle performance of the lithium ion battery.

[0150] In addition, the 0.1C charging specific capacity, 0.1C discharge specific capacity, 0.33C discharge specific capacity and 1C discharge specific capacity of the battery provided in the present application are all higher than those of the battery composed of the lithium nickel-manganese oxide positive active material prepared by the traditional solid-phase sintering process. This is due to the fact that the crystal structure has few defects, the path for lithium ion diffusion between layers is more unobstructed, the migration resistance during intercalation / deintercalation in the charging and discharging process is small, and the crystal structure is stable, which can reduce the loss of manganese and thus inhibit the capacity loss caused by the distortion of the crystal structure.

[0151] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role and effect within the scope of the technical solutions of the present disclosure are all included in the technical scope of the present disclosure. In addition, within the scope of the main idea of the present disclosure, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the components in the embodiments are also included in the scope of the present disclosure.

Claims

1. A battery cell comprising a positive electrode plate, wherein the positive electrode plate comprises a positive electrode film layer, wherein the positive electrode film layer comprises a lithium nickel manganese oxide positive electrode active material, characterized in that: In the XRD diffraction pattern of the lithium nickel manganese oxide positive electrode active material, the half-height width of the characteristic diffraction peak of the (111) crystal plane is 0.1°-0.2°, the half-height width of the characteristic diffraction peak of the (311) crystal plane is 0.1°-0.2°, and the half-height width of the characteristic diffraction peak of the (400) crystal plane is 0.1°-0.2°.

2. The battery cell according to claim 1, wherein: The grain size of the (111) crystal plane is 60nm-120nm.

3. The battery cell according to claim 1, wherein: The crystallinity of the (111) crystal plane is 85%-98%.

4. The battery cell according to claim 1, wherein: The lithium nickel manganese oxide positive electrode active material contains a first doping element and a second doping element; wherein the first doping element includes one or more of Al, Ga, Zr, Hf, and Ti, and the second doping element includes one or more of Nb and V.

5. The battery cell according to claim 4, characterized in that The chemical formula of the lithium nickel manganese oxide positive electrode active material is Li 0.8-1.2 Ni 0.5-x Mn 1.5-y M x M' y O4, wherein M represents a first doping element, M' represents a second doping element, 0.005≤x≤0.018, 0.008≤y≤0.

02.

6. The battery cell according to claim 4 or 5, characterized in that: The lithium nickel manganese oxide positive electrode active material further includes a carbon coating layer, wherein the carbon coating layer is coated on the surface of the lithium nickel manganese oxide containing the first doping element and the second doping element.

7. The battery cell according to claim 6, characterized in that Based on the total mass of the lithium nickel manganese oxide positive electrode active material, the mass percentage of carbon element in the lithium nickel manganese oxide positive electrode active material is 0.8%-1.9%.

8. The battery cell according to claim 6, characterized in that In the Raman spectrum of the carbon coating layer, I D / I G <0.5; among them, I D is the intensity of the D peak, I G is the intensity of the G peak.

9. A method for preparing a lithium nickel manganese oxide positive electrode active material, characterized in that: The method comprises: first pressing raw materials including a lithium source, a nickel source and a manganese source into blocks to obtain raw material blocks, and then using the raw material blocks as anodes for arc discharge to perform DC arc plasma treatment to obtain lithium nickel manganese oxide positive electrode active materials.

10. The method for preparing a lithium nickel manganese oxide positive electrode active material according to claim 9, characterized in that: The method comprises: first pressing raw materials including a lithium source, a nickel source, a manganese source, a first doping element, and a second doping element into blocks to obtain raw material blocks, and then using the raw material blocks as anodes for arc discharge to perform DC arc plasma treatment to obtain lithium nickel manganese oxide positive electrode active materials.

11. The method for preparing a lithium nickel manganese oxide positive electrode active material according to claim 10, characterized in that: The method comprises: first pressing raw materials including a lithium source, a nickel source, a manganese source, a first doping element, and a second doping element into blocks to obtain raw material blocks, then using the raw material blocks as anodes for arc discharge in contact with carbon source gas, and performing DC arc plasma treatment to obtain lithium nickel manganese oxide positive electrode active materials.

12. A battery device, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 8.

13. An electrical device, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 8 or the battery device according to claim 11.

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