Lithium-ion battery, positive electrode active material and preparation method therefor, and electric device

Abstract

The present application provides a lithium-ion battery, a positive electrode active material and a preparation method therefor, and an electric device. The positive electrode active material of the lithium-ion battery comprises a lithium-nickel-based oxide, the lithium-nickel-based oxide comprising Li and non-lithium metal elements; the non-lithium metal elements include Ni, and the molar amount of Ni accounts for more than 20% of the total molar amount of the non-lithium metal elements. In an O1s spectrum obtained by X-ray photoelectron spectroscopy analysis of the lithium-nickel-based oxide, peaks having a binding energy of 528-530 eV account for 12% to 40% of the total peak area.

Description

Lithium-ion batteries, positive electrode active materials and preparation methods, and electrical devices thereof

[0001] Related applications

[0002] This application claims priority to Chinese patent application filed on January 27, 2025, with application number 2025101264857, entitled "Lithium-ion battery, positive electrode active material and preparation method and power device", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and in particular to lithium-ion batteries, positive electrode active materials and preparation methods, and electrical devices. Background Technology

[0004] In recent years, lithium-ion batteries have been widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. With the continuous expansion of the application range of lithium-ion batteries, correspondingly higher requirements are being placed on battery performance.

[0005] In the design of lithium-ion batteries, cycle performance is one of the important indicators for evaluating battery performance. Lithium nickel-based oxides containing Ni are a relatively common positive electrode active material, which has a high specific capacity and is conducive to improving the energy density of batteries. However, when applied to lithium-ion batteries, the cycle performance of the batteries needs to be further improved. Summary of the Invention

[0006] The first aspect of this application provides a lithium-ion battery. The lithium-ion battery includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active layer located on at least one surface of the positive current collector. The positive active material of the positive active layer includes a lithium nickel-based oxide, the lithium nickel-based oxide comprising Li and non-lithium metal elements; the non-lithium metal elements include Ni, the molar amount of Ni accounting for more than 20% of the total molar amount of the non-lithium metal elements, and in the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy, the peak area with a binding energy of 528 eV to 530 eV accounts for 12% to 40%.

[0007] In the lithium-ion battery of this application, the lithium nickel-based oxide with a high Ni content has a high specific capacity, which can enable the battery to have a high energy density. At the same time, in the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy (XPS), the peak area with a binding energy of 528 eV to 530 eV accounts for 12% to 40%, which can maintain a good crystal structure of the lithium nickel-based oxide, reduce the risk of collapse and phase transition during charge and discharge, and thus improve the cycle performance of the battery.

[0008] In some embodiments, when the lithium-ion battery is fully discharged, the oxygen vacancy ratio of the lithium nickel-based oxide is m, the total molar amount of non-oxygen elements in the lithium nickel-based oxide is n1, and the molar amount of oxygen elements in the lithium nickel-based oxide is n2, where m = (n1-n2) / n1 × 100%, and m is less than or equal to 2%. A smaller oxygen vacancy ratio reduces the risk of crystal structure collapse and phase transitions in the lithium nickel-based oxide during charging and discharging, which is beneficial for further improving the battery's cycle performance.

[0009] In some embodiments, when the lithium-ion battery is fully discharged, the XRD pattern of the lithium nickel-based oxide includes diffraction peaks of the (003) crystal plane and diffraction peaks of the (104) crystal plane, wherein the intensity of the diffraction peak of the (003) crystal plane is I. (003) The intensity of the diffraction peak of the (104) crystal plane is I. (104) , where I (003) / I (104) The value is 1.2–1.4. At this point, the layered structure of lithium nickel-based oxides exhibits a high degree of order, which is beneficial for further enhancing the specific capacity of lithium nickel-based oxides and maintaining a relatively stable layered structure, thereby further improving the cycle performance of the battery. Simultaneously, I (003) / I (104) Within this range, the degree of lithium-nickel mixing in lithium-nickel based oxides can be minimized, which is beneficial for promoting the extraction of lithium ions and maximizing the specific capacity of lithium-nickel based oxides.

[0010] In some embodiments, the molar amount of Ni element accounts for a percentage of the total molar amount of the non-lithium metal elements that is greater than or equal to 20% and less than 50%, and the peak area with a binding energy of 528 eV to 530 eV accounts for 25% to 40% of the O1s spectrum of the lithium nickel-based oxide obtained by X-ray photoelectron spectroscopy.

[0011] In some embodiments, when the lithium-ion battery is in a fully discharged state, the Ni element in the lithium nickel-based oxide contains Ni... 3+ The proportion is less than or equal to 35%.

[0012] In some embodiments, the molar amount of Ni element accounts for a percentage of the total molar amount of the non-lithium metal elements that is greater than or equal to 50% and less than 80%, and in the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy, the peak area with a binding energy of 528 eV to 530 eV accounts for 25% to 40%.

[0013] In some embodiments, when the lithium-ion battery is in a fully discharged state, the Ni element in the lithium nickel-based oxide contains Ni... 3+ The proportion ranges from 30% to 87.5%.

[0014] In some embodiments, the molar amount of Ni element accounts for a percentage of the total molar amount of the non-lithium metal elements that is greater than or equal to 80% and less than or equal to 100%, and the peak area with a binding energy of 528 eV to 530 eV in the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy accounts for 10% to 25%.

[0015] In some embodiments, when the lithium-ion battery is in a fully discharged state, the Ni element in the lithium nickel-based oxide contains Ni... 3+ The proportion ranges from 77.5% to 100%.

[0016] The second aspect of this application provides a positive electrode active material, comprising a lithium nickel-based oxide, wherein the lithium nickel-based oxide contains Li and non-lithium metal elements; the non-lithium metal elements include Ni, wherein the molar amount of Ni accounts for more than 20% of the total molar amount of the non-lithium metal elements, and in the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy, the peak area with a binding energy of 528 eV to 530 eV accounts for 12% to 40%.

[0017] The positive electrode active material of this application has a high nickel content, and the peak area ratio in the O1s spectrum of XPS test shows a suitable binding energy of 528 eV to 530 eV. This allows the specific capacity of lithium nickel-based oxides to be fully utilized, while maintaining a good crystal structure and reducing the risk of collapse and phase transition during charge and discharge. Applying this positive electrode active material to lithium-ion batteries can enable the batteries to achieve both high energy density and good cycle performance.

[0018] A third aspect of this application provides a method for preparing a positive electrode active material, comprising the following steps:

[0019] A non-lithium metal hydroxide is mixed with a lithium source and subjected to a first sintering in a first atmosphere including ozone; the non-lithium metal element in the non-lithium metal hydroxide includes Ni element, and the molar amount of Ni element accounts for more than 20% of the total molar amount of non-lithium metal elements in the non-lithium metal hydroxide.

[0020] In the preparation method of the positive electrode active material of this application, during the first sintering, the first atmosphere includes ozone. Ozone can increase the oxygen partial pressure on the surface of the material, inhibit the extraction of oxygen atoms from the lattice of the material surface, increase the lattice oxygen ratio of the lithium nickel-based oxide surface, and thus promote the specific capacity of the lithium nickel-based oxide. Simultaneously, the preparation method of this embodiment can increase the lattice oxygen content of the lithium nickel-based oxide surface, enabling the lithium nickel-based oxide to maintain good structural stability. When this lithium nickel-based oxide is applied to a lithium-ion battery, it can improve the battery's cycle performance.

[0021] In some embodiments, the ozone in the first atmosphere has a volume percentage of 6% to 8%.

[0022] In some embodiments, the temperature of the first sintering is 700°C to 1100°C.

[0023] In some embodiments, the first sintering time is 1 hour to 10 hours.

[0024] Prior to the first sintering, the process further includes: mixing the non-lithium metal hydroxide with the lithium source, and performing a second sintering in a second atmosphere, the second atmosphere including oxygen. The second sintering can pre-sinter the non-lithium metal hydroxide and the lithium source, improving the effect of the first sintering.

[0025] In some embodiments, the temperature of the second sintering is 400°C to 600°C.

[0026] In some embodiments, the second sintering time is 1 hour to 3 hours.

[0027] In some embodiments, the process after the first sintering further includes:

[0028] The material after the first sintering is subjected to a third sintering in a third atmosphere, which includes oxygen.

[0029] In some embodiments, the temperature of the third sintering is 700°C to 1100°C.

[0030] In some embodiments, the third sintering time is 1 hour to 10 hours.

[0031] A fourth aspect of this application provides an electrical device including the lithium-ion battery of the first aspect. Attached Figure Description

[0032] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 is a schematic diagram of a lithium-ion battery according to an embodiment of this application.

[0034] Figure 2 is an exploded view of a lithium-ion battery according to an embodiment of this application, as shown in Figure 1.

[0035] Figure 3 is a schematic diagram of an electrical device using a lithium-ion battery as a power source according to an embodiment of this application.

[0036] Figure 4 shows the Ni 2p spectrum of the XPS of the lithium nickel-based oxide in Example 1 of this application.

[0037] Figure 5 shows the O1s spectrum of XPS for the lithium nickel-based oxide in Example 1 of this application.

[0038] Figure 6 shows the XRD patterns of lithium nickel-based oxides in Example 1 and Comparative Example 1 of this application.

[0039] Figure 7 shows the Ni 2p spectrum of the XPS of the lithium nickel-based oxide in Comparative Example 1 of this application.

[0040] Figure 8 shows the O1s spectrum of the XPS of the lithium nickel-based oxide in Comparative Example 1 of this application.

[0041] Explanation of reference numerals in the attached drawings: 1. Lithium-ion battery; 11. Casing; 12. Electrode assembly; 13. Cover plate; 2. Electrical device. Detailed Implementation

[0042] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] The "range" disclosed in this application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints. Any endpoint can be included or excluded independently, and they can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is expected that ranges of 60–110 and 80–120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are also listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0045] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0046] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0047] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0048] Those skilled in the art will understand that the order in which the steps are written in the methods of various embodiments or examples does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0049] In this application, unless otherwise stated, A (e.g., B) means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0050] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0051] In this application, unless otherwise specified, "lithium-ion battery" refers to a basic unit capable of converting chemical energy into electrical energy, and more generally includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process, active ions repeatedly insert and extract between the positive and negative electrodes. The separator isolates the positive and negative electrodes, enabling the battery to function normally.

[0052] In the design of lithium-ion batteries, lithium nickel-based oxides containing Ni have high specific capacity, which is beneficial to improving battery energy density. However, their structural stability is poor, which makes it difficult to improve the cycle performance of the battery.

[0053] Based on this, one embodiment of this application provides a lithium-ion battery. The lithium-ion battery includes a positive electrode sheet, which includes a positive current collector and a positive active layer located on at least one surface of the positive current collector. The positive active material of the positive active layer includes a lithium nickel-based oxide, which contains Li and non-lithium metal elements. The non-lithium metal elements include Ni, and the molar amount of Ni accounts for more than 20% of the total molar amount of the non-lithium metal elements. In the O1s spectrum of the lithium nickel-based oxide obtained by X-ray photoelectron spectroscopy, the peak area with a binding energy of 528 eV to 530 eV accounts for 12% to 40%.

[0054] In the lithium-ion battery of this application, the lithium nickel-based oxide with a high Ni content has a high specific capacity, which can enable the battery to have a high energy density. At the same time, in the O1s spectrum of the lithium nickel-based oxide obtained by XPS testing, the peak area with a binding energy of 528 eV to 530 eV accounts for 12% to 40%, which can help the lithium nickel-based oxide maintain a good crystal structure, reduce the risk of collapse and phase transition during charge and discharge, and thus improve the cycle performance of the battery.

[0055] It is understandable that in the O1s spectrum of the XPS test of lithium nickel-based oxides, the peak area ratio of the binding energy of 528eV to 530eV is in the range of 12% to 40%. This indicates that the lattice oxygen on the surface of lithium nickel-based oxides has a suitable ratio, which can maintain the good crystal structure of lithium nickel-based oxides, reduce the risk of collapse and phase transition during the charge and discharge process, and thus improve the cycle performance of the battery.

[0056] Optionally, the device used for XPS testing can be the Shimadzu Axis Supra+.

[0057] Furthermore, in the lithium-ion battery of this application, the formation of the rock salt phase on the surface of the lithium nickel-based oxide is suppressed, thereby suppressing the increase in battery impedance and improving the battery's storage performance.

[0058] In this application, the surface layer of the lithium nickel-based oxide refers to a layer of lithium nickel-based oxide with a thickness of less than 20 nm along its outer-to-inner direction. Optionally, the surface layer of the lithium nickel-based oxide can be determined by transmission electron microscopy (TEM). The TEM model can be a Thermo Fisher Talos F200S G2.

[0059] Furthermore, in the O1s spectrum of lithium nickel-based oxides measured by XPS, the peak area with a binding energy of 528eV to 530eV accounts for 12% to 40%, which can reduce lithium-nickel mixing in lithium nickel-based oxides. This can promote the extraction of lithium ions, enabling lithium nickel-based oxides to exhibit higher specific capacity, and allowing lithium-ion batteries to better combine better cycle performance and higher energy density.

[0060] Optionally, in the O1s spectrum of lithium nickel-based oxides measured by XPS, the percentage of peak area with a binding energy of 528 eV to 530 eV can be 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, or any value within the range of any two of the above values.

[0061] In some embodiments, in lithium nickel-based oxides, non-lithium metal elements refer to metal elements other than lithium.

[0062] In some embodiments, the non-lithium metal element in the lithium nickel-based oxide may further include one or more of Co, Mn, Zr, Sr, Sn, Al, Mg, Fe, Cu, V, Ti, Zr, W, Sb, and Dy. Optionally, the non-lithium metal element in the lithium nickel-based oxide may further include one or more of Co and Mn.

[0063] Optionally, in lithium nickel-based oxides, the percentage of the molar amount of Ni element relative to the total molar amount of non-lithium metal elements can be 20%, 30%, 40%, 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 92%, 95%, 98%, 99%, 100%, or any value within the range of any two of the above values.

[0064] In some embodiments, the non-lithium metal element includes a transition metal element. Optionally, the transition metal element includes one or more of Ni, Co, and Mn.

[0065] Optionally, in the lithium nickel-based oxide, the molar amount of Ni accounts for more than 20% of the total molar amount of the transition metal elements. Optionally, in the lithium nickel-based oxide, the percentage of the molar amount of Ni to the total molar amount of the transition metal elements can be 20%, 30%, 40%, 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 92%, 95%, 98%, 99%, 100%, or any value within the range of any two of the above values.

[0066] It is understandable that a 100% molar percentage of Ni in the total molar amount of non-lithium metal elements indicates that the non-lithium metal element in the lithium nickel-based oxide is Ni. In this case, the lithium nickel-based oxide may include lithium nickelate.

[0067] In some embodiments, the oxygen vacancy percentage of the lithium nickel-based oxide is m, the total molar amount of non-oxygen elements in the lithium nickel-based oxide is n1, the molar amount of oxygen elements in the lithium nickel-based oxide is n2, and m = (n1-n2) / n1 × 100%, where m is less than or equal to 2%. A smaller oxygen vacancy percentage reduces the risk of crystal structure collapse and phase transitions in the lithium nickel-based oxide during battery charging and discharging, thus improving the battery's cycle performance. Optionally, the oxygen vacancy percentage of the lithium nickel-based oxide can be 0, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any value within the range of any two of the above values.

[0068] It is understandable that a vacancy rate of 0 in lithium nickel-based oxides means that there are no oxygen vacancies in lithium nickel-based oxides.

[0069] In this application, the oxygen vacancy ratio of lithium nickel-based oxides can be tested in the following way: the molar amount of metal elements is tested using an inductively coupled plasma spectrometer (ICP), the molar amount of non-metal elements is tested using an elemental analyzer, and then the oxygen vacancy ratio m = (n1-n2) / n1×100% is calculated based on the total molar amount of non-oxygen elements n1 and the molar amount of oxygen elements n2 in the lithium nickel-based oxide.

[0070] In some embodiments, the lithium nickel-based oxide comprises a lithium nickel-based oxide having a layered structure. Optionally, the XRD pattern of the lithium nickel-based oxide includes diffraction peaks of the (003) crystal plane and diffraction peaks of the (104) crystal plane, wherein the intensity of the diffraction peak of the (003) crystal plane is I. (003) The intensity of the diffraction peak of the (104) crystal plane is I. (104) , where I (003) / I (104) The value is 1.2–1.4. At this point, the layered structure of lithium nickel-based oxides exhibits a high degree of order, which is beneficial for further enhancing the specific capacity of lithium nickel-based oxides and maintaining a relatively stable layered structure, thereby further improving the cycle performance of the battery. Simultaneously, I (003) / I (104) Within this range, the degree of lithium-nickel mixing in lithium-nickel based oxides can be minimized, which is beneficial for promoting lithium-ion extraction and maximizing the specific capacity of lithium-nickel based oxides. Further optionally, I (003) / I (104)The values ​​are 1.2, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.3, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.4, and any value within the range of any two of the above values. Optionally, the XRD device can be a Bruker D8Advance.

[0071] In some embodiments, the molar amount of Ni is greater than or equal to 20% and less than 50% of the total molar amount of non-lithium metal elements in the lithium nickel-based oxide, and the peak area with a binding energy of 528 eV to 530 eV accounts for 25% to 40% of the O1s spectrum of the lithium nickel-based oxide as measured by X-ray photoelectron spectroscopy.

[0072] Optionally, the molar percentage of Ni in the total molar percentage of non-lithium metal elements in the lithium nickel-based oxide is greater than or equal to 20% and less than 50%. In the fully discharged state of a lithium-ion battery, the Ni element in the lithium nickel-based oxide... 3+ The proportion is less than or equal to 35%.

[0073] It is understandable that the Ni element in lithium nickel-based oxides contains Ni. 3+ The percentage indicates the proportion of Ni in lithium nickel-based oxides. 3+ The atomic ratio of Ni in lithium nickel-based oxides.

[0074] Understandably, the Ni content in lithium nickel-based oxides can be determined from the Ni 2p spectrum obtained by XPS testing. 2+ and Ni 3+ The proportion of Ni in lithium nickel-based oxides. Optionally, in the Ni 2p spectrum obtained by XPS testing, the proportion of the peak area with binding energies of 853 eV to 855.5 eV represents the proportion of Ni in the lithium nickel-based oxide. 2+ The proportion, combined with the peak area proportion of 855.5 eV to 858 eV, indicates the proportion of Ni in lithium nickel-based oxides. 3+ The percentage of Ni in some embodiments is greater than or equal to 50% and less than 80% of the total molar amount of non-lithium metal elements in the lithium nickel-based oxide. In the O1s spectrum of the lithium nickel-based oxide obtained by X-ray photoelectron spectroscopy, the peak area with a binding energy of 528 eV to 530 eV accounts for 25% to 40%.

[0075] Optionally, the molar percentage of Ni in the total molar percentage of non-lithium metal elements in the lithium nickel-based oxide is greater than or equal to 50% and less than 80%. In the fully discharged state of a lithium-ion battery, the Ni element in the lithium nickel-based oxide... 3+ The proportion ranges from 30% to 87.5%.

[0076] In some embodiments, the molar amount of Ni is greater than or equal to 80% and less than or equal to 100% of the total molar amount of non-lithium metal elements in the lithium nickel-based oxide, and the peak area with a binding energy of 528 eV to 530 eV accounts for 10% to 25% of the O1s spectrum of the lithium nickel-based oxide by X-ray photoelectron spectroscopy.

[0077] Optionally, the molar percentage of Ni in the total molar percentage of non-lithium metal elements in the lithium nickel-based oxide is greater than or equal to 80% and less than or equal to 100%. In the fully discharged state of a lithium-ion battery, the Ni element in the lithium nickel-based oxide... 3+ The proportion ranges from 77.5% to 100%.

[0078] Another embodiment of this application provides a positive electrode active material. This positive electrode active material includes a lithium nickel-based oxide, which contains Li and non-lithium metal elements. The non-lithium metal elements include Ni, with the molar amount of Ni accounting for more than 20% of the total molar amount of non-lithium metal elements. In the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy, the peak area with a binding energy of 528 eV to 530 eV accounts for 12% to 40%. This positive electrode active material has a high nickel content, and the peak area ratio of the binding energy of 528 eV to 530 eV in the O1s spectrum measured by XPS is appropriate, which allows the specific capacity of the lithium nickel-based oxide to be fully utilized, while maintaining a good crystal structure and reducing the risk of collapse and phase transition during charge and discharge. Applying this positive electrode active material to lithium-ion batteries can enable the battery to achieve both high energy density and good cycle performance.

[0079] It is understandable that the corresponding parameters of the positive electrode active material can be selected from the above content on lithium-ion batteries, and will not be repeated here.

[0080] Another embodiment of this application provides a method for preparing a positive electrode active material, comprising the following steps: mixing a non-lithium metal hydroxide with a lithium source, and performing a first sintering in a first atmosphere including ozone; the non-lithium metal element in the non-lithium metal hydroxide includes Ni element, and the molar amount of Ni element accounts for more than 20% of the total molar amount of non-lithium metal elements in the non-lithium metal hydroxide.

[0081] In the preparation method of this embodiment, during the first sintering, the first atmosphere includes ozone. Ozone can increase the oxygen partial pressure on the surface of the material, suppress the extraction of oxygen atoms from the lattice of the material surface, increase the lattice oxygen ratio of the lithium nickel-based oxide surface, and thus promote the specific capacity of the lithium nickel-based oxide. Simultaneously, the preparation method of this embodiment can increase the lattice oxygen content of the lithium nickel-based oxide surface, enabling the lithium nickel-based oxide to maintain good structural stability. When this lithium nickel-based oxide is applied to a lithium-ion battery, it can improve the battery's cycle performance.

[0082] At the same time, because ozone has higher oxidizing power, it can shorten the first sintering time and lower the first sintering temperature.

[0083] Optionally, in non-lithium metal hydroxides, the percentage of the molar amount of Ni element to the total molar amount of non-lithium metal elements in the non-lithium metal hydroxides can be 20%, 30%, 40%, 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 92%, 95%, 98%, 99%, 100%, or any value within the range of any two of the above values.

[0084] It is understandable that a 100% percentage of the molar amount of Ni in a non-lithium metal hydroxide indicates that the non-lithium metal in the non-lithium metal hydroxide is Ni.

[0085] Optionally, the lithium source includes one or more of LiOH and Li2CO3.

[0086] In some embodiments, the volume percentage of ozone in the first atmosphere is 6% to 8%. This volume percentage of ozone in the first atmosphere, within this range, can promote an increase in the lattice oxygen content on the surface of the prepared lithium nickel-based oxide while using a relatively low amount of ozone. Optionally, the volume percentage of ozone in the first atmosphere can be 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, or any value within the range of any two of the above values.

[0087] Optionally, the first atmosphere may also include oxygen, and the volume percentage of oxygen in the first atmosphere may be 92% to 94%, for example, the volume percentage of oxygen in the first atmosphere may be 92%, 92.2%, 92.5%, 92.8%, 93%, 93.2%, 93.5%, 93.8%, 94%, and any value within the range of any two of the above values.

[0088] Optionally, the first atmosphere may further include oxygen and nitrogen, wherein the volume percentage of oxygen in the first atmosphere may be 73% to 76%, and the volume percentage of nitrogen in the first atmosphere may be 18% to 19%. More optionally, the volume percentage of oxygen in the first atmosphere may be 73%, 73.5%, 74%, 74.5%, 75%, 75.5%, 76%, or any value within the range of any two of the above values. The volume percentage of nitrogen in the first atmosphere may be 18%, 18.2%, 18.5%, 18.8%, 19%, or any value within the range of any two of the above values.

[0089] In some embodiments, the first sintering temperature is 700℃ to 1100℃. Optionally, the first sintering temperature can be 7050℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, or any value within the range of any two of the above values. Optionally, the first sintering time is 1h to 10h. More optionally, the first sintering time can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, or any value within the range of any two of the above values.

[0090] In some embodiments, prior to the first sintering, the process further includes mixing a non-lithium metal hydroxide with a lithium source and performing a second sintering in a second atmosphere, which includes oxygen. The second sintering can pre-sinter the non-lithium metal hydroxide with the lithium source, improving the effectiveness of the first sintering.

[0091] Optionally, the volume percentage of oxygen in the second atmosphere is 20% to 100%. For example, the volume percentage of oxygen in the second atmosphere can be 20%, 21%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any value within the range of any two of the above values.

[0092] Optionally, the second atmosphere may also include nitrogen, and the volume percentage of nitrogen in the second atmosphere may be less than 20%. For example, the volume percentage of nitrogen in the second atmosphere may be 1%, 5%, 10%, 15%, 20%, or any value within the range of any two of the above values.

[0093] Alternatively, the second atmosphere can be an air atmosphere or a pure oxygen atmosphere.

[0094] In some embodiments, during the preparation of lithium nickel-based oxides, a second atmosphere is added to the sintering equipment. After a second sintering, the oxygen in the second atmosphere can be partially converted into ozone by applying an electric field, thereby introducing ozone into the sintering equipment.

[0095] In some embodiments, the second sintering temperature is 400℃ to 600℃. Optionally, the second sintering temperature can be 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, or any value within the range of any two of the above values. Optionally, the second sintering time is 1h to 3h. For example, the second sintering time can be 1h, 1.2h, 1.5h, 1.8h, 2h, 2.2h, 2.5h, 2.8h, 3h, or any value within the range of any two of the above values.

[0096] In some embodiments, the process further includes, after the first sintering, a third sintering of the material after the first sintering in a third atmosphere, wherein the third atmosphere includes oxygen.

[0097] Optionally, the volume percentage of oxygen in the third atmosphere is 20% to 100%. For example, the volume percentage of oxygen in the third atmosphere can be 20%, 21%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any value within the range of any two of the above values.

[0098] Optionally, the volume percentage of oxygen in the third atmosphere is 20% to 100%. For example, the volume percentage of oxygen in the third atmosphere can be 20%, 21%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any value within the range of any two of the above values.

[0099] Optionally, the third atmosphere may also include nitrogen, and the volume percentage of nitrogen in the third atmosphere may be less than 20%. For example, the volume percentage of nitrogen in the third atmosphere may be 1%, 5%, 10%, 15%, 20%, or any value within the range of any two of the above values.

[0100] Alternatively, the third atmosphere can be an air atmosphere or a pure oxygen atmosphere.

[0101] Optionally, the gas in the second atmosphere is the same as the gas in the third atmosphere.

[0102] In some embodiments, the temperature of the third sintering is 700°C to 1100°C. Optionally, the temperature of the third sintering can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, or any value within the range of any two of the above values. Further optionally, the temperature of the third sintering is the same as the temperature of the first sintering.

[0103] In some embodiments, the third sintering time is 1 hour to 10 hours. Further optionally, the third sintering time can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or any value within the range of any two of the above values.

[0104] In some embodiments, during the preparation of lithium nickel-based oxides, a second atmosphere is added to the sintering equipment for a second sintering. After the second sintering, an electric field is applied to partially convert the oxygen in the second atmosphere into ozone, thereby introducing ozone into the sintering equipment. After the first sintering, the electric field is removed, and the second atmosphere is added again to form a third atmosphere, followed by a third sintering.

[0105] Understandably, during the preparation of lithium nickel-based oxides, after the third sintering, heating is stopped, and the lithium nickel-based oxides are allowed to cool naturally to room temperature in the sintering equipment.

[0106] In some embodiments, for example, lithium nickel-based oxides, with respect to the positive electrode active material, include those with the chemical formula Li. x (Ni a Co b Mn c ) 1- d M d O 2-y A y The material has the following properties: 0.2≤x≤1.2, 0.2≤a≤1, 0≤b≤0.1, 0≤c≤0.1, a+b+c=1, 0≤d<1, 0≤y<2, M includes one or more of Zr, Sr, B, Sn, Al, Mg, Fe, Cu, V, Ti, W, Sb, Dy and Te, and A includes one or more of N, P, S and halogen elements.

[0107] Optionally, 'a' can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.92, 0.95, 0.98, 0.99, 1, or any value within the range of any two of the above values. Further optionally, Li... x (Ni a Co b Mnc ) 1-d M d O 2-y A y It could be LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.09 Mn 0.01 O2, LiNi 0.92 Co 0.05 Mn 0.03 O2, LiNi 0.96 Co 0.02 Mn 0.02 O2, etc.

[0108] As some alternative examples of x, x can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, and any value within the range consisting of any two of the above values.

[0109] As some alternative examples of b, 0 ≤ b ≤ 0.1. Optionally, b can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, and any value within the range consisting of any two of the above values.

[0110] As some alternative examples of c, 0 ≤ c ≤ 0.1. c can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, and any value within the range of any two of the above values.

[0111] As some optional examples of d, d can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and any value within the range of any two of the above values. Optionally, 0 ≤ d ≤ 0.05.

[0112] As some optional examples of y, y can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 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 value within the range of any two of the above values. Optionally, 0 ≤ y ≤ 0.05.

[0113] It is understandable that A includes one or more of N, P, S and halogen elements, where halogen elements can be F, Cl, Br, etc.

[0114] Optionally, the positive electrode active material may also include a lithium-containing phosphate. The lithium-containing phosphate may include at least one of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon. The lithium-containing phosphate may also include one or more of lithium manganese phosphate and a composite of lithium manganese phosphate and carbon.

[0115] Further optionally, the positive electrode active material may also include one or more of the following materials: lithium cobalt oxide (such as LiCoO2), lithium manganese oxide, lithium manganese cobalt oxide, and modified compounds thereof. Non-limiting examples of lithium cobalt oxide may include LiCoO2. Non-limiting examples of lithium manganese oxide may include LiMnO2, LiMn2O4, etc.

[0116] In some embodiments, the positive electrode active layer may optionally include a binder. As a non-limiting example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0117] In some embodiments, the positive electrode active layer may optionally include a conductive agent. As a non-limiting example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0118] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be obtained by forming a metal material on the polymer material substrate. Non-limiting examples of the metal material in the positive electrode current collector may include one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limiting examples of the polymer material substrate in the positive electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0119] In some embodiments, the positive electrode sheet can be prepared by dispersing the components used to prepare the positive electrode sheet, such as the positive electrode active material, conductive agent, binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry onto at least one surface of the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing, and other processes. The solvent can be selected from, but is not limited to, any of the solvents described in the foregoing embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface of the positive electrode current collector or both surfaces of the positive electrode current collector.

[0120] In some embodiments, the lithium-ion battery further includes a negative electrode sheet. The negative electrode sheet includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector, the negative active layer comprising a negative active material.

[0121] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be obtained by forming a metal material on the polymer material substrate. Non-limiting examples of the metal material in the negative electrode current collector may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limiting examples of the polymer material substrate in the negative electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0122] In some embodiments, the negative electrode active material includes graphite. Optionally, the graphite includes one or more of artificial graphite and natural graphite. Further optionally, the negative electrode active material may also employ negative electrode active materials known in the art for use in batteries. As a non-limiting example, the negative electrode active material may include one or more of the following materials: soft carbon, hard carbon, tin-based materials, and lithium titanate, etc. Tin-based materials may include one or more of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0123] In some embodiments, the negative electrode active layer may optionally include a binder. The binder may include one or more 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).

[0124] In some embodiments, the negative electrode active layer may optionally include a conductive agent. The conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0125] In some embodiments, the negative electrode active layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0126] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder, and any other components, in a solvent (a non-limiting example of a solvent is deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto at least one surface of the negative electrode current collector, and then obtaining the negative electrode sheet after processes such as drying and cold pressing. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or both surfaces of the negative electrode current collector.

[0127] In some embodiments, the lithium-ion battery also includes an electrolyte. The electrolyte serves to conduct ions between the positive and negative electrode plates. This application does not impose any particular limitation on the type of electrolyte, which can be selected according to requirements. For example, the electrolyte can be liquid, gel, or all-solid.

[0128] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0129] In some embodiments, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0130] In some embodiments, the solvent may include 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 One or more of the following: fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0131] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0132] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), etc.

[0133] It is understood that the battery also includes a separator. The separator is located between the positive electrode and the negative electrode. This application does not impose any particular restriction on the type of separator; any well-known porous separator with good chemical and mechanical stability can be selected.

[0134] In some embodiments, the material of the separator may include one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0135] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0136] In some embodiments, the lithium-ion battery may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0137] In some embodiments, the outer packaging of the lithium-ion battery can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the lithium-ion battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0138] This application does not impose any particular limitation on the shape of the lithium-ion battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 shows a square-structured lithium-ion battery 1 as an example.

[0139] In some embodiments, referring to FIG2, the outer packaging may include a housing 11 and a cover plate 13. The housing 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be placed over the opening to close the receiving cavity. A positive electrode sheet, a negative electrode sheet, and a separator can be formed into an electrode assembly 12 by a winding process or a stacking process. The electrode assembly 12 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 12. The lithium-ion battery 1 may contain one or more electrode assemblies 12, which can be selected by those skilled in the art according to actual needs.

[0140] In some implementations, the lithium-ion battery can be a single cell, a battery module, or a battery pack.

[0141] The battery module includes at least one lithium-ion battery. The battery module may contain one or more lithium-ion batteries, and those skilled in the art can select an appropriate number based on the application and capacity of the battery module.

[0142] In a battery module, multiple lithium-ion batteries can be arranged sequentially along the length of the module. Of course, they can also be arranged in any other manner. Furthermore, these multiple lithium-ion batteries can be secured using fasteners.

[0143] Optionally, the battery module may also include a housing with a receiving space in which multiple lithium-ion batteries are housed.

[0144] In some embodiments, the battery modules can also be assembled into a battery pack, and the battery pack may contain one or more battery modules. Those skilled in the art can select an appropriate number based on the application and capacity of the battery pack.

[0145] The battery pack may include a battery box and multiple battery modules disposed within the battery box. The battery box includes an upper body and a lower body, with the upper body covering the lower body to form a closed space for accommodating the battery modules. The multiple battery modules can be arranged in any manner within the battery box.

[0146] In addition, this application also provides an electrical device, which includes the lithium-ion battery provided in this application. The battery can be used as a power source for the electrical device or as an energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Among them, mobile devices may be, for example, mobile phones, laptops, etc.; electric vehicles may be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to.

[0147] As an electrical device, lithium-ion batteries can be selected based on its usage requirements.

[0148] Figure 3 shows an example of an electrical device 2. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this electrical device, a battery pack or battery module can be used.

[0149] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can be powered by a battery.

[0150] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0151] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0152] Example 1

[0153] (1) Lithium nickel-based oxides

[0154] Take Ni 0.83Co 0.12 Mn 0.05 Using (OH)₂ as the precursor and LiOH as the lithium source, with a lithium ratio (Li molar weight: total transition metal molar weight) of 1:1.05, the mixture was uniformly placed in a tube furnace and subjected to a second sintering at 550°C for 2 hours under a pure oxygen atmosphere. The temperature was then raised to 800°C, and an electric field was applied to convert some of the pure oxygen into ozone, which comprised 7% of the atmosphere by volume. A first sintering was then performed for 1 hour. Finally, sintering continued at 800°C under a pure oxygen atmosphere for 9 hours, followed by cooling to room temperature to obtain lithium nickel-based oxide. The non-lithium metal elements in the lithium nickel-based oxide are Co and Mn.

[0155] (2) Positive electrode plate

[0156] The non-lithium metal hydroxide obtained in step (1) is used as the positive electrode active material. The positive electrode active material, conductive carbon black, and binder polyvinylidene fluoride are mixed in a weight ratio of 97:2:1, and N-methylpyrrolidone (NMP) solvent is added and stirred to prepare a positive electrode slurry. The positive electrode slurry is then coated onto the current collector aluminum foil, dried, and then cold-pressed, slit, and cut into sheets to form the positive electrode sheet.

[0157] (3) Negative electrode plate

[0158] The negative electrode active material graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and dispersant sodium carboxymethyl cellulose (CMC-Na) are mixed in a weight ratio of 97.15:0.7:0.95:1.2, and then added to deionized water as a solvent and stirred to prepare a negative electrode slurry. The negative electrode slurry is then coated onto a current collector copper foil, dried, and subjected to cold pressing, slitting, and cutting to form the negative electrode sheet.

[0159] (4) Separating membrane

[0160] Polypropylene film is used as the separator.

[0161] (5) Electrolyte

[0162] In an argon-atmospheric glove box with a water content <0.1 ppm and an oxygen content <0.1 ppm, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 3:7 to obtain an organic solvent. LiPF6 was then dissolved in the organic solvent, with a LiPF6 mass percentage relative to the electrolyte of 12.5%.

[0163] (6) Lithium-ion batteries

[0164] The positive electrode, separator, and negative electrode are prepared in sequence, with the separator positioned between the positive and negative electrodes to provide isolation, thus preparing a stacked bare cell. The bare cell is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0165] Example 2

[0166] Compared with Example 1, the difference in this example is that the first sintering time in the lithium nickel-based oxide is 5 hours.

[0167] Example 3

[0168] Compared with Example 1, the difference in this example is that the first sintering time in the lithium nickel-based oxide is 9 hours.

[0169] Example 4

[0170] The preparation method of lithium nickel-based oxide in this embodiment is different from that in Example 1.

[0171] Take Ni 0.65 Co 0.07 Mn 0.28 Using (OH)₂ as a precursor and Li₂CO₃ as the lithium source, with a lithium ratio of 1:1.05, the mixture was homogeneously placed in a tube furnace and subjected to a second sintering at 550°C for 2 hours under a pure oxygen atmosphere. The temperature was then raised to 850°C, and an electric field was applied to convert some of the pure oxygen into ozone, which comprised 7% of the atmosphere by volume. This was followed by a first sintering for 1 hour. Sintering continued at 850°C under a pure oxygen atmosphere for another 9 hours, and then the mixture was cooled to room temperature to obtain a lithium nickel-based oxide. The non-lithium metal elements in the lithium nickel-based oxide are Co and Mn.

[0172] Example 5

[0173] Compared with Example 2, the difference in this example is that the first sintering time in the lithium nickel-based oxide is 5 hours.

[0174] Example 6

[0175] Compared with Example 2, the difference in this example is that the first sintering time in the lithium nickel-based oxide is 9 hours.

[0176] Example 7

[0177] The preparation method of lithium nickel-based oxide in this embodiment is different from that in Example 1.

[0178] Take Ni 1 / 3 Co 1 / 3 Mn 1 / 3Using (OH)₂ as a precursor and Li₂CO₃ as the lithium source, with a lithium ratio of 1:1.05, the mixture was uniformly placed in a tube furnace and subjected to a second sintering at 550°C for 2 hours in an air atmosphere. The temperature was then raised to 1000°C, and an electric field was applied to convert some of the air into ozone, with ozone comprising 7% of the atmosphere by volume. A first sintering was then performed for 1 hour. Finally, sintering continued at 1000°C in an air atmosphere for 9 hours, followed by cooling to room temperature to obtain a lithium nickel-based oxide. The non-lithium metal elements in the lithium nickel-based oxide are Co and Mn.

[0179] Example 8

[0180] The difference between this embodiment and Example 7 is that the first sintering time in the lithium nickel-based oxide is 5 hours.

[0181] Example 9

[0182] Compared with Example 7, the difference in this example is that the first sintering time in the lithium nickel-based oxide is 9 hours.

[0183] Comparative Example 1

[0184] The preparation method of the lithium nickel-based oxide in this comparative example is different from that in Example 1.

[0185] Take Ni 0.83 Co 0.12 Mn 0.05 Using (OH)₂ as the precursor and LiOH as the lithium source, with a lithium ratio of 1:1.05, the mixture was uniformly placed in a tube furnace and subjected to a second sintering at 550°C under a pure oxygen atmosphere for 2 hours. The temperature was then increased to 800°C and sintered for another 10 hours, followed by cooling to room temperature to obtain lithium nickel-based oxide. The non-lithium metal elements in the lithium nickel-based oxide are Co and Mn.

[0186] The XPS Ni 2p spectrum of the lithium nickel-based oxide in Comparative Example 1 is shown in Figure 7, the O 1s spectrum is shown in Figure 8, and the XRD spectrum is shown in Figure 6. The lattice oxygen percentage and Ni content obtained from the spectra are shown in Figure 7. 3+ The proportion and I (003) / I (104) As shown in Table 1.

[0187] Comparative Example 2

[0188] The preparation method of the lithium nickel-based oxide in this comparative example is different from that in Example 4.

[0189] Take Ni 0.65 Co 0.07 Mn 0.28Using (OH)₂ as the precursor and Li₂CO₃ as the lithium source, with a lithium ratio of 1:1.05, the mixture was uniformly placed in a tube furnace and subjected to a second sintering at 550°C under a pure oxygen atmosphere for 2 hours. The temperature was then increased to 850°C and sintered for another 10 hours, followed by cooling to room temperature to obtain lithium nickel-based oxide. The non-lithium metal elements in the lithium nickel-based oxide are Co and Mn.

[0190] Comparative Example 3

[0191] The preparation method of the lithium nickel-based oxide in this comparative example is different from that in Example 7.

[0192] Take Ni 1 / 3 Co 1 / 3 Mn 1 / 3 Using (OH)2 as a precursor and Li2CO3 as a lithium source, with a lithium ratio of 1:1.05, the mixture was uniformly placed in a tube furnace and heated to 550°C for a second sintering under an air atmosphere for 2 hours. Then, the temperature was raised to 1000°C and sintered for another 10 hours. Finally, the mixture was cooled to room temperature to obtain lithium nickel-based oxide.

[0193] (1) The XPS Ni 2p spectra of the lithium nickel-based oxides in Example 1 and Comparative Example 1 are shown in Figures 4 and 7, respectively. As can be seen from Figures 4 and 7, in the lithium nickel-based oxide of Example 1, Ni... 3+ The proportion of Ni is higher than that of the control group (1). 3+ A higher proportion of lithium nickel oxide can reduce the mixing degree of Li and Ni elements, which is conducive to the full utilization of the specific capacity of lithium nickel oxide.

[0194] (2) The XPS O1s spectra of the nickel-based oxides in Example 1 and Comparative Example 1 are shown in Figures 5 and 8, respectively. As can be seen from Figures 5 and 8, the peak area ratio of the binding energy of 528eV to 530eV in Example 1 is higher than that in Comparative Example 1. This can help maintain a better crystal structure of lithium nickel-based oxides, reduce the risk of collapse and phase transition during charging and discharging, and thus improve the cycle performance of the battery.

[0195] (3) The XRD patterns of the lithium nickel-based oxides in Example 1 and Comparative Example 1 are shown in Figure 8. In Figure 8, the peak near 18° represents the diffraction peak of the (003) crystal plane, and the peak near 44° is the diffraction peak of the (104) crystal plane. As can be seen from Figure 8, the XRD patterns of the lithium nickel-based oxides in Example 1 are... (003) / I (104) I greater than that of lithium nickel-based oxide in Comparative Example 1 (003) / I (104) This indicates that the layered structure of the lithium nickel-based oxide in Example 1 has a higher degree of order and a lower degree of lithium nickel mixing, which can enable the battery to have higher cycle performance.

[0196] (4) The specific capacity of the lithium nickel-based oxides in Examples 1-9 and Comparative Examples 1-3 was tested. The test results are shown in Table 1.

[0197] Examples 1-3, Comparative Example 1: The battery was left to stand for 10 minutes, then charged at a constant current of 0.33C to 4.25V, charged at a constant voltage until the current was less than 0.05C, left to stand for 10 minutes, discharged at 0.33C to 2.8V, left to stand for 10 minutes, and repeated three times. The discharge capacity of the third discharge was taken and divided by the mass of lithium nickel-based oxide in the battery to obtain the specific capacity.

[0198] Examples 4-9 and Comparative Examples 2-3: The battery was left to stand for 10 minutes, then charged at a constant current of 0.33C to 4.4V, charged at a constant voltage until the current was less than 0.05C, left to stand for 10 minutes, discharged at 0.33C to 2.5V, left to stand for 10 minutes, and repeated three times. The discharge capacity of the third discharge was taken and divided by the mass of lithium nickel-based oxide in the battery to obtain the specific capacity.

[0199] (5) Batteries from Examples 1 to 9 and Comparative Examples 1 to 3 were subjected to a 25°C cycle test. The test results are shown in Table 1.

[0200] Examples 1-3, Comparative Example 1: The battery was left to stand for 10 minutes, then charged at a constant current of 0.33C to 4.25V, charged at a constant voltage until the current was less than 0.05C, left to stand for 10 minutes, and then discharged at a constant current of 1C to 2.8V. This constitutes one charge-discharge cycle. The battery capacity retention rate was tested after 1000 cycles at 25℃. The capacity retention rate (%) after 1000 cycles = (discharge capacity of the 1000th cycle / discharge capacity of the first cycle) × 100%.

[0201] Examples 4-6, Comparative Example 2: The battery was left to stand for 10 minutes, then charged at a constant current of 0.33C to 4.4V, charged at a constant voltage until the current was less than 0.05C, left to stand for 10 minutes, and then discharged at a constant current of 1C to 2.5V. This constitutes one charge-discharge cycle. After 700 cycles, the battery capacity retention rate was tested. The capacity retention rate (%) after 700 cycles at 25℃ = (discharge capacity of the 700th cycle / discharge capacity of the first cycle) × 100%.

[0202] Examples 7-9, Comparative Example 3: The battery was left to stand for 10 minutes, then charged at a constant current of 0.33C to 4.4V, charged at a constant voltage until the current was less than 0.05C, left to stand for 10 minutes, and then discharged at a constant current of 1C to 2.5V. This constitutes one charge-discharge cycle. After 600 cycles, the battery capacity retention rate was tested. The capacity retention rate (%) of the battery after 600 cycles at 25°C = (discharge capacity of the 600th cycle / discharge capacity of the first cycle) × 100%.

[0203] (6) Batteries from Examples 1-9 and Comparative Examples 1-3 were subjected to a 60°C storage test. The test results are shown in Table 1.

[0204] Examples 1-3, Comparative Example 1: A fully charged battery was stored at 60°C for 80 days, and the capacity retention rate of the battery after storage was tested.

[0205] Examples 4-6, Comparative Example 2: A fully charged battery was stored at 60°C for 63 days, and the capacity retention rate of the battery after storage was tested.

[0206] Examples 7-9 and Comparative Example 3: A fully charged battery was stored at 60°C for 60 days, and the capacity retention rate of the battery after storage was tested.

[0207] Table 1

[0208] In Table 1, the Ni content represents the percentage of the molar amount of Ni element in the total molar amount of non-lithium metal elements in lithium nickel-based oxides. The specific capacity is expressed in mAh / g. The peak area percentage of 528 eV–530 eV represents the percentage of the peak area with a binding energy of 528 eV–530 eV in the O1s spectrum of the lithium nickel-based oxides obtained from X-ray photoelectron spectroscopy. 3+ The percentage indicates the proportion of Ni in lithium nickel-based oxides. 3+ The percentage of Ni atoms present in the form of Ni in the total Ni atoms in lithium nickel-based oxides.

[0209] As can be seen from Table 1, when the nickel content in the lithium nickel-based oxide is the same, the battery in the example has a higher cycle retention rate at 25°C and a storage retention rate at 60°C.

[0210] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0211] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A lithium-ion battery, comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive active layer located on at least one surface of the positive current collector, the positive active material of the positive active layer comprising a lithium nickel-based oxide, the lithium nickel-based oxide comprising Li and non-lithium metal elements; the non-lithium metal elements comprising Ni, the molar amount of Ni accounting for more than 20% of the total molar amount of the non-lithium metal elements, and the peak area with a binding energy of 528 eV to 530 eV accounting for 12% to 40% in the O1s spectrum of the lithium nickel-based oxide as measured by X-ray photoelectron spectroscopy.

2. The lithium-ion battery of claim 1, wherein, In the fully discharged state of the lithium-ion battery, the oxygen vacancy ratio of the lithium nickel-based oxide is m, the total molar amount of non-oxygen elements in the lithium nickel-based oxide is n1, the molar amount of oxygen elements in the lithium nickel-based oxide is n2, m = (n1-n2) / n1×100%, and m is less than or equal to 2%.

3. The lithium-ion battery of any one of claims 1-2, wherein, In the fully discharged state of the lithium-ion battery, the XRD pattern of the lithium nickel-based oxide includes diffraction peaks of the (003) crystal plane and diffraction peaks of the (104) crystal plane, and the intensity of the diffraction peak of the (003) crystal plane is I. (003) The intensity of the diffraction peak of the (104) crystal plane is I. (104) , where I (003) / I (104) It ranges from 1.2 to 1.

4.

4. The lithium-ion battery according to any one of claims 1 to 3, wherein, The percentage of the molar amount of Ni element in the total molar amount of the non-lithium metal elements is greater than or equal to 20% and less than 50%, and the peak area with a binding energy of 528 eV to 530 eV accounts for 25% to 40% in the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy.

5. The lithium-ion battery of claim 4, wherein, In the full discharge state of the lithium ion battery, the proportion of Ni 3+ in the Ni element of the lithium nickel-based oxide is less than or equal to 35%.

6. The lithium-ion battery of any one of claims 1-3, wherein, The percentage of the molar amount of Ni element in the total molar amount of the non-lithium metal elements is greater than or equal to 50% and less than 80%, and the peak area with a binding energy of 528 eV to 530 eV accounts for 25% to 40% in the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy.

7. The lithium-ion battery of claim 6, wherein, In the fully discharged state of the lithium-ion battery, the Ni element in the lithium nickel-based oxide contains Ni. 3+ The proportion ranges from 30% to 87.5%.

8. The lithium-ion battery of any one of claims 1-3, wherein, The molar amount of Ni element accounts for a percentage of the total molar amount of the non-lithium metal elements that is greater than or equal to 80% and less than or equal to 100%, and the peak area with a binding energy of 528 eV to 530 eV accounts for 10% to 25% of the O1s spectrum of the lithium nickel-based oxide measured by X-ray photoelectron spectroscopy.

9. The lithium-ion battery of claim 8, wherein, In the full discharge state of the lithium ion battery, the proportion of Ni 3+ in the Ni element of the lithium nickel-based oxide is 77.5% to 100%.

10. A positive electrode active material comprising a lithium nickel-based oxide, wherein the lithium nickel-based oxide contains Li and non-lithium metal elements; wherein the non-lithium metal elements include Ni, wherein the molar amount of Ni accounts for more than 20% of the total molar amount of the non-lithium metal elements, and wherein the peak area with a binding energy of 528 eV to 530 eV accounts for 12% to 40% of the O1s spectrum of the lithium nickel-based oxide as measured by X-ray photoelectron spectroscopy.

11. A method for preparing a positive electrode active material, comprising the following steps: A non-lithium metal hydroxide is mixed with a lithium source and subjected to a first sintering in a first atmosphere including ozone; the non-lithium metal element in the non-lithium metal hydroxide includes Ni element, and the molar amount of Ni element accounts for more than 20% of the total molar amount of non-lithium metal elements in the non-lithium metal hydroxide.

12. The method of producing a positive electrode active material according to claim 11, wherein The ozone in the first atmosphere has a volume percentage of 6% to 8%.

13. The method of producing a positive electrode active material according to any one of claims 11 to 12, wherein The first sintering satisfies one or more of the following characteristics: (1) The temperature of the first sintering is 700℃~1100℃; (2) The first sintering time is 1h to 10h.

14. The method of producing a positive electrode active material according to any one of claims 11 to 13, wherein The process before the first sintering also includes: The non-lithium metal hydroxide is mixed with the lithium source, and a second sintering is performed in a second atmosphere, the second atmosphere including oxygen.

15. The method of producing a positive electrode active material according to any one of claims 11 to 14, wherein The second sintering satisfies one or more of the following characteristics: (1) The second sintering temperature is 400℃~600℃; (2) The second sintering time is 1h to 3h.

16. The method of producing a positive electrode active material according to any one of claims 11 to 15, wherein The process after the first sintering also includes: The material after the first sintering is subjected to a third sintering in a third atmosphere, which includes oxygen.

17. The method of producing a positive electrode active material according to claim 16, wherein The third sintering satisfies one or more of the following characteristics: (1) The temperature of the third sintering is 700℃~1100℃; (2) The third sintering time is 1h to 10h.

18. An electrical device comprising a lithium-ion battery according to any one of claims 1 to 9.

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