Lithium-ion secondary battery, positive electrode active material, production method, and electric device

Abstract

This application relates to the field of battery technology, and in particular to lithium-ion secondary batteries, positive electrode active materials, preparation methods, and electrical devices. The lithium-ion secondary battery includes lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, and its crystal structure includes a spinel-type structure; it includes Li b A a Ni 0.5‑x‑g Mn 1.5‑y‑t M x+y G g T t O 4‑k‑q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is a non-nickel-manganese trivalent metal element with an ionic radius ranging from 33 pm to 90 pm; G includes +1 valent metal elements and / or +2 valent metal elements; T includes one or more of +4, +5, and +6 valent elements; Q includes one or more of F, Cl, Br, I, S, and N; 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5; where x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, and -0.03 ≤ x - y ≤ 0.03. This can reduce Mn dissolution and improve the cycle stability and lifespan of the battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to lithium-ion secondary batteries, positive electrode active materials, preparation methods and electrical equipment. Background Technology

[0002] With the development of modern technology, lithium-ion batteries are considered the preferred choice for green and environmentally friendly batteries due to their advantages such as high energy density, long cycle life, and good environmental performance. Lithium-ion batteries can be widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in electric vehicles, power tools, military equipment, and aerospace. Among them, lithium spinel nickel manganese oxide (LNMO) is a high-voltage cathode material (voltage plateau around 4.7V), but its cycle capacity decays rapidly. Improving the cycle performance of lithium spinel nickel manganese oxide is a technical problem that urgently needs to be solved. Summary of the Invention

[0003] In view of this, this application mainly provides lithium-ion secondary batteries, positive electrode active materials, preparation methods and electrical equipment, so as to reduce the manganese leaching of the positive electrode sheet and improve the structural stability of the positive electrode active material, thereby improving the cycle stability of lithium-ion secondary batteries.

[0004] To solve the aforementioned technical problems, the first aspect of this application is as follows: a lithium-ion secondary battery, comprising a positive electrode, a negative electrode, and an electrolyte; the positive electrode includes a positive active material layer, the positive active material layer includes a positive active material, the positive active material includes lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, and the crystal structure of the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes a spinel structure; the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Li b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k-q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is a non-nickel-manganese trivalent metal element with an ionic radius ranging from 33 pm to 90 pm; G includes a +1 valent metal element and / or a +2 valent metal element; T includes one or more of +4, +5, and +6 valent elements; Q includes one or more of F, Cl, Br, I, S, and N; 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5; where x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, and -0.03 ≤ xy ≤ 0.03.

[0005] In this embodiment, the spinel-type lithium nickel manganese oxide is less prone to phase transition and exhibits relatively high stability. Lithium nickel manganese oxides containing non-nickel-manganese trivalent metal elements include Li... b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k-q Q q By employing a non-nickel-manganese trivalent metal element M with an ionic radius of 33 pm to 90 pm to dope spinel-structured lithium nickel-manganese oxide, the structural stability can be improved by using M as a dopant. This is because the ionic radius of M is comparable to that of nickel and manganese ions, and it can maintain valence equilibrium (i.e., when a non-nickel-manganese trivalent metal element is doped into spinel-structured lithium nickel-manganese oxide, the valence of nickel and manganese in the spinel structure remains unchanged or almost unchanged). Furthermore, it can be mixed with Ni and Mn elements, thus enhancing structural stability. Simultaneously, by controlling the doping amount of M, and ensuring that 0 < x ≤ 0.2, 0 < y ≤ 0.2, and the difference between x and y does not exceed 0.03, without increasing Mn... 3+ Maintaining chemical valence balance while taking into account Mn content 3+ Low content reduces Mn leaching, minimizes Mn deposition on the negative electrode and its damaging effect on the SEI film, improves the cycle stability and cycle life of lithium-ion secondary batteries; A element doping allows it to enter the Li sites in the crystal structure; G, being a +1 and / or +2 valence metal element, increases the Mn valence state and reduces Mn content after doping into Ni and Mn sites due to its low valence state. 3+ By doping with T elements of +4, +5, and +6 valence, the high valence of T elements forms strong bonds with O, stabilizing the structure. Q is a strongly electronegative element, which is doped into the O site and forms strong bonds with Ni, Mn, and M, stabilizing the structure. The synergistic effect of elements such as A, M, G, T, and Q forms a specific chemical formula structure.

[0006] In any embodiment, M includes one or more of Al, Sc, Cr, Fe, Co, Ga, Y, Nb, Ru, Rh, In, Ho, Er, Tm, Yb, Lu, and Os.

[0007] In the embodiments of this application, the ionic radius of the aforementioned non-nickel manganese trivalent metal element M is related to that of Mn. 4+ Mn 3+ Ni 3+ Ni 2+ It can approximate and maintain valence equilibrium. By doping non-nickel manganese trivalent metal element M into the Ni and Mn sites of the spinel structure, it can simultaneously mix with Ni and Mn elements, which can improve the structural stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements.

[0008] In any embodiment, the ionic radius of M ranges from 53 pm to 70 pm.

[0009] In this embodiment, the ionic radius of the non-nickel-manganese trivalent metal element M ranges from 53 pm to 70 pm, a range similar to that of Ni. 3+ and Mn 3+ The ionic radius is approximately the same as that of the ions, which can effectively enter the Ni and Mn lattice sites in the crystal structure, reducing lattice distortion, improving the stability of the crystal structure, and enhancing the uniformity of the content of non-nickel manganese trivalent metal elements M at doped Ni and Mn sites. Simultaneously, it can also make Mn... 3+ Reducing and maintaining manganese levels within a certain range helps to reduce manganese leaching. This improves battery cycle life through a dual mechanism of enhancing the structural stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements and reducing Mn leaching.

[0010] In any embodiment, M includes one or more of Sc, Cr, Fe, Co, Ga, and Rh.

[0011] In the embodiments of this application, the aforementioned non-nickel-manganese trivalent metal element M and Ni 3+ and Mn 3+ The ionic radii are more similar, making it easier for the Mn elements to enter the Ni and Mn sites in the crystal structure, reducing lattice distortion and improving the stability of the crystal structure. This also enhances the uniformity of the content of non-nickel manganese trivalent metal elements doped at Ni and Mn sites. This can be achieved by controlling the doping amount of M element, ensuring 0 < x ≤ 0.2, 0 < y ≤ 0.2, and the difference between x and y does not exceed 0.03, without increasing the Mn content. 3+ Maintaining chemical valence balance while taking into account Mn content 3+ The low content helps reduce manganese leaching, thereby improving battery cycle life through a dual mechanism of enhancing the structural stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements and reducing Mn leaching.

[0012] In any embodiment, when the positive electrode is in a fully discharged state, the active Mn in the positive electrode... 3+ The molar ratio with active lithium is 0~8%.

[0013] In this embodiment of the application, under the fully discharged state, the active Mn in the positive electrode is controlled... 3+ The molar ratio with active lithium is 0~8%, which makes the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements more stable, reduces the amount of Mn leaching, reduces the amount of Mn elemental deposition on the negative electrode, reduces the degree of damage to the solid electrolyte interphase (SEI) film of the negative electrode, and improves the cycle stability of lithium-ion secondary batteries.

[0014] In any embodiment, when the positive electrode is in a fully discharged state, the active Mn in the positive electrode... 3+The molar ratio with active lithium is 0~5%.

[0015] In this embodiment, under full discharge, by controlling the molar ratio of active Mn3+ to active lithium in the positive electrode to be 0~5%, the stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements is improved, the amount of Mn leaching is reduced, the amount of Mn elemental deposited on the negative electrode is reduced, the degree of damage to the solid electrolyte interphase (SEI) film of the negative electrode is reduced, and the cycle stability of the lithium-ion secondary battery is improved.

[0016] In any implementation, -0.03≤(x+g)-(y+t)≤0.03, 0<x+g≤0.25.

[0017] In the embodiments of this application, the co-doping of M, G, and T elements conforms to the principle that the subscripts x+g and y+t in the chemical formula are equal or nearly equal, which can effectively control Mn. 3+ By controlling the content of M and G elements to maintain chemical valence balance, the structural stability of the positive electrode active material is improved, and the amount of Mn dissolved is reduced, thereby improving the cycle stability and cycle life of lithium-ion secondary batteries. This is achieved by controlling the range of x+g and the doping amounts of M and G elements, thus maintaining valence balance without increasing Mn content. 3+ The content of Mn is beneficial for controlling Mn content. 3+ The content of [unspecified element] is within a favorable range. By controlling the range of g within the above range, low-valent manganese (Mn) can be suppressed by doping with low-valent elements (+1 valent metal elements and / or +2 valent metal elements). 2+ The formation of ) can reduce manganese leaching while maintaining energy density, resulting in a better energy density for lithium-ion secondary batteries. By controlling the range of t within the above range, the oxygen in lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements can be stabilized by controlling the doping amount of high-valence elements (+4, +5, +6 valence elements), thereby improving the stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements.

[0018] In any embodiment, G comprises a +2 valence metal element with an ionic radius of 49 pm to 89 pm. In the embodiments of this application, the ionic radius of element G is in the range of 49 pm to 89 pm, such that element G reacts with Ni... 2+ The approximate ionic radius of G allows it to better enter the crystal structure and mix with Ni, which can improve the structural stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, thereby improving the structural stability of lithium-ion secondary batteries.

[0019] In any embodiment, T includes +4, +5, and +6 valent metal elements with ionic radii of 33 pm to 73 pm. In the embodiments of this application, the ionic radius of element T is between 33 pm and 73 pm, such that element T reacts with Mn. 4+Its ionic radius is similar to that of Mn, so it can easily enter the crystal structure and form mixed arrangement with Mn, which can improve the stability of the crystal structure.

[0020] In any embodiment, 0 < y + t ≤ 0.2. In the embodiments of this application, by controlling the range of y + t within the above range, the content of Mn element in the crystal structure is relatively high, which can stabilize the spinel structural framework.

[0021] In any embodiment, G includes one or more of Mg, Cu, and Zn. In the embodiments of this application, Mg, Cu, and Zn are more likely to enter the crystal structure and mix with Ni to improve the structural stability of the positive electrode active material.

[0022] In any embodiment, T includes one or more of Si, P, Ti, V, Ge, As, Se, Zr, Nb, Mo, Sn, Sb, Te, Ta, and W. In the embodiments of this application, Si 4+ P 5+ Ti 4+ V 5+ 、Ge 4+ As 5+ Se 6+ Zr 4+ 、Nb 5+ Mo 6+ Sn 4+ Ta 5 + Sb 5+ W 6+ Te 4+ These elements can enter the crystal structure and form strong bonds with oxygen, improving the stability of lithium nickel manganese oxides containing non-nickel manganese trivalent metal elements; additionally, Nb 5+ Mo 6+ Sn 4+ Ta 5+ Sb 5+ W 6+ Te 4+ The larger plasma radius can increase the lattice spacing and reduce Li + Migration energy barrier, improving rate performance.

[0023] In any embodiment, 0 < y + t ≤ 0.1. In the embodiments of this application, y + t is within the above range, which results in a higher Mn content in the crystal structure of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, thus increasing the stability of the spinel structural framework and the overall stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements.

[0024] In any embodiment, 0.01 ≤ x ≤ 0.1. In the embodiments of this application, x is within the above range. By doping with an appropriate amount of non-nickel manganese trivalent metal M, the stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements can be improved, while the activity of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements can be taken into account, so that it has a higher energy density.

[0025] In any embodiment, the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Mn. 3+ Mn 3+ The proportion IM of Mn to the total Mn satisfies 0 ≤ IM ≤ 5%. In the embodiments of this application, Mn is controlled... 3+ When the proportion of Mn to total Mn is within the above range, the amount of Mn dissolved is relatively small, which can reduce the amount of Mn deposited on the negative electrode, reduce the damage of Mn dissolution to the SEI film, improve the cycle stability of lithium-ion secondary batteries, and increase cycle life.

[0026] In any implementation, 0 ≤ IM ≤ 3%. In this application's implementation, Mn is controlled... 3+ The proportion of Mn to the total Mn is within the above range. 3+ The content of Mn is relatively small. At the same time, by doping with non-nickel manganese trivalent metal elements, the structural stability of the positive electrode active material can be improved. Meanwhile, the amount of Mn leaching is small, which can reduce the amount of Mn deposited on the negative electrode, reduce the damage of Mn leaching to the SEI film, improve the cycle stability of lithium-ion secondary batteries, and improve cycle life.

[0027] In any embodiment, the lithium-ion secondary battery includes a manganese scavenger coated and / or attached to the surface of particles containing lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements; and / or the manganese scavenger is located on the surface of the positive electrode active material layer; and / or on the surface of the separator; and / or the manganese scavenger is located on the surface of the negative electrode active material layer of the negative electrode sheet.

[0028] In this embodiment, the manganese scavenger can interact with manganese ions through chemical absorption or physical adsorption, effectively capturing manganese ions dissolved from lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements. This reduces manganese deposition on the negative electrode surface, minimizes damage to the solid electrolyte interphase (SEI) film on the negative electrode surface, and lowers lithium consumption during battery cycling. The manganese scavenger can coat the surface of lithium nickel manganese oxide particles containing non-nickel manganese trivalent metal elements to form a protective layer, directly adsorbing manganese ions dissolved from these particles. This shortens the path for capturing manganese ions and improves the capture efficiency. Alternatively, the manganese scavenger can be dispersed in the positive electrode active material layer and adhered to the surface of lithium nickel manganese oxide particles containing non-nickel manganese trivalent metal elements, also adsorbing manganese ions dissolved from these particles and reducing the amount of manganese ions reaching the negative electrode surface. Manganese scavengers can be placed on the surface of the positive electrode active material layer, the separator surface, or the negative electrode active material layer. All of these can reduce the amount of manganese ions reaching the surface of the negative electrode active material layer, reduce the damage of manganese ions to the solid electrolyte interphase (SEI) film, and improve the cycle stability of lithium-ion secondary batteries.

[0029] In any embodiment, the manganese scavenger includes one or more of the following: substances containing polyoxoanionic groups, lithium-rich substances, and adsorbent substances, wherein the specific surface area of ​​the adsorbent substance is greater than or equal to 100. 2 / g, and less than or equal to 3000m 2 / g. In the embodiments of this application, substances containing polyoxoanion groups have a strong attraction to positive charges, and can exert a strong electrostatic attraction on manganese ions, anchoring or capturing manganese ions on the manganese scavenger, reducing the amount of manganese reaching the negative electrode. Lithium-rich substances readily undergo Li-Mn exchange with manganese ions, capturing Mn and releasing Li, which is beneficial for reducing the amount of manganese reaching the negative electrode. Adsorbent substances can physically adsorb manganese ions, reducing the amount of manganese reaching the negative electrode. Therefore, substances containing polyoxoanion groups, lithium-rich substances, and adsorbent substances can all reduce the damage of manganese ions to the solid electrolyte interphase (SEI) film, improving the cycle stability of lithium-ion secondary batteries.

[0030] In any embodiment, the multi-oxygen anion group material includes one or more of lithium phosphate, lithium hydrogen phosphate, lithium dihydrogen phosphate, lithium silicate, lithium sulfate, lithium polyacrylate, and lithium carbonate. In the embodiments of this application, lithium phosphate, lithium hydrogen phosphate, lithium dihydrogen phosphate, lithium silicate, lithium sulfate, lithium polyacrylate, and lithium carbonate all have a strong attraction to positive charges, and can have a strong electrostatic attraction to manganese ions, anchoring or capturing manganese ions on the manganese scavenger, reducing the amount of manganese reaching the negative electrode, and improving the cycle stability of the lithium-ion secondary battery.

[0031] In any embodiment, the lithium-rich material includes one or more of LiNiO2, Li5FeO4, Li2MnO3, Li6CoO4, Li2CuO2, Li2MoO2, Li5ReO6, Li2O, Li2O2, and Li2S. In the embodiments of this application, the aforementioned lithium-rich material can undergo Li-Mn exchange with manganese ions to capture Mn and release Li, which helps reduce the amount of manganese reaching the negative electrode. The adsorbent material can physically adsorb manganese ions, reducing the amount of manganese reaching the negative electrode and improving the cycle stability of the lithium-ion secondary battery.

[0032] In any embodiment, the adsorbent material includes one or more of activated carbon, carbon nanotubes, and zeolite. In the embodiments of this application, the above-mentioned adsorbent material can physically adsorb manganese ions, reduce the amount of manganese reaching the negative electrode, and improve the cycle stability of the lithium-ion secondary battery.

[0033] The second aspect of this application also includes a positive electrode active material, which is the same as the positive electrode active material in the lithium-ion secondary battery of the first aspect. Specifically, the positive electrode active material includes a lithium nickel manganese oxide containing a non-nickel manganese trivalent metal element, and the crystal structure of the lithium nickel manganese oxide containing the non-nickel manganese trivalent metal element includes a spinel structure; the lithium nickel manganese oxide containing the non-nickel manganese trivalent metal element includes Li b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k-q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is a non-nickel-manganese trivalent metal element with an ionic radius ranging from 33 pm to 90 pm; G includes a +1 valent metal element and / or a +2 valent metal element; T includes one or more of +4, +5, and +6 valent elements; Q includes one or more of F, Cl, Br, I, S, and N; 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5; where x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, and -0.03 ≤ xy ≤ 0.03.

[0034] In this embodiment, the spinel-type lithium nickel manganese oxide is less prone to phase transition and exhibits relatively high stability. Lithium nickel manganese oxides containing non-nickel-manganese trivalent metal elements include Li... b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T tO 4-k-q Q q By employing a non-nickel-manganese trivalent metal element M with an ionic radius of 33 pm to 90 pm to dope spinel-structured lithium nickel manganese oxide, the structural stability can be improved by using M to dope spinel-structured lithium nickel manganese oxide. Since the ionic radius of M is comparable to that of nickel and manganese ions, and it can maintain valence equilibrium (i.e., when a non-nickel-manganese trivalent metal element is doped into spinel-structured lithium nickel manganese oxide, the valence of nickel and manganese elements in the spinel structure remains unchanged or almost unchanged), it can be mixed with Ni and Mn elements. Simultaneously, by controlling the doping amount of M element x and y within the range of 0.01 to 0.2, and the difference between x and y not exceeding 0.03, without increasing Mn... 3+ Maintaining chemical valence balance while taking into account Mn content 3 + Low content reduces the amount of Mn leaching from the positive electrode active material; A element doping can enter the Li sites in the crystal structure; G is a +1 and / or +2 valence metal element, and after doping into Ni and Mn sites, its low valence state increases the valence state of Mn, thus reducing Mn content. 3+ By doping with T elements of +4, +5, and +6 valence, the high valence of T elements forms strong bonds with O, stabilizing the structure. Q is a strongly electronegative element, which is doped into the O site and forms strong bonds with Ni, Mn, and M, stabilizing the structure. The synergistic effect of elements such as A, M, G, T, and Q forms a specific chemical formula structure.

[0035] The third aspect of this application also includes a method for preparing a positive electrode active material, comprising:

[0036] Lithium salt, nickel source, manganese source and dopant source are mixed and calcined at a first temperature for a first time to form an intermediate product. The first temperature is 600℃~1200℃ and the first time is 1h~50h. The dopant source includes a non-nickel manganese trivalent metal source, or the dopant source includes a non-nickel manganese trivalent metal source and also includes one or more of A source, G source, T source and Q source. The A source includes one or more of Na source, K source, Rb source and Cs source. The G source includes a +1 valence metal source and / or a +2 valence metal source. The T source includes raw materials containing +4, +5 and +6 valence elements. The Q source includes one or more of F source, Cl source, Br source, I source, S source and N source.

[0037] The intermediate product is kept at a second temperature for a second time to form a positive electrode active material. The second temperature is 500℃~850℃, and the second time is 1h~50h. The positive electrode active material includes lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements. The crystal structure of the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes a spinel structure. The lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Li... b A a Ni 0.5-x-g Mn 1.5-y-tM x+y G g T t O 4-k-q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is a non-nickel-manganese trivalent metal element with an ionic radius ranging from 33 pm to 90 pm; G includes a +1 valent metal element and / or a +2 valent metal element; T includes one or more of +4, +5, and +6 valent elements; Q includes one or more of F, Cl, Br, I, S, and N; 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5; where x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, and -0.03 ≤ xy ≤ 0.03.

[0038] The preparation method of this application, after obtaining a lithium nickel manganese oxide intermediate product doped with non-nickel manganese trivalent metal elements, further calcines it at a second temperature for a certain time to control the mixing of M element and nickel manganese, thereby controlling the Mn content in the intermediate product. 3+ When the element content is within an optimal range, the final product is obtained.

[0039] This application provides a fourth aspect of an electrical device, comprising a lithium-ion secondary battery as described in the first aspect, and / or a positive electrode active material as described in the second aspect, and / or a positive electrode active material prepared by the preparation method of the third aspect. The electrical device according to the embodiments of this application has the same advantages as the lithium-ion secondary battery of the first aspect, and / or the same advantages as the positive electrode active material of the second aspect, and / or the same advantages as the positive electrode active material prepared by the preparation method of the third aspect. Attached Figure Description

[0040] Figure 1 This is a structural schematic diagram of a vehicle according to one embodiment of this application.

[0041] Figure 2 This is an exploded structural diagram of a battery according to one embodiment of this application.

[0042] Figure 3 This is an exploded structural diagram of a battery cell according to one embodiment of this application. Detailed Implementation

[0043] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery, and electrical device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0044] The "range" disclosed in this application is defined by 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 a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; 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 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 "ab" 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 "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

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

[0047] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means 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.

[0048] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0049] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0050] Unless otherwise specified, the unit of temperature in this application is Celsius (°C).

[0051] In lithium-ion secondary batteries, spinel lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 During the charging and discharging process, Mn (O4) 2+ Mn 3+ It is easily soluble, and Mn elemental dissolves on the negative electrode, consuming the SEI film on the negative electrode, which leads to increased Li consumption on the negative electrode and reduced cycle stability of the lithium-ion secondary battery.

[0052] Therefore, this application provides a lithium-ion secondary battery, including a positive electrode, a negative electrode, and an electrolyte; the positive electrode includes a positive active material layer, the positive active material layer includes a positive active material, the positive active material includes a lithium nickel manganese oxide containing a non-nickel manganese trivalent metal element, and the crystal structure of the lithium nickel manganese oxide containing the non-nickel manganese trivalent metal element includes a spinel structure; the lithium nickel manganese oxide containing the non-nickel manganese trivalent metal element includes Li b A a Ni 0.5-x-g Mn 1.5-y- t M x+y G g T t O 4-k-q Q qWherein, A includes one or more of Na, K, Rb, and Cs; M is a non-nickel-manganese trivalent metal element with an ionic radius ranging from 33 pm to 90 pm; G includes a +1 valent metal element and / or a +2 valent metal element; T includes one or more of +4, +5, and +6 valent elements; Q includes one or more of F, Cl, Br, I, S, and N; 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5; where x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, and -0.03 ≤ xy ≤ 0.03.

[0053] In this embodiment, the lithium nickel manganese oxide comprises a spinel-type structure, with O forming an octahedral framework. The octahedra are edge-to-edge connected, forming tetrahedral interstices. Mn and Ni occupy 1 / 2 of the oxygen octahedral interstices (16d, or 4b and 12d), and Li occupies 1 / 8 of the tetrahedral interstices (8a). The stoichiometric ratio of LiNi... 0.5 Mn 1.5 O4 mainly has two structures: an ordered structure where Ni and Mn are completely arranged in a specific order, and a disordered structure where Ni and Mn are arranged in a random order. In the ordered structure, all Ni has a +2 valence and all Mn has a +4 valence; in the disordered structure, equal amounts of Ni are present. 3+ and Mn 3+ Disordered structures exhibit higher stability. In highly ordered structures, although all Mn atoms are +4 valence, theoretically Mn... 4+ The inventors discovered that, during charging and discharging, the highly ordered spinel-type lithium nickel manganese oxide (Mn) exhibits significant dissolution. This is because, during charging and discharging, the ordered structure readily transforms into a disordered structure, undergoing a phase transition reaction. During this phase transition, Mn ions at the phase interface readily dissolve along with the Li... + The process of extraction and release results in significant dissolution of highly ordered spinel-type lithium nickel manganese oxide (Mn).

[0054] In this embodiment, the spinel-type lithium nickel manganese oxide is less prone to phase transition and exhibits relatively high stability. Lithium nickel manganese oxides containing non-nickel-manganese trivalent metal elements include Li... b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k-q Q qBy employing a non-nickel-manganese trivalent metal element M with an ionic radius of 33 pm to 90 pm to dope spinel-structured lithium nickel-manganese oxide, the structural stability can be improved by using M as a dopant. This is because the ionic radius of M is comparable to that of nickel and manganese ions, and it can maintain valence equilibrium (i.e., when a non-nickel-manganese trivalent metal element is doped into spinel-structured lithium nickel-manganese oxide, the valence of nickel and manganese in the spinel structure remains unchanged or almost unchanged). Furthermore, it can be mixed with Ni and Mn elements, thus enhancing structural stability. Simultaneously, by controlling the doping amount of M, and ensuring that 0 < x ≤ 0.2, 0 < y ≤ 0.2, and the difference between x and y does not exceed 0.03, without increasing Mn... 3+ Maintaining chemical valence balance while taking into account Mn content 3+ Low content reduces Mn leaching, minimizes Mn deposition on the negative electrode and its damaging effect on the SEI film, improves the cycle stability and cycle life of lithium-ion secondary batteries; A element doping allows it to enter the Li sites in the crystal structure; G, being a +1 and / or +2 valence metal element, increases the Mn valence state and reduces Mn content after doping into Ni and Mn sites due to its low valence state. 3+By doping with +4, +5, and +6 valence elements (T elements, with their high valence, form strong bonds with O, stabilizing the structure), and with Q elements (a highly electronegative element, doped into the O site, forming strong bonds with Ni, Mn, and M, stabilizing the structure), the synergistic effect of elements such as A, M, G, T, and Q forms a specific chemical formula structure. The ionic radius of the non-nickel-manganese trivalent metal element M can range from 33 pm, 40 pm, 50 pm, 56 pm, 60 pm, 65 pm, 70 pm, 76 pm, 80 pm, 83 pm, 90 pm, or any combination of these values, such as 33 pm~56 pm, 56 pm~76 pm, 76 pm~90 pm, etc. g can be 0, 0.01, 0.03, 0.05, 0.06, 0.08, 0.1, etc., or a range of any two of the above values, such as 0~0.01, 0.01~0.06, 0.06~0.1, etc. t can be 0, 0.01, 0.03, 0.05, 0.07, 0.08, 0.1, etc., or a range of any two of the above values, such as 0~0.03, 0.03~0.07, 0.07~0.1, etc. k can be -0.1, -0.05, 0, 0.05, 0.1, 0.2, 0.3, etc., or a range of any two of the above values, such as -0.1~0, 0~0.05, 0.05~0.3, etc. q can be 0, 0.05, 0.1, 0.13, 0.2, 0.3, 0.5, etc., or a range of any two of the above values, such as 0~0.13, 0.13~0.3, 0.3~0.5, etc. x can be 0.01, 0.04, 0.05, 0.1, 0.13, 0.16, 0.2, etc., or a range of any two of the above values, such as 0.01~0.05, 0.05~0.13, 0.13~0.2, etc. y can be 0.01, 0.04, 0.05, 0.08, 0.1, 0.13, 0.16, 0.18, 0.2, etc., or a range of any two of the above values, such as 0.01~0.08, 0.08~0.16, 0.16~0.2, etc. xy can be -0.03, -0.02, -0.01, 0, 0.01, 0.02, 0.03, etc., or a range of any two of the above values, such as -0.03 to -0.01, -0.01 to 0, 0 to 0.03, etc.

[0055] In this embodiment of the application, the non-nickel manganese trivalent metal element is a trivalent metal element that is neither nickel nor manganese.

[0056] In the embodiments of this application, it is understood that G is different from A, and G is not a divalent metal element such as Ni or Mn. T also does not include Mn element with a +4 valence.

[0057] In this embodiment, the chemical formula of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements can be obtained by inductively coupled plasma atomic emission spectrometry (ICP); the crystal structure type and the positional distribution of the elements in the crystal structure of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements can be obtained by X-ray powder diffraction (XRD).

[0058] In some implementations, M includes one or more of Al, Sc, Cr, Fe, Co, Ga, Y, Nb, Ru, Rh, In, Ho, Er, Tm, Yb, Lu, and Os.

[0059] In the embodiments of this application, the ionic radius of the aforementioned non-nickel manganese trivalent metal element M is related to that of Mn. 4+ Mn 3+ Ni 3+ Ni 2+ It can approximate and maintain valence equilibrium. By doping non-nickel manganese trivalent metal element M into the Ni and Mn sites of the spinel structure, it can simultaneously mix with Ni and Mn elements, which can improve the structural stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements.

[0060] In some implementations, the ionic radius of M ranges from 53 pm to 70 pm.

[0061] In this embodiment, the ionic radius of the non-nickel-manganese trivalent metal element M ranges from 53 pm to 70 pm, a range similar to that of Ni. 3+ and Mn 3+ The ionic radius is approximately the same as that of the ions, which can effectively enter the Ni and Mn lattice sites in the crystal structure, reducing lattice distortion, improving the stability of the crystal structure, and enhancing the uniformity of the content of non-nickel manganese trivalent metal elements M at doped Ni and Mn sites. Simultaneously, it can also make Mn... 3+ Reducing and maintaining manganese leaching within a certain range is beneficial for minimizing manganese leaching. This improves battery cycle life through a dual mechanism: enhancing the structural stability of lithium nickel manganese oxides containing non-nickel trivalent manganese metal elements and reducing Mn leaching. The ionic radius range of non-nickel trivalent manganese metal elements can be 53 pm, 56 pm, 60 pm, 65 pm, 66 pm, 70 pm, or any combination of two of these values, such as 53 pm~60 pm, 60 pm~66 pm, 66 pm~70 pm, etc.

[0062] In some implementations, M includes one or more of Sc, Cr, Fe, Co, Ga, and Rh.

[0063] In the embodiments of this application, the aforementioned non-nickel-manganese trivalent metal element M and Ni 3+ and Mn 3+The ionic radii are more similar, making it easier for them to enter the Ni and Mn sites in the crystal structure, reducing lattice distortion, improving the stability of the crystal structure, and enhancing the uniformity of the content of non-nickel manganese trivalent metal elements at Ni and Mn sites. At the same time, by controlling the ratio of the above-mentioned non-nickel manganese trivalent metal elements to Ni and Mn elements, the content of Mn can be reduced. 3+ Maintaining these values ​​within a certain range helps reduce manganese leaching. This improves battery cycle life through a dual mechanism of enhancing the structural stability of lithium nickel manganese oxides containing non-nickel manganese trivalent metal elements and reducing Mn leaching.

[0064] In some embodiments, when the positive electrode is in a fully discharged state, the active Mn in the positive electrode... 3+ The molar ratio with active lithium is 0~8%.

[0065] In this embodiment of the application, under the fully discharged state, the active Mn in the positive electrode is controlled... 3+ A molar ratio of 0% to 8% with active lithium results in higher stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements. This reduces the amount of Mn dissolved, decreasing the amount of elemental Mn deposited on the negative electrode, thus mitigating damage to the solid electrolyte interphase (SEI) film and improving the cycle stability of the lithium-ion secondary battery. Under full discharge conditions, the molar ratio of active Mn³⁺ to active lithium in the positive electrode can be controlled to be 0%, 1%, 2%, 3%, 3.3%, 4%, 4.6%, 5%, 6%, 6.3%, 7%, 7.4%, 8%, or any range of any two of these values, such as 0–3%, 3%–6.3%, 6.3%–8%.

[0066] In this application embodiment, the positive electrode in the fully discharged state refers to the state in which the positive electrode has a lithium battery potential of 3.0V to 3.5V.

[0067] In this embodiment of the application, when the positive electrode is in a fully discharged state, the active Mn in the positive electrode is... 3+The molar ratio of the positive electrode to active lithium (denoted by "IC") can be obtained by testing using the following method: A half-cell is formed by assembling the positive electrode and the lithium sheet. The cell is then discharged at a constant current of 0.1C to 3V, allowed to stand for 5 minutes, and then discharged at a constant current of 0.04C to 3V. Next, it is charged at a constant current of 0.1C to 4.95V, and then charged at a constant voltage of 4.95V to 0.05C. The relevant capacity values ​​are extracted from the charging capacity to calculate the total capacity, i.e., the charging capacity Q1 in the 3.5V~4.4V range and the total charging capacity Qtotal in the 3.5V~4.95V range, i.e., IC = Q1 / Qtotal. The 0.1C constant current discharge reduces polarization; the 0.04C constant current discharge step ensures sufficient Li is retained or embedded in the negative electrode active material. In a specific embodiment of this application, the positive electrode and the lithium sheet can form a coin cell.

[0068] In some embodiments, when the positive electrode is in a fully discharged state, the active Mn in the positive electrode... 3+ The molar ratio with active lithium is 0~5%.

[0069] In some implementations, under full discharge conditions, the active Mn in the positive electrode is controlled... 3+ A molar ratio of 0% to 5% with active lithium results in higher stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements. This reduces the amount of Mn leaching, decreases the amount of elemental Mn deposited on the negative electrode, and lessens damage to the solid electrolyte interphase (SEI) film, thereby improving the cycle stability of the lithium-ion secondary battery. Specifically, in the fully discharged state, the molar ratio of active Mn3+ to active lithium in the positive electrode can be 0, 0.3%, 0.6%, 1%, 1.3%, 1.8%, 2%, 3%, 3.3%, 4%, 5%, or any range of two of these values, such as 0–1.8%, 1.8%–3.3%, or 3.3%–5%.

[0070] In some implementations, -0.03≤(x+g)-(y+t)≤0.03, 0<x+g≤0.25.

[0071] In the embodiments of this application, the co-doping of M, G, and T elements conforms to the principle that the subscripts x+g and y+t in the chemical formula are equal or nearly equal, which can effectively control Mn. 3+ Maintaining chemical valence balance by controlling the content of M and G elements improves the structural stability of the positive electrode active material and reduces Mn dissolution, thereby enhancing the cycle stability and cycle life of lithium-ion secondary batteries. By controlling the range of x+g and the doping amounts of M and G elements, valence balance is achieved without increasing the Mn3+ content, which is beneficial for controlling Mn content. 3+The content of [unspecified element] is within a favorable range. By controlling the range of g within the above range, low-valent manganese (Mn) can be suppressed by doping with low-valent elements (+1 valent metal elements and / or +2 valent metal elements). 2+ The formation of [a specific element] can reduce manganese leaching while maintaining energy density, resulting in a better energy density for lithium-ion secondary batteries. By controlling the range of t within the aforementioned range, the doping amount of high-valence elements (+4, +5, +6 valence elements) can be controlled to stabilize oxygen in lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, thereby improving the stability of the crystal structure of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements. Here, x+g can be 0.01, 0.05, 0.08, 0.1, 0.12, 0.15, 0.16, 0.2, 0.22, 0.25, etc., or any range of two of the above values, such as 0.01~0.05, 0.05~0.12, 0.12~0.25, etc.

[0072] In some embodiments, G comprises a +2 valent metal element with an ionic radius of 49 pm to 89 pm. In embodiments of this application, the ionic radius of element G is in the range of 49 pm to 89 pm, such that element G reacts with Ni... 2+ The approximate ionic radius of G allows it to better enter the crystal structure and mix with Ni, which can improve the structural stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, thereby improving the structural stability of lithium-ion secondary batteries.

[0073] In some embodiments, T includes +4, +5, and +6 valent metals with ionic radii of 33 pm to 73 pm. In the embodiments of this application, the ionic radius of element T is between 33 pm and 73 pm, such that element T reacts with Mn. 4+ Its ionic radius is similar to that of Mn, so it can easily enter the crystal structure and form mixed arrangement with Mn, which can improve the stability of the crystal structure.

[0074] In some embodiments, 0 < y + t ≤ 0.2. In the embodiments of this application, by controlling the range of y + t within the above range, the Mn element content in the crystal structure is made higher, which can stabilize the spinel structural framework.

[0075] In some embodiments, G includes one or more of Mg, Cu, and Zn. In the embodiments of this application, Mg, Cu, and Zn are more likely to enter the crystal structure and mix with Ni to improve the structural stability of the positive electrode active material.

[0076] In some embodiments, T includes one or more of Si, P, Ti, V, Ge, As, Se, Zr, Nb, Mo, Sn, Sb, Te, Ta, and W. In embodiments of this application, Si... 4+ P 5+ Ti4+ V 5+ 、Ge 4+ As 5+ Se 6+ Zr 4+ 、Nb 5+ Mo 6+ Sn 4+ Ta 5 + Sb 5+ W 6+ Te 4+ These elements can enter the crystal structure and form strong bonds with oxygen, improving the stability of lithium nickel manganese oxides containing non-nickel manganese trivalent metal elements; additionally, Nb 5+ Mo 6+ Sn 4+ Ta 5+ Sb 5+ W 6+ Te 4+ The larger plasma radius can increase the lattice spacing and reduce Li + Migration energy barrier, improving rate performance.

[0077] In some embodiments, 0 < y + t ≤ 0.1. In the embodiments of this application, y + t is within the above range, which results in a higher Mn content in the crystal structure of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, thus increasing the stability of the spinel structural framework and the overall stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements.

[0078] In some embodiments, 0.01 ≤ x ≤ 0.1. In the embodiments of this application, x is within the above range. By doping with an appropriate amount of non-nickel manganese trivalent metal M, the stability of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements can be improved, while the activity of lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements can be taken into account, so that it has a higher energy density.

[0079] In some embodiments, the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Mn. 3+ Mn 3+ The proportion IM of Mn to the total Mn satisfies 0 ≤ IM ≤ 5%. In the embodiments of this application, Mn is controlled... 3+ When the proportion of Mn to total Mn falls within the above range, the amount of Mn dissolved is relatively small, which can reduce the amount of Mn deposited on the negative electrode, reduce the damage of Mn dissolution to the SEI film, improve the cycle stability of the lithium-ion secondary battery, and increase the cycle life. Here, IM can be 0, 0.1%, 0.6%, 1%, 2%, 4%, 5%, etc., or any range of two of the above values, such as 0~0.6%, 0.6%~2%, 2%~5%, etc.

[0080] In some implementations, 0 ≤ IM ≤ 3%. In this application's implementation, Mn is controlled... 3+ The proportion of Mn to the total Mn is within the above range. 3+ The content of Mn is relatively low. Furthermore, by doping with non-nickel-manganese trivalent metal elements, the structural stability of the positive electrode active material can be improved. Simultaneously, the amount of Mn leached is low, which reduces the amount of Mn deposited on the negative electrode, minimizing the damage to the SEI film caused by Mn leaching, and improving the cycle stability and cycle life of the lithium-ion secondary battery. Here, IM can be 0, 0.1%, 0.6%, 1%, 3%, etc., or a range of any two of the above values, such as 0~0.6%, 0.6%~1%, 1%~3%, etc.

[0081] In the embodiments of this application, Mn 3+ The proportion of Mn (IM) to the total Mn can be determined by titration.

[0082] In some embodiments, the lithium-ion secondary battery includes a manganese scavenger coated and / or attached to the surface of particles containing lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements; and / or the manganese scavenger is located on the surface of the positive electrode active material layer; and / or on the surface of the separator; and / or the manganese scavenger is located on the surface of the negative electrode active material layer of the negative electrode sheet.

[0083] In this embodiment, the manganese scavenger can interact with manganese ions through chemical absorption or physical adsorption, effectively capturing manganese ions dissolved from lithium nickel manganese oxide particles containing non-nickel manganese trivalent metal elements due to structural instability. This reduces manganese ion deposition on the negative electrode surface, minimizes damage to the solid electrolyte interphase (SEI) film on the negative electrode surface, and lowers lithium consumption during battery cycling. The manganese scavenger can also coat the surface of lithium nickel manganese oxide particles containing non-nickel manganese trivalent metal elements to form a protective layer, directly adsorbing manganese ions dissolved from these particles. This shortens the path for capturing manganese ions and improves the capture efficiency. Alternatively, the manganese scavenger can be dispersed in the positive electrode active material layer and adhered to the surface of lithium nickel manganese oxide particles containing non-nickel manganese trivalent metal elements, also adsorbing manganese ions dissolved from these particles and reducing the amount of manganese ions reaching the negative electrode surface. Manganese scavengers can be placed on the surface of the positive electrode active material layer, the separator surface, or the negative electrode active material layer. All of these can reduce the amount of manganese ions reaching the surface of the negative electrode active material layer, reduce the damage of manganese ions to the solid electrolyte interphase (SEI) film, and improve the cycle stability of lithium-ion secondary batteries.

[0084] In some embodiments, the manganese scavenging agent includes one or more of the following: substances containing polyoxoanionic groups, lithium-rich substances, and adsorbent substances, wherein the specific surface area of ​​the adsorbent substance is greater than or equal to 100. 2 / g, and less than or equal to 3000m 2 / g. In the embodiments of this application, substances containing polyoxoanion groups have a strong attraction to positive charges, and can exert a strong electrostatic attraction on manganese ions, anchoring or capturing manganese ions on the manganese scavenger, reducing the amount of manganese reaching the negative electrode. Lithium-rich substances readily undergo Li-Mn exchange with manganese ions, capturing Mn and releasing Li, which is beneficial for reducing the amount of manganese reaching the negative electrode. Adsorbent substances can physically adsorb manganese ions, reducing the amount of manganese reaching the negative electrode. Therefore, substances containing polyoxoanion groups, lithium-rich substances, and adsorbent substances can all reduce the damage of manganese ions to the solid electrolyte interphase (SEI) film, improving the cycle stability of lithium-ion secondary batteries.

[0085] In this application, lithium-rich substances refer to lithium elements accounting for a mass percentage of 5% or greater than or equal to 5% of the lithium-rich substances; or lithium-rich substances include LiM'. a O b Among them, substances with a Li:M' molar ratio greater than or equal to 1:1 are lithium-rich substances.

[0086] In some embodiments, the polyoxygen anion group material includes one or more of lithium phosphate, lithium hydrogen phosphate, lithium dihydrogen phosphate, lithium silicate, lithium sulfate, lithium polyacrylate, and lithium carbonate. In the embodiments of this application, lithium phosphate, lithium hydrogen phosphate, lithium dihydrogen phosphate, lithium silicate, lithium sulfate, lithium polyacrylate, and lithium carbonate all have a strong attraction to positive charges, and can have a strong electrostatic attraction to manganese ions, anchoring or capturing manganese ions on the manganese scavenger, reducing the amount of manganese reaching the negative electrode, and improving the cycle stability of the lithium-ion secondary battery.

[0087] In some embodiments, the lithium-rich material includes one or more of LiNiO2, Li5FeO4, Li2MnO3, Li6CoO4, Li2CuO2, Li2MoO2, Li5ReO6, Li2O, Li2O2, and Li2S. In the embodiments of this application, the above-mentioned lithium-rich material can undergo Li-Mn exchange with manganese ions to capture Mn and release Li, which helps reduce the amount of manganese reaching the negative electrode. The adsorbent material can physically adsorb manganese ions, reducing the amount of manganese reaching the negative electrode and improving the cycle stability of the lithium-ion secondary battery.

[0088] In some embodiments, the adsorbent material includes one or more of activated carbon, carbon nanotubes, and zeolite. In the embodiments of this application, the above-mentioned adsorbent material can physically adsorb manganese ions, reduce the amount of manganese reaching the negative electrode, and improve the cycle stability of the lithium-ion secondary battery.

[0089] In this embodiment, the mass ratio of the chemically absorbed substance to the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements is (0~30):100. By controlling the chemically absorbed substance and the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements within the above range, it is beneficial to reduce the amount of manganese reaching the surface of the negative electrode, improve the cycle stability of the lithium-ion secondary battery, and at the same time enable the lithium-ion secondary battery to have a higher energy density.

[0090] The second aspect of this application also includes a positive electrode active material, which is the same as the positive electrode active material in the lithium-ion secondary battery of the first aspect. Specifically, the positive electrode active material includes a lithium nickel manganese oxide containing a non-nickel manganese trivalent metal element, and the crystal structure of the lithium nickel manganese oxide containing the non-nickel manganese trivalent metal element includes a spinel structure; the lithium nickel manganese oxide containing the non-nickel manganese trivalent metal element includes Li b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k-q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is a non-nickel-manganese trivalent metal element with an ionic radius ranging from 33 pm to 90 pm; G includes a +1 valent metal element and / or a +2 valent metal element; T includes one or more of +4, +5, and +6 valent elements; Q includes one or more of F, Cl, Br, I, S, and N; 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5; where x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, and -0.03 ≤ xy ≤ 0.03.

[0091] In this embodiment, the spinel-type lithium nickel manganese oxide is less prone to phase transition and exhibits relatively high stability. Lithium nickel manganese oxides containing non-nickel-manganese trivalent metal elements include Li... b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k-q Q qBy employing a non-nickel-manganese trivalent metal element M with an ionic radius of 33 pm to 90 pm to dope spinel-structured lithium nickel-manganese oxide, the structural stability can be improved by using M as a dopant. This is because the ionic radius of M is comparable to that of nickel and manganese ions, and it can maintain valence equilibrium (i.e., when a non-nickel-manganese trivalent metal element is doped into spinel-structured lithium nickel-manganese oxide, the valence of nickel and manganese in the spinel structure remains unchanged or almost unchanged). Furthermore, it can be mixed with Ni and Mn elements, thus enhancing structural stability. Simultaneously, by controlling the doping amount of M, and ensuring that 0 < x ≤ 0.2, 0 < y ≤ 0.2, and the difference between x and y does not exceed 0.03, without increasing Mn... 3+ Maintaining chemical valence balance while taking into account Mn content 3+ Low content reduces the amount of Mn leaching from the positive electrode active material; A element doping can enter the Li sites in the crystal structure; G is a +1 and / or +2 valence metal element, and after doping into Ni and Mn sites, its low valence state increases the valence state of Mn, thus reducing Mn content. 3+ By doping with T elements of +4, +5, and +6 valence, the high valence of T elements forms strong bonds with O, stabilizing the structure. Q is a strongly electronegative element, which is doped into the O site and forms strong bonds with Ni, Mn, and M, stabilizing the structure. The synergistic effect of elements such as A, M, G, T, and Q forms a specific chemical formula structure.

[0092] The third aspect of this application also includes a method for preparing a positive electrode active material, comprising:

[0093] S110: Lithium salt, nickel source, manganese source and dopant source are mixed and calcined at a first temperature for a first time to form an intermediate product, wherein the first temperature is 600℃~1200℃, the first time is 1h~50h, the dopant source includes non-nickel manganese trivalent metal source, or the dopant source includes non-nickel manganese trivalent metal source, and also includes one or more of A source, G source, T source and Q source, A source includes one or more of Na source, K source, Rb source and Cs source, G source includes +1 valence metal source and / or +2 valence metal source, T source includes raw material containing +4, +5 and +6 valence elements, and Q source includes one or more of F source, Cl source, Br source, I source, S source and N source.

[0094] In some embodiments of this application, a solid-state sintering method is used to mix lithium salt, nickel source, manganese source, and dopant source, and then sinter the mixture at 600℃ to 1200℃ to obtain an intermediate product. The intermediate product in these embodiments is a lithium nickel manganese oxide doped with non-nickel-manganese trivalent metal elements. The calcination temperature can be 600℃, 700℃, 800℃, 860℃, 900℃, 1000℃, 1050℃, 1100℃, 1200℃, etc., or a range of any two of the above values, such as 600℃~860℃, 860℃~1050℃, 1050℃~1200℃, etc.

[0095] In some embodiments of this application, the initial calcination time can be 1 hour to 50 hours. By controlling the calcination time within the above range, it is beneficial for solid-state sintering to form intermediate products. The calcination time can be 1 hour, 10 hours, 12 hours, 17 hours, 20 hours, 30 hours, 36 hours, 40 hours, 46 hours, 50 hours, etc., or a range of any two of the above values, such as 1 hour to 10 hours, 10 hours to 36 hours, 36 hours to 50 hours, etc.

[0096] In some embodiments of this application, the non-nickel manganese trivalent metal source can be a non-nickel manganese trivalent metal oxide, etc. The lithium salt can be lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, etc., the nickel source can be nickel monoxide, nickel trioxide, nickel nitrate, nickel chloride, nickel acetate, nickel hydroxide, etc., and the manganese source can be manganese tetroxide, manganese dioxide, manganese nitrate, manganese acetate, manganese carbonate, etc.

[0097] In some embodiments of this application, lithium salt, nickel source, manganese source, and non-nickel-manganese trivalent metal source are mixed, and one or more of source A, source G, source T, and source Q may be further added and mixed to obtain intermediate products including Li. b A a Ni 0.5-x- g Mn 1.5-y-t M x+y G g T t O 4-k-q Q q In this system, the A source includes chlorides, sulfides, etc., containing element A; the G source can be an oxide or hydroxide of element G; and the T source can be an oxide or hydroxide of element T. Element G can be an element with a +1 or +2 valence, such as Mg, Cu, Zn, etc. Element T can be elements with +4, +5, or +6 valence ions, such as Si, P, Ti, V, Ge, As, Se, Zr, Nb, Mo, Sn, Sb, Te, Ta, W, etc. Element Q can be F, Cl, Br, I, S, N, etc., and the Q source can be a halide, sulfide, nitride, etc.

[0098] In some embodiments of this application, the molar ratio of non-nickel manganese trivalent metal elements in the non-nickel manganese trivalent metal source to manganese elements in the manganese source is less than or equal to 0.33; and / or, the molar ratio of non-nickel manganese trivalent metal elements in the non-nickel manganese trivalent metal source to nickel elements in the nickel source is less than or equal to 2. In embodiments of this application, by adjusting the ratio of the aforementioned non-nickel manganese trivalent metal elements to Ni and Mn elements, the reduction of Mn is also considered. 3+ And keep it within a certain numerical range (Mn) 3+The content of nickel, manganese, and non-nickel-manganese trivalent metal sources can be represented by the ratio of their charging capacity in the 3.5V~4.4V range to the total charging capacity in the 3.5V~4.95V range (IC). This ratio helps reduce Mn dissolution, decreases the damage to the SEI film caused by Mn deposition on the negative electrode, improves the cycle stability of lithium-ion secondary batteries, and increases cycle life. More specifically, the molar ratio of nickel, manganese, and non-nickel-manganese trivalent metal sources can be determined according to the Li... b A a Ni 0.5-x- g Mn 1.5-y-t M x+y G g T t O 4-k-q Q q The molar ratios are added according to the following conditions: 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 < x ≤ 0.2, 0 < y ≤ 0.2, -0.03 ≤ xy ≤ 0.03, -0.03 ≤ (x + g) - (y + t) ≤ 0.03, 0 < x + g ≤ 0.25, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5. The molar ratio of the non-nickel trivalent manganese metal element in the non-nickel trivalent metal source to the manganese element in the manganese source can be 0.01, 0.1, 0.14, 0.21, 0.3, 0.33, etc., or a range consisting of any two of the above values, such as 0.01~0.1, 0.1~0.21, 0.21~0.33, etc., or less than 0.01 and greater than 0. The molar ratio of non-nickel manganese trivalent metal elements in the non-nickel manganese trivalent metal source to nickel elements in the nickel source can be less than 0.01, 0.5, 0.6, 0.8, 1, 1.4, 1.6, 2, etc., or a range of any two of the above values, such as 0.01~0.5, 0.5~0.8, 0.8~1.6, 1.6~2, etc., or less than 0.01 and greater than 0.

[0099] S120: The intermediate product is kept at a second temperature for a second time to form a positive electrode active material. The second temperature is 500℃~850℃, and the second time is 1h~50h. The positive electrode active material includes lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements. The crystal structure of the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes a spinel structure. The lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Li... b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k-q Q qWherein, A includes one or more of Na, K, Rb, and Cs; M is a non-nickel-manganese trivalent metal element with an ionic radius ranging from 33 pm to 90 pm; G includes a +1 valent metal element and / or a +2 valent metal element; T includes one or more of +4, +5, and +6 valent elements; Q includes one or more of F, Cl, Br, I, S, and N; 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, and 0 ≤ q ≤ 0.5; where x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, and -0.03 ≤ xy ≤ 0.03.

[0100] In this embodiment, further calcination at a second temperature is used to control Ni segregation. Ni segregation inevitably leads to an increase in the oxidation state of Ni ions, thereby reducing the oxidation state of Mn ions. The temperature range of 500℃ to 850℃ can effectively reduce Ni segregation, thus avoiding the formation of a large number of low-valence Mn ions and controlling the Mn content in the intermediate product. 3+ The content of elements is adjusted to obtain the final product, such that the transition metal ions in the crystal structure of the final product are arranged in a disordered manner.

[0101] In some embodiments of this application, the first temperature and the second temperature are different, and the Mn content in the intermediate product is controlled by controlling the different temperatures in stages. 3+ The abundance of elements and their disordered structure.

[0102] In some embodiments of this application, the second temperature is lower than the first temperature. By controlling the second temperature to be lower than the first temperature, it is beneficial to regulate the Mn content in the intermediate product. 3+ The abundance of elements and their disordered structure.

[0103] The preparation method of this application, after obtaining a lithium nickel manganese oxide intermediate product doped with non-nickel manganese trivalent metal elements, further calcines it at a second temperature for a certain time to control the nickel-manganese mixture and thus control the Mn content in the intermediate product. 3+ The content of elements determines the final product.

[0104] This application provides a fourth aspect of an electrical device, comprising a lithium-ion secondary battery as described in the first aspect, and / or a positive electrode active material as described in the second aspect, and / or a positive electrode active material prepared by the preparation method of the third aspect. The electrical device according to the embodiments of this application has the same advantages as the lithium-ion secondary battery of the first aspect, and / or the same advantages as the positive electrode active material of the second aspect, and / or the same advantages as the positive electrode active material prepared by the preparation method of the third aspect.

[0105] The lithium-ion secondary battery disclosed in this application can be used in electrical devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0106] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0107] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A lithium-ion secondary battery 100 is installed inside the vehicle 1000, and the lithium-ion secondary battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The lithium-ion secondary battery 100 can be used to power the vehicle 1000; for example, the lithium-ion secondary battery 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the lithium-ion secondary battery 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.

[0108] In some embodiments of this application, the lithium-ion secondary battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0109] Please refer to Figure 2 , Figure 2This is an exploded structural diagram of a lithium-ion secondary battery 100 provided in some embodiments of this application. The lithium-ion secondary battery 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, jointly defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 jointly define the space. Alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0110] In the lithium-ion secondary battery 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the casing 10. Alternatively, the lithium-ion secondary battery 100 can also consist of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module, and then these battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the casing 10. The lithium-ion secondary battery 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0111] Each battery cell 20 can be a battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0112] Please refer to Figure 3 , Figure 3 This is an exploded structural diagram of a battery cell 20 provided in some embodiments of this application. The battery cell 20 refers to the smallest unit that makes up a battery. Figure 3 The battery cell 20 includes an end cap 21, a housing 22, a cell assembly 23, and other functional components.

[0113] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, allowing battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 21a can be provided on end cap 21. Electrode terminals 21a can be used for electrical connection with cell assembly 23 to output or input electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0114] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the cell assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the cell assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0115] The cell assembly 23 is the component in the battery cell 20 where the electrochemical reaction occurs. The casing 22 may contain one or more cell assemblies 23. The cell assembly 23 is mainly formed by winding or stacking positive and negative electrode plates, and typically a separator is provided between the positive and negative electrode plates. The portions of the positive and negative electrode plates containing active material constitute the main body of the cell assembly, while the portions of the positive and negative electrode plates without active material each constitute a tab 23a. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs 23a connect the electrode terminals to form a current loop.

[0116] Typically, a lithium-ion secondary battery 100 includes a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits between the electrodes while allowing ions to pass through.

[0117] [Positive electrode plate]

[0118] In some embodiments, the positive electrode includes a positive current collector and a layer of positive active material disposed on at least one surface of the positive current collector.

[0119] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0120] In some embodiments, the positive 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 substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0121] In some embodiments, the positive electrode active material layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0122] In some embodiments, the positive electrode active material layer may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0123] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0124] [Negative electrode plate]

[0125] The negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector, wherein the negative active material layer includes a negative active material.

[0126] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0127] 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 may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0128] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0129] In some embodiments, the negative electrode active material layer may optionally include a binder. The binder may 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).

[0130] In some embodiments, the negative electrode active material layer may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0131] In some embodiments, the negative electrode active material layer may also optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0132] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0133] [Isolation membrane]

[0134] In some embodiments, the battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0135] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0136] In some embodiments, the separator includes a base membrane and a functional coating disposed on one or both sides of the base membrane. The base membrane includes one or more of polyethylene, polypropylene, polyimide, cellulose membrane, and inorganic material membranes; the functional coating includes inorganic ceramic materials and organic polymer materials, wherein the inorganic ceramic materials include oxides such as alumina, silicon dioxide, zirconium oxide, magnesium oxide, and titanium dioxide, and may also include nitrides such as aluminum nitride and boron nitride. The organic polymer materials include polyimide, cellulose micro / nanofibers, etc.

[0137] In some embodiments, the separator also includes a manganese trapping agent, which may be disposed in the functional coating and may be disposed in the functional coating away from the base film once.

[0138] [Electrolytes]

[0139] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0140] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0141] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0142] In some embodiments, the solvent may 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, butyl 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, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0143] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into a battery cell assembly using a winding or stacking process.

[0144] In some embodiments, the housing 22 may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.

[0145] This application does not impose any particular restrictions on the shape of the battery cell 20, which can be cylindrical, square or other arbitrary shapes.

[0146] The beneficial effects of this application are further illustrated below with reference to the embodiments.

[0147] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. 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 of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0148] I. Battery Component Fabrication

[0149] Example 1

[0150] Preparation of the positive electrode sheet

[0151] Step 1) Mix lithium salt, nickel source, manganese source, and non-nickel manganese trivalent metal source, wherein the molar ratio of Li, Ni, Mn, and non-nickel manganese trivalent metal M is 1:0.45:1.45:0.1; calcine at a first temperature for a first time to form an intermediate product. The lithium salt is lithium carbonate, the nickel source is nickel monoxide, the manganese source is manganese tetroxide, and the non-nickel manganese trivalent metal source is Fe2O3. The first temperature is 950℃, and the first time is 10 hours.

[0152] Step 2) The intermediate product is kept at a second temperature for a second time, the second temperature is 600℃ and the second time is 10h, to obtain the positive electrode active material.

[0153] Step 3) The positive electrode active material, binder polyvinylidene fluoride (PVDF), and conductive agent (carbon black) are mixed evenly at a weight ratio of 97:1:2 and dispersed in the solvent N-methylpyrrolidone (NMP). After thorough mixing, a positive electrode slurry is prepared. The positive electrode slurry is then uniformly coated onto two opposite surfaces of the positive electrode current collector aluminum foil. After drying, cold pressing, and slitting, the positive electrode sheet is obtained. The loading of positive electrode active material on one side of the positive electrode sheet is 0.02 g / cm³. 2 .

[0154] Preparation of the negative electrode sheet

[0155] Artificial graphite (negative electrode active material), acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC-Na) (thickener) were dissolved in deionized water at a mass ratio of 96:1:1:2 and thoroughly mixed to prepare a negative electrode slurry. The negative electrode slurry was then coated onto a copper foil (negative electrode current collector), followed by drying, cold pressing, and slitting to obtain the negative electrode sheet. The loading of negative electrode active material on one side of the negative electrode sheet was 0.008 g / cm³. 2 .

[0156] Preparation of Electrolyte

[0157] Methyltrifluoroethyl carbonate (FEMC) and fluoroethylene carbonate (FEC) were mixed at a volume ratio of 8:2. LiPF6 was then dissolved in the above solution to obtain an electrolyte in which the molar concentration of LiPF6 was 1 mol / L.

[0158] [Septum]

[0159] Polypropylene film is used as the separator.

[0160] [Battery Manufacturing]

[0161] The positive electrode, separator, and negative electrode prepared above are arranged in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The mixture is then shaped and packaged in an aluminum-plastic bag. Electrolyte is injected, and after encapsulation, formation capacity is measured to obtain a lithium-ion secondary battery (soft-pack battery).

[0162] Comparative Example 1

[0163] The difference from Example 1 is that step 1) in the preparation of the positive electrode does not include a non-nickel-manganese trivalent metal source, and the molar ratio of Li, Ni, and Mn is 1:0.5:1.5. Everything else is the same as in Example 1. The specific step 1) in the preparation of the positive electrode is as follows:

[0164] Step 1) Mix lithium salt, nickel source, and manganese source, wherein the molar ratio of Li, Ni, and Mn is 1:0.5:1.5; calcine at a first temperature for a first time to form an intermediate product. The lithium salt is lithium carbonate, the nickel source is nickel monoxide, and the manganese source is manganese tetroxide. The first temperature is 950℃, and the first time is 10 hours.

[0165] Comparative Examples 2 to 4

[0166] The differences from Example 1 are detailed in Table 1; otherwise, they are the same as in Example 1 and will not be repeated here. Specifically, the non-nickel manganese trivalent metal source used in Comparative Example 3 is boron oxide, and the non-nickel manganese trivalent metal source used in Comparative Example 4 is lanthanum trioxide.

[0167] Example 2 to Example 8

[0168] The difference from Example 1 lies in the use of a non-nickel-manganese trivalent metal source in step 1) of the preparation of the positive electrode. Specifically, Example 2 used aluminum oxide, Example 3 used scandium oxide, Example 4 used chromium oxide, Example 5 used cobalt oxide, Example 6 used gallium oxide, Example 7 used indium oxide, and Example 8 used yttrium oxide. The other steps are the same as in Example 1 and will not be repeated here.

[0169] Examples 9 to 13

[0170] The main difference between Examples 9 to 13 and Example 1 lies in the control of the first temperature, the first time, the second temperature, and the second time, as detailed in Table 3. The other aspects are the same as in Example 1 and will not be repeated here.

[0171] Examples 14 to 20

[0172] The main difference between Examples 14 to 20 and Example 1 is the change in the molar ratio of Ni, Mn, and non-nickel manganese trivalent metal M, as detailed in Table 4. The other aspects are the same as in Example 1 and will not be repeated here.

[0173] Example 21

[0174] The difference from Example 1 lies in step 1) of the preparation of the positive electrode sheet; otherwise, it is the same as in Example 1. Specifically, step 1) of the preparation of the positive electrode sheet is as follows:

[0175] Step 1) Mix lithium salt, nickel source, manganese source, non-nickel manganese trivalent metal source, G source, and T source, wherein the molar ratio of Li, Ni, Mn, non-nickel manganese trivalent metal, G, and T is 1:0.45:1.45:0.1; calcine at a first temperature for a first time to form an intermediate product. The lithium salt is lithium carbonate, the nickel source is nickel monoxide, the manganese source is manganese tetroxide, the non-nickel manganese trivalent metal source is Fe₂O₃, the G source is copper oxide, and the T source is titanium dioxide; the first temperature is 950℃, and the first time is 10 hours.

[0176] Example 22

[0177] The difference from Example 1 lies in step 3) of the preparation of the positive electrode sheet; otherwise, it is the same as in Example 1. The specific step 3) of the preparation of the positive electrode sheet is as follows:

[0178] The positive electrode active material and manganese scavenger Li3PO4 were mixed at a mass ratio of 1:20 to form a first mixed material. This first mixed material, along with the binder polyvinylidene fluoride (PVDF) and the conductive agent (carbon black), were mixed uniformly at a weight ratio of 97:1:2 and dispersed in the solvent N-methylpyrrolidone (NMP). After thorough mixing, a positive electrode slurry was prepared. The positive electrode slurry was uniformly coated onto two opposite surfaces of the positive electrode current collector aluminum foil. Following drying, cold pressing, and slitting, the positive electrode sheet was obtained. The loading of the positive electrode active material on one side of the positive electrode sheet was 0.02 g / cm³. 2 .

[0179] Example 23

[0180] The difference from Example 1 lies in step 3) of the preparation of the positive electrode sheet; otherwise, it is the same as in Example 1. The specific step 3) of the preparation of the positive electrode sheet is as follows:

[0181] Step 3) Mix the positive electrode active material, binder polyvinylidene fluoride (PVDF), and conductive agent (carbon black) in a weight ratio of 97:1:2, disperse them in the solvent N-methylpyrrolidone (NMP), and stir thoroughly to prepare a positive electrode slurry; coat the positive electrode slurry evenly on the two opposite surfaces of the positive electrode current collector aluminum foil to form a positive electrode active material layer;

[0182] With a specific surface area of ​​1000m 2 / g of activated carbon and the binder polyvinylidene fluoride (PVDF) are mixed at a mass ratio of 9:1 and dispersed in the solvent N-methylpyrrolidone (NMP). After thorough mixing, a slurry is prepared. The slurry is then uniformly coated onto the surface of the positive electrode active material layer to form a manganese-capturing layer with a thickness of [missing information]. The mass ratio of activated carbon to positive electrode active material in the manganese-capturing layer is 1:20.

[0183] II. Characterization Test

[0184] The specific testing methods for the relevant parameters in the above embodiments are as follows:

[0185] 1) When the positive electrode is in a fully discharged state, the active Mn in the positive electrode... 3+ Molar ratio (IC) test with active lithium

[0186] 1.1) Fabrication of Button Semi-Cell Electrode (1) The positive electrode active material, conductive carbon black, and PVDF are mixed in a weight ratio of 90:5:5. An appropriate amount of N-methylpyrrolidone is added and stirred evenly to obtain a positive electrode slurry. The obtained positive electrode slurry is coated onto aluminum foil and dried to obtain a positive electrode sheet. The loading of lithium nickel manganese composite oxide on the positive electrode sheet is 0.015 g / cm³. 2 (2) Mix methyltrifluoroethyl carbonate (FEMC) and fluoroethylene carbonate (FEC) at a volume ratio of 8:2, and then dissolve LiPF6 in the above solution to obtain an electrolyte with a molar concentration of 1 mol / L for LiPF6. (3) Use a 12 μm thick polypropylene film (16 mm in diameter) as a separator, and place the lithium sheet, separator, and positive electrode in sequence, so that the separator is positioned between the lithium metal sheet and the positive electrode to act as a separator. Inject the electrolyte and assemble a CR2030 (20 mm in diameter, 3 mm in thickness) coin cell. Let it stand for 24 h to obtain a half cell.

[0187] 1.2) IC Testing

[0188] At 25°C, the coin cells prepared with the positive electrode active materials of each embodiment and comparative example were discharged at a constant current of 0.1C to ≤3V, and after standing for 5 minutes, discharged at a constant current of 0.04C to ≤3V. After standing for 5 minutes, they were charged at a constant current of 0.1C to a voltage of 4.95V, and then charged at a constant voltage of 4.95V to 0.05C. The charging capacity of 3.5V~4.4V (C1) and the charging capacity of 3.5~4.95V (C2) were extracted from the original charging data. C1 / C2 is the capacity ratio of 3.5V~4.4V, IC.

[0189] 2) Cyclic performance test

[0190] At 45°C, a lithium-ion secondary battery (pouch cell) is charged at a constant current of 0.5C to a voltage of 4.85V, then charged at a constant voltage of 4.85V to a current of 0.05C. After resting for 5 minutes, the pouch cell is discharged at a constant current of 0.5C to a voltage of 3.5V, and then rested for 5 minutes. This process is repeated. The ratio of the discharge capacity C200 of the 200th cycle to the discharge capacity C1 of the first cycle, C200 / C1, is the reversible capacity retention rate of the secondary battery after 200 cycles.

[0191] 3) Test of manganese deposition on negative electrode sheet

[0192] The lithium-ion secondary battery that had undergone 200 cycles was disassembled to obtain the negative electrode sheet. The negative electrode sheet was repeatedly immersed in dimethyl carbonate solvent three times, for 30 minutes each time, and fresh solvent was used each time. Then, the manganese content (μg / g) in the negative electrode sheet after deducting the copper foil current collector was detected by inductively coupled plasma optical emission spectrometry. That is, the manganese content is the mass of manganese / (mass of negative electrode film + mass of manganese).

[0193] 4) Characterization methods for the chemical formulas of lithium nickel manganese oxides containing non-nickel manganese trivalent metal elements.

[0194] The evaluation was performed using inductively coupled plasma atomic emission spectrometry (ICP). The specific procedure was as follows: the powder to be tested was placed in a microwave digester (e.g., CEM-Mars6) for digestion, and the digested solution was then passed into an ICP analyzer for testing.

[0195] Table 1. Process and performance parameters of Example 1 and Comparative Examples 1-4.

[0196]

[0197] Table 2 shows the process and performance parameters for Examples 2-8.

[0198]

[0199] Table 3 shows the process and performance parameters for Examples 9-13.

[0200]

[0201] Table 4 shows the process and performance parameters for Examples 14-22.

[0202]

[0203] Table 5 shows the process and performance parameters for Examples 23-25.

[0204]

[0205] Note: In the table above, M represents non-nickel-manganese trivalent metal elements; IC represents the active Mn in the positive electrode when the positive electrode is in a fully discharged state. 3+ The molar ratio to active lithium; x and y correspond to the chemical formulas Li b A a Ni 0.5-x-g Mn 1.5-y-t M x+ y G g T t O 4-k-q Q q The subscripts x and y.

[0206] In summary, as shown in Table 1, based on Comparative Examples 1 to 4, the cycle capacity retention rate of the lithium-ion secondary battery in Example 1 of this application was improved after 200 cycles, and the manganese deposition amount on the negative electrode was reduced. This indicates that Example 1 of this application, by controlling the doping of non-nickel manganese trivalent metal element M, with the ionic radius of M ranging from 33 pm to 90 pm, and the M ionic radius being comparable to that of nickel and manganese ions while maintaining valence balance, and by controlling the difference between the doping amount x and y of the non-nickel manganese trivalent metal element M to not exceed 0.03, resulted in a lower active Mn content in the positive electrode under fully discharged conditions. 3+ The molar ratio (IC) of Mn to active lithium is relatively low. 3+ The lower content reduces the amount of Mn leaching, reduces the damage to the SEI film caused by Mn deposition on the negative electrode, improves the cycle stability of lithium-ion secondary batteries, and increases cycle life.

[0207] As can be seen from Tables 1 and 2, based on Comparative Examples 3 and 4, the ionic radius of the non-nickel manganese trivalent metal element in Comparative Example 3 is less than 33 pm, while the ionic radius of the non-nickel manganese trivalent metal element in Comparative Example 4 is greater than 90 pm. The manganese deposition amount of the negative electrode sheets in Comparative Examples 3 and 4 is relatively high, resulting in low cycle capacity retention. Examples 1-8 of this application, by controlling the doping of non-nickel manganese trivalent metal elements and controlling the difference between the doping amount x and y of the non-nickel manganese trivalent metal element M to not exceed 0.03, can improve the structural stability of the positive electrode active material, reduce the manganese deposition amount of the negative electrode sheet, improve the cycle capacity retention rate, and improve cycle performance.

[0208] As can be seen from Tables 1 and 3, based on Example 9, Example 1, by controlling the second temperature to decrease, resulted in fewer O-site defects in the product, enhanced the structural stability of the positive electrode active material, and increased the active Mn content in the positive electrode sheet under fully discharged conditions. 3+ The molar ratio of Mn to active lithium decreases, resulting in a lower IC value. 3+ With the reduction in content, the amount of Mn dissolved from the positive electrode active material decreases, and the cycle capacity retention rate is improved.

[0209] In Examples 1 and 9-11, the second temperature and second time were varied, with the second temperature controlled between 500℃ and 850℃ and the second time between 1h and 50h. By doping with non-nickel-manganese trivalent metal elements with ionic radii ranging from 33pm to 90pm, the IC value was effectively controlled within the range of 0-8%, resulting in higher structural stability of the positive electrode active material, lower manganese deposition on the negative electrode, less Mn dissolution, and higher cycle capacity retention. In Example 13, when the second temperature exceeded 750℃, the manganese deposition on the negative electrode increased, and the cycle capacity retention decreased, but it was still higher than that of Comparative Examples 1-4. Based on Examples 1 and 12, by varying the first temperature, the manganese deposition on the negative electrode remained relatively low, and the cycle capacity retention was high.

[0210] As can be seen from Tables 1 and 4, based on Examples 1, 14 to 15, -0.03≤xy≤0.03 indicates that the negative electrode of the lithium-ion secondary battery has less manganese deposition and a higher cycle capacity retention rate.

[0211] Based on Examples 1 and 16-20, it can be seen that as x and y increase, the amount of Mn dissolved increases, and the cycle capacity retention gradually decreases. When 0 < x ≤ 0.3 and 0 < y ≤ 0.3, the IC value can be maintained within the range of 0-8%, the amount of Mn dissolved is less than or equal to 739 μg / g, and the cycle capacity retention after 200 cycles is above 86.6%. Preferably, when 0 < x ≤ 0.2 and 0 < y ≤ 0.2, the amount of manganese deposited on the negative electrode is less, and the cycle capacity retention is higher.

[0212] As can be seen from Table 5, the chemical formula of the positive electrode active material in Example 21 may also include G and T elements, the amount of manganese deposited on the negative electrode sheet is less, and the cycle capacity retention rate is higher.

[0213] As can be seen from Tables 5 and 1, based on Examples 1, 22 and 23, by setting a manganese scavenger, the amount of Mn leached to the negative electrode can be effectively reduced, the damage to the SEI film of the negative electrode can be reduced, and the cycle capacity retention rate can be improved.

[0214] The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A lithium-ion secondary battery, characterized in that, It includes a positive electrode, a negative electrode, and an electrolyte; the positive electrode includes a positive active material layer, the positive active material layer includes a positive active material, and the positive active material includes lithium nickel manganese oxide containing a non-nickel manganese trivalent metal element. The crystal structure of the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes a spinel-type structure. The lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Li b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k- q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is the non-nickel-manganese trivalent metal element, the ionic radius of M is in the range of 33 pm to 90 pm, G includes a +1 valence metal element and / or a +2 valence metal element, T includes one or more of +4, +5, and +6 valence elements, Q includes one or more of F, Cl, Br, I, S, and N, 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, 0 ≤ q ≤ 0.5; and x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, -0.03 ≤ xy ≤ 0.

03.

2. The lithium-ion secondary battery according to claim 1, characterized in that, The M includes one or more of Al, Sc, Cr, Fe, Co, Ga, Y, Nb, Ru, Rh, In, Ho, Er, Tm, Yb, Lu, and Os.

3. The lithium-ion secondary battery according to claim 1 or 2, characterized in that, The ionic radius of M is in the range of 53 pm to 70 pm.

4. The lithium-ion secondary battery according to claim 1 or 2, characterized in that, The M includes one or more of Sc, Cr, Fe, Co, Ga, and Rh.

5. The lithium-ion secondary battery according to claim 1, characterized in that, When the positive electrode is in a fully discharged state, the active Mn in the positive electrode is... 3+ The molar ratio with active lithium is 0~8%.

6. The lithium-ion secondary battery according to claim 1 or 2, characterized in that, When the positive electrode is in a fully discharged state, the active Mn in the positive electrode is... 3+ The molar ratio with active lithium is 0~5%.

7. The lithium-ion secondary battery according to claim 1, 2, or 5, characterized in that, -0.03≤(x+g)-(y+t)≤0.03, 0<x+g≤0.

25.

8. The lithium-ion secondary battery according to claim 1, 2, or 5, characterized in that, G includes +2 valent metals with ionic radii of 49 pm to 89 pm; and / or, T includes +4, +5, and +6 valent metals with ionic radii of 33 pm to 73 pm, and / or, 0 < y + t ≤ 0.

2.

9. The lithium-ion secondary battery according to claim 1, 2, or 5, characterized in that, G includes one or more of Mg, Cu, and Zn, and / or T includes one or more of Si, P, Ti, V, Ge, As, Se, Zr, Nb, Mo, Sn, Sb, Te, Ta, and W; and / or, 0 < y + t ≤ 0.1; and / or, 0.01≤x≤0.1。 10. The lithium-ion secondary battery according to claim 1, 2, or 5, characterized in that, The lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Mn. 3+ Mn 3+ The proportion IM of the total Mn satisfies 0 ≤ IM ≤ 5%.

11. The lithium-ion secondary battery according to claim 1, 2, or 5, characterized in that, The lithium-ion secondary battery includes a manganese scavenger, which coats and / or adheres to the surface of the lithium nickel manganese oxide particles containing non-nickel manganese trivalent metal elements; and / or, the manganese scavenger is located on the surface of the positive electrode active material layer. And / or, the manganese scavenger is located on the surface of the secondary battery separator; and / or, the manganese scavenger is located on the surface of the negative electrode active material layer of the negative electrode sheet.

12. The lithium-ion secondary battery according to claim 11, characterized in that, The manganese scavenger comprises one or more of the following: substances containing polyoxoanionic groups, lithium-rich substances, and adsorbent substances, wherein the specific surface area of ​​the adsorbent substance is greater than or equal to 100. 2 / g, and less than or equal to 3000m 2 / g; The polyoxoanionic group material includes one or more of lithium phosphate, lithium hydrogen phosphate, lithium dihydrogen phosphate, lithium silicate, lithium sulfate, lithium polyacrylate, and lithium carbonate; and / or, The lithium-rich substances include one or more of LiNiO2, Li5FeO4, Li2MnO3, Li6CoO4, Li2CuO2, Li2MoO2, Li5ReO6, Li2O, Li2O2, and Li2S; and / or, The adsorbent material includes one or more of activated carbon, carbon nanotubes, and zeolite.

13. A positive electrode active material, characterized in that, The positive electrode active material includes lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements. The crystal structure of the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes a spinel-type structure. The lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Li b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k- q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is the non-nickel-manganese trivalent metal element, the ionic radius of M is in the range of 33 pm to 90 pm, G includes a +1 valence metal element and / or a +2 valence metal element, T includes one or more of +4, +5, and +6 valence elements, Q includes one or more of F, Cl, Br, I, S, and N, 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, 0 ≤ q ≤ 0.5; and x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, -0.03 ≤ xy ≤ 0.

03.

14. A method for preparing a positive electrode active material, characterized in that, include: A lithium salt, a nickel source, a manganese source, and a dopant source are mixed and calcined at a first temperature for a first time to form an intermediate product. The first temperature is 600℃~1200℃, and the first time is 1h~50h. The dopant source includes a non-nickel manganese trivalent metal source, or the dopant source includes a non-nickel manganese trivalent metal source and also includes one or more of A source, G source, T source, and Q source. The A source includes one or more of Na source, K source, Rb source, and Cs source. The G source includes a +1 valence metal source and / or a +2 valence metal source. The T source includes raw materials containing +4, +5, and +6 valence elements. The Q source includes one or more of F source, Cl source, Br source, I source, S source, and N source. The intermediate product is kept at a second temperature for a second time to form a positive electrode active material, wherein the second temperature is 500℃~850℃ and the second time is 1h~50h. The positive electrode active material includes lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements, and the crystal structure of the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes a spinel structure; the lithium nickel manganese oxide containing non-nickel manganese trivalent metal elements includes Li b A a Ni 0.5-x-g Mn 1.5-y-t M x+y G g T t O 4-k- q Q q Wherein, A includes one or more of Na, K, Rb, and Cs; M is the non-nickel-manganese trivalent metal element, the ionic radius of M is in the range of 33 pm to 90 pm, G includes a +1 valence metal element and / or a +2 valence metal element, T includes one or more of +4, +5, and +6 valence elements, Q includes one or more of F, Cl, Br, I, S, and N, 0 < b ≤ 2.2, 0 ≤ a ≤ 0.5, 0 < b + a ≤ 2.2, 0 ≤ g ≤ 0.1, 0 ≤ t ≤ 0.1, -0.1 ≤ k ≤ 0.3, 0 ≤ q ≤ 0.5; and x and y must satisfy the following characteristics: 0 < x ≤ 0.2, 0 < y ≤ 0.2, -0.03 ≤ xy ≤ 0.

03.

15. An electrical appliance, characterized in that, Includes the lithium-ion secondary battery according to any one of claims 1-12, and / or the positive electrode active material according to claim 13, and / or the positive electrode active material prepared by the preparation method according to claim 14.

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