Secondary battery and electric device

Abstract

The embodiment of the invention provides a secondary battery and an electric device. The secondary battery comprises a positive pole piece, the positive pole piece comprises a positive current collector and a positive film layer, the positive film layer is arranged on at least one side of the positive current collector, the positive film layer comprises a first oxide, the first oxide comprises an MOy group, y is greater than or equal to 3, and M is at least one element in IVA, VA, VIA, IVB, VB and VIB groups and has a valence state greater than or equal to + 4. According to the technical scheme, the cycle performance and the storage performance of the secondary battery can be improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a secondary battery and an electrical device. Background Technology

[0002] With increasing environmental pollution, the new energy industry is attracting more and more attention. Within the new energy industry, battery technology is a crucial factor in its development.

[0003] The development of battery technology requires consideration of various design factors, such as energy density, cycle life, capacity, fast charging performance, and reliability. Therefore, improving the cycle performance and storage performance of batteries is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a secondary battery and power supply device with long cycle performance and storage performance.

[0005] To achieve the above objectives, this application provides a secondary battery and an electrical device.

[0006] In a first aspect, a secondary battery is provided, comprising a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode film layer, the positive electrode film layer being disposed on at least one side of the positive current collector, the positive electrode film layer including a first oxide; wherein, the first oxide includes MO y A group, y≥3, where M is an element with a valence greater than or equal to +4 and is at least one element in group IVA, VA, VIA, IVB, VB, or VIB.

[0007] In the embodiments of this application, the positive electrode film layer includes a first oxide, and the first oxide includes MO. y Wherein, M is at least one element from Groups IVA, VA, VIA, IVB, VB, and VIB with a valence state of not less than +4. Oxides formed from high-valence M exhibit structural stability, acid resistance, and corrosion resistance. Their use in positive electrode films can reduce the impact of H... + The generation of this corrosion on the positive electrode active material can improve the cycle performance and storage performance of the secondary battery.

[0008] In one possible implementation, M includes at least one of Te, Zr, Nb, Ta, Mo, and W.

[0009] In the embodiments of this application, by selecting M from one or more of Te, Zr, Nb, Ta, Mo, and W, MO can be made... y It has better acid and corrosion resistance, which is beneficial for further reducing the impact of H. +The generation of this corrosion on the positive electrode active material can improve the cycle performance of the secondary battery.

[0010] In one possible implementation, the pH of the first oxide... 1 Satisfy: pH 1 ≥10.

[0011] In this embodiment, the positive electrode film layer includes a first oxide, and the first oxide includes an acid- and corrosion-resistant MO. y It can be used to balance the acidic H+ produced in the positive electrode. + Therefore, by ensuring that the pH of the first oxide is not less than 10, that is, by making the first oxide alkaline, the acidic H₂ can be effectively neutralized. + .

[0012] In one possible implementation, the pH of the first oxide... 1 Satisfy: 11 ≤ pH 1 ≤13.

[0013] In this embodiment, by setting the pH value of the first oxide to 11-13, it is beneficial to further balance the acidic H+ generated in the positive electrode. + .

[0014] In one possible implementation, when the secondary battery is discharged to less than or equal to 2V, the pH of the positive electrode film... 2 Satisfy: pH 2 ≥10.

[0015] In this embodiment of the application, during the continuous charge-discharge cycle of the battery, the electrolyte also undergoes continuous oxidative decomposition reaction, resulting in the continuous generation of byproduct H. + This can lead to continuous corrosion of the positive electrode active material. By adding structurally stable, acid- and corrosion-resistant MO to the positive electrode film layer... y This can reduce the possibility of corrosion of the positive electrode active material; furthermore, by ensuring that the pH value of the positive electrode film is not less than 10 when the secondary battery is discharged to less than or equal to 2V, the positive electrode film itself can be in a strong alkaline state to neutralize the acid generated by the high potential on the positive electrode side, prevent the acid from diffusing to other parts of the secondary battery and consuming active lithium, thereby improving the performance of the secondary battery.

[0016] In one possible implementation, when the secondary battery is discharged to less than or equal to 2V, the pH of the positive electrode film... 2 Satisfies: 10.5 ≤ pH 2 ≤12.

[0017] In this embodiment, by maintaining the pH value of the positive electrode film between 10.5 and 12, the positive electrode film can be in a better alkaline state to neutralize the acid generated subsequently, thereby further improving the cycle performance of the battery.

[0018] In one possible implementation, the positive electrode film layer further includes a positive electrode active material; the mass ratio D of M to the positive electrode active material satisfies: 0.001≤D≤0.1.

[0019] In this embodiment of the application, by keeping the mass ratio D of M to the positive electrode active material between 0.001 and 0.1, MO can be made... y Lowering acidic H + The effect on the positive electrode is to improve the cycle performance and storage performance of the battery, while also taking into account the energy density of the battery.

[0020] In one possible implementation, the Dv50 of the first oxide satisfies: Dv50≤10μm.

[0021] In this embodiment of the application, by ensuring that the Dv50 of the first oxide is not greater than 10 μm, the first oxide can be uniformly mixed with the positive electrode active material, that is, uniformly dispersed in the positive electrode film layer.

[0022] In one possible implementation, the Dv50 of the first oxide satisfies: Dv50≤1μm.

[0023] In this embodiment of the application, by ensuring that the Dv50 of the first oxide is not greater than 1 μm, it helps to make the first oxide more uniformly dispersed in the positive electrode film.

[0024] In one possible implementation, the Dv50 of the first oxide satisfies: Dv50 ≤ 100 nm.

[0025] In this embodiment of the application, by ensuring that the Dv50 of the first oxide is no greater than 100 nm, it helps to further improve the uniformity of the dispersion of the first oxide in the positive electrode film.

[0026] In one possible implementation, the first oxide is distributed on the surface of the positive electrode active material.

[0027] In the embodiments of this application, MO is structurally stable and resistant to acid and corrosion. y It is added to the positive electrode film to protect the positive electrode active material from acid corrosion. By distributing the first oxide on the surface of the positive electrode active material, that is, by uniformly and densely coating the positive electrode active material particles, the positive electrode active material can be better protected, which is beneficial to further improving the cycle performance of the battery.

[0028] In one possible implementation, the first oxide satisfies: A x MO y , x≥2; where A includes alkali metal elements and at least one element from Group IIA.

[0029] In this embodiment, the first oxide is used to neutralize the acidic H₂ generated in the positive electrode. + Therefore, the first oxide must be alkaline. By including alkaline elements in the first oxide, it is beneficial to further improve the acid resistance of the positive electrode film, thereby further improving the battery's storage performance and cycle performance.

[0030] In one possible implementation, the secondary battery is a lithium-ion secondary battery, and the first oxide includes Li. x MO y , x≥2.

[0031] In this embodiment of the application, when the secondary battery is a lithium-ion secondary battery, the first oxide includes Li x MO y In this way, the first oxide can not only protect the positive electrode active material from corrosion by acidic substances, but also replenish active lithium, which is beneficial to further improve the cycle performance of the battery.

[0032] In one possible implementation, the positive electrode active material includes M and Mn.

[0033] In this embodiment, on the one hand, manganese-containing materials have high thermal stability, which is beneficial to improving the safety performance of the battery; on the other hand, by also doping M into the positive electrode active material, it is beneficial to increase the MO content. y The coating effect of the first oxide on the positive electrode active material.

[0034] In one possible implementation, the mass content of Mn in the positive electrode active material is greater than or equal to 20%.

[0035] In this embodiment of the application, by ensuring that the mass content of Mn in the positive electrode active material is not less than 20%, the safety performance of the battery can be further improved.

[0036] In one possible implementation, the structure of the positive electrode active material includes a spinel structure.

[0037] In this embodiment, the spinel structure has a relatively stable structure, high safety performance and high energy density. By using a positive electrode active material with a spinel structure in the battery, the overall performance of the battery can be further improved.

[0038] In one possible implementation, the positive electrode active material includes Li 1+t Mea N b Mn 2-a-b O 4-k G g -0.1≤t≤2.2, 0.2≤a≤1.0, 0≤b≤0.3, 0.2≤a+b≤1, -0.1≤k≤0.3, 0≤g≤0.1; Me includes at least one of Cr, Fe, Co, Ni, Cu; N includes at least one of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Zn, Ag, Cd, lanthanides, and the M element; G includes at least one of F, Cl, Br, I.

[0039] In this embodiment, the spinel-structured manganese-rich material has higher structural stability and higher average charge-discharge voltage. Therefore, using the spinel-structured manganese-rich material as the positive electrode active material of the secondary battery is beneficial to further improve the performance of the secondary battery.

[0040] In one possible implementation, Me includes Ni.

[0041] In this embodiment of the application, incorporating Ni into the positive electrode active material is beneficial to improving the battery capacity and the structural and thermal stability of the bulk phase, thereby extending the battery's cycle performance.

[0042] In one possible implementation, the Me includes Me 1 and Me 2 The Me 1 Including Ni, the Me 2 It includes at least one of Cr, Fe, Co, and Cu.

[0043] In this embodiment of the application, incorporating multiple transition metals into the positive electrode active material can improve the overall performance of the secondary battery.

[0044] In a second aspect, an electrical device is provided, comprising a secondary battery as described in the first aspect and any possible implementation thereof. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the structure of a positive electrode sheet according to an embodiment of this application;

[0047] Figure 2This is a schematic diagram of a secondary battery according to an embodiment of this application;

[0048] Figure 3 This is a schematic diagram of a battery according to an embodiment of this application;

[0049] Figure 4 This is a schematic diagram of an electrical device according to an embodiment of this application;

[0050] Figure 5 This is a schematic diagram of an electrical device according to an embodiment of this application;

[0051] Figure 6 This is a SEM image of the positive electrode film layer according to one embodiment of this application. Detailed Implementation

[0052] Embodiments of the secondary battery and power-consuming device of this application have been described in detail with appropriate reference to the accompanying drawings, but 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0053] 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.

[0054] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0055] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0056] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0057] The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, charge / discharge efficiency, reliability, storage performance, and first-charge capacity. Among these, manganese-based spinel materials are receiving increasing attention due to their high thermal stability, low cost, and high safety. However, manganese-based spinel materials have a high average charge / discharge voltage (vs. Li / Li). + Therefore, the potential on the positive electrode side is high during operation, which results in the generation of acidic H+. + H, which is acidic + It can corrode manganese-based materials, severely impacting battery performance and lifespan. Therefore, improving battery performance is a pressing technical challenge when spinel-structured manganese-containing materials are used as positive electrode active materials.

[0058] In view of this, embodiments of this application provide a secondary battery and an electrical device. The secondary battery includes a positive electrode current collector and a positive electrode film layer, the positive electrode film layer including a first oxide, the first oxide including MO. y y≥3, M is an element with a valence greater than or equal to +4 and is at least one element in the families IVA, VA, VIA, IVB, VB, and VIB. MO y It possesses stable structure, acid resistance, and corrosion resistance; incorporating it into the positive electrode film can reduce the impact of H. + The generation of this corrosion on the positive electrode active material improves the cycle performance of the secondary battery.

[0059] During the charging process of a secondary battery, lithium ions are released from the positive electrode active material, move and embed into the negative electrode; while during the discharging process, they move and embed into the positive electrode active material.

[0060] It should be understood that the “intercalation” process described in this application refers to the process by which lithium ions are intercalated into the positive electrode active material or the negative electrode due to an electrochemical reaction, and the “extraction” and “deintercalation” processes described in this application refer to the process by which lithium ions are extracted from the positive electrode active material or the negative electrode due to an electrochemical reaction.

[0061] In this application's embodiments, the secondary battery can refer to the smallest structural unit of a battery. Multiple secondary batteries can first be assembled into a battery module, and then the battery module can be assembled into a battery; multiple secondary batteries can also be directly assembled into a battery.

[0062] [Rechargeable Battery]

[0063] This application provides a secondary battery, including a positive electrode.

[0064] Figure 1 This is a schematic diagram of the structure of the positive electrode sheet according to one embodiment of this application. Figure 1 As shown, the positive electrode 1 includes a positive current collector 10 and a positive electrode film 11, with the positive electrode film 11 disposed on at least one side of the positive current collector 10.

[0065] The positive electrode film layer 11 has two opposing surfaces along its thickness direction. The positive electrode film layer 11 can be disposed on one surface of the positive electrode current collector 10, or on both surfaces of the positive electrode current collector 10. As an example, such as... Figure 1 As shown, the positive electrode film layer 11 is disposed on both sides of the positive electrode current collector 10.

[0066] The positive electrode film 11 includes a first oxide, which includes MO. y y≥3, M is an element with a valence greater than or equal to +4 and is at least one element in the family IVA, VA, VIA, IVB, VB, VIB.

[0067] It should be understood that MO y This refers to a group that can have different valence states to be represented as an ion, such as NbO4. 3- Zr4 2- It can also be in the form of compounds such as SiO2.

[0068] MO y The oxidation state of M in the atom is not less than +4. The oxides formed by such high oxidation state elements have the property of structural stability. This is because when M is in a high oxidation state, the outermost electron pairs are more tightly bound to the atomic nucleus, which makes them exhibit very low activity in external chemical reactions, including acids, thus reducing their possibility of participating in further chemical reactions.

[0069] MO yIt possesses acid and corrosion resistance because: oxides formed from high-valence elements have strong ionic or covalent bonds. These ionic or covalent bonds have high bond energies and are not easily corroded by acidic H+. + Damaged by other corrosive substances; in addition, MO y It has a dense crystal structure, which can effectively block the penetration of corrosive media, thus protecting the internal materials from corrosion.

[0070] It should be noted here that acid resistance, corrosion resistance, and stability are characteristics of MO. y The properties of the group are not related to the presence of MO. y Properties of the first oxide of the group.

[0071] When the electrolyte produces corrosive H₂ due to the oxidation and reduction of the positive electrode material... + When lithium metal or sodium metal (or other metals) is deposited on the negative electrode side, H + This will corrode the metal, leading to the consumption of active metals and severely impacting battery life. Therefore, introducing MO into the positive electrode active material... y The first oxide of the group can reduce H + Corrosion of the positive electrode active material.

[0072] In the above scheme, the positive electrode film 11 includes a first oxide, and the first oxide includes MO. y Wherein, M is at least one element from Groups IVA, VA, VIA, IVB, VB, and VIB with a valence state of not less than +4. The oxides formed by M in high valence states possess structural stability, acid resistance, and corrosion resistance. Using them in the positive electrode film layer 11 can reduce the impact of H... + The generation of this corrosion on the positive electrode active material can improve the cycle performance and storage performance of the secondary battery.

[0073] Specifically, the price state of M can be +4, +5, +6, or any value within the above range.

[0074] Specifically, MO y It can be MO y 3- MO y 2- Or other valence states.

[0075] It should be noted that the above mechanism is only used to explain why the positive electrode film 11 in the secondary battery tends to be stable, and is not a limitation on the secondary battery.

[0076] In some implementations, M includes at least one of Te, Zr, Nb, Ta, Mo, and W.

[0077] In the above scheme, by selecting M from one or more of Te, Zr, Nb, Ta, Mo, and W, MO can be made... y It has better acid and corrosion resistance, which is beneficial for further reducing the impact of H. + The generation of this corrosion on the positive electrode active material can improve the cycle performance of the secondary battery.

[0078] In some embodiments, the pH of the first oxide 1 Satisfy: pH 1 ≥10.

[0079] MO in the first oxide y The group is used to neutralize the acidic H. + Therefore, the first oxide must be alkaline in order to neutralize the acid.

[0080] In the above scheme, the positive electrode film layer 11 includes a first oxide, which includes an acid- and corrosion-resistant MO. y It can be used to balance the acidic H+ produced in the positive electrode. + Therefore, by ensuring that the pH of the first oxide is not less than 10, that is, by making the first oxide alkaline, the acidic H+ can be effectively neutralized. + .

[0081] Specifically, the pH value of the first oxide can be 10, 10.5, 10.8, 11, 12, 13 or any value within the above range.

[0082] It should be noted here that the pH in the embodiments of this application... 1 In order to match the pH below 2 It is used to distinguish between different substances and has no other meaning.

[0083] In some embodiments, the pH of the first oxide 1 Satisfy: 11 ≤ pH 1 ≤13.

[0084] In the above scheme, by setting the pH value of the first oxide to 11-13, it is beneficial to further balance the acidic H+ generated in the positive electrode. + .

[0085] In some embodiments, when the secondary battery is discharged to less than or equal to 2V, the pH of the positive electrode film 11 is... 2 Satisfy: pH 2 ≥10.

[0086] It should be understood that ≤2V mentioned here refers to the potential difference between the positive and negative electrodes of the secondary battery being ≤2V.

[0087] When the potential difference between the positive and negative electrodes of the secondary battery is ≤2V, most of the Li will return to the positive electrode. At this time, the pH of the positive electrode film 11 can more accurately represent the pH of the positive electrode active material after the electric cycle.

[0088] In the above scheme, during the continuous charge-discharge cycle of the secondary battery, the electrolyte also undergoes continuous oxidative decomposition reactions, resulting in the continuous generation of by-product H ions, which leads to the continuous corrosion of the positive electrode material. By adding structurally stable, acid- and corrosion-resistant MO to the positive electrode film layer 11... y This can reduce the possibility of corrosion of the positive electrode active material; furthermore, by ensuring that the pH of the positive electrode film 11 is not less than 10 when the secondary battery is discharged to ≤2V, the positive electrode film 11 itself can be in a strong alkaline state to neutralize the acid generated by the high potential on the positive electrode side, and prevent the acid from diffusing to other parts of the secondary battery and consuming the active lithium, thereby improving the performance of the secondary battery.

[0089] Specifically, when the secondary battery is discharged to ≤2V, the pH of the positive electrode film 11 can be 10, 10.5, 10.8, 11, 11.2, 12, 12.5, 13 or any value within the above range.

[0090] In some embodiments, when the secondary battery is discharged to less than or equal to 2V, the pH of the positive electrode film 11 is... 2 Satisfies: 10.5 ≤ pH 2 ≤12.

[0091] In the above scheme, by maintaining the pH of the positive electrode film 11 between 10.5 and 12, the positive electrode film 11 can be in a better alkaline state to neutralize the acid generated subsequently, thereby further improving the cycle performance of the battery.

[0092] In some embodiments, the positive electrode film 11 further includes a positive electrode active material; the mass ratio D of M to the positive electrode active material satisfies: 0.001≤D≤0.1.

[0093] Adding MO into the positive electrode film layer 11 y The first oxide of the group can neutralize the H generated by the battery at high potential. + The content of positive electrode active material in the positive electrode film layer 11 affects the energy density and other performance of the battery.

[0094] In the above scheme, by ensuring that the mass ratio D of M to the positive electrode active material in the positive electrode film layer 11 satisfies: 0.001 ≤ D ≤ 0.1, MO can be optimized. y Lowering acidic H + The effect on the positive electrode is to improve the cycle performance and storage performance of the battery, while also taking into account the energy density of the battery.

[0095] Specifically, the mass ratio D of M to the positive electrode active material can be 0.001, 0.005, 0.01, 0.05, 0.08, 0.1 or any value within the above range.

[0096] In some embodiments, the Dv50 of the first oxide satisfies: Dv50≤10μm.

[0097] Dv50 can refer to the particle size at which the cumulative particle size distribution number of a sample reaches 50%, meaning that 50% of the particles are smaller than Dv50.

[0098] In the above scheme, by ensuring that the Dv50 of the first oxide is no greater than 10 μm, the first oxide can be uniformly mixed with the positive electrode active material, that is, uniformly dispersed in the positive electrode film layer.

[0099] Specifically, the Dv50 of the first oxide can be 10 μm, 9.2 μm, 9 μm, 5 μm, 1 μm, 100 nm or any value within the above range.

[0100] In one possible implementation, the Dv50 of the first oxide satisfies: Dv50≤1μm.

[0101] In this embodiment of the application, by ensuring that the Dv50 of the first oxide is not greater than 1 μm, it helps to make the first oxide more uniformly dispersed in the positive electrode film.

[0102] In one possible implementation, the Dv50 of the first oxide satisfies: Dv50 ≤ 100 nm.

[0103] In this embodiment of the application, by ensuring that the Dv50 of the first oxide is no greater than 100 nm, it helps to further improve the uniformity of the dispersion of the first oxide in the positive electrode film.

[0104] In some embodiments, the first oxide is distributed on the surface of the positive electrode active material.

[0105] In the above scheme, MO is structurally stable and resistant to acid and corrosion. y It is added to the positive electrode film layer 11 to protect the positive electrode active material from acid corrosion. By distributing the first oxide on the surface of the positive electrode active material, that is, by uniformly and densely coating the positive electrode active material particles, the positive electrode active material can be better protected, which is beneficial to further improving the cycle performance of the battery.

[0106] Specifically, this application does not impose any particular limitation on the specific morphology of the first oxide distributed on the surface of the positive electrode active material. It can be an irregular island-like coating or a regular sheet-like or layered coating.

[0107] It should be noted that the first oxide can be incorporated into the positive electrode film 11 in the form of a coating, or it can be directly mixed with the positive electrode active material. This application does not make any specific limitations on this.

[0108] In some embodiments, the first oxide satisfies: A x MO y , x≥2; where A includes alkali metal elements and at least one element from Group IIA.

[0109] In the above scheme, the first oxide is used to neutralize the acidic H generated in the positive electrode 1. + Therefore, the first oxide needs to be alkaline. By including alkaline elements in the first oxide, it is beneficial to further improve the acid resistance of the positive electrode film 11, thereby further improving the battery's storage performance and cycle performance.

[0110] Specifically, the element represented by A generally remains consistent with the system of the secondary battery. For example, in a lithium secondary battery, A can be Li, in a sodium secondary battery, A can be Na, and so on.

[0111] In some embodiments, the secondary battery is a lithium-ion secondary battery, and the first oxide includes Li. x MO y , x≥2.

[0112] In the above scheme, when the secondary battery is a lithium-ion secondary battery, the first oxide includes Li x MO y In this way, the first oxide can not only protect the positive electrode active material from corrosion by acidic substances, but also replenish active lithium, which is beneficial to further improve the cycle performance of the battery.

[0113] Specifically, Li x MO y It can be Li2TeO3, Li4Ta2O7, Li2ZrO3, Li 14 Mo2O 13 Or other substances.

[0114] In some implementations, the range of x satisfies: 2≤x≤8, 3≤y≤7.

[0115] It should be noted that during the charging and discharging process of the battery, Li undergoes insertion / extraction and consumption, resulting in different molar contents of Li at different discharge states. In the examples of positive electrode active materials in this application, the molar contents of Li refer to the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to the battery system, the molar contents of Li will change after charge-discharge cycles.

[0116] Similarly, in the examples of positive electrode active materials in the embodiments of this application, the molar content of O is only a theoretical state value. The release of oxygen from the crystal lattice will cause the molar content of oxygen to change. In the actual charging and discharging process of the battery, the molar content of O will fluctuate.

[0117] In some embodiments, the positive electrode active material includes M and Mn.

[0118] As mentioned above, manganese-containing materials have attracted increasing attention due to their high thermal stability and low cost. Furthermore, the development and processing of manganese-based materials have a relatively small environmental impact and are considered environmentally friendly.

[0119] In the above scheme, on the one hand, manganese-containing materials have high thermal stability, which is beneficial to improving the safety performance of the battery; on the other hand, by also doping M into the positive electrode active material, it is beneficial to increase the MO content. y The coating effect of the first oxide on the positive electrode active material.

[0120] In some embodiments, the mass content of Mn in the positive electrode active material is greater than or equal to 20%.

[0121] In the above scheme, by ensuring that the mass content of Mn in the positive electrode active material is not less than 20%, the safety performance of the secondary battery can be further improved.

[0122] Specifically, the mass content of Mn in the positive electrode active material can be 20%, 25%, 30%, 40%, 48%, 55%, or any value within the above range.

[0123] In some embodiments, the structure of the positive electrode active material includes a spinel structure.

[0124] In the above scheme, the spinel structure has a relatively stable structure, high safety performance and high energy density. By using positive electrode active materials with spinel structure in the battery, the overall performance of the battery can be further improved.

[0125] In one possible implementation, the positive electrode active material includes Li 1+t Me a N b Mn 2-a-b O 4-k G g -0.1≤t≤2.2, 0.2≤a≤1.0, 0≤b≤0.3, 0.2≤a+b≤1, -0.1≤k≤0.3, 0≤g≤0.1; Me includes at least one of Cr, Fe, Co, Ni, and Cu; N includes at least one of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Zn, Ag, Cd, lanthanides, and M; G includes at least one of F, Cl, Br, and I.

[0126] The aforementioned positive electrode active material is a manganese-based material with a spinel structure. In this crystal structure, cations are arranged in a cubic close-packed configuration, with divalent cations filling one-eighth of the tetrahedral voids and trivalent cations filling one-half of the octahedral voids.

[0127] It should be noted that Me includes at least one of Cr, Fe, Co, Ni, and Cu. N includes at least one of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Zn, Ag, and Cd, or at least one of the lanthanides, or at least one of the M elements mentioned above; G includes at least one of F, Cl, Br, and I.

[0128] Including multiple transition metals, such as manganese and nickel, or manganese and aluminum, in the positive electrode active material of secondary batteries can balance the overall performance of the battery. Different transition metals have different properties, and a balance between cost and performance can be found by adjusting different metal ratios. For example, manganese-based materials have the advantages of low cost and high thermal stability, while nickel-based materials have high energy density, high capacity, and high operating voltage. By combining these two in secondary batteries, various aspects of battery performance can be considered.

[0129] Furthermore, in spinel-structured cathode active materials, Me in this structure can achieve valence change to realize capacity, and the average charge-discharge voltage is higher than that of Mn. 3+ or Mn 4+ The higher the energy density, the higher the energy density. In addition, because the Me site and Mn site are highly compatible, they can be interspersed with each other, which leads to a significant increase in entropy, making the structure more stable.

[0130] In the above scheme, the spinel-structured manganese-rich material has higher structural stability and higher average charge and discharge voltage. Therefore, using the spinel-structured manganese-rich material as the positive electrode active material of the secondary battery is beneficial to further improve the performance of the secondary battery.

[0131] In some implementations, Me includes Ni.

[0132] Nickel-based materials offer several advantages when used as cathode active materials: First, nickel-containing cathode active materials can achieve higher voltage and greater capacity, thereby increasing the overall energy density of the battery. This means that the battery can store more energy in the same volume or weight. Second, nickel is also an abundant and inexpensive raw material, and adding nickel to cathode active materials also helps reduce battery production costs. Finally, nickel-based materials can also provide higher power density, making them suitable for applications requiring rapid charging and discharging, such as the powertrain systems of electric vehicles.

[0133] In the above scheme, the presence of Ni increases the active sites of the positive electrode active material, thereby increasing the energy density of the battery. Therefore, by ensuring that Me includes Ni, the performance of the battery can be further improved.

[0134] In some implementations, Me includes Me 1 and Me 2 Me 1 Including Ni, Me 2 It includes at least one of Cr, Fe, Co, and Cu.

[0135] In the above scheme, incorporating multiple transition metals into the positive electrode active material can improve the overall performance of the secondary battery.

[0136] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. The secondary battery can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, a magnesium-ion battery, etc.

[0137] Figure 2 This is a schematic diagram of a secondary battery according to one embodiment of this application. For example, such as... Figure 2 As shown, the secondary battery 3 is a square secondary battery. The secondary battery 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed in the housing 31.

[0138] The electrode assembly 33 can be made from a positive electrode, a negative electrode, and a separator through a winding process or a stacking process.

[0139] End cap assembly 32 includes electrode terminals 322, such as Figure 2 As shown, the end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal.

[0140] The secondary battery 3 also includes a current collector 34, which is used to connect the tab 331 and the electrode terminal 322 of the electrode assembly 33. For example, in the case that the electrode 1 in this embodiment is a positive electrode, one current collector 34 is used to connect the tab and the positive electrode terminal of the positive electrode, and another current collector 34 is used to connect the tab and the negative electrode terminal of the negative electrode.

[0141] In some embodiments, the secondary battery 3 includes an electrode assembly 33, which includes an electrode assembly body 330 and tabs 331 extending from the electrode assembly body 330.

[0142] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0143] [Positive electrode plate]

[0144] The positive electrode current collector 10 can be a metal foil or a composite positive electrode current collector. For example, the positive electrode current collector can be an aluminum foil.

[0145] The composite positive electrode 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 positive electrode current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0146] The positive electrode film layer 11 may also optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0147] The positive electrode film 11 may optionally include a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0148] [Negative electrode plate]

[0149] The negative electrode includes a negative current collector and a negative electrode film layer disposed on the negative current collector.

[0150] The negative electrode current collector can be a metal foil or a composite negative electrode current collector. The negative electrode current collector can be copper foil. Composite negative electrode current collectors can be formed by depositing metallic materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0151] The negative electrode film layer includes a negative electrode active material. The negative electrode active material can be any negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from one or more 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.

[0152] The negative electrode film layer may also optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0153] The negative electrode film may optionally include a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0154] [Electrolytes]

[0155] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0156] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0157] Electrolyte salts may include one or more 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.

[0158] Solvents may include one or more of the following: 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.

[0159] The electrolyte may also optionally include negative electrode film-forming additives, positive electrode film-forming additives, and performance additives that can improve certain battery performance, such as performance additives that improve battery overcharge performance, battery high temperature or low temperature performance, etc.

[0160] [Isolation membrane]

[0161] The separator is used to separate the positive electrode and the negative electrode. 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.

[0162] The material of the separator can be selected from one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film; there are no particular restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different; there are no particular restrictions.

[0163] Positive electrode, negative electrode and separator can be made into electrode assembly by winding process or stacking process.

[0164] [Battery]

[0165] This application provides a battery, including the secondary battery 3 in the above embodiments. The secondary battery 3 can be a secondary battery 3 after formation and aging processes. Figure 3 This is a schematic diagram of a battery according to an embodiment of this application. Figure 3 As shown, battery 5 may include multiple secondary batteries 3 (not shown in the figure).

[0166] The secondary battery 3 can be directly assembled into battery 5, or it can be assembled into a battery module first, and then multiple battery modules can be assembled into battery 5.

[0167] [Electrical appliances]

[0168] This application provides an electrical device, including the battery described in the above embodiments.

[0169] In some embodiments, the electrical device includes an energy storage device or a heavy-duty truck. Energy storage devices and heavy-duty trucks have high requirements for the lifespan and long-term cycle performance of the secondary battery 3. Applying the secondary battery 3 to the above-mentioned electrical device can improve the lifespan of the electrical device.

[0170] Electrical devices can also be lighting devices, spacecraft, etc., and the embodiments of this application include, but are not limited to, these.

[0171] Figure 4 This is a schematic diagram of an electrical device according to an embodiment of this application. Figure 4As shown, this application provides an electrical device, which is a heavy-duty truck 6. The battery in the heavy-duty truck 6 can be replaced by a battery swapping device to replace the battery with insufficient power with a fully charged battery.

[0172] Figure 5 This is a schematic diagram of an electrical device according to an embodiment of this application. Figure 5 As shown, this application provides an electrical device, which is an energy storage device 7, and the energy storage device 7 may include multiple batteries 5. The energy storage device 7 can be applied to a power storage station to store and release electrical energy.

[0173] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0174] [Examples and Comparative Examples]

[0175] Example 1

[0176] (1) Preparation of positive electrode sheet

[0177] (1.1) Preparation of positive electrode active material: Li source, Ni source, and Mn source were mixed uniformly in a molar ratio of Li:Ni:Mn = 1:0.5:1.5. Then, the mixture was heated to 980℃ in an air or oxygen atmosphere and held for 10 h, followed by cooling to 700℃ and holding for 5 h to obtain the positive electrode active material Li. 1.01 Ni 0.5 Mn 1.5 O 3.98 .

[0178] (1.2) Mixing of positive electrode active material and first oxide: The positive electrode active material prepared in step 1.1 and the first oxide Li2NbO4 are mixed evenly, and then heated to 300℃ and kept at that temperature for 10h in an air atmosphere; wherein, the mass ratio D of M (i.e. Nb) to positive electrode active material is 0.01.

[0179] It should be noted that in step 1.2 of Example 1, the first oxide is mixed with the positive electrode active material and then sintered, that is, the first oxide coating the positive electrode active material as described in the embodiments of this application (hereinafter referred to as "coating"); if the first oxide and the positive electrode active material are directly mixed without a sintering process, that is, the first oxide and the positive electrode active material are mixed as described in the embodiments of this application (hereinafter referred to as "mixing").

[0180] (1.3) Preparation of the positive electrode sheet: The positive active material mixed in step 1.2 is mixed with the first oxide, the binder polyvinylidene fluoride (PVDF), and the conductive agent (carbon black) at a weight ratio of 96:1.5:2.5 to obtain the positive electrode material. The positive electrode material is dissolved in the solvent N-methylpyrrolidone (NMP) and thoroughly stirred to prepare a positive electrode slurry. The positive electrode slurry is uniformly coated on two opposite surfaces of the positive current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet. The loading of the positive active material on one side of the positive electrode sheet is 0.016 g / cm³. 2 .

[0181] (2) Preparation of the negative electrode sheet: 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. After thorough mixing, a negative electrode slurry was prepared. The negative electrode slurry was coated onto a copper foil (negative electrode current collector), and then dried, cold-pressed, and slit to obtain the negative electrode sheet. The loading of the negative electrode active material on one side of the negative electrode sheet was 0.007 g / cm³. 2 .

[0182] (3) Separation membrane: A polypropylene film with a thickness of 12μm is used.

[0183] (4) Preparation of electrolyte: Methyl trifluoroethyl carbonate (FEMC) and fluoroethylene carbonate (FEC) are mixed at a volume ratio of 7:3. Then, LiPF6 is uniformly dissolved in the above solution to obtain an electrolyte with a concentration of 1 mol / L.

[0184] (5) Preparation of lithium-ion battery: The above positive electrode sheet, separator and negative electrode sheet are stacked and wound in sequence to obtain electrode assembly; the electrode assembly is placed in outer packaging, the electrolyte prepared above is added, and after encapsulation, standing, formation and aging processes, a secondary battery is obtained.

[0185] [Example 2]

[0186] The difference between Example 2 and Example 1 is that M is Zr.

[0187] [Example 3]

[0188] The difference between Example 3 and Example 1 is that M is Te.

[0189] [Example 4]

[0190] The difference between Example 4 and Example 1 is that M is Ta.

[0191] [Example 5]

[0192] The difference between Example 5 and Example 1 is that M is Si.

[0193] [Example 6]

[0194] The difference between Example 6 and Example 1 is that M is S.

[0195] [Example 7]

[0196] The difference between Example 7 and Example 1 is that M is Fe.

[0197] [Example 8]

[0198] The difference between Example 8 and Example 1 is that D is 0.0005.

[0199] [Example 9]

[0200] The difference between Example 9 and Example 1 is that D is 0.001.

[0201] [Example 10]

[0202] The difference between Example 10 and Example 1 is that D is 0.002.

[0203] [Example 11]

[0204] The difference between Example 11 and Example 1 is that D is 0.02.

[0205] [Example 12]

[0206] The difference between Example 12 and Example 1 is that D is 0.05.

[0207] [Example 13]

[0208] The difference between Example 13 and Example 1 is that D is 0.1.

[0209] [Example 14]

[0210] The difference between Example 14 and Example 1 is that the positive electrode active material is directly mixed with the first oxide without a sintering process.

[0211] [Example 15]

[0212] The difference between Example 15 and Example 1 is that the first oxide includes LiNbO3.

[0213] [Example 16]

[0214] The difference between Example 16 and Example 1 is that the first oxide includes HNbO3.

[0215] [Example 17]

[0216] The difference between Example 17 and Example 1 is that the positive electrode active material includes Li 1.01 Ni 0.5 Mn 1.49 Nb 0.01 O 3.99 .

[0217] [Example 18]

[0218] The difference between Example 18 and Example 1 is that the positive electrode active material includes Li. 1.01 Ni 0.5 Fe 0.1 Mn 1.4 O 3.99 .

[0219] [Comparative Example 1]

[0220] The difference between Comparative Example 1 and Example 1 is that the first oxide is not included.

[0221] Table 1. Experimental parameters of Examples 1-18 and Comparative Example 1

[0222] Example M First oxide Positive electrode active material D Method of adding the first oxide Example 1 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 2 Zr <![CDATA[Li2ZrO3]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 3 Te <![CDATA[Li2TeO3]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 4 Ta <![CDATA[Li3TaO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 5 Si <![CDATA[Li2SiO3]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 6 S <![CDATA[Li2SO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 7 Fe <![CDATA[Li5FeO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 8 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.0005 Cover Example 9 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.001 Cover Example 10 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.002 Cover Example 11 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.02 Cover Example 12 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.05 Cover Example 13 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.1 Cover Example 14 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 mix Example 15 Nb <![CDATA[LiNbO3]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 16 Nb <![CDATA[HNbO3]]> <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> 0.01 Cover Example 17 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 Ni 0.5 Mr 1.49 No 0.01 O 3.99 ]]> 0.01 Cover Example 18 Nb <![CDATA[Li3NbO4]]> <![CDATA[Li 1.01 In 0.4 Want 0.1 Mn 1.5 SHE 3.97 ]]> 0.01 Cover Comparative Example 1 / / <![CDATA[Li 1.01 In 0.5 Mn 1.5 SHE 3.98 ]]> / /

[0223] The following is a brief description of the testing methods for the physicochemical and performance parameters involved in the embodiments of this application. It should be understood that the following testing methods are only examples, and other testing methods known in the art can also be used for testing.

[0224] 1.MO y Group detection: can be performed by inductively coupled plasma optical emission spectrometry (ICP) and X-ray diffraction (XRD).

[0225] 2. pH measurement:

[0226] 2.1. pH measurement of the positive electrode film: When the secondary battery is discharged to ≤2V, remove the battery, take out the positive electrode plate and scrape off the film powder, mix it with water at a ratio of 1:10 and stir thoroughly, then take the supernatant and measure it with a pH meter.

[0227] 2.2 pH measurement of the first oxide: Mix it with water at a ratio of 1:10 and stir thoroughly. Then take the supernatant and measure it with a pH meter.

[0228] 3.Li 1+k Li 1+t Me a N b Mn 2-a-b O 4-k G k The content of each element in the sample can be measured by inductively coupled plasma spectrometry (ICP).

[0229] 4. Volume average particle size test: This can be determined by measuring the raw materials used to prepare the positive electrode sheet. As an example, the volume average particle size Dv50 can be measured using a laser particle size analyzer in accordance with GB / T 19077-2016 Particle size distribution laser diffraction method.

[0230] In addition, the positive electrode sheet can be observed using a scanning electron microscope. A specific area can be selected, and the volume average particle size can be calculated based on the size and number of particles observed in that area.

[0231] 5. Battery Cycle Performance Test: At 45℃, after standing for 5 minutes, the secondary battery was charged at a constant current of 1C to a voltage of 4.9V, then charged at a constant voltage of 4.9V to a current of 0.05C0. After standing for 5 minutes, the secondary battery was discharged at a constant current of 1C0 to a voltage of 3.0V. This constitutes one cycle. The above operation was repeated, and the discharge capacity value Cn of each cycle was extracted. The discharge capacity value of the first cycle was recorded as Cn. The number of cycles when Cn / C1 = 80% is the cycle life of the battery. Specific test results are shown in Table 2.

[0232] 6. Battery Storage Performance Test: At 25℃, the secondary battery was charged at a constant current of 0.33C1 to a voltage of 4.9V, and then charged at a constant voltage of 4.9V to a current of 0.05C1. The secondary battery was then placed at 45℃ for 100 days, removed, and allowed to stand at room temperature before being discharged at a constant current of 0.33C to a voltage of 3.0V. A capacity test was then performed at 25℃, and the discharge capacity value C100d was extracted. C100d / C1 represents the reversible capacity retention rate of the battery after 100 days of storage. Specific test results are shown in Table 2.

[0233] Table 2 Test results of Examples 1-18 and Comparative Example 1

[0234]

[0235]

[0236] In the above embodiments, the pH value of the positive electrode can be used to determine the effect of the first oxide on H. + The degree of tolerance. A higher pH value at the positive electrode indicates that the primary oxide has neutralized more H+. + H + The lower the pH value, the less corrosion occurs in the positive electrode film; conversely, the lower the pH value, the lower the acid resistance of the positive electrode sheet or film. + The higher the degree of corrosion on the positive electrode film, the better.

[0237] As can be seen from Examples 1-18 and Comparative Example 1, adding MO-containing materials to the positive electrode sheet...y The first oxide of the group can make the positive electrode film layer strongly alkaline, that is, the first oxide can neutralize the acidic H. + Lower H + The degree of corrosion on the positive electrode film layer is reduced, thereby improving the battery's storage and cycle performance.

[0238] As can be seen from Examples 1-4 and Examples 5-7, by including at least one of Te, Zr, Nb, and Ta in M, it is beneficial to further improve the performance of the battery.

[0239] As can be seen from Examples 1-4 and Examples 5-7, when the pH of the positive electrode is greater than 10.5, the battery performance can be further improved.

[0240] As can be seen from Examples 8-13, by maintaining the mass ratio D of M to the positive electrode active material between 0.001 and 0.1, the pH value of the positive electrode can be further increased, thereby further improving the cycle performance and storage performance of the battery.

[0241] As can be seen from Examples 1 and 14, the addition of the first oxide to the positive electrode film layer by direct mixing or sintering coating can improve battery performance; furthermore, when it is mixed with the positive electrode active material in the form of sintering coating, the battery performance can be further improved.

[0242] As can be seen from Examples 1, 15, and 16, in lithium-ion secondary batteries, the use of a first oxide containing Li can further improve the battery's storage performance and cycle performance.

[0243] As can be seen from Examples 1 and 17, MO is also doped into the positive electrode active material. y The M in the group can further improve the battery's storage performance and cycle performance.

[0244] As can be seen from Examples 1 and 18, by incorporating two transition metals into the positive electrode active material, the cycle performance and storage performance of the battery are significantly improved.

[0245] Figure 6 This is a SEM image of the positive electrode film layer according to one embodiment of this application. Specifically, it is a SEM image of the positive electrode film layer represented by Example 1. Figure 6 It can be seen that the first oxide is uniformly coated on the surface of the positive electrode active material particles.

[0246] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A secondary battery, characterized in that, include: A positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer, the positive electrode film layer being disposed on at least one side of the current collector, the positive electrode film layer comprising a first oxide; in, The first oxide includes MO y A group, y≥3, where M is an element with a valence greater than or equal to +4 and is at least one element in group IVA, VA, VIA, IVB, VB, or VIB.

2. The secondary battery according to claim 1, characterized in that, The M includes at least one of Te, Zr, Nb, Ta, Mo, and W.

3. The secondary battery according to claim 1 or 2, characterized in that, pH of the first oxide 1 Satisfy: pH 1 ≥10.

4. The secondary battery according to any one of claims 1-3, characterized in that, pH of the first oxide 1 Satisfying: 11 ≤ pH 1 ≤13.

5. The secondary battery according to any one of claims 1-4, characterized in that, When the secondary battery is discharged to less than or equal to 2V, the pH of the positive electrode film... 2 Satisfy: pH 2 ≥10.

6. The secondary battery according to any one of claims 1-5, characterized in that, When the secondary battery is discharged to less than or equal to 2V, the pH of the positive electrode film... 2 Satisfies: 10.5 ≤ pH 2 ≤12.

7. The secondary battery according to any one of claims 1-6, characterized in that, The positive electrode film layer also includes a positive electrode active material; The mass ratio D of M to the positive electrode active material satisfies: 0.001 ≤ D ≤ 0.

1.

8. The secondary battery according to any one of claims 1-7, characterized in that, The first oxide has a Dv50 that satisfies: Dv50≤10μm.

9. The secondary battery according to any one of claims 1-8, characterized in that, The Dv50 of the first oxide satisfies: Dv50≤1μm.

10. The secondary battery according to any one of claims 1-9, characterized in that, The first oxide has a Dv50 that satisfies: Dv50≤100nm.

11. The secondary battery according to any one of claims 7-10, characterized in that, The first oxide is distributed on the surface of the positive electrode active material.

12. The secondary battery according to any one of claims 1-11, characterized in that, The first oxide satisfies: AxMO y x≥2; Wherein, A includes alkali metal elements and at least one element from Group IIA.

13. The secondary battery according to any one of claims 1-12, characterized in that, The secondary battery is a lithium-ion secondary battery, and the first oxide includes Li. x MO y .

14. The secondary battery according to any one of claims 7-13, characterized in that, The chemical formula of the positive electrode active material includes M and Mn.

15. The secondary battery according to claim 14, characterized in that, The mass content of Mn in the positive electrode active material is greater than or equal to 20%.

16. The secondary battery according to any one of claims 7-15, characterized in that, The structure of the positive electrode active material includes a spinel structure.

17. The secondary battery according to any one of claims 7-16, characterized in that, The positive electrode active material includes Li 1+t Me a N b Mn 2-a-b O 4-k-g G g -0.1≤t≤2.2, 0.2≤a≤1.0, 0≤b≤0.3, 0.2≤a+b≤1, -0.1≤k≤0.3, 0≤g≤0.1; Me includes at least one of Cr, Fe, Co, Ni, and Cu; N includes at least one of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Zn, Ag, Cd, lanthanides, and M; G includes at least one of F, Cl, Br, and I.

18. The secondary battery according to claim 17, characterized in that, The Me includes Ni.

19. The secondary battery according to claim 17 or 18, characterized in that, The Me includes Me 1 and me 2 The Me 1 Including Ni, the Me 2 It includes at least one of Cr, Fe, Co, and Cu.

20. An electrical device, characterized in that, include: The secondary battery according to any one of claims 1-19.

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