Secondary battery and electric device

Abstract

Embodiments of the present application provide a secondary battery and an electric device. The secondary battery comprises a positive electrode sheet, a separator, and a negative electrode sheet; at least one of the positive electrode sheet, the separator, or the negative electrode sheet comprises an ion trapping agent; the reduction potential of the ion trapping agent relative to lithium metal is 0-2 V. The cycle performance of the secondary battery provided by the embodiments of the present application is improved.

Description

Secondary batteries and electrical devices Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a secondary battery and an electrical device. Background Art

[0002] In recent years, secondary batteries, due to their high energy density and recyclability, have been widely used in energy storage systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. With the rapid development and widespread application of secondary batteries, higher requirements have been placed on their electrochemical performance and other properties.

[0003] Therefore, how to provide a secondary battery with good performance is a technical problem that needs to be solved urgently.

[0004] Summary of the Invention

[0005] The present application is made in view of the above-mentioned technical problems, and its purpose is to provide a secondary battery and an electrical device, wherein the cycle performance of the secondary battery is improved.

[0006] In a first aspect, the present application provides a secondary battery comprising a positive electrode sheet, a separator and a negative electrode sheet, wherein at least one of the positive electrode sheet, the separator or the negative electrode sheet comprises an ion capture agent, and the reduction potential of the ion capture agent relative to lithium metal is 0 to 2V.

[0007] In the embodiment of the present application, at least one of the positive electrode sheet, separator or negative electrode sheet of the secondary battery includes an ion capture agent, and the reduction potential of the ion capture agent relative to lithium metal is 0 to 2V. The positive electrode material is an important component of the secondary battery and directly affects the performance of the secondary battery. The positive electrode material containing transition metals will inevitably undergo the phenomenon of transition metal ion dissolution in the electrochemical environment. On the one hand, the dissolved transition metal ions destroy the structural stability of the original positive electrode material and thus affect the life of the secondary battery. On the other hand, the dissolved transition metal ions will migrate and deposit on the surface of the negative electrode material, catalyzing the decomposition and regeneration of the electrolyte and the negative electrode interface film, continuously consuming reversible active metals, and ultimately leading to a decrease in the performance of the secondary battery. In the technical solution of the embodiment of the present application, the reduction potential of the ion capture agent in the secondary battery relative to lithium metal is 0 to 2V, and the reduction potential of the transition metal ions relative to lithium metal is generally above 2V. Therefore, the ion capture agent can reduce the transition metal ions dissolved in the secondary battery into low-valent ions that are not easily dissolved, or reduce them to metal elements, thereby improving the situation where the transition metal ions catalyze the decomposition of the electrolyte and the negative electrode interface film. In addition, due to H +The reduction potential of the ion scavenger relative to lithium metal is higher than that of the transition metal ion relative to lithium metal, so the ion scavenger can also convert the H + Reduction, that is, to remove acidic substances in the electrolyte (such as HF, organic acid RH + , H· free radicals, etc.), further improving the performance of the secondary battery. Therefore, the cycle performance of the secondary battery provided by the embodiment of the present application is improved.

[0008] In a possible implementation, the ion capture agent includes at least one of an active metal and an alkali metal compound. Optionally, the active metal includes at least one of Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, Al, Ti, or V; Optionally, the active metal includes at least one of Li, Na, Mg, Al, Ti, or V; Optionally, the alkali metal compound includes A 1 x B, A 2 y Ti5O 12 , and at least one of the compounds represented by formula (I), formula (II) or formula (III):

[0009] Among them, A 1 、A 2 、A 3 、A 4 、A 5 、A 6 Each independently includes at least one of Li, Na or K, B includes C, Si or Sn, x≥0.05, y>4, R, R1, R2, R3, and R4 independently include a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an alkenyl group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an alkenyl group having 6 to 7 carbon atoms, at least one of an aryl group having 1 to 26 carbon atoms, an aryl group having 6 to 26 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, a carboxyl group having 1 to 20 carbon atoms, a carboxyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, a carbonyl group having 1 to 20 carbon atoms, a carbonyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an aryloxy group having 6 to 26 carbon atoms, and an aryloxy group having 6 to 26 carbon atoms substituted by a sulfonic acid group or a sulfonyl group.

[0010] In a possible implementation, the A 1 x B includes Li 1 / 6 C, Na 1 / 6 C, K 1 / 8 C. Li 4.4 Si, or Li4.4 At least one of Sn.

[0011] In a possible implementation, 5≤y≤7, the A 2 y Ti5O 12 Including Li7Ti5O 12 or Na7Ti5O 12 At least one of .

[0012] In one possible implementation, the compound represented by formula (I) includes at least one of n-butyllithium, naphthyllithium or biphenyllithium.

[0013] In one possible implementation, the compound represented by formula (II) comprises At least one of .

[0014] In one possible implementation, the compound represented by formula (III) comprises At least one of .

[0015] In a possible implementation, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector, and the positive electrode film layer includes the ion capture agent.

[0016] In a possible implementation, the mass proportion of the ion capture agent in the positive electrode film layer is 0.1% to 10%. Optionally, the mass proportion of the ion capture agent in the positive electrode film layer is 1% to 5%.

[0017] The mass proportion of the ion capture agent in the positive electrode film layer is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0018] In a possible implementation, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector, and the negative electrode film layer includes the ion capture agent.

[0019] In a possible implementation, the mass proportion of the ion capture agent in the negative electrode film layer is 0.1% to 10%. Optionally, the mass proportion of the ion capture agent in the negative electrode film layer is 1% to 5%.

[0020] The mass proportion of the ion capture agent in the negative electrode film layer is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0021] In a possible implementation, the isolation membrane includes a porous base membrane, and the porous base membrane includes the ion capture agent.

[0022] In a possible implementation, the mass proportion of the ion capture agent in the porous base membrane is 1% to 20%. Optionally, the mass proportion of the ion capture agent in the porous base membrane is 5% to 10%.

[0023] The mass proportion of the ion capture agent in the porous base membrane is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0024] In a possible implementation, the isolation membrane includes a porous base membrane and a porous coating layer disposed on the porous base membrane, and the porous coating layer includes the ion capture agent.

[0025] In a possible implementation, the mass proportion of the ion capture agent in the porous coating layer is 8% to 50%. Optionally, the mass proportion of the ion capture agent in the porous coating layer is 10% to 20%.

[0026] The mass proportion of the ion capture agent in the porous coating is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0027] In a second aspect, the present application provides an electrical device, comprising the secondary battery in the first aspect and any possible implementation thereof.

[0028] The embodiment of the present application provides a secondary battery, in which at least one of the positive electrode sheet, separator or negative electrode sheet of the secondary battery includes an ion capture agent, and the reduction potential of the ion capture agent relative to lithium metal is 0 to 2V. The positive electrode material is an important component of the secondary battery and directly affects the performance of the secondary battery. The positive electrode material containing transition metals will inevitably undergo the phenomenon of transition metal ion dissolution in the electrochemical environment. On the one hand, the dissolved transition metal ions destroy the structural stability of the original positive electrode material, thereby affecting the life of the secondary battery. On the other hand, the dissolved transition metal ions will migrate and deposit on the surface of the negative electrode material, catalyzing the decomposition and regeneration of the electrolyte and the negative electrode interface film, continuously consuming reversible active metals, and ultimately leading to a decrease in the performance of the secondary battery. In the technical solution of the embodiment of the present application, the reduction potential of the ion capture agent in the secondary battery relative to lithium metal is 0 to 2V, and the reduction potential of the transition metal ions relative to lithium metal is generally above 2V. Therefore, the ion capture agent can reduce the transition metal ions dissolved in the secondary battery into low-valent ions that are not easily dissolved, or reduce them to metal elements, thereby improving the situation where the transition metal ions catalyze the decomposition of the electrolyte and the negative electrode interface film. In addition, due to H +The reduction potential of the ion scavenger relative to lithium metal is higher than that of the transition metal ion relative to lithium metal, so the ion scavenger can also convert the H + Reduction, that is, to remove acidic substances in the electrolyte (such as HF, organic acid RH + , H· free radicals, etc.), further improving the performance of the secondary battery. Therefore, the cycle performance of the secondary battery provided by the embodiment of the present application is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0030] FIG1 is a schematic diagram of a positive electrode sheet disclosed in one embodiment of the present application;

[0031] FIG2 is a schematic diagram of a negative electrode sheet disclosed in one embodiment of the present application;

[0032] FIG3 is a schematic diagram of an isolation membrane disclosed in an embodiment of the present application;

[0033] FIG4 is a schematic diagram of a battery cell disclosed in an embodiment of the present application;

[0034] FIG5 is a schematic diagram of the exploded structure of a battery cell disclosed in one embodiment of the present application;

[0035] FIG6 is a schematic diagram of the exploded structure of a secondary battery disclosed in one embodiment of the present application;

[0036] FIG7 is a schematic diagram of an electrical device disclosed in an embodiment of the present application.

[0037] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0038] Below, the embodiments of the battery cells, batteries, and electrical devices of the present application are described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0039] In the description of this application, it should be noted that, unless otherwise specified, "plurality" means more than two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are merely for the purpose of facilitating the description of this application and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting this application. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] " scope " disclosed in the application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and selected lower limit and upper limit define the boundary of special scope. The scope that this mode limits can be to include end value or not include end value, and can be combined arbitrarily, and promptly any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 are listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0042] If not otherwise specified, the “include” and “comprising” mentioned in this application represent open-endedness. For example, the “include” and “comprising” may mean including or comprising other components not listed.

[0043] Unless otherwise specified, the term "and / or" is inclusive in this application. For example, the phrase "A and / or B" means "A, B, or both A and B." More specifically, the condition "A and / or B" is satisfied if any of the following conditions are met: 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).

[0044] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0045] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0046] Unless otherwise specified, the following terms have the following meanings. Any undefined terms have their generally accepted meanings in the art.

[0047] "Alkyl" refers to a monovalent saturated hydrocarbon group having one or more carbon atoms, optionally 1 to 20. For example, alkyl includes straight-chain and branched hydrocarbon groups, such as methyl (CH3-), ethyl (CH3CH2-), n-propyl (CH3CH2CH2-), isopropyl ((CH3)2CH-), n-butyl (CH3CH2CH2CH2-), isobutyl ((CH3)2CHCH2-), sec-butyl ((CH3)(CH3CH2)CH-), tert-butyl ((CH3)3C-), n-pentyl (CH3CH2CH2CH2CH2-), neopentyl ((CH3)3CCH2-), and the like.

[0048] "Alkenyl" refers to a straight or branched hydrocarbon group having one or more carbon atoms and at least one double bond unsaturated site, optionally with 2 to 20 carbon atoms, such as ethenyl (CH2=CH-), propenyl (CH3CH=CH-), allyl (CH2=CH-CH2-), n-butenyl (-CH3CH2CH=CH-), etc.

[0049] "Aryl" refers to an aromatic compound having a single ring or multiple condensed rings, optionally with 6 to 26 carbon atoms. Examples of aryl groups include phenyl, naphthyl, and indenyl. Aryl groups also include single rings fused to an aryl group, such as tetrahydronaphthyl and indanyl.

[0050] "Carboxyl" refers to a group having one or more carbon atoms and a -CO2H functional group, optionally with 1 to 20 carbon atoms.

[0051] "Carbonyl" refers to a group having one or more carbon atoms and a -CO- functional group, and optionally, the number of carbon atoms is 1 to 20.

[0052] "Aryloxy" refers to a group formed by connecting at least one carbon atom on the aromatic ring of an aryl group to an oxygen atom, and optionally, the number of carbon atoms is 6 to 26.

[0053] "Sulfonic acid" refers to -SO3H.

[0054] "Sulfonyl" refers to RS(=O)2-, where R includes hydrogen, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclic, and the like.

[0055] Due to their high energy density and recyclability, secondary batteries are widely used in energy storage systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. With the rapid development and widespread application of secondary batteries, higher requirements have been placed on their energy density, cycle performance, discharge capacity, and other performance characteristics.

[0056] Positive electrode materials are one of the key materials that determine the performance of secondary batteries. They mainly include metal oxides and polyanion salts. Among them, layered metal oxides and spinel metal oxides containing transition metals are widely used as positive electrode materials. The above-mentioned positive electrode materials containing transition metals have advantages such as high energy density and good cycle performance, which are beneficial to improving the performance of battery cells. However, positive electrode materials containing transition metals will inevitably experience the phenomenon of transition metal ion dissolution in the electrochemical environment. On the one hand, the dissolved transition metal ions destroy the structural stability of the original positive electrode material, thereby affecting the battery life. On the other hand, the dissolved transition metal ions will migrate and deposit on the surface of the negative electrode material, catalyzing the decomposition and regeneration of the electrolyte and the negative electrode interface film, continuously consuming reversible active metals, and ultimately leading to a decline in the performance of the battery cell, thereby affecting the performance of the secondary battery.

[0057] In view of this, an embodiment of the present application provides a secondary battery, wherein at least one of the positive electrode sheet, separator or negative electrode sheet of the secondary battery includes an ion capture agent, and the reduction potential of the ion capture agent relative to lithium metal is 0 to 2V, while the reduction potential of transition metal ions relative to lithium metal is generally above 2V. Therefore, the ion capture agent can reduce the transition metal ions dissolved in the battery cell into low-valent ions that are difficult to dissolve, or reduce them to metal elements, thereby improving the situation where the transition metal ions catalyze the decomposition of the electrolyte and the negative electrode interface film. In addition, due to H + The reduction potential of the ion scavenger relative to lithium metal is higher than that of the transition metal ion relative to lithium metal, so the ion scavenger can also convert the H + Reduction, that is, to remove acidic substances in the electrolyte (such as HF, organic acid RH +, H· free radicals, etc.), further improving the performance of the secondary battery. Therefore, the cycle performance of the secondary battery provided by the embodiment of the present application is improved.

[0058] The following describes in detail several embodiments of the present application.

[0059] An embodiment of the present application provides a secondary battery, including a positive electrode sheet, a separator and a negative electrode sheet, at least one of the positive electrode sheet, the separator or the negative electrode sheet includes an ion capture agent, and the reduction potential of the ion capture agent relative to lithium metal is 0 to 2V.

[0060] Ion scavengers, as used herein, are substances capable of consuming free transition metal ions in secondary batteries. The reduction potential of ion scavengers relative to lithium metal is 0-2V, while the reduction potential of transition metal ions relative to lithium metal is generally above 2V. Therefore, ion scavengers have a stronger reducing ability than transition metal ions. Ion scavengers can reduce free transition metal ions to low-valent ions that are difficult to dissolve from the positive electrode material, or to elemental metal.

[0061] Positive electrode materials are an important component of secondary batteries and directly affect the performance of secondary batteries. Positive electrode materials containing transition metals will inevitably experience the dissolution of transition metal ions in the electrochemical environment. On the one hand, the dissolved transition metal ions destroy the structural stability of the original positive electrode material and thus affect the life of the battery cell. On the other hand, the dissolved transition metal ions will migrate and deposit on the surface of the negative electrode material, catalyzing the decomposition and regeneration of the electrolyte and the negative electrode interface film, continuously consuming reversible active metals, and ultimately leading to a decline in the performance of the secondary battery.

[0062] For example, the positive electrode material may include a phosphate material with an olivine structure, a material with a spinel structure, or a transition metal oxide with a layered structure. Specifically, for example, lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiMnFePO4), lithium manganese oxide (LiMn2O4), and ternary materials. The iron ions, nickel ions, and manganese ions in the above-mentioned positive electrode materials are all susceptible to dissolution from the positive electrode materials.

[0063] At least one of the positive electrode sheet, separator, or negative electrode sheet of the secondary battery provided in the embodiment of the present application includes an ion capture agent, and the reduction potential of the ion capture agent relative to lithium metal is 0 to 2V, while the reduction potential of transition metal ions relative to lithium metal is generally above 2V. Therefore, the ion capture agent can reduce the transition metal ions dissolved in the secondary battery into low-valent ions that are difficult to dissolve, or reduce them to metal elements, thereby improving the situation where the transition metal ions catalyze the decomposition of the electrolyte and the negative electrode interface film. In addition, due to H +The reduction potential of ions relative to lithium metal is higher than that of transition metal ions relative to lithium metal, so ion scavengers can also convert H + Reduction, that is, to remove acidic substances in the electrolyte (such as HF, organic acid RH + , H· free radicals, etc.), further improving the performance of the secondary battery. Therefore, the cycle performance of the secondary battery provided by the embodiment of the present application is improved.

[0064] It should be understood that in the embodiments of the present application, different types of ion capture agents can be selected according to the different types of free transition metal ions dissolved in the battery cells.

[0065] Alternatively, in some embodiments, the ion capture agent includes at least one of a compound of an active metal and an alkali metal.

[0066] Specifically, the active metal may include at least one of Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, Al, Ti or V. Optionally, the active metal includes at least one of Li, Na, Mg, Al, Ti or V.

[0067] Optionally, the alkali metal compound includes A 1 x B, A 2 y Ti5O 12 , and at least one of the compounds represented by formula (I), formula (II) or formula (III):

[0068] Among them, A 1 、A 2 、A 3 、A 4 、A 5 、A 6 Each independently includes at least one of Li, Na or K, B includes C, Si or Sn, x≥0.05, y>4, R, R1, R2, R3, and R4 independently include a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an alkenyl group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an alkenyl group having 6 to 7 carbon atoms, at least one of an aryl group having 1 to 26 carbon atoms, an aryl group having 6 to 26 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, a carboxyl group having 1 to 20 carbon atoms, a carboxyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, a carbonyl group having 1 to 20 carbon atoms, a carbonyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an aryloxy group having 6 to 26 carbon atoms, and an aryloxy group having 6 to 26 carbon atoms substituted by a sulfonic acid group or a sulfonyl group.

[0069] In the embodiments of the present application, the dotted line in formula (II) indicates that R1 and R2 may be connected to form a ring or may not be connected; the dotted line in formula (III) indicates that R3 and R4 may be connected to form a ring or may not be connected.

[0070] Optionally, A 1 x B includes LiC6, NaC6, KC8, Li 4.4 Si, Li 4.4 Sn or Li 22 At least one of Si5.

[0071] In the embodiment of the present application, A 1 x The value of x in B is related to the specific substance selected for B. For example, when B is carbon (C), the upper limit of the value of x is 1 / 6; for another example, when B is silicon (Si) or tin (Sn), the upper limit of the value of x is 4.4.

[0072] Optionally, 5≤y≤7, A 2 y Ti5O 12 Including Li7Ti5O 12 or Na7Ti5O 12 At least one of .

[0073] Optionally, the compound represented by formula (I) includes at least one of n-butyllithium, naphthyllithium or biphenyllithium.

[0074] Optionally, the compound represented by formula (II) comprises At least one of .

[0075] Optionally, the compound represented by formula (III) comprises At least one of .

[0076] Optionally, in some embodiments, as shown in FIG1 , the positive electrode plate 1 includes a positive electrode current collector 11 and a positive electrode film layer 12 disposed on the positive electrode current collector, and the positive electrode film layer 12 includes an ion capture agent.

[0077] The positive electrode current collector 11 has two surfaces arranged along its thickness direction. Optionally, as shown in FIG1 , both surfaces of the positive electrode current collector 11 are provided with a positive electrode film layer 12 , and the positive electrode current collector 11 and the positive electrode film layer 12 are arranged in sequence along the thickness direction of the positive electrode sheet 1 (e.g., the z direction in FIG1 ).

[0078] Optionally, in some other embodiments, a positive electrode film layer 12 is provided on one of two surfaces of the positive electrode current collector 11 that are opposite to each other in the thickness direction.

[0079] Optionally, in some embodiments, the mass proportion of the ion capture agent in the positive electrode film layer 12 is 0.1% to 10%. Optionally, the mass proportion of the ion capture agent in the positive electrode film layer 12 is 1% to 5%.

[0080] Specifically, the mass proportion of the ion capture agent in the positive electrode film layer 12 can be 0.1%, 1%, 3%, 5%, 7%, 10%, or a value between any two of the above values.

[0081] The mass proportion of the ion capture agent in the positive electrode film layer is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0082] Optionally, in some embodiments, as shown in FIG2 , the negative electrode plate 2 includes a negative electrode current collector 21 and a negative electrode film layer 22 disposed on the negative electrode current collector, and the negative electrode film layer 22 includes an ion capture agent.

[0083] The negative electrode current collector 21 has two surfaces arranged along its thickness direction. Optionally, as shown in FIG2 , both surfaces of the negative electrode current collector 21 are provided with a negative electrode film layer 22 , and the negative electrode current collector 21 and the negative electrode film layer 22 are arranged in sequence along the thickness direction of the negative electrode sheet 2 (e.g., the z direction in FIG2 ).

[0084] Optionally, in some other embodiments, a negative electrode film layer 22 is provided on one of two surfaces of the negative electrode current collector 21 that are opposite to each other in the thickness direction.

[0085] Optionally, in some embodiments, the mass proportion of the ion capture agent in the negative electrode film layer 22 is 0.1% to 10%. Optionally, the mass proportion of the ion capture agent in the negative electrode film layer 22 is 1% to 5%.

[0086] Specifically, the mass proportion of the ion capture agent in the negative electrode film layer 22 can be 0.1%, 1%, 3%, 5%, 7%, 10%, or a value between any two of the above values.

[0087] The mass proportion of the ion capture agent in the negative electrode film layer is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0088] Alternatively, in some embodiments, the separator includes a porous base membrane, and the porous base membrane includes an ion capture agent.

[0089] Optionally, in some embodiments, the mass proportion of the ion capture agent in the porous base membrane is 1% to 20%. Optionally, the mass proportion of the ion capture agent in the porous base membrane is 5% to 10%.

[0090] Specifically, the mass proportion of the ion capture agent in the porous base membrane can be 1%, 5%, 10%, 15%, 20%, or a value between any two of the above values.

[0091] The mass proportion of the ion capture agent in the porous base membrane is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0092] Alternatively, in some embodiments, as shown in FIG3 , the separator 3 includes a porous base membrane 31 and a porous coating layer 32 disposed on the porous base membrane 31 , and the porous coating layer 32 includes an ion capture agent.

[0093] Optionally, the porous base membrane 31 has two surfaces arranged along its thickness direction. Optionally, as shown in FIG3 , both surfaces of the porous base membrane 31 are provided with a porous coating layer 32 , and the porous base membrane 31 and the porous coating layer 32 are arranged in sequence along the thickness direction of the separator 3 (e.g., the z direction in FIG3 ).

[0094] Optionally, in some other embodiments, one of two surfaces of the porous base membrane 31 that are opposite to each other in the thickness direction is provided with a porous coating layer 32 .

[0095] Optionally, in some embodiments, the mass proportion of the ion capture agent in the porous coating layer 32 is 8% to 50%. Optionally, the mass proportion of the ion capture agent in the porous coating layer 32 is 10% to 20%.

[0096] Specifically, the mass proportion of the ion capture agent in the porous coating layer 32 may be 8%, 10%, 15%, 20%, 30%, 40%, 50%, or a value between any two of the above values.

[0097] The mass proportion of the ion capture agent in the porous coating is within the given range, and the ion capture agent can play a good role in reducing transition metal ions, thereby further improving the cycle performance of the battery.

[0098] The following is a detailed introduction to the positive electrode sheet, negative electrode sheet, electrolyte and separator in the secondary battery.

[0099] [Positive electrode]

[0100] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0101] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0102] Optionally, in some embodiments, the positive electrode plate may include the above-mentioned ion capture agent. For example, the ion capture agent may be contained in the positive electrode film layer of the positive electrode plate.

[0103] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0104] In some embodiments, the positive electrode active material may be a positive electrode active material for lithium ion batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates containing olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for lithium ion batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0105] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0106] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the ion capture agent of the present application, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0108] [Negative electrode]

[0109] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0110] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0111] Optionally, in some embodiments, the negative electrode plate may include the above-mentioned ion capture agent. For example, the ion capture agent may be contained in the negative electrode film layer of the negative electrode plate.

[0112] 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 base layer and a metal layer formed on at least one surface of the polymer base material. 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 base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0113] In some embodiments, the negative electrode active material may adopt negative electrode active materials for batteries that are well known in the art. 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, lithium titanate, etc. The silicon-based material may include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional 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.

[0114] In some embodiments, the negative electrode film layer may further include a binder. The binder may include 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).

[0115] In some embodiments, the negative electrode film layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0116] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0117] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the ion capture agent of the present application, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0118] [Electrolyte]

[0119] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. This application has no specific restrictions on the type of electrolyte, and it can be selected according to needs.

[0120] In some embodiments, the electrolyte may include 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 difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0121] In some embodiments, the solvent of the electrolyte may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0122] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0123] [Isolation film]

[0124] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0125] Alternatively, in some embodiments, the separator may include the above-mentioned ion capture agent. For example, the ion capture agent may be contained in the porous base film of the separator. For another example, the separator includes a porous base film and a porous coating layer, and the ion capture agent may be contained in the porous coating layer.

[0126] In some embodiments, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0127] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0128] In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0129] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0130] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape. For example, FIG4 shows a battery cell 40 having a square structure as an example.

[0131] In some embodiments, referring to Figure 5, the outer packaging may include a shell 41 and a cover plate 43. The shell 41 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 41 has an opening connected to the receiving cavity, and the cover plate 43 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 42 through a winding process or a lamination process. The electrode assembly 42 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 42. The number of electrode assemblies 42 contained in the battery cell 40 can be one or more, and those skilled in the art can select according to specific actual needs.

[0132] In some embodiments, the secondary battery 50 may include multiple battery cells 40. For example, FIG6 is a schematic diagram of the structure of a secondary battery 50 according to one embodiment of the present application. The secondary battery 50 may include multiple battery cells 40. The secondary battery 50 may also include a housing 51. The housing 51 has a hollow interior and houses the multiple battery cells 40. For example, the multiple battery cells 40 may be connected in parallel, in series, or in a mixed combination and then placed in the housing 51.

[0133] Optionally, the secondary battery 50 may also include other structures, which will not be described in detail here. For example, the battery 10 may also include a busbar component, which is used to achieve electrical connection between multiple battery cells 40, such as parallel connection, series connection, or mixed connection. Specifically, the busbar component can achieve electrical connection between the battery cells 40 by connecting the electrode terminals of the battery cells 40. Furthermore, the busbar component can be fixed to the electrode terminals of the battery cells 40 by welding. The electrical energy of the multiple battery cells 40 can be further led out through the box 51 through a conductive mechanism. Optionally, the conductive mechanism may also belong to the busbar component.

[0134] The number of battery cells 40 can be set to any value based on different power requirements. Multiple battery cells 40 can be connected in series, parallel, or in a hybrid manner to achieve a larger capacity or power. Since each secondary battery 50 may include a large number of battery cells 40, for ease of installation, the battery cells 40 can be grouped, with each group of battery cells 40 forming a battery module. The number of battery cells 40 included in a battery module is not limited and can be set according to requirements. The battery can include multiple battery modules, which can be connected in series, parallel, or in a hybrid manner.

[0135] In addition, the present application also provides an electric device, which includes at least one of the battery cells, battery modules or batteries provided in the present application. The battery cells, battery modules or batteries can be used as the power source of the electric device, and can also be used as the energy storage unit of the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0136] As the electrical device, a battery cell, a battery module or a battery can be selected according to its usage requirements.

[0137] Figure 7 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery cell, a battery or battery module can be used.

[0138] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0139] [Example]

[0140] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0141] [Preparation of Secondary Battery]

[0142] [Example 1]

[0143] Preparation of positive electrode sheet: The positive electrode active material lithium manganate (LiMn2O4), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are dissolved in the solvent N-methylpyrrolidone (NMP) in a mass ratio of 90%:5%:5%, and after being fully stirred and mixed, they are coated on Al foil, dried, and cold pressed to obtain the positive electrode sheet.

[0144] Preparation of negative electrode sheet: Dissolve the negative electrode active material artificial graphite, conductive agent acetylene black, and binder PVDF in solvent NMP at a mass ratio of 90%:5%:5%, stir and mix thoroughly, then coat on Cu foil, dry, and cold press to obtain the negative electrode sheet.

[0145] Preparation of isolation membrane: Alumina (Al2O3), ion capture agent Li7Ti5O 12 PVDF, a binder, is dissolved in NMP solvent at a mass ratio of 80%:15%:5%, stirred and mixed thoroughly, then coated on a polyethylene (PE) base film and dried to obtain a separator.

[0146] Preparation of the electrolyte: Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30:70, and 1 M lithium hexafluorophosphate (LiPF6) electrolyte salt was dissolved therein to obtain an electrolyte.

[0147] Assembly of a lithium-ion battery: The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrode sheets to serve as an isolation layer, and then wound to obtain an electrode assembly; the electrode assembly is placed in a battery case, dried, and then injected with the above-mentioned electrolyte, and then subjected to processes such as formation and standing to obtain a lithium-ion battery 1, which is Example 1.

[0148] [Examples 2-5]

[0149] The difference between Example 2-5 and Example 1 is that the types of active materials of the positive electrode sheets in Examples 2-5 are lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel cobalt manganese oxide (LiNi 0.8 Co 0.1 Mn 0.1 O2), lithium iron phosphate (LiFePO4).

[0150] [Examples 6-15]

[0151] The difference between Example 6-15 and Example 1 is that the types of ion capture agents in the isolation membranes in Examples 6-15 are respectively Na7Ti5O 12 , Li powder, Al powder, Li 1 / 6 C. Li 4.4 Si, n-butyllithium, naphthyllithium,

[0152] [Examples 16-21]

[0153] The difference between Example 16-21 and Example 1 is that during the preparation of the isolation membrane in Example 16-21, Al2O3 and ion capture agent Li7Ti5O 12 The mass ratios of the adhesive PVDF are 80%:8%:12%, 80%:10%:10%, 75%:20%:5%, 40%:50%:10%, 85%:5%:10% and 35%:55%:10% respectively.

[0154] [Comparative Example 1]

[0155] The difference between Comparative Example 1 and Example 1 is that no ion capture agent is added to the isolation membrane in Comparative Example 1.

[0156] [Comparative Example 2]

[0157] The difference between Comparative Example 2 and Example 2 is that no ion capture agent is added to the isolation membrane in Comparative Example 2.

[0158] [Comparative Example 3]

[0159] The difference between Comparative Example 3 and Example 3 is that no ion capture agent is added to the isolation membrane in Comparative Example 3.

[0160] [Comparative Example 4]

[0161] The difference between Comparative Example 4 and Example 4 is that no ion capture agent is added to the isolation membrane in Comparative Example 4.

[0162] [Comparative Example 5]

[0163] The difference between Comparative Example 5 and Example 5 is that no ion capture agent is added to the isolation membrane in Comparative Example 5.

[0164] [Battery performance test]

[0165] 1. Battery capacity retention test

[0166] At 45°C, charge a lithium-ion secondary battery at a constant current of 1C to the upper voltage limit, then charge it at a constant voltage at the upper voltage limit until the current is less than 0.05C. Then discharge it at a constant current of 1C to the lower voltage limit. This charge and discharge cycle is considered one cycle. Repeat this cycle, and calculate the capacity retention of the lithium-ion secondary battery after 500 cycles.

[0167] The capacity retention rate (%) of the lithium ion secondary battery after 500 cycles at 45° C. = (discharge capacity at the 500th cycle / discharge capacity at the first cycle)×100%.

[0168] 2. Negative electrode transition metal content test after 500 cycles at 45°C

[0169] The lithium-ion secondary battery after 500 cycles at 45°C was disassembled, the negative electrode was removed, and the total content of transition metals (such as Ni, Co, Mn or Fe) on the negative electrode was tested using inductively coupled plasma atomic emission spectrometry in accordance with EPA 6010D-2014.

[0170] The voltage range selection for the above battery performance test sets different voltage parameters according to different battery systems. Among them, the upper and lower limits of the voltage of the lithium manganese oxide system are 3 to 4.3V; the upper and lower limits of the voltage of the lithium cobalt oxide system are 2.6 to 4.2V; the upper and lower limits of the voltage of the lithium nickel oxide system are 2.5 to 4.2V; the upper and lower limits of the voltage of the nickel cobalt manganese oxide system are 2.8 to 4.25V; and the upper and lower limits of the voltage of the lithium iron phosphate system are 2 to 3.65V.

[0171] The product parameters of different embodiments and comparative examples, as well as the test results of battery performance tests conducted on comparative examples 1-5 and embodiments 1-21 prepared according to the above method, are shown in Tables 1-5.

[0172] Table 1: Product parameters and performance test results of Comparative Example 1 and Examples 1, 6-21

[0173] From the comparison of the results of Comparative Example 1 and Examples 1 and 6-21, it can be seen that the ion capture agent Li7Ti5O provided in the examples of the present application 12、 Na7Ti5O 12、 Metal Li (powder), Metal Al (powder), Li 1 / 6 C. Li 4.4 Si, n-butyllithium, naphthyllithium, When added to lithium manganese oxide batteries respectively, the cycle performance of lithium manganese oxide batteries is significantly improved, and the transition metal content on the negative electrode plate is also significantly reduced.

[0174] From the comparison of the results of Examples 1 and 16-21, it can be seen that within a certain range, the greater the mass proportion of the ion capture agent in the porous coating, the greater the improvement in the cycle performance of the lithium manganese oxide battery. Beyond a certain range, as the mass proportion of the ion capture agent in the porous coating increases, the cycle performance of the lithium manganese oxide battery no longer improves significantly. In the embodiments of the present application, under the same other conditions, the mass proportion of the ion capture agent in the porous coating is in the range of 8% to 50%, and the cycle performance of the lithium manganese oxide battery is better.

[0175] Table 2: Product parameters and performance test results of Comparative Example 2 and Example 2

[0176] From the comparison between the results of Comparative Example 2 and Example 2, it can be seen that the ion capture agent Li7Ti5O 12 The cycle performance of the lithium cobalt oxide battery has been improved, and the transition metal content on the negative electrode has been significantly reduced.

[0177] Table 3: Product parameters and performance test results of Comparative Example 3 and Example 3

[0178] From the comparison between the results of Comparative Example 3 and Example 3, it can be seen that the ion capture agent Li7Ti5O 12 The cycle performance of the lithium nickel oxide battery has been improved, and the transition metal content on the negative electrode has been significantly reduced.

[0179] Table 4: Product parameters and performance test results of Comparative Example 4 and Example 4

[0180] From the comparison between the results of Comparative Example 4 and Example 4, it can be seen that the ion capture agent Li7Ti5O 12 The cycle performance of the nickel cobalt manganese oxide battery has been improved, and the transition metal content on the negative electrode has been significantly reduced.

[0181] Table 5: Product parameters and performance test results of Comparative Example 5 and Example 5

[0182] From the comparison between the results of Comparative Example 5 and Example 5, it can be seen that the ion capture agent Li7Ti5O 12 The cycle performance of the lithium iron phosphate battery has been improved, and the transition metal content on the negative electrode has been significantly reduced.

[0183] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A secondary battery comprising a positive electrode sheet, a separator and a negative electrode sheet, wherein at least one of the positive electrode sheet, the separator or the negative electrode sheet comprises an ion capture agent, and the reduction potential of the ion capture agent relative to lithium metal is 0 to 2V.

2. The isolation film according to claim 1, wherein: The ion capture agent includes at least one of active metal and alkali metal compounds; Optionally, the active metal includes at least one of Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, Al, Ti or V. Optionally, the active metal includes at least one of Li, Na, Mg, Al, Ti or V. Optionally, the alkali metal compound comprises A 1 x B. A 2 y Ti5O 12 , at least one of the compounds represented by formula (I), formula (II) or formula (III): Among them, A 1 , A 2 , A 3 , A 4 , A 5 , A 6 Each independently includes at least one of Li, Na, or K, B includes C, Si, or Sn, x≥0.05, y>4, R, R1, R2, R3, and R4 each independently include a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an alkenyl group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an alkenyl group having 6 to 8 carbon atoms, The present invention further comprises at least one of an aryl group having 6 to 26 carbon atoms, an aryl group having 6 to 26 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, a carboxyl group having 1 to 20 carbon atoms, a carboxyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, a carbonyl group having 1 to 20 carbon atoms, a carbonyl group having 1 to 20 carbon atoms substituted by a sulfonic acid group or a sulfonyl group, an aryloxy group having 6 to 26 carbon atoms, and an aryloxy group having 6 to 26 carbon atoms substituted by a sulfonic acid group or a sulfonyl group.

3. The secondary battery according to claim 2, wherein: The A 1 x B includes Li 1 / 6 C. Na 1 / 6 C.K 1 / 8 C. Li 4.4 Si or Li 4.4 At least one of Sn.

4. The secondary battery according to claim 2 or 3, wherein: 5≤y≤7; Optionally, the A 2 y Ti5O 12 Including Li7Ti5O 12 or Na7Ti5O 12 At least one of .

5. The secondary battery according to any one of claims 2 to 4, wherein The compound represented by formula (I) includes at least one of n-butyllithium, naphthyllithium or biphenyllithium.

6. The secondary battery according to any one of claims 2 to 5, wherein: The compounds represented by formula (II) include At least one of .

7. The secondary battery according to any one of claims 2 to 6, wherein The compounds represented by formula (III) include At least one of .

8. The secondary battery according to any one of claims 1 to 7, wherein The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector, and the positive electrode film layer includes the ion capture agent.

9. The secondary battery according to claim 8, wherein The mass proportion of the ion capture agent in the positive electrode film layer is 0.1% to 10%. Optionally, the mass proportion of the ion capture agent in the positive electrode film layer is 1% to 5%.

10. The secondary battery according to any one of claims 1 to 9, wherein The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on the negative electrode current collector, and the negative electrode film layer comprises the ion capture agent.

11. The secondary battery according to claim 10, wherein The mass proportion of the ion capture agent in the negative electrode film layer is 0.1% to 10%. Optionally, the mass proportion of the ion capture agent in the negative electrode film layer is 1% to 5%.

12. The secondary battery according to any one of claims 1 to 11, wherein The isolation membrane includes a porous base membrane, and the porous base membrane includes the ion capture agent.

13. The secondary battery according to claim 12, wherein: The mass proportion of the ion capture agent in the porous base membrane is 1% to 20%. Optionally, the mass proportion of the ion capture agent in the porous base membrane is 5% to 10%.

14. The secondary battery according to any one of claims 1 to 13, wherein The isolation membrane includes a porous base membrane and a porous coating layer disposed on the porous base membrane, wherein the porous coating layer includes the ion capture agent.

15. The secondary battery according to claim 14, wherein The mass proportion of the ion capture agent in the porous coating layer is 8% to 50%. Optionally, the mass proportion of the ion capture agent in the porous coating layer is 10% to 20%.

16. An electric device comprising the secondary battery according to any one of claims 1 to 15.

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