CN116759711A - Secondary battery cell, secondary battery, and electricity using device - Google Patents

Secondary battery cell, secondary battery, and electricity using device Download PDF

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Publication number
CN116759711A
CN116759711A CN202310601669.5A CN202310601669A CN116759711A CN 116759711 A CN116759711 A CN 116759711A CN 202310601669 A CN202310601669 A CN 202310601669A CN 116759711 A CN116759711 A CN 116759711A
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China
Prior art keywords
secondary battery
electrolyte
battery cell
positive electrode
ltoreq
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CN202310601669.5A
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Chinese (zh)
Inventor
吴则利
吴巧
韩昌隆
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to CN202310601669.5A priority Critical patent/CN116759711A/en
Publication of CN116759711A publication Critical patent/CN116759711A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
    • H01M50/103—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure prismatic or rectangular
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application discloses a secondary battery monomer, a secondary battery and an electric device. The secondary battery monomer comprises electrolyte and a positive electrode plate containing a positive electrode active material, wherein the molecular formula of the positive electrode active material is Li a Ni b Co c M1 d M2 e O f A g The electrolyte contains the vinyl disulfate and the derivative thereof, wherein the content of the vinyl disulfate and the derivative thereof accounting for x percent of the total mass of the electrolyte is more than or equal to 0.05 and less than or equal to c+ (x/10) and less than or equal to 0.15. The application can obviously improve the cycle performance and storage stability of the secondary battery monomer through the common relation between the content of the ethylene disulfate and the derivatives thereof in the electrolyte and the cobalt atom number in the molecules of the positive electrode active materialSex.

Description

Secondary battery cell, secondary battery, and electricity using device
Technical Field
The application belongs to the technical field of batteries, and particularly relates to a secondary battery monomer, a secondary battery and an electric device.
Background
In recent years, new energy automobiles are vigorously developed, a battery driving system is a main factor influencing the performance and cost of the new energy automobiles, and a secondary battery becomes a preferred scheme of a power supply in the battery driving system of the current new energy automobiles due to the characteristics of high energy density, low memory effect, high working voltage and the like.
With the expansion of market demands of electronic products and the development of power and energy storage equipment, the requirements of people on secondary batteries are continuously improved, and the development of secondary batteries with better performance is urgent. However, the charge and discharge performance of the secondary battery is still to be improved.
Disclosure of Invention
In view of the above problems, the present application provides a secondary battery cell, a secondary battery, and an electric device, which aim to solve the technical problems of how to improve the cycle performance and storage performance of the secondary battery.
In a first aspect, an embodiment of the present application provides a secondary battery cell, including an electrolyte and a positive electrode sheet, where the positive electrode sheet contains a positive electrode active material, and the molecular formula of the positive electrode active material is Li a Ni b Co c M1 d M2 e O f A g Wherein M1 comprises at least one of Mn and Al, M2 comprises at least one of Si, ti, mo, V, ge, se, zr, nb, ru, pd, sb, ce, te and W, A comprises at least one of F, N, P and S, a is 0.8.ltoreq.a.ltoreq.1.2, 0<b<0.98，0≤c<0.1，0<d<0.5，0≤e≤0.5，0≤f≤2，0≤g≤2，b+c+d+e＝1，f+g＝2；
The electrolyte contains the ethylene disulfate and the derivatives thereof, wherein the content of the ethylene disulfate and the derivatives thereof accounting for x percent of the total mass of the electrolyte is more than or equal to 0.05 and less than or equal to c+ (x/10) and less than or equal to 0.15.
The relation between the content of the vinyl disulfate and the derivative thereof in the electrolyte and the cobalt atom number in the positive electrode active material molecule is designed, namely, the sum of (x/10) and c is 0.05-0.15, and in the numerical range, the vinyl disulfate and the derivative thereof can be well formed into a film on the surface of a positive electrode plate as an additive of the electrolyte, so that the interface of the positive electrode plate is stabilized, and the cycle life is improved; therefore, the embodiment of the application can obviously improve the cycle performance and the high-temperature storage stability of the secondary battery monomer through the common relation between the content of the vinyl disulfate and the derivative thereof and the cobalt atom number in the molecule of the positive electrode active material.
In one embodiment, 0.11.ltoreq.c+ (x/10).ltoreq.0.15;
and/or 0.5.ltoreq.x.ltoreq.1.0, 0.04< c <0.1.
In the numerical range, not only can the structural stability of the positive electrode active material be improved by utilizing the effect of cobalt, but also the vinyl disulfate and the derivative thereof can better form a good protective film on the surface of the positive electrode plate so as to stabilize the interface of the positive electrode plate, thereby further obviously improving the cycle performance and the high-temperature storage performance of the secondary battery monomer.
In one embodiment, the positive electrode sheet contains a positive electrode active material layer having a compacted density of P g/cm 3 And 24.ltoreq.P/{ c+ (x/10) }.ltoreq.65.
The ratio relation between the compaction density P and { c+ (x/10) } of the positive electrode active material layer is used for satisfying 24-65, so that the initial direct current internal resistance of the secondary battery monomer is further reduced on the basis of improving the cycle performance and the high-temperature storage stability of the secondary battery, and the secondary battery monomer can have better power performance.
In one embodiment, 24.ltoreq.P/(c+x/10). Ltoreq.34.
P/{ c+ (x/10) } is in the range of 24 to 34, and the secondary battery cell can have better cycle performance, high-temperature storage property and power performance.
In one embodiment, p=3.3 to 3.6.
The positive electrode active material layer has a compacted density of 3.3-3.6 g/cm 3 In the range, the charge and discharge performance of the secondary battery monomer can be further improved, so that the secondary battery monomer has better cycle life.
In one embodiment, the electrolyte further comprises fluoroethylene carbonate and electrolyte salt, wherein the fluoroethylene carbonate accounts for y percent of the total mass of the electrolyte 1 The electrolyte salt accounts for y percent of the total mass of the electrolyte 2 ％，y 1 ＞0，y 2 > 0, and 0<y 1 +y 2 ≤15。
The fluoroethylene carbonate is used as an electrolyte additive, so that a better solid electrolyte interface film (SEI film) can be formed on the surface of the pole piece, the low-temperature performance of the electrolyte can be improved, and the combination of the fluoroethylene carbonate and the electrolyte salt in the range can form proper viscosity of the electrolyte, so that the ion migration speed of the electrolyte salt is high, and the charge and discharge performance of the secondary battery monomer is comprehensively improved.
In one embodiment, 0<y 1 ≤2.5。
The fluoroethylene carbonate can further improve the stability of the electrolyte within the above range.
In one embodiment, 0.2.ltoreq.y 1 /x≤4.0。
The fluoroethylene carbonate and the ethylene disulfate with the proportion can further improve the storage life of the secondary battery monomer on the basis of improving the cycle performance of the secondary battery monomer.
In one embodiment, the electrolyte salt comprises at least one of lithium fluorosulfonyl imide salt and lithium fluorosulfonate salt, wherein the percentage of the lithium fluorosulfonyl imide salt in the total mass of the electrolyte is y 21 The percentage content of the lithium fluorosulfonate in the total mass of the electrolyte is y 22 ％，y 21 ≥0，y 22 ≥0，y 21 And y 22 Not at the same time 0, and 0<y 1 +y 21 +y 22 ≤15。
The fluoroethylene carbonate, the lithium fluorosulfonyl imide salt and the lithium fluorosulfonate salt are matched in the range, so that the secondary battery monomer has better charge and discharge performance and safety.
In one embodiment, 0<y 21 ≤14。
The lithium fluorosulfonyl imide salt can improve the power of the secondary battery cell well within the above range.
In one embodiment, 1.ltoreq.y 21 /x≤28。
The lithium fluorosulfonyl imide salt and the vinyl disulfate in the above-mentioned ratio range can further improve the power of the secondary battery cell on the basis of improving the cycle performance of the secondary battery cell.
In one embodiment, 0<y 22 ≤1。
The lithium fluorosulfonate within the above range can improve the power of the secondary battery cell well.
In one embodiment, 0.001. Ltoreq.y 22 /x≤2.0。
The lithium fluorosulfonate and the vinyl disulfate in the above-mentioned ratio range can further improve the power of the secondary battery cell on the basis of improving the cycle performance and the storage performance of the secondary battery cell.
In one embodiment, 0.5.ltoreq.y 21 /y 1 ≤48。
The lithium fluorosulfonyl imide salt and fluoroethylene carbonate in the above-described ratio ranges can further improve the power and life of the secondary battery cell.
In one embodiment, 0.036.ltoreq.x/(y) 21 +y 22 )≤1.0。
The ratio of the amount of vinyl disulfate to the total amount of lithium fluorosulfonate and lithium fluorosulfonyl imide can further improve the lifetime of the secondary battery cell.
In one embodiment, 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15；
Alternatively, 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15，0.5≤y 21 /y 1 ≤37.5；
Alternatively, 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15，0.5≤y 21 /y 1 ≤37.5，0.05≤x/(y 21 +y 22 )≤0.12。
The lower content of nickel in the positive electrode active material molecule is 0<When b is less than or equal to 0.7, the use voltage of the secondary battery monomer is higher, and the content (y) of the lithium fluorosulfonyl imide salt in the electrolyte can be properly reduced 21 Smaller) to further improve the storage performance of the secondary battery cell.
In one embodiment, the molecular formula of the vinyl disulfate and its derivatives is shown in formula I below:
in the formula I, R 1 And R is 2 And are independently selected from hydrocarbon chains containing 1-5 carbons.
The combination of the vinyl disulfate with the derivative and the positive electrode active material can well improve the cycle performance and the high-temperature storage performance of the secondary battery.
In one embodiment, R 1 And R is 2 Are CH. The structure of the vinyl disulfate with the structure is simple and is easy to obtain.
In a second aspect, embodiments of the present application provide a secondary battery comprising the secondary battery cell of the first aspect of embodiments of the present application.
By adopting the secondary battery monomer provided by the embodiment of the application, the secondary battery has good cycle performance and high-temperature storage performance.
In a third aspect, embodiments of the present application provide an electrical device, including the secondary battery cell of the first aspect of the embodiments of the present application and/or the secondary battery provided in the second aspect of the embodiments of the present application.
By adopting the secondary battery monomer and/or the secondary battery provided by the embodiment of the application, the power utilization device has good cycle performance and high-temperature storage performance, and can work better.
The foregoing description is only an overview of the present application, and is intended to be implemented in accordance with the teachings of the present application in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present application more readily apparent.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:
Fig. 1 is a schematic structural view of an embodiment of a secondary battery cell according to an embodiment of the present application;
fig. 2 is an exploded view of the secondary battery cell shown in fig. 1;
FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application;
FIG. 4 is a schematic structural view of a battery pack according to an embodiment of the present application;
fig. 5 is an exploded view of the battery pack of fig. 4;
FIG. 6 is a schematic diagram of an embodiment of an electrical device including a secondary battery as a power source according to an embodiment of the present application;
reference numerals illustrate:
10-secondary battery cell; 11-a housing; 12-a top cap assembly; 13-an electrode assembly; 20-battery module; 30-battery pack; 31-upper box body; 32-lower box.
Detailed Description
Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description of the application and the claims and the description of the drawings above are intended to cover a non-exclusive inclusion.
In the description of embodiments of the present application, the technical terms "first," "second," and the like are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
In the description of the embodiments of the present application, the term "plurality" means two or more (including two), and similarly, "plural sets" means two or more (including two), and "plural sheets" means two or more (including two). "at least one" means more than one (including one, two, three, etc.).
In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.
In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like should be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.
With the increasing decrease of traditional energy resources, new energy storage is increasingly emphasized. Among them, the secondary battery has been attracting attention due to its high energy density, high theoretical capacity, good cycle stability and environmental protection characteristics. The secondary battery can be applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, and is widely applied to the field of electric vehicles such as electric bicycles, electric motorcycles, electric automobiles and the like. With the continuous expansion of the application field of secondary batteries as power batteries, the market demand of the secondary batteries is also continuously expanding, and the performance requirements of the secondary batteries are also higher and higher.
The positive electrode active material used in the secondary battery generally contains cobalt (Co), which can improve the structural stability of the positive electrode active material, but if the content of cobalt in the positive electrode active material is too much, the cycle performance of the secondary battery may be lowered instead after dissolution.
The ethylene bisulfate is generally used as an electrolyte additive in the electrolyte, can form a film on the surface of the positive electrode plate, and can improve the cycle life by matching with a low-cobalt positive electrode active material system, but if the ethylene bisulfate is used in the electrolyte in excessive amount, the power of the secondary battery is reduced to a certain extent, and the cycle performance of the secondary battery is further reduced.
Therefore, when the cobalt-containing positive electrode active material and the vinyl disulfate in the electrolyte are mated, the cobalt content or the vinyl disulfate content is too high to be good for the cyclic charge and discharge of the secondary battery, and when the cobalt-containing positive electrode active material and the vinyl disulfate content in the electrolyte are too low, the secondary battery system is not stable.
Based on the above consideration, in order to overcome the defect of the secondary battery performance, the embodiment of the application designs a secondary battery monomer based on a specific relation between the content of the vinyl disulfate in the electrolyte and the cobalt atom number in the molecule of the positive electrode active material, which not only can improve the cycle performance of the secondary battery monomer, but also can ensure that the secondary battery monomer has good stable storage performance. The following technical scheme is proposed.
Secondary battery cell
In a first aspect, an embodiment of the present application provides a secondary battery cell including an electrolyte and a positive electrode tab. The positive electrode plate contains positive electrode active material, and the electrolyte contains biphosphate and its derivative.
The electrolyte is a solution in which an electrolyte is dissolved, and mainly plays a role in conducting electrolyte ions in the secondary battery cell. The electrolyte of the embodiment of the application is added with the ethylene disulfate and the derivative thereof accounting for x percent of the total mass of the electrolyte, and the additives have similar performances, namely, the ethylene disulfate and the derivative thereof can form a film on the surface of the positive electrode plate to stabilize the interface of the positive electrode plate, and the cycle life of a secondary battery monomer can be improved by matching with a low-cobalt or cobalt-free positive electrode active material system.
The positive electrode active material is a material containing active ions, which release active electrons when the secondary battery cell is charged, and reform a positive electrode active material compound upon discharge to release electric energy. The molecular formula of the positive electrode active material is Li a Ni b Co c M1 d M2 e O f A g Wherein M1 comprises at least one of Mn and Al, M2 comprises at least one of Si, ti, mo, V, ge, se, zr, nb, ru, pd, sb, ce, te and W, A comprises at least one of F, N, P and S, a is 0.8.ltoreq.a.ltoreq.1.2, 0<b<0.98，0≤c<0.1，0<d<0.5, 0.ltoreq.e.ltoreq.0.5, 0.ltoreq.f.ltoreq.2, 0.ltoreq.g.ltoreq.2, b+c+d+e=1, f+g=2. The number of cobalt atoms in one molecule of the positive electrode active material can be understood as the subscript number of atoms b of cobalt element in the molecular formula of the positive electrode active material, whereas the positive electrode active material of the embodiment of the present application is a low-cobalt or cobalt-free positive electrode active material system. The positive electrode active material represented by the molecular formula can be well matched with the vinyl disulfate and the derivative thereof in the electrolyte to improve the cycle performance and the high-temperature storage performance of the secondary battery.
Specifically, the cobalt atom number in the positive electrode active material molecule is closely related to the mass percentage content of the vinyl disulfate and the derivative thereof in the electrolyte. Thus, the sum of the designs (x/10) and c of the embodiment of the present application is 0.05 to 0.15, and if the sum of the two is low (less than 0.05), the system of the secondary battery cell is easily unstable, affecting the cycle performance, and if the sum of the two is too high (more than 0.15), the cycle performance of the secondary battery is conversely lowered. In the numerical range, the film can be well formed on the surface of the positive pole piece by utilizing the action of the vinyl disulfate and the derivative thereof, so that the interface of the positive pole piece is stabilized, and the cycle life is improved; the embodiment of the application can obviously improve the cycle performance of the secondary battery monomer in the range, and the secondary battery monomer also has good high-temperature storage performance.
In one embodiment, the percentage content of the vinyl disulfate and the derivatives thereof in the total mass of the electrolyte is x% based on the total mass of the electrolyte; and the number of cobalt atoms in one molecule of the positive electrode active material is c, the secondary battery cell is set so as to satisfy: c+x/10 is more than or equal to 0.05 and less than or equal to 0.15. In an example, in the total content x% of the vinyl disulfate and its derivatives based on the total mass of the electrolyte, x may be 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 0.9, 1.0, etc., the number of cobalt atoms c in one molecule of the positive electrode active material may be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, etc., and the sum of x/10 and c may be 0.05, 0.06, 0.08, 0.09, 0.10, 0.12, 0.14, 0.15, etc.
Further, c+ (x/10) is more than or equal to 0.11 and less than or equal to 0.15. Such a numerical range improves the cycle efficiency better.
Further, x is more than or equal to 0.5 and less than or equal to 1.0, and c is more than or equal to 0.04 and less than or equal to 0.1. The cobalt can improve the structural stability of the positive electrode active material, so that the embodiment of the application adopts the positive electrode active material with low cobalt element, and the secondary battery system has good stability. Through the c and x in the range, not only can the structural stability of the anode active material be improved by utilizing the low cobalt atomic number, but also the good protective film can be better formed on the surface of the anode plate by promoting the vinyl disulfate and the derivatives thereof to stabilize the interface of the anode plate, so that the cycle performance and the high-temperature storage performance of the secondary battery monomer can be further obviously improved.
In one embodiment, the positive electrode sheet contains a positive electrode active material layer having a compacted density of P g/cm 3 And 24.ltoreq.P/{ c+ (x/10) }.ltoreq.65. The compacted density refers to the ratio of the surface density formed by coating the surface of a current collector with positive electrode slurry to the thickness of the current collector in the design process of the secondary battery, and the unit is: g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the In an example, the ratio of the positive electrode active material layer density to the sum of c+ (x/10) of the embodiments of the present application satisfies 24 to 65, such as 24, 25, 28, 30, 34, 38, 40, 42, 45, 46, 50, 52, 54, 56, 58, 60, 62, 65, etc.
The secondary battery monomer provided by the embodiment of the application has the advantages that c+x/10 is more than or equal to 0.05 and less than or equal to 0.15, x is more than or equal to 0 and less than or equal to 1.0, c is more than or equal to 0 and less than or equal to 0.1, and P/(c+x/10) is more than or equal to 24 and less than or equal to 65; the relation of the compaction density P and the ratio of c+x/10 of the positive electrode active material layer is utilized, so that the initial direct current internal resistance (DCR) of the secondary battery monomer is further reduced on the basis of improving the cycle performance and the high-temperature storage performance of the secondary battery, and the secondary battery monomer can have better power performance.
In one embodiment, the secondary battery cell satisfies: c+x/10 is more than or equal to 0.11 and less than or equal to 0.15, x is more than or equal to 0.5 and less than or equal to 1.0, c is more than or equal to 0.04 and less than or equal to 0.1, and P/(c+x/10) is more than or equal to 24 and less than or equal to 34. Under this condition, the secondary battery cell can have better cycle performance, high-temperature storage property and power performance.
In one embodiment, p=3.3 to 3.6. In an example, the positive electrode active material layer of the embodiment of the present application may have a solid density of 3.3g/cm 3 、3.4g/cm 3 、3.5g/cm 3 、3.6g/cm 3 Etc. The secondary battery monomer satisfies: c+x/10 is more than or equal to 0.11 and less than or equal to 0.15 and 0.5<x≤1.0，0.04<c<P=3.3-3.6, and P/(c+x/10) is not less than 24 and not more than 34. Such conditions may further improve the charge and discharge performance of the secondary battery cell, thereby having a better cycle life.
In one embodiment, the electrolyte further comprises fluoroethylene carbonate and electrolyte salt, wherein the content of the fluoroethylene carbonate in the total mass of the electrolyte is y 1 The electrolyte salt accounts for y percent of the total mass of the electrolyte 2 ％，y 1 ＞0，y 2 > 0, and 0<y 1 +y 2 ≤15。
The fluoroethylene carbonate is used as an electrolyte additive, so that a better solid electrolyte interface film can be formed on the surface of the pole piece, the low-temperature performance of the electrolyte can be improved, generally, the electrolyte needs to have lower viscosity during working so that ions of electrolyte salts can migrate better, and the fluoroethylene carbonate and the electrolyte salts in the range can form proper electrolyte viscosity by combining, so that the ion migration speed of the electrolyte salts is high, and the charge and discharge performance and safety of the secondary battery monomers are comprehensively improved.
In one embodiment, 0<y 1 Less than or equal to 2.5; in an example, the mass percent y of fluoroethylene carbonate in the electrolyte based on the total mass of the electrolyte 1 % may be 0.5%, 0.8%, 1%, 1.5%, 1.8%, 2%, 2.2%, 2.5%. For example, the secondary battery monomer electrolyte satisfies, 0<y 1 ≤2.5，y 2 ＞0，0<y 1 +y 2 And is less than or equal to 15. Such an electrolyte has better stability.
In one embodiment, 0.2.ltoreq.y 1 X is less than or equal to 4.0. In an example, the mass percent y of fluoroethylene carbonate in the electrolyte based on the total mass of the electrolyte 1 The ratio of% to x% mass percent of the total mass of the electrolyte may be 0.2, 0.5, 0.8, 1.0, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, etc. The fluoroethylene carbonate and the electrolyte salt in the above proportions can further improve the storage life of the secondary battery cell.
In one embodiment, 0<y 1 ≤2.0，0.2≤y 1 X is less than or equal to 2.0. Such an electrolyte has better stability.
In one embodiment, the electrolyte salt comprises at least one of lithium fluorosulfonyl imide salt and lithium fluorosulfonate salt, wherein the percentage of the lithium fluorosulfonyl imide salt in the total mass of the electrolyte solution is y 21 The percentage content of the lithium fluorosulfonate in the total mass of the electrolyte is y 22 ％，y 21 ≥0，y 22 ≥0，y 21 And y 22 Not at the same time 0, and 0<y 1 +y 21 +y 22 And is less than or equal to 15. In an exemplary embodiment, y 1 +y 21 +y 22 May be 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 9, 10, 12, 14, 15, etc.; the fluoroethylene carbonate, the lithium fluorosulfonyl imide salt and the lithium fluorosulfonate salt are matched in the range, so that the secondary battery monomer has better charge and discharge performance and safety.
In one embodiment, 0<y 21 And is less than or equal to 14. In an example, the mass percent y of the lithium fluorosulfonyl imide salt in the electrolyte based on the total mass of the electrolyte 21 % may be 1%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, 10%, 12%, 14%, etc.
Specifically, the secondary battery monomer electrolyte satisfies, 0<y 1 ≤2.5，y 2 ≥0，0<y 21 ≤14，0<y 1 +y 21 +y 22 And is less than or equal to 15. Under the above conditions, the power of the secondary battery cell is further improved on the basis of improving the cycle performance and the high-temperature storage performance of the secondary battery cell.
In one embodiment, 1.ltoreq.y 21 X is less than or equal to 28. In an example, the mass percent y of the lithium fluorosulfonyl imide salt in the electrolyte based on the total mass of the electrolyte 21 The ratio of% to x% mass percent of the total mass of the electrolyte may be 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 8.0, 10, 11, 12, 14, 15, 20, 22, 24, 25, 26, 28, etc. The lithium fluorosulfonyl imide salt and the vinyl disulfate in the above-mentioned ratio range can further improve the power of the secondary battery cell on the basis of improving the cycle performance and the storage performance of the secondary battery cell.
In one embodiment, 0<y 22 And is less than or equal to 1. In an example, the mass percentage y of the lithium fluorosulfonate in the electrolyte based on the total mass of the electrolyte 22 % may be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%0.55%, 0.6%, 0.65%, 0.7%, 0.8%, 0.9%, 1%, etc.
Specifically, the secondary battery monomer electrolyte satisfies, 0<y 1 ≤2.5，y 2 ≥0，0<y 21 ≤14，0<y 22 ≤1，0<y 1 +y 21 +y 22 And is less than or equal to 15. The power of the second battery cell can be further improved on the basis of improving the cycle performance and the high-temperature storage performance of the secondary battery cell under such conditions.
In one embodiment, 0.001. Ltoreq.y 22 X is less than or equal to 2.0. In an example, the mass percentage y of the lithium fluorosulfonate in the electrolyte based on the total mass of the electrolyte 22 The ratio of% to x% by mass of the total mass of the electrolyte may be 0.001, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 1, 1.2, 1.5, 2, etc. The lithium fluorosulfonate and the vinyl disulfate in the above-mentioned ratio range can further improve the power of the secondary battery cell on the basis of improving the cycle performance and the storage performance of the secondary battery cell.
In one embodiment, 0.5.ltoreq.y 21 /y 1 48, specifically, the secondary battery monomer satisfies: 0<y 1 ≤2.5，0<y 21 ≤14，0<y 22 ≤1.0，0.5≤y 1 /x≤4.0，1≤y 21 /x≤28，0.001≤y 22 /x≤2.0，0.5≤y 21 /y 1 And is less than or equal to 48. Under the above conditions, the power and the service life of the secondary battery monomer can be further improved on the basis of improving the cycle performance and the storage performance of the secondary battery monomer.
In one embodiment, 0.036.ltoreq.x/(y) 21 +y 22 ) And less than or equal to 1.0, and in specific examples, the specific examples can be 0.036, 0.04, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 and the like. The ratio of the amount of vinyl disulfate to the total amount of lithium fluorosulfonate and lithium fluorosulfonyl imide can further improve the lifetime of the secondary battery cell.
In one embodiment, the positive electrode active material Li a Ni b Co c M1 d M2 e O f A g The number of nickel atoms b in the molecule can be understood as the number of subscript atoms of nickel element in the molecular formula of the positive electrode active material. The nickel can improve the volume energy density of the positive electrode active material, and the performance of the secondary battery monomer can be improved by combining the different value ranges of the nickel atoms in the molecules of the positive electrode active material with the matching of the lithium fluoro-sulfimide salt.
Specifically, the nickel content in the positive electrode active material molecule is low, such as 0<When b is less than or equal to 0.7, the use voltage of the secondary battery monomer is higher, and the content (y) of the lithium fluorosulfonyl imide salt in the electrolyte can be properly reduced 21 Smaller) to further improve the storage performance of the secondary battery cell.
In one embodiment, the number of nickel atoms in one molecule of the positive electrode active material is b, and 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 And x.ltoreq.15, wherein b may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, etc.
Alternatively, 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15，0.5≤y 21 /y 1 And is less than or equal to 37.5. Further, 0.2<y 1 ≤2.5，0<y 22 ≤1.0，0.2≤y 1 /x≤0.4，1≤y 22 /x≤2.0。
Alternatively, 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15，0.5≤y 21 /y 1 ≤37.5，0.05≤x/(y 21 +y 22 ) Less than or equal to 0.12. Further, 0.2<y 1 ≤2.5，0<y 22 ≤1.0，0.2≤y 1 /x≤0.4，1≤y 22 /x≤2.0。
The cathode active material molecule with lower nickel atom number and the lithium fluoro-sulfonimide salt with lower content are matched, so that the storage life of the secondary battery monomer can be further prolonged on the basis of improving the cycle performance and the high-temperature storage performance of the secondary battery monomer.
In one embodiment, the molecular formula of the vinyl disulfate and its derivatives in the electrolyte is shown in formula I below:
in the formula I, R 1 And R is 2 And are independently selected from hydrocarbon chains containing 1-5 carbons.
Specifically, R 1 And R is 2 May be the same or different, and are each independently selected from hydrocarbon chains having 1 to 5 carbons, and may be selected, for example, as follows:
etc.; wherein R is 1 And R is 2 The tertiary carbon atoms (tertiary carbon atoms) of (a) are linked to each other and then at R 1 Or R is 2 The positions are connected with adjacent other atoms to form two ring structures in the formula I. The combination of the double-sulfuric acid vinyl ester and the derivative thereof with the positive electrode active material can well improve the cycle performance and the high-temperature storage performance of the secondary battery.
In one embodiment, the lithium fluorosulfonyl imide salt in the electrolyte is of the molecular type LiN (SO) 2 R 3 )(SO 2 R 4 )，R 3 、R 4 Each independently represents F or C n F 2n+1 N is an integer from 1 to 10, optionally the lithium fluorosulfonyl imide salt comprises lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, or a combination thereof.
In one embodiment, the lithium fluorosulfonate in the electrolyte has the formula LiSO 3 R 5 ，R 5 Represents F, a partially fluorinated or fully fluorinated C1-C10 alkyl group, optionally, the lithium fluorosulfonate comprises lithium fluorosulfonate, lithium trifluoromethanesulfonate, or a combination thereof.
The electrolyte salt plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The electrolyte includes an electrolyte salt and a solvent. For the secondary battery to be a lithium ion battery, the electrolyte salt may be at least one selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorooxalato phosphate, and lithium tetrafluorooxalato phosphate. For the secondary battery being a sodium ion battery, the corresponding electrolyte salt is replaced with a sodium salt.
In some embodiments, the electrolyte solution includes a solvent in addition to the vinyl disulfate and derivatives thereof, and the fluoroethylene carbonate and electrolyte salt described above in formula I. Specifically, the solvent may be at least one selected from ethylene carbonate, propylene carbonate, methylethyl 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, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. In some embodiments, the electrolyte may also add other additives.
In some embodiments, the secondary battery cell typically includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. In the process of charging and discharging the secondary battery monomer, active ions are inserted and separated back and forth between the positive electrode plate and the negative electrode plate. The electrolyte in the electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film.
In some embodiments, a positive electrode tab includes a positive electrode current collector and a positive electrode active material layer bonded on the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material, and when the secondary battery monomer is a lithium ion battery monomer, the positive electrode active material is a lithium-containing material, and when the secondary battery monomer is a sodium ion battery monomer, the positive electrode active material is a sodium-containing material. With positive active material as Li a Ni b Co c M1 d M2 e O f A g For example, the relationship between the number of cobalt atoms in the molecular formula of the positive electrode active material and the content of vinyl disulfate in the electrolyte can improve the cycle performance and the storage performance of the secondary battery monomer of the application.
In some embodiments, the current collector of the positive electrode sheet, also known as a positive electrode current collector, may be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.
In some embodiments, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate resin. Further, the positive electrode active material layer may further optionally include a conductive agent. As an 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.
In some embodiments, the negative electrode tab includes a negative electrode current collector and a negative electrode film layer coupled to the negative electrode current collector. Wherein the negative electrode film layer contains a negative electrode active material, and the negative electrode active material can be a negative electrode active material for a battery known in the art. As an example, the anode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
In some embodiments, the current collector of the negative electrode tab is also called a negative electrode current collector, and the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.
In some embodiments, the negative electrode film layer further optionally includes a binder. The binder is at least one selected from styrene butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid and carboxymethyl chitosan. Further, the negative electrode film layer may further optionally include a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. The anode active material layer may further optionally include other auxiliary agents, such as a thickener (e.g., sodium carboxymethyl cellulose), and the like.
In some embodiments, the type of the separator is not particularly limited, and may be selected according to actual needs. Specifically, the isolating film may be one or more selected from polyethylene film, polypropylene film, polyvinylidene fluoride film and their multilayer composite film.
In some embodiments, the shape of the secondary battery cell is not particularly limited, and may be cylindrical, square, or any other shape. A secondary battery cell 10 of a square structure as shown in fig. 1.
In some embodiments, as shown in fig. 2, the exterior package of the secondary battery cell 10 may include a case 11 and a top cap assembly 12. The housing 11 may include a bottom plate and a side plate coupled to the bottom plate, the bottom plate and the side plate enclosing to form a receiving chamber. The housing 11 has an opening communicating with the accommodation chamber, and the cap assembly 12 is for covering the opening to close the accommodation chamber. The positive electrode sheet, the separator and the negative electrode sheet contained in the secondary battery monomer of the embodiment of the application can form the electrode assembly 13 through a winding process and/or a lamination process. The electrode assembly 13 is enclosed in the receiving chamber. The electrolyte is impregnated in the electrode assembly 13. The number of the electrode assemblies 13 included in the secondary battery cell 10 may be one or more, and may be adjusted according to actual needs.
The preparation method of the secondary battery monomer can comprise the following steps: the negative electrode plate, the isolating film, the positive electrode plate and the electrolyte are assembled into the secondary battery monomer of the embodiment of the application. The secondary battery monomer of the application embodiment can be prepared by assembling the negative electrode plate, the isolating film, the positive electrode plate and the electrolyte according to the content relation between the content of the vinyl disulfate and the derivative thereof in the electrolyte and the cobalt atom number in the molecules of the positive electrode active material. The preparation method has the advantages of simple process and low preparation cost, and the obtained secondary battery monomer has good cycle performance and high-temperature storage performance.
The specific material types of the negative electrode plate, the isolating film, the positive electrode plate and the electrolyte in the secondary battery monomer are set forth in detail above. The negative electrode sheet, the isolating film and the positive electrode sheet are assembled with the electrolyte to form a secondary battery monomer, and as an example, the negative electrode sheet, the isolating film and the positive electrode sheet can be formed into an electrode assembly through a winding process or a lamination process, the electrode assembly is placed in an outer package, the electrolyte is injected after being dried, and the secondary battery monomer is obtained through the procedures of vacuum packaging, standing, formation, shaping and the like.
Secondary battery
In a second aspect, an embodiment of the present application provides a secondary battery, which includes the secondary battery cell of the first aspect of the embodiment of the present application. By adopting the secondary battery monomer provided by the embodiment of the application, the secondary battery has good cycle performance and high-temperature storage performance.
In some embodiments, the secondary battery according to the embodiment of the present application may include any one of a secondary battery cell, a battery module, and a battery pack. The secondary battery cell comprises a battery shell and an electric core encapsulated in the battery shell. The shape of the secondary battery cell is not particularly limited, and may be cylindrical, square, or any other shape. A secondary battery cell 10 of a square structure as shown in fig. 1.
In some embodiments, as shown in fig. 2, the exterior package of the secondary battery cell 10 may include a case 11 and a top cap assembly 12. The housing 11 may include a bottom plate and a side plate coupled to the bottom plate, the bottom plate and the side plate enclosing to form a receiving chamber. The housing 11 has an opening communicating with the accommodation chamber, and the cap assembly 12 is for covering the opening to close the accommodation chamber. The positive electrode, separator and negative electrode sheet included in the secondary battery according to the embodiment of the present application may be formed into the electrode assembly 13 through a winding process and/or a lamination process. The electrode assembly 13 is enclosed in the receiving chamber. The electrolyte is impregnated in the electrode assembly 13. The number of the electrode assemblies 13 included in the secondary battery cell 10 may be one or more, and may be adjusted according to actual needs.
Methods for preparing secondary battery cell 10 are well known. In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet and the electrolyte may be assembled to form the secondary battery cell 10. As an example, the positive electrode sheet, the separator and the negative electrode sheet may be formed into the electrode assembly 13 through a winding process or a lamination process, the electrode assembly 13 is placed in an exterior package, dried, and then an electrolyte is injected, and the secondary battery cell 10 is obtained through the processes of vacuum packaging, standing, formation, shaping, and the like.
In some embodiments, the secondary battery includes a battery module, which is assembled from the secondary battery cells 10, that is, may contain a plurality of the secondary battery cells 10, and the specific number may be adjusted according to the application and capacity of the battery module.
In some embodiments, fig. 3 is a schematic diagram of a battery module 20 as one example. As shown in fig. 3, in the battery module 20, a plurality of secondary battery cells 10 may be sequentially arranged in the longitudinal direction of the battery module 20. Of course, the arrangement may be performed in any other way. The plurality of secondary battery cells 10 may be further fixed by fasteners.
Alternatively, the battery module 20 may further include a case having an accommodating space in which the plurality of secondary battery cells 10 are accommodated.
The battery pack of the secondary battery is assembled from the above secondary battery cells 10, that is, may contain a plurality of secondary battery cells 10, wherein a plurality of the secondary battery cells 10 may be assembled into the above battery module 20. The specific number of secondary battery cells 10 or battery modules 20 included in the secondary battery pack may be adjusted according to the application and capacity of the battery pack.
Fig. 4 and 5 are schematic views of a battery pack 30 as one example, as in the embodiment. A battery case and a plurality of battery modules 20 disposed in the battery case may be included in the battery pack 30. The battery case includes an upper case 31 and a lower case 32, the upper case 31 being for covering the lower case 32 and forming a closed space for accommodating the battery module 20. The plurality of battery modules 20 may be arranged in the battery case in any manner.
Power utilization device
In a third aspect, the embodiment of the present application further provides an electrical device, where the electrical device includes the secondary battery cell and/or the secondary battery according to the embodiment of the present application. The secondary battery may be used as a power source of an electric device, or may be used as an energy storage unit of an electric device. By adopting the secondary battery provided by the embodiment of the application, the power utilization device has good cycle performance and high-temperature storage performance, and can work better.
The electric device may be, but is not limited to, a mobile device (e.g., a cellular phone, a notebook computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc. The power utilization device can select a secondary battery cell, a battery module or a battery pack according to the use requirement.
Fig. 6 is a schematic diagram of an electrical device as one example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the high power and high energy density requirements of the power device, a battery pack or battery module may be employed.
As another example, the power consumption device may be a mobile phone, a tablet computer, a notebook computer, or the like. The electric device is required to be light and thin, and a secondary battery can be used as a power source.
Examples
Hereinafter, embodiments of the present application are described. The following examples are illustrative only and are not to be construed as limiting the application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. The preparation method of the secondary battery monomer comprises the following steps:
preparing a positive electrode plate: liNi is prepared by using methyl pyrrolidone (NMP) as solvent 0.65 Co 0.05 Mn 0.3 O 2 Carbon Nanotubes (CNT), binder (PVDF) in mass ratio 97:2:1, mixing to prepare anode slurry with the solid content of 80%; and uniformly coating the anode slurry on an aluminum foil, performing double-sided coating, fully drying, cold pressing and cutting to obtain the anode plate.
Preparing a negative electrode plate: taking water as a solvent, mixing artificial graphite, a conductive agent SP, a dispersing agent (CMC) and a binder (SBR) according to a mass ratio of 96:1:1:2, mixing to prepare cathode slurry with the solid content of 58%; and uniformly coating the anode slurry on an aluminum foil, performing double-sided coating, fully drying, cold pressing and cutting to obtain the anode plate.
Preparing an electrolyte: mixing Ethylene Carbonate (EC)/diethyl carbonate (DEC) at room temperature at a volume ratio of 1:1 to obtain a mixed solvent, and adding vinyl disulfate (R in formula I) 1 And R is 2 All are CH), lithium bis (fluorosulfonyl) imide and lithium trifluoromethane sulfonate to obtain electrolyte;
and (3) battery assembly: and stacking and winding the prepared positive pole piece and negative pole piece in the sequence of positive pole piece, isolating film and negative pole piece to form a bare cell, and then filling electrolyte to assemble the lithium ion secondary battery monomer.
Example 2
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Example 3
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Example 4
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Example 5
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Example 6
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Example 7
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Comparative example 1
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Comparative example 2
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
Comparative example 3
A secondary battery monomer comprises an electric core formed by a positive electrode plate, a separation film and a negative electrode plate, and further comprises electrolyte. Other steps of the preparation method are the same as in example 1 except that the content and parameters of the relevant components are shown in table 1.
TABLE 1
In Table 1, the positive electrode active material layer has a compacted density of P g/cm, in which the number of nickel atoms in the molecular formula of the positive electrode active material is b and the number of cobalt atoms is c 3 The content of the bis-vinyl sulfate accounting for the total mass of the electrolyte is x percent, and the content of the fluoroethylene carbonate accounting for the total mass of the electrolyte is y percent 1 The percentage content of the lithium fluorosulfonyl imide salt in the total mass of the electrolyte is y 21 The percentage content of the lithium fluorosulfonate in the total mass of the electrolyte is y 22 ％。
Performance testing
The secondary battery cells of examples 1 to 7 and comparative examples 1 to 3 described above were each subjected to the following test.
(1) Cycle performance test
The charge-discharge cycle test conditions were: the testing temperature is 60 ℃, the secondary battery monomer is discharged to 2.5V at a constant current of 1C, and the secondary battery monomer is kept stand for 10min; then, the charge was stopped with a constant current and constant voltage of 1C charged to 4.25V and a cutoff current of 0.02C, and the charge was cycled 600 times, with the first discharge capacity being C1 and the 600 th discharge capacity being C2, and the discharge capacity retention = C2/C1 was calculated according to the formula, thereby obtaining the charge-discharge capacity retention.
(2) DC internal resistance test
At 25 ℃, the secondary battery cell is charged to 4.25V at 0.33C, then discharged for half an hour at 0.5C, and left for 1 hour, the voltage at this time is recorded as V0, the voltage at this time is discharged for 30S at 4C, the voltage at this time is recorded as V1, and R is recorded as (V0-V1)/I (current corresponding to 4C), where R is the internal resistance of the battery. The smaller this value, the better the power performance of the battery.
(3) Storage performance test
Charging the secondary battery monomer to 4.3V at 60deg.C under constant current, continuously charging at constant voltage to 0.05C, and testing the volume of the secondary battery monomer by water drainage method and recording as V a The method comprises the steps of carrying out a first treatment on the surface of the Then the secondary battery monomer is put into a constant temperature box with the temperature of 60 ℃ and stored for 30 daysTaking out, at this time, the volume of the secondary battery cell was measured by a drainage method and recorded as V b . Volume expansion rate (%) = [ (V) after 30 days of storage at 60 °c b -V a )/V a ]×100％。
The results of the above test are shown in Table 2.
TABLE 2
From the test results in Table 2, it can be seen that: compared with the comparative example, the embodiment of the application can obviously improve the cycle performance and the storage stability of the secondary battery monomer and reduce the initial direct current internal resistance through the relation collocation between the content of the vinyl disulfate in the electrolyte and the cobalt atom number in the molecule of the positive electrode active material.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and are intended to be included within the scope of the appended claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims (20)

1. A secondary battery monomer comprises electrolyte and a positive electrode plate, and is characterized in that the positive electrode plate contains a positive electrode active material, and the molecular formula of the positive electrode active material is Li a Ni b Co c M1 d M2 e O f A g Wherein M1 comprises at least one of Mn and Al, and M2 comprises Si,Ti, mo, V, ge, se, zr, nb, ru, pd, sb, ce, te and W, A comprises at least one of F, N, P and S, 0.8.ltoreq.a.ltoreq.1.2, 0<b<0.98，0≤c<0.1，0<d<0.5，0≤e≤0.5，0≤f≤2，0≤g≤2，b+c+d+e＝1，f+g＝2；
The electrolyte contains vinyl disulfate and derivatives thereof, wherein the content of the vinyl disulfate and the derivatives thereof accounting for x percent of the total mass of the electrolyte is more than or equal to 0.05 and less than or equal to c+ (x/10) and less than or equal to 0.15.
2. The secondary battery cell according to claim 1, wherein 0.11.ltoreq.c+ (x/10).ltoreq.0.15;
and/or 0.5.ltoreq.x.ltoreq.1.0, 0.04< c <0.1.
3. The secondary battery cell according to claim 1 or 2, wherein the positive electrode sheet contains a positive electrode active material layer having a compacted density of P g/cm 3 And 24.ltoreq.P/{ c+ (x/10) }.ltoreq.65.
4. The secondary battery cell as claimed in claim 3, wherein 24.ltoreq.P/(c+x/10). Ltoreq.34.
5. The secondary battery cell according to claim 3 or 4, wherein p=3.3 to 3.6.
6. The secondary battery cell according to any one of claims 1 to 5, wherein the electrolyte further comprises fluoroethylene carbonate and an electrolyte salt, the fluoroethylene carbonate being present in an amount of y based on the total mass of the electrolyte 1 The electrolyte salt accounts for y percent of the total mass of the electrolyte solution 2 ％，y 1 ＞0，y 2 > 0, and 0<y 1 +y 2 ≤15。
7. The secondary battery cell as claimed in claim 6, wherein 0<y 1 ≤2.5。
8. The secondary battery cell according to claim 6 or 7, wherein 0.2.ltoreq.y 1 /x≤4.0。
9. The secondary battery cell according to any one of claims 6 to 8, wherein the electrolyte salt comprises at least one of a lithium fluorosulfonyl imide salt and a lithium fluorosulfonate salt, and the percentage content of the lithium fluorosulfonyl imide salt in the total mass of the electrolyte solution is y 21 The percentage content of the lithium fluorosulfonate in the total mass of the electrolyte is y 22 ％，y 21 ≥0，y 22 ≥0，y 21 And y 22 Not at the same time 0, and 0<y 1 +y 21 +y 22 ≤15。
10. The secondary battery cell as claimed in claim 9, wherein 0<y 21 ≤14。
11. The secondary battery cell according to claim 9 or 10, wherein 1.ltoreq.y 21 /x≤28。
12. The secondary battery cell according to any one of claims 9 to 11, wherein 0<y 22 ≤1。
13. The secondary battery cell according to any one of claims 9 to 12, wherein 0.001.ltoreq.y 22 /x≤2.0。
14. The secondary battery cell according to any one of claims 9 to 13, wherein 0.5.ltoreq.y 21 /y 1 ≤48。
15. The secondary battery cell according to any one of claims 9 to 14, wherein 0.036.ltoreq.x/(y) 21 +y 22 )≤1.0。
16. The secondary battery cell according to any one of claims 9 to 15, whereinIn that 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15；
Alternatively, 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15，0.5≤y 21 /y 1 ≤37.5；
Alternatively, 0<b≤0.7，0<y 21 ≤7.5，1≤y 21 /x≤15，0.5≤y 21 /y 1 ≤37.5，0.05≤x/(y 21 +y 22 )≤0.12。
17. The secondary battery cell according to any one of claims 1 to 16, wherein the vinyl disulfate and derivatives thereof have the general molecular formula I:
in the formula I, R 1 And R is 2 And are independently selected from hydrocarbon chains containing 1-5 carbons.
18. The secondary battery cell as claimed in claim 17, wherein R 1 And R is 2 Are CH.
19. A secondary battery comprising the secondary battery cell according to any one of claims 1 to 18.
20. An electric device comprising the secondary battery cell according to any one of claims 1 to 18 and/or the secondary battery according to claim 19.
CN202310601669.5A 2023-05-25 2023-05-25 Secondary battery cell, secondary battery, and electricity using device Pending CN116759711A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117254118A (en) * 2023-11-17 2023-12-19 宁德时代新能源科技股份有限公司 Secondary battery and electricity utilization device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117254118A (en) * 2023-11-17 2023-12-19 宁德时代新能源科技股份有限公司 Secondary battery and electricity utilization device

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