Secondary battery and electrical apparatus

Abstract

A secondary battery and an electrical apparatus, which belong to the technical field of batteries. The secondary battery comprises an electrolyte and an electrode piece; the electrode piece comprises an electrode active material layer; the electrode active material layer comprises a binder with alkali metal ions, the amount of the alkali metal ions in the binder is represented by A mol, the amount of the alkali metal ions in the electrolyte is represented by D mol, and the ratio of A to D is 0.01-1.5. Consequently, the cost of the secondary battery is effectively reduced while still allowing the secondary battery to have excellent cycle performance.

Description

Secondary batteries and electrical devices

[0001] Cross-references

[0002] This application refers to Chinese Patent Application No. 202311633137.6, filed on December 1, 2023, entitled “Secondary Battery and Electrical Device,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a secondary battery and an electrical device. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0005] Secondary batteries, with their advantages of high operating voltage, reusability, and lack of memory effect, are finding increasing application. For example, they have become the primary power source for electric vehicles, mobile phones, laptops, cameras, and portable power banks. However, their high cost makes reducing it a pressing technical challenge.

[0006] Summary of the Invention

[0007] Based on this, the present application provides a secondary battery and an electrical device, aiming to reduce the cost of the secondary battery while ensuring that the secondary battery still has excellent cycle performance.

[0008] In a first aspect of the present application, a secondary battery is provided, comprising an electrolyte and an electrode plate, wherein the electrode plate comprises an electrode active material layer, the electrode active material layer comprises a binder containing alkali metal ions, the amount of alkali metal ions in the binder is A mol, the amount of alkali metal ions in the electrolyte is D mol, and the ratio of A to D is 0.01-1.5.

[0009] In the above embodiment, the binder containing alkali metal ions can not only play a bonding role, but also serve as a source of alkali metal ions, wherein the alkali metal ions can be dissociated in the electrolyte to provide active ions for the secondary battery. Therefore, the binder containing alkali metal ions can replace part of the alkali metal salt, and the ratio of A to D is controlled within the range of 0.01-1.5, which effectively reduces the amount of alkali metal salt used in the electrolyte, thereby effectively reducing the cost of the secondary battery, while ensuring that the secondary battery still has excellent cycle performance.

[0010] In some embodiments, the ratio of A to D is 0.1-1.

[0011] In some embodiments, the concentration of the alkali metal salt in the electrolyte is 0.4 mol / L-1.2 mol / L.

[0012] In some embodiments, based on the mass of the electrode active material layer, the mass percentage of the binder containing alkali metal ions is 0.1%-5%.

[0013] In some embodiments, based on the mass of the electrode active material layer, the mass percentage of the binder containing alkali metal ions is 0.5%-2%.

[0014] In some embodiments, based on the mass of the binder containing alkali metal ions, the mass percentage of the alkali metal element in the binder containing alkali metal ions is 3%-8.9%.

[0015] In some embodiments, the number average molecular weight of the binder containing alkali metal ions is 3,000-3,000,000.

[0016] In some embodiments, the number average molecular weight of the binder containing alkali metal ions is 100,000-2,000,000.

[0017] In some embodiments, the binder containing alkali metal ions includes one or more of a binder containing lithium ions, a binder containing sodium ions, and a binder containing potassium ions.

[0018] In some embodiments, the lithium ion-containing binder includes one or more of lithium polyacrylate, lithium alginate, and lithium carboxymethyl cellulose.

[0019] In some embodiments, the sodium ion-containing binder includes one or more of sodium polyacrylate, sodium alginate, and sodium carboxymethyl cellulose.

[0020] In some embodiments, the potassium ion-containing binder includes one or more of potassium polyacrylate, potassium alginate, and potassium carboxymethyl cellulose.

[0021] In some embodiments, the electrolyte includes a film-forming additive, and the mass percentage of the film-forming additive is 0.005%-5% based on the mass of the electrolyte.

[0022] In some embodiments, the film-forming additive includes one or more of an unsaturated ester additive, a sulfur-containing organic additive, and an inorganic compound additive.

[0023] In some embodiments, the unsaturated ester additive includes one or more of vinylene carbonate and fluoroethylene carbonate.

[0024] In some embodiments, the sulfur-containing organic additive includes one or more of ethylene sulfite and propylene sulfite.

[0025] In some embodiments, the inorganic compound additive includes one or more of SO2, CO2, Na2CO3, Na2SO3, K2CO3 and Li2CO3.

[0026] In some embodiments, the alkali metal salt includes one or more of a lithium salt, a sodium salt, and a potassium salt.

[0027] In some embodiments, the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0028] In some embodiments, the sodium salt includes one or more of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium difluorophosphate, sodium difluorooxalatoborate, sodium dioxalatoborate, sodium difluorodioxalatophosphate, and sodium tetrafluorooxalatophosphate.

[0029] In some embodiments, the potassium salt includes one or more of potassium hexafluorophosphate, potassium tetrafluoroborate, potassium perchlorate, potassium hexafluoroarsenate, potassium bisfluorosulfonyl imide, potassium bistrifluoromethanesulfonyl imide, potassium trifluoromethanesulfonate, potassium difluorophosphate, potassium difluorooxalatoborate, potassium dioxalatoborate, potassium difluorodioxalatophosphate and potassium tetrafluorooxalatophosphate.

[0030] In some embodiments, the electrode active material layer further includes an electrode active material and a conductive agent, and the electrode active material includes a positive electrode active material or a negative electrode active material.

[0031] A second aspect of the present application provides an electrical device comprising the secondary battery described in the first aspect of the present application.

[0032] The electric device of the present application includes the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery.

[0033] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered as limiting the scope of the disclosed application, the embodiments or examples currently described, and any of the best modes currently understood for these applications. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the accompanying drawings:

[0035] FIG1 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0036] FIG. 2 is an exploded view of the battery cell according to one embodiment of the present application shown in FIG. 1 .

[0037] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0038] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0039] FIG5 is an exploded view of the battery pack shown in FIG4 according to an embodiment of the present application.

[0040] FIG6 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0041] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 housing; 52 electrode assembly; 53 cover plate; 6 electrical device. DETAILED DESCRIPTION

[0042] Below, some embodiments of the secondary battery and the electrical device 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 identical 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.

[0043] " scope " disclosed in the present application can be 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 the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and any end value can be included or not included independently, and can be arbitrarily combined, that is, 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 parameters, 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 also listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the 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, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on. For example, when a parameter is expressed as an integer selected from "2-10", this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0044] In this application, "a plurality of" or "a plurality of" refers to a number greater than or equal to 2 unless otherwise specified. For example, "one or more" means one or more than or equal to two.

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

[0046] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of such phrases in various locations in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive with other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments. References to "implementations" herein have a similar understanding.

[0047] It will be appreciated by those skilled in the art that, in the methods of various embodiments or examples, the order in which the steps are written does not imply a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible inherent logic. 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 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 steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0048] In this application, in the open technical features or technical solutions described with words such as "contain", "include", and "include", unless otherwise specified, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions that also include additional members in addition to the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or may not include additional members. It can be regarded as providing both the feature or solution of "A consists of a1, a2, and a3" and the feature or solution of "A includes not only a1, a2, and a3, but also other members". In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0049] In this application, the terms "optionally," "optional," and "optional" are optional and refer to either option being present or absent. If a technical solution contains multiple "options," each option is considered independent unless otherwise specified and there are no conflicts or constraints.

[0050] The alkali metal salts in the electrolyte of secondary batteries mainly serve to provide ion conduction. Alkali metal salts can be divided into two major categories: inorganic alkali metal salts and organic alkali metal salts. The content of alkali metal salts in the electrolyte is closely related to the cycle performance of the secondary battery. Alkali metal salts are relatively expensive. Although reducing the content of alkali metal salts in the electrolyte can reduce the cost of the secondary battery, the cycle performance of the secondary battery will be affected. For example, the alkali metal salt in the electrolyte of a lithium-ion battery is a lithium salt. Although reducing the content of lithium salts in the electrolyte can reduce the cost of the lithium-ion battery, the cycle performance of the lithium-ion battery will be affected.

[0051] Based on this, the present application provides a secondary battery comprising an electrolyte and an electrode plate, the electrode plate comprising an electrode active material layer, the electrode active material layer comprising a binder containing alkali metal ions, the amount of alkali metal ions in the binder being A mol (mole), the amount of alkali metal ions in the electrolyte being D mol, and the ratio of A to D being 0.01-1.5. The binder containing alkali metal ions in the above-mentioned secondary battery can replace part of the alkali metal salt, effectively reducing the amount of alkali metal salt used in the electrolyte, thereby effectively reducing the cost of the secondary battery while still ensuring that the secondary battery has excellent cycle performance. A ratio of A to D that is too large or too small will affect the cycle performance of the secondary battery.

[0052] secondary batteries

[0053] One embodiment of the present application provides a secondary battery, comprising an electrolyte and an electrode plate, the electrode plate comprising an electrode active material layer, the electrode active material layer comprising a binder containing alkali metal ions, the amount of alkali metal ions in the binder being A mol, the amount of alkali metal ions in the electrolyte being D mol, and the ratio of A to D being 0.01-1.5.

[0054] In the above embodiment, the ratio of A to D represents the molar ratio of the alkali metal ions in the binder containing alkali metal ions to the alkali metal salt in the electrolyte, that is, the ratio of the alkali metal ions in the binder containing alkali metal ions that can replace the alkali metal salt. The binder containing alkali metal ions in the above embodiment can not only play a binding role, but also serve as a source of alkali metal ions, wherein the alkali metal ions can dissociate in the electrolyte and provide active ions for the secondary battery. Therefore, the binder containing alkali metal ions can replace part of the alkali metal salt, and controlling the ratio of A to D within the above range effectively reduces the amount of alkali metal salt used in the electrolyte, thereby effectively reducing the cost of the secondary battery, while allowing the secondary battery to still have excellent cycle performance. A ratio of A to D that is too large or too small will affect the cycle performance of the secondary battery.

[0055] It should be noted that the alkali metal ions in the binder containing alkali metal ions are the same as the alkali metal ions in the alkali metal salt in the electrolyte, and the above-mentioned secondary battery includes but is not limited to lithium ion batteries, sodium ion batteries or potassium ion batteries. For example: the secondary battery can be a lithium ion battery, the binder containing alkali metal ions can be a binder containing lithium ions, and the alkali metal salt can be a lithium salt; or the secondary battery can be a sodium ion battery, the binder containing alkali metal ions can be a binder containing sodium ions, and the alkali metal salt can be a sodium salt; or the secondary battery can be a potassium ion battery, the binder containing alkali metal ions can be a binder containing potassium ions, and the alkali metal salt can be a potassium salt; or the secondary battery can be a lithium ion battery, the binder containing alkali metal ions can be a binder containing lithium ions and a binder containing sodium ions, and the alkali metal salt can be a lithium salt, and Amol refers to the amount of lithium ions in the binder containing lithium ions. The ratio of A to D in the secondary battery of the present application is always within the range of 0.01-1.5 and will not change with the use state of the secondary battery. Therefore, the ratio of A to D in the used secondary battery can be obtained by disassembling the secondary battery and testing A and D respectively.

[0056] In the present application, the amount of alkali metal ions in the electrolyte, D mol, can be calculated as follows: assuming that the concentration of the alkali metal salt in the electrolyte of the secondary battery is B mol / L and the volume of the electrolyte is CL, then D=B×C.

[0057] In some embodiments, the ratio of A to D is 0.1-1. In this way, the cost of the secondary battery can be further effectively reduced while the secondary battery still has excellent cycle performance.

[0058] In some embodiments, the concentration of the alkali metal salt in the electrolyte is 0.4 mol / L-1.2 mol / L. Controlling the concentration of the alkali metal salt in the electrolyte within a reasonable range can effectively reduce the cost of the secondary battery while still allowing the secondary battery to have excellent cycle performance. It is understood that the concentration of the alkali metal salt in the electrolyte includes but is not limited to: 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L.

[0059] In this application, mol / L means mole per liter.

[0060] In some embodiments, the concentration of the alkali metal salt in the electrolyte is 0.9 mol / L-1.1 mol / L.

[0061] In some embodiments, the mass percentage of the binder containing alkali metal ions is 0.1%-5% based on the mass of the electrode active material layer. Controlling the mass percentage of the binder containing alkali metal ions within the above range can effectively reduce the cost of the secondary battery while taking into account the cycle performance of the secondary battery. It is understood that the mass percentage of the binder containing alkali metal ions includes but is not limited to: 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, and 5%. Furthermore, based on the mass of the electrode active material layer, the mass percentage of the binder containing alkali metal ions is 0.5%-2%.

[0062] In some embodiments, the mass percentage of alkali metal elements in the binder containing alkali metal ions is 3%-8.9% based on the mass of the binder containing alkali metal ions. Controlling the mass percentage of alkali metal elements in the binder containing alkali metal ions within the above range can promote the transmission of alkali metal ions along the molecular chain of the binder, shorten the time it takes for alkali metal ions to be transmitted to the current collector, reduce polarization accumulation, and thus improve the kinetic performance of the secondary battery. It is understood that the mass percentage of alkali metal elements in the binder containing alkali metal ions includes, but is not limited to, 3%, 4%, 5%, 6%, 7%, 8%, and 8.9%.

[0063] In some embodiments, the number average molecular weight of the binder containing alkali metal ions is 3,000-3,000,000. Examples include, but are not limited to, 3,000, 10,000, 50,000, 100,000, 300,000, 500,000, 1,000,000, 1,500,000, 2,000,000, 2,500,000, and 3,000,000. Controlling the number average molecular weight of the binder containing alkali metal ions within the above range can enable the binder containing alkali metal ions to have both good bonding properties and good slurry dispersibility. Furthermore, the number average molecular weight of the binder containing alkali metal ions is 100,000-2,000,000.

[0064] In some embodiments, the binder containing alkali metal ions includes one or more of a binder containing lithium ions, a binder containing sodium ions, and a binder containing potassium ions.

[0065] In some embodiments, the lithium-ion-containing binder includes one or more of lithium polyacrylate (PAALi), lithium alginate, and lithium carboxymethyl cellulose. In the above embodiments, when the lithium-ion-containing binder includes PAALi, PAALi may form an electrolyte film on the surface of the electrode plate, enhancing compatibility with the electrolyte and facilitating lithium ion conduction, thereby improving the fast-charging performance of the secondary battery. This can effectively reduce the cost of the secondary battery while further enhancing its excellent cycling performance.

[0066] In some embodiments, the sodium ion-containing binder includes one or more of sodium polyacrylate (PAANa), sodium alginate, and sodium carboxymethyl cellulose. In the above embodiments, when the lithium ion-containing binder includes PAANa, PAANa can form an electrolyte film on the surface of the electrode plate, enhancing compatibility with the electrolyte and facilitating sodium ion conduction, thereby improving the fast-charging performance of the secondary battery. This can effectively reduce the cost of the secondary battery while further enhancing its excellent cycling performance.

[0067] In some embodiments, the potassium ion-containing binder includes one or more of potassium polyacrylate (PAAK), potassium alginate, and potassium carboxymethyl cellulose. In the above embodiments, when the lithium ion-containing binder includes PAAK, PAAK can form an electrolyte film on the surface of the electrode plate, enhance compatibility with the electrolyte, and assist potassium ion conduction, thereby improving the fast charging performance of the secondary battery. As a result, while effectively reducing battery costs, the secondary battery can further have excellent cycle performance.

[0068] In some embodiments, the electrolyte includes a film-forming additive, and the mass percentage of the film-forming additive is 0.005%-5% based on the mass of the electrolyte. Controlling the mass percentage of the film-forming additive within the above range helps to better form a solid electrolyte interface film on the surface of the electrode plate, reduce the corrosion of the electrolyte on the electrode plate, and thus further improve the cycle performance of the secondary battery. It is understandable that, based on the mass of the electrolyte, the mass percentage of the film-forming additive includes but is not limited to: 0.005%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%. Further, based on the mass of the electrolyte, the mass percentage of the film-forming additive is 0.005%-3%.

[0069] In some embodiments, the film-forming additive includes one or more of an unsaturated ester additive, a sulfur-containing organic additive, and an inorganic compound additive.

[0070] In some embodiments, the unsaturated ester additive includes one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0071] In some embodiments, the sulfur-containing organic additive includes one or more of ethylene sulfite (ES) and propylene sulfite (PS).

[0072] In some embodiments, the inorganic compound additive includes one or more of SO2, CO2, Na2CO3, Na2SO3, K2CO3 and Li2CO3.

[0073] In some embodiments, the electrode active material layer may optionally include other binders. Other binders may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0074] In some embodiments, the alkali metal salt includes one or more of a lithium salt, a sodium salt, and a potassium salt.

[0075] In some embodiments, the lithium salt includes one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorodioxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0076] In some embodiments, the sodium salt includes one or more of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonyl imide (NaFSI), sodium bistrifluoromethanesulfonyl imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorophosphate (NaPO2F2), sodium difluorooxalatoborate (NaDFOB), sodium dioxalatoborate (NaBOB), sodium difluorodioxalatophosphate (NaDFOP) and sodium tetrafluorooxalatophosphate (NaTFOP).

[0077] In some embodiments, the potassium salt includes one or more of potassium hexafluorophosphate (KPF6), potassium tetrafluoroborate (KBF4), potassium perchlorate (KClO4), potassium hexafluoroarsenate (KAsF6), potassium bisfluorosulfonyl imide (KFSI), potassium bistrifluoromethanesulfonyl imide (KTFSI), potassium trifluoromethanesulfonate (KTFS), potassium difluorophosphate (KPO2F2), potassium difluorooxalatoborate (KDFOB), potassium bisoxalatoborate (KBOB), potassium difluorobisoxalatophosphate (KDFOP) and potassium tetrafluorooxalatophosphate (KTFOP).

[0078] In some embodiments, the electrode active material layer further includes an electrode active material and a conductive agent, and the electrode active material includes a positive electrode active material or a negative electrode active material. Since the binder containing alkali metal ions can be used as a binder in both the negative electrode sheet and the positive electrode sheet, the electrode active material can be either a negative electrode active material or a positive electrode active material. Accordingly, the electrode sheet can be either a negative electrode sheet or a positive electrode sheet.

[0079] In some embodiments, the electrode pad is a negative electrode pad.

[0080] In some embodiments, the conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0081] In some embodiments, the solvent may include ethylene carbonate (EC, ), propylene carbonate (PC, ), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate One or more of fluoroethylene carbonate (FEC), 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.

[0082] Another embodiment of the present application provides an electrical device including the above-mentioned secondary battery.

[0083] In addition, the secondary battery and the electric device of the present application will be described below with reference to the drawings as appropriate.

[0084] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0085] Positive electrode

[0086] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material.

[0087] As a non-limiting example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0088] 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 layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0089] It is understandable that the battery will be accompanied by lithium (Li) deintercalation and consumption during the charge and discharge process, and the content of Li in the positive electrode plate is different when the battery is discharged to different states. In the list of positive electrode materials in this application, unless otherwise specified, the Li content is the initial state of the material. The positive electrode material is applied to the positive electrode plate in the battery system, and after the charge and discharge cycle, the Li content in the positive electrode material contained in the plate will usually change. Among them, the Li content can be measured by molar content, but is not limited to this. Regarding "the Li content is the initial state of the material", the initial state of the material refers to the state before the material is added to the positive electrode slurry. It is understandable that new materials obtained by appropriate modification on the basis of the listed positive electrode materials are also within the scope of positive electrode materials. The aforementioned appropriate modification refers to acceptable modification methods for positive electrode materials, and non-limiting examples include coating modification.

[0090] In the examples of positive electrode materials in this application, the oxygen (O) content is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual O content will fluctuate. The O content can be measured by molar content, but is not limited to this.

[0091] In some embodiments, the positive electrode active material may be a positive electrode active material for a battery that is well known in the art. As a non-limiting example, the positive electrode active material may include one or more of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials 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, one or more of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Non-limiting examples of olivine-structured lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.8 Co 0.15 Al 0.05 O2.

[0092] The positive electrode active material includes a sodium ion active material.

[0093] As non-limiting examples, the sodium ion active material may include one or more of the following materials: sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventionally known materials that can be used as sodium ion battery positive electrode active materials may also be used.

[0094] As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Non-limiting examples of sodium transition metal oxides may be Na x MO2, wherein M may include one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0<x≤1.

[0095] As an optional technical solution of the present application, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. Transition metals may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y may be one or more of P, S, and Si; n represents (YO4) n- valence.

[0096] Polyanionic compounds can also be sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds containing anion units and halogen anions. Transition metals may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y may be one or more of P, S, and Si, and n represents (YO4) n- valence state; the halogen can be one or more of F, Cl and Br.

[0097] Polyanionic compounds can also be sodium ions, tetrahedral (YO4) n- Anion unit, polyhedron unit (ZO y ) m+ and an optional halogen anion. Y can be one or more of P, S and Si, and n represents (YO4) n- valence state; Z represents a transition metal, which may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, and m represents (ZO y ) m+ valence state; the halogen can be one or more of F, Cl and Br.

[0098] Polyanionic compounds may include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F and Na3(VO y )2(PO4)2F 3-2y (0≤y≤1) wherein M′ in NaM′PO4F may include one or more of V, Fe, Mn and Ni.

[0099] Prussian blue compounds can be sodium ions, transition metal ions and cyanide ions (CN - ). The transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Non-limiting examples of Prussian blue compounds may include Na a Me b Me' c (CN)6, wherein Me and Me' can each independently be one or more of Ni, Cu, Fe, Mn, Co and Zn, 0<a≤2, 0<b<1, 0<c<1.

[0100] The positive electrode active material includes a potassium ion active material.

[0101] As non-limiting examples, the potassium ion active material may include one or more of the following materials: potassium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for potassium ion batteries may also be used.

[0102] 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 conductive agent, the binder and any other components, are dispersed in a solvent to form a positive electrode slurry; the positive electrode slurry is coated on at least one side of the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained. The type of solvent can be selected from but not limited to any one of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The solid content of the positive electrode slurry can be 40wt%-80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000mPa·s-25000mPa·s. The compacted density of the positive electrode sheet can be 3.0g / cm 3 -3.6g / cm 3, optional 3.3g / cm 3 -3.5g / cm 3 .

[0103] In this application, wt% means mass percentage, mPa·s means millipascal·second, g / cm 3 Indicates grams per cubic centimeter.

[0104] Negative electrode

[0105] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0106] As a non-limiting example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0107] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0108] In some of these embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As a non-limiting example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. Silicon-based materials may include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more 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.

[0109] In some embodiments, the negative electrode active material layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0110] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode collector coated with the negative electrode slurry can be a single surface of the negative electrode collector or two surfaces of the negative electrode collector. The solid content of the negative electrode slurry can be 40wt%-60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa·s-10000mPa·s. The compaction density of the negative electrode sheet can be 1.0g / cm 3 -1.8g / cm 3 .

[0111] electrolytes

[0112] The electrolyte used is the electrolyte mentioned above in this application.

[0113] Isolation film

[0114] In some embodiments, the secondary battery 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.

[0115] In some embodiments, the material of the separator may include one or more 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.

[0116] In some embodiments, the thickness of the isolation film is 6 μm-40 μm, and optionally 12 μm-20 μm.

[0117] In this application, μm means micrometer.

[0118] 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.

[0119] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0120] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery can also be a soft shell, such as a pouch-type soft shell. The material of the soft shell can be plastic. Further, non-limiting examples of plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0121] A secondary battery includes at least one battery cell. A secondary battery may include one or more battery cells.

[0122] In this application, unless otherwise specified, a "battery cell" refers to a basic unit that can achieve the mutual conversion of chemical energy and electrical energy. Further, generally speaking, it includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During the battery's charge and discharge process, active ions are embedded in and out of the positive and negative electrode plates. The electrolyte plays the role of conducting active ions between the positive and negative electrode plates.

[0123] The present application has no particular limitation on the shape of the battery cell, which can be cylindrical, square, or any other shape. For example, FIG1 shows a battery cell 5 with a square structure as an example.

[0124] In some embodiments, referring to Figure 2, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 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 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to actual needs.

[0125] The secondary battery may be a battery module 4 or a battery pack 1 .

[0126] A battery module includes at least one battery cell. The number of battery cells contained in a battery module can be one or more, and those skilled in the art can select an appropriate number based on the application and capacity of the battery module.

[0127] FIG3 shows an example battery module 4. Referring to FIG3 , within the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

[0128] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0129] In some embodiments, the battery modules may be assembled into a battery pack. The battery pack may contain one or more battery modules. Those skilled in the art may select an appropriate number based on the application and capacity of the battery pack.

[0130] Figures 4 and 5 illustrate an example battery pack 1. Referring to Figures 4 and 5 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be placed over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0131] In addition, the present application also provides an electrical device, which includes the secondary battery provided in the present application. The secondary battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can include, but is not limited to, mobile devices, electric vehicles, electric trains, ships, satellites, energy storage systems, etc. Among them, mobile devices can be, for example, mobile phones, laptops, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to these.

[0132] As an electrical device, a secondary battery can be selected according to its usage requirements.

[0133] Figure 6 shows an example of an electric device 6. The electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or battery module can be used.

[0134] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0135] Below, the embodiment of the present application is described. The embodiment described below is exemplary, is only used to explain the present application, and is not to be construed as limiting the present application. Where the technology or conditions are not specified in the embodiment, the technology or conditions described in the literature in this area or the product instructions are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0136] Example 1

[0137] Preparation of negative electrode sheet

[0138] With a solid content of 53%, graphite, sodium carboxymethyl cellulose CMC-Na, conductive carbon SP, binder SBR and binder lithium polyacrylate PAALi were stirred uniformly in water at a high speed according to the ratio of 96:1:0.5:1:1.5. The obtained slurry was controlled to have a weight of 0.209g / 1540.25mm 2 (where g represents grams, mm 2 The slurry on the copper foil is evenly coated on both sides of the 10μm thick copper foil. After the slurry on the copper foil is fully dried in an environment of 50℃-140℃ (where ℃ means Celsius), the density is controlled to be 1.7g / cm 3 Cold pressing is performed to obtain a negative electrode sheet with a thickness of 0.1694 mm (millimeter), which is then cut into pieces with a width of 97 mm for standby use.

[0139] 2) Preparation of positive electrode sheet

[0140] With a solid content of 62%, lithium iron phosphate LFP, binder PVDF and conductive carbon SP are stirred uniformly in a NMP solution at a ratio of 97:2:1. The weight of the obtained slurry is controlled to 0.45g / 1540.25mm 2 Evenly coat the slurry on both sides of a 15μm thick aluminum foil. After the slurry on the aluminum foil is fully dried in an environment of 50℃-140℃, control the density to 2.6g / cm 3 Cold pressing is performed to obtain a positive electrode sheet with a thickness of 0.2384 mm, which is then cut into pieces with a width of 100 mm for standby use.

[0141] 3) Isolation film

[0142] A 12μm thick polypropylene isolation film was selected.

[0143] 4) Battery Preparation

[0144] The 7μm separator was cut into 106mm widths and wound with a 322mm circumference winding needle to create a dry cell. The electrolyte (containing 1% vinylene carbonate (VC), a film-forming additive, 0.85 mol / L LiPF6 as a lithium salt, and a solvent mixture of EC / DMC / PC in a 1:1:1 mass ratio) was then injected to produce a 200Ah lithium-ion battery.

[0145] Examples 2-24 and Comparative Examples 1-3

[0146] The method is basically the same as Example 1, except that the preparation parameters of the negative electrode sheet or the electrolyte are changed, as described in Table 1.

[0147] Example 25

[0148] 1) Preparation of negative electrode sheet

[0149] With a solid content of 53%, hard carbon, polyacrylic acid (PAA), conductive carbon SP, binder SBR and binder sodium polyacrylate (PAANa) were mixed in water at a ratio of 96:1:0.5:1.5:1 and stirred evenly at high speed. The resulting slurry was controlled to have a weight of 0.209g / 1540.25mm 2 Evenly apply it on both sides of a 10μm thick copper foil. After the slurry on the copper foil is fully dried in an environment of 50℃-140℃, control the density to 1.2g / cm 3 Cold pressing is performed to obtain a negative electrode sheet with a thickness of 0.2361 mm, which is then cut into pieces with a width of 97 mm for later use.

[0150] 2) Preparation of positive electrode sheet

[0151] With a solid content of 62%, sodium iron phosphate, binder PVDF and conductive carbon SP were stirred uniformly in a NMP solution at a ratio of 97:2:1. The weight of the obtained slurry was controlled to 0.45g / 1540.25mm 2 Evenly coat the slurry on both sides of a 15μm thick aluminum foil. After the slurry on the aluminum foil is fully dried in an environment of 50℃-140℃, control the density to 2.6g / cm 3 Cold pressing is performed to obtain a positive electrode sheet with a thickness of 0.2384 mm, which is then cut into pieces with a width of 100 mm for standby use.

[0152] 3) Isolation film

[0153] A 12μm thick polypropylene isolation film was selected.

[0154] 4) Battery Preparation

[0155] The 7μm separator was cut into 106mm widths and wound with a 322mm circumference winding needle to create a dry cell. The electrolyte (containing 1% vinylene carbonate (VC), a film-forming additive, 0.85 mol / L NaPF6 sodium salt, and a solvent mixture of EC / DMC / PC in a 1:1:1 mass ratio) was then injected to produce a 200Ah sodium-ion battery.

[0156] Examples 26-27 and Comparative Examples 4-6

[0157] Basically the same as Example 25, except that: the preparation parameters of the negative electrode sheet or the electrolyte are changed, as described in Table 1.

[0158] Material and performance testing

[0159] (1) Test of the amount of alkali metal ions in binders containing alkali metal ions

[0160] The mass of the alkali metal elements in the electrode plate can be tested by inductively coupled plasma emission spectroscopy (ICP), and the amount of alkali metal ions in the binder containing alkali metal ions can be calculated based on the molar mass of the alkali metal elements.

[0161] (2) Test method for the amount of alkali metal ions in the electrolyte

[0162] The ICP method can be used to test the mass of the alkali metal element in the electrolyte, and the amount of alkali metal ions in the electrolyte can be calculated based on the molar mass of the alkali metal element.

[0163] (3) Test of mass percentage of alkali metal elements

[0164] Take a certain mass M1 of an alkali metal ion-containing binder sample and use inductively coupled plasma emission spectroscopy (ICP) to test the mass m1 of the alkali metal element. Then, the average mass percentage of the alkali metal element in the alkali metal ion-containing binder w = m1 / M1×100%. The sample to be tested is prepared by the following method: 0.2g of sample is weighed in a beaker, 10mL (milliliter) of concentrated HNO3 solution is added, and the sample is placed on a 180°C hot plate for digestion for 30min (minutes). After the sample is digested for 30min, it is cooled to room temperature and the digestion solution is transferred to a 50mL volumetric flask through a funnel to make up the volume. The test is carried out according to the industry standard USEPA-6010D-2018. The standard test solution is prepared. The standard test solution is the ICP analysis multi-element standard solution of the National Nonferrous Metals Testing Center. The curve concentration points are 0, 0.2, 0.5, 1.0, and 2.0mg / L (milligrams / liter). The standard solution calibration curve is first made by the instrument, the sample mass and volume are input, and the digested solution is tested. The solution beyond the curve range needs to be diluted before testing. Finally, the element characteristic spectrum of atomic emission is used to identify the presence of the element (qualitative analysis), and the content of the element is determined according to the intensity of the spectral line (quantitative analysis).

[0165] (4) Test of the mass percentage of binder containing alkali metal ions

[0166] As described in the test method described in (3), the mass percentage w of the alkali metal element in the binder containing alkali metal ions can be obtained using the ICP method. Similar to the test method described in (3), the electrode active material layer is first scraped off from the current collector (e.g., copper foil). A certain mass of the electrode active material layer M2 is taken and the mass of the alkali metal element therein is measured using the ICP method as m2. Then, based on the mass of the electrode active material layer, the mass percentage of the binder containing alkali metal ions = m2 / w / M2 × 100%.

[0167] (5) Cycle performance test of lithium-ion batteries

[0168] At 25°C, charge the lithium-ion battery to 3.65V (volts) at a rate of 0.5C, then charge at a constant voltage until the current is less than 0.05C, and then discharge it to 2.5V at a rate of 1C. Perform a cycle test in this full-charge-discharge form until the discharge capacity of the lithium-ion battery decays to 80% of the initial capacity, and record the number of cycles at this time.

[0169] (6) Cycling performance test of sodium ion batteries

[0170] At 25°C, the sodium ion battery was charged to 4.5V at a rate of 0.5C, then charged at a constant voltage until the current was less than 0.05C, and then discharged to 3.8V at a rate of 1C. The cycle test was performed in this full charge and discharge form until the discharge capacity of the sodium ion battery decayed to 80% of the initial capacity, and the number of cycles at this time was recorded.

[0171] (7) Fast charging performance test of lithium-ion batteries and sodium-ion batteries

[0172] Using Cu wire as the three electrodes, charge at a 5C charge rate until the anode potential drops to 0mV (millivolts), then jump to low-rate charging, and charge at low rates of 4C, 3C, 2C, and 1C in sequence to obtain the maximum charging capacity map of the battery cell.

[0173] Starting from 0% SOC, perform step charging with the maximum capacity charging map of the battery cell until the battery cell cut-off voltage reaches 3.8V. The time required from 20% SOC to 80% SOC is recorded as the fast charging time of the battery.

[0174] Table 1

[0175] Table 2

[0176] In Table 1, D represents the amount of alkali metal ions in the electrolyte solution, and the unit is mol, where D=B×C.

[0177] As can be seen from Table 1-2, Example 1-24 uses a binder containing lithium ions, the electrolyte uses a lithium salt, and the ratio of A to D is controlled between 0.01 and 1.5; compared with Comparative Example 1-3, the battery of Example 1-24 has better cycle performance, indicating that the binder containing lithium ions in Example 1-24 can not only replace part of the lithium salt and reduce the cost of the battery, but also enable the battery to still have good cycle performance.

[0178] The batteries of Examples 25-27 use a binder containing sodium ions, the electrolyte uses sodium salt, and the ratio of A to D is controlled between 0.01 and 1.5. Compared with Comparative Examples 4-6, the cycle performance of the batteries of Examples 25-27 is better, indicating that the sodium ion-containing binder in Examples 25-27 can not only replace part of the sodium salt to reduce the cost of the battery, but also enable the battery to still have good cycle performance.

[0179] It can be seen from Example 1 and Examples 6-11 that further controlling the ratio of A to D between 0.1 and 1 can make the battery have better cycle performance.

[0180] The above description of the various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced with each other and will not be repeated herein for the sake of brevity.

[0181] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A secondary battery, characterized in that: The invention comprises an electrolyte and an electrode plate, wherein the electrode plate comprises an electrode active material layer, the electrode active material layer comprises a binder containing alkali metal ions, the amount of the alkali metal ions in the binder is A mol, the amount of the alkali metal ions in the electrolyte is D mol, and the ratio of A to D is 0.01-1.

5.

2. The secondary battery according to claim 1, wherein The ratio of A to D is 0.1-1.

3. The secondary battery according to claim 1 or 2, characterized in that The concentration of the alkali metal salt in the electrolyte is 0.4 mol / L-1.2 mol / L.

4. The secondary battery according to any one of claims 1 to 3, characterized in that: Based on the mass of the electrode active material layer, the mass percentage of the binder containing alkali metal ions is 0.1%-5%.

5. The secondary battery according to any one of claims 1 to 4, characterized in that: Based on the mass of the electrode active material layer, the mass percentage of the binder containing alkali metal ions is 0.5%-2%.

6. The secondary battery according to any one of claims 1 to 5, characterized in that: Based on the mass of the binder containing alkali metal ions, the mass percentage of the alkali metal element in the binder containing alkali metal ions is 3%-8.9%.

7. The secondary battery according to any one of claims 1 to 6, characterized in that: The number average molecular weight of the binder containing alkali metal ions is 3,000-3,000,000.

8. The secondary battery according to any one of claims 1 to 7, characterized in that: The number average molecular weight of the binder containing alkali metal ions is 100,000-2,000,000.

9. The secondary battery according to any one of claims 1 to 8, characterized in that: The binder containing alkali metal ions includes one or more of a binder containing lithium ions, a binder containing sodium ions, and a binder containing potassium ions.

10. The secondary battery according to claim 9, wherein The secondary battery has one or more of the following features: (1a) the lithium ion-containing binder comprises one or more of lithium polyacrylate, lithium alginate, and lithium carboxymethyl cellulose; (1b) the sodium ion-containing binder comprises one or more of sodium polyacrylate, sodium alginate and sodium carboxymethyl cellulose; (1c) The potassium ion-containing binder includes one or more of potassium polyacrylate, potassium alginate and potassium carboxymethyl cellulose.

11. The secondary battery according to any one of claims 1 to 10, characterized in that: The electrolyte includes a film-forming additive. Based on the mass of the electrolyte, the mass percentage of the film-forming additive is 0.005%-5%.

12. The secondary battery according to claim 11, wherein The film-forming additives include one or more of unsaturated ester additives, sulfur-containing organic additives and inorganic compound additives.

13. The secondary battery according to claim 12, characterized in that The secondary battery has one or more of the following features: (2a) the unsaturated ester additive comprises one or more of vinylene carbonate and fluoroethylene carbonate; (2b) the sulfur-containing organic additive comprises one or more of ethylene sulfite and propylene sulfite; (2c) The inorganic compound additive includes one or more of SO2, CO2, Na2CO3, Na2SO3, K2CO3 and Li2CO3.

14. The secondary battery according to any one of claims 3 to 13, characterized in that: The alkali metal salt includes one or more of lithium salt, sodium salt and potassium salt.

15. The secondary battery according to claim 14, characterized in that The secondary battery has one or more of the following features: (3a) The lithium salts include lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, One or more of lithium difluorodioxalatophosphate and lithium tetrafluorooxalatophosphate; (3b) the sodium salt includes one or more of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium difluorophosphate, sodium difluorooxalatoborate, sodium dioxalatoborate, sodium difluorodioxalatophosphate and sodium tetrafluorooxalatophosphate; (3c) The potassium salt includes one or more of potassium hexafluorophosphate, potassium tetrafluoroborate, potassium perchlorate, potassium hexafluoroarsenate, potassium bis(fluorosulfonyl)imide, potassium bis(trifluoromethanesulfonyl)imide, potassium trifluoromethanesulfonate, potassium difluorophosphate, potassium difluorooxalatoborate, potassium dioxalatoborate, potassium difluorodioxalatophosphate and potassium tetrafluorooxalatophosphate.

16. The secondary battery according to any one of claims 1 to 15, characterized in that: The electrode active material layer further includes an electrode active material and a conductive agent, and the electrode active material includes a positive electrode active material or a negative electrode active material.

17. An electrical device, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 16.

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