Battery, terminal apparatus, and battery manufacturing method

Abstract

A battery, comprising a negative pole piece and a separator. The negative pole piece comprises a negative electrode active material layer and a functional layer arranged in a stacked manner, the functional layer comprising Mg2+, and a portion of the Mg2+ being embedded in the negative electrode active material layer. The separator comprises a base film, and a coating layer disposed on the surface of the base film, the coating layer being bonded to the base film and the functional layer. The coating layer comprises a polymer material, and the polymer material is coordination cross-linked with at least a portion of the remaining Mg2+ in the functional layer. The polymer material in the coating layer and the Mg2+ in the functional layer are used to perform a coordination cross-linking reaction, so as to effectively improve the bonding strength between the negative pole piece and the separator, which helps to prevent the battery from deforming during a cycle process. In addition, after the polymer material is ionized, the ion performance of the polymer material can be effectively improved, the internal resistance of the battery is reduced, and quick charging performance of the battery is improved. The invention further provides a terminal apparatus comprising said battery, and a manufacturing method for said battery.

Description

Battery, terminal device, and battery manufacturing method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is filed with the China Patent Office on August 17, 2023, with application number 202311035539.6 and application name “Battery, terminal device and battery manufacturing method”, all contents of which are incorporated by reference in this application. Technical Field

[0003] The present application relates to the field of batteries, and in particular to a battery, a terminal device, and a method for manufacturing a battery. Background Art

[0004] Batteries are a crucial component of terminal devices. As users demand thinner, lighter, and longer-lasting devices, they are placing increasing demands on battery energy density and safety. During the initial charge, a SEI film forms on the negative electrode of a battery. This formation consumes a significant amount of active lithium, which no longer participates in the electrochemical cycle, resulting in a decrease in the actual amount of active lithium. This leads to low initial efficiency of the negative electrode, and consequently, a decrease in the battery's energy density.

[0005] Summary of the Invention

[0006] In a first aspect, the present application provides a battery comprising a negative electrode plate and a separator. The negative electrode plate comprises a stacked negative electrode active material layer and a functional layer, wherein the functional layer comprises Mg 2+ , part of Mg 2+ Embedded in the negative electrode active material layer; the diaphragm includes a base film and a coating layer located on the surface of the base film, the coating layer is bonded to the base film and the functional layer. The coating layer includes a polymer material, the polymer material and the remaining at least part of the Mg in the functional layer 2+ Coordination cross-linking.

[0007] In the above design, a functional layer is set in the negative electrode to improve the initial efficiency of the negative electrode; the polymer material itself has bonding properties and can play a certain bonding role; in addition, the polymer material in the coating layer and the Mg in the functional layer are used to improve the initial efficiency of the negative electrode. 2+ A coordination cross-linking reaction occurs to effectively improve the bonding strength between the negative electrode and the separator, which helps prevent the battery from deforming during the cycle. In addition, after the polymer material is ionized, it can effectively improve the ion conductivity of the polymer material, reduce the internal resistance of the battery, and help improve the fast charging performance of the battery.

[0008] In some possible embodiments of the present application, the general structural formula of the polymer material is:

[0009] Among them, R1 is used to 2+Coordination cross-linking, n>0, m≥0.

[0010] In the above design, R1 has bonding properties on one hand and Mg 2+ A coordination cross-linking reaction occurs, thereby causing the functional layer and the polymer material to cross-link with each other, thereby improving the bonding strength between the functional layer and the polymer material.

[0011] In some possible embodiments of the present application, R1 includes at least one of a carboxyl group, an amide group, an aromatic acid group, and a sulfonate group.

[0012] In the above design, carboxyl, amide, aromatic acid and sulfonate groups can all react with Mg 2+ Coordination cross-linking reaction occurs.

[0013] In some possible embodiments of the present application, R2 is at least one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a nitro group, an alcohol group, an amino group, or a cyano group.

[0014] In the above design, R2 can be selected based on the specific composition of the electrolyte, the specific functional group of R1, etc., to adjust the swelling properties, mechanical properties and processability of the polymer material. In some possible embodiments of the present application, n≥m.

[0015] In the above design, polymer materials are beneficial to R1 and Mg 2+ A coordination cross-linking reaction occurs to further increase the bonding strength between the separator and the negative electrode.

[0016] In some possible implementations of the present application, 10<n<10000, 10<m<10000.

[0017] In the above design, increasing the molecular weight of the polymer material is beneficial to improving the bonding performance of the polymer material.

[0018] In some possible embodiments of the present application, the bonding strength between the negative electrode plate and the separator is greater than 0.5 N / m.

[0019] In a second aspect, the present application further provides a terminal device, which includes a battery.

[0020] In a third aspect, the present application also provides a method for manufacturing a battery, comprising the following steps: providing a negative electrode preform, the negative electrode preform comprising a stacked negative electrode active material layer and a pre-embedded layer, the pre-embedded layer comprising Mg and / or Mg 2+ ; providing a base film, coating a coating layer on the surface of the base film to form a diaphragm together, the coating layer including a polymer material, bonding the coating layer to the pre-embedded layer; assembling a battery preform, the battery preform including a diaphragm and a negative electrode preform; and forming the battery preform, partially Mg and / or partially Mg in the pre-embedded layer2+ Entering the negative electrode active material layer, the polymer material and at least part of the Mg that is not embedded in the pre-embedded layer 2+ and / or Mg formed by oxidation of at least part of the unintercalated Mg 2+ Coordination cross-linking.

[0021] In the above design, a pre-embedded layer is provided in the process of manufacturing the negative electrode plate to improve the initial efficiency of the negative electrode; the polymer material in the coating layer itself has adhesive properties and can play a certain adhesive role; in addition, the pre-embedded layer contains Mg and / or Mg 2+ , Mg can be transformed into Mg 2+ , polymer materials can be combined with Mg 2+ A coordination cross-linking reaction occurs to form a functional layer, thereby effectively improving the peel strength between the negative electrode and the separator, which is beneficial to prevent the battery from deforming during the cycle. In addition, after the polymer material is ionized, the ion conductivity of the polymer material can be effectively improved.

[0022] In some possible embodiments of the present application, the pre-embedded layer includes at least one of a single metal element, a metal alloy, and a metal compound of magnesium.

[0023] In the above design, magnesium-containing materials are used to supplement magnesium to the negative electrode plate.

[0024] In some possible embodiments of the present application, the ion exchange capacity of the polymer material is greater than or equal to 0.2 meq / g.

[0025] In the above design, polymer materials and Mg 2+ It has a high coordination ability, which makes the polymer material and Mg 2+ The coordination cross-linking reaction can fully occur, thereby increasing the bonding strength between the separator and the negative electrode.

[0026] In some possible embodiments of the present application, the general structural formula of the polymer material is:

[0027] Among them, R1 and Mg 2+ Coordination cross-linking, n>0, m≥0.

[0028] In the above design, R1 and Mg 2+ Coordination cross-linking reaction occurs, so that the polymer material and Mg 2+ Cross-linking to improve the bonding strength between the separator and the negative electrode.

[0029] In some possible embodiments of the present application, R1 includes at least one of a carboxyl group, an amide group, an aromatic acid group, and a sulfonate group.

[0030] In the above design, carboxyl, amide, aromatic acid and sulfonate groups can all react with Mg 2+ Coordination cross-linking reaction occurs.

[0031] In some possible embodiments of the present application, R2 is at least one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a nitro group, an alcohol group, an amino group, or a cyano group.

[0032] In the above design, R2 is used to increase the polarity of the polymer material, which is beneficial to improving the bonding performance of the polymer material and also beneficial to improving the affinity between the polymer material and the electrolyte in the battery.

[0033] In some possible implementations of the present application, n≥m.

[0034] In the above design, it is beneficial for R1 and Mg 2+ Coordination cross-linking occurs to further increase the bonding strength between the separator and the negative electrode.

[0035] In some possible implementations of the present application, 10<n<10000, 10<m<10000.

[0036] In the above design, increasing the molecular weight of the polymer material is beneficial to improving the bonding performance of the polymer material. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic cross-sectional view of a battery provided by the related art of this application.

[0038] FIG2 is a schematic structural diagram of a mobile phone terminal device provided in an embodiment of the present application.

[0039] FIG3 is a cross-sectional schematic diagram of an electrode assembly of a wound structure provided in an embodiment of the present application.

[0040] FIG4 is a cross-sectional schematic diagram of an electrode assembly of a laminated structure provided in an embodiment of the present application.

[0041] FIG5 is a schematic cross-sectional view of a partial area of ​​a battery provided in an embodiment of the present application.

[0042] FIG6 is a schematic diagram of the structure of a battery provided in an embodiment of the present application.

[0043] FIG7 is a schematic structural diagram of the negative electrode preform provided in an embodiment of the present application.

[0044] FIG8 is a schematic structural diagram of the negative electrode preform shown in FIG7 after the surface of the negative electrode preform is covered with a separator.

[0045] FIG9 is a schematic diagram showing the structure of a battery obtained after the battery preform is formed.

[0046] Description of main component symbols Terminal device: 200 Battery: 100, 100' Electrode assembly: 110 Negative electrode sheet: 10, 10' Negative electrode current collector: 11, 11' Negative electrode active material layer: 13, 13' Negative electrode active material: 132 Binder: 134 Conductive agent: 136 Functional layer: 15, 15' Pre-embedded layer: 150, 150' Positive electrode sheet: 20, 20' Positive electrode current collector: 21 Positive electrode active material layer: 23 Separator: 30, 30' Base film: 31 Coating layer: 33 Negative electrode preform: 50. DETAILED DESCRIPTION

[0047] In order to more clearly understand the above-mentioned objects, features and advantages of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth to facilitate a full understanding of the present application. The embodiments described are only a part of the embodiments of the present application, rather than all of the embodiments.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes all and any combinations of one or more of the relevant listed items.

[0049] In the various embodiments of the present application, for ease of description and not limitation, the term "connection" used in the patent specification and claims of the present application is not limited to physical or mechanical connections, whether direct or indirect. "Up," "down," "above," "below," "left," "right," etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0050] Please refer to Figure 1. A battery 100' is provided in the related art, including a negative electrode plate 10', a positive electrode plate 20' and a separator 30'. The separator 30' is arranged between the negative electrode plate 10' and the positive electrode plate 20'. The separator 30' can be a polyethylene or polypropylene base film, or polyvinylidene difluoride (PVDF) can be coated on the base film. Before the battery 100' is formed, the negative electrode plate 10' includes a stacked negative electrode current collector 11', a negative electrode active material layer 13' and a functional layer 15'. After the formation, part of the Mg or Mg in the functional layer 15' 2+Embedded into the negative electrode active material layer 13', providing Mg for the negative electrode active material layer 13' 2+ , compensating for some of the irreversible active lithium to improve the initial efficiency of the negative electrode. The residual material between the separator 30' and the negative electrode active material layer 13' has poor interfacial compatibility with the separator 30' and / or the negative electrode active material layer 13', resulting in weak adhesion between the negative electrode sheet 10' and the separator 30', and the battery 100' is prone to deformation during charge and discharge.

[0051] Please refer to Figure 2. The embodiment of the present application provides a terminal device 200 including a battery 100. The battery 100 is an important component of the terminal device 200 such as a mobile phone, a notebook, a camera, and a car. Based on the user's demand for a thin and light battery 100 and long battery life, the requirements for the energy density and cycle performance of the battery 100 are also getting higher and higher. The level of the initial efficiency of the negative electrode determines the performance of the battery 100 to a certain extent. During the first charging process of the battery 100, the electrolyte is reduced and decomposed on the surface of the negative electrode active material to form a solid electrolyte membrane (Solid Electrolyte Interface, referred to as SEI membrane). In the process of forming the SEI membrane, active lithium is consumed, and some active lithium is difficult to deintercalate and form "dead lithium". For certain types of negative electrode active materials, the initial efficiency is low, such as silicon materials, tin materials, etc. The initial efficiency of the battery 100 containing silicon material is about 70%-85%. During the charging and discharging process of the battery 100, the capacity and energy density will be further reduced. The silicon material has small particles and a large specific surface area, and more active lithium will be consumed in the process of forming the SEI film. The silicon material has poor conductivity, resulting in some active lithium being unable to be deintercalated.

[0052] Referring to Figures 3 and 4, the battery 100 provided in an embodiment of the present application includes an electrode assembly 110, an electrolyte (not shown) and a packaging film (not shown), wherein the electrolyte and the electrode assembly 110 are encapsulated in the packaging film. The electrode assembly 110 includes a negative electrode sheet 10, a positive electrode sheet 20 and a separator 30, wherein the separator 30 is located between the positive electrode sheet 20 and the negative electrode sheet 10. The battery 100 can be a wound structure (see Figure 3), that is, the negative electrode sheet 10, the separator 30 and the positive electrode sheet 20 are formed by stacking and winding to form the electrode assembly 110. The battery 100 can also be a laminated structure (see Figure 4), that is, the negative electrode sheet 10, the separator 30 and the positive electrode sheet 20 are formed by stacking in sequence to form the electrode assembly 110.

[0053] Referring to Figure 5 , the negative electrode sheet 10 includes a negative electrode current collector 11, a negative electrode active material layer 13, and a functional layer 15, which are stacked in sequence. The negative electrode active material layer 13 is located on the surface of the negative electrode current collector 11, and the functional layer 15 is located on the surface of the negative electrode active material layer 13 facing away from the negative electrode current collector 11. The functional layer 15 is located between the separator 30 and the negative electrode active material layer 13. The negative electrode current collector 11 can be made of copper foil, nickel foil, or a carbon-based current collector.

[0054] The negative electrode active material layer 13 may include a negative electrode active material 132, a binder 134, and a conductive agent 136. The negative electrode active material 132 may be a silicon material or a tin material. Among them, silicon material has the advantages of high gram capacity, volume specific capacity, suitable lithium insertion potential, low cost, etc. Silicon materials may include but are not limited to elemental silicon, silicon-carbon materials, silicon-oxygen materials, etc. The conductive agent 136 may be graphite, carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes or carbon fibers, etc. The binder 134 may be polyacrylic acid (PAA), styrene, 1,3-butadiene polymer (SBR), polyvinyl alcohol (PVA), etc. The thickness of the negative electrode active material layer 13 may be 20μm-200μm.

[0055] The positive electrode sheet 20 includes a positive electrode current collector 21 and a positive electrode active material layer 23, which are stacked. The positive electrode current collector 21 can be made of aluminum foil or nickel foil. The positive electrode active material layer 23 contains a positive electrode active material, a binder, and a conductive agent. The positive electrode active material includes a compound that reversibly intercalates and deintercalates lithium ions (lithiated intercalation compound). In some embodiments, the positive electrode active material may include a lithium transition metal composite oxide. The lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.

[0056] Referring also to FIG6 , the separator 30 includes a base film 31 and a coating layer 33 disposed on a surface of the base film 31. The base film 31 has a porous structure and can be made of at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene can be selected from at least one of high-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene.

[0057] The functional layer 15 includes Mg 2+ , part of Mg 2+ It is embedded in the negative electrode active material layer 13 to supplement magnesium and the like to the negative electrode plate 10 , thereby compensating for part of the irreversible active lithium, thereby improving the initial efficiency of the battery 100 .

[0058] The coating layer 33 is located between the negative electrode plate 10 and the base film 31. The coating layer 33 includes a polymer material, and the polymer material and at least part of the remaining Mg in the functional layer 15 2+ The coordination cross-linking is used to increase the bonding strength between the negative electrode plate 10 and the separator 30. Therefore, the coating layer 33 can reduce the risk of poor interface due to the reduced bonding strength between the negative electrode plate 10 and the separator 30 after the functional layer 15 is provided.

[0059] The general structural formula of polymer materials can be:

[0060] m and n are both integers, n>0, m≥0. When m=0, the general structural formula of the polymer material can be:

[0061] Among them, R1 can be at least one of carboxyl (-COOH), amide (-CONH2), aromatic acid radical (-phCOOH) and sulfonic acid radical (-SO3H). On the one hand, R1 has bonding properties; on the other hand, R1 can bind to Mg 2+ A coordination cross-linking reaction occurs, so that the polymer material and the functional layer 15 are connected through chemical bonds, thereby increasing the bonding strength between the separator 30 and the negative electrode plate 10 .

[0062] R2 can be at least one of hydrogen, an alkyl group with 1-6 carbon atoms, a nitro group (-NO2), an alcohol group (-OH), an amino group (-NH2), or a cyano group (-CN). R2 can be selected based on the specific composition of the electrolyte and the specific functional group of R1 to adjust the swelling properties, mechanical properties, and processability of the polymer material. For example, functional groups such as -NO2, -OH, -NH2, or -CN can improve the polarity of the polymer material, thereby improving its swelling properties in the electrolyte; groups such as hydrogen and an alkyl group with 1-6 carbon atoms can reduce the brittleness of the polymer material, facilitating its processing.

[0063] In some embodiments, n≥m, which means that the number of R1 is greater than or equal to the number of R2, which is beneficial for more R1 and Mg 2+ A coordination cross-linking reaction occurs to increase the bonding strength between the separator 30 and the negative electrode sheet 10 .

[0064] In some embodiments, 10<n<10000, 10<m<10000, the molecular weight of the polymer material can be 1000-3000000, and increasing the molecular weight of the polymer material is beneficial to improving the bonding performance of the polymer material.

[0065] In some embodiments, when m=0, the polymer material may be polyacrylamide (PAM), poly(sodium 4-styrenesulfonate), or PSS. The structural formula of PAM is The structural formula of PSS is

[0066] When m>0, the polymer material can be a copolymer, which can be formed by random copolymerization or block copolymerization. For example, taking block copolymerization as an example, the polymer material can be a copolymer of PAA and polyethylene (PE), a copolymer of PAM and polymethyl methacrylate (PMMA), or a copolymer of PAA and PMMA. Among them, the structural formula of the copolymer of PAA and PE is The structural formula of the copolymer of PAM and PMMA is The structural formula of the copolymer of PAA and PMMA is wait.

[0067] In some embodiments, the coating layer 33 may further include ceramic materials, such as alumina, boehmite, etc. The ceramic materials are dispersed in the polymer material. The ceramic materials can reduce the thermal shrinkage of the coating layer 33 to improve the safety of the battery 100.

[0068] In some embodiments, the coating layer 33 may also be located on the side of the separator 30 facing the positive electrode sheet 20 to bond the separator 30 and the positive electrode sheet 20 .

[0069] In some embodiments, the coating layer 33 may have a thickness of 0.5 μm-6 μm, specifically 1 μm, 2.5 μm, 3 μm, 4.5 μm, etc.

[0070] In some embodiments, the surface density of the coating layer 33 is 0.15 g / m 2 -0.8g / m 2 .

[0071] Referring to FIG. 7 to FIG. 9 , some embodiments of the present application further provide a method for manufacturing a battery 100 , which may include the following steps:

[0072] Step S1 : Referring to FIG. 7 , a negative electrode preform 50 is provided. The negative electrode preform 50 includes a negative electrode active material layer 13 and a pre-embedded layer 150 that are stacked.

[0073] The negative electrode preform 50 may further include a negative electrode current collector 11 , a negative electrode active material layer 13 disposed on a surface of the negative electrode current collector 11 , and a pre-embedded layer 150 located on a surface of the negative electrode active material layer 13 facing away from the negative electrode current collector 11 .

[0074] The pre-embedded layer 150 is used to supplement magnesium. The material of the pre-embedded layer 150 can be a single metal, a metal alloy, and / or a metal compound. For example, the material of the pre-embedded layer 150 can be at least one of metal magnesium, magnesium-aluminum alloy, magnesium-zinc alloy, magnesium-tin alloy, magnesium-manganese alloy, magnesium chloride, and magnesium silicate.

[0075] Methods for providing the pre-embedded layer 150 on the surface of the negative electrode active material layer 13 include, but are not limited to, roll pressing, electroplating, vapor deposition, magnesium thermal method, etc. For example, in some embodiments, when manufacturing the negative electrode sheet 10, the binder 134 can be first dissolved in a solvent, and the negative electrode active material 132 and the conductive agent 136 can be dispersed in the solvent and fully stirred to form a negative electrode slurry. The negative electrode slurry is then coated on the negative electrode current collector 11 and dried to remove the solvent. The negative electrode active material 132 and the conductive agent 136 are bonded by the binder 134 to form the negative electrode active material layer 13. The negative electrode active material layer 13 is bonded to the negative electrode current collector 11 by the binder 134. The pre-embedded layer 150 is then rolled on the surface of the negative electrode active material layer 13 facing away from the negative electrode current collector 11 and sintered at a low temperature (e.g., less than 200°C) to form the negative electrode sheet 10. In some embodiments, the pre-embedding layer 150 may also be formed on the surface of the negative electrode active material layer 13 by electroplating. For example, when the pre-embedding layer 150 is used to supplement magnesium, a molten salt of MgCl2 may be electrolytically plated onto the surface of the negative electrode active material layer 13. In some embodiments, magnesium vapor may be vapor-deposited in a suspended state in a reactor onto the surface of the negative electrode active material layer 13. In some embodiments, the pre-embedding layer 150 is coated on the surface of the negative electrode active material layer 13 and heated at a low temperature so that a portion of the pre-embedding layer 150 penetrates into the negative electrode active material layer 13.

[0076] Step S2 : Referring to FIG. 8 , a base film 31 is provided, a coating layer 33 is coated on the surface of the base film 31 to form the diaphragm 30 , and the coating layer 33 is bonded to the pre-embedded layer 150 .

[0077] The coating layer 33 can be coated on one surface of the base film 31 or on two opposite surfaces of the base film 31. When the coating layer 33 is coated on only one surface of the base film 31, the coating layer 33 is located on the side of the base film 31 facing the negative electrode 10.

[0078] Step S3 : Assemble a battery preform (not shown) in combination with FIG. 9 . The battery preform includes a separator 30 and a negative electrode preform 50 .

[0079] The battery preform further includes a positive electrode sheet, an electrolyte, etc. The negative electrode sheet 10 and the positive electrode sheet are located on opposite sides of the separator 30 , and the electrolyte infiltrates the negative electrode sheet 10 , the positive electrode sheet and the separator 30 .

[0080] Step S4: Please refer to FIG9 , the battery preform is formed, and part of the Mg and / or part of the Mg in the pre-embedded layer 150 is formed. 2+ Entering the negative electrode active material layer 13, the polymer material and at least part of the Mg that is not embedded in the pre-embedded layer 150 2+ and / or Mg formed by oxidation of at least part of the unintercalated Mg 2+ The coordination and cross-linking are carried out to form the battery 100 .

[0081] During the battery 100 formation process, Mg 2+ The coordination cross-linking reaction occurs with R1 in the polymer material, or the Mg in the pre-embedded layer 150 is converted into Mg during the chemical formation process. 2+ After that, it undergoes coordination cross-linking reaction with R1 in the polymer material, so that the separator 30 and the negative electrode plate 10 can be connected to each other through chemical bonds; in addition, the polymer material also has an adhesive effect, which bonds the separator 30 and the negative electrode plate 10, which is beneficial to improve the interface stability of the negative electrode plate 10 during the cycle of the battery 100; furthermore, the polymer material and Mg 2+ The coordination cross-linking reaction occurs, that is, the polymer material is ionized, which can effectively improve the ion conductivity of the polymer material and have better lithium ion transmission kinetics, thereby reducing the internal resistance of the battery 100, which is beneficial to improving the fast charging performance of the battery 100.

[0082] In some embodiments, in Mg or Mg 2+ During the embedding process of the negative electrode active material layer 13, by-products such as magnesium carbonate and lithium silicate are generated and loaded on the surface of the negative electrode active material layer 13. The polymer material can also bind the by-products and react with the Mg in the by-products. 2+ Coordination cross-linking.

[0083] The ion exchange capacity (IEC) of the polymer material is greater than or equal to 0.2 meq / g, so that the polymer material and Mg 2+ It has a high coordination ability, so that the polymer material and the Mg provided by the pre-embedded layer 150 2+ The coordination cross-linking reaction occurs fully.

[0084] The following describes the implementation of the present application through specific examples and comparative examples.

[0085] Comparative Example 1

[0086] The negative electrode sheet 10 contains silicon oxide as the negative electrode active material, with the mass fraction of the negative electrode active material in the negative electrode active material layer 13 being 10%. The binder 134 is PAA. No pre-embedded layer 150 is provided. A coating layer 33 is provided on the surface of the separator 30 facing the negative electrode sheet 10. The polymer material in the coating layer 33 is PVDF.

[0087] Comparative Example 2

[0088] The difference from Comparative Example 1 is that a pre-embedded layer 150 is provided in Comparative Example 2. The material of the pre-embedded layer 150 is metal magnesium, and the thickness of the pre-embedded layer 150 is 3 μm.

[0089] Example 1

[0090] The difference from Comparative Example 1 is that: in Example 1, a pre-embedded layer 150 is provided, the material of the pre-embedded layer 150 is metallic magnesium, and the thickness of the pre-embedded layer 150 is 3 μm; the polymer material in the coating layer 33 is a copolymer of PAA and PE.

[0091] Example 2

[0092] The negative electrode sheet 10 uses silicon oxide as the negative electrode active material, accounting for 40% by mass of the negative electrode active material layer 13. The binder 134 is composed of PAA and SBR. The pre-embedding layer 150 is made of metallic magnesium and has a thickness of 5 μm. The surface of the separator 30 facing the negative electrode sheet 10 is provided with a coating layer 33, which is a copolymer of PAM and PMMA.

[0093] Example 3

[0094] The negative electrode sheet 10 contains silicon oxide as the negative electrode active material, with the mass fraction of the negative electrode active material in the negative electrode active material layer 13 being 10%. The binder 134 is SBR. The pre-embedding layer 150 is made of metallic magnesium and has a thickness of 5 μm. The surface of the separator 30 facing the negative electrode sheet 10 is provided with a coating layer 33, which is a polymer material made of PAM.

[0095] Example 4

[0096] The negative electrode sheet 10 uses silicon carbide as the negative electrode active material, accounting for 5% by mass of the negative electrode active material layer 13. The binder 134 is PVA. The pre-embedding layer 150 is made of metallic magnesium and has a thickness of 2 μm. The surface of the separator 30 facing the negative electrode sheet 10 is provided with a coating layer 33, which is a copolymer of PAA and PMMA.

[0097] Example 5

[0098] The negative electrode sheet 10 uses silicon carbide as the negative electrode active material, accounting for 10% by mass of the negative electrode active material layer 13. The binder 134 is composed of PAA and SBR. The pre-embedding layer 150 is made of metallic magnesium and has a thickness of 3 μm. The surface of the separator 30 facing the negative electrode sheet 10 is provided with a coating layer 33, which is made of a polymer material called PSS.

[0099] The initial negative electrode efficiency and peel strength of each example and comparative example were tested, and the results are recorded in Table 1. The initial negative electrode efficiency test procedure included assembling the negative electrode sheets, separators, and lithium sheets from Comparative Examples 1-2 and Examples 1-5 into half-cells, and measuring the discharge and charge capacities of the half-cells during the first cycle. The ratio of the discharge capacity to the charge capacity was the initial negative electrode efficiency. The discharge rates during testing were 0.04C, 0.02C, and 0.01C, respectively; the charge rate was 0.04C; and the voltage ranged from 0V to 2V. The peel strength test procedure between the negative electrode sheet 10 and separator 30 included removing the negative electrode sheets 10 and separator 30 from the formed batteries 100 of Comparative Examples 1-2 and Examples 1-5, rolling them three times with a 1kg roller, and then testing them using a 180° tensile tester. Please refer to Table 1 for the different conditions and corresponding test results for Comparative Examples 1-2 and Examples 1-5.

[0100] Table 1

[0101] From the test results in Table 1, it can be seen that in Comparative Example 1, the pre-embedded layer 150 is not provided, that is, the battery 100 is not supplemented with magnesium, and the initial efficiency of the negative electrode sheet is low. In Comparative Example 2, the pre-embedded layer 150 is provided, and the initial efficiency of the negative electrode sheet is improved to a certain extent compared with Comparative Example 2; however, in Comparative Example 2, the pre-embedded layer 150 is bonded to the separator 30 by PVDF, and PVDF will not react with Mg. 2+ The PVDF and the unembedded pre-embedded layer 150 undergo a coordination cross-linking reaction and are connected by chemical bonds. Therefore, the bonding performance between the negative electrode plate and the separator is low. In Examples 1-5, a pre-embedded layer 150 is provided to supplement magnesium to the negative electrode plate 10 to improve the initial efficiency of the negative electrode plate. In addition, a polymer material capable of undergoing a coordination cross-linking reaction with the pre-embedded layer 150 is provided between the pre-embedded layer 150 and the separator 30, so that the polymer material and Mg 2+ After coordination and cross-linking, the two electrodes are connected to each other through chemical bonds, thereby effectively improving the peel strength between the negative electrode sheet 10 and the separator 30 .

[0102] In some embodiments, under the same conditions, negative electrode sheets without and with magnesium supplementation were assembled into full batteries 100 for testing, wherein the coating layer 33 was not provided. The discharge rates during testing were 0.04C, 0.02C, and 0.01C, respectively, and the charge rate was 0.04C. The voltage range was 3V-4.5V, and the test results are shown in Table 2. The test results show that the initial efficiency of the battery 100 after magnesium supplementation was significantly improved compared to the initial efficiency of the battery 100 without magnesium supplementation.

[0103] Table 2

[0104] In some embodiments, under identical conditions, separators 30 containing magnesium supplementation but no coating layer 33 and separators containing magnesium supplementation and a coating layer 33 were assembled into full batteries 100 and tested at discharge rates of 0.04C, 0.02C, and 0.01C, respectively, and at a charge rate of 0.04C, with a voltage range of 3V to 4.5V. The test results are shown in Table 3. The test results demonstrate that the cycle life of the battery 100 containing magnesium supplementation and a coating layer 33 is significantly improved compared to the battery 100 containing magnesium supplementation but no coating layer 33.

[0105] Table 3

[0106] In the embodiment of the present application, a pre-embedded layer 150 is provided during the production of the negative electrode sheet 10 to improve the initial efficiency of the negative electrode; and a coating layer 33 is provided between the pre-embedded layer 150 and the separator 30. The polymer material in the coating layer 33 has adhesive properties and can play a certain adhesive role. In addition, the pre-embedded layer 150 contains Mg and / or Mg 2+ , Mg can be transformed into Mg 2+ , polymer materials can be combined with Mg 2+ After the coordination cross-linking reaction occurs, they are connected to each other through chemical bonds, thereby effectively improving the peel strength between the negative electrode plate 10 and the separator 30, which is beneficial to prevent the battery 100 from deforming during the cycle. In addition, after the polymer material is ionized, the ion conductivity of the polymer material can be effectively improved.

[0107] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present application should not depart from the spirit and scope of the technical solutions of the present application.

Claims

1. A battery, characterized in that: include: The negative electrode sheet comprises a negative electrode active material layer and a functional layer stacked together, wherein the functional layer comprises Mg 2+ , part of the Mg 2+ embedded in the negative electrode active material layer; as well as A diaphragm, comprising a base film and a coating layer located on a surface of the base film, wherein the coating layer bonds the base film and the functional layer; Wherein, the coating layer includes a polymer material, and the polymer material and the remaining at least part of the Mg in the functional layer 2+ Coordination cross-linking.

2. The battery according to claim 1, characterized in that The general structural formula of the polymer material is: Wherein, the R1 is used to 2+ Coordination cross-linking, n>0, m≥0.

3. The battery according to claim 2, characterized in that The R1 includes at least one of a carboxyl group, an amide group, an aromatic acid group and a sulfonate group.

4. The battery according to claim 2 or 3, characterized in that: The R2 is at least one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a nitro group, an alcohol group, an amino group or a cyano group.

5. The battery according to claim 2 or 3, characterized in that: n≥m.

6. The battery according to claim 2 or 3, characterized in that: 10<n<10000, 10<m<10000.

7. The battery according to claim 1, characterized in that The bonding strength between the negative electrode plate and the separator is greater than 0.5 N / m.

8. A terminal device, characterized in that: A battery comprising any one of claims 1 to 7.

9. A method for manufacturing a battery, characterized in that: The following steps are involved: A negative electrode preform is provided, wherein the negative electrode preform comprises a stacked negative electrode active material layer and a pre-embedded layer, wherein the pre-embedded layer comprises Mg and / or Mg 2+ ; Providing a base film, coating a coating layer on the surface of the base film to form a diaphragm together, wherein the coating layer includes a polymer material, and bonding the coating layer to the pre-embedded layer; Assembling a battery preform, wherein the battery preform includes the separator and the negative electrode preform; as well as The battery preform is formed, and part of the Mg and / or part of the Mg in the pre-embedded layer 2+ Entering the negative electrode active material layer, the polymer material and the Mg 2+ and / or Mg formed after oxidation of at least part of the Mg that is not embedded 2+ Coordination cross-linking.

10. The method for manufacturing a battery according to claim 9, characterized in that: The pre-embedded layer includes at least one of a metal single substance, a metal alloy and a metal compound of magnesium.

11. The method for manufacturing a battery according to claim 9, characterized in that: The ion exchange capacity of the polymer material is greater than or equal to 0.2 meq / g.

12. The method for manufacturing a battery according to claim 9, characterized in that: The general structural formula of the coating layer is: Wherein, the R1 and the Mg 2+ Coordination cross-linking, n>0, m≥0.

13. The method for manufacturing a battery according to claim 12, characterized in that: The R1 includes at least one of a carboxyl group, an amide group, an aromatic acid group and a sulfonate group.

14. The method for manufacturing a battery according to claim 12 or 13, characterized in that: The R2 is at least one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a nitro group, an alcohol group, an amino group or a cyano group.

15. The method for manufacturing a battery according to claim 12 or 13, characterized in that: n≥m.

16. The method for manufacturing a battery according to claim 12 or 13, characterized in that: 10<n<10000, 10<m<10000.

17. A battery, characterized in that: include: The negative electrode sheet comprises a negative electrode active material layer and a functional layer stacked together, wherein the functional layer comprises Mg 2+ , part of the Mg 2+ embedded in the negative electrode active material layer; as well as A diaphragm, comprising a base film and a coating layer located on the surface of the base film, wherein the coating layer bonds the base film and the functional layer; Wherein, the coating layer includes a polymer material, and the polymer material and the remaining at least part of the Mg in the functional layer 2+ Coordination cross-linking; The general structural formula of the polymer material is: Wherein, the R1 is used to 2+ Coordination cross-linking, the n>0, the m≥0; the R1 includes at least one of a carboxyl group, an amide group, an aromatic acid group and a sulfonate group.

18. The battery according to claim 17, characterized in that The R2 is at least one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a nitro group, an alcohol group, an amino group or a cyano group.

19. The battery according to claim 17, characterized in that n≥m.

20. The battery according to claim 17, characterized in that 10<n<10000, 10<m<10000.

21. The battery according to claim 17, characterized in that The bonding strength between the negative electrode plate and the separator is greater than 0.5 N / m.

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