Composite Material, Method for Producing the Same, Electrode, Secondary Battery, and Power Consumption Device

Abstract

The present application provides a composite material including a negative electrode active material, dielectric material particles, and a binder resin, at least a portion of the surface of the dielectric material particles being coated with a coupling agent that crosslinks the dielectric material particles and the binder resin.

Description

[Technical field]

[0001] The present application relates to the field of battery technology, in particular to a composite material and a method for producing the same, an electrode, a secondary battery, and a power consuming device. [Background technology]

[0002] In recent years, with the ever-expanding application range of secondary batteries, secondary batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. As secondary batteries have developed rapidly, higher requirements have been put forward for their energy density, cycle characteristics, etc.

[0003] During the operation of lithium-ion batteries, there is a risk of lithium dendrites forming on the negative electrode, and because the conductivity of lithium dendrites is much higher than that of the negative electrode sheet, lithium ions preferentially gather at the ends of lithium dendrites, which causes macroscopic lithium deposition. Macroscopic lithium deposition will bypass the separator and form micro-short circuits with the positive electrode, causing problems such as storage, self-discharge, leakage current, and even penetrating the separator, causing serious problems such as short circuits. Summary of the Invention

[0004] In view of the above problems, the present application provides a new type of composite material and its manufacturing method, an electrode, a secondary battery and a power consuming device, which are described below.

[0005] According to a first aspect, the present application provides a method for producing a method for manufacturing a semiconductor device comprising: A negative electrode active material; Particles of a dielectric material; a binder; and a composite material comprising: At least a portion of the surface of the dielectric material particles is coated with a coupling agent that crosslinks the dielectric material particles and the binder.

[0006] The dielectric particles in the composite material of the present application are crosslinked to the binder resin via a coupling agent, which can provide the following beneficial effects:

[0007] (1) The dielectric material particles are uniformly dispersed in the electrode paste and do not all settle to the bottom of the paste.

[0008] (2) The dielectric material particles can be adhered to the surface of the negative electrode active material by the binder, and are close to the surface of the negative electrode active material, thereby fully exerting the modifying effect.

[0009] Take lithium-ion batteries as an example. During the rapid charging process, the negative active material of lithium-ion batteries will insert lithium ions, which will cause a wide concentration gradient distribution due to the difference in the desolvation speed of solvated lithium at the interface of the SEI film. The enrichment of lithium ions at the interface between the SEI film and the negative electrode will cause local excess lithium content. When the enrichment of lithium ions exceeds the insertion amount of lithium ions, the lithium ions will combine electrons to form lithium dendrites locally at the negative electrode. Since the conductivity of lithium dendrites is much higher than that of the negative electrode sheet, the subsequent lithium ions will preferentially gather at the ends of the lithium dendrites, which will then cause macroscopic lithium precipitation. These lithium precipitations will bypass the separator and form micro-short circuits with the positive electrode, causing problems such as storage, self-discharge, leakage current, and even penetrate the separator, causing serious problems such as short circuits. The high dielectric constant material has a dielectric constant close to that of the electrolyte, which can effectively reduce the desolvation barrier, improve the desolvation level of lithium, and improve the fast charging performance. When such a material is subjected to an electric field, a reverse electric field is generated, and a thin SEI film is formed at the three-phase interface of the dielectric constant material, graphite or silicon, and the solvent, which reduces the loss of active lithium and at the same time shortens the migration path of lithium ions in the SEI film, thereby improving the fast charging performance and reducing the consumption of electrolyte.

[0010] The composite material of the present application is used in the negative electrode of a secondary battery, which can exhibit one or more of improved performance including increased specific capacity, increased first coulombic efficiency, and improved fast charge cycle life.

[0011] (3) The negative electrode active material expands and contracts in volume during the charge and discharge process, and during this process, the dielectric material particles are bridged by the binder resin, so the dielectric material particles do not fall off due to the expansion and contraction of the negative electrode active material, and do not lose contact with the negative electrode active material. The dielectric material particles maintain stable contact with the negative electrode active material during the battery operation process, and can stably exert their modifying effect.

[0012] In some embodiments, the binder adheres the dielectric material particles to the negative electrode active material.

[0013] In some embodiments, the dielectric constant of the dielectric material particles is 80 to 200. By this means, the dielectric constants of the dielectric material particles and the electrolyte are close to each other, and the fast charging performance is better.

[0014] In some embodiments, the dielectric material is selected from one or more of barium titanate, lead titanate, lithium niobate, lead zirconate titanate, lead metaniobate, and barium lead lithium niobate.

[0015] In some embodiments, the binder is an organic binder.

[0016] In some embodiments, the binder is selected from one or more of polyacrylic acid (PAA), styrene butadiene rubber (SBR), polyamide imide (PAI), polyvinyl alcohol (PVA), polyetherimide (PEI), polyimide binder (PI), polyacryl tert-butyl-triethoxyvinylsilane (TBATEVS).

[0017] In some embodiments, the coupling agent is selected from one or more of a silane coupling agent, a titanate coupling agent.

[0018] In some embodiments, the coupling agent is selected from one or more of silane coupling agent KH590, silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH570, silane coupling agent KH792, silane coupling agent DL602, silane coupling agent DL171, chelate 100 type titanate coupling agent, chelate 200 type titanate coupling agent.

[0019] In some embodiments, the coupling agent is attached to the dielectric material via a first terminal functional group that comprises --O--.

[0020] In some embodiments, the coupling agent is attached to the binder through a second terminal functional group that comprises -S-.

[0021] In some embodiments, the coupling agent is attached to the dielectric material via a first terminal functional group that comprises -Si-O-.

[0022] In some embodiments, the coupling agent is attached to the binder through a second terminal functional group that comprises -CS-.

[0023] In some embodiments, the binder has a number average molecular weight of 1 million to 2 million.

[0024] In some embodiments, the dielectric material particles are zero-dimensional particles.

[0025] In some embodiments, the dielectric material particles are tetragonal barium titanate particles.

[0026] In some embodiments, the dielectric material particles have a volume average particle size of 50 nm to 200 nm, which allows the dielectric material particles to be well bonded to the negative electrode active material, and the dielectric material particles are less likely to fall off from the surface of the negative electrode active material.

[0027] In some embodiments, the negative electrode active material has a volume average particle size of 4 to 10 μm, which allows the dielectric material to be favorably attached to the surface of the negative electrode active material and is less likely to fall off.

[0028] In some embodiments, the ratio of the volume average particle size of the negative electrode active material to the volume average particle size of the dielectric material particles is 200: 1 to 20: 1. This makes it possible for the dielectric material to easily adhere to the surface of the negative electrode active material and to be less likely to fall off.

[0029] In some embodiments, the mass ratio of the dielectric material to the binder is from 0.1:100 to 1:100.

[0030] According to a second aspect, the present application provides a method for producing a composite material according to any one of the above claims, The manufacturing method includes the following steps (1) to (4): (1) A hydroxylation treatment is performed on the dielectric material particles to obtain hydroxylated dielectric material particles.

[0031] (2) grafting a coupling agent onto the hydroxylated dielectric material particles to obtain coupling agent-grafted dielectric material particles.

[0032] (3) The coupling agent grafted onto the dielectric material particles is bonded to the binder by a condensation reaction.

[0033] (4) The product of the previous step is mixed with the negative electrode active material.

[0034] In some embodiments, in step (3), the coupling agent on the dielectric material particles comprises a mercapto end group and the binder comprises an alkenyl end group, and the coupling agent is attached to the binder via a mercapto-alkenyl click reaction.

[0035] In some embodiments, the mercapto-alkenyl click reaction is carried out under the action of a photoinitiator and ultraviolet light.

[0036] According to a third aspect, there is provided an electrode comprising the composite material according to any one of the above claims.

[0037] According to a fourth aspect, the present application provides a secondary battery comprising the electrode according to any one of the above claims.

[0038] According to a fifth aspect, the present application provides a power consuming device including the secondary battery described above. Effect of the Invention

[0039] One or more embodiments of the present application may have one or more of the following beneficial effects.

[0040] (1) The composite material is used in an electrode of a secondary battery, and the secondary battery shows improved negative electrode capacity.

[0041] (2) The composite material is used in electrodes of secondary batteries, and the secondary batteries show improved first coulombic efficiency.

[0042] (3) The composite material is used in an electrode of a secondary battery, and the secondary battery exhibits reduced charging resistance.

[0043] (4) The composite material is used in electrodes of secondary batteries, which exhibit long cycle life. [Brief description of the drawings]

[0044] [Figure 1] FIG. 2 is a schematic diagram of a styrene butadiene rubber-barium titanate particle composite according to one embodiment of the present application. [Diagram 2] FIG. 2 is an infrared spectrum diagram of a styrene butadiene rubber-barium titanate particle composite and barium titanate particles according to one embodiment of the present application. [Diagram 3] FIG. 1 is a schematic diagram of a composite material according to an embodiment of the present application. [Figure 4] FIG. 2 is a schematic diagram of an adhesion measurement according to an embodiment of the present application. [Diagram 5] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Figure 6] FIG. 6 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 5. [Figure 7] FIG. 1 is a schematic diagram of a battery module according to an embodiment of the present application. [Figure 8] FIG. 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 9] FIG. 9 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 8. [Figure 10] 1 is a schematic diagram of a power consuming device that uses a secondary battery as a power source according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Hereinafter, the embodiments specifically disclosing the negative electrode active material and its manufacturing method, positive electrode sheet, negative electrode sheet, secondary battery, battery module, battery pack and device of the present application will be described in detail with reference to the drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and overlapping description of substantially the same structure may be omitted. This is to prevent the following description from being unnecessarily redundant and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0046] The "ranges" disclosed herein are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner may or may not include the endpoints and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are recited for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Also, if minimum range values ​​1 and 2 are recited, and maximum range values ​​3, 4, and 5 are recited, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all contemplated. In this application, unless otherwise stated, the numerical range "a-b" means a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are recited herein, and "0-5" is merely a shorthand for combinations of these numerical values. Furthermore, expressing a parameter as an integer ≧2 is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0048] All technical features and optional technical features in the present application can be combined with each other to form new technical solutions, unless otherwise stated.

[0049] All steps of the present application can be carried out in order or randomly unless otherwise specified, and preferably in order. For example, if the method includes steps (a) and (b), it indicates that the method may include steps (a) and (b) carried out in order, or steps (b) and (a) carried out in order. For example, if it is said that the method may further include step (c), it means that step (c) may be added to the method in any order. For example, it indicates that the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0050] As used in the present application, unless otherwise specified, the terms "comprising" and "including" indicate both open and closed forms. For example, the said "comprising" and "including" can indicate that other components not listed may also be included or encompassed, or can indicate that only the listed components may be included or encompassed.

[0051] In the present application, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by either A being true (or existing) and B being false (or not existing), or A being false (or not existing) and B being true (or existing), or both A and B being true (or existing).

[0052] [Secondary battery] A secondary battery is also called a rechargeable battery or a storage battery, and it is a battery that can continue to be used by activating the active material in a way that the battery is charged after discharging.

[0053] In general, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charge and discharge process of the battery, active ions (e.g., lithium ions) shuttle between the positive electrode sheet and the negative electrode sheet to be inserted and removed. The separator is installed between the positive electrode sheet and the negative electrode sheet, and mainly serves to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through. The electrolyte mainly serves to conduct the active ions between the positive electrode sheet and the negative electrode sheet.

[0054] [Composite materials] According to a first aspect, the present application provides a method for producing a method for manufacturing a semiconductor device comprising: A negative electrode active material; Particles of a dielectric material; a binder; and a composite material comprising: At least a portion of the surface of the dielectric material particles is coated with a coupling agent that crosslinks the dielectric material particles and the binder.

[0055] The dielectric particles in the composite material of the present application are crosslinked to the binder resin via a coupling agent, which can provide the following beneficial effects:

[0056] (1) The dielectric material particles are uniformly dispersed in the electrode paste and do not all settle to the bottom of the paste.

[0057] (2) The dielectric material particles can be adhered to the surface of the negative electrode active material by the binder, and are close to the surface of the negative electrode active material, thereby fully exerting the modifying effect.

[0058] (3) The negative electrode active material expands and contracts in volume during the charge and discharge process, and during this process, the dielectric material particles are bridged by the binder resin, so the dielectric material particles do not fall off due to the expansion and contraction of the negative electrode active material, and do not lose contact with the negative electrode active material. The dielectric material particles maintain stable contact with the negative electrode active material during the battery operation process, and can stably exert their modifying effect.

[0059] In some embodiments, the term "bridged" means that one end of the coupling agent is connected to a particle of dielectric material and the other end is connected to the binder via a chemical bond.

[0060] In some embodiments, the term "connected" refers to connection via a chemical bond, such as an ionic or covalent bond.

[0061] In some embodiments, the coupling agent and the dielectric material particles are bonded via a chemical bond.

[0062] In some embodiments, the coupling agent and binder are bonded via a chemical bond.

[0063] The term "coupling agent" refers to a substance capable of bonding to both the dielectric material and the binder, respectively. The "coupling agent" can have two functional groups of different nature, for example, one is an inorganic affinity functional group that is easily chemically reacted with the surface of inorganic matter, and the other is an organophilic agent that can chemically react with, physically entangle or form hydrogen bonds with synthetic resins or other polymers.

[0064] In some embodiments, the binder adheres the dielectric material particles to the negative electrode active material.

[0065] In some embodiments, the dielectric constant of the dielectric material particles is between 80 and 200 (eg, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200).

[0066] In some embodiments, the dielectric material is selected from one or more of barium titanate, lead titanate, lithium niobate, lead zirconate titanate, lead metaniobate, and barium lead lithium niobate.

[0067] In some embodiments, the general chemical formula of lead zirconate titanate is Pb x Zr1-x TiO 3 and 0 <x<1である。

[0068] In some embodiments, the general chemical formula of lead barium lithium niobate is (Pb x Ba 1-x ) 4 Li 2 Nb 10 O 30 and 0 <x<1である。

[0069] In some embodiments, the binder is an organic binder.

[0070] In some embodiments, the binder has one or more (eg, one, two, or three) selected from the monomer units shown in Formula 1, Formula 2, and Formula 3.

[0071] [ka] In some embodiments, the binder is selected from one or more of polyacrylic acid (PAA), styrene butadiene rubber (SBR), polyamide imide (PAI), polyvinyl alcohol (PVA), polyetherimide (PEI), polyimide binder (PI), polyacryl tert-butyl-triethoxyvinylsilane (TBATEVS).

[0072] In some embodiments, the coupling agent is selected from one or more of a silane coupling agent, a titanate coupling agent.

[0073] In some embodiments, the coupling agent is selected from one or more of silane coupling agent KH590, silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH570, silane coupling agent KH792, silane coupling agent DL602, silane coupling agent DL171, chelate 100 type titanate coupling agent, chelate 200 type titanate coupling agent.

[0074] In some embodiments, the coupling agent is a silane coupling agent of the general formula RSiX3, where R represents groups such as amino, mercapto, vinyl, epoxy, cyano, and methacryloyloxy, which have strong reactive capabilities with any of a variety of base resins, and X represents a hydrolyzable alkoxy group (e.g., methoxy, ethoxy, etc.). The silane coupling agent is one or more of KH550, KH560, KH590, KH570, KH792, DL602, and DL171.

[0075] In some embodiments, the coupling agent is a chelate-type titanate coupling agent. Specifically, it may be one or more of chelate 100 type and chelate 200 type. The chelate 100 type is a titanate coupling agent containing an oxyacetic acid chelating group, and the chelate 200 type is a titanate coupling agent containing an ethylene glycol chelating agent. An example of the chelate 100 type titanate coupling agent is bis(octylpyrophosphate) glycolate titanate CTDPP-138S (KR-138S). An example of the chelate 200 type titanate coupling agent is ethylene diglycol bisphosphate ETDOP-212S (KR-212S).

[0076] In some embodiments, the coupling agent is selected from one or more of silane coupling agent KH590, silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH570, silane coupling agent KH792, silane coupling agent DL602, silane coupling agent DL171, chelate 100 type titanate coupling agent, chelate 200 type titanate coupling agent.

[0077] In some embodiments, the coupling agent is attached to the dielectric material via a first terminal functional group that comprises --O--.

[0078] In some embodiments, the coupling agent is attached to the binder through a second terminal functional group that comprises -S-.

[0079] In some embodiments, the coupling agent is attached to the dielectric material via a first terminal functional group that comprises -Si-O-.

[0080] In some embodiments, the coupling agent is attached to the binder through a second terminal functional group that comprises -CS-.

[0081] In some embodiments, the number average molecular weight of the binder is from 1 million to 2 million, such as from 1.3 million to 1.7 million, for example, 1.5 million.

[0082] In some embodiments, the term "number average molecular weight" refers to the general arithmetic average of the molecular weights of each polymer.

[0083] In some embodiments, the dielectric material particles are zero-dimensional particles, which refers to point-like material in all three dimensions in the nanoscale range (1-100 nm, e.g., 1-50 nm, e.g., 1-10 nm).

[0084] In some embodiments, the dielectric material particles are tetragonal barium titanate particles.

[0085] In some embodiments, the volume average particle size of the dielectric material particles is 50 nm to 200 nm, for example, 50 nm to 100 nm, 100 nm to 150 nm, or 150 nm to 200 nm. The advantage of the volume average particle size of the dielectric material particles being in the above range is that the dielectric material particles are easily mixed with a negative electrode active material such as graphite, and are less likely to fall off from the graphite surface.

[0086] In some embodiments, the term "volume average particle size" Dv50 refers to the particle size corresponding to 50% of the volume in a cumulative particle distribution ordered from the smallest size to the largest size. The "volume average particle size" may be obtained by observation and measurement using a scanning electron microscope, or may be obtained by measurement using a laser diffraction method.

[0087] In some embodiments, the negative electrode active material has a volume average particle size of 4 to 10 μm.

[0088] In some embodiments, the ratio of the volume average particle diameter of the negative electrode active material to the dielectric material particles is 200:1 to 20:1, for example, 200:1 to 150:1, 150:1 to 100:1, 100:1 to 50:1, or 50:1 to 20:1. The advantage of the ratio of the volume average particle diameter of the negative electrode active material to the dielectric material particles being in the above range is that the dielectric material easily adheres to the graphite surface and is less likely to fall off.

[0089] In some embodiments, the mass ratio of the dielectric material to the binder is 0.1:100 to 1:100 (e.g., 0.1:100 to 0.2:100, 0.2:100 to 0.3:100, 0.3:100 to 0.4:100, 0.4:100 to 0.5:100, 0.5:100 to 0.6:100, 0.6:100 to 0.7:100, 0.7:100 to 0.8:100, 0.8:100 to 0.9:100, 0.9:100 to 1:100).

[0090] In some embodiments, the term "zero dimensional" refers to particles in a state where the particle size is very small and has virtually no length, such as a nanoparticle state. In contrast to the term "zero dimensional," the term "three dimensional" refers to a state of a large volume having a volume, the term "two dimensional" refers to a thin film state, and the term "one dimensional" refers to a nanotube state.

[0091] In some embodiments, the term "0 dimensional" refers to particles with a diameter of 1 nm to about 100 nm (1-10 nm, 10-20 nm, 20-30 nm, 30-40 nm, 40-50 nm, 50-60 nm, 60-70 nm, 70-80 nm, 80-90 nm, 90-100 nm).

[0092] In some embodiments, the term "tetragonal" refers to a crystal structure having a unit cell containing three axes, two of which are of equal length and perpendicular to each other, and a third axis which is perpendicular to the other two.

[0093] In some embodiments, the term “dielectric constant” refers to the dielectric constant (ε r ) and the relative dielectric constant of a material is compared to the relative dielectric constant of a vacuum (ε 0 ) is the result.

[0094] In some embodiments, the dielectric constant ε refers to the dielectric constant at room temperature (25±5° C.), and has a meaning known in the art and can be measured using devices and methods known in the art. For example, after preparing a circular sample of a ferroelectric material, the capacitance C is measured with an LCR meter and the dielectric constant ε is calculated according to the formula: 0 × A), where C is the capacitance in Farads (F), d is the thickness of the sample in cm, and A is the area of ​​the sample in cm. 2 and ε 0 denotes the vacuum dielectric constant, and ε 0 =8.854×10-14F / cm. In this application, the measurement conditions may be 1KHz, 1.0V, and 25±5℃. The measurement standard may conform to GB / T 11297.11-2015. When making samples, reference may be made to Chinese patent application CN114217139A.

[0095] In some embodiments, the dielectric constant of the present application may be measured through a dielectric constant measuring device, specifically referring to GB / T5594.4-1985, and the device may select ZJD-C dielectric constant measuring device from Beijing China Aviation Times Instrument Equipment Co., Ltd.

[0096] According to a second aspect, the present application provides a method for producing a composite material according to any one of the above claims, The manufacturing method includes the following steps (1) to (4): (1) A hydroxylation treatment is performed on the dielectric material particles to obtain hydroxylated dielectric material particles.

[0097] (2) grafting a coupling agent onto the hydroxylated dielectric material particles to obtain coupling agent-grafted dielectric material particles.

[0098] (3) The coupling agent grafted onto the dielectric material particles is bonded to the binder by a condensation reaction.

[0099] (4) The product of the previous step is mixed with the negative electrode active material.

[0100] In some embodiments, in step (3), the coupling agent on the dielectric material particles comprises a mercapto end group and the binder comprises an alkenyl end group, and the coupling agent is attached to the binder via a mercapto-alkenyl click reaction.

[0101] In some embodiments, the mercapto-alkenyl click reaction is carried out under the action of a photoinitiator and ultraviolet light.

[0102] According to a third aspect, there is provided an electrode comprising the composite material according to any one of the above claims.

[0103] According to a fourth aspect, the present application provides a secondary battery comprising the electrode according to any one of the above claims.

[0104] According to a fifth aspect, the present application provides a power consuming device including the secondary battery described above.

[0105] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material using any one of the negative electrode active materials of the present application.

[0106] As an example, the negative electrode current collector has two opposing surfaces in the thickness direction of the negative electrode current collector, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

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

[0108] In some embodiments, the negative electrode active material may be a known negative electrode active material for batteries. As an example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like. The silicon-based material may be selected from at least one of silicon alone, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of tin alone, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as a negative electrode active material for a battery may be used. These negative electrode active materials may be used alone or in combination of two or more types.

[0109] In some embodiments, the negative electrode film layer may further include a binder. For example, the binder may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0110] In some embodiments, the negative electrode film layer may further include an optional conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0111] In some embodiments, the negative electrode film layer optionally further comprises other auxiliary agents, such as a thickening agent (eg, sodium carboxymethylcellulose (CMC-Na)).

[0112] In some embodiments, the negative electrode sheet can be manufactured in the following manner: Components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode paste, which is then applied to a negative electrode current collector, and the negative electrode sheet can be obtained through steps such as drying and cold pressing.

[0113] [Positive electrode sheet] In some embodiments, the positive electrode sheet generally comprises a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0114] As an example, the positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode film layer is provided on either or both of the two opposing surfaces of the positive electrode current collector.

[0115] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. The metal foil can be, for example, an aluminum foil. The composite current collector can include a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0116] In some embodiments, the positive electrode active material may be a known positive electrode active material for batteries. As an example, the positive electrode active material may include at least one of a lithium-containing phosphate having an olivine structure, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials usable as a positive electrode active material for batteries may be used. These positive electrode active materials may be used alone or in combination of two or more. An example of a lithium transition metal oxide is lithium cobalt oxide (e.g., LiCoO 2 ), lithium nickel oxide (e.g. LiNiO 2 ), lithium manganese oxide (e.g. LiMnO 2 , LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g. LiNi 1 / 3 Co 1 / 5 n 1 / 3 O 2 (Abbreviation: NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (Abbreviation: NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (Abbreviation: NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (Abbreviation: NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (Abbreviation: NCM 811 )), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and modified compounds thereof, but are not limited thereto. Examples of lithium-containing phosphates having an olivine structure include, for example, lithium ferric phosphate (e.g., LiFePO 4 (abbreviation: LFP), lithium ferric phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO 4 ), a composite of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite of lithium iron manganese phosphate and carbon.

[0117] In some embodiments, the positive electrode film layer can further include a binder. For example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0118] In some embodiments, the positive electrode film layer can optionally further include a conductive agent, for example, the conductive agent can include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0119] In some embodiments, the positive electrode sheet can be manufactured by the following method: Components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, and the positive electrode slurry is applied to a positive electrode current collector, followed by steps such as drying and cold pressing to obtain a positive electrode sheet.

[0120] [Electrolytes] The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The present application does not particularly limit the type of electrolyte, and it can be selected as needed. For example, the electrolyte may be liquid, gel, or completely solid.

[0121] In some embodiments, the electrolyte is a liquid and includes an electrolyte salt and a solvent.

[0122] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bisoxalate borate, lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0123] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0124] In some embodiments, the electrolyte solution further includes an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include an additive that can improve a specific characteristic of the battery, such as an additive that improves the overcharge characteristic of the battery, or an additive that improves the high-temperature or low-temperature characteristic of the battery.

[0125] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of the separator, and any known porous structure separator having good chemical stability and mechanical stability can be selected.

[0126] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, and is not particularly limited.

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

[0128] In some embodiments, the secondary battery may include a housing material, which is used to encapsulate the electrode assembly and the electrolyte.

[0129] In some embodiments, the exterior material of the secondary battery may be a hard case such as a hard plastic case, an aluminum case, a steel case, etc. The exterior material of the secondary battery may be a soft pack such as a pouch-type soft pack, etc. The material of the soft pack may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0130] The present application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, FIG. 5 shows a secondary battery 5 having a rectangular structure as an example.

[0131] In some embodiments, referring to FIG. 6, the exterior may include a housing 51 and a cover plate 53. The housing 51 includes a bottom plate and a side plate connected to the bottom plate, and a receiving cavity surrounded by the bottom plate and the side plate is formed. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 may cover the opening to seal the receiving cavity. The electrode assembly 52 may be formed from a positive electrode sheet, a negative electrode sheet and a separator through a winding process or a stacking process. The electrode assembly 52 is sealed in the receiving cavity. An electrolyte is impregnated in the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and may be selected by those skilled in the art according to specific practical requirements.

[0132] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module can be one or more, with the specific number being selectable by those skilled in the art according to the application and capacity of the battery module.

[0133] Fig. 7 shows an example of a battery module 4. Referring to Fig. 7, in the battery module 4, a plurality of secondary batteries 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they may be arranged in any other manner. The plurality of secondary batteries 5 can be fixed by fasteners.

[0134] Optionally, the battery module 4 may further include an outer case having an accommodation space in which a plurality of secondary batteries 5 are accommodated.

[0135] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0136] 8 and 9 show an example of a battery pack 1. Referring to Fig. 8 and Fig. 9, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed in the battery case. The battery case includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be placed over the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery case in any manner.

[0137] The present application further provides a power consuming device including at least one of the secondary battery, battery module, or battery pack according to the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consuming device, or may be used as an energy storage element for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships, satellites, energy storage systems, etc.

[0138] The power consumption device can be selected as a secondary battery, a battery module or a battery pack according to its usage requirements.

[0139] 10 shows an example of a power consumption device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements for the secondary battery of the power consumption device, a battery pack or a battery module can be used.

[0140] The following is a description of the examples of the present application. The examples described below are illustrative and are only intended to explain the present application, and should not be understood as limiting the present application. If no specific techniques or conditions are shown in the examples, they are carried out according to the techniques or conditions described in the literature in this field, or according to the product instructions. If no manufacturer is listed for the reagents or equipment used, they are all commercially available general products.

[0141] Example 1 100 g of dielectric material particles (barium titanate particles, tetragonal crystal system) were added to 1 L of H 2 O 2 Add to the solution (H 2 O 2 The concentration is 3%, and then 50 mL of ammonium chloride solution is added, and the mixture is heated and stirred at a reflux temperature of 90 °C for 3 h to obtain hydroxy-modified barium titanate particles.

[0142] 100 g of hydroxy-modified barium titanate particles are immersed in an aqueous ethanol solution (the volume ratio of ethanol to water is 8:1), 10 mL of a coupling agent (γ-mercaptopropyltrimethoxysilane) is added, and the mixture is heated to 50°C and reacted for 4 hours to obtain barium titanate particles grafted with the coupling agent.

[0143] 200g of binder (styrene butadiene rubber, number average molecular weight is 1.5 million) copolymer is dissolved in 1L of DMF, ultrasonically stirred, 10g of barium titanate particles grafted with coupling agent are added, and 9g of benzoin dimethyl ether is further added to obtain a mixture. The above mixture is irradiated with a 360nm ultraviolet lamp for 30 minutes, and further heated at 30℃ until the DMF volatilizes to obtain a styrene butadiene rubber-barium titanate particle composite.

[0144] In a styrene-butadiene rubber-barium titanate particle composite (abbreviation: SBR-BTO), at least a portion of the surface of the barium titanate particle is coated with γ-mercaptopropyltrimethoxysilane silane, which crosslinks the barium titanate particle and the styrene-butadiene rubber.

[0145] FIG. 1 is a schematic diagram of a styrene butadiene rubber-barium titanate particle composite, in which at least a portion of the surface of a dielectric material particle 101 is coated with a coupling agent 102 that bridges the dielectric material particle 101 with a binder 103, as shown.

[0146] Figure 2 shows the infrared spectrum of barium titanate particles grafted with styrene butadiene rubber (BTO-SBR). As can be seen from the figure, the infrared spectrum of barium titanate particles at wave numbers of 1200 and 1100 cm -1 The absorption peaks of Si-C and Si-O were observed at the position, which proves that the γ-mercaptopropyltrimethoxysilane silane crosslinks the barium titanate particles and the styrene-butadiene rubber together.

[0147] A negative electrode active material (artificial graphite), a conductive agent (acetylene black), styrene butadiene rubber grafted barium titanate particles (abbreviation: SBR-BTO) and a dispersant (sodium carboxymethyl cellulose, abbreviation: CMC) are mixed in a weight ratio of 97:1:1:1 to obtain a composite material of Example 1. The composite material is then used to manufacture a negative electrode paste of a lithium ion battery. The ratio of the volume average particle size of the negative electrode active material and the dielectric material particles is controlled to 50:1, that is, the volume average particle size of the negative electrode active material in Example 1 is 2.5 μm.

[0148] FIG. 3 is a schematic diagram of a composite material, as shown in the figure, the composite material includes a negative electrode active material 100, a dielectric material particle 101, and a binder 103, and the binder 103 adheres the dielectric material particle 101 to the negative electrode active material 100. As shown in FIG. 3, the above-mentioned means of the present application manufactures a composite material with a "throwing hammer-like structure", and connects the binder 103 and the dielectric material particle 101 through a mercapto group, so that the hydroxyl group on the surface of the binder 103 can be connected to the surface of the negative electrode active material 100 through hydrogen bonds, and the dielectric material particle 101 can be uniformly distributed on the surface of the negative electrode active material 100. At the same time, such a composite material achieves point-to-point connection at the negative electrode end, improves the utilization rate of the high dielectric constant material, fully exerts its desolvation effect and thin SEI performance, and does not block the lithium ion migration channel. Note that FIG. 3 is merely a schematic diagram for easily showing the connection relationship, and the size relationship in FIG. 3 does not represent the actual size relationship.

[0149] The ratios of the raw material components (artificial graphite, acetylene black, SBR-BTO, CMC) of the composite material produced in Example 1, the ratio of SBR to BTO in SBR-BTO, the volume average particle size Dv50 and relative dielectric constant of barium titanate, and the number average molecular weight of SBR are as shown in Table 1.

[0150] Examples 2 to 15 Examples 2 to 15 differ from Example 1 in that the raw material parameters or process parameters for producing the composite material are different. Specific parameter differences are as shown in Table 1.

[0151] In Example 11, lead titanate (PTO) was used in place of barium titanate (BTO) in Example 1.

[0152] In Example 12, lithium niobate (PPLN) was used in place of barium titanate (BTO) in Example 1.

[0153] In Example 13, lead zirconate titanate (PZT) was used in place of barium titanate (BTO) in Example 1.

[0154] Example 14 used a Chelate 100 type titanate coupling agent (CTDPP-138S) to crosslink the dielectric particles and the binder instead of the gamma-mercaptopropyltrimethoxysilane of Example 1.

[0155] Example 15 used a Chelate 200 type titanate coupling agent (ETDOP-212S) to crosslink the dielectric particles and the binder instead of the gamma-mercaptopropyltrimethoxysilane of Example 1.

[0156] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is the composition of the composite material. The composite material of Comparative Example 1 does not contain BTO dielectric material particles. The composite material of Comparative Example 1 is composed of a negative electrode active material (artificial graphite), a conductive agent (acetylene black), a styrene butadiene rubber, and a dispersant (sodium carboxymethylcellulose) mixed in a weight ratio of 97:1:1:1.

[0157] Comparative Example 2 The difference between Comparative Example 2 and Example 1 lies in the different formulations of the composite materials. The composite material of Comparative Example 2 does not contain the dielectric material particles BTO. The formulation of the composite material of Comparative Example 2 is to mix a negative electrode active material (artificial graphite), a conductive agent (acetylene black), styrene-butadiene rubber, dielectric material particles (barium titanate particles), and a dispersant (sodium carboxymethyl cellulose) in a weight ratio of 97:1:0.95::0.05:1.

[0158] Manufacture of the full cell (1) Manufacture of the negative electrode sheet: The composite materials of the above Examples and Comparative Examples are respectively added to deionized water and stirred and mixed uniformly to manufacture a negative electrode paste. The negative electrode paste is coated on a copper foil of a negative electrode current collector with a thickness of 7 μm, and after drying, cold pressing, and cutting, a negative electrode sheet having a negative electrode film layer is obtained, and the areal density of the negative electrode film layer is 9.7 mg / cm 2 It is.

[0159] (2) Manufacture of the positive electrode sheet: Lithium nickel cobalt manganate (NCM523, that is, LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), polyvinylidene fluoride (PVDF), and acetylene black SP as a conductive agent are mixed in a mass ratio of 98:1:1, and N-methylpyrrolidone (NMP) is added as a solvent, and the mixture is stirred in a vacuum state until the paste becomes uniform. The obtained paste is coated on an aluminum foil with a thickness of 13 μm with a scraper, and after drying, cold pressing, and cutting at 140 °C, a positive electrode sheet having a positive electrode film layer is obtained, and the areal density of the positive electrode film layer is 13.7 mg / cm 2 It is.

[0160] (3) Electrolyte: In a glove box under an argon atmosphere (H 2 O <0.1 ppm, O 2 <0.1 ppm), ethylene carbonate (EC) / ethyl methyl carbonate (EMC) as an organic solvent are uniformly mixed in a volume ratio of 3:7 to obtain a solvent, and 12.5% by weight (based on the total weight of the ethylene carbonate / ethyl methyl carbonate solvent) of LiPF 6The electrolyte is dissolved in the organic solvent and stirred to obtain an electrolyte solution having a relative dielectric constant of 90.

[0161] (4) Separator: A commercially available PP-PE copolymer microporous film having a thickness of 20 μm and an average pore size of 80 nm (obtained from Zhuo Gao Electronics Technology Co., Ltd., model number 20) is used.

[0162] (5) The positive electrode sheet, the separator, and the negative electrode sheet are stacked in this order, and the separator is placed between the positive and negative electrodes to serve as an insulator, and then wound up to obtain a bare cell. The bare cell is placed in an outer casing, and the above-mentioned electrolyte is injected and sealed to obtain a secondary battery.

[0163] Half-cell fabrication The same negative electrode sheet and electrolyte as the full battery are used, and a lithium sheet is used for the electrode, and assembled into a button-type half cell.

[0164] Analysis and Measurement 1. Testing the adhesive strength of polar sheets An adhesive strength test was performed using a peel test method. (a) to (d) of FIG. 4 are a flowchart of the peel test. As shown in (a) of FIG. 4, first, a steel plate 510 with a width of 30 mm and a length of 100 mm is prepared. As shown in (b) of FIG. 4, a double-sided tape 520 with a width of 20 mm and a length of 30 mm is then prepared, and the double-sided tape 520 is attached to the steel plate 510, and one long side of the double-sided tape 520 is aligned with one long side of the steel plate 510. As shown in (c) of FIG. 4, a polar sheet 530 to be measured with a width of 20 mm and a length of 180 mm is then prepared. The polar sheet 530 to be measured is coated on the double-sided tape 520 (both sides are aligned), and the coating surface of the polar sheet 530 faces the double-sided tape 520. Since the length of the polar sheet 530 to be measured is longer than the length of the double-sided tape 520, a part of the area of ​​the polar sheet 530 to be measured is not adhered to the double-sided tape. As shown in FIG. 4(d), the steel plate 510 is fixed to the base of the tensile tester, and the end of the polar sheet 530 to be measured that is not attached to the double-sided tape is clamped by a jig, and the jig is pulled in the direction of the other end (the direction indicated by the arrow), and the direction of the pulling force is perpendicular to the steel plate 510 and there is a certain distance from the surface of the steel plate 510. While pulling the peeled polar sheet toward the outside of the paper, the steel plate is moved upward, and the perpendicularity between the pulling direction and the peeling position of the polar sheet is maintained. During the pulling process, the polar sheet 530 is gradually peeled off from the steel plate by pulling. During the pulling process, the pulling speed of the jig is 50 mm / min. During the pulling process, the pulling force of the jig is recorded, and even after the pulling force becomes stable, a length of 40 mm is peeled off, and the average pulling force in the peeled length is taken as the adhesive force (unit N).

[0165] 2, Negative electrode specific capacity (C) Charge the button battery at 2.5-4.3V at 0.1C up to 4.3V, then charge it at a constant voltage of 4.3V to 0.05mA or less, leave it for 5min, and discharge it at 0.1C down to 2.0V. The discharge capacity at this time is the initial specific capacity. The initial specific capacity is divided by the weight of the positive electrode active material to obtain the positive electrode specific capacity.

[0166] 3. Initial Coulombic Efficiency (ICE) of the negative electrode At 25°C and normal pressure, the button battery is discharged at a constant current of 0.1C until the voltage reaches 0.005V, and then discharged at a constant current of 0.05C until the voltage reaches 0.005V, and the discharge specific capacity at this time is recorded, that is, the initial lithium absorption capacity. It is then charged at a constant current of 0.1C until the voltage reaches 1.5V, and the charge specific capacity at this time is recorded, that is, the initial lithium desorption capacity. The button battery is subjected to 50 cycle charge and discharge tests according to the above method, and the lithium desorption capacity at each time is recorded.

[0167] Initial Coulombic efficiency (%) = Initial lithium desorption capacity / Initial lithium absorption capacity × 100%

[0168] 4. Charging resistance test In this application, the dynamic characteristics of the secondary battery are evaluated by the charging resistance at 25°C and 4C. At 25°C, the lithium ion batteries manufactured in the examples and comparative examples are discharged to 50% capacity, left to stand for 30 minutes, and the voltage value V1 is recorded. They are then charged for 10 seconds at a current A0 corresponding to a rate of 4C, and the voltage value V2 corresponding to the end of charging is recorded. The charging resistance is calculated as R=(V2-V1) / A0. A normalization process is performed on the experimental results. The charging resistance value of Example 2 is set as the reference value of 100, and the example is scaled according to the ratio.

[0169] 5. Fast charging cycle life / cycle number In this application, the capacity retention characteristic of the secondary battery is evaluated based on the fast charging cycle life / cycle number. At 25°C, the lithium ion batteries manufactured in the examples and comparative examples are charged at a rate of 2C and discharged at a rate of 1C, and a continuous cycle test is performed in the SOC range of 3% to 97%. The test is continued until the capacity of the lithium ion battery becomes less than 80% of the initial capacity, and the number of cycles is recorded.

[0170] 6. Dielectric constant test The relative permittivity of the dielectric material particles and the electrolyte in this application may be measured via a relative permittivity measuring device. Specifically, GB / T5594.4-1985 can be referred to, and the ZJD-C relative permittivity measuring device of Beijing Zhonghang Times Instrument Equipment Co., Ltd. may be selected for the device.

[0171] 7. Volume average particle size The volume average particle size Dv50 has the meaning known in this field and can be measured using devices and methods known in this field. For example, referring to GB / T19077-2016 Laser Diffraction Method for Particle Size Distribution, it can be easily measured using a laser particle size analyzer such as the Mastersizer 2000E type laser particle size analyzer of Malvern, UK.

[0172]

Table 1

[0173] It can be seen from the experimental data as follows.

[0174] The negative electrode pastes of Examples 1 to 16 contain the novel composite material of this application. The composite material includes a negative electrode active material (artificial graphite), dielectric material particles (barium titanate particles), and a binder resin (styrene-butadiene rubber). At least a part of the surface of the dielectric material particles is coated with a coupling agent (γ-mercaptopropyltrimethoxysilane) that crosslinks the dielectric material particles and the binder resin.

[0175] The dielectric material particles in the composite material of this application are crosslinked to the binder resin via a coupling agent, which can bring the following beneficial effects.

[0176] (1) The dielectric material particles are uniformly dispersed in the electrode paste and do not all settle to the bottom of the paste.

[0177] (2) The dielectric material particles can be bound to the surface of the negative electrode active material by the binder, and are close to the surface of the negative electrode active material, thereby fully exerting the modifying effect.

[0178] (3) The negative electrode active material expands and contracts in volume during the charge and discharge process, and during this process, the dielectric material particles are bridged by the binder resin, so the dielectric material particles do not fall off due to the expansion and contraction of the negative electrode active material, and do not lose contact with the negative electrode active material. The dielectric material particles maintain stable contact with the negative electrode active material during the battery operation process, and can stably exert their modifying effect.

[0179] In terms of battery performance, the battery of the present application exhibits one or more of the following performances.

[0180] (1) Improved anode capacity (2) Improved first coulombic efficiency (3) Decrease in charging resistance (4) Long cycle life.

[0181] The present application is not limited to the above-mentioned embodiment. The above-mentioned embodiment is merely an example, and any embodiment that has substantially the same configuration as the technical idea and exhibits the same effect within the scope of the technical solution of the present application is included in the technical scope of the present application. In addition, various modifications that a person skilled in the art can conceive of are added to the embodiment, and other forms constructed by combining some of the components in the embodiment are also included in the scope of the present application, as long as they do not deviate from the gist of the present application. [Explanation of symbols]

[0182] 1 Battery pack 2 Upper case 3 Lower case 4 Battery Module 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Cap Assembly 100 Anode active material 101 Dielectric material particles 103 Binder 510 steel plate 520 Double-sided tape 530 Measurement target polarity sheet

Claims

1. A negative electrode active material; Particles of a dielectric material; Including binder, A composite material, wherein at least a portion of the surface of the dielectric material particles is coated with a coupling agent that crosslinks the dielectric material particles and the binder.

2. 10. The composite of claim 1, wherein the binder adheres the dielectric material particles to the negative electrode active material.

3. 2. The composite material of claim 1, wherein the dielectric material particles have a relative dielectric constant of 80-200.

4. 3. The composite material of claim 1, wherein the dielectric material is selected from one or more of barium titanate, lead titanate, lithium niobate, lead zirconate titanate, lead metaniobate, barium lead lithium niobate.

5. The composite material according to any one of claims 1 to 4, wherein the binder is an organic binder.

6. 6. The composite material of any one of claims 1 to 5, wherein the binder is selected from one or more of polyacrylic acid (PAA), styrene butadiene rubber (SBR), polyamideimide (PAI), polyvinyl alcohol (PVA), polyetherimide (PEI), polyimide binder (PI), polyacryl tert-butyl-triethoxyvinylsilane (TBATEVS).

7. The composite material according to any one of claims 1 to 6, wherein the coupling agent is selected from one or more of a silane coupling agent, a titanate coupling agent.

8. The composite material according to any one of claims 1 to 7, wherein the coupling agent is selected from one or more of silane coupling agent KH590, silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH570, silane coupling agent KH792, silane coupling agent DL602, silane coupling agent DL171, chelate 100 type titanate coupling agent, chelate 200 type titanate coupling agent.

9. The coupling agent is connected to the dielectric material via a first terminal functional group comprising -O-; The composite material of any one of claims 1 to 8, wherein the coupling agent has one or more of the features of (2) connected to the binder via a second terminal functional group comprising -S-.

10. The coupling agent is connected to the dielectric material via a first terminal functional group comprising -Si-O-; The composite material of any one of claims 1 to 8, wherein the coupling agent has one or more of the features of (2) connected to the binder via a second terminal functional group comprising -C-S-.

11. The composite material according to any one of claims 1 to 10, wherein the binder has a number average molecular weight of 1 million to 2 million.

12. The dielectric material particles include The characteristic of being a zero-dimensional particle (1), (2) The particle is a tetragonal barium titanate particle; The volume average particle size is 50 nm to 200 nm (3); The negative electrode active material has a volume average particle diameter of 4 to 10 μm (4); The composite material according to any one of claims 1 to 11, having one or more of the features of feature (5), wherein the ratio of the volume average particle size of the negative electrode active material to the volume average particle size of the dielectric material particles is 200:1 to 20:

1.

13. 13. The composite material according to any one of the preceding claims, wherein the mass ratio of the dielectric material to the binder is from 0.1:100 to 1:

100.

14. A method for producing the composite material according to any one of claims 1 to 3, comprising the steps of: (1) performing a hydroxylation treatment on dielectric material particles to obtain hydroxylated dielectric material particles; (2) grafting a coupling agent onto the hydroxylated dielectric material particles to obtain dielectric material particles having the coupling agent grafted thereon; (3) connecting the coupling agent grafted onto the dielectric material particles with a binder through a condensation reaction; (4) mixing the product of the previous step with a negative electrode active material; A method for producing a composite material comprising the steps of:

15. 15. The method of claim 14, wherein in step (3), the coupling agent on the dielectric material particles comprises a mercapto end group and the binder comprises an alkenyl end group, and the coupling agent is connected to the binder by a mercapto group-alkenyl group click reaction.

16. The method according to claim 15, wherein the mercapto group-alkenyl group click reaction is carried out under the action of a photoinitiator and ultraviolet light.

17. An electrode comprising the composite material according to any one of claims 1 to 13.

18. A secondary battery comprising the electrode according to claim 17.

19. 20. A power consuming device comprising the secondary battery of claim 18.

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