CN117497768A

CN117497768A - Negative electrode plate, preparation method thereof, battery and power utilization device

Info

Publication number: CN117497768A
Application number: CN202410007480.8A
Authority: CN
Inventors: 白文龙; 李琦; 游兴艳; 武宝珍; 叶永煌; 付成华; 金海族; 吴凯
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2024-01-03
Filing date: 2024-01-03
Publication date: 2024-02-02

Abstract

The application discloses negative pole piece and preparation method, battery and power consumption device thereof, the negative pole piece includes: a negative electrode current collector and a negative electrode active material layer provided on at least one side of the negative electrode current collector, the negative electrode active material layer including dielectric material particles having a volume average particle diameter Dv50 of D ₁ ，D ₁ 400nm to 2000nm, based on the total mass of the anode active material layer, the dielectric materialThe proportion of the particles is 0.1% -10%. Therefore, the dielectric material particles with the particle size and the content are adopted in the negative electrode plate, so that the quick charge performance of the battery can be improved.

Description

Negative electrode plate, preparation method thereof, battery and power utilization device

Technical Field

The application belongs to the field of batteries, and particularly relates to a negative electrode plate, a preparation method thereof, a battery and an electric device.

Background

The secondary battery is widely applied to energy storage power supply systems such as hydraulic power, firepower, wind power, solar power stations and the like, and a plurality of fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like. As the battery application range is becoming wider, the requirements for the performance of the secondary battery are becoming more stringent, such as requiring a fast charge capability. However, the performance of the negative electrode plate in the battery plays a certain limiting role on the quick charge capability, so that the improvement of the performance of the negative electrode plate is urgent.

Disclosure of Invention

In view of the technical problems in the background art, the application provides a negative electrode plate, which aims to improve the quick charge performance of a battery containing the negative electrode plate.

In order to achieve the above object, a first aspect of the present application proposes a negative electrode tab, including:

a negative electrode current collector;

a negative electrode active material layer provided on at least one side of the negative electrode current collector, the negative electrode active material layer including dielectric material particles having a volume average particle diameter Dv50 of D ₁ ，D ₁ From 400nm to 2000nm, the dielectric material particles being present in an amount of 0.1% to 10% based on the total mass of the anode active material layer.

The application at least comprises the following beneficial effects: the dielectric material particles with the particle size and the content are adopted in the negative electrode plate, so that the quick charge performance of the battery can be improved.

In some embodiments, D ₁ 600nm-1000nm. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the dielectric material particles are present in an amount of 0.5% to 3% based on the total mass of the anode active material layer. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the dielectric material particles have a relative dielectric constant of 1000 to 10000, alternatively 1500 to 5000. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the dielectric material particles include at least one of barium titanate, lead titanate, lithium niobate, lead zirconate titanate, lead metaniobate, or lead barium lithium niobate. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the dielectric material particles include dopant ions including trivalent rare earth ions, nb ⁵⁺ 、W ⁵⁺ 、Mo ⁵⁺ 、Al ³⁺ 、Ga ³⁺ 、Cr ³⁺ 、Mn ³⁺ 、Mg ²⁺ 、Si ⁴⁺ Or Ca ²⁺ At least one of them. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the dielectric material particles comprise at least one of trivalent rare earth metal ion doped barium titanate, pentavalent ion doped lead titanate, or pentavalent ion doped lead zirconate titanate, the pentavalent ion comprising Nb ⁵⁺ 、W ⁵⁺ Or Mo (Mo) ⁵⁺ At least one of them. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the trivalent rare earth metal ion comprises Sc ³⁺ 、Y ³⁺ Or Yb ³⁺ At least one of them. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the barium titanate includes a tetragonal crystal form. Thus, the quick charge performance of the battery can be improved.

In some casesIn an embodiment, the dielectric material particles have a BET specific surface area of 0.8m ² /g-7m ² /g, optionally 1.8m ² /g-2m ² And/g. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the anode active material layer includes an anode active material having a volume average particle diameter Dv50 of D ₂ ，D ₁ ≤D ₂ Optionally D ₁ ＜D ₂ . Thus, the quick charge performance of the battery can be improved.

In some embodiments, D ₂ Is 2 μm to 20 μm, optionally 8 μm to 13 μm. Thus, the quick charge performance of the battery can be improved.

In some embodiments, the anode active material layer includes: a first anode active material layer provided on at least one side of the anode current collector; and a second anode active material layer provided on a side of the first anode active material layer remote from the anode current collector, the first anode active material layer and/or the second anode active material layer including the dielectric material particles. Thus, the quick charge performance of the battery can be improved.

In some embodiments, at least a portion of the surface of the anode active material is provided with a coating layer that includes the dielectric material particles. Thus, the quick charge performance and cycle performance of the battery can be improved.

In some embodiments, the negative active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, or a titanate.

In a second aspect of the present application, the present application proposes a method for preparing a negative electrode sheet, comprising:

forming a negative electrode active material layer on at least one side of a negative electrode current collector, the negative electrode active material layer including dielectric material particles having a volume average particle diameter Dv50 of D ₁ ，D ₁ 400nm to 2000nm, the dielectric material particles having a ratio of0.1%-10%。

Therefore, the battery containing the negative electrode plate obtained by the method has excellent quick charge performance.

In a third aspect of the present application, the present application proposes a battery comprising a negative electrode tab according to the first aspect of the present application or a negative electrode tab obtained by a method according to the second aspect of the present application. Thus, the battery has excellent quick-charge performance.

In some embodiments, the battery comprises a lithium ion battery or a sodium ion battery.

In a fourth aspect of the present application, the present application proposes an electrical device comprising a battery according to the third aspect of the present application.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:

fig. 1 is a schematic structural view of a negative electrode tab according to an embodiment of the present application.

Fig. 2 is an XRD pattern of barium titanate according to an embodiment of the present application.

Fig. 3 is a schematic structural view of a negative electrode tab according to still another embodiment of the present application.

Fig. 4 is a schematic view of a battery cell according to an embodiment of the present application.

Fig. 5 is an exploded view of the battery cell of the embodiment of the present application shown in fig. 4.

Fig. 6 is a schematic view of a battery module according to an embodiment of the present application.

Fig. 7 is a schematic view of a battery pack according to an embodiment of the present application.

Fig. 8 is an exploded view of the battery pack of the embodiment of the present application shown in fig. 7.

Fig. 9 is a schematic diagram of an electric device in which a battery according to an embodiment of the present application is used as a power source.

Fig. 10 is a photograph of the negative electrode tab disassembled after the battery of comparative example 4 was cycled.

Fig. 11 is an SEM image of the negative electrode tab disassembled after cycling of the battery of comparative example 4.

Reference numerals illustrate:

10 negative pole pieces; 100 negative electrode current collector; 200 a negative electrode active material layer; 21 a first anode active material layer; 22 a second anode active material layer; 1, a battery cell; 11 a housing; 12 electrode assembly; 13 cover plate; 2 a battery module; 3, a battery pack; 31 upper case; 32 lower box.

Detailed Description

Embodiments of the technical solutions of the present application are described in detail below. The following examples are only for more clearly illustrating the technical solutions of the present application, and thus are only examples, and are not intended to limit the scope of protection of the present application.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

The "range" disclosed herein is defined in terms of lower and upper limits, with a given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise indicated, the numerical range "a-b" represents 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" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.

All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.

All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

Currently, the application of secondary batteries is more widespread in view of the development of market situation. The secondary battery is widely used not only in energy storage power supply systems such as hydraulic power, thermal power, wind power and solar power stations, but also in electric vehicles such as electric bicycles, electric motorcycles and electric automobiles, as well as in a plurality of fields such as military equipment and aerospace.

As secondary batteries are increasingly used in a wide range of applications, the performance of the secondary batteries is increasingly demanding, such as requiring fast charge capability. At present, dielectric material particles are added into a negative electrode plate to improve the quick charge performance of a battery, however, the dielectric material particles are easy to agglomerate in the pulping process due to the small particle size, so that the performance of the dielectric material particles is influenced.

The negative electrode plate disclosed by the embodiment of the application is suitable for lithium ion batteries and sodium ion batteries, and the battery disclosed by the embodiment of the application can be used for electric equipment using the battery as a power supply or various energy storage systems using the battery as an energy storage element. The powered device may include, but is not limited to, a cell phone, tablet, notebook computer, electric toy, electric tool, battery car, electric car, ship, spacecraft, and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

The first aspect of the present application proposes a negative electrode tab, referring to fig. 1, the negative electrode tab 10 includes a negative electrode current collector 100 and a negative electrode active material layer 200, the negative electrode active material layer 200 is disposed on at least one side of the negative electrode current collector 100, the negative electrode active material layer 200 includes dielectric material particles, and a volume average particle diameter Dv50 of the dielectric material particles is D ₁ ，D ₁ From 400nm to 2000nm, the dielectric material particles are present in an amount of 0.1% to 10% based on the total mass of the anode active material layer 200.

In this application, "dielectric material particles" refer to materials that exhibit excellent insulating properties in an electric field, and which can separate charges and store electrical energy without losing charges.

The addition of the dielectric material particles with the particle size and the content into the negative electrode plate 10 can improve the quick charge performance of the battery. The dielectric material particles with the particle size are added into the negative electrode plate 10, so that the agglomeration is not easy to occur due to the large particle size, and other dispersing agents are not required to be additionally added, the performance of the dielectric material particles can be fully exerted, and meanwhile, the content is matched, so that the quick charge performance of the battery can be improved.

The process by which the above dielectric material particles exert their properties is presumed to be as follows: in the charging process of the battery containing the negative electrode plate 10, positive and negative charge centers in the material are separated under the action of an electric field, a counter electric field is generated inside, the electron concentration on the surface of the negative electrode active material is possibly reduced under the action of the counter electric field, and an SEI film (solid electrolyte interface film) formed on the surface of the negative electrode active material is formed by reducing an electrolyte solvent after electrons are obtained on the negative electrode active material, so that the reduction of the electron concentration on the surface of the negative electrode active material can lead to the generation of a thinner SEI film at the three-phase interface of the dielectric material particles, the negative electrode active material and the electrolyte solvent, reduce the loss of active ions and the SEI film impedance, shorten the migration path of the active ions on the SEI film, and further improve the quick charging performance of the battery and reduce the electrolyte consumption. Meanwhile, the counter electric field generated by the dielectric material particles on the surface of the anode active material is negative, so that active ions accumulated on the surface of the anode active material can be attracted to be uniformly distributed, and the risk of dendrite generation caused by the accumulation of the active ions on the local surface of the anode piece is reduced. In addition, the counter electric field generated by the dielectric material particles may reduce the desolvation barrier of the active ions, thereby improving the desolvation rate of the active ions and the diffusion rate of the active ions in the SEI film, and further improving the fast charge performance of the battery.

In some embodiments of the present application, the volume average particle diameter Dv50 of the dielectric material particles is D ₁ ，D ₁ 400nm to 2000nm, for example 400nm to 190 nm,400nm to 180 nm,500nm to 1700nm,600nm to 1100nm, 700nm to 1500nm,800nm to 1400nm,900nm to 1300nm,1000nm to 1200nm,1000nm to 1100nm, etc. In other embodiments of the present application, the volume average particle diameter Dv50 of the dielectric material particles is 600nm to 1000nm.

In some embodiments of the present application, the dielectric material particles may be present in a ratio of 0.1% -10%, such as 0.3% -9.8%,0.5% -9.5%,0.6% -9.2%,0.7% -9%,0.8% -8.8%,0.9% -8.5%,1% -8%,1.1% -7.8%,1.2% -7.5%,1.3% -7.2%,1.5% -7%,1.8% -6.5%,2% -6%,2.5% -5.5%,2.8% -5%,3% -4.5%,3.5% -4%, etc., based on the total mass of the anode active material layer 200. In other embodiments, the dielectric material particles may be present in an amount of 0.5% to 3% based on the total mass of the anode active material layer 200. Thus, the quick charge performance and cycle performance of the battery can be improved.

In the present application, the volume average particle diameter Dv50 of the dielectric material particles refers to the particle diameter corresponding to the cumulative volume distribution percentage reaching 50%, and the method for testing the volume average particle diameter Dv50 of the dielectric material particles in the negative electrode sheet 10 is as follows:

(1) Scraping powder from the negative electrode plate 10, sampling and calcining to 600 ℃, sintering the binder, the negative electrode active substance and the like (mixing the system of the silicon-containing negative electrode active material with sodium hydroxide solution for reaction after sintering), adding water and filtering;

(2) The volume average particle size Dv50 of the dielectric material particles was tested on the filtered material using a laser particle size analyzer (e.g. Malvern Master Size 3000) with reference to standard GB/T19077-2016.

In the application, the mass ratio testing method of the medium material particles in the negative electrode plate 10 comprises the following steps: drying the negative electrode plate 10, scraping and sampling, and carrying out thermal weightlessness test on the sample (the filtered powder is the sample after the system for the silicon-containing negative electrode active material is sintered and then mixed with sodium hydroxide solution for reaction), wherein the test conditions are as follows: the oxygen atmosphere is heated from 25 ℃ to 1000 ℃, the heating rate is 5 degrees/min, and the ordinate of the thermal weight loss curve (thermal weight loss (TG) curve) corresponding to 1000 ℃ is the weight percentage, and the abscissa of the thermal weight loss curve is the temperature), namely the mass ratio of medium material particles in the anode active material layer.

In some embodiments of the present application, the dielectric material particles have a relative dielectric constant of 1000-10000, such as 1000-9500, 1200-9000, 1300-8500, 1500-8000, 1600-7500, 1700-7000, 1800-6500, 1900-6000, 2000-5500, 2100-5000, 2200-4500, 2300-4000, 2400-3500, 2500-3000, 2600-2900, 2700-2800, and the like. Therefore, the application adopts the dielectric material particles meeting the relative dielectric constant in the negative electrode plate 10, so that the quick charge performance of the battery can be further improved.

The process of the dielectric material particles having the above relative permittivity to exert their properties is presumed as follows: the dielectric material particles meeting the relative dielectric constant can form excellent counter electric field effect in the charging process, possibly form a thinner SEI film on the surface of the anode active material, shorten the migration path of active ions in the SEI film, and further improve the quick charge performance of the battery and reduce the consumption of electrolyte. Meanwhile, the counter electric field generated by the dielectric material particles can reduce the desolvation barrier of the active ions, so that the desolvation rate of the active ions and the diffusion rate of the active ions in the SEI film are improved, and the quick charge performance of the battery is further improved. In other embodiments of the present application, the dielectric material particles have a relative dielectric constant of 1500 to 5000.

In the present application, the relative permittivity of the dielectric material particles refers to the relative permittivity at room temperature (25±5 ℃) which has a meaning well known in the art and can be tested using instruments and methods known in the art. For example, the method comprises the steps of firstly scraping powder of a negative electrode plate 10, sampling and calcining to 600 ℃, completing sintering of a binder, a negative electrode active substance and the like (for a silicon-containing negative electrode active material system, mixing and reacting with a sodium hydroxide solution after sintering), adding water, filtering and separating to obtain dielectric material particles, and then preparing the dielectric material particles into a round sample (the sample preparation process comprises the steps of adding 40g of binder (the binder is formed by compounding acrylic acid (PAA) emulsion and alcohol amine plasticizer, the decomposition temperature is less than 300 ℃), fully stirring uniformly, and slowly adding an automatic roller press (the roller press is a pair roller press, and the roller is made of stainless steel, and is subjected to surface polishing treatment); the gap between two pairs of rollers is adjustable within the range of 0.5 mm-2 mm), rolling into raw material ceramic cakes with the thickness of 1mm plus or minus 0.15mm, placing the raw material ceramic cakes under a pressing plate of a sheet punching machine (the pressing plate of the sheet punching machine is round, the size is phi 10 mm-phi 13mm, the pressing plate is stainless steel, and the surface polishing treatment) to punch into 10 thin round ceramic sheets with the diameter of 11 plus or minus 1mm, and (2) discharging glue, namely placing the thin round ceramic sheets obtained in the step (1) on a clean and smooth zirconia or alumina burning plate, placing the thin round ceramic sheets together with the burning plate into a muffle furnace, adopting the heating rate of 0.3 ℃/min, and keeping the temperature after the temperature is raised to 300 DEG C 6h, performing glue discharging; after the front side is subjected to glue discharging, taking out the thin circular ceramic chip, replacing the thin circular ceramic chip with the back side facing upwards, and repeating the operation to obtain back side glue discharging; (3) silver coating: placing the thin-layer round ceramic chip subjected to glue discharging in the step (2) on a clean and flat zirconia or alumina setter plate, and uniformly brushing silver paste on the front surface of the thin-layer round ceramic chip by using a fine brush, wherein the silver paste is high-temperature sintering type conductive silver paste, and the silver paste is brushed for 2-3 times in a unidirectional way, and the thickness is 80-100 mu m; (4) silver burning: firstly, lightly scraping off a silver layer adhered to the side surface of the thin-layer round ceramic chip coated with silver in the step (3) by using a blade, then placing the thin-layer round ceramic chip coated with silver into a muffle furnace together with a burning plate, heating to 800 ℃ at a heating rate of 5 ℃/min, and then preserving heat for 2 hours to burn silver, taking out the thin-layer round ceramic chip and the burning plate after front silver burning is finished, repeating the step (3) and the step (4), and then adopting an LCR tester to test the capacitance C according to the formula: relative dielectric constant ε= (C×d)/(ε) ₀ X a) was calculated. C represents capacitance in Farad (F); d represents the thickness of the sample in cm; a represents the area of the sample in cm ² ；ε ₀ Represents the vacuum dielectric constant, ε ₀ =8.854×10 ^-14 F/cm. In this application, the test conditions may be 1KHz, 1.0V, 25.+ -. 5 ℃. The test standard can be according to GB/T11297.11-2015.

In some embodiments of the present application, the dielectric material particles comprise at least one of barium titanate, lead titanate, lithium niobate, lead zirconate titanate, lead metaniobate, or lead barium lithium niobate. Therefore, the dielectric material particles can further improve the quick charge performance of the battery.

The process by which the dielectric material particles of the above composition exert their properties is presumed to be as follows: the dielectric material particles with the composition can exert excellent counter electric field effect, and can reduce the desolvation barrier of active ions, so that the desolvation rate of the active ions and the diffusion rate of the active ions in the SEI film are improved, and the quick charge performance of the battery is improved.

In some embodiments of the present application, the dielectric material particles include dopant ions including trivalent rare earth ions, nb ⁵⁺ 、W ⁵⁺ 、Mo ⁵⁺ 、Al ³⁺ 、Ga ³⁺ 、Cr ³⁺ 、Mn ³⁺ 、Mg ²⁺ 、Si ⁴⁺ Or Ca ²⁺ At least one of them. Therefore, the dielectric material particles can adjust the relative dielectric constant of the dielectric material particles by doping the ions, so that the quick charge performance of the battery is improved.

The process by which the doped dielectric material particles described above exert their properties is presumed to be as follows: by doping the above ions in the dielectric material particles, the relative dielectric constant of the dielectric material particles can be adjusted, so that the dielectric material particles can exert an excellent counter electric field and reduce the desolvation barrier effect of the active ions, thereby improving the desolvation rate of the active ions and the diffusion rate of the active ions in the SEI film and improving the fast charging performance of the battery.

As an example, the dielectric material particles may include at least one of trivalent rare earth metal ion doped barium titanate, pentavalent ion doped lead titanate, or pentavalent ion doped lead zirconate titanate, e.g., the trivalent rare earth metal ion includes Sc ³⁺ 、Y ³⁺ Or Yb ³⁺ At least one of the pentavalent ions comprising Nb ⁵⁺ 、W ⁵⁺ Or Mo (Mo) ⁵⁺ At least one of them. For example, the dielectric material particles may include Ba _x Ti _y Al _z O ₃ （x+y+z=1）、Ba _a Y _b Ti _c O ₃ （a+b+c=1）、Pb _m Ti _n Nb _p O ₃ (m+n+p=1), and the like.

In some embodiments of the present application, the dielectric material particles are barium titanate, which includes tetragonal crystal forms.

In this application, "tetragonal crystal form" means a crystal structure having a unit cell comprising three axes, two of which have the same length and are at right angles to each other, and the third axis being perpendicular to the other two axes. The tetragonal crystal form of barium titanate can be obtained by XRD test, and figure 2 is XRD diagram of tetragonal crystal form barium titanate, wherein 2 theta position of X-ray diffraction peak is 22 degrees, 31 degrees, 38 degrees, 45 degrees, 56 degrees and 66 degrees.

Thus, the tetragonal barium titanate is adopted as dielectric material particles, which can further improve the desolvation rate of active ions and the diffusion rate of the active ions in the SEI film, further reduce the thickness of the SEI film and improve the cycle performance and the quick charge performance of the secondary battery.

In some embodiments of the present application, the dielectric material particles have a BET specific surface area of 0.8m ² /g-7m ² /g, e.g. 0.9m ² /g-6.5m ² /g，1m ² /g-6m ² /g，1.5m ² /g-5.5m ² /g，1.8m ² /g-5m ² /g，0.8m ² /g-7m ² /g。

Therefore, the combination of the dielectric material particles with the specific surface area range and the anode active material is tighter, the performance of the dielectric material particles is facilitated, the desolvation effect of active ions is possibly further improved, the thickness of the SEI film is reduced, and the cycle performance and the quick charge performance of the battery are further improved. In other embodiments of the present application, the dielectric material particles have a BET specific surface area of 1.8m ² /g-2m ² /g。

In this application, the BET specific surface area of the dielectric material particles is in the meaning well known in the art and can be tested using instruments and methods well known in the art. For example, the negative electrode plate is scraped, sampled and calcined to 600 ℃, the binder, the negative electrode active substance and the like are all sintered (the system of the silicon-containing negative electrode active material is sintered and then mixed with sodium hydroxide solution for reaction), and water is added for filtration. The filtered samples were then tested by the nitrogen adsorption specific surface area analytical test method, calculated by the BET (BrunauerEmmett Teller) method, by reference to GB/T19587-2017, which was performed by a Tri-Star 3020 model specific surface area pore size analytical tester, micromeritics, USA.

As an example, the anode current collector 100 has two surfaces opposing in its own thickness direction, and the anode active material layer 200 is provided on either or both of the two surfaces opposing the anode current collector 100.

In some embodiments of the present application, the negative electrode current collector 100 may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments of the present application, the anode active material layer 200 includes an anode active material having a volume average particle diameter Dv50 of D ₂ ，D ₁ ≤D ₂ . In other embodiments of the present application, the anode active material layer 200 includes an anode active material having a volume average particle diameter Dv50 of D ₂ ，D ₁ ＜D ₂ 。

Therefore, the particle sizes of the anode active material and the dielectric material particles meet the above conditions, and the effect of reducing the desolvation barrier of the dielectric material particles can be fully exerted, so that the desolvation rate of active ions and the diffusion rate of the active ions in the SEI film are improved, and the quick charge performance of the battery is improved; and the negative electrode active material layer 200 can be made to have a high compacted density, improving the battery energy density.

In some embodiments of the present application, the volume average particle diameter Dv50 of the anode active material is D ₂ ，D ₂ From 2 μm to 20 μm, for example from 5 μm to 18 μm, from 8 μm to 15 μm, from 10 μm to 12 μm, etc.

Therefore, the anode active material with the particle size is matched with the dielectric material particles, so that the effect of reducing desolvation barriers of the dielectric material particles can be fully exerted, the desolvation rate of active ions and the diffusion rate of the active ions in an SEI film are improved, and the quick charge performance of a battery is improved; and the negative electrode active material layer 200 can be made to have a high compacted density, improving the battery energy density. At the position ofIn other embodiments of the present application, the volume average particle diameter Dv50 of the anode active material is D ₂ ，D ₂ 8 μm to 13 μm.

In the application, the method for testing the volume average particle size Dv50 of the negative electrode active material in the negative electrode plate comprises the following steps: the method comprises the steps of ablating the surface of a negative electrode plate by flame to remove an adhesive in a surface layer negative electrode active material layer (the flame temperature is 300-500 ℃, the routing speed of the negative electrode plate is 1-30 m/min), scraping powder on the surface layer, sieving the obtained powder, separating the negative electrode active material from a dielectric material and a conductive agent to obtain large-particle-size particles which are the negative electrode active material, and testing the negative electrode active material by a laser particle size analyzer (for example Malvern Master Size 3000) to obtain the volume average particle size Dv50 of the negative electrode active material by referring to the standard GB/T19077-2016.

In some embodiments of the present application, referring to fig. 3, the anode active material layer 200 may include a first anode active material layer 21 and a second anode active material layer 22, the first anode active material layer 21 being disposed on at least one side of the anode current collector 100, the second anode active material layer 22 being disposed on a side of the first anode active material layer 21 remote from the anode current collector 100, the first anode active material layer 21 and/or the second anode active material layer 22 including the dielectric material particles.

In the present application, the "dielectric material particles" may be dispersed in the above-described first anode active material layer 21 or second anode active material layer 22 or both the first anode active material layer 21 and second anode active material layer 22, and the content of each of the dielectric material particles in the first anode active material layer 21 and the second anode active material layer 22 is not limited as long as it satisfies that the ratio of the dielectric material particles is 0.1% to 10% based on the total mass of the anode active material layers.

In some embodiments of the present application, at least a portion of the surface of the anode active material is provided with a coating layer, the coating layer including the dielectric material particles.

Therefore, the dielectric material particles can be in close contact with the anode active material, so that the counter electric field effect of the dielectric material particles can be exerted in the charging process, a thinner SEI film is formed on the surface of the anode plate, the loss of active ions and SEI film impedance are reduced, the migration path of the active ions in the SEI film is shortened, the quick charge performance of the battery can be improved, and the consumption of electrolyte is reduced. Meanwhile, the desolvation barrier of the active ions can be reduced, so that the desolvation rate of the active ions and the diffusion rate of the active ions in the SEI film are improved, and the quick charge performance of the battery is further improved.

In some embodiments of the present application, the anode active material may employ an anode active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, titanates, and the like. The silicon-based material may include at least one of elemental silicon, a silicon oxygen compound, a silicon carbon compound, a silicon nitrogen compound, or a silicon alloy. The tin-based material may include at least one of elemental tin, a tin oxide, or a tin alloy. When the battery is a lithium ion battery, the titanate adopts lithium titanate; when the battery is a sodium ion battery, sodium titanate is used as the titanate. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments of the present application, the anode active material layer 200 may further optionally include a binder. The binder may include at least one of Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), or carboxymethyl chitosan (CMCS).

In some embodiments of the present application, the anode active material layer 200 may further optionally include a conductive agent. The conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

In some embodiments of the present application, the anode active material layer 200 may optionally further include other adjuvants, such as a thickener (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

In yet another aspect, the present application provides a negative electrode active material, at least part of the surface of which is provided with a coating layer comprising particles of a dielectric material, the particles of the dielectric material having a volume average particle diameter Dv50 of D ₁ ，D ₁ 400nm to 2000nm, for example 400nm to 190 nm,400nm to 180 nm,500nm to 1700nm,600nm to 1100nm, 700nm to 1500nm,800nm to 1400nm,900nm to 1300nm,1000nm to 1200nm,1000nm to 1100nm, etc.

Therefore, the dielectric material particles can be in close contact with the anode active material, so that the counter electric field effect of the dielectric material particles can be exerted in the charging process, a thinner SEI film is formed on the surface of the anode plate, the loss of active ions and SEI film impedance are reduced, the migration path of the active ions in the SEI film is shortened, the quick charge performance of the battery can be improved, and the consumption of electrolyte is reduced. Meanwhile, the counter electric field generated by the dielectric material particles on the surface of the negative electrode plate is negative, so that active ions gathered on the surface of the negative electrode plate can be attracted to be uniformly distributed, and the risk of dendrite generation caused by the gathering of the active ions on the local surface of the negative electrode plate is reduced. In addition, the counter electric field generated by the dielectric material particles may reduce the active ion desolvation barrier, thereby improving the desolvation rate of the active ions and the diffusion rate of the active ions in the SEI film, and further improving the fast charge performance of the battery. In other embodiments of the present application, the volume average particle diameter Dv50 of the dielectric material particles is 600nm to 1000nm.

It should be noted that, the relative dielectric constant, the composition and the content of the dielectric material particles in the negative electrode sheet are equivalent to those described above, and will not be described herein.

In a second aspect of the present application, there is provided a method of manufacturing a negative electrode tab, comprising forming a negative electrode active material layer including particles of a dielectric material having a volume average particle diameter Dv50 of D on at least one side of a negative electrode current collector ₁ ，D ₁ From 400nm to 2000nm, the dielectric material particles being present in an amount of 0.1% to 10% based on the total mass of the anode active material layer.

Therefore, the dielectric material particles with the particle size and the content are added into the negative electrode plate 10, so that the quick charge performance of the battery can be improved. The dielectric material particles with the particle size are added into the negative electrode plate 10, so that the agglomeration is not easy to occur due to the large particle size, and other dispersing agents are not required to be additionally added, the performance of the dielectric material particles can be fully exerted, and meanwhile, the content is matched, so that the quick charge performance of the battery can be improved.

In some embodiments of the present application, the negative electrode sheet may be prepared by: dispersing the above components for preparing the negative electrode sheet, such as the negative electrode active material, the dielectric material particles, the conductive agent, the binder and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; and then coating the negative electrode slurry on a negative electrode current collector, and obtaining the negative electrode plate after the procedures of drying, cold pressing and the like.

In a third aspect of the present application, the present application proposes a battery comprising a negative electrode tab according to the first aspect of the present application or a negative electrode tab obtained by a method according to the second aspect of the present application. Thus, the battery has excellent quick charge performance and cycle performance.

In some embodiments of the present application, the battery comprises a lithium ion battery or a sodium ion battery. The battery of the present application includes a battery cell form, a battery module form, and a battery pack form.

Typically, a battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film.

In some embodiments of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one side of the positive electrode current collector, the positive electrode active material layer including the positive electrode active material.

As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.

In some embodiments of the present application, the positive electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (e.g., a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments of the present application, the positive electrode active material layer may further include a positive electrode active material, which may be a positive electrode active material for a battery known in the art.

As an example, when the positive electrode sheet is used for a lithium ion battery, a positive electrode active material known in the art for a lithium ion battery may be used. As an example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (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/ ₃ Mn _1/3 O ₂ (also referred to as NCM) ₃₃₃ ）、LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (also referred to as NCM) ₅₂₃ ）、LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (also referred to as NCM) ₂₁₁ ）、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (also referred to as NCM) ₆₂₂ ）、LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (also referred to as NCM) ₈₁₁ ) Lithium nickel cobalt aluminum oxide (e.g. LiNi _0.8 Co _0.15 Al _0.05 O ₂ ) Or a modified compound thereof, etc. Examples of olivine structured lithium-containing phosphates may include Including but not limited to lithium iron phosphate (e.g., liFePO ₄ (also abbreviated as LFP)), composite material of lithium iron phosphate and carbon, and manganese lithium phosphate (such as LiMnPO) ₄ ) At least one of a composite material of lithium manganese phosphate and carbon, a composite material of lithium manganese iron phosphate or lithium manganese iron phosphate and carbon.

As an example, when the positive electrode sheet is used for a sodium ion battery, a positive electrode active material for a sodium ion battery, which is well known in the art, may be used. As an example, the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a prussian blue analog.

Examples of the layered transition metal oxide include:

Na _1-x Cu _h Fe _k Mn _l M ¹ _m O _2-y wherein M is ¹ Comprises at least one of Li, be, B, mg, al, K, ca, ti, co, ni, zn, ga, sr, Y, nb, mo, in, sn or Ba, 0<x≤0.33，0<h≤0.24，0≤k≤0.32，0<l≤0.68，0≤m<0.1，h+k+l+m＝1，0≤y<0.2；

Na _0.67 Mn _0.7 Ni _z M ² _0.3-z O ₂ Wherein M is ² Comprises at least one of Li, mg, al, ca, ti, fe, cu, zn or Ba, 0<z≤0.1；

Na _a Li _b Ni _c Mn _d Fe _e O ₂ Of which 0.67<a≤1，0<b<0.2，0<c<0.3，0.67<d+e<0.8，b+c+d+e＝1。

Examples of the polyanion compound include:

A ¹ _f M ³ _g (PO ₄ ) _i O _j X ¹ _3-j wherein A is ¹ Comprising H, li, na, K or NH ₄ At least one of M ³ Comprises at least one of Ti, cr, mn, fe, co, ni, V, cu or Zn, X ¹ Is at least one of F, cl or Br, 0<f≤4，0<g≤2，1≤i≤3，0≤j≤2；

Na _n M ⁴ PO ₄ X ² Wherein M is ⁴ Comprises at least one of Mn, fe, co, ni, cu or Zn, X ² Is at least one of F, cl or Br, 0<n≤2；

Na _p M ⁵ _q (SO ₄ ) ₃ Wherein M is ⁵ Comprises at least one of Mn, fe, co, ni, cu or Zn, 0<p≤2，0<q≤2；

Na _s Mn _t Fe _3-t (PO ₄ ) ₂ (P ₂ O ₇ ) Wherein 0 is<s.ltoreq.4, 0.ltoreq.t.ltoreq.3, for example t is 0, 1, 1.5, 2 or 3.

As examples of the above prussian blue analogues, for example, there may be mentioned:

A _u M ⁶ _v [M ⁷ (CN) ₆ ] _w ·xH ₂ o, wherein A comprises H ⁺ 、NH ₄ ⁺ At least one of an alkali metal cation or an alkaline earth metal cation, M ⁶ And M ⁷ Each independently comprises at least one of transition metal cations, 0<u≤2，0<v≤1，0<w≤1，0<x<6. For example A includes H ⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ 、NH ₄ ⁺ 、Rb ⁺ 、Cs ⁺ 、Fr ⁺ 、Be ²⁺ 、Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ Or Ra (R) ²⁺ At least one of M ⁶ And M ⁷ Each independently comprises at least a cation in Ti, V, cr, mn, fe, co, ni, cu, zn, sn or W.

The battery is charged and discharged with the deintercalation and consumption of Li or Na, and the molar content of Li or Na is different when the battery is discharged to different states. In the list of the positive electrode active materials in the application, the molar content of Li or Na is the initial state of the materials, namely the state before charging, and the molar content of Li or Na can be changed after charge and discharge cycles when the positive electrode active materials are applied to a battery system.

In the list of the positive electrode active materials in the present application, the molar content of oxygen is only a theoretical state value, the molar content of oxygen changes due to lattice oxygen release, and the actual molar content of oxygen floats.

In some embodiments of the present application, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, or a fluoroacrylate resin.

In some embodiments of the present application, the binder is present in a mass ratio of 0.5% -3%, such as 0.5%,1%,1.5%,2%,2.5%,3%, etc., based on the total mass of the active material layer.

In some embodiments of the present application, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

In some embodiments of the present application, the conductive agent is present in a mass ratio of 0.8% -4%, for example 0.8%,1%,1.5%,2%,2.5%,3%,3.5%,4%, etc., based on the total mass of the positive electrode active material layer.

In some embodiments of the present application, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.

The type of electrolyte is not particularly limited in this application, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments of the present application, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments of the present application, when the battery is a lithium ion battery, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium difluorosulfonimide, lithium bistrifluoromethanesulfonimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, or lithium tetrafluorooxalato phosphate.

In some embodiments of the present application, when the battery is a sodium ion battery, the electrolyte salt may include at least one of sodium hexafluorophosphate, sodium difluorooxalato borate, sodium tetrafluoroborate, sodium bisoxalato borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis (fluorosulfonyl) imide, sodium trifluoromethylsulfonate, or sodium bis (trifluoromethylsulfonyl) imide.

In some embodiments of the present application, the solvent may include at least one of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylene propylene 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, ethylene glycol dimethyl ether, methyl sulfone, or diethyl sulfone.

In some embodiments of the present application, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability may be used.

In some embodiments, the material of the isolation film may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

In some embodiments, the battery cell may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.

In some embodiments, the exterior packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery cell may also be a pouch, such as a pouch-type pouch. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

The shape of the battery cell is not particularly limited in this application, and may be cylindrical, square, or any other shape. For example, fig. 4 is a square-structured battery cell 1 as one example.

In some embodiments, referring to fig. 5, the outer package may include a housing 11 and a cover 13. The housing 11 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 11 has an opening communicating with the accommodation chamber, and the cover plate 13 can be provided to cover the opening to close the accommodation chamber. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into the electrode assembly 12 through a winding process or a lamination process. The electrode assembly 12 is enclosed in the accommodating chamber. The electrolyte is impregnated in the electrode assembly 12. The number of the electrode assemblies 12 included in the battery cell 1 may be one or more, and one skilled in the art may select according to specific practical requirements.

In some embodiments, the battery cells may be assembled into a battery module, and the number of battery cells included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.

Fig. 6 is a battery module 2 as an example. Referring to fig. 6, in the battery module 2, a plurality of battery cells 1 may be sequentially arranged in the longitudinal direction of the battery module 2. Of course, the arrangement may be performed in any other way. The plurality of battery cells 1 may be further fixed by fasteners.

Alternatively, the battery module 2 may further include a housing having an accommodating space in which the plurality of battery cells 1 are accommodated.

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

Fig. 7 and 8 are battery packs 3 as an example. Referring to fig. 7 and 8, a battery case and a plurality of battery modules 2 disposed in the battery case may be included in the battery pack 3. The battery case includes an upper case 31 and a lower case 32, and the upper case 31 can be covered on the lower case 32 and forms a closed space for accommodating the battery module 2. The plurality of battery modules 2 may be arranged in the battery case in any manner.

In addition, the application also provides an electric device, which comprises the battery provided by the application. The battery cell, the battery module, or the battery pack may be used as a power source of the power device, and may also be used as an energy storage unit of the power device. The power utilization device may include mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric-only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

As the electricity consumption device, a battery cell, a battery module, or a battery pack may be selected according to the use requirements thereof.

Fig. 9 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the high power and high energy density requirements of the power device for the battery, a battery pack or battery module may be employed.

As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a battery cell can be used as a power supply.

Hereinafter, embodiments of the present application are described. The embodiments described below are exemplary only for the purpose of illustrating the present application and are not to be construed as limiting the present application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

1. Preparation of positive electrode plate

The positive electrode active material nickel cobalt lithium manganate (NCM 523 is LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ) The adhesive polyvinylidene fluoride PVDF and the conductive agent acetylene black (Super P) are mixed according to the weight ratio of 98:1:1 mixing, adding N-methyl pyrrolidone (NMP) as solvent, stirring the slurry under vacuum to uniformity to obtain positive electrode slurry, and mixing the obtained positive electrode slurry according to 13.7mg/cm ² The surface density of the aluminum foil is coated on the surfaces of both sides of an aluminum foil with the thickness of 13 mu m by a scraper, then the aluminum foil is dried at 140 ℃, cold-pressed and cut to obtain the positive electrode plate.

2. Preparation of negative electrode plate

Dissolving secondary particles of negative electrode active material artificial graphite, conductive agent acetylene black, composite binder SBR (styrene butadiene rubber), dispersing agent sodium carboxymethylcellulose (CMC-Na) and dielectric material particle barium titanate in solvent deionized water according to the weight ratio of 96:1:1:1:1, stirring and mixing uniformly to prepare negative electrode slurry, uniformly coating the negative electrode slurry on the surfaces of both sides of a 7-mu m negative electrode current collector copper foil, drying, cold pressing and cutting to obtain a negative electrode plate (the thickness of a single-side negative electrode active material layer is 120 mu m).

3. Preparation of electrolyte

In an argon atmosphere glove box (H ₂ O<0.1ppm，O ₂ <0.1 ppm), uniformly mixing organic solvents of Ethylene Carbonate (EC) and ethylmethyl carbonate (EMC) according to a volume ratio of 3:7 to obtain an organic solvent, and mixing LiPF ₆ Dissolving in the solvent, and stirring uniformly to obtain the electrolyte with the concentration of 1 mol/L.

4. Isolation film

A commercially available PP-PE copolymer microporous film (from Zuo Hi-Tech Co., ltd., model 20) having a thickness of 20 μm and an average pore diameter of 80nm was used.

5. Preparation of secondary battery

And sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, so that the isolating film is positioned in the middle of the positive electrode and the negative electrode to play a role in isolation, and winding to obtain the bare cell. And placing the bare cell in an outer package, injecting the electrolyte and packaging to obtain the lithium ion battery.

The lithium ion batteries of examples 2 to 18 and comparative examples 1 to 4 were prepared in the same manner as in example 1, except that the process for preparing the negative electrode tab was different, as shown in table 1.

TABLE 1

The lithium evolution, first week coulombic efficiency, fast charge performance, and cycle performance of the batteries of examples 1-18 and comparative examples 1-4 were characterized and the characterization results are shown in table 3.

(1) And testing lithium precipitation conditions of the negative electrode plate:

Charging the battery to 4.4V under the condition of 4C, standing for 5min, discharging to 2.8V under the condition of 1C, standing for 5min, circulating for 500 circles according to the charging and discharging flow, then disassembling the negative electrode plate, scanning the surface of the disassembled negative electrode plate under the vacuum condition by adopting a back scattering electron diffraction technology (EBSD) (wherein the scanning angle of a scanning electron microscope (Scanning Electron Microscopy, SEM) is 70 degrees), and collecting a lithium-precipitation area signal and a non-lithium-precipitation area signal respectively, wherein the lithium-precipitation area ratio is the intensity of the lithium-precipitation area signal/(the intensity of the lithium-precipitation area signal+the signal intensity of the non-lithium-precipitation area).

(2) First week coulomb efficiency test:

the non-formed secondary battery was charged to 3.4V at 25 ℃ and 0.02C, then to 3.8V at 0.1C, then to 4.4V at 0.5C constant current, then to 0.05C at 4.4V constant voltage, and after 10min of rest, was discharged at 0.5C constant current to a voltage of 2.8V (5 cells per group), and after the first week charge capacity and first week discharge capacity of the secondary battery were obtained, the first coulomb efficiency of the secondary battery was calculated according to the following formula.

First week coulombic efficiency (%) = (first week discharge capacity/first week charge capacity) ×100%.

(3) And (3) quick charge performance test:

charging the battery at 25deg.C constant current to charge cutoff voltage of 4.4V, constant voltage charging to current of 0.05C, standing for 5min, discharging to discharge cutoff voltage of 2.8V at 0.33C constant current, and recording its actual capacity as C ₀ 。

The cells were then sequentially subjected to a temperature of 0.5C ₀ 、1C ₀ 、1.5C ₀ 、2C ₀ 、2.5C ₀ 、3C ₀ 、3.5C ₀ 、4C ₀ 、4.5C ₀ Constant current charging to full battery charge cutoff voltage of 4.4V or 0V negative electrode cutoff potential (based on the first charge), and 1C is needed after each charge is completed ₀ The method comprises the steps of discharging to a full battery discharge cut-off voltage of 2.8V, recording negative electrode potentials corresponding to the conditions of charging to 10%, 20%, 30% … …% SOC (State of Charge) under different charging rates, drawing a multiplying power-negative electrode potential curve under different SOC states, obtaining charging rates corresponding to the conditions of charging to 0V under different SOC states after linear fitting, wherein the charging rates are charging windows under the SOC states and are respectively marked as C10% SOC, C20% SOC, C30% SOC, C40% SOC, C50% SOC, C60% SOC, C70% SOC and C80% SOC, and the charging time T of the battery from 10% SOC to 80% SOC is obtained according to a formula (60/C20% SOC+60/C30% SOC+60/C40% SOC+60/C50% SOC+60/C60% SOC+60/C70% SOC) x 10%. The shorter the charging time T, the more excellent the quick charge performance of the secondary battery is represented.

(4) And (3) testing the cycle performance:

the battery was charged constant current to a cut-off voltage of 4V at 25℃at a 4C rate, then discharged to a cut-off voltage of 2.8V at a 1C rate, and the initial capacity was recorded as C ₀ Then according to the strategy shown in Table 2Slightly charged, discharged at 1C rate, and the discharge capacity C per cycle was recorded _n Up to the capacity retention rate of the battery (capacity retention rate=c _n /C ₀ X 100%) is 80%, the number of cycles is recorded. The more the number of cycles, the better the cycle performance of the secondary battery.

TABLE 2

Fig. 10 is a graph of the battery obtained in comparative example 4 after the battery is cycled (after 300 cycles according to the cycle conditions of the above cycle performance test), and it is clear that the battery obtained in comparative example 4 has obvious lithium dendrites on the surface of the negative electrode after the battery is cycled. Fig. 11 is an SEM image (scanning electron microscope image) of the cell obtained in comparative example 1 at the site of the dendrite dismantling of the negative electrode tab after the cell was cycled, and referring to fig. 11, the surface of the negative electrode active material in the negative electrode tab was obviously lithium dendrite (the rod-like structure circled in the figure is lithium dendrite) after the cell obtained in comparative example 1 was cycled. This indicates that the negative electrode tab of comparative example 4, to which the above-described dielectric material particles were not added, has a risk of generating lithium dendrites.

TABLE 3 Table 3

In conclusion, in examples 1 to 18, compared with comparative examples 1 to 4, the volume average particle diameter Dv50 of the dielectric material particles in the active material layer of the negative electrode tab of the battery of examples 1 to 19 was 400nm to 2000nm, and the ratio of the dielectric material particles was 0.1% to 10% based on the total mass of the negative electrode active material layer, the volume average particle diameter Dv50 of the dielectric material in the active material layer of the negative electrode tab of the battery of comparative example 1 was 112nm, and the mass ratio in the negative electrode active material layer was 1%; the volume average particle diameter Dv50 of the medium material in the active material layer of the negative electrode sheet of the battery of comparative example 2 was 2530nm, and the mass ratio in the negative electrode active material layer was 1%; comparative example 3 battery negative electrode sheet active material layer medium dielectric material volume average particle diameter Dv50 is 820nm, negative electrode active material layer medium dielectric material content is 12%; the active material layer of the negative electrode tab of the battery of comparative example 4 was not added with dielectric material particles, and at the same time, the lithium precipitation area of the negative electrode tab after the battery of examples 1 to 18 was cyclically disassembled was significantly smaller than that of comparative examples 1 to 4, and the charging time of the battery of examples 1 to 18 was also significantly lower than that of comparative examples 1 to 4, and the cycle performance of the battery of examples 1 to 18 was also higher than that of comparative examples 1 to 4.

Therefore, the dielectric material particles (the volume average particle diameter Dv50 of the dielectric material particles is 400-2000 nm, and the proportion of the dielectric material particles is 0.1-10% based on the total mass of the anode active material layer) are adopted in the anode plate, so that the loss of active ions and the lithium separation risk can be reduced, and the cycle performance and the quick charge performance of the battery can be improved.

The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.

Claims

1. A negative electrode tab, comprising:

a negative electrode current collector;

2. The negative electrode tab of claim 1, wherein D ₁ 600nm-1000nm.

3. The negative electrode sheet according to claim 1 or 2, characterized in that the dielectric material particles account for 0.5% -3% based on the total mass of the negative electrode active material layer.

4. The negative electrode tab of claim 1, wherein the dielectric material particles have a relative permittivity of 1000-10000.

5. The negative electrode tab of claim 4, wherein the particles of dielectric material have a relative dielectric constant of 1500-5000.

6. The negative electrode sheet of claim 1, wherein the dielectric material particles comprise at least one of barium titanate, lead titanate, lithium niobate, lead zirconate titanate, lead metaniobate, or lead barium lithium niobate.

7. The negative electrode tab of claim 6 wherein the particles of dielectric material comprise dopant ions comprising trivalent rare earth ions, nb ⁵⁺ 、W ⁵⁺ 、Mo ⁵⁺ 、Al ³⁺ 、Ga ³⁺ 、Cr ³⁺ 、Mn ³⁺ 、Mg ²⁺ 、Si ⁴⁺ Or Ca ²⁺ At least one of them.

8. The negative electrode sheet of claim 7, wherein the dielectric material particles comprise at least one of trivalent rare earth metal ion doped barium titanate, pentavalent ion doped lead titanate, or pentavalent ion doped lead zirconate titanate, the pentavalent ion comprising Nb ⁵⁺ 、W ⁵⁺ Or Mo (Mo) ⁵⁺ At least one of them.

9. The negative electrode sheet according to claim 7 or 8, wherein the trivalent rare earth metal ions comprise Sc ³⁺ 、Y ³⁺ Or Yb ³⁺ At least one of them.

10. The negative electrode sheet according to any one of claims 6 to 8, wherein the barium titanate comprises a tetragonal crystal form.

11. The negative electrode tab of claim 1, wherein the dielectric material particles have a BET specific surface area of 0.8m ² /g-7m ² /g。

12. The anode electrode tab according to claim 1, wherein the anode active material layer comprises an anode active material having a volume average particle diameter Dv50 of D ₂ ，D ₁ ≤D ₂ 。

13. The negative electrode tab of claim 12, wherein D ₂ Is 2 μm to 20 μm.

14. The negative electrode tab of claim 12 or 13, wherein D ₂ 8 μm to 13 μm.

15. The anode electrode tab according to claim 1, wherein the anode active material layer includes:

a first anode active material layer provided on at least one side of the anode current collector;

and a second anode active material layer provided on a side of the first anode active material layer remote from the anode current collector, the first anode active material layer and/or the second anode active material layer including the dielectric material particles.

16. The negative electrode tab of claim 12, wherein at least a portion of the surface of the negative electrode active material is provided with a coating layer, the coating layer comprising the particles of dielectric material.

17. The negative electrode tab of claim 12 or 16, wherein the negative electrode active material comprises at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, or a titanate.

18. A method of making a negative electrode sheet comprising:

forming a negative electrode active material layer on at least one side of a negative electrode current collector, the negative electrode active material layer including dielectric material particles having a volume average particle diameter Dv50 of D ₁ ，D ₁ From 400nm to 2000nm, the dielectric material particles being present in an amount of 0.1% to 10% based on the total mass of the anode active material layer.

19. A battery comprising a negative electrode sheet according to any one of claims 1 to 17 or obtained by the method of claim 18.

20. The battery of claim 19, wherein the battery comprises a lithium ion battery or a sodium ion battery.

21. An electrical device comprising a battery as claimed in claim 19 or 20.