CN116247166A

CN116247166A - Negative electrode plate, preparation method thereof, battery cell, battery and power utilization device

Info

Publication number: CN116247166A
Application number: CN202310499595.9A
Authority: CN
Inventors: 张帆; 石鹏; 赵延杰; 林江辉; 魏冠杰; 孟阵; 宋育倩; 李星
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-05-06
Filing date: 2023-05-06
Publication date: 2023-06-09
Also published as: CN116979026A

Abstract

The embodiment of the application relates to a negative electrode plate and a preparation method thereof, a battery cell, a battery and an electric device, and the preparation method of the negative electrode plate comprises the following steps: providing an organic carbon source solution; adding an organic doping source containing doping elements into the organic carbon source solution, and mixing to form a precursor solution; providing the precursor solution on the surface of the negative electrode current collector, and performing heat treatment on the precursor solution to form a precursor film layer; and etching the precursor film layer by adopting a laser source to obtain a graphene active material layer containing the doping element, wherein the doping element is connected with carbon elements in the graphene active material layer in a chemical bonding mode.

Description

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

Technical Field

The application relates to a negative electrode plate, a preparation method thereof, a battery cell, a battery and an electric device.

Background

The battery monomer has the advantages of reliable working performance, no pollution, no memory effect and the like, and is widely applied. For example, as environmental protection issues become more and more important, new energy automobiles become more and more popular, and the demand for power type battery cells will be on the rise.

As the battery application range increases, the requirements for battery performance become increasingly stringent. The gram capacity of the negative electrode active material, which is an important component of the battery cell, is still further improved.

Disclosure of Invention

The application provides a negative electrode plate, a preparation method thereof, a battery cell, a battery and an electricity utilization device, and the gram capacity of the negative electrode plate can be improved.

In a first aspect, the present application provides a method for preparing a negative electrode tab, including:

providing an organic carbon source solution;

adding an organic doping source containing doping elements into an organic carbon source solution, and mixing to form a precursor solution;

providing a precursor solution on the surface of the negative electrode current collector, and performing heat treatment on the precursor solution to form a precursor film layer;

and etching the precursor film layer by adopting a laser source to obtain a graphene active material layer containing doping elements, wherein the doping elements are connected with carbon elements in the graphene active material layer in a chemical bonding mode.

Therefore, the negative electrode plate obtained by the method of the embodiment of the application comprises the graphene active material layer, the graphene active material layer is stable in structure and is in a three-dimensional structure, the intercalation or deintercalation of active ions such as lithium ions and sodium ions is facilitated, and the multiplying power performance of a battery cell can be improved; and as the doping element is introduced into the graphene active material layer, the gram capacity of the negative electrode plate can be improved, and under the laser etching effect of the laser source, the doping element in the organic doping source and the carbon element in the graphene active material layer can be connected in a chemical bonding mode, so that the gram capacity of the negative electrode plate can be further improved.

In some embodiments, the doping element includes at least one of a first element, a second element, and a third element.

The first element comprises one or more of sulfur element, phosphorus element, silicon element, selenium element and tin element.

And the second element comprises one or more of iron element, cobalt element, nickel element, aluminum element and copper element.

And the third element comprises one or more of boron element, germanium element, titanium element and magnesium element.

Thus, the first element of the embodiments of the present application has electrochemical activity, and the element having electrochemical activity can increase the energy density of the battery cell. The second element may include an element having conductivity, which can reduce the internal resistance of the electrode sheet and can improve the rate capability of the battery cell. The third element may occupy the position of a carbon atom in the graphene, forming an electron transfer or an electron hole, so that the graphene has special semiconductor characteristics; and the doped elements can also produce lattice defects, widen the transmission channel of active ions, improve the wettability of the graphene active material layer and the like, thereby further improving the performance of the negative electrode plate.

In some embodiments, the doping element comprises elemental sulfur and the organic doping source comprises one or more of thiourea, methionine, thioglycolic acid, 2-mercaptoethanol, thiobenzoic acid, diphenyl sulfoxide, cysteine, and benzenesulfonic acid.

In some embodiments, the doping element comprises a phosphorus element and the organic doping source comprises one or more of phosphorous acid, hydrocarbyl phosphonite, hydrocarbyl phosphinite, phosphite, ethyl hypophosphite, and hydrocarbyl phosphonite.

In some embodiments, the doping element comprises elemental silicon and the organic doping source comprises one or more of trimethylsilanol, triethylsilanol, diphenylmethylsilane, hexamethyleneoxy disilane, trimethylphenylsilane, and tetraethylorthosilicate.

In some embodiments, the doping element comprises elemental tin and the organic doping source comprises one or more of monobutyl tin, dibutyl tin, tributyl tin oxide, triphenyl tin, dioctyl tin.

In some embodiments, the doping element comprises a nickel element and the organic doping source comprises one or more of nickel oxalate, nickel oleate, nickel propionate, nickel butyrate, nickel octoate, nickel lactate.

In some embodiments, the doping element comprises elemental copper and the organic doping source comprises one or more of copper acetate, copper fatty acid, copper naphthenate.

In some embodiments, the doping element comprises boron and the organic doping source comprises one or more of phenylboronic acid, diphenylboronic acid, triphenylboron, trimethoxyboroxine.

In some embodiments, the doping element comprises elemental selenium and the organic doping source comprises one or more of dimethyl selenium, diethyl diselenide.

In some embodiments, the doping element comprises elemental germanium and the organic doping source comprises one or more of tetraethylgermanium, methyl germanium mercaptide, butyl germanium mercaptide, octyl germanium mercaptide.

In some embodiments, the doping element comprises elemental iron and the organic doping source comprises one or more of ferrous lactate, ferric citrate, ferric glycinate.

In some embodiments, the doping element comprises elemental cobalt and the organic doping source comprises one or more of cobalt oxalate, cobalt acetate.

In some embodiments, the doping element comprises elemental titanium and the organic doping source comprises one or more of orthotitanate, butyl titanate.

In some embodiments, the doping element comprises an aluminum element and the organic doping source comprises one or more of triethylaluminum, triisobutylaluminum, diethylaluminum chloride.

In some embodiments, the doping element comprises magnesium, and the organic doping source comprises one or more of magnesium glycinate, magnesium citrate, magnesium lactate.

In some embodiments, the mass percent of the organic doping source is 0.2wt% to 20wt%, based on the total mass of the precursor solution. When the mass percentage of the organic doping source is in the range, the gram capacity and the electrochemical performance of the cathode pole piece can be further improved.

In some embodiments, the precursor solution has a thickness of 40 μm to 150 μm. The precursor solution meeting the thickness range can improve the occupied space of the active material layer, so that the energy density of the battery unit is improved.

In some embodiments, the step of thermally treating the precursor solution to form a precursor film layer includes:

first heat treating the precursor solution to remove at least a portion of the solvent in the precursor solution and to retain the solute in the precursor solution;

the second heat treats the solute in the precursor solution and provides an external force to the solute to form a precursor film layer.

In some embodiments, the precursor film layer has a thickness of 30 μm to 120 μm. The precursor solution meeting the thickness range can improve the occupied space of the active material layer, so that the energy density of the battery unit is improved.

In some embodiments, the step of providing an organic carbon source solution comprises: and dissolving an organic carbon source in a solvent to obtain an organic carbon source solution, wherein the organic carbon source comprises one or more of polyamic acid, polyvinylpyrrolidone, isobutyl vinyl ether, polyvinyl acetate, cellulose ester compounds, polyalkenol compounds, polyolefin compounds and polysaccharide compounds.

In some embodiments, the cellulose ester compound comprises one or more of cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate.

In some embodiments, the polyalkenyl alcohol compound includes polyvinyl alcohol and/or polypropylene alcohol.

In some embodiments, the polyolefin-based compound comprises polypropylene and/or polystyrene.

In some embodiments, the polysaccharide compound includes one or more of cellulose, chitosan, and chitin.

In some embodiments, the current collector comprises a metal substrate.

In some embodiments, a current collector includes an organic polymer layer and a metal layer disposed on at least one surface of the organic polymer layer, wherein a precursor solution is provided to a surface of the metal layer.

In some embodiments, the laser source comprises one or more of a carbon dioxide laser source, a diode laser source, an argon ion laser source, a nitrogen laser source, a red laser source, a blue laser source, and a femtosecond laser source.

In some embodiments, the laser source comprises a carbon dioxide laser source.

In some embodiments, the output power of the carbon dioxide laser source is 10W to 30W. When the output power of the carbon dioxide laser source is in the above range, the doping element in the organic doping source can be linked with the carbon element in the graphene active material layer in a chemically bonded form at this output power.

In some embodiments, the carbon dioxide laser source meets at least one of the following conditions:

(1) The laser wavelength of the carbon dioxide laser source is 2-50 μm;

(2) The pulse width of the carbon dioxide laser source is 10 mu s to 30 mu s;

(3) The number of pulses per inch of the carbon dioxide laser source is 800 to 1200;

(4) The beam radius of the carbon dioxide laser source is 50 μm to 150 μm;

(5) The scanning speed of the carbon dioxide laser source is 2cm/s to 5cm/s;

(6) The dimension between the carbon dioxide laser source and the precursor film layer is 2mm to 4mm along the thickness direction of the negative electrode current collector;

(7) The laser intensity of the surface of the precursor film facing the carbon dioxide laser source is in the range of 10J/cm ² To 30J/cm ² 。

Thus, when at least one of the above conditions is satisfied, the performance of the prepared graphene active material layer can be further improved, for example, the uniformity of the performance of the entire graphene active material layer can be improved.

In a second aspect, the application provides a negative electrode piece, the negative electrode piece comprises a negative electrode current collector and a graphene active material layer, the graphene active material layer is located on at least one surface of the negative electrode current collector, the graphene active material layer is formed by etching a laser source, and the graphene active material layer comprises a doping element and a carbon element which are connected in a chemical bonding mode.

In some embodiments, the mass percent of doping element is 0.1wt% to 10wt%, based on the total mass of the graphene active material layer. When the mass percentage of the doping elements is in the range, the gram capacity and the electrochemical performance of the negative electrode plate can be further improved.

In some embodiments, the graphene active material layer has a thickness of 30 μm to 120 μm. The graphene active material layer satisfying the above thickness range can enable the battery cell energy density to be improved.

In some embodiments, the negative electrode sheet uses lithium metal as a counter electrode, and in a charge-discharge curve obtained by testing in the range of 0.005V to 2.5V, the charge gram capacity of 0.005V to 2.5V is 400mAh/g to 480mAh/g; optionally 433mAh/g to 466mAh/g.

In some embodiments, the graphene active material layer has a pore-like structure that facilitates migration of active ions.

In some embodiments, the pore structure has a pore size of 1nm to 80nm. The holes of the porous structure can be nano holes, so that the structural strength of the graphene sheet is improved, and the transmission of active ions is facilitated.

In some embodiments, the graphene active material layer has a porosity of 5% to 30%. When the porosity of the graphene active material layer is in the range, the tap density of the negative electrode plate can be improved, and the energy density of the battery cell can be improved.

In some embodiments, the graphene active material layer has a specific surface area of 30m ² /g to 500m ² And/g. When the specific surface area of the graphene active material layer is in the above range, the cohesiveness of the graphene active material layer can be improved, and the tap density of the negative electrode plate can be improved, so that the energy density of the battery cell can be improved.

In a third aspect, the present application proposes a battery cell comprising a negative electrode tab according to any one of the embodiments of the second aspect of the present application.

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

In a fifth aspect, the present application proposes an electrical device comprising a battery as described in the fourth aspect of the present application.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and that other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic flow chart of preparing a negative electrode sheet according to an embodiment of the present application.

Fig. 2 is a schematic view of a battery cell according to an embodiment of the present application.

Fig. 3 is an exploded view of the battery cell shown in fig. 2.

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

Fig. 5 is a schematic view of a battery pack according to an embodiment of the present application.

Fig. 6 is an exploded view of the battery pack shown in fig. 5.

Fig. 7 is a schematic view of an electrical device including a battery cell according to an embodiment of the present application as a power source.

Fig. 8 is an X-ray diffraction XRD pattern of the laser etching to form a graphene active material layer in example 1 of the present application.

Fig. 9 is a Raman spectrum Raman diagram of a graphene active material layer formed by laser etching in example 1 of the present application.

Fig. 10 is a TEM image of a graphene active material layer formed by laser etching in example 1 of the present application.

Fig. 11 is a SEM image of a graphene active material layer formed by laser etching in example 1 of the present application.

Fig. 12 is an EDX elemental analysis diagram of a graphene active material layer formed by laser etching in example 1 of the present application.

Fig. 13 is a schematic diagram of charge and discharge curves (0.1C cycle 100) of the lithium ion battery of example 1 of the present application.

Detailed Description

Hereinafter, embodiments of a negative electrode tab, a method of manufacturing the same, a battery cell, a battery, and an electric device of the present application are specifically disclosed with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

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.

Reference herein to "comprising" and "including" means open ended, as well as closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.

The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).

The battery cell comprises a positive pole piece, a negative pole piece and an isolating film, wherein the isolating film is positioned between the positive pole piece and the negative pole piece to isolate the positive pole piece and the negative pole piece, and active ions migrate between the positive pole piece and the negative pole piece through electrolyte, so that the charge and discharge of the battery cell are realized.

The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material, wherein the negative electrode active material is usually made of graphite material according to LiC between graphite layers ₆ The theoretical gram capacity of the lithium storage mechanism is about 372 mAh/g, and the rate capability is limited by lithium diffusion between graphite layers. With the development of technology, the capacity of the graphite cathode is gradually close to the theoretical value, and the lifting space is very limited. Therefore, as the requirements of the new energy field on the energy and power performance of the battery are continuously improved, the pure graphite cathode material has been proved to be the best of the forepart. Graphene has excellent optical, electrical, mechanical and other characteristics, and has important application prospects in the field of new energy. However, when graphene is prepared as a negative electrode active material, the gram capacity is difficult to further increase, and the prepared graphene is easy to cause problems of interlayer accumulation and the like, and has poor structural stability.

In view of the above problems, the embodiments of the present application provide a method for preparing a negative electrode sheet, where an organic carbon source solution and an organic doping source are disposed on a surface of a negative electrode current collector, and etching treatment is performed on the organic carbon source solution and the organic doping source by a laser source, so that a graphene active material layer combined on the negative electrode current collector can be obtained, and the graphene active material layer has a relatively stable structure and is in a three-dimensional structure, and the structure is relatively stable, thereby being beneficial to intercalation or deintercalation of active ions such as lithium ions and sodium ions, and being capable of improving the rate capability of a battery cell; and the organic doping source can enable the doping element in the organic doping source and the carbon element in the graphene active material layer to be connected in a chemical bonding mode under the laser etching effect of the laser source, and the doping element can further improve the gram capacity of the negative electrode plate.

Preparation method of negative electrode plate

In a first aspect, an embodiment of the present application provides a method for preparing a negative electrode sheet, where the method includes:

step S100, providing an organic carbon source solution;

step S200, adding an organic doping source containing doping elements into an organic carbon source solution, and mixing to form a precursor solution;

Step S300, providing a precursor solution on the surface of the negative electrode current collector, and performing heat treatment on the precursor solution to form a precursor film layer;

and step S400, etching the precursor film layer by using a laser source to obtain a graphene active material layer containing doping elements, wherein the doping elements are connected with carbon elements in the graphene active material layer in a chemical bonding mode.

According to the negative electrode piece obtained by the method, the negative electrode piece comprises the graphene active material layer, the graphene active material layer is stable in structure and is in a three-dimensional structure, so that the intercalation or deintercalation of active ions such as lithium ions and sodium ions is facilitated, and the multiplying power performance of a battery monomer can be improved; and as the doping element is introduced into the graphene active material layer, the gram capacity of the negative electrode plate can be improved, and under the laser etching effect of the laser source, the doping element in the organic doping source and the carbon element in the graphene active material layer can be connected in a chemical bonding mode, so that the gram capacity of the negative electrode plate can be further improved.

In the embodiments herein, chemical bonding refers to the connection between two elements in the form of a chemical bond. The doping element is a non-carbon element, and the gram capacity of the negative electrode plate can be further improved by introducing the doping element.

In step S100, the organic carbon source solution includes an organic carbon source and a solvent, and the organic carbon source is dissolved in the solvent to obtain the organic carbon source solution. The organic carbon source is a solute of an organic carbon source solution, and the solvent is a solvent capable of dissolving the organic carbon source. In the present embodiment, dissolution means that a solute and a solvent can be mixed to form a phase in a uniform state, and in the case where the solute can be dissolved in the solvent, the solubility of the solute in the solvent is generally 10g or more; i.e., the organic carbon source has a solubility in the solvent of greater than or equal to 10g. The organic carbon source is dissolved in the solvent, so that the organic carbon source is uniformly distributed in the solvent, and the subsequent uniform film formation is facilitated. The organic carbon source solution is favorable for being uniformly dissolved in the solvent and is favorable for forming a light and thin graphene layer structure because the organic carbon source solution only comprises the organic carbon source as a solute. Of course, the organic carbon source solution in embodiments of the present application may also include other materials that facilitate film formation.

Illustratively, an organic carbon source is added to the solvent and stirred for 20min to 60min to obtain an organic carbon source solution.

In some embodiments, the organic carbon source is an organic compound, which may include an organic high molecular compound (e.g., a polymer) or an organic low molecular compound (e.g., a small molecular compound), and the organic compound is more favorable for forming a graphene active material layer with uniform performance and thickness on the negative electrode current collector.

In some embodiments, the organic carbon source comprises one or more of polyamic acid, polyvinylpyrrolidone, isobutyl vinyl ether, polyvinyl acetate, cellulose esters, polyols, polyolefins, and polysaccharides. The film prepared by the organic carbon source is compact and uniform and has high mechanical strength.

As some examples, cellulose ester compounds include one or more of cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate.

As some examples, the polyalkenyl alcohol compound includes polyvinyl alcohol and/or polypropylene alcohol.

As some examples, the polyolefin-based compound includes polypropylene and/or polystyrene.

As some examples, the polysaccharide compound includes one or more of cellulose, chitosan, and chitin.

In the embodiments of the present application, the kind of the solvent is not particularly limited, and the solvent may be capable of dissolving the corresponding organic compound, and in some embodiments, the solvent may include one or more of water, an alcohol solvent, a ketone solvent, N-methylpyrrolidone, N-dimethylformamide, methylene chloride, chloroform, methyl acetate, and acetic acid.

For example, the organic carbon source solution may include a polyamic acid solution whose solute is polyamic acid and whose solvent is N-methylpyrrolidone.

Illustratively, the organic carbon source solution may include a polypropylene solution whose solute is polypropylene and whose solvent is acetone.

Illustratively, the organic carbon source solution may include a polyvinyl alcohol solution whose solute is polyvinyl alcohol and whose solvent is water.

Illustratively, the organic carbon source solution may include a solution of a polypropylene alcohol whose solute is polypropylene alcohol and whose solvent is ethanol.

Illustratively, the organic carbon source solution may include a polyvinylpyrrolidone solution whose solute is polyvinylpyrrolidone and whose solvent is water.

Illustratively, the organic carbon source solution may include a polystyrene solution whose solute is polystyrene and whose solvent is a mixture of N, N-dimethylformamide and chloroform.

Illustratively, the organic carbon source solution may include an isobutyl vinyl ether solution, the solute of which is isobutyl vinyl ether, and the solvent of which is diethyl ether.

Illustratively, the organic carbon source solution may include a cellulose acetate solution whose solute is cellulose acetate and whose solvent includes at least one of dichloromethane and methyl acetate.

Illustratively, the organic carbon source solution may include a cellulose acetate butyrate solution, the solute of which is cellulose acetate butyrate, and the solvent of which includes at least one of dichloromethane and methyl acetate.

Illustratively, the organic carbon source solution may include a cellulose acetate propionate solution whose solute is cellulose acetate propionate and whose solvent includes at least one of methylene chloride and methyl acetate.

Illustratively, the organic carbon source solution may include a polyvinyl acetate solution whose solute is polyvinyl acetate and whose solvent is ethanol.

Illustratively, the organic carbon source solution may include a cellulose acetate solution, the solute of which is cellulose, and the solvent of which is acetic acid.

Illustratively, the organic carbon source solution may include a chitosan acetic acid solution, the solute of which is chitosan, and the solvent of which is acetic acid.

Illustratively, the organic carbon source solution may include a chitin acetic acid solution, the solute of which is chitin, and the solvent of which is acetic acid.

In step S200, an organic doping source is added to the organic carbon source solution and mixed to form a precursor solution.

Doping elements can be introduced into the precursor solution by adding an organic doping source, so that the electrochemical performance of the graphene active material layer is improved. The precursor solution may be considered to be formed by mixing an organic doping source and an organic carbon source solution, for example, the organic doping source may be dissolved or dispersed in the organic carbon source solution, and chemical reaction may not occur between the organic doping source and the organic carbon source solution.

The first element may include an element having electrochemical activity capable of increasing the energy density of the battery cell. For example, the first element includes one or more of elemental sulfur, elemental phosphorus, elemental silicon, elemental selenium, and elemental tin. The substance formed by etching the organic doping source containing the first element may also be electrochemically active.

The second element may include an element having conductivity, which can reduce the internal resistance of the electrode sheet and can improve the rate capability of the battery cell. For example, the second element may include one or more of an iron element, a cobalt element, a nickel element, an aluminum element, and a copper element. The material formed after etching of the organic dopant source comprising the second element may also be electrically conductive.

The third element may include one or more of boron element, germanium element, titanium element, and magnesium element. The doping elements may occupy the positions of carbon atoms in the graphene to form electron transfer or electron holes, so that the graphene has special semiconductor characteristics; and the doped elements can also produce lattice defects, widen the transmission channel of active ions, improve the wettability of the graphene active material layer and the like, thereby further improving the performance of the negative electrode plate.

In some embodiments, the organic doping source of the sulfur-containing element may include one or more of thiourea, methionine, thioglycolic acid, 2-mercaptoethanol, thiobenzoic acid, diphenyl sulfoxide, cysteine, and benzenesulfonic acid.

In some embodiments, the organic doping source of the phosphorus-containing element may include one or more of phosphorous acid, hydrocarbyl phosphonite, hydrocarbyl phosphinite, phosphite, ethyl hypophosphite, and hydrocarbyl phosphonite.

In some embodiments, the organic doping source of the silicon-containing element may include one or more of trimethylsilanol, triethylsilanol, diphenylmethylsilane, hexamethyleneoxy disilane, trimethylphenylsilane, and tetraethylorthosilicate.

In some embodiments, the organic doping source of tin-containing elements may include one or more of monobutyl tin, dibutyl tin, tributyl tin oxide, triphenyl tin, dioctyl tin.

In some embodiments, the organic doping source comprising the nickel element may include one or more of nickel oxalate, nickel oleate, nickel propionate, nickel butyrate, nickel octoate, nickel lactate.

In some embodiments, the organic doping source of the copper-containing element may include one or more of copper acetate, copper fatty acid, copper naphthenate.

In some embodiments, the organic doping source of the boron-containing element may include one or more of phenylboronic acid, diphenylboronic acid, triphenylboron, trimethoxyboroxine.

In some embodiments, the organic doping source comprising elemental selenium may include one or more of dimethyl selenium, diethyl diselenide.

In some embodiments, the organic doping source comprising elemental germanium may include one or more of tetraethylgermanium, methyl germanium thiolate, butyl germanium thiolate, octyl germanium thiolate.

In some embodiments, the organic doping source of the iron-containing element may include one or more of ferrous lactate, ferric citrate, ferric glycinate.

In some embodiments, the organic doping source containing cobalt element may include one or more of cobalt oxalate, cobalt acetate.

In some embodiments, the organic doping source of the titanium-containing element may include one or more of orthotitanate, butyl titanate.

In some embodiments, the organic dopant source comprising an aluminum element may include one or more of triethylaluminum, triisobutylaluminum, diethylaluminum chloride.

In some embodiments, the organic doping source containing magnesium element may include one or more of magnesium glycinate, magnesium citrate, magnesium lactate.

Illustratively, the organic dopant source may be present in a mass percent of 0.2wt%, 0.3wt%, 0.5 wt%, 0.8 wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, or a range of any two of the foregoing values.

Illustratively, the mass percent of doping element may be 0.1wt%, 0.2wt%, 0.3wt%, 0.5 wt%, 0.8 wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, or a range of any two values above.

In step S300, a precursor solution is provided on the surface of the negative electrode current collector, and the precursor solution may be provided on the surface of the negative electrode current collector by coating or the like, and the precursor solution is prepared into a precursor film layer by removing at least part of the solvent in the precursor solution and performing heat treatment on the precursor solution.

As shown in fig. 1, the precursor solution may be coated on the surface of the negative electrode current collector by using a doctor blade, and specifically, the specific steps of using the doctor blade include:

step S310, coating a precursor solution on the surface of the negative electrode current collector;

step S320, adjusting the distance between the doctor blade and the surface of the negative electrode current collector, and adjusting the thickness of the precursor solution.

Coating the precursor solution on the surface of the negative electrode current collector, wherein the thickness of the precursor solution coated on the surface of the negative electrode current collector is nearly uniform due to certain fluidity of the precursor solution; to further improve thickness uniformity, a portion of the precursor solution may be removed; for example, a doctor blade is used to remove a portion of the precursor solution, and during the removal process, the distance between the doctor blade and the surface of the negative electrode current collector is maintained substantially constant along the thickness direction of the negative electrode current collector, and the doctor blade is moved in a first direction to remove a portion of the precursor solution. In the embodiment of the present application, the first direction may be perpendicular to the thickness direction of the negative electrode current collector, and the first direction may be a length direction or a width direction of the negative electrode current collector.

In some embodiments, the precursor solution has a thickness of 40 μm to 150 μm. The precursor solution meeting the thickness range can improve the occupied space of the active material layer, so that the energy density of the battery unit is improved. In the embodiment of the present application, the thickness of the precursor solution is the thickness adjusted by the doctor blade.

Illustratively, the precursor solution may have a thickness of 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 150 μm, or a range of any two of the numerical compositions described above.

step S330, first heat treatment of the precursor solution to remove at least part of the solvent in the precursor solution and retain the solute in the precursor solution;

in step S340, the solute in the precursor solution is subjected to a second heat treatment, and an external force is applied to the solute to form a precursor film layer.

The precursor solution is subjected to a heat treatment of a plurality of processes, including, for example, a first heat treatment and a second heat treatment; specifically, the precursor solution is subjected to a first heat treatment at a first temperature, so that at least part of solvent in the precursor solution can be removed, and solute (comprising an organic carbon source and an organic doping source) in the precursor solution is reserved, so that the solute of the precursor solution can be formed into a film preliminarily; in other words, the temperature range of the first temperature should be greater than or equal to the boiling point of the solvent. The first temperature may be, for example, 50 ℃ to 100 ℃. For example, the precursor solution is placed in a vacuum oven and dried in vacuo at 50 ℃ to 100 ℃ for 2 hours.

After the precursor solution is subjected to the first heat treatment, the remaining main components are solutes, the solutes are subjected to the second heat treatment at the second temperature, and external acting force is provided on the solutes of the precursor solution, which can be understood as that the solutes of the precursor solution are subjected to the hot pressing treatment to form the precursor film layer. The temperature range of the second temperature should be greater than or equal to the melting point of the solute of the precursor solution. Illustratively, the second temperature may be 150 ℃ to 350 ℃. For example, the solute of the precursor solution is hot pressed into a film at 200 ℃ under a pressure of 0.5MPa to 5.0 MPa.

According to the embodiment of the application, the precursor solution is subjected to heat treatment and the like, the solvent in the precursor solution is volatilized gradually, the solute in the precursor solution is uniformly distributed on the surface of the negative electrode current collector, the precursor film layer with uniform thickness is formed on the surface of the negative electrode current collector, the thermal expansion coefficient of the precursor film layer is relatively low, and the pinhole form is not easy to exist.

In some embodiments, the precursor film layer has a thickness of 30 μm to 120 μm. When the thickness of the precursor film layer is in the above range, more space can be given to the active material layer, so that the energy density of the battery cell is improved.

Illustratively, the precursor film layer may have a thickness of 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, or a range of any two values of the foregoing.

The precursor solution of the embodiments of the present application may be applied by single-sided coating or double-sided coating.

In some embodiments, a single-sided coating is employed, i.e., a precursor solution is provided on one surface of the negative electrode current collector. In other embodiments, in the form of double-sided coating, the anode current collector includes two surfaces opposite to each other in the thickness direction thereof, a precursor solution is supplied to one of the two surfaces of the anode current collector, the precursor solution is heat-treated to form a precursor film layer, and then the precursor solution is supplied to the other surface of the anode current collector, and the precursor solution is heat-treated to form the precursor film layer.

In the present embodiment, the thickness of the precursor film refers to the thickness of the precursor film on one surface of the negative electrode current collector.

The method of the embodiment is suitable for preparing the positive electrode current collector or the negative electrode current collector.

In some embodiments, the negative electrode current collector may include a metal substrate, such as a metal foil, and the negative electrode current collector may also include a composite current collector. As an example of the metal foil, copper foil may be used. The composite current collector may include an organic polymer layer and a metal layer disposed on at least one surface of the organic polymer layer. The metal layer may be disposed on one surface of the organic polymer layer, or on both surfaces.

As an example, the host material of the metal layer may include at least one of copper, copper alloy, nickel alloy, titanium alloy, silver, and silver alloy. As an example, the organic polymer layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and Polyethylene (PE). In the case where the negative electrode current collector is a composite current collector, the precursor solution may be disposed on the surface of the metal layer.

In step S400, a laser source is used to etch the precursor film layer to obtain a graphene active material layer.

The precursor film layer is subjected to morphological change under the etching of high-energy laser spots, and the organic carbon source in the precursor film layer forms a graphene framework structure, so that the graphene framework structure is uniform in thickness due to the fact that the graphene framework structure is derived from the organic carbon source (organic material), and the uniformity and consistency of the graphene active material layer are good. The graphene active material layers are in a three-dimensional structure, the distance between the graphene sheets is relatively large, the space and the specific surface area are relatively large, the transmission of active ions is facilitated, and the multiplying power performance of the battery monomer is improved.

The graphene also has excellent conductivity, can effectively reduce the internal resistance of the battery monomer, reduce ohmic polarization and improve the multiplying power performance of the battery monomer.

Specifically, graphene is formed by disordered loose aggregation of carbon atoms in a single-sheet layer and single-atom thickness, and the structure is beneficial to insertion of active ions such as lithium ions, so that the graphene has high specific capacity; the graphene material has a special structure with a two-dimensional high specific surface area and excellent electron transmission capacity, can reduce lithium ion movement resistance, and further can obviously optimize the reversibility of battery monomer circulation, so that the graphene has a good ion transmission channel; the graphene skeleton structure has higher thermal conductivity and structural stability, so that energy accumulation generated by long-term operation of the battery monomer can be evacuated in time, and the problem of temperature rise in the battery is further relieved, thereby being beneficial to maintaining the long-term cycle performance of the battery; the interlayer spacing of the graphene material is larger, the lamellar dimension is far smaller than that of bulk graphite, the diffusion distance of lithium ions between graphene lamellar layers is shortened by the structure, the rapid intercalation and deintercalation of lithium ions are facilitated, and the multiplying power performance of the lithium ion battery is remarkably improved.

The organic doping source and the organic carbon source in the precursor film layer are etched by laser at the same time, and doping elements in the organic doping source can be connected with carbon atoms in a chemical bonding mode under the high-energy etching of the organic doping source, so that the electrochemical performance of the anode plate can be further improved; the preparation method can enable graphene sheets to be not easy to accumulate, and can improve first coulomb efficiency and the like.

In some embodiments, the laser source may include one or more of a carbon dioxide laser source, a diode laser source, an argon ion laser source, a nitrogen laser source, a red laser source, a blue laser source, and a femtosecond laser source. Alternatively, the laser source comprises a carbon dioxide laser source. Scanning the laser source according to a preset path until the whole precursor film layer is scanned; for example, the laser source may perform a linear scan along the length direction of the negative current collector until the scanning is completed for the entire precursor film layer; of course, the laser source may perform linear scanning or the like along the width direction of the negative electrode current collector.

Illustratively, the output power of the carbon dioxide laser source may be 10W, 12W, 13W, 14W, 15W, 16W, 18W, 20W, 22W, 23W, 25W, 26W, 28W, 30W or a range of any two values.

The performance of the prepared graphene active material layer can be further improved when at least one of the following conditions is met, for example, the uniformity of the performance of the whole graphene active material layer can be improved.

In some embodiments, the laser wavelength of the carbon dioxide laser source is 2 μm to 50 μm.

In some embodiments, the pulse width of the carbon dioxide laser source is 10 μs to 30 μs.

In some embodiments, the number of pulses per inch of the carbon dioxide laser source is 800 to 1200.

In some embodiments, the beam radius of the carbon dioxide laser source is 50 μm to 150 μm.

In some embodiments, the scanning speed of the carbon dioxide laser source is from 2cm/s to 5cm/s.

In some embodiments, the dimension between the carbon dioxide laser source and the precursor film layer is 2mm to 4mm in the thickness direction of the negative electrode current collector.

In some embodiments, the laser intensity of the surface of the precursor film facing the carbon dioxide laser source is in the range of 10J/cm ² To 30J/cm ² . When the laser intensity range of the carbon dioxide laser source is within the above range, the doping element in the organic doping source can be linked with the carbon element in the graphene active material layer in a chemical bonding form at this output power. Illustratively, the laser intensity of the surface of the carbon dioxide laser source at the precursor film level is in the range of 10J/cm ² 、12 J/cm ² 、14 J/cm ² 、15 J/cm ² 、16 J/cm ² 、18 J/cm ² 、20 J/cm ² 、21 J/cm ² 、22 J/cm ² 、23 J/cm ² 、25 J/cm ² 、26 J/cm ² 、27 J/cm ² 、28 J/cm ² 、29 J/cm ² 、30 J/cm ² Or a range of any two values recited above.

According to the graphene active material layer, other conductive agents, thickening agents, binders and the like can not be added in the preparation process, the internal resistance of the negative electrode plate can be remarkably reduced, the thickness of the graphene active material layer is easier to adjust, and the preparation process is simplified.

Negative pole piece

In a second aspect, the embodiment of the application also provides a negative electrode plate. The negative electrode plate comprises a negative electrode current collector and a graphene active material layer, wherein the graphene active material layer is arranged on at least one surface of the negative electrode current collector, is formed by etching a laser source, and comprises doping elements and carbon elements which are connected in a chemical bonding mode. Of course, the negative electrode sheet may also be prepared from any of the embodiments of the first aspect of the present application. As an example, the negative electrode current collector has two surfaces opposing in its own thickness direction, and the graphene active material layer is provided on either one or both of the two surfaces opposing the negative electrode current collector.

In some embodiments, the graphene active material layer may have a thickness of 30 μm to 120 μm. When the thickness of the graphene active material layer is in the above range, the energy density of the battery cell can be improved. Illustratively, the graphene active material layer may have a thickness of 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, or a range of any two of the above numerical values. In the present embodiment, the thickness of the graphene active material layer refers to the thickness of the graphene active material layer on one surface of the negative electrode current collector.

The graphene active material layer can effectively improve gram capacity due to the introduction of doping elements.

Illustratively, the negative electrode sheet may have a gram capacity of 400mAh/g, 405 mAh/g, 410 mAh/g, 418 mAh/g, 420 mAh/g, 422 mAh/g, 425 mAh/g, 428 mAh/g, 430 mAh/g, 432 mAh/g, 435 mAh/g, 438mAh/g, 439mAh/g, 440mAh/g, 441mAh/g, 442mAh/g, 443mAh/g, 444mAh/g, 445mAh/g, 446mAh/g, 447mAh/g, 448mAh/g, 449mAh/g, 450mAh/g, 451mAh/g, 452mAh/g, 454mAh/g, 455mAh/g, 456 h/g, 458 h/g, 459mAh/g, 460mAh/g, 461mAh/g, 470 mAh/g, 463, 475 mAh/g, 453mAh/g, 480mAh/g, or a range of values of any two of these values.

In some embodiments, the graphene active material layer is presented as a plurality of graphene sheets, each having a pore-like structure. In an embodiment of the present application, the porous structure comprises pores; the pores represent a recessed structure recessed with respect to the outer surface of the graphene sheet and recessed into the interior of the graphene active material layer, or are embodied as through holes penetrating the graphene sheet layer. The graphene sheets may have a plurality of holes therein, and the plurality of holes may be disposed in parallel and/or in a cross arrangement therebetween. The composition of the porous structure includes pore size, pore length, pore size distribution, and the like. The pore diameter can be micro pore, meso pore or macropore. Micropores refer to pores having a diameter of less than about 2 nanometers. Mesopores refer to pores having a diameter of from about 2 nanometers to about 50 nanometers. Macropores refer to pores having a diameter greater than 50 nanometers.

In the embodiment of the application, the holes of the hole-shaped structures can be nano holes, so that the structural strength of the graphene sheet is improved, and the transmission of active ions is facilitated. Alternatively, the pore size of the pore structure is 1nm to 80nm. Illustratively, the pore size of the pore structure may be 1nm, 2nm, 5nm, 8nm, 10nm, 12nm, 15nm, 18nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 70nm, 80nm, or a range of any two of the numerical values recited above.

In some embodiments, the graphene active material layer has a porosity of 5% to 30%. When the porosity of the graphene active material layer is in the range, the tap density of the negative electrode plate can be improved, and the energy density of the battery cell can be improved. Illustratively, the graphene active material layer may have a porosity of 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30%, or a range of any two values recited above.

In the present embodiment, the porosity refers to a ratio of pore volume of the graphene active material layer to the total volume of the graphene active material layer. The porosity can be measured according to GB/T24586 using a gas displacement method. Porosity w= (L1-L2)/L1 x 100%, where L1 is the apparent volume of the sample and L2 is the true volume of the sample. )

In some embodiments, the graphene active material layer has a specific surface area of 30m ² /g to 500m ² And/g. When the specific surface area of the graphene active material layer is in the above range, the cohesiveness of the graphene active material layer can be improved, and the tap density of the negative electrode plate can be improved, so that the energy density of the battery cell can be improved. Illustratively, the graphene active material layer may have a specific surface area of 30m ² /g、50 m ² /g、80 m ² /g、100 m ² /g、120 m ² /g、150 m ² /g、180 m ² /g、200 m ² /g、250 m ² /g、280 m ² /g、300 m ² /g、320 m ² /g、350 m ² /g、380 m ² /g、400 m ² /g、420 m ² /g、450 m ² /g、480 m ² /g、500 m ² Or/g is a range of any two values mentioned above.

In the embodiments of the present application, the specific surface area is in the meaning known in the art, and is generally expressed in m ² Units of/g may be measured using methods and apparatus known in the art. For example, reference may be made to GB/T19587-2017, which is performed using an inert gas (e.g. nitrogen) adsorption specific surface area analytical test method, which may be performed by a Tri-Star 3020 model specific surface area pore size analytical tester from Micromeritics, inc. of America, and calculated using BET (Brunauer Emmett Teller) method. The pore size distribution can be analyzed by the BJH (Barrett-Joiner-Halenda) model.

Battery cell

In a third aspect, the present application provides a battery cell. The battery cell comprises a positive pole piece and a negative pole piece.

In some embodiments, the negative electrode sheet is a negative electrode sheet prepared according to any one of the embodiments of the first aspect of the present application or a negative electrode sheet according to any one of the embodiments of the second aspect of the present application.

[ Positive electrode sheet ]

The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector.

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.

When the battery cell of the embodiments of the present application is a lithium ion battery, the positive electrode active material may include, but is not limited to, at least one of lithium-containing transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of the lithium transition metal oxide may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, and their respective modified compounds.

In some embodiments, to further increase the energy density of the battery cell, the positive electrode active material for a lithium ion battery may include a material having the general formula Li _a Ni _b Co _c M _d O _e A _f At least one of the lithium transition metal oxides and modified compounds thereof. A is more than or equal to 0.8 and less than or equal to 1.2,0.5 and less than or equal to B is less than or equal to 1, c is more than 0 and less than or equal to 1, d is more than 0 and less than or equal to 1, e is more than or equal to 1 and less than or equal to 0 and less than or equal to 1, f is more than or equal to 0 and less than or equal to 1, M comprises at least one of Mn, al, zr, zn, cu, cr, mg, fe, V, ti and B, and A comprises at least one of N, F, S and Cl.

As an example, the positive electrode active material for a lithium ion battery may include LiCoO ₂ 、LiNiO ₂ 、LiMnO ₂ 、LiMn ₂ O ₄ 、LiNi _1/3 Co _1/3 Mn _1/3 O ₂ （NCM333）、LiNi _0.5 Co _0.2 Mn _0.3 O ₂ （NCM523）、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ （NCM622）、LiNi _0.8 Co _0.1 Mn _0.1 O ₂ （NCM811）、LiNi _0.85 Co _0.15 Al _0.05 O ₂ 、LiFePO ₄ 、LiMnPO ₄ At least one of them.

When the battery cell of the present application is a sodium ion battery, the positive electrode active material may include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanionic materials (e.g., phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), prussian blue-based materials.

As an example, the positive electrode active material for a sodium ion battery may include NaFeO ₂ 、NaCoO ₂ 、NaCrO ₂ 、NaMnO ₂ 、NaNiO ₂ 、NaNi _1/2 Ti _1/2 O ₂ 、NaNi _1/2 Mn _1/2 O ₂ 、Na _2/3 Fe _1/3 Mn _2/3 O ₂ 、NaNi _1/3 Co _1/3 Mn _1/3 O ₂ 、NaFePO ₄ 、NaMnPO ₄ 、NaCoPO ₄ Prussian blue material with general formula X _p M’ _q (PO ₄ ) _r O _x Y _3-x At least one of the materials of (a) and (b). In the general formula X _p M’ _q (PO ₄ ) _r O _x Y _3-x Wherein p is more than 0 and less than or equal to 4, q is more than 0 and less than or equal to 2, r is more than or equal to 1 and less than or equal to 3, x is more than or equal to 0 and less than or equal to 2, and X comprises H ⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ And NH ₄ ⁺ M' is a transition metal cation, optionally at least one of V, ti, mn, fe, co, ni, cu and Zn, and Y is a halide anion, optionally at least one of F, cl and Br.

In the embodiment of the present application, the modifying compound for each positive electrode active material may be a compound obtained by doping modification and/or surface coating modification of the positive electrode active material.

In some embodiments, the positive electrode active material layer further optionally includes a positive electrode conductive agent. The present embodiment is not particularly limited in the kind of the positive electrode conductive agent, and the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, as an example. In some embodiments, the mass percent of the positive electrode conductive agent is less than or equal to 5% based on the total mass of the positive electrode active material layer.

In some embodiments, the positive electrode active material layer further optionally includes a positive electrode binder. The embodiment of the present application is not particularly limited in kind of the positive electrode binder, and the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate-based resin, as an example. In some embodiments, the mass percent of the positive electrode binder is less than or equal to 5% based on the total mass of the positive electrode active material layer.

In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a 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.

[ electrolyte ]

The battery cell also comprises an electrolyte, and the electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The type of electrolyte in the embodiments of the present application is not particularly limited, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

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

When the battery cell of the embodiments of the present application is a lithium ion battery, as an example, the electrolyte salt may include, but is not limited to, lithium hexafluorophosphate (LiPF ₆ ) Lithium tetrafluoroborate (LiBF) ₄ ) Lithium perchlorate (LiClO) ₄ ) Lithium hexafluoroarsenate (LiAsF) ₆ ) Lithium bis (fluorosulfonyl) imide (LiLSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), trifluoroLithium methanesulfonate (LiTFS), lithium difluorooxalato borate (LiDFOB), lithium dioxaoxalato borate (LiBOB), lithium difluorophosphate (LiPO) ₂ F ₂ ) At least one of lithium difluorophosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).

When the battery cell of an embodiment of the present application is a sodium ion battery, as an example, the electrolyte salt may include, but is not limited to, sodium hexafluorophosphate (NaPF ₆ ) Sodium tetrafluoroborate (NaBF) ₄ ) Sodium perchlorate (NaClO) ₄ ) Sodium hexafluoroarsenate (NaAsF) ₆ ) Sodium bis (fluorosulfonyl) imide (NaFSI), sodium bis (trifluoromethanesulfonyl) imide (NaTFSI), sodium (NaTFS) triflate, sodium (NaDFOB) difluorooxalato borate, sodium (NaBOB) dioxaoxalato borate, sodium (NaPO) ₂ F ₂ ) At least one of sodium difluorophosphate (NaDFOP) and sodium tetrafluorooxalate phosphate (NaDFOP).

As an example, the solvent may include, but is not limited to, at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene Carbonate (BC), fluoroethylene carbonate (FEC), methyl Formate (MF), methyl Acetate (MA), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), 1, 4-butyrolactone (GBL), sulfolane (SF), dimethylsulfone (MSM), methylsulfone (EMS), and diethylsulfone (ESE).

In some embodiments, 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.

[ isolation Membrane ]

In some embodiments, the battery cell further comprises a separator. The type of the separator according to the embodiment of the present invention 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 isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and 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 as 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 soft bag can be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).

The shape of the battery cell according to the embodiment of the present application is not particularly limited, and may be cylindrical, square, or any other shape. Fig. 2 shows a square-structured battery cell 5 as an example.

In some embodiments, as shown in fig. 3, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate coupled to the bottom plate, the bottom plate and the side plate enclosing to form a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 is used 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 52 through a winding process and/or a lamination process. The electrode assembly 52 is packaged in the receiving chamber. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 included in the battery cell 5 may be one or more, and may be adjusted according to the need.

Methods of preparing the battery cells of the embodiments of the present application are well known. In some embodiments, the positive electrode tab, separator, negative electrode tab, and electrolyte may be assembled to form a battery cell. As an example, the positive electrode sheet, the separator and the negative electrode sheet may be wound and/or laminated to form an electrode assembly, the electrode assembly is placed in an outer package, dried and then injected with an electrolyte, and the battery cell is obtained through vacuum packaging, standing, formation, shaping and other steps.

In some embodiments of the present application, the battery cells according to the present application may be assembled into a battery module, and the number of the battery cells included in the battery module may be plural, and the specific number may be adjusted according to the application and capacity of the battery module.

Fig. 4 is a schematic view of the battery module 4 as an example. As shown in fig. 4, in the battery module 4, a plurality of battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of battery cells 5 may be further fixed by fasteners. Alternatively, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

Fig. 5 and 6 are schematic views of the battery pack 1 as an example. As shown in fig. 5 and 6, a battery box and a plurality of battery modules 4 provided in the battery box may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 is used for covering the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

The battery of the embodiments of the present application may include one or more battery cells, and when the battery includes a plurality of battery cells, the battery may include a battery module or a battery pack.

Power utilization device

A fourth aspect of the present embodiments provides an electrical device comprising at least one of the battery cells, battery modules, or battery packs of the present application. The battery cell, the battery module, or the battery pack may be used as a power source of the electric device, and may also be used as an energy storage unit of the electric device. The electric device may be, but is not limited to, a mobile device (e.g., a cellular phone, a notebook computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

The power utilization device can select a battery cell, a battery module or a battery pack according to the use requirement.

Fig. 7 is a schematic diagram of the power consumption device 6 as an example. The electric device 6 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 consumer 6, a battery pack or battery module may be employed. As another example, the power consumption device may be a mobile phone, a tablet computer, a notebook computer, or the like. The power utilization device is required to be light and thin, and a battery unit can be used as a power supply.

Examples

The following embodiments more particularly describe the disclosure of the present application, which are for illustrative purposes only, as various modifications and changes within the scope of the disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages and ratios reported in the following embodiments are on a mass basis, and all reagents used in the embodiments are commercially available or synthetically obtained according to conventional methods and can be used directly without further treatment, as well as the instruments used in the embodiments are commercially available.

Example 1 preparation of lithium ion batteries

1、Preparation of positive electrode plate

The positive electrode active material lithium iron phosphate, a conductive agent Super P and a binder PVDF are mixed according to the mass ratio of 98:1:1, uniformly mixing the mixture in a proper amount of solvent N-methyl pyrrolidone (NMP) to obtain anode slurry; and coating the positive electrode slurry on a 12 mu m aluminum foil, and obtaining a positive electrode plate through the procedures of drying, cold pressing, slitting, cutting and the like.

2. Preparation of negative electrode plate

(1) Preparation of precursor film

Polyamic acid (PAA) was added to N-methylpyrrolidone (NMP) solvent and stirred under magnetic stirring for 0.5 hours to obtain a polyamic acid solution (the mass percentage of polyamic acid was 12.8 wt%).

Thiourea was added to the polyamic acid solution and mixed as a precursor solution (the mass percentage of thiourea was 8 wt%).

The precursor solution was coated on a 15 μm copper foil using a coater, and the thickness of the coated precursor solution was adjusted by adjusting the position of the doctor blade to 100 μm (the position of the doctor blade from the surface of the copper foil to 100 μm).

Placing the precursor solution in a vacuum oven at 80 ℃ for drying for 2 hours; then hot-pressing the mixture at 200 ℃ and 2MPa to form a precursor film.

(2) Preparation of graphene active material layer

Using CO ₂ And the laser emitter scans and etches the precursor film layer into a graphene active substance layer along the length direction of the copper foil. CO ₂ The laser wavelength of the laser transmitter is 10.6 mu m, the pulse width is approximately 14 mu s, the pulse number per inch is 1000, the output power range is 12W, the beam radius is approximately 100 mu m, the scanning speed is 5cm/s, and the laser intensity range born by the surface of the precursor film layer is 20J/cm ² The distance between the laser and the precursor film was 3 mm.

3. Preparation of electrolyte

And (3) in an environment with the water content less than 10ppm, mixing a nonaqueous organic solvent of ethylene carbonate EC and diethyl carbonate DMC according to a volume ratio of 1:1 to obtain an electrolyte solvent, and then mixing lithium hexafluorophosphate as a lithium salt with the mixed solvent to prepare the electrolyte with the lithium salt concentration of 1 mol/L.

4. Preparation of lithium ion batteries

Sequentially stacking and winding the positive pole piece, the polyethylene PE isolating film and the negative pole piece to obtain an electrode assembly; and placing the electrode assembly in an outer package, drying, injecting electrolyte, and performing vacuum packaging, standing, formation, shaping and other procedures to obtain the lithium ion battery.

Comparative example 1

A lithium ion battery was fabricated by a method similar to example 1, except that the negative electrode tab of comparative example 1 was fabricated as follows:

graphene serving as a negative electrode active material, a conductive agent Super P, a dispersing agent sodium carboxymethylcellulose CMC and a bonding agent styrene-butadiene rubber are uniformly mixed in deionized water to prepare a negative electrode slurry. The mass ratio of the artificial graphite, super P, CMC and styrene butadiene rubber in the solid component of the negative electrode slurry is 97:1:1:1. and coating the negative electrode slurry on a copper foil with 15 mu m, and drying and cold pressing at 85 ℃ to obtain the negative electrode plate.

Comparative example 2

A lithium ion battery was fabricated by a method similar to example 1, except that the negative electrode tab of comparative example 2 was fabricated as follows:

(1) Preparation of precursor film

Polyamic acid (PAA) was added to N-methylpyrrolidone (NMP) solvent and stirred under magnetic stirring for 0.5 hours to obtain a polyamic acid solution (the mass percent of polyamic acid is 12.8% by weight), which was used as a precursor solution.

(2) Preparation of graphene active material layer

Using CO ₂ Laser emissionAnd scanning and etching the precursor film layer to form a graphene active substance layer along the length direction of the copper foil. CO ₂ The laser wavelength of the laser transmitter is 10.6 mu m, the pulse width is approximately 14 mu s, the pulse number per inch is 1000, the output power range is 12W, the beam radius is approximately 100 mu m, the scanning speed is 5cm/s, and the laser intensity range born by the copper foil surface is 20J/cm ² The distance between the laser and the precursor film was 3 mm.

Example 2

A lithium ion battery was fabricated by a method similar to example 1, except that examples 2-1 to 2-12 were modified in the kind of the organic carbon source solution, unlike example 1.

Example 2-1 employed a polypropylene solution. Example 2-2 employs a polyvinyl alcohol solution. Examples 2-3 employed polyvinylpyrrolidone solutions. Examples 2-4 used polystyrene solutions. Examples 2-5 employed isobutyl vinyl ether solutions. Examples 2-6 employed polyvinyl acetate solutions. Examples 2-7 used cellulose acetate solutions. Examples 2-8 used chitosan acetic acid solution. Examples 2-9 used chitin acetic acid solution. Examples 2-10 employed cellulose acetate. Examples 2-11 employed cellulose acetate butyrate. Examples 2-12 employed cellulose acetate propionate.

Example 3

A lithium ion battery was fabricated by a method similar to example 1, except that examples 3-1 to 3-13 adjusted the kind of organic doping source, unlike example 1.

Example 4

A lithium ion battery was fabricated by a method similar to example 1, except that examples 4-1 to 4-6 adjusted the content of the organic doping source, unlike example 1.

Example 5

A lithium ion battery was fabricated by a method similar to example 1, except that examples 5-1 to 5-3 adjusted the thickness of the graphene active material layer, unlike example 1.

The relevant parameters for the examples and comparative examples are shown in tables 1 and 2.

Test part

1. Detection of graphene active material layer thickness

And taking the negative electrode plate, scanning the section of the negative electrode plate by adopting a scanning electron microscope SEM, and measuring the thickness of the graphene active material layer.

2. Negative pole piece resistance detection

Cutting small discs with the diameter of 10mm at the left, middle and right parts of the negative pole piece. And (3) opening the meta-energy science and technology pole piece resistance instrument indicator lamp, respectively placing the meta-energy science and technology pole piece resistance instrument indicator lamp at the proper positions of a probe of the membrane resistance instrument, clicking a start button, and reading after the indication is stable. And testing two positions of each small wafer, and finally calculating the average value of six measurements, namely the diaphragm resistance of the pole piece.

3. Gram capacity detection of negative pole piece

Taking the negative electrode piece, forming a counter electrode with a metal lithium piece, taking a Polyethylene (PE) film as a separation film, dripping a few drops of electrolyte which is the same as the battery monomer, and assembling the CR2430 button cell in a glove box protected by argon.

After the obtained button cell is stood for 12 hours, discharging is carried out to 0.005V at the temperature of 25 ℃ under the constant current of 0.1C, and the discharge capacity is recorded; then charged to 2.5V at a constant current of 0.1C, and the charge capacity was recorded. The ratio of the charge capacity to the mass of the negative electrode active material is the initial gram capacity of the negative electrode active material.

4. Lithium ion battery capacity retention rate detection

The button cell was charged and discharged at a constant current of 0.33C in the range of 0.005-2.5V at 25 ℃. The capacity retention after 500 cycles of the battery was calculated with the capacity of the first discharge being 100%. Capacity retention (%) after 500 cycles of the battery=discharge capacity of 500 th cycle/capacity of first discharge×100%.

Test results

The test results are shown in tables 1 and 2.

TABLE 1

TABLE 2

In the tables 1 and 2 of the drawings,

the mass percent of the organic doping source is calculated based on the total mass of the precursor solution;

the mass percentage content of the doping element refers to calculation based on the total mass of the graphene active material layer.

As can be seen from tables 1 and 2, in comparative examples 1 and 2, graphene is directly used as a main material of an active material layer, and compared with comparative examples 1 and 2, in the embodiment of the present application, a doping element is further introduced into the graphene active material layer, so that the gram capacity of the negative electrode sheet can be improved, and under the laser etching effect of the laser source, the doping element in the organic doping source and the carbon element in the graphene active material layer can be connected in a chemical bonding manner, and the doping element can further improve the gram capacity of the negative electrode sheet.

Therefore, the electrochemical performance of the negative electrode plate can be improved by doping different elements, so that the performance of the battery cell is further improved. Particularly, when the doping element is etched into a substance with better conductivity, for example, elements with conductivity such as iron, nickel, cobalt and the like are doped, the resistance of the negative electrode plate can be obviously reduced, the overall conductivity of the negative electrode plate is improved, and the capacity retention rate of the battery cell is improved.

By doping elements with high capacity or electrochemical activity, such as doped silicon, phosphorus and the like, the capacity can be contributed, and the gram capacity of the negative electrode plate can be improved.

As can be seen from fig. 8 to 12, the XRD pattern of example 1 shown in fig. 8 shows that the graphene active material layer has (002) and (100) two standard peaks, the peak at (200) is wider and the angle is lower than that of the graphite crystal, indicating that the degree of ordering between the graphene active material layers is reduced and the inter-layer distance is increased;

the Raman graph displacement of example 1 shown in fig. 9 shows D peak, G peak and 2D peak specific to few-layer graphene, and ID/ig=1.35, indicating that the obtained laser etched graphene has more defect structures, which is favorable for bonding with a negative current collector.

Fig. 10 shows a transmission electron microscopic view of the graphene active material layer of example 1; fig. 11 is a SEM image of a graphene active material layer formed by laser etching in example 1 of the present application. In fig. 11, a region corresponding to 15 μm is a copper foil region, and a region corresponding to 100 μm is a graphene active material layer. The graphene active material layer is compact and uniform, and the obtained graphene active material layer has a three-dimensional structure and a larger specific surface area.

Fig. 12 is an EDX elemental analysis diagram of the graphene active material layer formed by laser etching in example 1 of the present application, from which it can be seen that the graphene active material layer has a mass percentage of 91.1wt% and a sulfur element content of about 5.16wt%.

Fig. 13 shows the charge and discharge curves of the lithium ion battery of example 1 at 0.1C for 100 cycles, and it can be seen that the cycle performance of the lithium ion battery is relatively good and the capacity fade is slow.

Although illustrative embodiments have been shown and described, it will be understood by those skilled in the art that the foregoing embodiments are not to be construed as limiting the application and that changes, substitutions and alterations of the embodiments may be made without departing from the spirit, principles and scope of the application.

Claims

1. The preparation method of the negative electrode plate is characterized by comprising the following steps:

providing an organic carbon source solution;

adding an organic doping source containing doping elements into the organic carbon source solution, and mixing to form a precursor solution;

providing the precursor solution on the surface of the negative electrode current collector, and performing heat treatment on the precursor solution to form a precursor film layer;

and etching the precursor film layer by adopting a laser source to obtain a graphene active material layer containing the doping element, wherein the doping element is connected with carbon elements in the graphene active material layer in a chemical bonding mode.

2. The method according to claim 1, wherein the doping element includes at least one of a first element, a second element, and a third element;

The first element comprises one or more of sulfur element, phosphorus element, silicon element, selenium element and tin element;

the second element comprises one or more of iron element, cobalt element, nickel element, aluminum element and copper element;

the third element comprises one or more of boron element, germanium element, titanium element and magnesium element.

3. The method according to claim 1, wherein,

the doping element comprises sulfur element, and the organic doping source comprises one or more of thiourea, methionine, thioglycollic acid, 2-mercaptoethanol, thiobenzoic acid, diphenyl sulfoxide, cysteine and benzenesulfonic acid; and/or

The doping element comprises phosphorus element, and the organic doping source comprises one or more of phosphorous acid, alkyl phosphonic acid, alkyl phosphinic acid, phosphite ester, ethyl hypophosphite and alkyl phosphonite; and/or

The doping element comprises silicon element, and the organic doping source comprises one or more of trimethylsilanol, triethylsilanol, diphenylmethylsilane, hexamethyleneoxy disilane, trimethylphenylsilane and tetraethoxysilane; and/or

The doping element comprises tin element, and the organic doping source comprises one or more of monobutyl tin, dibutyl tin, tributyl tin oxide, triphenyl tin and dioctyl tin; and/or

The doping element comprises nickel element, and the organic doping source comprises one or more of nickel oxalate, nickel oleate, nickel propionate, nickel butyrate, nickel octoate and nickel lactate; and/or

The doping element comprises copper element, and the organic doping source comprises one or more of copper acetate, fatty acid copper and copper naphthenate; and/or

The doping element comprises boron element, and the organic doping source comprises one or more of phenylboric acid, diphenylboric acid, triphenylboron and trimethoxyboroxine; and/or

The doping element comprises selenium element, and the organic doping source comprises one or more of dimethyl selenium and diethyl diselenide; and/or

The doping element comprises germanium element, and the organic doping source comprises one or more of tetraethylgermanium, methyl germanium mercaptide, butyl germanium mercaptide and octyl germanium mercaptide; and/or

The doping element comprises iron element, and the organic doping source comprises one or more of ferrous lactate, ferric citrate and ferric glycine; and/or

The doping element comprises cobalt element, and the organic doping source comprises one or more of cobalt oxalate and cobalt acetate; and/or

The doping element comprises titanium element, and the organic doping source comprises one or more of orthotitanate and butyl titanate; and/or

The doping element comprises aluminum element, and the organic doping source comprises one or more of triethylaluminum, triisobutylaluminum and diethyl aluminum chloride; and/or

The doping element comprises magnesium element, and the organic doping source comprises one or more of magnesium glycinate, magnesium citrate and magnesium lactate.

4. The method according to claim 1, wherein,

the organic doping source is present in an amount of 0.2wt% to 20wt% based on the total mass of the precursor solution.

5. The method of claim 1, wherein the precursor solution has a thickness of 40 μm to 150 μm.

6. The method of claim 1, wherein the step of thermally treating the precursor solution to form a precursor film comprises:

first heat treating the precursor solution to remove at least a portion of the solvent in the precursor solution and retain the solute in the precursor solution;

and performing a second heat treatment on the solute in the precursor solution and providing an external force to the solute to form a precursor film layer.

7. The method of claim 1, wherein the precursor film layer has a thickness of 30 μm to 120 μm.

8. The method of claim 1, wherein the step of providing an organic carbon source solution comprises: and dissolving an organic carbon source in a solvent to obtain an organic carbon source solution, wherein the organic carbon source comprises one or more of polyamic acid, polyvinylpyrrolidone, isobutyl vinyl ether, polyvinyl acetate, cellulose ester compounds, polyolefin compounds and polysaccharide compounds.

9. The method according to claim 8, wherein,

the cellulose ester compound comprises one or more of cellulose acetate, cellulose acetate butyrate and cellulose acetate propionate; and/or

The polyolefinic alcohol compound comprises polyvinyl alcohol and/or polypropylene alcohol; and/or

The polyolefin compound comprises polypropylene and/or polystyrene; and/or

The polysaccharide compound comprises one or more of cellulose, chitosan and chitin.

10. The method according to claim 1, wherein,

the current collector comprises a metal substrate; or (b)

The current collector includes an organic polymer layer and a metal layer disposed on at least one surface of the organic polymer layer, wherein the precursor solution is provided to the surface of the metal layer.

11. The method of manufacturing according to claim 1, wherein the laser source comprises one or more of a carbon dioxide laser source, a diode laser source, an argon ion laser source, a nitrogen laser source, a red laser source, a blue laser source, and a femtosecond laser source.

12. The method of claim 11, wherein the carbon dioxide laser source has an output power of 10W to 30W.

13. The negative electrode plate is characterized by comprising a negative electrode current collector and a graphene active material layer, wherein the graphene active material layer is positioned on at least one surface of the negative electrode current collector, the graphene active material layer is formed by etching a laser source, and the graphene active material layer comprises a doping element and a carbon element which are connected in a chemical bonding mode.

14. The negative electrode tab of claim 13, wherein the doping element is present in an amount of 0.1wt% to 10wt%, based on the total mass of the graphene active material layer.

15. The negative electrode tab of claim 13, wherein the graphene active material layer has a thickness of 30 μιη to 120 μιη; and/or

The negative electrode plate takes lithium metal as a counter electrode, and in a charge-discharge curve obtained by testing in the range of 0.005V to 2.5V, the charge gram capacity of 0.005V to 2.5V is 400mAh/g to 480mAh/g.

16. The negative electrode sheet according to claim 13, wherein the graphene active material layer has a pore-like structure,

the pore diameter of the pore-shaped structure is 1nm to 80nm; and/or

The graphene active material layer has a porosity of 5% to 30%; and/or

The specific surface area of the graphene active material layer is 30m ² /g to 500m ² /g。

17. A battery cell comprising a negative electrode tab according to any one of claims 13 to 16.

18. A battery comprising the battery cell of claim 17.

19. An electrical device comprising the battery of claim 18.