WO2024045158A1 - Amide compound and preparation method therefor, electrode sheet, secondary battery, and electric device - Google Patents

Abstract

The present application relates to an amide compound and a preparation method therefor, an electrode sheet, a secondary battery, and an electric device. The amide compound can be added into an electrode sheet slurry as a wetting agent, to effectively ameliorate the dynamic problem of electrolyte wetting and significantly improve the wettability of an electrolyte to the electrode sheet, thereby reducing the battery impedance, and improving the electrochemical performance; moreover, increasing of wetting time or high-temperature standing is not needed, such that the production cost can be reduced, and the production efficiency can be improved.

Description

Amide compounds and preparation methods thereof, pole pieces, secondary batteries and electrical devices Technical field

The present application relates to the technical field of lithium batteries, and in particular to an amide compound and its preparation method, pole piece, secondary battery and electrical device.

Background technique

As lithium-ion batteries become more and more widely used in electric vehicles, portable electronic devices, and grid energy storage, there is an urgent need for higher energy density lithium-ion batteries to meet the growing market demand. In recent years, in addition to developing new battery chemistries, materials or systems, thick electrode structure design does not require changing the electrochemical basis of existing batteries, and can increase battery energy by increasing the proportion of electrochemically active substances in the battery. density and therefore more versatile and easier to implement.

However, a thick electrode structure will seriously affect the diffusion rate of lithium ions, resulting in a decrease in battery rate performance, and a higher compaction density will make the electrode piece's leakage ability worse and the electrolyte distribution in the electrode uneven. Wetting is difficult and the impedance increases, which is not conducive to the transmission of lithium ions, resulting in a decrease in electrochemical performance. In order not to affect the infiltration of the pole pieces, the infiltration time is usually increased or left to stand at high temperature, but this will increase the process time and reduce production efficiency.

Contents of the invention

According to various embodiments of the present application, the first aspect of the present application provides an amide compound having the following structural characteristics:

Wherein, R ₁ is a C1-C15 alkyl group substituted or unsubstituted by one or more R ₀ ;

R ₂ is a C1-C15 alkyl group substituted or unsubstituted by one or more R ₀ ;

Each time R ₀ appears, it is independently selected from one of the substituents of the following group: H, C3-C8 heterocyclic group, C1-C8 sulfonate ester group, C1-C8 ester group, C1-C8 phosphoric acid Ester group, C1-C8 alkoxy group, C1-C8 alkylthio group, C2-C8 alkenyl group and C2-C8 alkynyl group.

The second aspect of the application also provides a method for preparing amide compounds, including the following steps:

Conduct amidation reaction between compound 1 and compound 2 to prepare intermediate 1;

Perform amidation reaction between intermediate 1 and compound 3 to prepare the amide compound;

Or, perform an amidation reaction between compound 1 and compound 3 to prepare intermediate 2;

Perform amidation reaction between intermediate 2 and compound 2 to prepare the amide compound;

Among them, the structures of compound 1, compound 2, compound 3, intermediate 1 and intermediate 2 are as follows:

A third aspect of the present application also provides a sizing agent, the composition of which includes one or more of the amide compounds shown in the first aspect.

A fourth aspect of the present application also provides a pole piece slurry, the composition of which includes an electrode active material, the wetting agent described in the third aspect, and a solvent.

The fifth aspect of the present application also provides a method for preparing a pole piece, including the following steps:

The electrode layer is prepared on the surface of the current collector using the pole piece slurry described in the fourth aspect.

A sixth aspect of the present application also provides a pole piece, which includes a current collector and an electrode layer disposed on the surface of the current collector. The composition of the electrode layer includes an electrode active material and the wetting agent described in the third aspect.

A seventh aspect of the present application also provides a secondary battery, including the pole piece described in the sixth aspect.

An eighth aspect of the present application further provides an electrical device, including a secondary battery selected from the seventh aspect of the present application.

Description of drawings

Figure 1 is a schematic diagram of a secondary battery according to an embodiment of the present application;

Figure 2 is an exploded view of the secondary battery according to an embodiment of the present application shown in Figure 1;

Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application;

Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application;

Figure 5 is an exploded view of the battery pack according to an embodiment of the present application shown in Figure 4;

Figure 6 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application;

Explanation of reference symbols:

1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery module; 5. Secondary battery; 51. Case; 52. Electrode assembly; 53. Cover; 6. Electrical device;

Figure 7 is the infrared spectrum of the sizing agent 1 used in Example 1 of the present application.

Detailed ways

Embodiments specifically disclosing the amide compounds and their preparation methods, pole pieces, secondary batteries, and electrical devices of the present application will be described in detail below with appropriate reference to the accompanying drawings. However, unnecessary detailed explanations may be omitted. For example, detailed descriptions of well-known matters may be omitted, or descriptions of substantially the same structure may be repeated. This is to prevent the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

"Ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5. In this application, unless stated otherwise, the numerical range "a-b" represents an abbreviated 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 in this article, and "0-5" is just an abbreviation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

If there is no special instructions, all steps of the present application can be performed sequentially or randomly, and are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, mentioning that the method may also include step (c) 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 also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.

If there is no special explanation, the words "include" and "include" mentioned in this application represent open expressions, which may also be closed expressions. For example, "comprising" and "comprising" may mean that other components not listed may also be included or included, or only the listed components may be included or included.

In this application, the term "or" is inclusive unless otherwise specified. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).

If there is no special explanation, in this application, the term "alkyl" refers to a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof, losing one hydrogen Atomically generated monovalent residue. Phrases containing this term, for example, "C1-C15 alkyl" refer to alkyl groups containing 1 to 15 carbon atoms, and each occurrence can be independently C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, C10 alkyl, C11 alkyl, C12 alkyl, C13 alkyl, C14 alkyl, C15 alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH ₃ ), ethyl (Et, -CH ₂ CH ₃ ), 1-propyl (n-Pr, n-propyl, -CH ₂ CH ₂ CH ₃ ), 2-propyl (i-Pr, i-propyl, -CH(CH ₃ ) ₂ ), 1-butyl (n-Bu, n-butyl, -CH ₂ CH ₂ CH ₂ CH ₃ ) , 2-methyl-1-propyl (i-Bu, i-butyl, -CH ₂ CH (CH ₃ ) ₂ ), 2-butyl (s-Bu, s-butyl, -CH (CH ₃ )CH ₂ CH ₃ ), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH ₃ ) ₃ ), 1-pentyl (n-pentyl, -CH ₂ CH ₂ CH ₂ CH ₂ CH ₃ ), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH ₂ CH ₃ ) ₂ ), 2-methyl-2-butyl (-C( CH ₃ ) ₂ CH ₂ CH ₃ ), 3-methyl-2-butyl (-CH(CH ₃ )CH(CH ₃ ) ₂ ), 3-methyl-1-butyl (-CH ₂ CH ₂ CH (CH ₃ ) ₂ ), 2-methyl-1-butyl (-CH ₂ CH(CH ₃ )CH ₂ CH ₃ ), 1-hexyl (- CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₃ ), 2-Hexyl (-CH(CH ₃ )CH ₂ CH ₂ CH ₂ CH ₃ ), 3-hexyl (-CH(CH ₂ CH ₃ )(CH ₂ CH ₂ CH ₃ )), 2-methyl-2-pentan Base (-C(CH ₃ ) ₂ CH ₂ CH ₂ CH ₃ ), 3-methyl-2-pentyl (-CH(CH ₃ )CH(CH ₃ )CH ₂ CH ₃ ), 4-methyl-2 -Pentyl (-CH(CH ₃ )CH ₂ CH(CH ₃ ) ₂ ), 3-methyl-3-pentyl (-C(CH ₃ )(CH ₂ CH ₃ ) ₂ ), 2-methyl- 3-Pentyl (-CH(CH ₂ CH ₃ )CH(CH ₃ ) ₂ ), 2,3-dimethyl-2-butyl (-C(CH ₃ ) ₂ CH(CH ₃ ) ₂ ), 3 , 3-dimethyl-2-butyl (-CH(CH ₃ )C(CH ₃ ) ₃ and octyl (-(CH ₂ ) ₇ CH ₃ ).

If there is no special explanation, in this application, the term "alkoxy" refers to a group with the structure -O-alkyl, that is, an alkyl group as defined above is connected to an adjacent group of the parent core structure via an oxygen atom. . Phrases containing this term, for example, "C1-C8 alkoxy" mean that the alkyl moiety contains 1 to 8 carbon atoms and each occurrence can be independently C1 alkoxy, C4 alkoxy, C5 Alkoxy, C6 alkoxy, C7 alkoxy or C8 alkoxy. Suitable examples include, but are not limited to: methoxy (-O-CH ₃ or -OMe), ethoxy (-O-CH ₂ CH ₃ or -OEt), and tert-butoxy (-OC(CH ₃ ) ₃ or-OtBu).

If there is no special explanation, in this application, the term "alkylthio" refers to a group with the structure -S-alkyl, that is, an alkyl group as defined above is connected to an adjacent group of the parent core structure via a sulfur atom. . Phrases containing this term, for example, "C1-C8 alkylthio" mean that the alkyl moiety contains 1 to 8 carbon atoms, and each occurrence can be independently C1 alkylthio, C4 alkylthio, C5 Alkylthio, C6 alkylthio, C7 sulfoxy or C8 alkylthio. Suitable examples include, but are not limited to: methylthio (-S-CH ₃ or -SMe), ethylthio (-S-CH ₂ CH ₃ or -SEt), and tert-butylthio (-SC(CH ₃ ) ₃ or-StBu).

If there is no special explanation, in this application, the term "alkenyl" refers to a normal carbon atom, a secondary carbon atom, a tertiary carbon atom or a cyclic carbon atom with at least one unsaturated site, that is, a carbon-carbon sp2 double bond. A monovalent residue resulting from the loss of a hydrogen atom in a hydrocarbon. Phrases containing this term, for example, "C2-C8 alkenyl" refer to alkenyl groups containing 2 to 8 carbon atoms, and each occurrence may be independently C2 alkenyl, C3 alkenyl, C4 alkenyl, C5 alkenyl, C6 alkenyl, C7 alkenyl or C8 alkenyl. Suitable examples include, but are not limited to: vinyl (-CH= _CH2 ), allyl ( _-CH2CH = _CH2 ), cyclopentenyl ( _-C5H7 ), and 5- _hexenyl (- CH ₂ CH ₂ CH ₂ CH ₂ CH=CH ₂ ).

If there is no special explanation, in this application, the term "alkynyl" refers to a group containing a normal carbon atom, a secondary carbon atom, a tertiary carbon atom or a cyclic carbon atom with at least one unsaturated site, that is, a carbon-carbon sp triple bond. A monovalent residue resulting from the loss of a hydrogen atom in a hydrocarbon. Phrases containing this term, for example, "C2-C8 alkynyl" refer to an alkynyl group containing 2 to 8 carbon atoms, and each occurrence can be independently C2 alkynyl, C3 alkynyl, or C4 alkynyl , C5 alkynyl, C6 alkynyl, C7 alkynyl or C8 alkynyl. Suitable examples include, but are not limited to: ethynyl (-C≡CH) and propargyl (-CH ₂ C≡CH).

If there is no special explanation, in this application, the term "heterocyclyl" means that at least one carbon atom is replaced by a non-carbon atom on the basis of an aryl group. The non-carbon atom can be an N atom, an O atom, or an S atom. Atoms etc. For example, "C3~C8 heteroaryl" refers to a heteroaryl group containing 3 to 8 carbon atoms. Each time it appears, it can be independently C3 heteroaryl, C4 heteroaryl, C5 heteroaryl, C6 Heteroaryl, C7 heteroaryl or C8 heteroaryl. Suitable examples include, but are not limited to: furan, benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole, imidazole, oxazole, oxadiazole, thiazole, tetrazole, indole, carbazole, pyrrozo Imidazole, pyrrolopyrrole, thienopyrrole, thienothiophene, furopyrrole, furanofuran, thienofuran, benzisoxazole, benzisothiazole, benzimidazole, pyridine, pyrazine, pyridazine, pyrimidine , triazine, quinoline, isoquinoline, o-diazonaline, quinoxaline, phenanthridine, primidine, quinazoline and quinazolinone.

If there is no special explanation, in this application, the term "sulfonate group" has the structure:

group, where R represents an alkyl group, for example, "C1-C8 sulfonate group" means that R in the above structure is a C1-C8 alkyl group.

If there is no special explanation, in this application, the term "ester group" refers to a substance with the structure

group, where R represents an alkyl group, for example, "C1-C8 sulfonate group" means that R in the above structure is a C1-C8 alkyl group.

If there is no special explanation, in this application, the term "phosphate group" refers to a substance with the structure

group, where R represents an alkyl group, for example, "C1-C8 phosphate group" means that R in the above structure is a C1-C8 alkyl group.

This application provides an amide compound, which has the following structural characteristics:

Wherein, R ₁ is a C1-C15 alkyl group substituted or unsubstituted by one or more R ₀ ;

R ₂ is a C1-C15 alkyl group substituted or unsubstituted by one or more R ₀ ;

Each time R ₀ appears, it is independently selected from one of the substituents of the following group: H, C3-C8 heterocyclic group, C1-C8 sulfonate ester group, C1-C8 ester group, C1-C8 phosphoric acid Ester group, C1-C8 alkoxy group, C1-C8 alkylthio group, C2-C8 alkenyl group and C2-C8 alkynyl group.

The above-mentioned amide compounds can be added to the electrode slurry as a wetting agent to effectively improve the kinetic problems of electrolyte infiltration and significantly improve the wettability of the electrolyte to the electrodes, thereby reducing battery impedance and improving electrochemical performance without adding Wetting time or standing at high temperature can reduce manufacturing costs and improve production efficiency.

At the same time, when the above-mentioned amide compound is added in a small amount, it can significantly improve the wettability of the electrolyte to the electrode piece. In particular, the above-mentioned amide compounds can effectively improve the wettability of electrolyte to thick electrodes.

Without limitation, the possible reasons why the above-mentioned amide compounds improve the wettability of the pole piece are as follows:

The molecules form a one-dimensional network structure through π-π conjugation of the benzene ring. Combined with the specific structures of R ₁ and R ₂ , a three-dimensional network is formed, which can bind the electrolyte molecules. With specific amide groups, the electrolyte solution can be realized rapid infiltration and increase the migration rate of electrolyte. In this way, the wettability and liquid retention capacity of the electrode piece are improved, the contact between the electrolyte and the active particles is increased, the mass transfer probability is increased, the lithium ion migration number is increased, the probability of lithium dendrites appearing is reduced, and the risk of cell short circuit is reduced, thereby improving the performance of the electrode. Dynamic performance, improve interface dynamics and cycle performance of secondary batteries, achieve fast charging, reduce the risk of lithium precipitation, improve cell safety, while reducing production costs, shortening infiltration time, and increasing production capacity.

Furthermore, pole pieces are generally prepared by traditional wet pulping, which is a slurry that is uniformly mixed with active materials, binders, conductive agents, dispersants and solvents, and is then coated on the current collector and rolled. , prepared after die cutting. This method has a certain range limit on the solid content of the slurry. If the solid content is too high, the coating cannot be completed. Compared with traditional wet pulping, dry electrode technology does not use any solvent in the preparation process of pole pieces. The pole pieces can be prepared only by mixing dry powder. The preparation process is environmentally friendly and pollution-free, and can be used to a large extent. to reduce the production cost of the battery. However, during the preparation process of the dry electrode, uneven distribution of the powder in the pole piece is easy to occur, and there is no solvent film. During the rolling process, it is difficult for the particles to slip and the pole piece is difficult to be pressed. Therefore, it is impossible to achieve high-pressure solidification of the pole piece and to ensure a high-energy density battery. Moreover, during the rolling process of the pole piece, the active particles easily break the fibrillated binder (such as PTFE), thus reducing the binding capacity of the binder. To improve the utilization efficiency, an excessive amount of binder needs to be added, and the binder content reaches 5% to 10%, which reduces the proportion of active materials and reduces the energy density of the battery. Quasi-dry electrode technology takes into account the advantages of traditional wet pulping and dry electrode technology. It adds a small amount of solvent during the material preparation process, so the extruded film can greatly promote particle slippage during the roll thinning process. The function of the solvent is similar to that of a "lubricant", so the diaphragm is not easily over-rolled, the membrane is softer, the processing performance is better, and the electrode piece is easier to be compacted, realizing a high energy density battery, and is especially suitable for thick electrode structures preparation. However, traditional wetting agents are not suitable for quasi-dry electrode technology. The reason is that in quasi-dry electrode systems, traditional wetting agents are not enough to provide sufficient electrolyte infiltration capabilities and cannot form a three-dimensional network structure to fully Binding electrolyte molecules, if the added amount is increased, the energy density of the battery core will be reduced. The above-mentioned amide compounds provided by this application can effectively solve this problem and can be used as wetting agents in quasi-dry pole piece systems to prepare thick electrode structures and increase the energy density of the battery core.

In some embodiments, R ₂ is unsubstituted C1-C15 alkyl. Further, R ₂ is an unsubstituted C1-C8 alkyl group. Furthermore, R ₂ is an unsubstituted C1-C5 alkyl group.

In other embodiments, R ₂ is a C1-C15 alkyl group substituted by one or more R ₀ .

In some embodiments, R ₁ is a C1-C10 alkyl group substituted or unsubstituted by one or more R ₀ . Further, R ₁ is a C1-C6 alkyl group substituted or unsubstituted by one or more R ₀ .

In some embodiments, each occurrence of R ₀ is independently selected from one of the substituents of the following group: C1-C5 sulfonate ester group, C1-C5 ester group, C1-C5 phosphate ester group, C1 ~C5 alkoxy group, C1~C5 alkylthio group, C2~C5 alkenyl group and C2~C5 alkynyl group.

In some embodiments, each occurrence of R ₀ is independently selected from one of the substituents of the following group: C1-C4 sulfonate ester group, C1-C3 ester group, C1-C4 phosphate ester group, C1 ~C3 alkoxy group, C1~C3 alkylthio group, C2~C3 alkenyl group and C2~C3 alkynyl group.

In some embodiments, each occurrence of R ₀ is independently selected from one of the following group of substituents:

In some embodiments, the amide compound is selected from one of the following compounds:

This application also provides a preparation method of amide compounds, including the following steps:

Conduct amidation reaction between compound 1 and compound 2 to prepare intermediate 1;

Perform amidation reaction between intermediate 1 and compound 3 to prepare the amide compound;

Or, perform an amidation reaction between compound 1 and compound 3 to prepare intermediate 2;

Perform amidation reaction between intermediate 2 and compound 2 to prepare the amide compound;

Among them, the structures of compound 1, compound 2, compound 3, intermediate 1 and intermediate 2 are as follows:

The present application also provides a sizing agent, the composition of which includes one or more of the above-mentioned amide compounds.

This application also provides a pole piece slurry, the composition of which includes an electrode active material, a wetting agent as described above, and a solvent.

In some embodiments, the mass percentage of the wetting agent in the pole piece slurry is 0.1% to 0.5%. This sizing agent can achieve significant improvement in wettability at a smaller mass percentage. At the same time, without intending to be limited to any theory or explanation, the inventor found that the mass proportion of the wetting agent in the pole piece slurry is within the above-mentioned appropriate range, which can effectively increase the electrolyte infiltration rate while making the pole piece It has high energy density, cycle performance and rate performance. If too much is added, it is not conducive to increasing the energy density, and if too little is added, the electrolyte infiltration rate will be reduced. Specifically, the mass percentage of the sizing agent includes but is not limited to: 0.1%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, and 0.5%. Further, the mass percentage of the sizing agent is 0.2% to 0.4%.

In some embodiments, the solvent includes one or more of water, alcoholic solvents, and ester solvents; optionally, the alcoholic solvent includes 1,3-propanediol, 1,2-propanediol, 1 , one or more of 4-butanediol and 1,3-butanediol; optionally, the ester solvent includes triethyl phosphate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and One or more types of propylene carbonate.

Further, in wet pulping, the solvent includes water.

Further, in the slurry preparation of quasi-dry electrode technology, the solvent includes one or more of water, alcoholic solvents and ester solvents; optionally, the alcoholic solvent includes 1,3-propanediol. , one or more of 1,2-propanediol, 1,4-butanediol and 1,3-butanediol; optionally, the ester solvent includes triethyl phosphate, ethylene carbonate, dicarbonate One or more of methyl ester, diethyl carbonate and propylene carbonate. Furthermore, in the slurry of quasi-dry electrode technology, the solvent includes water.

In some embodiments, the solid content of the pole piece slurry is <65%. Slurry prepared in this way as wet pulping.

In some embodiments, the solid content of the pole piece slurry is 65% to 85%. This serves as a slurry for quasi-dry electrode technology.

In some embodiments, the pole piece slurry further includes a binder. Optionally, the binder includes one or more of styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid and carboxymethyl chitosan. species, or the binder includes one or more copolymers of polytetrafluoroethylene (PTFE), acrylonitrile, acrylic acid and acrylamide, or a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, One or more of tetrafluoroethylene and hexafluoropropylene copolymers, polychlorotrifluoroethylene, ethylene and chlorotrifluoroethylene copolymers. Further, the adhesive includes polytetrafluoroethylene.

Further, in wet pulping, the binder includes styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid and carboxymethyl chitosan one or more of them. Further, the weight average molecular weight of the binder is greater than 100,000, and the solid content is 20% to 60%.

In some embodiments, the mass percentage of the binder in the pole piece slurry is 0.05% to 3%. Specifically, the mass percentage of the binder in the pole piece slurry includes but is not limited to: 0.05%, 0.1%, 0.5%, 1%, 1.2%, 1.5%, 1.7%, 2%, and 3%.

Further, in the pulping of quasi-dry electrode technology, the binder includes a first binder and a second binder.

Specifically, the first binder includes polytetrafluoroethylene (PTFE), tetrafluoroethylene and perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene and hexafluoropropylene copolymer, and polychlorotrifluoroethylene, ethylene Copolymers with chlorotrifluoroethylene, preferably polytetrafluoroethylene. Further, the weight average molecular weight of the first binder is greater than 10 million, and the SSG (relative standard density) is 2.13 to 2.19.

In some embodiments, the mass percentage of the first binder in the pole piece slurry is 0.05% to 0.5%. Specifically, the mass percentage of the first binder in the pole piece slurry includes but is not limited to: 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2%, 0.3%, 0.4%, 0.5% .

Specifically, the second binder includes one or a copolymer of more than two kinds of acrylonitrile, acrylic acid and acrylamide. Further, the second binder includes acrylic acid/acrylonitrile/acrylamide copolymer. Without limitation, the molar percentage of the three monomers of acrylic acid, acrylonitrile, and acrylamide is (30% to 60%): (20 %～40%): (20%～30%). Further optionally, the weight average molecular weight of the second binder is greater than 300,000, and the solid content is 4% to 7%.

In some embodiments, the mass percentage of the second binder in the pole piece slurry is 0.5% to 4%. Specifically, the mass percentage of the second binder in the pole piece slurry includes but is not limited to: 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, and 4%.

In some embodiments, in wet pulping, the pole piece slurry includes the following components in terms of mass percentage: 89.5% to 98.6% of electrode active material, 0.3% to 4% of conductive agent, 0.5% ~3% binder, 0.5% ~ 3% thickener and 0.1% ~ 0.5% sizing agent. The amount of solvent used is such that the solid content of the pole piece slurry is <65%.

In some embodiments, in the slurry preparation of quasi-dry electrode technology, the electrode piece slurry includes the following components in terms of mass percentage: 91% to 99.05% of electrode active materials, 0.3% to 4% of conductive agent, 0.05% to 0.5% of the first binder, 0.5% to 4% of the second binder and 0.1% to 0.5% of the sizing agent. The amount of solvent used is such that the solid content of the pole piece slurry is 65% to 85%. By rationally controlling the percentage content of each component, the components can be easily prepared into a lump material. The membrane is not easily rolled over, the membrane is softer, the processing performance is better, the pole piece is easier to be compacted, and it is easier to prepare. Thick electrode plates enable high energy density batteries. At the same time, the amount of solvent added in the formula system is much lower than that of the wet coating process, which greatly reduces drying energy consumption and reduces environmental pollution. The prepared membrane has a surface non-stick function, so the oven can be a winding oven. Therefore, the length of the oven can be greatly shortened, the equipment footprint can be reduced, and technical cost reduction can be achieved.

This application also provides a method for preparing pole piece slurry, which includes the following steps:

Mix the electrode active material, wetting agent as described above, and solvent.

It can be understood that the solution of the pole piece slurry is the same as above, and will not be described again here.

In some embodiments, the preparation method of the pole piece slurry is quasi-dry pulping.

In some embodiments, the preparation method of the pole piece slurry includes the following steps:

Mix the electrode active material and the first binder to prepare a first premix;

Mix the sizing agent, the second binder and the solvent to prepare a second premix;

The first premix and the second premix are mixed to prepare the pole piece slurry.

Without limitation, the equipment for mixing materials can be internal mixers, kneaders, twin-screw equipment, etc.

This application also provides a method for preparing a pole piece, which includes the following steps:

The electrode layer is prepared on the surface of the current collector using the pole piece slurry as described above.

In some embodiments, the pole piece slurry is prepared by wet pulping. Furthermore, the method of using the electrode piece slurry to prepare the electrode layer on the surface of the current collector may be coating.

In some embodiments, the electrode piece slurry is prepared by a slurrying method using quasi-dry electrode technology. It can be understood that the prepared pole piece slurry is usually a solid with a certain degree of softness and deformability, similar to a dough-like shape. Further, the step of using the pole piece slurry to prepare an electrode layer on the current collector surface includes:

Shape the pole piece slurry to prepare a diaphragm;

The diaphragm and the current collector are combined.

Without limitation, equipment for preparing the diaphragm may include a screw extruder, a hydraulic extruder, a plunger extruder, and the like. The threaded element of the screw element can be combined with one or more of threaded parts, meshing blocks, and toothed discs to fully balance the shear mixing and conveying capabilities. The thickness of the film is controlled through the extrusion die.

In some embodiments, the thickness of the diaphragm is 3 mm to 10 mm.

Without limitation, the diaphragm can be directly compounded with the current collector, or can be further thinned and transferred through one or more stages of rolling to be compounded with the current collector.

In some embodiments, a drying step is included after compounding. Without limitation, the drying can be done using a winding three-dimensional oven drying.

In some embodiments, the above-mentioned pole piece preparation method can achieve continuous production.

This application also provides a pole piece, which includes a current collector and an electrode layer disposed on the surface of the current collector. The composition of the electrode layer includes an electrode active material and a wetting agent as described above.

It can be understood that the current collector has two surfaces opposite in its own thickness direction, and the electrode layer is disposed on any one or both of the two surfaces.

In some embodiments, the mass percentage of the wetting agent in the pole piece is 0.1% to 0.5%. Specifically, the mass percentage of the sizing agent includes but is not limited to: 0.1%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, and 0.5%. Further, the mass percentage of the sizing agent is 0.2% to 0.4%.

In some embodiments, in the pole piece, the single-sided film layer weight of the electrode layer is ≥180 mg/1540.25mm ² . Further, the single-sided film layer weight of the electrode layer is 180 mg/1540.25mm ² to 250 mg/1540.25mm ² .

This application also provides a secondary battery, including the pole piece as described above.

The present application also provides an electrical device, including a secondary battery selected from the above.

The secondary battery and electric device of the present application will be described below with appropriate reference to the drawings.

In one embodiment of the present application, a secondary battery is provided.

Typically, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator. During the charging and discharging process of the battery, active ions are inserted and detached back and forth between the positive and negative electrodes. The electrolyte plays a role in conducting ions between the positive and negative electrodes. The isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.

Positive electrode piece

The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes the positive electrode active material of the first aspect of the present application.

As an example, the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material on a polymer material substrate. Among them, metal materials include but are not limited to aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc. Polymer material substrates (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) ) etc.)

In some embodiments, the thickness of the positive electrode current collector ranges from 10 μm to 25 μm. Further, the thickness of the positive electrode current collector is 10 μm to 16 μm.

In some embodiments, the cathode active material may include cathode active materials known in the art for batteries. As an example, the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO ₂ ), lithium nickel oxides (such as LiNiO ₂ ), lithium manganese oxides (such as LiMnO ₂ , LiMn ₂ O ₄ ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (also referred to as NCM ₃₃₃ ), LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (can also be abbreviated to NCM ₅₂₃ ), LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (can also be abbreviated to NCM ₂₁₁ ), LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (can also be abbreviated to NCM ₆₂₂ ), LiNi At least one of _0.8 Co _0.1 Mn _0.1 O ₂ (also referred to as NCM ₈₁₁ ), lithium nickel cobalt aluminum oxide (such as LiNi _0.85 Co _0.15 Al _0.05 O ₂ ) and its modified compounds. The olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO ₄ (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO ₄ ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.

In some embodiments, the positive electrode film layer further includes a binder. The binder in the pole piece is the same as mentioned above and will not be described again here.

In some embodiments, the positive electrode film layer optionally further includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components in a solvent (such as N -methylpyrrolidone), forming a positive electrode slurry, wherein the solid content of the positive electrode slurry is 40-80wt%, the viscosity at room temperature is adjusted to 5000-25000mPa·s, and the positive electrode slurry is coated on the surface of the positive electrode current collector , dried and cold-pressed by a cold rolling mill to form a positive electrode piece; the unit area density of the positive electrode powder coating is 150-350 mg/m ² , and the compacted density of the positive electrode piece is 3.0-3.6g/cm ³ , optionally 3.3 -3.5g/cm ³ . The calculation formula of the compacted density is

Compaction density = coating surface density / (thickness of electrode piece after extrusion - thickness of current collector).

Negative pole piece

The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.

As an example, the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material. The composite current collector can be formed by forming a metal material on a polymer material substrate. Among them, metal materials include but are not limited to copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc., and polymer material base materials include but are not limited to polypropylene (PP), polyethylene terephthalate Glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) and other base materials.

In some embodiments, the thickness of the negative electrode current collector ranges from 4 μm to 12 μm. Further, the thickness of the positive electrode current collector is 6 μm to 8 μm.

In some embodiments, the negative active material may be a negative active material known in the art for batteries. As an example, the negative active material may include at least one of the following materials: artificial graphite, natural graphite, mesocarbon microspheres, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide, silicon nanowires, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.

In some embodiments, the negative electrode film layer optionally further includes a binder. The binder in the pole piece is the same as mentioned above and will not be described again here.

In some embodiments, the negative electrode film layer optionally further includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na), lithium carboxymethylcellulose (CMC-Li)), etc. The weight ratio of the other additives in the negative electrode film layer is 0-15% by weight, based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water), forming a negative electrode slurry, wherein the solid content of the negative electrode slurry is 30-70wt%, and the viscosity at room temperature is adjusted to 2000-10000mPa·s; the obtained negative electrode slurry is coated on the negative electrode current collector, After the drying process and cold pressing, such as against rollers, the negative electrode piece is obtained. The negative electrode powder coating unit area density is 180~250mg/1540.25mm ² , and the negative electrode plate compacted density is 1.2~2.0g/ ^m3 .

electrolyte

The electrolyte plays a role in conducting ions between the positive and negative electrodes. There is no specific restriction on the type of electrolyte in this application, and it can be selected according to needs. For example, the electrolyte can be liquid, gel, or completely solid.

In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes electrolyte salts and solvents.

In some embodiments, the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), bisfluorosulfonyl Lithium amine (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium difluoromethane borate (LiBOB), lithium difluorophosphate (LiPO ₂ F ₂ ), lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP). The concentration of the electrolyte salt is usually 0.5-5mol/L.

In some embodiments, the solvent may be selected from fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) ), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate Ester (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB) , one or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulfone (ESE) kind.

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

Isolation film

In some embodiments, the secondary battery further includes a separator film. There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.

In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.

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

In some embodiments, the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.

In some embodiments, the secondary battery may include an outer packaging. The outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.

In some embodiments, the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag. The material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.

This application has no particular limitation on the shape of the secondary battery, which can be cylindrical, square or any other shape. For example, FIG. 1 shows a square-structured secondary battery 5 as an example.

In some embodiments, referring to FIG. 2 , the outer package may include a housing 51 and a cover 53 . The housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity. The positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged in the containing cavity. The electrolyte soaks into the electrode assembly 52 . The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

In some embodiments, secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.

Figure 3 is a battery module 4 as an example. Referring to FIG. 3 , in the battery module 4 , a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 . Of course, it can also be arranged in any other way. Furthermore, the plurality of secondary batteries 5 can be fixed by fasteners.

Optionally, the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.

In some embodiments, the above-mentioned battery modules can also be assembled into a battery pack. The number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.

Figures 4 and 5 show the battery pack 1 as an example. Referring to Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box 2 and a lower box 3 . The upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 . Multiple battery modules 4 can be arranged in the battery box in any manner.

In addition, the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application. The secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.

As the power-consuming device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

Figure 6 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the secondary battery for the electrical device, a battery pack or battery module can be used.

As another example, the device may be a mobile phone, a tablet, a laptop, etc. The device is usually required to be thin and light, and a secondary battery can be used as a power source.

Example

In order to make the technical problems, technical solutions and beneficial effects solved by this application clearer, this application will be further described in detail below with reference to the embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

If specific techniques or conditions are not specified in the examples, the techniques or conditions described in literature in the field or product instructions will be followed. If the manufacturer of the reagents or instruments used is not indicated, they are all conventional products that can be purchased commercially.

Example 1:

This embodiment provides a negative electrode plate and a lithium-ion secondary battery, and the preparation method is as follows:

(1) Preparation of positive electrode plate

Dissolve the positive active material lithium iron phosphate (LiFePO ₄ ), the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black in the solvent N-methylpyrrolidone (NMP) at a mass ratio of 97.3:2:0.7. After stirring and mixing evenly, the positive electrode slurry is obtained; after coating, cold pressing and drying, the positive electrode sheet is obtained. The coating weight is 400mg/1540.25mm ² and the solid content of the slurry is 63%. Select aluminum foil as the positive current collector, with a thickness of 15 μm.

(2) Preparation of negative electrode pieces

Combine the negative active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), thickener sodium carboxymethylcellulose (CMC-Na), and wetting agent 1 according to a mass ratio of 96.4%:0.7%: Dissolve 1.5%:1.2%:0.2% in solvent deionized water, stir thoroughly and mix evenly to obtain negative electrode slurry; prepare negative electrode pieces after coating, drying and cold pressing. The solid content of the slurry is 53%, and the weight of the electrode piece is 200mg/ 1540.25mm ² . Select aluminum foil as the negative electrode current collector, with a thickness of 7 μm. The binder styrene-butadiene rubber (SBR) has a weight average molecular weight of 200,000 and a solid content of 48%.

(3) Lithium-ion secondary battery preparation

The above-mentioned positive electrode piece, a 14 μm-thick polyethylene film as a separator, and the above-mentioned negative electrode piece are stacked in order so that the separator is between the positive electrode piece and the negative electrode piece to play an isolation role, and the bare electrode is wound. Batteries. The bare battery core is placed in the outer package, the electrolyte is injected into the dried battery, and after processes such as vacuum packaging, standing, formation, and shaping, the lithium-ion battery of Example 1 is obtained.

The structure of sizing agent 1 is:

Preparation method of sizing agent 1: 1.1 mol valeric acid and 1 mol 2-amino 2-phenylacetic acid, 0.1 g Zn powder, react at 130°C for 6 hours, obtain intermediate 1 through distillation and suction filtration; 1 mol intermediate 1 and 1.15 mol 2-Butylamine was catalyzed by 0.1g Zn powder, reacted at 45°C for 3 hours, and then obtained sizing agent 1 through distillation and suction filtration.

The infrared spectrum is shown in Figure 7: From the infrared spectrum, it can be seen that there are characteristic peaks of benzene rings between 1500 and 1670. The π-π conjugation between benzene rings self-assembles in one-dimensional direction to form a network, and then builds a three-dimensional network to constrain electrolysis. The liquid builds a high-speed channel for lithium ions. There are characteristic peaks of amide bonds at 1630~1690 and 3300~3500, which realizes rapid infiltration of the electrolyte and accelerates the migration of lithium ions.

Example 2:

This embodiment provides a negative electrode plate and a lithium-ion secondary battery. The preparation method is the same as that of Embodiment 1. The main differences are: the negative active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the additives. The mass ratio of the thickening agent carboxymethyl cellulose sodium (CMC-Na) and the wetting agent 1 is 96.3%:0.7%:1.5%:1.2%:0.3%. The solid content of the negative electrode slurry is 53%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Example 3:

This embodiment provides a negative electrode plate and a lithium-ion secondary battery. The preparation method is the same as that of Embodiment 1. The main differences are: the negative active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the additives. The mass ratio of the thickening agent sodium carboxymethyl cellulose (CMC-Na) and the sizing agent 1 is 96.2%:0.7%:1.5%:1.2%:0.4%. The solid content of the negative electrode slurry is 53%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Example 4:

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as in Embodiment 1. The main difference is that the preparation method of the negative electrode plate is as follows:

Mix artificial graphite, conductive carbon, and binder 1 in a dual planetary mixer to obtain solvent-free granular materials. Mix wetting agent 1, binder 2, and deionized water to form glue. The solvent-free granules and glue are kneaded. The process obtains pellet material, which is transported by a screw and extruded into a thick sheet by a die, which is then thinned by rolling and compounded with a current collector to obtain a negative electrode piece. The mass ratio of artificial graphite, conductive carbon, binder 1 (PTFE), binder 2 (acrylic acid/acrylonitrile/acrylamide copolymer) and sizing agent 1 is 97.0%:0.7%:0.1%:2%:0.2 %. The solid content of the negative electrode slurry is 70%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Among them, binder 1 has a weight average molecular weight of 20 million and an SSG of 2.19; binder 2 has a weight average molecular weight of 350,000 and a solid content of 5.5%. For the preparation method of binder 2, please refer to: use high-pressure nitrogen protection and perform polymerization reaction on an anionic polymerization device (for example, HTSCP series, SCP2009) at a pressure of 0.3 to 0.5MPa. During the reaction, nucleophiles are used as initiators. The monomers acrylic acid, acrylonitrile, and acrylamide are added in order, and the reaction is carried out for 50 minutes at a temperature of 25-40°C. The chain reaction is terminated by adding alcohols. The molar percentages of the three monomers are 40%:30%:30%.

Example 5:

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Embodiment 4. The main differences are: artificial graphite, conductive carbon, binder 1 (PTFE), binder 2 (acrylic acid/propylene). The mass ratio of nitrile/acrylamide copolymer) and sizing agent 1 is 96.9%:0.7%:0.1%:2%:0.3%. The solid content of the negative electrode slurry is 70%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Example 6:

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Embodiment 4. The main differences are: artificial graphite, conductive carbon, binder 1 (PTFE), binder 2 (acrylic acid/propylene). The mass ratio of nitrile/acrylamide copolymer) and sizing agent 1 is 96.8%:0.7%:0.1%:2%:0.4%. The solid content of the negative electrode slurry is 70%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Example 7:

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Embodiment 1. The main difference is that wetting agent 2 is used instead of wetting agent 1. In the chemical structure of sizing agent 2, R ₁ is replaced by an ester group, and the structure is as follows:

Preparation method of sizing agent 2: 1.15 mol diethyl malonate hydrolyzes to remove an ester group, reacts with 1 mol 2-amino 2-phenylacetic acid, 0.1 g Zn powder at 80°C for 10 hours, and obtains by distillation and suction filtration Intermediate 2: 1 mol of intermediate 2 and 1.2 mol of propylamine were catalyzed by 0.1 g of Zn powder, reacted at 60°C for 5 hours, and then sizing 2 was obtained by distillation and suction filtration.

Example 8:

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that in Embodiment 1. The main difference is that wetting agent 3 is used instead of wetting agent 1. In the chemical structure of sizing agent 3, R ₁ is replaced by an alkoxy group, and the structure is as follows:

Preparation method of sizing agent 3: 1.15 mol ethoxyacetic acid and 1 mol 2-amino 2-phenylacetic acid, 0.1 g Zn powder, react at 80°C for 10 hours, obtain intermediate 3 by distillation and suction filtration, 1 mol intermediate 3 and 1.15 mol ethylamine was catalyzed by 0.1 g Zn powder, reacted at 45°C for 3 hours, and then obtained sizing agent 3 through distillation and suction filtration.

Example 9:

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Embodiment 1. The main difference is that wetting agent 4 is used instead of wetting agent 1. In the chemical structure of sizing agent 4, R ₁ is substituted by alkenyl, and the structure is as follows:

Preparation method of sizing agent 4: 1.2 mol vinyl acetic acid and 1 mol 2-amino 2-phenylacetic acid, 0.1 g Zn powder, react at 100°C for 8 hours, obtain intermediate 4 through distillation and suction filtration, 1 mol intermediate 4 and 1.15 Mol methylamine was catalyzed by 0.1g Zn powder, reacted at 60°C for 3 hours, and then obtained sizing agent 4 through distillation and suction filtration.

Example 10:

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Embodiment 1. The main difference is that the infiltration agent 5 is used instead of the infiltration agent 1. In the chemical structure of sizing agent 5, R ₁ is replaced by a phosphate group, and the structure is as follows:

Preparation method of sizing agent 5: 1.2 mol of triethyl phosphoryl acetate is hydrolyzed to remove an ester group, then reacted with 1 mol of 2-amino 2-phenylacetic acid and 0.1 g of Zn powder at 130°C for 10 hours, and then obtained by distillation and suction filtration. Intermediate 5, 1 mol of intermediate 4 and 1.1 mol of butylamine were catalyzed by 0.1 g Zn powder, reacted at 60°C for 3 hours, and then distilled and filtered to obtain sizing agent 5.

Example 11:

This embodiment provides a negative electrode plate and a lithium-ion secondary battery. The preparation method is the same as that of Embodiment 1. The main differences are: the negative active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the additives. The mass ratio of the thickening agent sodium carboxymethyl cellulose (CMC-Na) and the sizing agent 1 is 96%:0.7%:1.5%:1.2%:0.6%. The solid content of the negative electrode slurry is 53%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Comparative example 1

This comparative example provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Example 1. The main difference is that: no wetting agent 1 is added, and the negative active material artificial graphite, the conductive agent acetylene black, and the binder butyl styrene are not added. The mass ratio of rubber (SBR) and thickener sodium carboxymethylcellulose (CMC-Na) is 96.6%:0.7%:1.5%:1.2%. The solid content of the negative electrode slurry is 53%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Comparative example 2

This comparative example provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Example 4. The main difference is that: no sizing agent 1, artificial graphite, conductive carbon, binder 1 (PTFE), and bonding agent 1 are added. The mass ratio of Agent 2 (acrylic acid/acrylonitrile/acrylamide copolymer) is 97.2%:0.7%:0.1%:2%. The solid content of the negative electrode slurry is 70%, and the weight of the electrode piece is 200mg/1540.25mm ² .

Comparative example 3

This embodiment provides a negative electrode plate and a lithium ion secondary battery. The preparation method is the same as that of Embodiment 1. The main difference is that a comparative sizing agent is used instead of sizing agent 1. The preparation method of the comparative sizing agent is the same as in Example 1, and its chemical structure is as follows:

The lithium-ion batteries prepared in the examples and comparative examples were tested, as follows:

(1) Lithium evolution test

Charge with a constant current of 1C to 3.65V, then charge with a constant voltage of 3.65V to a current of 0.05C, let it sit for 5 minutes, and then discharge with a constant current of 1C to 2.5V. The above is a charge and discharge cycle of the battery. After 10 cycles , charged at a constant voltage of 3.65V to a current of 0.05C. Disassemble the battery in a dry environment. The golden color on the surface of the negative electrode plate indicates that there is no separation, and the appearance of a silvery white area indicates separation.

(2) Electrolyte infiltration rate test

Test method: Use a capillary tube (diameter 1mm) to absorb a certain amount of electrolyte (height 2cm), so that the suction end of the capillary tube is in contact with the surface of the electrode plate. The electrode piece has a porous structure. Under capillary force, the electrolyte in the capillary can be sucked out. The time required for the electrolyte to be completely absorbed is recorded, and the electrolyte infiltration rate is calculated.

The calculation method of electrolyte infiltration rate: electrolyte density * volume of electrolyte in the capillary / time required for the electrolyte to be completely absorbed. The test results are shown in Table 1.

(3)DCR performance test

Test method: At 25°C, charge to full charge at 0.33C, then discharge 0.5Cn at 0.33C (Cn represents battery capacity) to adjust the secondary battery to 50% SOC, let it stand for 30 minutes, and the end voltage of rest is V1, Then discharge 3C for 30 seconds, discharge cut-off voltage V2, then discharge 3C for 30 seconds, let it stand for 40 seconds, and charge 3C for 30 seconds;

Calculation method: DCR=(V1-V2)/I, where V1 is the static end voltage, V2 is the discharge cut-off voltage, and I is the discharge current. The test results are shown in Table 1.

(4) Rate performance test

Rate discharge: charge at 0.33C to 3.65V constant voltage, charge until the current is 0.05C, let it sit for 5 minutes, discharge at 0.33C to 2.5V and measure the discharge capacity during the period, let it stand for 30 minutes; charge at 0.33C to 3.65V at constant voltage. until the current is 0.05C, let it stand for 5 minutes, discharge at 1C to 2.5V and measure the discharge capacity, and let it stand for 30 minutes; charge at 0.33C to a constant voltage of 3.65V, charge until the current is 0.05C, let it stand for 5 minutes, and discharge at 3C to 2.8V and measure the discharge capacity, and leave it for 30 minutes; charge at 0.33C to a constant voltage of 3.65V, charge to a current of 0.05C, and leave it for 5 minutes, discharge it at 5C to 2.5V, and measure the discharge capacity, and leave it for 30 minutes minute.

Rate charging: charge at 0.33C to 3.65V constant voltage, charge until the current is 0.05C, let it sit for 5 minutes, discharge at 0.33C to 2.5V, and measure the charging capacity during the period, let it stand for 30 minutes; charge at 1C to 3.65V at constant voltage. until the current is 0.05C, let it sit for 30 minutes, discharge at 0.33C to 2.5V and measure the charging capacity, and let it stand for 30 minutes; charge at 3C with 3.65V constant voltage until the current is 0.05C, let it stand for 5 minutes, and discharge at 0.33C to 2.5V and measure the charging capacity, and leave it for 30 minutes; charge at 5C to 4.2V at a constant voltage, charge to a current of 0.05C, and leave it for 30 minutes, discharge at 0.33C to 2.5V, and measure the charging capacity, and leave it for 30 minutes minute.

The test results are shown in Tables 1 to 2 below:

Table 1 Preparation conditions and performance comparison of pole pieces of Examples and Comparative Examples

Table 2 Comparative Examples and Examples Magnification Comparison

It should be noted that the present application is not limited to the above-described embodiment. The above-mentioned embodiments are only examples. Within the scope of the technical solution of the present application, embodiments that have substantially the same structure as the technical idea and exert the same functions and effects are included in the technical scope of the present application. In addition, within the scope that does not deviate from the gist of the present application, various modifications to the embodiments that can be thought of by those skilled in the art, and other forms constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present application. .

Claims (20)

1. An amide compound has the following structural characteristics:

   

   Wherein, R ₁ is a C1-C15 alkyl group substituted or unsubstituted by one or more R ₀ ;

   R ₂ is a C1-C15 alkyl group substituted or unsubstituted by one or more R ₀ ;

   Each time R ₀ appears, it is independently selected from one of the substituents of the following group: H, C3-C8 heterocyclic group, C1-C8 sulfonate ester group, C1-C8 ester group, C1-C8 phosphoric acid Ester group, C1-C8 alkoxy group, C1-C8 alkylthio group, C2-C8 alkenyl group and C2-C8 alkynyl group.
2. The amide compound according to claim 1, wherein R ₂ is an unsubstituted C1-C15 alkyl group; optionally, R ₂ is an unsubstituted C1-C8 alkyl group; further optionally, R ₂ is an unsubstituted C1-C5 alkyl group.
3. The amide compound according to claim 1 or 2, characterized in that R ₁ is a C1-C10 alkyl group substituted or unsubstituted by one or more R ₀ ; optionally, R ₁ is a C1-C10 alkyl group substituted by one or more R 0 Each R ₀ is a substituted or unsubstituted C1-C6 alkyl group.
4. The amide compound according to any one of claims 1 to 3, characterized in that each time R ₀ appears, it is independently selected from one of the substituents of the following group: C1 to C5 sulfonate ester groups, C1 to C5 ester group, C1-C5 phosphate ester group, C1-C5 alkoxy group, C1-C5 alkylthio group, C2-C5 alkenyl group and C2-C5 alkynyl group.
5. The amide compound according to any one of claims 1 to 4, characterized in that each time R ₀ appears, it is independently selected from one of the following group of substituents:

   
6. The amide compound according to any one of claims 1 to 5, characterized in that the amide compound is selected from one of the following compounds:

   
7. A method for preparing amide compounds, which is characterized by comprising the following steps:

   Conduct amidation reaction between compound 1 and compound 2 to prepare intermediate 1;

   Perform amidation reaction between intermediate 1 and compound 3 to prepare the amide compound;

   Or, perform an amidation reaction between compound 1 and compound 3 to prepare intermediate 2;

   Perform amidation reaction between intermediate 2 and compound 2 to prepare the amide compound;

   Among them, the structures of compound 1, compound 2, compound 3, intermediate 1 and intermediate 2 are as follows:

   
8. A sizing agent, characterized in that its composition includes one or more of the amide compounds shown in any one of claims 1 to 6.
9. A pole piece slurry is characterized in that its composition includes an electrode active material, the sizing agent of claim 8 and a solvent.
10. The pole piece slurry according to claim 9, characterized in that, in the pole piece slurry, the mass percentage of the wetting agent is 0.1% to 0.5%; optionally, the mass percentage of the wetting agent is 0.2%～0.4%.
11. The pole piece slurry according to claim 9 or 10, characterized in that the solvent includes one or more of water, alcoholic solvents and ester solvents; optionally, the alcoholic solvent includes 1 , one or more of 3-propanediol, 1,2-propanediol, 1,4-butanediol and 1,3-butanediol; optionally, the ester solvent includes triethyl phosphate, ethylene carbonate One or more of ester, dimethyl carbonate, diethyl carbonate and propylene carbonate.
12. The pole piece slurry according to any one of claims 9 to 11, characterized in that the pole piece slurry further includes a binder; optionally, the binder includes styrene-butadiene rubber, polyacrylic acid, One or more of sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid and carboxymethyl chitosan, or the binder includes polytetrafluoroethylene, acrylonitrile, Copolymers of one or more of acrylic acid and acrylamide, or copolymers of tetrafluoroethylene and perfluoroalkyl vinyl ether, copolymers of tetrafluoroethylene and hexafluoropropylene and polychlorotrifluoroethylene, ethylene and trifluoroethylene One or more vinyl chloride copolymers.
13. The pole piece slurry according to claim 12, wherein the binder includes a first binder and a second binder;

    Optionally, the first binder includes polytetrafluoroethylene, tetrafluoroethylene and perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene and hexafluoropropylene copolymer and polychlorotrifluoroethylene, ethylene and trifluoroethylene. One or more of the chlorofluoroethylene copolymers, preferably polytetrafluoroethylene; further optionally, the weight average molecular weight of the first binder is greater than 10 million, and the SSG is 2.13 to 2.19; further optionally Preferably, in the pole piece slurry, the mass percentage of the first binder is 0.05% to 0.5%;

    Optionally, the second binder includes one or more copolymers of acrylonitrile, acrylic acid and polyamide; further optionally, the molecular weight of the second binder is greater than 300,000, and the solid content is 4% to 7%; further optionally, the mass percentage of the second binder in the pole piece slurry is 0.5% to 4%.
14. The pole piece slurry according to any one of claims 9 to 13, characterized in that the solid content of the pole piece slurry is 65% to 85%.
15. A method for preparing pole pieces, characterized by comprising the following steps:

    The electrode layer is prepared on the surface of the current collector using the pole piece slurry according to any one of claims 9 to 14.
16. The method of preparing a pole piece according to claim 15, wherein the step of using the pole piece slurry to prepare an electrode layer on the surface of a current collector includes:

    Shape the pole piece slurry to prepare a diaphragm;

    The diaphragm and the current collector are combined.
17. A pole piece, characterized in that it includes a current collector and an electrode layer disposed on the surface of the current collector, and the composition of the electrode layer includes an electrode active material and the wetting agent according to claim 8.
18. The pole piece according to claim 17, characterized in that it has at least one of the following features:

    (1) The mass percentage of the sizing agent is 0.1% to 0.5%; optionally, the mass percentage of the sizing agent is 0.2% to 0.4%;

    (2) The weight of the single-sided film layer of the electrode layer is ≥180mg/1540.25mm ² ; optionally, the weight of the single-sided film layer of the electrode layer is 180mg/1540.25mm ² ~ 250mg/1540.25mm ² .
19. A secondary battery characterized by including the pole piece according to claim 17 or 18.
20. An electrical device, characterized by comprising a secondary battery selected from the group consisting of claim 19.

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