An additive for lithium-ion batteries and its application

Abstract

This application discloses an additive for lithium-ion batteries and its application. The additive has the following raw material composition by weight: 40-70 parts first solvent; 1-10 parts first polymer; 5-15 parts second polymer; 10-20 parts small molecule organic amine; and 10-20 parts stabilizer. The first polymer contains at least one nitrogen-free polar functional group; the second polymer contains at least one nitrogen-containing polar functional group; and the stabilizer is a hydrazine compound. The additive provided in this application, when used in lithium-ion batteries, can solve the problems of thick electrodes easily cracking and the difficulty in dispersing positive electrode particles.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to an additive for lithium-ion batteries and its application. Background Technology

[0002] In existing technologies, an effective way to improve the energy density of lithium-ion batteries is to develop and design thick electrodes. However, thick electrodes have at least two problems: first, they are prone to cracking and have poor mechanical properties; second, it is difficult to disperse nano-sized cathode particles. Summary of the Invention

[0003] Therefore, there is a need to provide an additive that can solve the problems of thick electrodes being prone to cracking and the difficulty in dispersing positive electrode particles.

[0004] An additive for lithium-ion batteries, wherein the raw materials of the additive are composed of the following parts by weight:

[0005]

[0006] The first polymer is at least one of ethyl cellulose, polyvinyl alcohol, polyvinyl butyral, ethylene-vinyl alcohol copolymer, and methyl vinyl ether-maleic anhydride linear copolymer;

[0007] The second polymer is at least one of polyvinylpyrrolidone, hydrogenated nitrile butadiene rubber, polyacrylonitrile, polypyrrole, and styrene-acrylonitrile-acrylic acid copolymer;

[0008] The stabilizer is a hydrazine compound.

[0009] The additives for lithium-ion batteries provided in this application can be used as dispersants for conductive agents in lithium-ion batteries. Adding the additives to the conductive agent can significantly improve the dispersion performance of the conductive agent, reduce the viscosity and fineness of the conductive agent slurry, and reduce the resistivity of the electrode.

[0010] The additives for lithium-ion batteries provided in this application can be applied to the positive electrode slurry process of lithium-ion batteries to increase the viscosity and solid content of the slurry. Due to the increased solid content, the amount of the first solvent evaporating is less during the production of thick electrodes from the slurry, making it less prone to cracking, thereby improving the mechanical properties of the thick electrodes. The additives can effectively promote the dispersion of positive electrode particles. At the same time, the viscosity stability of the positive electrode slurry material is better, improving the coating uniformity.

[0011] The first solvent dissolves the remaining components of the additive and has no other special function. Any commonly used organic first solvent can be used; for example, the first solvent is one of N-methylpyrrolidone (NMP), dimethyl sulfoxide, or dimethylformamide. Preferably, the first solvent is N-methylpyrrolidone.

[0012] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0013] Optionally, the additive has the following composition by weight of raw materials:

[0014]

[0015] Optionally, the additive has the following composition by weight of raw materials:

[0016]

[0017] The first polymer contains at least one nitrogen-free polar functional group, and the first polymer has polyethylene as the main chain. The nitrogen-free polar functional group is one of aldehyde, hydroxyl, carbonyl, or acid anhydride.

[0018] The first polymer contains a polyethylene backbone and polar functional groups such as hydroxyl, carboxyl, aldehyde, and carbonyl groups on the backbone or side chains. Under the action of the polar functional groups, the polymer can dissolve in a first solvent such as NMP. At the same time, the hydrophobic structure of the polyethylene backbone can be adsorbed on the surface of the positive electrode active material or conductive agents such as carbon nanotubes and carbon black. During the positive electrode slurry or conductive agent dispersion process, it can generate steric hindrance to prevent secondary agglomeration of the positive electrode active material or conductive agent, thereby maintaining stable viscosity and reducing the fineness of the slurry.

[0019] Optionally, the first polymer is at least one of ethyl cellulose (e.g., Ashland N7, Ashland N10), polyvinyl alcohol (e.g., Kuraray 3-98; Kuraray 5-98; Kuraray 11-98), polyvinyl butyral (PVB, e.g., Kuraray B30H; Kuraray B60H), ethylene-vinyl alcohol copolymer (e.g., Kuraray G176; Kuraray E105), and methyl vinyl ether-maleic anhydride linear copolymer (e.g., Vantrus ZeMac E60, Vantrus ZeMac E400).

[0020] Optionally, the second polymer is at least one of polyvinylpyrrolidone (PVP, e.g., BASF K17, BASF K30), hydrogenated nitrile butadiene rubber (e.g., Arlanx 4307, Zannan ZNL3403), polyacrylonitrile (weight average molecular weight 80,000 to 100,000), polypyrrole, and styrene-acrylonitrile-acrylic acid copolymer (e.g., Japan UMGS210B).

[0021] The second polymer contains nitrogen-containing polar functional groups, in which nitrogen contains lone pairs of electrons and can form large π bonds with carbon atoms in lithium-ion cathode materials, exhibiting good compatibility and providing an alkaline environment.

[0022] The first polymer and the second polymer preferably have a weight-average molecular weight of 5,000-200,000; more preferably, the weight-average molecular weight is 5,000-50,000. If the molecular weight is too small, it may decompose during the charging and discharging process of the lithium battery, or dissolve in the electrolyte, resulting in gas production or performance degradation of the battery. If the molecular weight is too large, it may cause insolubility in the solvent, or the slurry dispersion viscosity may be high, without a significant effect on reducing viscosity.

[0023] The first polymer is dissolved in NMP, and an NMP solution containing 5% by mass of the first polymer has a viscosity range of 10-1000 mPa·s at 25°C. The second polymer is dissolved in NMP, and an NMP solution containing 5% by mass of the second polymer has a viscosity range of 10-1000 mPa·s at 25°C.

[0024] Optionally, the small molecule organic amine is at least one of diethylenediamine, ethanolamine, isopropanolamine, isobutanolamine, triethanolamine, anhydrous piperazine, and guanidine carbonate.

[0025] The small molecule organic amine is used to adjust the pH value, providing an alkaline environment. It is also highly polar, which allows it to better encapsulate the conductive agent, thereby improving the wettability of the conductive material and making it easier to disperse.

[0026] Optionally, the stabilizer is at least one of hydroxyethyl hydrazine, hydrazine hydrate, and carbazide. Preferably, the stabilizer is hydroxyethyl hydrazine (CAS: 109-84-2). The stabilizer has a hydrazine structure, is highly polar, can provide lone pairs of electrons, adsorbs on the surface of lithium-ion battery cathode particles or carbon particles, increases the polarity of the cathode particles or carbon particles, disperses the particles, and is stable in the first solvent without secondary agglomeration.

[0027] Optionally, the additive has the following composition by weight of raw materials:

[0028]

[0029] Optionally, the additive has the following composition by weight of raw materials:

[0030]

[0031] Optionally, the additive has the following composition by weight of raw materials:

[0032]

[0033] Optionally, the preparation method of the additive includes the following steps:

[0034] The additive is obtained by uniformly mixing a small molecule organic amine, a stabilizer, a first polymer solution, and a second polymer solution at a temperature below 50°C, wherein the first polymer solution and the second polymer solution are obtained by any of the following methods:

[0035] a) Divide the first solvent into two portions, dissolve the first polymer in one portion to obtain a first polymer solution, and dissolve the second polymer in the other portion to obtain a second polymer solution;

[0036] b) The first polymer and the second polymer are added to the same first solvent in any order to dissolve them, thereby obtaining a first polymer solution and a second polymer solution.

[0037] In cases where the same first solvent is used for dissolution, the second polymer is added only after the first polymer has been fully dissolved.

[0038] Optionally, the preparation method of the additive includes the following steps:

[0039] The first polymer is dissolved in the first solvent to obtain a first polymer solution;

[0040] The second polymer is dissolved in the first solvent to obtain a solution of the second polymer;

[0041] The additive is obtained by mixing small molecule organic amine, stabilizer, first polymer solution and second polymer solution uniformly at a temperature below 50°C.

[0042] Since there are many different polymer options for the first and second polymers, for polymers that require high-temperature dissolution (e.g., polyvinyl alcohol, ethylene-vinyl alcohol copolymer, methyl vinyl ether-maleic anhydride linear copolymer, hydrogenated nitrile rubber, polypyrrole, and styrene-acrylonitrile-acrylic acid copolymer), dissolution is carried out at 80-100°C under nitrogen protection (the dissolution time is selected according to actual needs, for example, 4-8 hours). After dissolution, the temperature needs to be cooled to below 50°C before mixing with other components.

[0043] For polymers that do not require high-temperature dissolution (e.g., ethyl cellulose, polyvinylpyrrolidone, polyvinyl butyral), dissolve for 0.5–2 hours under nitrogen protection.

[0044] All components are mixed evenly under stirring conditions for 0.5 to 2 hours.

[0045] This application also provides an application of the additive described herein in a conductive agent.

[0046] A conductive agent includes: a second solvent, a conductive material, and the additive, wherein the amount of the additive is 10-20% of the mass of the conductive material.

[0047] The second solvent can be a commonly used solvent for conductive agents, such as N-methylpyrrolidone (NMP) or dimethylformamide (DMF).

[0048] The conductive material is at least one of carbon nanotubes, graphene, carbon black, Ketjen black, and carbon nanofiber (VGCF).

[0049] The fineness of the conductive agent slurry scraper is 10-15 μm.

[0050] The resistivity of the conductive agent film is 14–16 mΩ·cm.

[0051] The slurry viscosity of the conductive agent is 400–550 mPa·s.

[0052] This application also provides the application of the additive described herein in lithium-ion battery cathode slurry.

[0053] A lithium-ion battery positive electrode slurry, with the following raw material composition by weight:

[0054]

[0055] The second solvent is a component of the conductive agent, and the third solvent is a component of the lithium-ion battery positive electrode slurry. The first solvent, the second solvent, and the third solvent each have their own meanings. These three solvents can be the same or different solvents.

[0056] The third solvent can be N-methylpyrrolidone (NMP), dimethylformamide (DMF), or other commonly used solvents in cathode slurries.

[0057] The viscosity of the lithium-ion battery cathode slurry after 24 hours of storage is less than 12000 mPa·s.

[0058] The viscosity of the lithium-ion battery cathode slurry after 24 hours of storage is less than 12000 mPa·s and greater than 9000 mPa·s. Unless otherwise specified in this application, viscosity refers to viscosity at 25°C.

[0059] The solid content of the lithium-ion battery cathode slurry is greater than 65%.

[0060] The solid content of the lithium-ion battery cathode slurry is greater than 65% and less than 70%.

[0061] Adding additives to the cathode slurry of lithium-ion batteries can effectively promote the dispersion of nano-sized lithium iron phosphate and conductive agents, effectively reduce the viscosity of the cathode slurry, and increase the solid content in the cathode slurry by at least 6% at the same viscosity level, thereby improving efficiency, reducing consumption, preventing cracking, and improving the viscosity stability of the cathode slurry, thus enhancing the coating uniformity.

[0062] The additive provided in this application has at least the following beneficial effects:

[0063] (1) It is used as a dispersant in the dispersion process of conductive agents such as carbon nanotubes, graphene and carbon black. The amount used is 10% to 20% of the mass of the conductive agent. It can significantly improve the dispersion degree of the conductive agent, reduce the viscosity of the conductive agent slurry, the fineness of the conductive agent slurry and the resistivity of the conductive agent after it is made into an electrode.

[0064] (2) In the process of lithium iron phosphate cathode slurry, after adding PVDF solution and conductive agent, add additives. The amount of additives added is 0.1-0.5% of the mass of lithium iron phosphate cathode. This can significantly increase the solid content of cathode slurry and reduce the viscosity of slurry. Attached Figure Description

[0065] Figure 1a A scraper fineness diagram for the additive prepared in Example 1 applied to a conductive agent;

[0066] Figure 1b The scraper fineness diagram shows the application of the additive prepared in Example 2 into the conductive agent.

[0067] Figure 1c A scraper fineness diagram for the additive prepared in Example 3 applied to a conductive agent;

[0068] Figure 2a The scraper fineness diagram for the application of the additive prepared in Comparative Example 1 in a conductive agent;

[0069] Figure 2b The scraper fineness diagram for the application of the additive prepared in Comparative Example 2 in a conductive agent;

[0070] Figure 2c The scraper fineness diagram for the application of the additive prepared in Comparative Example 3 in a conductive agent;

[0071] Figure 3a The graph shows the particle size test results of the additive prepared in Example 1 applied to a conductive agent.

[0072] Figure 3b The graph shows the particle size test results of the additive prepared in Example 2 applied to the conductive agent.

[0073] Figure 3cThe graph shows the particle size test results of the additive prepared in Example 3 applied to the conductive agent.

[0074] Figure 4a The particle size test results of the additive prepared in Comparative Example 1 applied to the conductive agent are shown in the figure.

[0075] Figure 4b The particle size test results are shown for the additive prepared in Comparative Example 2 when applied to a conductive agent.

[0076] Figure 4c The graph shows the particle size test results of the additive prepared in Comparative Example 3 when applied to a conductive agent.

[0077] Figure 5a Electrochemical performance test graph for reference example;

[0078] Figure 5b Electrochemical performance test diagram of the additive prepared in Example 1 applied to the positive electrode slurry;

[0079] Figure 6 This is an AC internal resistance (ACIR) test graph, where the horizontal axis represents the number of battery packs.

[0080] Figure 7 This is a test graph of battery voltage, with the horizontal axis representing the number of battery packs.

[0081] Figure 8 This is a test graph for DC internal resistance (DCIR), with the horizontal axis representing the number of battery packs. Detailed Implementation

[0082] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0083] To better describe and illustrate the embodiments of this application, reference may be made to one or more accompanying drawings, but the additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the inventive creations of this application, the embodiments or preferred methods described herein.

[0084] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0085] Example 1

[0086] Using N-methylpyrrolidone (NMP) as the first solvent, 56 parts (by weight, the same applies to other raw materials) of NMP were weighed. Under nitrogen protection at 100°C, 2.4 parts of ethyl cellulose (i.e., the first polymer, specifically Ashland N7, with a viscosity of 50 cPs, which is the viscosity of an 8% NMP solution of ethyl cellulose at 25°C) were added to the first solvent. After dissolving for 2 hours, the temperature was lowered to below 50°C, and then 9.6 parts of polyvinylpyrrolidone (i.e., the second polymer, specifically BASF K10, with a viscosity of 15 cPs, which is the viscosity of an 8% NMP solution of polyvinylpyrrolidone at 25°C) were added. After dissolving for 1 hour, 16 parts of isobutanolamine (i.e., a small molecule organic amine) and 16 parts of hydroxyethyl hydrazine (i.e., a stabilizer) were added. The mixture was stirred at 1200 rpm for 1 hour to obtain the additive.

[0087] Example 2

[0088] Using N-methylpyrrolidone (NMP) as the first solvent, weigh 56 parts of NMP (by weight; other raw materials are handled similarly). Under nitrogen protection at 80°C, add 9.6 parts of hydrogenated nitrile butadiene rubber (i.e., the second polymer, specifically Arlanx 4307, whose viscosity is 800 cPs, the viscosity of a 6% (by mass) NMP solution of hydrogenated nitrile butadiene rubber at 25°C) and 1.2 parts of ethylene-vinyl alcohol copolymer (i.e., the first polymer, specifically Kuraray G176, whose viscosity is 100 cPs). The viscosity of the NMP solution of 3% ethylene-vinyl alcohol copolymer (at 25°C) was continuously dissolved for 2 hours. Then, the temperature was lowered to below 50°C, and 1.2 parts of polyvinyl butyral (i.e., the first polymer, specifically Kuraray B60H, whose viscosity is 20 cPs, which is the viscosity of the NMP solution of 3% polyvinyl butyral at 25°C) were added. After dissolving for 1 hour, 16 parts of isobutanolamine (i.e., a small molecule organic amine) and 16 parts of hydroxyethyl hydrazine (i.e., a stabilizer) were added. The mixture was stirred at 1200 rpm for 1 hour to obtain the additive.

[0089] Example 3

[0090] Using N-methylpyrrolidone (NMP) as the first solvent, 50 parts (by weight, the same applies to other raw materials) of NMP were weighed. Under nitrogen protection at 80°C, 15 parts of polypyrrole (i.e., the second polymer, with a viscosity of 100 cPs, the viscosity of a 3% NMP solution of polypyrrole at 25°C) were added to the first solvent. After dissolving for 2 hours, the temperature was lowered to below 50°C, and then 2 parts of polyvinyl butyral (i.e., the first polymer, specifically Kuraray B60H, with a viscosity of 20 cPs, the viscosity of a 3% NMP solution of polyvinyl butyral at 25°C) were added. After dissolving for 1 hour, 16 parts of isopropanolamine (i.e., a small molecule organic amine) and 16 parts of hydroxyethyl hydrazine (i.e., a stabilizer) were added. The mixture was stirred at 1200 rpm for 1 hour to obtain the additive.

[0091] Comparative Example 1 without polymer

[0092] Using N-methylpyrrolidone (NMP) as solvent, 68 parts of NMP were weighed, and 16 parts of isobutanolamine and 16 parts of hydroxyethylhydrazine were added. The mixture was stirred at 1200 rpm for 1 hour to obtain the additive.

[0093] Comparative Example 2 without organic amines and stabilizers

[0094] Using N-methylpyrrolidone (NMP) as a solvent, 72 parts of NMP were weighed and added to the solvent at 100°C under nitrogen protection. 2.4 parts of ethyl cellulose (the same substance as in Example 1) were added and dissolved for 2 hours. The temperature was then lowered to below 50°C, and then 9.6 parts of polyvinylpyrrolidone (the same substance as in Example 1) were added and dissolved for 1 hour to obtain the additive.

[0095] Comparative Example 3 without stabilizer

[0096] Using N-methylpyrrolidone (NMP) as a solvent, 56 parts of NMP were weighed and added to the solvent at 100°C under nitrogen protection. 2.4 parts of ethyl cellulose (same as in Example 1) were added and dissolved for 2 hours. After cooling to below 50°C, 9.6 parts of polyvinylpyrrolidone (same as in Example 1) were added and dissolved for 1 hour. Then, 32 parts of isopropanolamine were added and stirred at 1200 rpm for 1 hour to obtain the additive.

[0097] Application Example 1: Application in Conductive Agents

[0098] 89.3 parts of N-methylpyrrolidone (NMP) were weighed, and 6.7 parts of additives were added. After mixing evenly, 5 parts of 5-10 nm multi-walled carbon nanotubes were added, and the mixture was ground and dispersed at a dispersion linear velocity of 15 m / s. After uniform dispersion, the viscosity, scraper fineness, particle size, and film resistance were tested. The test results of the additives prepared in each example and comparative example applied to conductive agents are shown in Table 1.

[0099] Table 1

[0100]

[0101] As shown in Table 1, the conductive agent slurry with additives from Examples 1 to 3 has a lower viscosity than the conductive agent slurry with additives from Comparative Examples 1 to 3.

[0102] For details of the scraper fineness diagrams in Examples 1-3, please refer to... Figures 1a to 1c As shown, the fineness diagrams of scrapers for comparative examples 1-3 are detailed below. Figures 2a-2c As shown in the figures and the data in Table 1, the conductive agent slurry with additives from Examples 1 to 3 has a finer particle size.

[0103] As shown in Table 1, the resistivity of the conductive agent slurry with additives from Examples 1 to 3 is lower than that of the conductive agent slurry with additives from Comparative Examples 1 to 3.

[0104] The conductive agent slurry has lower viscosity, finer particle size, and lower resistivity, which proves that the addition of additives can effectively improve the dispersion performance of the conductive agent.

[0105] Application Example 2: Application in Positive Electrode Slurry

[0106] The positive electrode slurry was prepared according to the ratio of lithium iron phosphate: carbon black: PVDF binder: additive: NMP = 97:1:2.5:0.2:43.67. After the positive electrode slurry was prepared, the viscosity was tested at the initial stage, after 2 hours, 4 hours, 8 hours and 24 hours. The viscosity and membrane resistance were also tested, and the results are shown in Table 2.

[0107] In Table 2, no additives were added in the reference examples.

[0108] Table 2

[0109]

[0110]

[0111] The CV curve of the positive electrode slurry prepared according to the reference example is as follows: Figure 5a As shown, the positive electrode slurry prepared with the additives in Example 1 is as follows: Figure 5b As shown, there is no significant difference in electrochemical performance between the battery with and without additives. The additive remains stable at voltages above 4.5V without decomposition and exhibits no obvious redox peaks, indicating that the additive is stable in the battery, does not cause side reactions, and can be used in high-voltage systems.

[0112] As shown in Table 2, after adding the additives prepared in each embodiment, the viscosity of the positive electrode slurry decreased significantly, and the membrane resistivity decreased slightly. This indicates that the viscosity of the positive electrode slurry can be reduced by introducing the additives, thus effectively increasing the content of effective components, reducing the amount of the third solvent used, improving the electrode baking efficiency, enabling the fabrication of thick electrodes, and preventing electrode cracking. Meanwhile, the membrane resistivity remained essentially the same as without the additives, indicating that the introduction of the additives does not affect the battery's internal resistance. Although this additive is non-conductive, it helps disperse the positive electrode and conductive agent, thus improving the overall battery performance.

[0113] Battery performance characterization

[0114] Configure the positive electrode slurry according to the data shown in Table 3, fabricate the battery cell, and test the AC internal resistance, plateau voltage, and DC internal resistance.

[0115] Table 3

[0116]

[0117]

[0118] The weight ratio of the 280 lithium iron phosphate cathode slurry is: lithium iron phosphate: carbon black: PVDF binder: NMP = 97:1:2.5:43.67.

[0119] In Experiment 2, 0.2% of the additive prepared in Comparative Example 1 was added, meaning the amount of additive prepared in Comparative Example 1 added was 0.2% of the mass of lithium iron phosphate. Similarly, in Experiment 3, 0.03% of the additive prepared in Example 1 was added, meaning the amount of additive prepared in Example 1 added was 0.03% of the mass of lithium iron phosphate.

[0120] As shown in Table 3, the solid content of Experiment 3 was increased to 66.6%, and the slurry viscosity of Experiment 3 was reduced to 4010 MPa.s.

[0121] During the electrode coating process, none of the three positive electrode slurries prepared in Experiment 1, Experiment 2, and Experiment 3 showed obvious abnormalities such as particles or scratches, and no abnormalities such as broken strips or wrinkles were observed during rolling.

[0122] See Figure 6 As shown, in Experiment 2, the AC internal resistance of the battery cell increased after adding the additive prepared in Comparative Example 1, while in Experiment 3, the AC internal resistance of the battery cell decreased by more than 30% after adding the additive prepared in Example 1.

[0123] See Figure 7 As shown, the voltage of the capacity grading platform in Experiments 2 and 3 increased by about 5%, while the voltage of the capacity grading platform in Experiment 1 was lower.

[0124] See Figure 8As shown, after adding the additive prepared in Example 1 in Experiment 3, the DC internal resistance of the battery cell decreased by nearly 50%.

[0125] The test results of the standard charge-discharge energy retention rate (1P / 0.5P; 2P / 0.5P) of Experiment 1, Experiment 2 and Experiment 3 are shown in Tables 4 and 5. In Experiment 3, after adding the additive prepared in the example, the 0.5P voltage plateau and 2P charging energy retention rate of the battery were significantly improved.

[0126] Table 4

[0127]

[0128] Table 5

[0129]

[0130]

[0131] The test results of the standard charge-discharge energy retention rate (1P / 0.5P; 2P / 0.5P) of Experiment 1, Experiment 2 and Experiment 3 are shown in Table 6 and Table 7. In Experiment 3, after adding the additive prepared in the example, the battery platform voltage and the charge-discharge energy efficiency of 1P and 2P were significantly improved.

[0132] Table 6

[0133]

[0134]

[0135] Table 7

[0136]

[0137]

[0138] As shown in Table 8, the high-temperature charge-discharge performance of batteries in Experiment 1, Experiment 2 and Experiment 3 is basically the same.

[0139] Table 8

[0140]

[0141]

[0142] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0143] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An additive for lithium-ion batteries, characterized in that, The raw material composition of the additive is as follows by weight: First solvent 40~70; First polymers 1~10; Second polymer 5~15; 10-20 small molecule organic amines; Stabilizer 10~20; The first polymer contains at least one nitrogen-free polar functional group, and the first polymer is at least one of ethyl cellulose, polyvinyl alcohol, polyvinyl butyral, ethylene-vinyl alcohol copolymer, and methyl vinyl ether-maleic anhydride linear copolymer. The second polymer has nitrogen-containing polar functional groups, and the second polymer is at least one of polyvinylpyrrolidone, hydrogenated nitrile rubber, polyacrylonitrile, polypyrrole, and styrene-acrylonitrile-acrylic acid copolymer; The small molecule organic amine is at least one of diethylenediamine, ethanolamine, isopropanolamine, isobutanolamine, triethanolamine, and anhydrous piperazine; The stabilizer is at least one of hydroxyethyl hydrazine, hydrazine hydrate, and carbazide.

2. The additive for lithium-ion batteries as described in claim 1, characterized in that, The raw material composition of the additive is as follows by weight: First solvent 56; Ethyl cellulose 1~5; Polyvinylpyrrolidone 5~10; Isobutanolamine 15~20; Hydroxyethylhydrazine 15~20.

3. The additive for lithium-ion batteries as described in claim 1, characterized in that, The raw material composition of the additive is as follows by weight: First solvent 56; 1-2 ethylene-vinyl alcohol copolymers; Polyvinyl butyral 1~2; Hydrogenated nitrile butadiene rubber 5~10; Isobutanolamine 15~20; Hydroxyethylhydrazine 15~20.

4. The additive for lithium-ion batteries as described in claim 1, characterized in that, The raw material composition of the additive is as follows by weight: First solvent 56; Polyvinyl butyral 1~5; Polypyrrole 10~15; Isopropanolamine 15~20; Hydroxyethylhydrazine 15~20.

5. The additive for lithium-ion batteries as described in claim 1, characterized in that, Includes the following steps: The additive is obtained by uniformly mixing a small molecule organic amine, a stabilizer, a first polymer solution, and a second polymer solution at a temperature below 50°C, wherein the first polymer solution and the second polymer solution are obtained by any of the following methods: a) Divide the first solvent into two portions, dissolve the first polymer in one portion to obtain a first polymer solution, and dissolve the second polymer in the other portion to obtain a second polymer solution; b) The first polymer and the second polymer are added to the same first solvent in any order to dissolve them, thereby obtaining a first polymer solution and a second polymer solution.

6. The additive for lithium-ion batteries as described in claim 5, characterized in that, The small molecule organic amine, stabilizer, first polymer solution, and second polymer solution are mixed evenly under stirring conditions for 0.5 to 2 hours.

7. The use of the additive as described in any one of claims 1 to 6 in a conductive agent.

8. The application of the additive as described in any one of claims 1 to 6 in lithium-ion battery cathode slurry.

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