A suspending agent for anode slurry, a preparation method thereof, and application thereof

Abstract

The present application provides a kind of suspension agent for anode slurry, with structure shown in formula I.The carbonyl in the suspension agent provided by the present application and the hydroxyl on the surface of graphite form hydrogen bond, meanwhile the lone pair of electrons on the suspension agent S is negatively charged, can and other negatively charged molecules such as hydroxyl in water mutually repel, the suspension agent and graphite are combined together by hydrogen bond, water molecules (in which there is negatively charged hydroxyl) constantly repel and impact the graphite and suspension agent (with lone pair of electrons on S negatively charged) combined together, reduce the settlement of graphite by Brownian motion, graphite and a large number of water repel each other and are in motion process and will not settle, increase the suspension stability of graphite particles, and further improve the battery capacity.The suspension agent contains hydroxyl hydrophilic group, and is easy to dissolve in water.

Description

Technical Field

[0001] This invention belongs to the field of power battery technology, specifically relating to a suspending agent for anode slurry, its preparation method, and its application. Background Technology

[0002] Industry experts analyze that the supply shortage of power batteries is largely due to the rapid development of new energy vehicle production, which has caused a lag in the response of the entire power battery industry chain. Insufficient power battery production capacity has restricted the production of new energy vehicles by automakers. Facing the production and sales plans for new energy vehicles in the new year, finding power battery manufacturers that can meet their production capacity needs is a top priority for automakers. However, for power battery manufacturers, increasing production capacity is the key.

[0003] Anode graphite is oily and has poor compatibility with aqueous deionized water, leading to persistent sedimentation problems in the anode slurry, which severely affect its stability and coating performance. Therefore, there is an urgent need to find a method to improve slurry sedimentation and thus coating stability, thereby increasing battery production capacity without degrading battery performance, in order to meet the development needs of new energy vehicles. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a suspending agent for anode slurry, its preparation method and application. The suspending agent for anode slurry provided by the present invention can improve slurry sedimentation and thus improve coating stability, thereby increasing battery production capacity.

[0005] This invention provides a suspending agent for anode slurry, characterized in that it has the structure shown in Formula I:

[0006]

[0007] The present invention also provides a method for preparing the above-mentioned suspending agent for anode slurry, comprising the following steps:

[0008] 6-Bromo-2-isobutylonethioran reacts with a weak alkaline solution to form 6-hydroxy-2-isobutylonethioran.

[0009] Preferably, the weak base is selected from ammonia water, sodium bicarbonate solution, and sodium carbonate solution.

[0010] Preferably, the 6-bromo-2-isobutylonethioran is prepared according to the following method:

[0011] A) Thian and 1-chloro-2-methyl-propanol were mixed and subjected to a nucleophilic substitution reaction to give 2-isobutyranol;

[0012] B) 2-Isobutanolthiaran was reacted in the presence of a catalyst to obtain 2-isobutanonethiaran;

[0013] C) The 2-isobutyranone was reacted with pure bromine in the presence of a catalyst to give 6-bromo-2-isobutyranone.

[0014] Preferably, in step A), the molar ratio of the thioran to 1-chloro-2-methyl-propanol is 1:1 to 1:3;

[0015] The nucleophilic substitution reaction is carried out in the presence of a weak base solution and an alcohol solution, wherein the weak base is selected from ammonia water, sodium bicarbonate solution and sodium carbonate solution, and the alcohol solution is selected from ethanol, propanol or butanediol.

[0016] The nucleophilic substitution reaction was carried out at a temperature of 60–65 °C for 28–34 h.

[0017] Preferably, in step B), the catalyst is selected from chromium trioxide, and the reaction temperature is 21–25°C.

[0018] Preferably, in step C), the molar ratio of 2-isobutylonethioran to pure bromine is 1:2 to 1:3;

[0019] The catalyst is selected from ferric tribromide;

[0020] The substitution reaction was carried out at a temperature of 21–25°C for 18–20 hours.

[0021] The present invention also provides an anode slurry, wherein the solid raw materials in the anode slurry include a negative electrode active material, a conductive agent, a dispersant and a binder, and the anode slurry further includes a suspending agent selected from the above-mentioned suspending agents for anode slurries.

[0022] Preferably, the solid raw materials in the anode slurry include:

[0023] 95%–98% of the negative electrode active material;

[0024] 0.06% to 2% conductive agent;

[0025] 1.3% to 1.5% dispersant;

[0026] 1% to 3% adhesive;

[0027] The amount of the suspending agent is 0.12% to 0.18% of the total amount of solid raw materials in the anode slurry.

[0028] The present invention also provides a lithium-ion battery comprising the above-mentioned suspending agent for the anode slurry.

[0029] Compared with existing technologies, this invention provides a suspending agent for anode slurry, having the structure shown in Formula I. In the suspending agent provided by this invention, the carbonyl group forms hydrogen bonds with the hydroxyl groups on the graphite surface. Simultaneously, the lone pair electrons on the suspending agent S carry a negative charge, which can repel other negatively charged molecules such as hydroxide ions in water. The suspending agent and graphite are bound together by hydrogen bonds. Water molecules (containing negatively charged hydroxide ions) continuously repel and collide with the bound graphite and suspending agent (S has a negatively charged lone pair electron), reducing graphite sedimentation through Brownian motion. The graphite and a large amount of water repel each other and remain in motion, preventing sedimentation, thus increasing the suspension stability of graphite particles and thereby improving battery capacity. Furthermore, this suspending agent contains hydrophilic hydroxyl groups, making it readily soluble in water. Attached Figure Description

[0030] Figure 1 This is a diagram illustrating the reaction mechanism of the suspending agent in the anode slurry provided by the present invention.

[0031] Figure 2 The results show the kinetic instability test results for different types of slurries. Detailed Implementation

[0032] This invention provides a suspending agent for anode slurry, having the structure shown in Formula I:

[0033]

[0034] In this invention, the method for preparing the suspending agent for the anode slurry includes the following steps:

[0035] 6-Bromo-2-isobutylonethioran reacts with a weakly alkaline solution to form a compound with the structure shown in Formula I, namely 6-hydroxy-2-isobutylonethioran.

[0036] The weak base is selected from one of ammonia water, sodium bicarbonate solution and sodium carbonate solution.

[0037] In this invention, the structural formula of 6-bromo-2-isobutylonethioran is as follows:

[0038]

[0039] The 6-bromo-2-isobutylone thioran was prepared according to the following method:

[0040] A) Thian and 1-chloro-2-methyl-propanol were mixed and subjected to a nucleophilic substitution reaction to give 2-isobutyranol;

[0041] B) 2-Isobutanolthiaran was reacted in the presence of a catalyst to obtain 2-isobutanonethiaran;

[0042] C) The 2-isobutyranone was reacted with pure bromine in the presence of a catalyst to give 6-bromo-2-isobutyranone.

[0043] Specifically, in this invention, thiaran and 1-chloro-2-methyl-propanol are first mixed, and a nucleophilic substitution reaction is carried out in the presence of a weak base and an alcohol solution. The sulfur atom has a lone pair of electrons, which repel each other, increasing the electron cloud density at position 2, thus initiating the nucleophilic substitution reaction.

[0044] The weak base is selected from one of ammonia water, sodium bicarbonate solution and sodium carbonate solution, and the alcohol solution is selected from one of ethanol, propanol or butanediol.

[0045] The molar ratio of thioran and 1-chloro-2-methyl-propanol is 1:1 to 1:3, preferably 1:1, 1:2, 1:3, or any value between 1:1 and 1:3.

[0046] The nucleophilic substitution reaction is carried out at a temperature of 60–65°C, preferably 60, 61, 62, 63, 64, or 65°C, or any value between 60 and 65°C, and for a time of 28–34 h, preferably 28, 30, 32, or 34 h, or any value between 28 and 34 h.

[0047] The specific reaction formula is as follows:

[0048]

[0049] Next, 2-isobutyran was reacted in the presence of a catalyst to obtain 2-isobutyranone.

[0050] The catalyst is selected from chromium trioxide, and the reaction temperature is 21-25℃.

[0051] The specific reaction formula is as follows:

[0052]

[0053] After obtaining 2-isobutyranone, the 2-isobutyranone was reacted with pure bromine in the presence of a catalyst to undergo a substitution reaction, yielding 6-bromo-2-isobutyranone. The sulfur atom has a lone pair of electrons, which repel each other, increasing the electron cloud density at position 2, thus triggering the substitution reaction first.

[0054] The molar ratio of 2-isobutylonethioran to pure bromine is 1:2 to 1:3.

[0055] The catalyst is selected from ferric tribromide;

[0056] The temperature of the substitution reaction is 21–25°C, preferably 21, 22, 23, 24, 25°C, or any value between 21 and 25°C, and the time is 18–20 h, preferably 18, 19, 20 h, or any value between 18 and 20 h.

[0057] The specific reaction formula is as follows:

[0058]

[0059] The present invention also provides an anode slurry, comprising a negative electrode active material, a conductive agent, a dispersant and a binder, wherein the anode slurry further comprises a suspending agent selected from the above-mentioned suspending agents for anode slurries.

[0060] In some specific embodiments of the present invention, the anode slurry comprises the following raw materials by mass percentage:

[0061] 95%–98% of the negative electrode active material;

[0062] 0.06% to 2% conductive agent;

[0063] 1.3% to 1.5% dispersant;

[0064] 1% to 3% adhesive;

[0065] The amount of the suspending agent is 0.12% to 0.18% of the total amount of solid raw materials in the anode slurry.

[0066] The anode slurry provided by this invention comprises 95% to 98% of anode active material, preferably 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, or any value between 95% and 98%. In this invention, the anode active material is selected from graphite, including but not limited to artificial graphite, natural graphite, and one or more of the intermediate carbon microspheres.

[0067] The anode slurry provided by this invention further includes 0.06% to 2% of a conductive agent, preferably 0.06%, 0.08%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, or any value between 0.06% and 2%. In this invention, the conductive agent is selected from one or more of conductive carbon and single-walled carbon nanotubes.

[0068] The anode slurry provided by the present invention further includes 1.3% to 1.5% of a dispersant, preferably 1.3%, 1.35%, 1.4%, 1.45%, 1.5%, or any value between 1.3% and 1.5%. The binder is selected from CMC.

[0069] The anode slurry provided by the present invention further includes 1% to 3% of a binder, preferably 1%, 1.2%, 1.3%, 1.5%, 1.7%, 1.9%, 2%, 2.1%, 2.3%, 2.5%, 2.7%, 2.9%, 3%, or any value between 1% and 3%. The binder is selected from styrene-butadiene rubber.

[0070] In this invention, the solvent used to disperse the anode slurry is deionized water, and the amount of solvent added makes the solid content of the slurry 65% ​​to 69%, preferably 65%, 66%, 67%, 68%, 69%, or any value between 65% and 69%.

[0071] The anode slurry provided by the present invention further includes a suspending agent, the amount of which accounts for 0.12% to 0.18% of the total amount of solid raw materials in the anode slurry. Preferably, it is 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, or any value between 0.12% and 0.18%.

[0072] The present invention also provides a negative electrode sheet, comprising a negative current collector and a membrane composited on the surface of the negative current collector, wherein the membrane is obtained by coating the surface of the negative current collector with an anode slurry and then drying it.

[0073] The present invention also provides a lithium-ion battery comprising the above-mentioned suspending agent for the anode slurry.

[0074] The suspending agent provided by this invention forms hydrogen bonds between the carbonyl groups and the hydroxyl groups on the graphite surface. Simultaneously, the lone pair electrons on the suspending agent S carry a negative charge, which can repel other negatively charged molecules such as hydroxyl ions in water. The suspending agent and graphite are bound together by hydrogen bonds. Water molecules (containing negatively charged hydroxyl ions) continuously repel and collide with the bound graphite and suspending agent (S with negatively charged lone pairs of electrons), reducing graphite sedimentation through Brownian motion. The graphite and a large amount of water repel each other and remain in motion, preventing sedimentation, thus increasing the suspension stability of graphite particles and improving battery capacity. Furthermore, this suspending agent contains hydrophilic hydroxyl groups, making it readily soluble in water. See also Figure 1 , Figure 1 The reaction mechanism diagram of the suspending agent in the anode slurry provided by the present invention is shown.

[0075] To further understand the present invention, the following embodiments illustrate the suspending agent for anode slurry provided by the present invention, its preparation method, and its application. The scope of protection of the present invention is not limited by the following embodiments.

[0076] Example 1

[0077] 1) Thian and 1-chloro-2-methyl-propanol in a molar ratio of 1:1 undergo a nucleophilic substitution reaction in a solution of 45% ammonia and 55% ethanol in a volume ratio of 1:2 to produce 2-isobutyranthian.

[0078] 2) 2-Isobutyran reacts at 21–25 °C under chromium trioxide catalysis. The hydroxyl group and the hydrogen atom at the ortho-CH position in 2-isobutyran lose one hydrogen molecule to form 2-isobutyranone.

[0079] 3) 2-Isobutanonethioran in a molar ratio of 1:3 reacts with pure bromine in the presence of ferric bromide to produce 6-bromo-2-isobutanonethioran;

[0080] 4) 6-Bromo-2-isobutylonethioran reacts with 55% sodium bicarbonate solution to form 6-hydroxy-2-isobutylonethioran.

[0081] Example 2

[0082] 1. Slurry preparation

[0083] Add the negative electrode active material to the mixing tank, then add the conductive agent, deionized water and CMC and stir (the CMC is dispersed in a solvent before stirring). After stirring, add the suspending agent and binder prepared in Example 1 and disperse at high speed to obtain a slurry.

[0084] The mass ratio of negative electrode active material / artificial graphite, conductive agent / carbon black, CMC and binder / styrene-butadiene rubber is 96.2:1:1.3:1.5.

[0085] The amount of deionized water added is such that the solid content of the slurry is 48%. The solid content of the slurry is the percentage of the total mass of the negative electrode active material, conductive agent, CMC, styrene-butadiene rubber, and suspending agent in the slurry mass.

[0086] Table 1. Slurry Formulation Table

[0087] A / 48％ B 0.10％ 48％ C 0.12％ 48％ D 0.16％ 48％ E 0.18％ 48％ F 0.2％ 48％

[0088] In Table 1, the amount of suspending agent prepared in Example 1 represents the percentage by mass of the amount of suspending agent prepared in Example 1 relative to the total content of negative electrode active material, conductive agent, CMC and styrene-butadiene rubber in the slurry.

[0089] Among them, groups B to F are: when the total content of negative electrode active material, conductive agent, CMC and styrene-butadiene rubber in the slurry is the same, in order to ensure that the solid content of the slurry remains unchanged, the amount of water added to the slurry increases accordingly with the increase of the amount of suspending agent. The increased amount of water can increase the probability of repulsion and collision between graphite and suspending agent, reduce the sedimentation of graphite through Brownian motion, and the graphite and a large amount of water repel each other and are always in motion without settling, thereby increasing the suspension stability of graphite particles and thus improving battery production capacity.

[0090] 2. Slurry performance testing

[0091] (1) Slurry stability index corresponding to different types of slurry viscosity.

[0092] Table 2

[0093]

[0094]

[0095] The slurry stability standard is TSI<1.

[0096] The viscosity range is 2000-8000 mPa·s. Within this range, the slurry instability can be measured after removal from the pot. Slurry instability should not be left for too long; generally, it should be measured after 8-10 hours. In Scheme A, no suspending agent was added during stirring, resulting in a slurry instability TSI of 3.25. In Scheme B, the addition ratio was lower than the range, leading to higher slurry instability. In Scheme CE, different proportions of suspending agent were added during stirring; the slurry instability gradually decreased with increasing addition ratio, and lower was better. When the additive addition exceeded 0.2%, the slurry instability increased to 1.02. The addition ratio should be controlled between 0.12% and 0.18% of the total amount; exceeding this ratio will affect performance, while falling below it will cause cracking.

[0097] (2) Kinetic instability of slurry

[0098] The testing principle is based on the absorption characteristics and degree of absorption of substances in the ultraviolet and visible spectral regions, a method of qualitative analysis. The concentration (volume percentage) and average diameter (or average diameter of particles / droplets / bubbles) of the dispersed phase determine the intensity of transmitted and backscattered light obtained by the light source detector. The ratio of transmitted to backscattered light intensities can be used to qualitatively analyze the particle size of the slurry. During testing, the sample is placed in a photometer and absorbed into a beam of light of a specific wavelength. Based on the light intensity absorbed by the sample, the absorbance is calculated, thereby calculating the change in slurry particle size over time. The stability of the slurry is then assessed by observing the change in particle size.

[0099] See results Figure 2 , Figure 2 The results are from tests on the kinetic instability of different types of slurries. Figure 2It can be seen that Scheme A, without adding a suspending agent during stirring, has a slurry instability TSI of 3.25 and a relatively high viscosity of around 5000 mPa·s. Scheme B, with an addition ratio below the range, also exhibits high slurry instability. Scheme CE, with the addition of different proportions of suspending agent during stirring, shows that the slurry instability gradually decreases with increasing addition ratio, and lower is better. When the additive addition exceeds 0.2%, the slurry instability increases to 1.02, and the viscosity also increases to around 2800 mPa·s. The addition ratio should be controlled between 0.12% and 0.18% of the total amount; exceeding this ratio will affect performance, while falling below it will cause cracking.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An anode slurry, characterized in that, The solid raw materials in the anode slurry include a negative electrode active material, a conductive agent, a dispersant, and a binder. The negative electrode active material is graphite. The anode slurry also includes a suspending agent, which has the structure shown in Formula I. Equation I; The amount of the suspending agent is 0.12% to 0.18% of the total amount of solid raw materials in the anode slurry.

2. The anode slurry according to claim 1, characterized in that, The method for preparing the suspending agent includes the following steps: 6-Bromo-2-isobutylonethioran reacts with a weak alkaline solution to form 6-hydroxy-2-isobutylonethioran.

3. The anode slurry according to claim 2, characterized in that, The weak base is selected from one of ammonia water, sodium bicarbonate solution, and sodium carbonate solution.

4. The anode slurry according to claim 2, characterized in that, The 6-bromo-2-isobutylone thioran was prepared according to the following method: A) Thian and 1-chloro-2-methylpropanol were mixed and subjected to a nucleophilic substitution reaction to give 2-isobutyranol; B) 2-Isobutanolthiaran was reacted in the presence of a catalyst to obtain 2-isobutanonethiaran; C) The 2-isobutyranone was reacted with pure bromine in the presence of a catalyst to give 6-bromo-2-isobutyranone.

5. The anode slurry according to claim 4, characterized in that, In step A), the molar ratio of the thioran and 1-chloro-2-methyl-propanol is 1:1 to 1:3; The nucleophilic substitution reaction is carried out in the presence of a weak base solution and an alcohol solution, wherein the weak base is selected from ammonia water, sodium bicarbonate solution and sodium carbonate solution, and the alcohol solution is selected from ethanol, propanol or butanediol. The nucleophilic substitution reaction is carried out at a temperature of 60-65°C for 28-34 hours.

6. The anode slurry according to claim 4, characterized in that, In step B), the catalyst is selected from chromium trioxide, and the reaction temperature is 21~25℃.

7. The anode slurry according to claim 4, characterized in that, In step C), the molar ratio of 2-isobutylonethioran to pure bromine is 1:2 to 1:3; The catalyst is selected from ferric tribromide; The substitution reaction was carried out at a temperature of 21-25°C for 18-20 hours.

8. The anode slurry according to claim 1, characterized in that, The solid raw materials in the anode slurry include: 95%~98% of the negative electrode active material; 0.06%~2% conductive agent; 1.3%~1.5% dispersant; 1%~3% adhesive; The amount of the suspending agent is 0.12% to 0.18% of the total amount of solid raw materials in the anode slurry.

9. A lithium-ion battery, characterized in that, Includes the anode slurry as described in any one of claims 1 to 8.

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