A production process of high-capacity liquid-phase coating agent

Abstract

The invention discloses a production process of a liquid-phase coating agent, which belongs to the technical field of negative electrode production. The liquid-phase coating agent is produced by catalysis and compounding of multiple raw materials, and specifically comprises the following steps: cutting a 200-300 DEG C distillation range section of ethylene tar, adding an aldehyde catalyst to polymerize at 80-120 DEG C for 30-60 minutes, then heating to 230-250 DEG C, and keeping the temperature constant for 1-2 hours to obtain material 1; cutting a heavy component of catalytic oil slurry and compounding it with a component of ethylene tar above 400 DEG C, with a compounding mass ratio of (1-5):1, to obtain material 2; selecting light cracking tail oil, cutting a distillation range section above 300 DEG C, adding cycloalkyl thermal cracking oil to compound, with a compounding mass ratio of 1:(1-3), adding a carboxylic acid crosslinking agent after compounding, and crosslinking at 150-330 DEG C for 1-2 hours to make it a macromolecular crosslinking substance, to obtain material 3; and mixing the material 1, the material 2 and the material 3 according to a mass ratio of 5:2:4 to obtain the liquid-phase coating agent. The liquid coating agent produced by this process has the characteristics of less capacity loss, uniform coating and no loss of initial effect after coating.

Description

Technical Field

[0001] The invention relates to the technical field of liquid-phase coating agents for negative electrodes, and in particular to a production process of a high-capacity liquid-phase coating agent. Background Art

[0002] The negative electrode material is one of the key materials that determine the performance of lithium-ion batteries. With the research on fast-charging graphite, conventional graphite methods can no longer meet the demand for fast-charging performance; usually the material needs to be modified and modified. The methods for modifying graphite include doping with other elements, surface oxidation treatment, surface coating treatment, etc. Among them, surface coating treatment is the most mature technology. The principle is to use asphalt to coat graphite and carbonize it, so that an amorphous carbon coating layer is formed on the surface of the graphite, which reduces the specific surface area of ​​the negative electrode material, reduces the contact reaction between the surface active functional groups and the electrolyte, and increases the active sites at the same time, improving the cycle performance and charge rate performance of the negative electrode.

[0003] Coated asphalt generally has the characteristics of high softening point and high coking value. During use, it can effectively suppress the volume expansion of graphite and repair the surface defects of graphite, thereby improving performance. However, coated asphalt usually has a high softening point. In order to make the particle surface evenly coated during the solid phase coating process, more asphalt is usually used for coating, which will inevitably lead to problems such as reduced capacity and reduced first efficiency. Therefore, reducing the capacity loss caused by the use of coated asphalt and increasing the uniformity of the infiltration of the coated asphalt have become top priorities.

[0004] Based on this, liquid phase coating agents came into being; liquid phase coating improves the uniformity of graphite surface coating. At the same time, due to the low residual carbon and viscosity, the coating layer remaining on the graphite surface after carbonization is thinner, thus avoiding capacity loss. Summary of the invention

[0005] The object of the present invention is to provide a production process of a high-capacity liquid-phase coating agent to solve one or more of the above-mentioned prior art problems.

[0006] The present invention provides a production process of a high-capacity liquid-phase coating agent, comprising the following steps:

[0007] Cut off the 200-300°C distillation range of ethylene tar, add aldehyde catalyst and polymerize at 80-120°C for 30-60 minutes, then raise the temperature to 230-250°C and keep the temperature constant for 1-2 hours to obtain material 1;

[0008] The heavy component of the catalytic oil slurry is cut and compounded with the component of ethylene tar above 400°C, and the compounding mass ratio is (1-5):1 to obtain material 2;

[0009] Select light cracking tail oil, cut the distillation section above 300°C, add cycloalkyl thermal cracking oil to compound, the compounding mass ratio is 1:(1-3), add carboxylic acid crosslinking agent after compounding, crosslink for 1-2h at 150-330°C to make it into a macromolecular crosslinking substance, and obtain material 3;

[0010] The material 1, the material 2 and the material 3 are mixed in a mass ratio of 5:2:4 to obtain the liquid coating agent.

[0011] In some embodiments, the aldehyde catalyst is selected from one of ethylenediaminetetraacetic acid, triethanolamine or trioxymethylene.

[0012] In some embodiments, the aldehyde catalyst is trioxymethylene.

[0013] In some embodiments, the aldehyde catalyst is added in an amount of 0.5% to 5% by weight.

[0014] In some embodiments, the heating rate is 3°C / min.

[0015] In some embodiments, the carboxylic acid crosslinking agent is selected from one of terephthalic acid, biphenyl acid or anthranilic acid.

[0016] In some embodiments, the carboxylic acid cross-linking agent is terephthalic acid.

[0017] Beneficial effects of the present invention:

[0018] 1. Cutting the low molecular weight distillation section of ethylene tar and polymerizing it at low temperature under a catalyst can effectively increase the content of β resin in ethylene tar and increase the adhesion of tar. Moreover, since it is a low molecular weight substance and the polymerization temperature is low, the viscosity of the solution after polymerization is small, which is beneficial to the wettability of the material: increasing the content of β resin in ethylene tar and increasing the adhesion of tar. Moreover, since it is a low molecular weight substance and the polymerization temperature is low, the viscosity of the solution after polymerization is small, which is beneficial to the wettability of the material.

[0019] 2. The addition of heavy components of catalytic oil slurry is beneficial to the formation of large-layer aromatic structure, and is beneficial to the orderly formation and development of lamellar structure after carbonization of liquid phase coating agent, which plays a positive role in the performance of capacity. The introduction of heavy components of ethylene tar is beneficial to the residual carbon of large molecular components, making the residual coating layer after carbonization more complete.

[0020] 3. The cracking tail oil and cycloalkyl thermal cracking oil are mainly saturated molecules, and the molecular configuration is mainly spatial molecules, and the crystal surface structure is relatively three-dimensional. Under the action of the cross-linking agent, the cross-linked molecular morphology is more three-dimensional, and after carbonization, it is beneficial to provide active sites, increase the ion transmission speed, and increase the rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the SEM image of the uncoated graphite negative electrode;

[0022] Figure 2 This is the SEM image of the liquid-coated graphite negative electrode. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the performance of the present invention, and are not limited to the following examples.

[0024] Embodiment 1:

[0025] Step 1: Cut the 200-300°C distillation range of ethylene tar, add aldehyde catalyst trioxymethylene and polymerize at 120°C for 30 minutes; the amount of trioxymethylene added is 5% by weight, and after 30 minutes, the temperature is increased to 250°C at 3°C / min and kept at this temperature for 1 hour, which is recorded as material 1;

[0026] Step 2: Cut the heavy component of the catalytic oil slurry and compound it with the component of ethylene tar above 400°C, with a compounding ratio of 5:1, recorded as material 2;

[0027] Step 3: Select light cracking tail oil, cut the distillation section above 300°C, add cycloalkyl thermal cracking oil to compound, and the compounding ratio is 1:1. After compounding, add carboxylic acid crosslinking agent terephthalic acid, crosslink at 300°C for 1.5 hours to make it a macromolecular crosslinked substance, recorded as material 3;

[0028] Step 4: Material 1, material 2, and material 3 are mixed in a weight ratio of 5:2:4 to obtain a liquid coating agent.

[0029] The uncoated graphite negative electrode (such as Figure 1 ) and the liquid-coated graphite negative electrode prepared in Example 1 (as shown Figure 2 The specific detection method is shown in the following table:

[0030]

[0031] The test results are shown in the following table:

[0032]

[0033] The liquid phase coating agent produced by the production process in the embodiment of the present invention has a residual carbon of 15% and a capacity of 347.5 mAh / g, which is higher than the 340 mAh / g of the coated asphalt, and the capacity loss after coating is 0.2 mAh / g, and the first efficiency is reduced by 2 mAh / g without loss, which is higher than the capacity of the coated asphalt coating, and the first efficiency is reduced by 2%-3%.

[0034] The above description is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the creative concept of the present invention, and these should also be regarded as within the scope of protection of the present invention.

Claims

1. A production process of a high-capacity liquid phase coating agent, characterized in that: The following steps are involved: Cut off the 200-300°C distillation range of ethylene tar, add aldehyde catalyst and polymerize at 80-120°C for 30-60 minutes, then raise the temperature to 230-250°C and keep the temperature constant for 1-2 hours to obtain material 1; The heavy component of the catalytic oil slurry is cut and compounded with the component of ethylene tar above 400°C, and the compounding mass ratio is (1-5):1 to obtain material 2; Select light cracking tail oil, cut the distillation section above 300°C, add cycloalkyl thermal cracking oil to compound, the compounding mass ratio is 1:(1-3), add carboxylic acid crosslinking agent after compounding, crosslink for 1-2h at 150-330°C to make it into a macromolecular crosslinking substance, and obtain material 3; The material 1, the material 2 and the material 3 are mixed in a mass ratio of 5:2:4 to obtain the liquid coating agent.

2. The production process according to claim 1, characterized in that: The aldehyde catalyst is selected from one of ethylenediaminetetraacetic acid, triethanolamine or trioxymethylene.

3. The production process according to claim 2, characterized in that: The aldehyde catalyst is trioxymethylene.

4. The production process according to claim 1, characterized in that: The added amount of the aldehyde catalyst is 0.5%-5% by weight.

5. The production process according to claim 1, characterized in that: The heating rate is 3°C / min.

6. The production process according to claim 1, characterized in that: The carboxylic acid crosslinking agent is selected from terephthalic acid, biphenyl acid or anthranilic acid.

7. The production process according to claim 6, characterized in that: The carboxylic acid crosslinking agent is terephthalic acid.

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