TWI603526B - Water-based negative electrode paste composition, negative electrode and lithium battery - Google Patents

Description

Water-based negative electrode slurry composition, negative electrode, and lithium ion battery

The present invention relates to a slurry composition, and more particularly to an aqueous negative electrode slurry composition, a negative electrode produced therefrom, and a lithium ion battery including the negative electrode.

In recent years, rechargeable lithium secondary batteries have become a highly anticipated battery system, which is widely used in portable electronic applications such as mobile phones, tablet computers, and digital cameras. Therefore, the requirements for secondary lithium batteries such as lightweight durability, high capacity, high voltage, high energy density, service life and high safety are becoming higher and higher.

In the conventional secondary lithium battery, graphite is usually used as the active material of the negative electrode. However, the theoretical capacity limit of graphite is 372 mAh/g, which is insufficient for the high-energy density and high capacity of the secondary lithium battery. Demanding higher and higher trends. In order to break through the limitation of capacitance, many researches on emerging negative active materials have been widely carried out, and bismuth-based materials have good development potential. However, during the charging and discharging process, the migration and migration of lithium ions may cause a violent volume expansion and contraction of the ruthenium-based material, resulting in the anode material being easily disintegrated and greatly reducing the cycle life of the battery. Therefore, the development of a novel negative electrode material capable of providing a lithium battery with high capacitance and high cycle life is one of the goals that those skilled in the art are currently aiming at.

In view of the above, the present invention provides an aqueous negative electrode slurry composition which can be used for a negative electrode of a lithium ion battery, whereby the lithium ion battery has high electric capacity and high cycle life, and it does not contain an organic solvent. Environmental protection concept.

The aqueous negative electrode slurry composition of the present invention includes an active material, an adhesive, a co-agent, and an aqueous solvent. The adhesive includes a copolymer, and the comonomer of the copolymer includes at least: an ethylenically unsaturated carboxylic acid monomer and an ethylenic terminal containing a phosphate monomer. The ethylenic terminal contains a phosphate monomer in an amount of from 2.5 mol% to 8 mol% based on the total number of moles of the ethylenically unsaturated carboxylic acid monomer and the ethylenic end-containing phosphate monomer.

In one embodiment of the present invention, the content of the carboxylic acid group in the ethylenically unsaturated carboxylic acid monomer is 35 wt% or more based on the total weight of the copolymer.

In one embodiment of the present invention, the total content of the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal-containing phosphate monomer is 95 wt% or more based on the total weight of the copolymer.

In one embodiment of the invention, the above ethylenically unsaturated carboxylic acid monomer comprises an acrylic monomer, a methacrylic monomer, a maleic acid monomer, an itaconic acid monomer, fumaric acid (fumaric) Acid) monomer, or crotonic acid monomer.

In an embodiment of the invention, the copolymer described above includes a structure represented by the following formula 1: Formula 1, wherein m is from 0.92 to 0.97, n is from 0.03 to 0.08, and R ₁ and R ₂ are each independently -H or C ₁ -C ₄ alkyl, and y is from 1 to 5.

In an embodiment of the invention, the copolymer has an average molecular weight of between 200,000 and 500,000.

In an embodiment of the invention, the active material includes a tantalum material and a carbon material, wherein the weight ratio of the tantalum material to the carbon material is between 0.21 and 0.31.

In one embodiment of the present invention, the content of the active material is 70 wt% to 85 wt%, and the content of the adhesive is 4 wt% to 10 based on the total weight of the solid content in the aqueous anode slurry composition. The wt%, the amount of the co-agent is from 5 wt% to 15 wt%.

In an embodiment of the invention, the aqueous anode slurry composition further includes a crosslinking agent including 9,9-bis[(2,3-epoxypropoxy)phenyl]anthracene, 2 2'-[(1-Methylethylene)bis(4,1-phenylenecarbaldehyde)diethylene oxide or tris(4-hydroxyphenyl)methanetriglycidyl ether.

In an embodiment of the present invention, the aqueous negative electrode slurry composition further includes an additive including a basic compound including lithium hydroxide, sodium hydroxide or potassium hydroxide.

The negative electrode of the present invention is produced from the aforementioned aqueous negative electrode slurry composition.

The lithium ion battery of the present invention includes the aforementioned negative electrode.

Based on the above, the aqueous negative electrode slurry composition of the present invention does not contain an organic solvent and conforms to the environmental protection concept, and the aqueous negative electrode slurry composition of the present invention can be obtained as a negative electrode suitable for a lithium ion battery, and is composed of a water-based negative electrode slurry. The invention comprises an active material, an adhesive, a co-solvent, and an aqueous solvent, wherein the adhesive comprises a comonomer comprising at least an ethylenically unsaturated carboxylic acid monomer and a copolymer of an ethylenic terminal having a phosphate monomer, and an alkene The carboxyl terminal contains a phosphate monomer having a specific molar ratio, thereby enabling the lithium ion battery to have a high capacity and a high cycle life.

The above described features and advantages of the present invention will be more apparent from the following description.

It should be noted that in the present specification, the range represented by "a value to another value" is a summary representation that avoids enumerating all the values in the range in the specification. Therefore, a particular numerical range is recited, and any numerical value in the numerical range and the numerical range defined by any numerical value in the numerical range are also disclosed, as in the specification. The smaller value range is the same.

Further, in the present text, the structure of the compound is sometimes represented by a skeleton formula. This representation can omit carbon atoms, hydrogen atoms, and carbon-hydrogen bonds. Of course, if the functional group is clearly drawn in the structural formula, the manufacturer will prevail.

In order to develop a negative electrode capable of high-capacity and high cycle life of a lithium ion battery and which does not require the use of an organic solvent in the preparation process, the present invention proposes an aqueous negative electrode slurry composition from the aqueous negative electrode slurry. The negative electrode prepared from the composition and the lithium ion battery including the negative electrode can achieve the above advantages. Hereinafter, the aqueous negative electrode slurry composition, the negative electrode, and the lithium ion battery of the present invention will be described in detail as a specific example of the present invention.

An embodiment of the present invention provides an aqueous negative electrode slurry composition comprising an active material, an adhesive, a co-agent, and an aqueous solvent. In detail, the aqueous negative electrode slurry composition of the present embodiment can be produced as a negative electrode suitable for a lithium ion battery. Hereinafter, the various components described above will be described in detail.

In the present embodiment, the active material is a material in which lithium ions can reversibly move in and out. In detail, the active material includes a ruthenium material including a ruthenium, a ruthenium oxide, a ruthenium nickel composite, a ruthenium carbon composite, or a ruthenium alloy, and the carbon material includes natural graphite, artificial graphite, and amorphous carbon. Or intermediate phase carbon microspheres. That is, in the present embodiment, the water-based negative electrode slurry composition uses both a tantalum material and a carbon material as active materials.

Further, in the present embodiment, the weight ratio of the ruthenium material to the carbon material is between 0.21 and 0.31. If the weight ratio of the bismuth material to the carbon material is less than 0.21, when the water-based negative electrode slurry composition is applied to the negative electrode of the lithium ion battery, the capacity increase is limited; if the weight ratio of the bismuth material to the carbon material is higher than 0.31, When the water-based negative electrode slurry composition is applied to a negative electrode of a lithium ion battery, the cell pole piece expansion ratio is excessively large and the cycle life is cracked.

In the present embodiment, the adhesive comprises a copolymer, and the comonomer of the copolymer includes at least: an ethylenically unsaturated carboxylic acid monomer and an ethylenic terminal containing a phosphate monomer. In detail, the ethylenically unsaturated carboxylic acid monomer includes, for example, an acrylic monomer, a methacrylic monomer, a maleic acid monomer, an itaconic acid monomer, a fumaric acid monomer, or A crotonic acid monomer, and an ethylenic terminal containing a phosphate monomer, for example, is represented by Formula I: Formula I, wherein R ₁ and R ₂ are each independently -H or C ₁ -C ₄ alkyl, and y is from 1 to 5.

In more detail, in one embodiment, the copolymer includes a structure represented by the following formula 1: Formula 1, wherein m is from 0.92 to 0.97, n is from 0.03 to 0.08, and R ₁ and R ₂ are each independently -H or C ₁ -C ₄ alkyl, and y is from 1 to 5. In this case, the ethylenically unsaturated carboxylic acid monomer is an acrylic monomer, and the ethylenic terminal contains a phosphate monomer, which is represented by the above formula I.

Further, in the present embodiment, the ethylenic terminal contains a phosphate monomer content of 2.5 mol% based on the total number of moles of the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal-containing phosphate monomer. Up to 8 mol%, preferably 3 mol% to 8 mol%. In detail, if the content of the phosphate-containing monomer at the ethylenic terminal is less than 2.5 mol%, the adhesive cannot effectively achieve the purpose of promoting the adhesion of the substrate; if the content of the ethylenic terminal contains a phosphate monomer higher than 8 In mol%, the proportion of the carboxylic acid in the adhesive is too low to be sufficient to achieve the effect of binding the active material and anti-swelling to crack the cycle life.

On the other hand, in the present embodiment, the content of the ethylenic terminal-containing phosphate monomer is 8 wt% based on the total weight of the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal-containing phosphate monomer. Up to 20 wt%, preferably 11 wt% to 18 wt%. In detail, if the content of the phosphate-containing terminal at the ethylenic terminal is less than 8 wt%, the adhesive cannot effectively achieve the purpose of enhancing the adhesion of the substrate; if the content of the ethylenic end-containing phosphate monomer is higher than 20 When wt%, the proportion of the carboxylic acid in the adhesive is too low, which is insufficient to achieve the effect of binding the active material and anti-swelling to crack the cycle life.

Further, in the present embodiment, the content of the carboxylic acid group in the ethylenically unsaturated carboxylic acid monomer is 35 wt% or more, preferably 37 wt% to 43 wt%, based on the total weight of the copolymer. In detail, if the content of the carboxylic acid group in the ethylenically unsaturated carboxylic acid monomer is less than 35 wt%, the proportion of the carboxylic acid in the adhesive is too low to achieve the effect of binding the active material and swelling resistance. Cracking the cycle life.

Further, in the present embodiment, the total content of the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal-containing phosphate monomer is 95 wt% or more, preferably 95 wt%, based on the total weight of the copolymer. To 97 wt%. In detail, if the total content of the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal-containing phosphate monomer is less than 95% by weight, the adhesion of the adhesive to the substrate will be insufficient, and the bound active material cannot be achieved. And the effect of anti-swelling causes the cycle life to crack. That is, in the present embodiment, the comonomer of the copolymer may optionally include an ethylenically unsaturated carboxylic acid monomer and a monomer other than the phosphate terminal at the ethylenic terminal. Specifically, in the present embodiment, the type of the other monomer is not particularly limited as long as it is different from the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal contains a phosphate monomer. For example, the other monomer can be represented by Formula II: Formula II.

Further, in the present embodiment, the average molecular weight of the copolymer is between 200,000 and 500,000. In detail, if the average molecular weight of the copolymer is less than 200,000, the adhesion of the adhesive to the substrate and the binding force to the active material will decrease; if the average molecular weight of the copolymer is higher than 500,000, the adhesive to the active material Dispersibility will decline. In addition, when the average molecular weight of the copolymer is within the above range, the copolymer not only has good dispersing power, but also has a good degree of coating for the active material, whereby the copolymer can be uniformly coated during the process of preparing the slurry. On the surface of the active substance.

In the present embodiment, a co-ducing agent is used to increase electrical contact between the active substances. In detail, in the present embodiment, the co-ducing agent includes graphitic carbon, carbon black, or a combination thereof.

In the present embodiment, the aqueous solvent includes water. That is, in the present embodiment, the active material, the adhesive, and the auxiliary agent included in the aqueous negative electrode slurry composition are soluble in water, thereby making it unnecessary to use the pair in the process of preparing the aqueous negative electrode slurry composition. Environmentally harmful organic solvents with environmentally friendly and environmentally friendly advantages. From another point of view, in the present embodiment, the adhesive is also prepared in an aqueous solvent environment, so that it is not necessary to use an environmentally harmful organic solvent in the preparation of the adhesive.

Further, in one embodiment, the active material is contained in an amount of 70 wt% to 85 wt%, preferably 71 wt% to 78 wt%, based on the total weight of the solid content in the aqueous anode slurry composition, and an adhesive The content is from 4 wt% to 10 wt%, preferably from 6 wt% to 10 wt%, and the content of the promoter is from 5 wt% to 15 wt%, preferably from 10 wt% to 15 wt%. Specifically, when the content of the active material is less than 70% by weight, when the aqueous negative electrode slurry composition is applied to the negative electrode of a lithium ion battery, the capacity is insufficient; if the content of the active material is higher than 85 wt%, the water system is When the negative electrode slurry composition is applied to a negative electrode of a lithium ion battery, the content of the additive for anti-swelling and electric conductivity enhancement is insufficient, and if the content of the adhesive is less than 4 wt%, the water-based negative electrode paste composition is applied to lithium ion. When the negative electrode of the battery is insufficient, the anti-swelling ability is insufficient; if the content of the adhesive is higher than 10 wt%, when the aqueous negative electrode slurry composition is applied to the negative electrode of the lithium ion battery, the conductivity of the negative electrode is lowered, and if the content of the auxiliary agent is When the water-based negative electrode slurry composition is applied to the negative electrode of the lithium ion battery, the conductivity of the negative electrode is insufficient; if the content of the promoter is higher than 15 wt%, the water-based negative electrode slurry composition is applied. In the negative electrode of a lithium ion battery, the Coulomb efficiency of the first ring decreases and the compaction density decreases.

It should be noted that in the present embodiment, the aqueous negative electrode slurry composition can be prepared as a negative electrode suitable for a lithium ion battery, and the water-permeable negative electrode slurry composition includes an active material, an adhesive, a promoter, and a water system. a solvent, wherein the adhesive comprises a copolymer, the comonomer of the copolymer comprising at least: an ethylenically unsaturated carboxylic acid monomer and an ethylenic terminal containing a phosphate monomer, and an ethylenically unsaturated carboxylic acid The total number of moles of the phosphate and the ethylenic end of the ethylenic terminal is from 2 to 8 mol% (ie, having a specific molar ratio), thereby including The lithium ion battery of the negative electrode prepared from the aqueous negative electrode slurry composition can have high electric capacity and high cycle life.

Further, in the case where the active material includes a bismuth material and a carbon material, the permeable aqueous anode slurry composition includes an active material, an adhesive, a co-agent, and an aqueous solvent, wherein the adhesive includes a comonomer including at least an olefin bond The unsaturated carboxylic acid monomer and the ethylenic terminal contain a copolymer of a phosphate monomer, and the ethylenic terminal contains a phosphate monomer having a specific molar ratio, so that the adhesive has good adhesion to the ruthenium material. Therefore, the adhesive can effectively coat the enamel material and produce a good binding force to the enamel material.

In addition, since the adhesive includes a comonomer comprising at least an ethylenically unsaturated carboxylic acid monomer and a copolymer having an ethylenic terminal containing a phosphate monomer, the adhesive is liable to be entangled by the intramolecular hydrogen bond. , thereby affecting the force of the adhesive on the enamel material, and reducing the binding force on the enamel material. In view of this, in order to enhance the binding force of the adhesive to the enamel material, the aqueous negative electrode slurry composition may further include an additive including a basic compound including lithium hydroxide, sodium hydroxide or hydroxide. Potassium, wherein the basic compound is preferably lithium hydroxide. Further, the content of the additive may be adjusted depending on the content of the adhesive, so the content of the additive is not particularly limited. In one embodiment, the content of the additive is from 1 wt% to 3 wt%, based on the total weight of the solid component in the aqueous anode slurry composition.

In addition, in order to enhance the binding force of the adhesive to the enamel material, the aqueous negative electrode slurry composition may further include a crosslinking agent including 9,9-bis[(2,3-epoxypropoxy). Phenyl]anthracene, 2,2'-[(1-methylethylidene)bis(4,1-phenylenecarbaldehyde)diethylene oxide, or tris(4-hydroxyphenyl)methane tricondensate Glyceryl ether. Specifically, the water-based negative electrode slurry composition is passed through a crosslinking step, and in the baking step performed when the negative electrode slurry composition is used to produce a negative electrode, the effect of improving the molecular weight of the adhesive by crosslinking can be achieved. Further, in one embodiment, the content of the crosslinking agent is from 1 wt% to 2 wt%, based on the total weight of the solid component in the aqueous negative electrode slurry composition.

Another embodiment of the present invention provides a negative electrode produced by the aqueous negative electrode slurry composition of any of the foregoing embodiments. In detail, in the present embodiment, the negative electrode is prepared, for example, in the following manner: First, the aqueous negative electrode slurry composition is applied onto a current collector. The method of applying the aqueous-based negative electrode slurry composition can be carried out by a coating method generally performed, for example, a dip coating method, a spin coating method, a spray coating method, a brush coating method, a roll transfer method, a screen printing method, or an inkjet method. Method or offset printing method. The current collector is, for example, a copper foil, a nickel foil or a gold foil, and its shape is not particularly limited, and it is preferable to use a sheet having a thickness of 0.001 mm to 0.5 mm. Next, the current collector coated with the aqueous negative electrode slurry composition is subjected to a baking step to remove the solvent. The method of the baking step is not particularly limited, and examples thereof include vacuum drying, air drying, warm air drying, infrared heating, far infrared heating, and the like, and the temperature condition of the baking step is, for example, 80 ^o C to 120 ^o C, and The time condition is, for example, 288 minutes to 384 minutes.

Further, before or after the baking step, selectively, a pressing treatment may be further included to increase the density of the active material in the negative electrode and to bring the negative electrode closer to the current collector. In detail, the method of the press treatment is not particularly limited, and examples thereof include a method of press pressing, roll pressing, or rolling pressing.

It should be noted that, in the present embodiment, the water-permeable negative electrode slurry composition includes an active material, an adhesive, a promoter, and an aqueous solvent, wherein the adhesive includes a copolymer, and the comonomer of the copolymer includes at least The ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal contain a phosphate monomer, and the ethylenic terminal contains a phosphate monomer having a specific molar ratio, thereby enabling the active material and the promoter in the negative electrode. It can be firmly adhered to the current collector through the adhesive.

Yet another embodiment of the present invention provides a lithium ion battery including the negative electrode of any of the foregoing embodiments. In detail, the structure of the lithium ion battery of the present embodiment is not particularly limited, that is, the lithium ion battery of the present embodiment can have an architecture of any one of lithium ion batteries known in the art.

It is to be noted that the lithium ion battery of the present embodiment has a high capacitance and a high cycle life by including the negative electrode in any of the above embodiments. In detail, as described above, the water-permeable negative electrode slurry composition includes an active material, an adhesive, a co-agent, and an aqueous solvent, wherein the adhesive includes a comonomer including at least an ethylenically unsaturated carboxylic acid monomer and The ethylenic terminal contains a copolymer of a phosphate monomer, and the ethylenic terminal contains a phosphate monomer having a specific molar ratio, so that the adhesive can have a good binding force to the tantalum material, thereby buffering the tantalum material in the charge. During the discharge process, the volume expansion and contraction of lithium ions occur due to the migration and migration of lithium ions, and the active material and the promoter in the negative electrode can be firmly adhered to the current collector through the adhesive to avoid the negative electrode. Self-collecting body desorption occurs after multiple charge and discharge processes. As a result, the negative electrode prepared from the aqueous negative electrode slurry composition is not easily disintegrated due to a drastic change in volume, so that the lithium ion battery of the present invention can have high electric capacity and high cycle life.

Features of the present invention will be more specifically described below with reference to Examples 1-3 and Comparative Examples 1-5. Although the following Examples 1-3 are described, the materials used, the amounts and ratios thereof, the processing details, the processing flow, and the like can be appropriately changed without departing from the scope of the invention. Therefore, the invention should not be construed restrictively by the examples described below. < Synthesis Example 1>

The adhesive represented by the formula a is prepared in the following synthetic steps: Formula a. However, the following synthetic steps are merely illustrative and not limiting the scope of the invention.

First, 600 g of deionized water and 0.87 g of initiator potassium persulfate were placed in a 1 L four-neck round bottom flask equipped with a stirrer, a condenser, a temperature control rod, and a dropping tube. Under a condition of a nitrogen, while stirring warmed to 60 ^o C, and dropwise addition of the aqueous monomer solution (98.6 g acrylic acid, 17.4 g 2-methyl-2-phosphate and 2-hydroxyethyl acrylate 72.5 g of deionized water), and the aqueous monomer solution was added dropwise within 4 hours. Subsequently, after holding the reaction temperature for 6 hours and warmed to 80 ^o C, and reacted for 2 hours to obtain an adhesive represented by the formula a. < Synthesis Example 2>

The adhesive represented by the formula b is prepared in the following synthetic steps: Formula b. However, the following synthetic steps are merely illustrative and not limiting the scope of the invention.

First, 620 g of deionized water and 0.55 g of initiator potassium persulfate were placed in a 1 L four-necked round bottom flask equipped with a stirrer, a condenser, a temperature control rod, and a dropping tube. Under a condition of a nitrogen, while stirring warmed to 62 ^o C, and dropwise addition of the aqueous monomer solution (87.6 g acrylic acid, 16.4 g of 2-methyl-2-hydroxyethyl methacrylate phosphate, 5.5 g of 2,2,2-trifluoroethylmethyl acrylate and 68.4 g of deionized water) and the aqueous monomer solution was added dropwise over 3.5 hours. Subsequently, after holding the reaction temperature for 6 hours and warmed to 80 ^o C, and reacted for 2 hours to obtain an adhesive represented by the formula b. < Synthesis Example 3>

The adhesive represented by the formula c is prepared in the following synthetic steps: Formula c. However, the following synthetic steps are merely illustrative and not limiting the scope of the invention.

First, 600 g of deionized water and 0.87 g of initiator potassium persulfate were placed in a 1 L four-neck round bottom flask equipped with a stirrer, a condenser, a temperature control rod, and a dropping tube. Under a condition of a nitrogen, while stirring warmed to 60 ^o C, and dropwise addition of the aqueous monomer solution (81.2 g acrylic acid, 34.8 g 2-methyl-2-phosphate and 2-hydroxyethyl acrylate 72.5 g of deionized water), and the aqueous monomer solution was added dropwise within 4 hours. Subsequently, after holding the reaction temperature for 6 hours and warmed to 80 ^o C, and reacted for 2 hours to obtain an adhesive represented by the formula c. < Synthesis Example 4>

The adhesive represented by the formula d is prepared in the following synthetic steps: Formula d. However, the following synthetic steps are merely illustrative and not limiting the scope of the invention.

First, 600 g of deionized water and 0.87 g of initiator potassium persulfate were placed in a 1 L four-neck round bottom flask equipped with a stirrer, a condenser, a temperature control rod, and a dropping tube. Under a condition of a nitrogen, while stirring warmed to 60 ^o C, and dropwise addition of the aqueous monomer solution (98.6 g acrylic acid, 17.4 g styrene and 72.5 g of deionized water), and a single over 4 hours The aqueous solution is added dropwise. Subsequently, after holding the reaction temperature for 6 hours and warmed to 80 ^o C, and reacted for 2 hours to obtain an adhesive represented by the formula d. < Example 1> Preparation of water-based negative electrode slurry composition

71.5 wt% of a mixture of ruthenium and graphite (wherein the weight ratio of ruthenium to graphite is 0.31) (the aforementioned active substance), 10 wt% of the adhesive represented by the formula a, and 15 wt% of Super P (by C65) sold by IMERYS (the aforementioned promoter), 1 wt% of epoxy bisphenol hydrazine (sold by Riyuexing Technology Co., Ltd.) (the aforementioned cross-linking agent), and 2.5 wt% of lithium hydroxide (The aforementioned additive) was kneaded by adding water (the above-mentioned aqueous solvent) to obtain a water-based negative electrode slurry composition of Example 1 having a solid content of 30%. Production of negative electrode

First, the water-based negative electrode slurry composition of the above-described Example 1 was coated on a copper foil (the aforementioned current collector) by a coater (manufactured by Shinkog Co., Ltd.). After drying, it was rolled through a roller compactor to obtain a copper foil having the water-based negative electrode paste composition of Example 1 having a thickness of about 70 μm, wherein the thickness of the copper foil was about 10 μm. Subsequently, to the cutter via the cutter blade 15 mm diam foil will be cut into the circular shape, placed in a vacuum oven for baking step at 110 ^o C 12 hours to give Example 1 negative electrode. Production of lithium ion battery

Using the negative electrode of the first embodiment, a half-cell was fabricated using a lithium sheet as a counter electrode, and the battery type was a CR 2032 coin cell to complete the fabrication of the lithium ion battery of Example 1.

The aqueous negative electrode slurry compositions of Examples 2-3 and Comparative Examples 1-5 were prepared according to a preparation procedure similar to that of Example 1, and the components and their types, and the ratios (% by weight) shown in Table 1. . Next, the negative electrode and the lithium ion battery of Example 2-3 and Comparative Example 1-5 were produced in the same manner as in Example 1, except that in Example 2-3 and Comparative Example 1-5, the negative electrode was used. The examples were prepared using the aqueous negative electrode slurry compositions of Examples 2-3 and Comparative Examples 1-5, and the lithium ion batteries including the negative electrodes of Examples 2-3 and Comparative Examples 1-5. Table 1         <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> Composition</td><td> Type</td><td> Example 1 </ Td><td> Example 2 </td><td> Example 3 </td><td> Comparative Example 1 </td><td> Comparative Example 2 </td><td> Comparative Example 3 </ Td><td> Comparative Example 4 </td><td> Comparative Example 5 </td></tr><tr><td> Active material</td><td> Mixture of cerium and graphite (where 矽The weight ratio to graphite is 0.31) </td><td> 71.5 wt% </td><td> -- </td><td> 71.5 wt% </td><td> -- </td> <td> 72.5 wt% </td><td> 72.5 wt% </td><td> 71.5 wt% </td><td> 71.5 wt% </td></tr><tr><td> a mixture of cerium and graphite (wherein the weight ratio of cerium to graphite is 0.21) </td><td> -- </td><td> 76.4 wt% </td><td> -- </td>< Td> 76.4 wt% </td><td> -- </td><td> -- </td><td> -- </td><td> </td></tr><tr> <td> Adhesive</td><td> Adhesive represented by Formula a</td><td> 10 wt% </td><td> 6 wt% </td><td> -- < /td><td> -- </td><td> -- </td><td> -- </td><td> -- </td><td> -- </td></ Tr><tr><td> Adhesive represented by formula b</td><td> -- </td><td> -- </td><td> 10 wt% </td><td > -- </td><t d> -- </td><td> -- </td><td> -- </td><td> -- </td></tr><tr><td> is represented by the formula c Adhesive</td><td> -- </td><td> -- </td><td> </td><td> -- </td><td> -- </td> <td> -- </td><td> 10 wt% </td><td> -- </td></tr><tr><td> Adhesive represented by formula d</td> <td> -- </td><td> -- </td><td> </td><td> -- </td><td> -- </td><td> -- </ Td><td> -- </td><td> 10 wt% </td></tr><tr><td> Polyacrylic acid (PAA) </td><td> -- </td>< Td> -- </td><td> </td><td> 6 wt% </td><td> -- </td><td> -- </td><td> -- </ Td><td> -- </td></tr><tr><td> Polyvinylidene fluoride (PVDF) </td><td> -- </td><td> -- </td ><td> </td><td> -- </td><td> 12.5 wt% </td><td> -- </td><td> -- </td><td> -- </td></tr><tr><td> Polyacrylonitrile (PAN) </td><td> -- </td><td> -- </td><td> </td>< Td> -- </td><td> -- </td><td> 12.5 wt% </td><td> -- </td><td> -- </td></tr>< Tr><td> 助助剂</td><td> Super P </td><td> 15 wt% </td><td> 15 wt% </td><td> 15 wt% </td ><td> 15 wt% </td><td> 15 wt% </td><td> 15 wt% </td><td> 15 wt% </td><td> 15 wt% </td ></tr><tr><td> Joint agent</td><td> epoxy bisphenol hydrazine</td><td> 1 wt% </td><td> 1 wt% </td><td> 1 wt% </td><td > 1 wt% </td><td> -- </td><td> -- </td><td> 1 wt% </td><td> 1 wt% </td></tr> <tr><td> Additives</td><td> Lithium hydroxide</td><td> 2.5 wt% </td><td> 1.6 wt% </td><td> 2.5 wt% </td ><td> 1.6 wt% </td><td> -- </td><td> -- </td><td> 2.5 wt% </td><td> 2.5 wt% </td>< /tr><tr><td> Solid content/solvent</td><td> 30%/water</td><td> 35%/water</td><td> 30%/water</td> <td> 35%/water</td><td> 45%/N-methyl-2-pyrrolidone (NMP) </td><td> 35%/water</td><td> 30%/water </td><td> 30%/water</td></tr></TBODY></TABLE>

After the lithium ion batteries of Examples 1-3 and 1-5 were prepared, the lithium ion batteries of Examples 1-3 and 1-5 were respectively subjected to a charge and discharge cycle test, and the measurement results thereof were recorded in In Table 2. < Charge discharge cycle test >

The lithium ion batteries of Examples 1-3 and Comparative Examples 1-5 were respectively charged and discharged under the following test conditions: the lithium migration electrode was a discharge test, and the lithium migration electrode was a charge test, and 0.1 C was performed at room temperature. The constant current is charged and discharged at a constant rate, and after each constant current discharge, a constant voltage discharge is performed to a current value of 0.01 C, and the test voltage ranges from 5 mV to 1500 mV. Further, the battery capacities of the lithium ion batteries of Examples 1-3 and Comparative Examples 1-5 in the completion of the fifth charge and discharge cycle are shown in Table 2. In addition, in order to more clearly compare the stability of the lithium ion battery, the discharge capacity of the ninth turn of the lithium ion battery of Examples 1-3 and 1-5 was adjusted for the discharge capacity of the fifth turn. Normally, the capacitance residual ratio of the lithium ion batteries of Examples 1-3 and 1-5 after the charge and discharge cycle of 20 cycles was calculated from the results, which are also shown in Table 2. Table 2         <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> </td><td> Charging capacity on the 5th lap (mAh/g) </ Td><td> Capacitance residual rate after 20 cycles of charge and discharge cycles (%) </td></tr><tr><td> Example 1 </td><td> 670 </td>< Td> 100 </td></tr><tr><td> Example 2 </td><td> 400 </td><td> 100 </td></tr><tr><td> Example 3 </td><td> 710 </td><td> 95 </td></tr><tr><td> Comparative Example 1 </td><td> 370 </td><td > 81 </td></tr><tr><td> Comparative Example 2 </td><td> 360 </td><td> <50 </td></tr><tr><td> Comparative Example 3 </td><td> 400 </td><td> <50 </td></tr><tr><td> Comparative Example 4 </td><td> 600 </td>< Td> 73 </td></tr><tr><td> Comparative Example 5 </td><td> 470 </td><td> 78 </td></tr></TBODY></ TABLE>

As is clear from Table 2, the lithium ion batteries of Examples 1 and 3 have higher electric capacity and high cycle life than the lithium ion batteries of Comparative Example 2-5. This result confirms that the water-based negative electrode slurry composition includes a comonomer including at least an ethylenically unsaturated carboxylic acid monomer and an ethylenic terminal containing a phosphate monomer and an ethylenic terminal having a phosphate monomer having a specific molar The proportion of the adhesive thereby enables the lithium ion battery including the negative electrode prepared from the aqueous negative electrode slurry composition to have high electric capacity and high cycle life.

Further, as is clear from Table 2, the lithium ion battery of Example 2 has higher capacity and high cycle life than the lithium ion battery of Comparative Example 1. This result confirmed that the use of the comonomer included at least the ethylenically unsaturated carboxylic acid monomer and the ethylenic group as compared with the lithium ion battery of Comparative Example 1 using the adhesive having only the ethylenically unsaturated carboxylic acid monomer. The lithium ion battery of Example 2 having an adhesive containing a phosphate monomer at the end has high capacity and cycle life.

Further, the surface condition of the negative electrode of the lithium ion battery of Example 1 and Comparative Example 4-5 after the third-lap charge-discharge cycle test was separately evaluated by a scanning electron microscope (SEM) to investigate Example 1. The change in volume expansion of the negative electrode of the lithium ion battery of Example 4-5 after a plurality of charge and discharge cycles was shown in Table 3. table 3         <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> </td><td> Expansion ratio of the negative electrode after 3 cycles of charge and discharge (% </td></tr><tr><td> Example 1 </td><td> 0 </td></tr><tr><td> Comparative Example 4 </td><td> 6 </td></tr><tr><td> Comparative Example 5 </td><td> 21 </td></tr></TBODY></TABLE>

As is clear from Table 3, the negative electrode of the lithium ion battery of Example 1 had an extremely low expansion ratio as compared with the lithium ion battery of Comparative Example 4-5. This result confirms that the water-based negative electrode slurry composition includes a comonomer including at least an ethylenically unsaturated carboxylic acid monomer and an ethylenic terminal containing a phosphate monomer and an ethylenic terminal having a phosphate monomer having a specific molar In the proportion of the adhesive, the negative electrode obtained from the composition of the aqueous negative electrode slurry is less likely to undergo a vigorous volume expansion due to the incorporation of lithium ions.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

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Claims (12)

An aqueous negative electrode slurry composition comprising: an active material; an adhesive, the adhesive comprising a copolymer, the comonomer of the copolymer comprising at least: an ethylenically unsaturated carboxylic acid monomer and an ethylenic terminal a phosphate monomer; a coagulant; and an aqueous solvent, wherein the ethylenic group is based on the total number of moles of the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal containing a phosphate monomer The terminal contains a phosphate monomer in an amount of from 2.5 mol% to 8 mol%. The aqueous negative electrode slurry composition according to claim 1, wherein the content of the carboxylic acid group in the ethylenically unsaturated carboxylic acid monomer is 35 wt% based on the total weight of the copolymer. the above. The aqueous negative electrode slurry composition according to claim 1, wherein the ethylenically unsaturated carboxylic acid monomer and the ethylenic terminal end contain a phosphate ester based on the total weight of the copolymer. The total content of the body is 95 wt% or more. The aqueous negative electrode slurry composition according to claim 1, wherein the ethylenically unsaturated carboxylic acid monomer comprises an acrylic monomer, a methacrylic monomer, a maleic acid monomer, and itaconic acid ( Itaconic acid) a monomer, a fumaric acid monomer, or a crotonic acid monomer. The aqueous negative electrode slurry composition according to claim 1, wherein the copolymer comprises a structure represented by the following formula 1: Formula 1, wherein m is from 0.92 to 0.97, n is from 0.03 to 0.08, and R ₁ and R ₂ are each independently -H or C ₁ -C ₄ alkyl, and y is from 1 to 5. The aqueous negative electrode slurry composition according to claim 1, wherein the copolymer has an average molecular weight of between 200,000 and 500,000. The aqueous negative electrode slurry composition according to claim 1, wherein the active material comprises a ruthenium material and a carbon material, wherein a weight ratio of the ruthenium material to the carbon material is between 0.21 and 0.31. The aqueous negative electrode slurry composition according to claim 1, wherein the active material is contained in an amount of 70 wt% to 85 wt% based on the total weight of the solid component in the aqueous negative electrode slurry composition. The adhesive is contained in an amount of 4 wt% to 10 wt%, and the auxiliary agent is contained in an amount of 5 wt% to 15 wt%. The aqueous negative electrode slurry composition according to claim 1, further comprising a crosslinking agent comprising 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene. 2,2'-[(1-methylethylidene)bis(4,1-phenylenecarbaldehyde)diethylene oxide or tris(4-hydroxyphenyl)methane triglycidyl ether. The aqueous negative electrode slurry composition according to claim 1, further comprising an additive comprising a basic compound comprising lithium hydroxide, sodium hydroxide or potassium hydroxide. A negative electrode obtained by the aqueous negative electrode slurry composition according to any one of claims 1 to 10. A lithium ion battery comprising the negative electrode according to claim 11 of the patent application.