Electrode composition for lithium ion batteries, electrode for lithium ion batteries, and lithium ion batteries

Abstract

To provide an electrode composition for lithium-ion battery capable of manufacturing an electrode having a high permeation property of electrolytic solution and an excellent charge and discharge efficiency (coulomb efficiency).SOLUTION: An electrode composition for lithium-ion battery contains a compound (A) that is an alkylene oxide addition product of alkyl alcohol. An HLB value of the compound (A) is 11.5 to 18.0.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrode composition for a lithium ion battery, an electrode for a lithium ion battery, and a lithium ion battery. [Background technology]

[0002] Due to their high voltage and high energy density, lithium-ion batteries are widely used in the field of portable information devices, and have established themselves as the standard battery for mobile devices such as mobile phones and laptop computers. While their applications continue to expand, their application in hybrid and electric vehicles, in addition to their traditional applications, has also been considered, and some have already been put into practical use. To further popularize these applications, lithium-ion batteries are required to have higher capacity and power output, and various technologies are being attempted to apply them.

[0003] One way to improve the capacity of secondary batteries is to increase electrode density. By densely packing the active material, more capacity can be obtained. However, increasing the electrode density makes it difficult for the electrolyte to penetrate the electrode, resulting in problems such as less capacity than the theoretical value and a deterioration in output characteristics.

[0004] To solve these problems, Patent Document 1 discloses a technique for improving electrolyte permeability by providing grooves on the electrode surface. Patent Document 2 discloses a technique for improving electrolyte permeability by adjusting the particle size and shape of the active material. Furthermore, Patent Document 3 discloses a technique for improving electrolyte permeability by adjusting the electrode density. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-27633 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-151088 [Patent Document 3] Japanese Patent Publication No. 2020-053282 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method of Patent Document 1 involves a step of pressing the electrode surface with a roller having irregularities to form grooves on the surface, which necessitates the introduction of new equipment, which is a problem. Furthermore, although the methods of Patent Documents 2 and 3 show some improvement in permeability, the effect is not sufficient.

[0007] The present invention solves the above-mentioned problems and aims to provide an electrode composition for lithium ion batteries that can produce electrodes that have high electrolyte permeability and excellent charge / discharge efficiency (Coulomb efficiency). [Means for solving the problem]

[0008] The present inventors have made extensive studies and arrived at the present invention. The present invention relates to an electrode composition for lithium ion batteries containing compound (A), which is an alkylene oxide adduct of alkyl alcohol, wherein the HLB value of compound (A) is 11.5 to 18.0; an electrode for lithium ion batteries obtained by compression molding the electrode composition for lithium ion batteries; and a lithium ion battery comprising the electrode for lithium ion batteries. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an electrode composition for a lithium ion battery that allows the production of an electrode having high electrolyte permeability and excellent charge / discharge efficiency (Coulomb efficiency). DETAILED DESCRIPTION OF THE INVENTION

[0010] [Electrode composition for lithium ion batteries] The electrode composition for lithium ion batteries of the present invention is an electrode composition for lithium ion batteries containing compound (A), which is an alkylene oxide adduct of alkyl alcohol, wherein the HLB value of compound (A) is 11.5 to 18.0.

[0011] The compound (A) is an alkylene oxide adduct of an alkyl alcohol having an HLB value of 11.5 to 18.0. The HLB value of the compound (A) is preferably 12.0 to 18.0, more preferably 13.0 to 15.0, and may be 13.4 to 17.8, or 13.4 to 16.0.

[0012] HLB is a measure of the balance between hydrophilicity and lipophilicity, with a higher HLB indicating a higher inorganic nature. It is known as a value calculated by the Oda method, as described in, for example, "Introduction to Surfactants," 2007, Sanyo Chemical Industries, Ltd., by Takehiko Fujimoto, p. 212, and is not a value calculated by the Griffin method. The HLB value can be calculated from the ratio of the organicity value to the inorganicity value of an organic compound. HLB=10×Inorganic / Organic Here, the inorganic and organic values ​​in the above formula represent index values ​​that express organic and inorganic properties proposed by Fujita et al., and can be calculated using the values ​​in the table on page 213 of the aforementioned "Introduction to Surfactants."

[0013] In the electrode composition for a lithium ion battery of the present invention, it is preferable that the average number of moles of the alkylene oxide added is 6 to 40, the alkylene oxide contains ethylene oxide, and the molar ratio of ethylene oxide in the alkylene oxide is 85% or more based on the total number of moles of the alkylene oxide.

[0014] Compound (A) is an alkylene oxide adduct of an alkyl alcohol. The alkylene oxide preferably contains ethylene oxide. Alternatively, the alkylene oxide may contain alkylene oxides other than ethylene oxide. Examples of alkylene oxides other than ethylene oxide include propylene oxide and butylene oxide. In the present specification, alkylene oxide may be abbreviated as AO, ethylene oxide as EO, propylene oxide as PO, and butylene oxide as BO.

[0015] The alkylene oxide may be a combination of ethylene oxide and propylene oxide, a combination of ethylene oxide and butylene oxide, or a combination of ethylene oxide, propylene oxide and butylene oxide. When the alkylene oxide is composed of a plurality of types of alkylene oxides, the addition may be random addition or block addition.

[0016] The molar ratio of ethylene oxide in the alkylene oxide is preferably 85% or more based on the total number of moles of alkylene oxide. The alkylene oxide may be ethylene oxide alone, that is, the molar ratio of ethylene oxide in the alkylene oxide may be 100% based on the total number of moles of alkylene oxide. The molar ratio of ethylene oxide in the alkylene oxide may be 85 to 100%, 87 to 100%, 92 to 100%, 85 to 87%, 85 to 92%, or 87 to 92%.

[0017] In the electrode composition for lithium ion batteries of the present invention, the average number of moles of alkylene oxide added is preferably 6 to 40. The average number of moles of alkylene oxide added may be 9-40, 10-30, 10-20, or 20-40. When there are multiple types of alkylene oxides, the number of moles of alkylene oxide added is the total number of moles of the multiple types of alkylene oxides added.

[0018] When the molar ratio of ethylene oxide in the alkylene oxide in compound (A) is 85% or more based on the total number of moles of alkylene oxide, and the average number of moles of alkylene oxide added is 6 to 40, it is possible to obtain an electrode composition for lithium ion batteries that has higher electrolyte permeability and can produce an electrode with better charge / discharge efficiency.

[0019] The alkyl group of the alkyl alcohol constituting the alkylene oxide adduct of alkyl alcohol preferably has 8 to 17 carbon atoms, and more preferably 8 to 15 carbon atoms. The alkyl group of the alkyl alcohol having 8 to 17 carbon atoms may be either a straight chain or a branched chain. Examples of alkyl alcohols having 8 to 17 carbon atoms include octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, cetyl alcohol, 2-ethylhexanol, isodecanol, and isotridecanol.

[0020] A specific example of compound (A) is an alkylene oxide adduct of 2-ethylhexanol. In this case, the alkylene oxide preferably contains ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide is 85% or more, preferably 92% or more. The average number of moles of alkylene oxide added is preferably 6 to 40, more preferably 9 to 40, more preferably 6 to 20, and even more preferably 9 to 20.

[0021] Another specific example of compound (A) is an alkylene oxide adduct of isodecanol. In this case, the alkylene oxide preferably contains ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide is preferably 85% or more, more preferably 87% or more. It is also preferable that the alkylene oxide is ethylene oxide alone. The average number of moles of alkylene oxide added is preferably 6-40, more preferably 9-40, even more preferably 6-20, and even more preferably 9-20.

[0022] Other specific examples of compound (A) include alkylene oxide adducts of pentadecanol. In this case, the alkylene oxide is preferably ethylene oxide alone. The average number of moles of alkylene oxide added is preferably 6 to 40, more preferably 9 to 40, even more preferably 6 to 20, and even more preferably 9 to 20.

[0023] Another specific example of compound (A) is an alkylene oxide adduct of cetyl alcohol. In this case, the alkylene oxide preferably contains ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide is preferably 80% or more. It is also preferable that the alkylene oxide is ethylene oxide alone. The average number of moles of alkylene oxide added is preferably 6-40, more preferably 9-40, even more preferably 6-20, and even more preferably 9-20.

[0024] Another specific example of compound (A) is an alkylene oxide adduct of dodecanol. In this case, the alkylene oxide preferably contains ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide is preferably 80% or more. It is also preferable that the alkylene oxide is ethylene oxide alone. The average number of moles of alkylene oxide added is preferably 6-40, more preferably 9-40, even more preferably 6-20, and even more preferably 9-20.

[0025] Another specific example of compound (A) is an alkylene oxide adduct of hexanol. In this case, the alkylene oxide is preferably ethylene oxide alone. The average number of moles of alkylene oxide added is preferably 6 to 40, more preferably 9 to 40, even more preferably 6 to 20, and even more preferably 9 to 20.

[0026] Another specific example of compound (A) is an alkylene oxide adduct of octadecanol. In this case, the alkylene oxide is preferably ethylene oxide alone. The average number of moles of alkylene oxide added is preferably 6 to 40, more preferably 9 to 40, even more preferably 6 to 20, and even more preferably 9 to 20.

[0027] Another specific example of compound (A) is an alkylene oxide adduct of decanol. In this case, the alkylene oxide is preferably ethylene oxide alone. The average number of moles of alkylene oxide added is preferably 6 to 40, more preferably 9 to 40, even more preferably 6 to 20, and even more preferably 9 to 20.

[0028] Compound (A) may be a combination of two or more alkylene oxide adducts of alkyl alcohol. For example, a mixture of an alkylene oxide adduct of 2-ethylhexanol and an alkylene oxide adduct of isodecanol can be mentioned. Further, a mixture of multiple types of alkylene oxide adducts of pentadecanol, each having a different average number of moles of alkylene oxide added, may also be used. Multiple types of alkylene oxide adducts of alkyl alcohols may be combined to adjust the HLB of the mixture to 11.5 to 18.0. The HLB of the mixture can be calculated as the sum (molar average value) of the HLB values ​​obtained by multiplying the HLB of each compound by its molar ratio.

[0029] Furthermore, the lithium ion battery electrode composition may contain an alkylene oxide adduct of an alkyl alcohol having an HLB value other than 11.5 to 18.0, in addition to an alkylene oxide adduct of an alkyl alcohol having an HLB value of 11.5 to 18.0.

[0030] In the electrode composition for lithium ion batteries, known materials constituting electrode compositions for lithium ion batteries can be used as ingredients other than compound (A). The electrode composition for lithium ion batteries contains at least an electrode active material. The electrode active material may be a positive electrode active material or a negative electrode active material.

[0031] The positive electrode active material may be a composite oxide of lithium and a transition metal {composite oxides containing one type of transition metal (e.g., LiCoO2, LiNiO2, LiAlMnO4, LiMnO2, and LiMn2O4), composite oxides containing two types of transition metal elements (e.g., LiFeMnO4, LiNi 1-x Co x O2, LiMn 1-y Co y O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3 O2 and LiNi 0.8 Co 0.15 Al 0.05 O2) and composite oxides containing three or more transition metal elements [e.g., LiM a M' b M'' c O2 (M, M' and M'' are different transition metal elements, and a + b + c = 1 is satisfied. For example, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3O2), etc.}, lithium-containing transition metal phosphates (for example, LiFePO4, LiCoPO4, LiMnPO4, and LiNiPO4), transition metal oxides (for example, MnO2 and V2O5), transition metal sulfides (for example, MoS2 and TiS2), and conductive polymers (for example, polyaniline, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene, and polyvinylcarbazole), and two or more of them may be used in combination. The lithium-containing transition metal phosphate may have some of the transition metal sites substituted with other transition metals.

[0032] Examples of the negative electrode active material include carbon-based materials [graphite, non-graphitizable carbon (hard carbon), amorphous carbon, burned resins (e.g., phenolic resins, furan resins, etc., which are burned and carbonized), cokes (e.g., pitch coke, needle coke, petroleum coke, etc.), and carbon fibers], silicon-based materials [silicon, silicon oxide (SiO x ), silicon-carbon composites (carbon particles whose surfaces are coated with silicon and / or silicon carbide, silicon particles or silicon oxide particles whose surfaces are coated with carbon and / or silicon carbide, and silicon carbide, etc.) and silicon alloys (silicon-aluminum alloys, silicon-lithium alloys, silicon-nickel alloys, silicon-iron alloys, silicon-titanium alloys, silicon-manganese alloys, silicon-copper alloys, silicon-tin alloys, etc.), conductive polymers (e.g., polyacetylene and polypyrrole), metals (tin, aluminum, zirconium, titanium, etc.), metal oxides (titanium oxide and lithium-titanium oxide, etc.) and metal alloys (e.g., lithium-tin alloys, lithium-aluminum alloys, lithium-aluminum-manganese alloys, etc.), and mixtures of these with carbon-based materials. When the electrode active material is a negative electrode active material, graphite or hard carbon is preferable as the negative electrode active material.

[0033] The lithium ion battery electrode composition may contain a conductive additive, a binder resin, and a thickener, or may not contain any of these components. Examples of conductive additives include metals [aluminum, stainless steel (SUS), silver, gold, copper, titanium, etc.], carbon [graphite (flaky graphite (UP)), carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, etc.) and carbon nanofibers (CNF), etc.], and mixtures thereof. The conductive aid is preferably acetylene black.

[0034] Examples of binder resins include starch, polyvinylidene fluoride, polyvinyl alcohol, polyvinylpyrrolidone, tetrafluoroethylene, styrene-butadiene rubber (SBR), polyethylene, and polypropylene. Examples of thickeners include carboxymethyl cellulose (CMC).

[0035] The content of compound (A) in the electrode composition for lithium ion batteries is preferably 0.001 to 2% by weight based on the weight of the electrode composition for lithium ion batteries. When the content of compound (A) is within this range, the effects of including compound (A) can be more suitably exhibited.

[0036] [Electrodes for lithium-ion batteries] The lithium ion battery electrode of the present invention is obtained by compression molding the lithium ion battery electrode composition of the present invention. The method for compression molding the lithium ion battery electrode composition is not particularly limited, and methods such as roll pressing, pressing with a press, etc. can be used. The electrode density of the lithium ion battery electrode obtained by compression molding the lithium ion battery electrode composition is preferably 1.0 to 2.0 g / ml. The electrode density defined here means the density in a state where the electrolyte has not been permeated into the electrode composition for a lithium ion battery. A lithium ion battery electrode obtained using the lithium ion battery electrode composition of the present invention has high electrode density and yet is excellent in electrolyte permeability.

[0037] [Lithium-ion battery] The lithium ion battery of the present invention comprises the lithium ion battery electrode of the present invention. In the lithium ion battery of the present invention, the electrolyte solution is sufficiently permeated into the lithium ion battery electrode of the present invention.

[0038] The lithium ion battery of the present invention is equipped with the lithium ion battery electrode of the present invention, and has excellent charge / discharge efficiency (coulomb efficiency) because the electrolyte solution is sufficiently permeated into the electrode.

[0039] Known materials can be used for the components of the lithium ion battery of the present invention other than the electrodes for the lithium ion battery. That is, known materials can be used as the materials for the current collector, the electrolyte, the separator, and the like. As the electrolytic solution, it is preferable to use ethylene carbonate, diethyl carbonate, propylene carbonate, etc. as a non-aqueous solvent. It is preferable to use LiPF6 (lithium hexafluorophosphate), LiFSI (lithium bis(fluorosulfonyl)imide), etc. as an electrolyte.

[0040] In the lithium ion battery of the present invention, only the positive electrode may be composed of the lithium ion battery electrode of the present invention, only the negative electrode may be composed of the lithium ion battery electrode of the present invention, or both the positive electrode and the negative electrode may be composed of the lithium ion battery electrode of the present invention.

[0041] The lithium ion battery of the present invention can be used as a lithium ion battery for use in mobile phones, personal computers, hybrid vehicles, electric vehicles, stationary power sources, etc.

[0042] [Method of manufacturing an electrode composition for lithium ion batteries] The electrode composition for a lithium ion battery of the present invention can be obtained by mixing compound (A) with other components (electrode active material and, if necessary, components such as a conductive aid, a binder resin and a thickener). Compound (A) can also be obtained by carrying out an addition reaction of alkylene oxide to alkyl alcohol by a known method.

[0043] The present specification discloses the following:

[0044] The present disclosure (1) is an electrode composition for a lithium ion battery containing a compound (A) that is an alkylene oxide adduct of an alkyl alcohol, wherein the HLB value of the compound (A) is 11.5 to 18.0.

[0045] The present disclosure (2) is the electrode composition for a lithium ion battery according to the present disclosure (1), in which the average number of moles of the alkylene oxide added is 6 to 40, the alkylene oxide contains ethylene oxide, and the molar ratio of ethylene oxide in the alkylene oxide is 85% or more based on the total number of moles of the alkylene oxide.

[0046] The present disclosure (3) is the electrode composition for lithium ion batteries according to the present disclosure (1) or (2), in which the content of the compound (A) is 0.001 to 2% by weight based on the weight of the electrode composition for lithium ion batteries.

[0047] The present disclosure (4) is the electrode composition for a lithium ion battery according to any one of the present disclosures (1) to (3), wherein the alkyl group of the alkyl alcohol has 8 to 17 carbon atoms.

[0048] The present disclosure (5) is a lithium ion battery electrode obtained by compression molding the lithium ion battery electrode composition according to any one of the present disclosures (1) to (4).

[0049] The present disclosure (6) is a lithium ion battery including the lithium ion battery electrode according to the present disclosure (5). [Example]

[0050] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples as long as they do not deviate from the gist of the present invention. Unless otherwise specified, parts mean parts by weight and % means % by weight.

[0051] (Production Example 1: Production of Additive 1) Additive 1, an alkylene oxide adduct of alkyl alcohol, was produced by adding ethylene oxide (EO) and propylene oxide (PO) to 2-ethylhexanol. In Table 1, the AO structure is shown as EO / PO. The average number of moles of AO added was 9.5, the sum of EO and PO, and the molar ratio of EO was 92%. The HLB was 14.3.

[0052] (Production Example 2-8: Production of Additive 2-8) Additives 2-8 were produced in the same manner as in Production Example 1, except that the type of alkyl alcohol, the AO composition, the average number of moles of AO added, and the EO ratio were changed as shown in Table 1.

[0053] (Production Example 9: Preparation of Additive 9) Polyethylene glycol (PEG) with an average EO addition mole number of 45 was prepared as additive 9.

[0054] (Production Example 10-13: Production of Additive 10-13) In Production Examples 10 and 11, Additives 10 and 11 were produced by mixing Additives 1 and 6 in the weight ratios shown in Table 2. In Production Examples 12 and 13, Additives 2 and 7 were mixed in the weight ratio shown in Table 2 to produce Additives 12 and 13.

[0055] [Table 1]

[0056] [Table 2]

[0057] (Production Example 14-22: Production of Additive 14-22) Additives 14-22 were produced in the same manner as in Production Example 1, except that the type of alkyl alcohol, the AO composition, the average number of moles of AO added, and the EO ratio were changed as shown in Table 3.

[0058] [Table 3]

[0059] (Examples 1-16, 17-31, Comparative Examples 1-3, 4-8: Preparation of electrodes) A mixture was obtained by weighing and mixing the electrode active material, conductive additive, and thickener according to the weight parts shown in Table 4 or Table 5. 3 g of water and additives were added to the mixture, and the mixture was stirred at 2000 rpm for 1 minute using a planetary stirring mixer / kneader (Awatori Rentaro [manufactured by Thinky Corporation]). 2 g of water was then added, and the mixture was stirred at 2000 rpm for 1 minute using the Awatori Rentaro. Furthermore, the binder resin was added in the amount shown in Table 4 or Table 5, and the mixture was stirred at 2000 rpm for 1 minute using the Awatori Rentaro to prepare a slurry for the negative electrode active material layer. The obtained slurry was applied to one side of a current collector (copper foil) using a wire bar in the atmosphere, pre-dried overnight in a draft, and then punched out to a diameter of 16 mm, further dried at 100°C under reduced pressure (1.3 kPa) for 30 minutes, and pressed in a press to the target electrode density (electrode thickness) to produce a negative electrode for evaluating electrolyte permeability. The drying conditions were changed to drying at 100° C. for 2 hours or more to prepare a negative electrode for evaluating coulomb efficiency. Graphite or HC (hard carbon) was used as the electrode active material. As the conductive additive, AB (acetylene black: Denka Black Li100, manufactured by Denka Co., Ltd.) was used. CMC (carboxymethyl cellulose) was used as a thickener. SBR (styrene butadiene rubber) was used as the binder resin.

[0060] <Evaluation of electrolyte permeability (electrolyte permeation time)> 50 μL of electrolyte was dropped onto the prepared negative electrode for evaluating electrolyte permeability, and the time (minutes) until the electrolyte permeated into the electrode was measured. A shorter permeation time indicates better permeability. When the electrolyte solution was dropped onto the negative electrode for evaluating electrolyte permeability, the color of the area where the electrolyte solution was dropped became darker. As the electrolyte solution soaked into the electrode, the color returned to normal, so the time until the color of the negative electrode for evaluating electrolyte permeability returned to normal was measured. The measurement results are shown in Tables 4 and 5. As the electrolyte, electrolyte 1 (EC / DEC=1 / 1 (volume ratio), LiPF61M) or electrolyte 2 (EC / PC=1 / 1 (volume ratio), LiFSI 1.73M) was used, and permeability was evaluated. EC stands for ethylene carbonate, DEC for diethyl carbonate, and PC for propylene carbonate. LiPF6 stands for lithium hexafluorophosphate, and LiFSI stands for lithium bis(fluorosulfonyl)imide.

[0061] <Production of batteries for charge / discharge tests> (Preparation of positive electrode) NCA (LiNi 0.8 Co 0.15 Al 0.05 A mixture (solids concentration 10 wt%) was prepared by mixing 90 parts by weight of 02 powder, 5.0 parts by weight of AB as a conductive additive, and 5.0 parts by weight of polyvinylidene fluoride as a binder with N-methylpyrrolidone (NMP). The mixture was stirred at 2000 rpm for 1 minute using a planetary stirring mixer (Thinky Mixer, manufactured by THINKY CORPORATION) to prepare a slurry for the positive electrode active material layer. The obtained slurry was applied to one side of a current collector {carbon-coated aluminum foil [product name "Carbon-Coated Aluminum Foil"], manufactured by Toyo Aluminum Co., Ltd.} using a wire bar in the atmosphere, pre-dried overnight in a draft, and then punched out to a size of 16 mm diameter, dried at 100°C for 2 hours, and pressed in a press to prepare a positive electrode for evaluating coulombic efficiency.

[0062] A positive electrode for evaluating coulombic efficiency, a separator [product name "#3501" manufactured by Celgard], and a negative electrode for evaluating coulombic efficiency were stacked in this order from the positive electrode side, and after injecting electrolyte 1, the resultant was vacuum laminated to prevent oxygen from entering, thereby producing a lithium-ion battery for use in charge-discharge tests.

[0063] <Charge / Discharge Test: Measurement of Initial Coulomb Efficiency> The initial performance of the lithium ion battery was evaluated at 25°C using a charge / discharge measuring device "HJ-SD8" (manufactured by Hokuto Denko Corporation) according to the following method. Using the constant current constant voltage charging method (also known as CCCV mode), the battery was charged to 0.0V at a current of 0.05C, and then maintained at 0.0V until the current reached 0.0025C. After a 10-minute break, the battery was discharged to 1.5V at a current of 0.05C. The charged capacity was defined as [initial charge capacity (mAh)], and the discharged capacity was defined as [initial discharge capacity (mAh)]. The initial coulombic efficiency was calculated using the following formula, and the results are shown in Tables 4 and 5. [Initial coulomb efficiency (%)] = [Initial discharge capacity] ÷ [Initial charge capacity] × 100

[0064] <Evaluation of rate characteristics> The fabricated lithium-ion battery was placed in a thermostatic chamber (Espec Corp., PFU-3K) set to 25°C and charged in this state using a charge / discharge device (Hokuto Denko Corp., HJ0501SM8A). The charging current was set to 0.05C, and the battery was charged using CCCV charging (constant current / constant voltage mode) up to a cut-off voltage of 4.2V. It was then discharged at a constant current of 0.05C down to a cut-off voltage of 2.5V.

[0065] The lithium-ion battery that had undergone the initial charge / discharge process above was subjected to a second charge / discharge cycle. During this process, the discharge rate was a constant current discharge of 0.1C, and the charge rate was 0.1C for the second cycle, 0.2C for the third cycle, 0.5C for the fourth cycle, and 1.0C for the fifth cycle, with the rate repeated from the sixth cycle onwards up to 2.0C, 3.0C, 4.0C and 5.0C. When checking the capacity at each rate, CCCV charge / discharge was performed at 0.05C, as in the initial charge / discharge. As the results of the rate characteristics, the charge capacity and discharge capacity measured at 5.0 C are shown in Tables 4 and 5 (both are capacity ratios (%) at 0.1 C). The higher the ratio of charge capacity to discharge capacity at 0.1C, the better the rate characteristics.

[0066] [Table 4]

[0067] [Table 5]

[0068] Tables 4 and 5 show that the electrodes of each Example have a shorter electrolyte penetration time, a higher initial coulomb efficiency, and superior rate characteristics compared to the electrodes of each Comparative Example. For example, comparing Example 3 and Comparative Example 1, which use the same electrode active material and electrolyte system, the electrode density of Example 3 is 1.77 g / ml and the electrode density of Comparative Example 1 is 1.68 g / ml, meaning that Example 3 has a higher electrode density, but the electrolyte penetration time was 1.25 minutes for Example 3 and 40 minutes for Comparative Example 1. In addition, the coulomb efficiency was 82% for Example 3 and 80% for Comparative Example 1.

Claims

1. An electrode composition for a lithium ion battery containing a compound (A) which is an alkylene oxide adduct of an alkyl alcohol, The compound (A) contains a compound in which the alkylene oxide contains ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide in the alkylene oxide is 85% or more based on the total number of moles of the alkylene oxide; The electrode composition for a lithium ion battery, wherein the compound (A) has an HLB value of 11.5 to 18.

0.

2. the average number of moles of alkylene oxide added is 6 to 40; The electrode composition for a lithium ion battery according to claim 1 .

3. 2. The electrode composition for lithium ion batteries according to claim 1, wherein the content of the compound (A) is 0.001 to 2% by weight based on the weight of the electrode composition for lithium ion batteries.

4. 2. The electrode composition for a lithium ion battery according to claim 1, wherein the alkyl group of the alkyl alcohol has 8 to 17 carbon atoms.

5. A lithium ion battery electrode comprising the lithium ion battery electrode composition according to any one of claims 1 to 4.

6. A lithium ion battery comprising the lithium ion battery electrode according to claim 5.

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