KR101762477B1 - Negative electrode slurry and secondary battery prepared therefrom - Google Patents

Abstract

One embodiment of the present invention relates to a water-based negative electrode slurry comprising a negative electrode active material, a thickener, a binder, and an organic acid.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a negative electrode slurry and a secondary battery made from the negative electrode slurry,

One embodiment of the present invention relates to a negative electrode slurry and a secondary battery produced therefrom.

Recent trends in electronic industry development can be summarized as device's wireless, mobile trend and analog to digital conversion. Rapid dissemination of wireless phones (aka mobile phones) and notebook computers, and the transition from analog cameras to digital cameras are examples of this. Along with this tendency, research and development of a secondary battery as an operation power source of a device is actively proceeding.

The secondary battery has a structure in which a positive electrode / separator / negative electrode assembly is embedded in a sealed container together with an electrolyte. Generally, the manufacturing process of an electrode (anode or cathode) for a secondary battery includes a process of applying an electrode slurry prepared by mixing a common electrode active material with a binder, water or an organic solvent onto a metal foil of a thin plate in an appropriate amount and thickness and drying the electrode slurry do. The electrode slurry often retains water (H ₂ O) even after drying, and particularly in the case of an electrode material having a porous or hydrophilic surface such as hard carbon, even in a relatively dry environment in which an electrochemical device is assembled, moisture (H ₂ O) is high, moisture (H ₂ O) is present in the electrode material.

As described above, the water (H ₂ O) contained in the electrode during the manufacturing process or in terms of the material characteristics reacts with the fluorine component in the electrolyte dissolved in the electrolyte to form hydrofluoric acid and the formed hydrofluoric acid dissolves the cathode active material, Thereby deteriorating the performance of the secondary battery. In addition, in the case of a secondary battery, the water (H ₂ O) present in the electrode reacts with lithium to generate hydrogen gas, thereby increasing the pressure inside the secondary battery and causing a risk of explosion, .

Korean Patent No. 10-0354948

An object of the present invention is to provide an anode slurry capable of minimizing the content of residual water (H ₂ O) in a cathode and a secondary battery manufactured therefrom .

According to an aspect of the present invention, there is provided an aqueous negative electrode slurry including a negative electrode active material, a thickener, a binder, and an organic acid.

In another embodiment of the present invention, there is provided a method for preparing a water-based negative electrode slurry by mixing a negative electrode active material, a thickener, a binder, an organic acid anhydride, and a solvent.

In another embodiment of the present invention, there is provided a negative electrode comprising a negative electrode active material, a thickener, a binder, and an organic acid anhydride.

In another embodiment of the present invention, there is provided a method for producing a negative electrode slurry, comprising the steps of: preparing a negative electrode slurry by mixing a negative electrode active material, a thickener, a binder, an organic acid anhydride and a solvent; And drying the negative electrode current collector coated with the negative electrode slurry.

In still another embodiment of the present invention, there is provided a secondary battery comprising a cathode, a separator, and an anode including an organic acid.

The secondary battery including a cathode, a separator, and an anode including an organic acid anhydride according to an embodiment of the present invention may generate water (H ₂ O) upon charge and discharge, and the water (H ₂ O) The organic acid anhydride can be converted to an organic acid. As described above, the organic acid anhydride included in the secondary battery reacts with moisture (H ₂ O) generated in the secondary battery and is converted into an organic acid. In this process, water (H ₂ O) H ₂ O) content can be minimized. If the content of residual water (H ₂ O) in the secondary battery is minimized, generation of gas due to residual water (H ₂ O) can be minimized and the swelling phenomenon can be reduced. Thus, the stability and life characteristics of the secondary battery can be improved. Also, since the side reaction during the charging / discharging process after the manufacture of the secondary battery is reduced, the performance of the secondary battery such as the discharge capacity and initial efficiency of the secondary battery can be improved.

FIG. 1 is a graph showing a result of measuring the amount of generated gas according to Experimental Example 2 of the present invention. FIG.
2 is a graph showing the swelling measurement results of the secondary battery according to Experimental Example 3 of the present invention.

Hereinafter, the present invention will be described in more detail.

An embodiment of the present invention relates to a water-based negative electrode slurry comprising a negative electrode active material, a thickener, a binder, and an organic acid.

The aqueous anode slurry may be prepared by mixing a negative electrode active material, a thickener, a binder, an organic acid anhydride, and a solvent, and the organic acid anhydride may be converted into an organic acid by the solvent to be included in the aqueous negative electrode slurry. In addition, the aqueous negative electrode slurry containing the organic acid may be converted into an organic acid anhydride and coated on the negative electrode collector and then incorporated into the negative electrode.

The secondary battery including the organic acid anhydride, the separator, and the anode may generate water (H ₂ O) upon charge and discharge and may be converted into organic acid by the water (H ₂ O). As described above, the organic acid anhydride included in the secondary battery reacts with moisture (H ₂ O) generated in the secondary battery and is converted into an organic acid. In this process, water (H ₂ O) H ₂ O) content can be minimized.

If the content of residual water (H ₂ O) in the secondary battery is minimized, generation of gas due to residual water (H ₂ O) can be minimized and the swelling phenomenon can be reduced. Thus, the stability and life characteristics of the secondary battery can be improved. Also, the side reaction during the charging / discharging process after the manufacture of the secondary battery is reduced, so that the performance of the secondary battery such as the discharging capacity and the initial efficiency of the secondary battery can be improved.

The side reaction in the charging and discharging process of the secondary battery reacts with the fluorine component in the salt in which the water (H ₂ O) contained in the cathode is dissolved in the electrolyte to form hydrofluoric acid, and the formed hydrofluoric acid reacts with the surface reaction such as dissolving the cathode active material Thereby reducing the performance of the secondary battery.

The water-based negative electrode slurry may include a negative electrode active material, a thickener, a binder, and an organic acid. Generally, a water-based negative electrode slurry is prepared in the form of a slurry by adding a negative electrode active material or the like to a solvent, .

Typical examples of the negative electrode active material contained in the water-based slurry include amorphous carbon such as graphite carbon and non-graphitized carbon, and carbonaceous carbon such as non-graphitized carbon, and other LixFe ₂ O ₃ (0? X? 1), LixWO _{2 (0≤x≤1), Sn x Me 1} - x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1 of the Periodic Table, Group 2, 3 Group element, halogen, 0 < x &lt;1; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used. However, the present invention is not limited to these materials, and any negative electrode active material conventionally used may be used without limitation.

The water-based negative electrode slurry may contain 89 to 99% by weight of the negative electrode active material. When the negative electrode active material is less than 89% by weight, the capacity and life characteristics of the secondary battery including the negative electrode active material may be significantly reduced. When the content is more than 10% by weight, the content of the conductive material and the binder is relatively decreased, so that the conductivity of the negative electrode including the negative electrode active material and the adhesion force between the negative electrode active material and the negative electrode collector may be reduced.

The thickening agent is a component which assists the bonding of the negative electrode active material with the conductive material and the bonding force to the negative electrode current collector, and the thickening agent according to one embodiment of the present invention may be an aqueous thickener.

The water-based thickening agent is preferably CMC (Carboxyl Methyl Cellulose), but can be used without limitation as long as it is usually used as an aqueous thickener. The aqueous negative electrode slurry may contain the aqueous thickener in an amount of 1.0 to 5.0% by weight.

The binder is a component that assists in bonding between the negative electrode active material and the conductive material and bonding to the current collector. The binder according to an embodiment of the present invention may be an aqueous binder. Examples thereof may include one or more selected from the group consisting of acrylonitrile-butadiene rubber, styrene butadiene rubber (SBR), acrylic rubber, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinylidene fluoride, Preferably styrene butadiene rubber (SBR).

The water-based negative electrode slurry may contain an aqueous binder in an amount of 1.0 to 5.0% by weight. If the amount of the aqueous binder is less than 1.0% by weight, the bond between the negative electrode active material and the conductive material and the binding force with respect to the current collector may be deteriorated, If the amount is more than 5.0% by weight, the negative electrode active material may be relatively decreased, and the capacity and life characteristics of the secondary battery may be deteriorated.

The aqueous negative electrode slurry according to an embodiment of the present invention may include an organic acid together with a negative electrode active material, a thickener, and a binder, and the organic acid may be uniformly dispersed or non-uniformly dispersed in the aqueous negative electrode slurry.

The aqueous anode slurry may be prepared by mixing a negative electrode active material, a thickener, a binder, an organic acid anhydride, and a solvent, and the organic acid anhydride may be converted into an organic acid by the solvent to be included in the aqueous negative electrode slurry.

Further, in the step of applying the aqueous negative electrode slurry containing the organic acid to the negative electrode current collector and then drying the organic negative electrode slurry, the organic acid may be converted into the organic acid anhydride and included in the negative electrode.

The secondary battery including the organic acid anhydride, the separator, and the anode may generate water (H ₂ O) upon charge and discharge and may be converted into organic acid by the water (H ₂ O). As described above, the organic acid anhydride included in the secondary battery reacts with moisture (H ₂ O) generated in the secondary battery and is converted into an organic acid. In this process, water (H ₂ O) H ₂ O) content can be minimized.

If the content of residual water (H ₂ O) in the secondary battery is minimized, generation of gas due to residual water (H ₂ O) can be minimized and the swelling phenomenon can be reduced. Thus, the stability and life characteristics of the secondary battery can be improved. Also, the side reaction during the charging / discharging process after the manufacture of the secondary battery is reduced, so that the performance of the secondary battery such as the discharging capacity and the initial efficiency of the secondary battery can be improved.

The organic acid contained in the aqueous anode slurry may be selected from the group consisting of acetic acid, fumaric acid, maleic acid, phthalic acid, oxalic acid, succinic acid, tartaric acid, acid, glutamic acid, and glutaric acid, and may be maleic acid, preferably maleic acid.

The organic acid may include 0.1 to 5% by weight, and preferably 0.5 to 3% by weight based on the total weight of the negative electrode active material, the thickener, and the binder. When the amount of the organic acid is less than 0.1 wt%, the amount of moisture (H ₂ O) generated during charging and discharging of the secondary battery is insufficient, so that it is difficult to minimize the content of residual water (H ₂ O) in the secondary battery. If the organic acid is contained in an amount exceeding 5% by weight, there may be difficulties in the manufacturing process and the manufacturing cost may increase.

In some cases, the water-based negative electrode slurry may further contain a conductive material, a filler, and the like.

At this time, the conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the secondary battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, Ketjen black, channel black, panes black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as fluorocarbon, aluminum and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The conductive material may be contained in an amount of 1.0 to 30% by weight based on the total weight of the water-based negative electrode slurry. When the conductive material is less than 0.1% by weight, the amount of the conductive material may be insufficient and it may be difficult to impart conductivity between the anode active material and the anode current collector. When the conductive material is more than 30% by weight, The capacity and life characteristics of the battery may be deteriorated.

The filler may be used as a component for suppressing the expansion of the negative electrode, and is not particularly limited as long as it is a fibrous material without causing chemical changes in the secondary battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fiber, carbon fiber and the like can be used.

Another embodiment of the present invention provides a method for producing the aqueous negative electrode slurry by mixing the negative electrode active material, the thickener, the binder, the organic acid anhydride, and the solvent.

The aqueous negative electrode slurry may be prepared in the form of a slurry by adding a negative electrode active material, a thickener, a binder, and an organic acid anhydride to a solvent.

The organic acid anhydride may be selected from the group consisting of acetic anhydride, maleic anhydride, phthalic anhydride, oxalic anhydride, succinic anhydride, tartaric anhydride, Glutamic acid anhydride, glutamic anhydride, and glutaric acid anhydride.

The organic acid anhydride may include from 0.1 to 5% by weight, and preferably from 0.5 to 3% by weight, based on the total weight of the negative electrode active material, the thickener, and the binder. When the amount of the organic acid anhydride is less than 0.1% by weight, the amount of water (H ₂ O) generated during charging and discharging of the secondary battery is insufficient, so that it is difficult to minimize the content of residual water (H ₂ O) in the secondary battery If the organic acid anhydride is contained in an amount of more than 5% by weight, there may be difficulties in the manufacturing process and the manufacturing cost may increase.

The solvent may allow the preparation of a water-based negative electrode slurry by mixing the negative electrode active material, the thickener, the binder, and the organic acid anhydride, and the solvent may be aqueous-based. The water-based solvent is not only water but also alcohol such as isopropyl alcohol, methyl alcohol, ethyl alcohol, t-butyl alcohol, And cyclic amides such as N-methyl pyrrolidone may be used in an amount of not more than 40% by weight based on water.

The organic acid anhydride included in the aqueous negative electrode slurry may be converted into an organic acid by the solvent, and the organic acid anhydride may be converted into an organic acid after being mixed with the solvent to be included in the aqueous negative electrode slurry.

Another embodiment of the present invention provides a negative electrode comprising a negative electrode active material, a thickener, a binder, and an organic acid anhydride.

The negative electrode may be prepared by coating an aqueous negative electrode slurry prepared by mixing a negative electrode active material, a thickener, a binder, an organic acid anhydride, and a solvent on an anode current collector, followed by drying.

The organic acid anhydride included in the aqueous negative electrode slurry may be converted into an organic acid by the solvent, and the organic acid anhydride may be converted into an organic acid after being mixed with the solvent to be included in the aqueous negative electrode slurry. The negative electrode according to an embodiment of the present invention may further convert the organic acid to an organic acid anhydride in the step of applying the aqueous negative electrode slurry containing the organic acid to the negative electrode current collector and then drying the organic negative electrode slurry and the converted organic acid anhydride is included in the negative electrode .

According to another embodiment of the present invention, there is provided a method for manufacturing a negative electrode slurry, comprising the steps of: preparing a negative electrode slurry by mixing a negative electrode active material, a thickener, a binder, an organic acid anhydride and a solvent; And drying the coated negative electrode current collector.

The negative electrode is prepared by applying an aqueous negative electrode slurry on the negative electrode collector and then drying the negative electrode. The negative electrode may be manufactured by a manufacturing method commonly used in the art. For example, a water-based negative electrode slurry according to an embodiment of the present invention may be prepared, applied to a current collector, dried and compressed to produce a negative electrode.

The organic acid anhydride included in the aqueous negative electrode slurry may be converted into an organic acid by the solvent, and the organic acid anhydride may be converted into an organic acid after being mixed with the solvent to be included in the aqueous negative electrode slurry. The negative electrode according to an embodiment of the present invention may further convert the organic acid to an organic acid anhydride in the step of applying the aqueous negative electrode slurry containing the organic acid to the negative electrode current collector and then drying the organic negative electrode slurry and the converted organic acid anhydride is included in the negative electrode .

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. The negative electrode current collector is not particularly limited as long as it has electrical conductivity without causing chemical change in the secondary battery. Examples of the negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver or the like, aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

After the aqueous negative electrode slurry is applied to the negative electrode collector, the negative electrode collector coated with the aqueous negative electrode slurry can be dried. The drying may be carried out by air drying or vacuum drying, but any drying method conventionally used in the production of a negative electrode may be used without limitation.

Another embodiment of the present invention provides a secondary battery comprising a negative electrode including an organic acid, a separator, and a positive electrode.

By the secondary battery may be produced water (H ₂ O) during charging and discharging of the secondary battery, the water (H ₂ O) containing a negative electrode, a separator, and a positive electrode containing the organic acid anhydride is the acid anhydride Organic acid, and the converted organic acid may be included in the secondary battery.

As described above, the organic acid anhydride included in the secondary battery reacts with moisture (H ₂ O) generated in the secondary battery and is converted into an organic acid. In this process, water (H ₂ O) H ₂ O) content can be minimized.

If the content of residual water (H ₂ O) in the secondary battery is minimized, generation of gas due to residual water (H ₂ O) can be minimized and the swelling phenomenon can be reduced. Thus, the stability and life characteristics of the secondary battery can be improved. Also, the side reaction during the charging / discharging process after the manufacture of the secondary battery is reduced, so that the performance of the secondary battery such as the discharging capacity and the initial efficiency of the secondary battery can be improved.

The secondary battery generally comprises an electrode assembly in which a cathode and an anode are stacked with a separator interposed therebetween, and a non-aqueous electrolyte containing a lithium salt.

The positive electrode is prepared by applying a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, and drying the mixture. Optionally, a filler may be further added to the mixture.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + y} Mn _{2 - y} O ₄ (where y is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula LiNi _{1 -y} M _y O ₂ (where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, y = 0.01 to 0.3) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2 - y M y O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, y = 0.01 to 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The binder is a component that assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode collector is not particularly limited as long as it has high conductivity without causing chemical change in the secondary battery. For example, the positive electrode collector may be made of stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel Surface-treated with carbon, nickel, titanium, silver, or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m, and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The lithium salt-containing nonaqueous electrolyte solution is composed of an electrolyte solution and a lithium salt. As the electrolyte solution, a nonaqueous organic solvent, an organic solid electrolyte, and an inorganic solid electrolyte may be used. Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiBF ₄ , LiBF ₄ , LiBF ₄ , , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic carboxylate lithium, 4-phenylborate lithium, have.

For the purpose of improving the charge / discharge characteristics and the flame retardancy, the electrolytic solution is preferably mixed with an organic solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

Example

(Example)

(a) Preparation of water-based negative electrode slurry

Based on the total weight of the artificial graphite, CMC, and SBR binder, 96 weight% of artificial graphite, 1.5 weight% of CMC, 2 weight% of an SBR binder and 0.5 weight% of a conductive material and 2 weight% And mixed to prepare a water-based negative electrode slurry.

(b) Preparation of negative electrode

The aqueous slurry prepared in the step (a) was coated on a copper (Cu) foil, dried and rolled to prepare a negative electrode.

(c) Preparation of positive electrode

A positive electrode slurry was prepared by adding 95% by weight of LiCoO ₂ , 3% by weight of Super-P (conductive material) and 2% by weight of an SBR-based binder as a positive electrode active material to a mixed solvent of water and ethanol, Dried, and then rolled to prepare a positive electrode.

(d) Production of secondary battery

After the polyolefin separator was interposed between the anode and the cathode prepared in the above steps (b) and (c), the electrolyte was injected to prepare a secondary battery. As the electrolyte solution, 1M LiPF ₆ -containing EC / EMC system solution was used.

(Comparative Example)

A secondary battery was produced in the same manner as in Example except that maleic acid was not added in the preparation of the aqueous negative electrode slurry.

Experimental Example

(Experimental Example 1: Determination of Residual Water Content)

The moisture of the electrodes prepared in the above Examples and Comparative Examples was measured using a K / F moisture meter (Model: KMC-610), and the measured results are shown in Table 1 below.

Example Comparative Example Residual moisture content (ppm) 200 ppm 400 ppm

As can be seen in Table 1, the water content of the Examples was 200 ppm after drying the electrode, whereas 400 ppm of water was detected in the Comparative Example containing no organic acid. That is, when the organic acid is included in the cathode, it is confirmed that the amount of residual water in the cathode is reduced.

(Experimental Example 2: Measurement of Gas Emission)

In order to investigate the amount of gas generated in the secondary batteries manufactured in the examples and the comparative examples, the battery was charged at 0.1 C up to 4.2 V under constant current / constant voltage (CC / CV) condition at 25 ° C., Lt; / RTI &gt; After that, it was allowed to stand for 10 minutes, and discharged at 0.1 C up to 2.75 V, and the amount of generated gas was measured.

FIG. 1 shows the result of gas production measured by the above method.

In other words, when comparing the entire amount of gas generated with reference to FIG. 1, the amount of gas of about 30 ㎕ is measured in the case of the secondary battery of the comparative example, while the amount of gas of about 15 인 Was measured. In particular, the secondary battery of the embodiment has a hydrogen gas loss of 10 mu l or more as compared with the secondary battery of the comparative example, which can be judged as a result of the organic acid effectively controlling the moisture in the battery by the gas coming out from the reaction with water.

(Experimental Example 3: Swelling measurement of secondary battery)

In order to examine the swelling of the secondary battery manufactured in the above Examples and Comparative Examples, the battery was charged at 0.7 C up to 4.2 V under a constant current / constant voltage (CC / CV) condition at 25 ° C., Lt; / RTI &gt; Thereafter, the sample was allowed to stand for 10 minutes and discharged at 0.4 C to 2.75 V to measure the swelling.

The result of gas production measured by the above method is shown in Fig.

In other words, comparing FIG. 2, it can be seen that the swellings are significantly superior to the secondary battery of the embodiment containing the organic acid. That is, the secondary battery of the comparative example without addition of the organic acid showed about 7% expansion in 40 cycles, while the secondary battery of the example in which the organic acid was added showed an expansion of about 5% at 40 cycles and 2% Could know. As the cycle progresses, the generation of gas is intensified, so that the difference in swelling between the secondary battery of the embodiment and the secondary battery of the comparative example is expected to be further widened.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will readily appreciate that many suitable modifications and variations are possible in light of the above teachings. Accordingly, all such modifications and variations as fall within the scope of the present invention should be considered.

Claims (15)

delete delete delete delete delete delete The negative electrode active material, the thickener, the binder, the organic acid anhydride and the solvent were mixed
Characterized in that said organic acid anhydride is converted into an organic acid by said solvent
A negative electrode active material, a thickener, a binder, and an organic acid. delete The method of claim 7,
Wherein the organic acid anhydride includes one or more selected from the group consisting of acetic anhydride, maleic anhydride, phthalic anhydride, oxalic anhydride, succinic anhydride, tartaric anhydride, glutamic anhydride and glutaric anhydride. A method for producing an anode slurry. The method of claim 7,
Wherein the solvent comprises at least one selected from the group consisting of water, isopropyl alcohol, methyl alcohol, ethyl alcohol, and t-butyl alcohol. delete Preparing a water-based negative electrode slurry by mixing a negative electrode active material, a thickener, a binder, an organic acid anhydride, and a solvent;
Applying the aqueous negative electrode slurry to an anode current collector; And
Drying the negative electrode current collector coated with the aqueous negative electrode slurry;
Lt; / RTI &gt;
Wherein the organic acid anhydride in the aqueous aqueous slurry preparation step is converted into an organic acid by the solvent and the converted organic acid is converted into an organic acid anhydride in the step of drying the negative electrode current collector. delete delete delete

Images