Negative electrode active material, negative electrode slurry, negative electrode, and secondary battery

Abstract

The present invention relates to a negative electrode active material, a negative electrode slurry, a negative electrode comprising same, and a secondary battery comprising the negative electrode, the negative electrode active material comprising a silicon-carbon composite, a carbon layer provided on at least a portion of the silicon-carbon composite, and a coating layer of a catechol derivative or a gallol derivative provided on at least a portion of at least one of the silicon-carbon composite and the carbon layer.

Description

Negative active material, negative slurry, negative electrode and secondary battery

[0001] The present invention relates to a negative electrode active material, a negative electrode slurry, a negative electrode including the negative electrode slurry, and a secondary battery including the negative electrode.

[0002] This application claims the benefit of Korean Patent Application No. 10-2023-0147407, filed with the Korean Intellectual Property Office on October 31, 2023, the entire contents of which are incorporated herein by reference.

[0003] Due to the rapid increase in fossil fuel use, the demand for alternative or clean energy is increasing, and as part of this, the most actively researched field is power generation and storage using electrochemical reactions.

[0004] Secondary batteries are a prime example of electrochemical devices that utilize this electrochemical energy, and their applications are expanding. With the recent technological development and increasing demand for portable devices such as laptops, mobile phones, and cameras, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which boast high energy density and high capacity, have been extensively studied and are now commercialized and widely used.

[0005] In general, secondary batteries are composed of a cathode, an anode, an electrolyte, and a separator. The anode includes an anode active material that enables the insertion and deintercalation of lithium ions from the anode. Graphite is mainly used as the anode active material for lithium secondary batteries, but graphite has a low capacity per unit mass of 372 mAh / g, making it difficult to achieve high capacity in lithium secondary batteries. Accordingly, non-carbonaceous anode materials with higher energy density than graphite, such as silicon, tin, and their oxides, are being developed to achieve high capacity in lithium secondary batteries. However, these non-carbonaceous anode materials have a large capacity, but low initial efficiency, which leads to a large lithium consumption during initial charge and discharge, and a large irreversible capacity loss.

[0006] [Prior Art Literature]

[0007] (Patent Document 1) Patent Publication No. 10-2019-0129017

[0008] The present invention aims to provide a negative electrode active material, a negative electrode slurry, and a negative electrode and a secondary battery including the same, which can improve initial efficiency or life characteristics, lower the viscosity of slurry, and improve gas generation problems when applied to a secondary battery.

[0009] One embodiment of the present invention provides a negative active material comprising: a silicon-carbon composite; a carbon layer provided on at least a portion of the silicon-carbon composite; and a coating layer of a catechol derivative or a gallic acid derivative provided on at least a portion of at least one of the silicon-carbon composite and the carbon layer.

[0010] One embodiment of the present invention provides a method for producing a negative electrode active material, comprising the steps of forming a carbon layer on at least a portion of a silicon-carbon composite; and forming a coating layer of a catechol derivative or a gallic acid derivative on at least a portion of at least one of the silicon-carbon composite and the carbon layer.

[0011] One embodiment of the present invention provides a negative electrode active material including a silicon carbon composite and a coating layer of a catechol derivative or galrol derivative provided on at least a portion of the silicon carbon composite; and a negative electrode slurry including a catechol derivative or galrol derivative additive.

[0012] One embodiment of the present invention provides a negative electrode including a negative electrode current collector; and a negative electrode active material layer including the negative electrode slurry or a cured or polymerized product thereof provided on at least one surface of the negative electrode current collector.

[0013] One embodiment of the present invention provides a secondary battery including the negative electrode; a separator; and a positive electrode.

[0014] One embodiment of the present invention provides a battery module including the secondary battery and a battery pack including the same.

[0015] One embodiment of the present invention provides a battery pack including the secondary battery.

[0016] The negative active material according to the embodiments of the present invention achieves high capacity and high efficiency by using a silicon carbon composite as a core material of the negative active material, and at the same time, by including a carbon layer and a coating layer of a catechol derivative or a gallic acid derivative, it can prevent the problem of silicon coming into contact with water and generating gas in an aqueous process.

[0017] In addition, the negative electrode slurry according to the embodiments of the present invention can control volume expansion by including a negative electrode active material and a catechol derivative or galol derivative additive. Specifically, by using a coating layer of a catechol derivative or galol derivative within the negative electrode active material and a catechol derivative or galol derivative additive together, the adhesive strength between the negative electrode active material and the binder is increased through three-dimensional bonding with the binder, thereby suppressing volume expansion and improving life characteristics.

[0018] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0019] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0020] The terms used in this specification are used solely to describe exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0021] It should be understood that the terms “include,” “comprising,” or “having” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0022] In this specification, when it is said that a member is located “on” another member, this includes not only cases where the member is in contact with the other member, but also cases where another member exists between the two members.

[0023] In this specification, the presence or absence of elements and the content of elements in the negative active material can be confirmed through ICP analysis, and the ICP analysis can be performed using an inductively coupled plasma optical emission spectrometer (ICPAES, Perkin-Elmer 7300).

[0024] In this specification, the average particle diameter (D 50 ) can be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve. The average particle size (D 50) can be measured, for example, using a laser diffraction method. The laser diffraction method can generally measure particle diameters from the submicron range to several mm, and can obtain results with high reproducibility and high resolution.

[0025] The above average particle diameter (D 50 ) can be measured using a Microtrac device (manufacturer: Microtrac model number: S3500) using water and triton-X100 dispersant. Specifically, the average particle diameter (D) of the positive electrode active material particles 50 ) can be measured in the range of refractive index 1.5 to 1.7, and the negative active material can be measured under the condition of refractive index 1.97 or 2.42. For example, after dispersing the particles in a dispersion medium, the particles can be introduced into a commercially available laser diffraction particle size measuring device, irradiated with ultrasonic waves of about 28 kHz at an output of 60 W, and then a volume cumulative particle size distribution graph can be obtained, and then the particle size corresponding to 50% of the volume cumulative amount can be measured.

[0026] In this specification, the specific surface area of ​​the negative active material can be measured by the BET (Brunauer-Emmett-Teller; BET) method. For example, it can be measured by the BET 6-point method using a porosimetry analyzer (Bell Japan Inc, Belsorp-±) and a nitrogen gas adsorption flow method.

[0027]

[0028] <Cathode active material>

[0029] According to one embodiment of the present invention, a negative active material is characterized by including: a silicon-carbon composite; a carbon layer provided on at least a portion of the silicon-carbon composite; and a coating layer of a catechol derivative or a gallic acid derivative provided on at least a portion of at least one of the silicon-carbon composite and the carbon layer.

[0030] The above negative active material has a silicon carbon composite as its core. Since the coating layer of the catechol derivative or galrol derivative is formed after the formation of the carbon layer, it can be provided on the carbon layer, or it can be provided on the surface of the silicon carbon composite where the carbon layer is not provided. In addition, the coating layer of the catechol derivative or galrol derivative can completely cover the carbon layer, but can be formed only on a portion of the carbon layer, so both the carbon layer and the coating layer of the catechol derivative or galrol derivative can be observed on the surface of the negative active material.

[0031] When both the carbon layer and the coating layer of the catechol derivative or galol derivative are observed on the surface of the negative active material, the coating layer of the catechol derivative or galol derivative is located at the outermost layer, so that the functional group of the catechol derivative or galol derivative and the functional group of the binder interact through hydrogen bonding, thereby having the effect of improving the life performance.

[0032] Even when silicon is exposed on the surface of the silicon-carbon composite, the negative active material includes a carbon layer and a coating layer of a catechol derivative or a gallic acid derivative, thereby blocking contact of the exposed silicon with the outside, thereby improving the aqueous processability through a passivation effect.

[0033] In addition, the coating layer of the catechol derivative or gallic acid derivative can preferably form a polymer film on the surface of the carbon layer provided on at least a portion of the silicon carbon composite, and having a polymer film has an excellent effect of suppressing gas generation due to low solubility in water.

[0034] The above silicon-carbon composite is a composite of Si and C, in which Si and C (e.g., graphite) are each present. For example, the respective peaks of Si and C can be observed by an elemental analysis method such as XRD or NMR. In the present specification, the silicon-carbon composite may be expressed as Si / C. The silicon-carbon composite may be composed of Si and C that are not bonded to each other, but may include additional components as needed. For example, the silicon-carbon composite may or may not include silicon carbide, expressed as SiC. When the silicon-carbon composite includes silicon carbide, the content thereof is 3 wt% or less. The silicon-carbon composite may exist in a crystalline, amorphous, or mixed state thereof. According to one example, C in the silicon-carbon composite may exist in an amorphous state.

[0035] The above silicon carbon composite may be a Si / C-based active material.

[0036] The above silicon-carbon composite may be a composite of silicon and graphite, and may also form a structure in which a core composed of silicon and graphite is surrounded by graphene or amorphous carbon. In the above silicon-carbon composite, the silicon may be silicon nanoparticles.

[0037] The above silicon carbon composite includes porous carbon particles and silicon particles positioned on the surface or internal pores of the porous carbon particles.

[0038] As an example, the silicon carbon composite can be manufactured by a method including a step of etching carbon particles containing internal pores to expand the internal pores of the carbon particles; and a step of forming silicon particles on the surface and in the internal pores of the carbon particles having expanded internal pores.

[0039] The step of expanding the internal pores of the above carbon particles can be performed in a nitrogen (N2) atmosphere, an oxygen (O2) atmosphere, or an air atmosphere containing oxygen. Specifically, the flow rate of the oxygen (O2) or the air containing oxygen can be controlled to 0.1 to 10 L / min.

[0040] The step of expanding the internal pores of the above carbon particles can be performed at a temperature range of 400°C to 1200°C for 30 minutes to 4 hours.

[0041] Depending on the conditions for expanding the internal pores of the above carbon particles, the pore characteristics of the obtained porous carbon particles may vary.

[0042] The step of forming the above silicon particles can be performed using a chemical vapor deposition method. In this case, silicon nanoparticles are deposited on the surface and / or internal pores of the carbon-based particles with expanded internal pores, thereby forming a silicon coating layer in the form of a film, an island, or a mixture thereof.

[0043] According to one embodiment of the present invention, the catechol derivative comprises at least one selected from dopamine, norepinephrine and catechin, or a salt thereof or a polymer thereof, and the galol derivative comprises at least one selected from tannic acid, galolcatechin and galolcatechin gallate, or a salt thereof or a polymer thereof.

[0044] The catechol derivative may be present in the form of a hydrochloride salt, for example, dopamine hydrochloride or norepinephrine hydrochloride.

[0045] According to one embodiment of the present invention, the content of the coating layer of the catechol derivative or galrol derivative is 0.5 parts by weight or more and less than 5 parts by weight based on 100 parts by weight of the total negative electrode active material. Specifically, the coating layer of the catechol derivative or galrol derivative may be 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, or 1 part by weight or more, and less than 5 parts by weight, less than 4.9 parts by weight, less than 4.8 parts by weight, less than 4.7 parts by weight, less than 4.6 parts by weight, or less than 4.5 parts by weight based on 100 parts by weight of the total negative electrode active material.

[0046] When the coating layer of the above catechol derivative or galrol derivative satisfies the above range, a silicon carbon composite having a high capacity compared to the SiOx-based active material is included in an appropriate amount, thereby enabling a capacity balance with the positive electrode active material to be achieved, and preventing the problem of silicon coming into contact with water and generating gas in an aqueous process.

[0047] According to one embodiment of the present invention, the content of the carbon layer is 0.1 to 50 parts by weight based on 100 parts by weight of the total negative electrode active material. Specifically, the carbon layer may be included in an amount of 0.1 to 30 parts by weight, 0.1 to 20 parts by weight, 0.5 to 15 parts by weight, or 1 to 10 parts by weight based on 100 parts by weight of the total negative electrode active material.

[0048] When the above range is satisfied, the conductivity of the negative electrode active material is improved, and the volume change of the negative electrode active material during charging and discharging of the battery is easily suppressed, so that the life characteristics of the battery can be improved.

[0049] The above carbon layer can be formed by a chemical vapor deposition (CVD) method using at least one hydrocarbon gas selected from the group consisting of methane, ethane, and acetylene.

[0050] The above carbon layer may include at least one of amorphous carbon and crystalline carbon.

[0051] The above crystalline carbon can further improve the conductivity of the negative electrode active material. The above crystalline carbon can include at least one selected from the group consisting of fluorene, carbon nanotubes, and graphene.

[0052] The amorphous carbon can appropriately maintain the strength of the carbon layer, thereby suppressing expansion of the negative electrode active material. The amorphous carbon can be a carbon-based material formed using at least one carbide or hydrocarbon selected from the group consisting of tar, pitch, and other organic materials as a source for chemical vapor deposition.

[0053] The above-mentioned other organic carbonates may be carbonates of organic carbonates selected from sucrose, glucose, galactose, fructose, lactose, mannose, ribose, aldohexose or kedohexose and combinations thereof.

[0054] The hydrocarbon may be a substituted or unsubstituted aliphatic or alicyclic hydrocarbon, or a substituted or unsubstituted aromatic hydrocarbon. The aliphatic or alicyclic hydrocarbon may be methane, ethane, ethylene, acetylene, propane, butane, butene, pentane, isobutane, or hexane, etc. The aromatic hydrocarbon of the substituted or unsubstituted aromatic hydrocarbon may be benzene, toluene, xylene, styrene, ethylbenzene, diphenylmethane, naphthalene, phenol, cresol, nitrobenzene, chlorobenzene, indene, coumarone, pyridine, anthracene, or phenanthrene, etc.

[0055] According to one embodiment of the present invention, the average particle diameter (D) of the negative electrode active material 50 ) is 0.1 ㎛ to 30 ㎛. Specifically, it may be 1 ㎛ to 20 ㎛, 1 ㎛ to 10 ㎛, or 2 ㎛ to 10 ㎛. The average particle diameter (D of the negative electrode active material 50) satisfies the above range, the dispersibility of the active material is appropriate when manufacturing the negative electrode slurry, the structural stability of the active material is ensured during charge / discharge, and the problem of poor coating due to large particles during electrode coating is reduced. In addition, the problem of increased volume expansion / contraction level due to excessively large particle size can be prevented, and the problem of decreased initial efficiency due to excessively small particle size can be prevented.

[0056] According to one embodiment of the present invention, the BET specific surface area of ​​the negative active material is 20 m 2 / g or less, for example, 10m 2 / g or less is preferable. For example, the BET specific surface area of ​​the negative active material is 0.1 m 2 / g or more than 10m 2 / g or less, e.g. 1 m 2 / g to 8 m 2 / g or 4 m 2 / g to 6 m 2 / g. The specific surface area can be measured by the BET (Brunauer-Emmett-Teller; BET) method. For example, it can be measured by the BET six-point method using a porosimetry analyzer (Bell Japan Inc, Belsorp-Ⅱ mini) and a nitrogen gas adsorption flow method.

[0057]

[0058] <Method for manufacturing negative active material>

[0059] A method for manufacturing a negative electrode active material according to one embodiment of the present invention may include a step of forming a carbon layer on at least a portion of a silicon-carbon composite; and a step of forming a coating layer of a catechol derivative or a gallic acid derivative on at least a portion of at least one of the silicon-carbon composite and the carbon layer.

[0060] Before or after forming the above carbon layer, the particle size of the negative active material can be controlled by a grinding method such as a mechanical milling method as needed.

[0061] The step of forming a carbon layer on the surface of the negative active material can be performed by, for example, injecting a carbon-based raw material gas such as methane gas and performing heat treatment in a rotary tubular furnace. Specifically, the silicon-based oxide particles are introduced into a rotary tubular furnace, the temperature is increased to 800°C to 1,150°C, 900°C to 1,050°C, or 950°C to 1,000°C at a rate of 3 to 10°C / min, or at a rate of about 5°C / min, and while rotating the rotary tubular furnace, argon gas and carbon-based raw material gas are flowed, and heat treatment is performed for 30 minutes to 8 hours to form a carbon layer.

[0062] A step of forming a coating layer of a catechol derivative or a galrol derivative on at least a portion of one of the silicon carbon composite and carbon layers formed as described above is performed. The coating layer of the catechol derivative or the galrol derivative may be formed by an oxidative self-polymerization method in which a catechol derivative or a galrol derivative is added to a weakly basic solution to form a polymer. A solution such as tris-HCl buffer or bicine buffer may be used as the weakly basic solution, and the pH of the weakly basic solution may be 7.5 or more and 9 or less. Specifically, the lower pH limit of the weakly basic solution may be 7.5, 7.6, 7.7, 7.8, 7.9, or 8.0, and the upper pH limit of the weakly basic solution may be 9.0, 8.9, 8.8, 8.7, 8.6, or 8.5.

[0063] In order for the above oxidative self-polymerization reaction to occur well, the content of solids including catechol derivatives, galrol derivatives, and silicon carbon complexes is preferably 0.1 to 5%.

[0064]

[0065] <Cathode slurry>

[0066] According to one embodiment of the present invention, a negative electrode slurry comprises a negative electrode active material including a silicon carbon composite and a coating layer of a catechol derivative or a galrol derivative provided on at least a portion of the silicon carbon composite; and a catechol derivative or galrol derivative additive.

[0067] According to one embodiment of the present invention, a negative electrode slurry comprises a negative electrode active material including a silicon-carbon composite, a carbon layer provided on at least a portion of the silicon-carbon composite, and a coating layer of a catechol derivative or a gallic acid derivative provided on at least a portion of at least one of the silicon-carbon composite and the carbon layer; and a catechol derivative or gallic acid derivative additive.

[0068] The catechol derivative or galol derivative included in the coating layer provided on at least a portion of the above silicon carbon composite and the catechol derivative or galol derivative of the additive may be the same or different.

[0069] The above catechol derivative or galrol derivative is used as a coating layer and additive provided on at least a portion of the silicon carbon composite, thereby improving slurry stability, such as preventing viscosity reduction due to interaction between the coating layer and the additive.

[0070] According to one embodiment of the present invention, the content of the coating layer of the catechol derivative or galrol derivative in the negative electrode active material included in the negative electrode slurry is 0.5 parts by weight or more and less than 5 parts by weight based on 100 parts by weight of the total negative electrode active material. Specifically, the coating layer of the catechol derivative or galrol derivative may be 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, or 1.0 parts by weight or more, and may be less than 5 parts by weight, less than 4.9 parts by weight, less than 4.8 parts by weight, less than 4.7 parts by weight, less than 4.6 parts by weight, or less than 4.5 parts by weight based on 100 parts by weight of the total negative electrode active material.

[0071] When the coating layer of the above catechol derivative or galrol derivative satisfies the above range, a silicon carbon composite having a high capacity compared to the SiOx-based active material is included in an appropriate amount, thereby enabling a capacity balance with the positive electrode active material to be achieved, and preventing the problem of silicon coming into contact with water and generating gas in an aqueous process.

[0072] According to one embodiment of the present invention, the content of the catechol derivative or galrol derivative additive included in the negative electrode slurry is 0.01 to 0.5 parts by weight based on 100 parts by weight of the total solid content of the negative electrode slurry. Specifically, it may be 0.02 parts by weight or more, 0.03 parts by weight or more, 0.04 parts by weight or more, or 0.05 parts by weight or more, and 0.49 parts by weight or less, 0.48 parts by weight or less, 0.47 parts by weight or less, 0.46 parts by weight or less, or 0.45 parts by weight or less based on 100 parts by weight of the total solid content of the negative electrode slurry.

[0073] When the content of the above catechol derivative or galol derivative additive satisfies the above range, volume expansion can be controlled through three-dimensional bonding with the binder, and although the catechol derivative or galol derivative itself is an insulator, it can also function as a conductive material by changing into a material capable of conducting electricity during the first charge / discharge process.

[0074] According to one embodiment of the present invention, the negative electrode active material included in the negative electrode slurry has the carbon layer described above between the silicon carbon composite and the coating layer of a catechol derivative or gallic acid derivative provided on at least a portion of the silicon carbon composite.

[0075] According to one embodiment of the present invention, the content of the carbon layer is 0.1 to 50 parts by weight based on 100 parts by weight of the total negative electrode active material. Specifically, the carbon layer may be included in an amount of 0.1 to 30 parts by weight, 0.1 to 20 parts by weight, 0.5 to 15 parts by weight, or 1 to 10 parts by weight based on 100 parts by weight of the total negative electrode active material.

[0076] The above negative electrode slurry may further include an additional negative electrode active material.

[0077] As the above additional negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β(0 < β < 2), SnO2, vanadium oxide, lithium titanium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fiber-like forms, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.

[0078] The above additional negative electrode active material may be a carbon-based negative electrode active material.

[0079] The weight ratio of the negative electrode active material and the additional negative electrode active material included in the above negative electrode slurry may be 10:90 to 90:10, and specifically 10:90 to 50:50.

[0080] The above-described cathode slurry may include a solvent for forming the cathode slurry. Specifically, the solvent for forming the cathode slurry may include at least one selected from the group consisting of distilled water, ethanol, methanol, and isopropyl alcohol, specifically distilled water, in order to facilitate dispersion of the components.

[0081] A cathode slurry according to one embodiment of the present invention further includes a binder and a conductive material.

[0082] The above binder can play a role in improving the adhesion between negative electrode active materials and the adhesive strength between the negative electrode active materials and the negative electrode current collector. The binder may be one known in the art, and non-limiting examples thereof include at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and a material in which hydrogens thereof are substituted with Li, Na, Ca, etc., and may also include various copolymers thereof.

[0083] The above binder may be included in an amount of 0.1 to 50 parts by weight based on 100 parts by weight of the negative electrode active material layer, for example, preferably 0.3 to 35 parts by weight, more preferably 0.5 to 10 parts by weight.

[0084] The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, paneth black, lamp black, and thermal black; conductive fibers such as carbon fiber or metal fiber; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0085]

[0086] <Cathode>

[0087] According to one embodiment of the present invention, a negative electrode may include a negative current collector; and a negative active material layer comprising the negative electrode slurry or a cured or polymerized product thereof provided on at least one surface of the negative current collector. The negative active material layer may include the negative electrode active material, and the negative electrode active material may include the above-described negative electrode active material. Furthermore, the negative electrode active material layer may further include a binder and / or a conductive material.

[0088] The negative current collector may be any conductive material that does not cause a chemical change in the battery, and is not particularly limited thereto. For example, the current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like. Specifically, a transition metal that adsorbs carbon well, such as copper or nickel, may be used as the current collector. The current collector may have a thickness of 1 μm to 500 μm, but the thickness of the current collector is not limited thereto.

[0089]

[0090] Secondary battery

[0091] A secondary battery according to one embodiment of the present invention may include the aforementioned negative electrode. Specifically, the secondary battery may include a negative electrode, a positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte.

[0092] The positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and may include a positive electrode active material layer including the positive electrode active material. The positive electrode active material layer may include the positive electrode active material.

[0093] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and fine unevenness may be formed on the surface of the current collector to increase the adhesive strength of the positive electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0094] The above positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; or a compound having the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-c2 M c2Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Lithium manganese composite oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein, M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); LiMn2O4, etc., in which a part of Li in the chemical formula is replaced with an alkaline earth metal ion, but is not limited thereto. The positive electrode may be Li-metal.

[0095] The above-described positive electrode active material layer may include a positive electrode conductive material and a positive electrode binder together with the positive electrode active material described above.

[0096] At this time, the positive electrode conductive material is used to provide conductivity to the electrode, and in the battery to be constructed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one of these may be used alone or a mixture of two or more may be used.

[0097] In addition, the positive electrode binder plays a role of improving the adhesion between positive electrode active material particles and the adhesiveness between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof.

[0098] The positive electrode and the negative electrode can be manufactured according to a conventional method for manufacturing positive and negative electrodes, except that the positive and negative electrode active materials described above are used. Specifically, the composition for forming an active material layer, which includes the active material and optionally a binder and a conductive material, is applied to a current collector, followed by drying and rolling. At this time, the types and contents of the positive and negative electrode active materials, binder, and conductive material are as described above. The solvent may be a solvent generally used in the relevant technical field, and examples thereof include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, and water. One type alone or a mixture of two or more types thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the active material, conductive material, and binder in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity during subsequent coating for manufacturing the positive and negative electrodes. Additionally, in another method, the positive and negative electrodes may be manufactured by casting the composition for forming the active material layer on a separate support, and then laminating the resulting film on a current collector by peeling it off from the support.

[0099] The above separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in secondary batteries can be used without any particular restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0100] The above electrolyte may include, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0101] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0102] As the above non-aqueous organic solvent, for example, an aprotic organic solvent such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxy methane, dioxolan derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyrropionate, ethyl propionate, etc. can be used.

[0103] In particular, among the above carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with high dielectric constants and thus can be preferably used because they easily dissociate lithium salts. In addition, when low-viscosity, low-dielectric constant linear carbonates such as dimethyl carbonate and diethyl carbonate are mixed and used in an appropriate ratio with these cyclic carbonates, an electrolyte with high electrical conductivity can be produced, so that they can be used even more preferably.

[0104] The metal salt may be a lithium salt, and the lithium salt is a substance that is easily dissolved in the non-aqueous electrolyte, for example, the anion of the lithium salt is F - , Cl - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 -, CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - One or more selected from the group consisting of may be used.

[0105] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as, for example, a haloalkylene carbonate compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, a cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery.

[0106] According to one embodiment of the present invention, a battery module including the secondary battery as a unit cell and a battery pack including the same are provided. In addition, a battery pack including the secondary battery is provided. The battery module and the battery pack include the secondary battery having high capacity, high rate characteristics, and cycle characteristics. The secondary battery can be used as a power source for a medium- to large-sized device selected from the group consisting of an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage system.

[0107]

[0108] Hereinafter, preferred embodiments are presented to help understand the present invention, but the above embodiments are only illustrative of the present disclosure, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present disclosure, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

[0109]

[0110] < Manufacturing of negative active materials >

[0111] Example 1-1: Preparation of negative electrode active material

[0112] A 0.5 M sucrose aqueous solution was placed in an autoclave and reacted at 180°C for 24 hours to synthesize spherical particles. After the reaction, the obtained carbon particles were washed 2-3 times with ethanol. The carbon particles dried at 100°C for more than 12 hours and KOH were mixed in a 1:3 weight ratio and heated at 800°C for 2 hours in a nitrogen atmosphere to expand the pores. After washing with distilled water, the particles were dried at 100°C for more than 12 hours. The carbon particles were placed in the hot zone of the CVD device, and SiH4 / H2 = 5 / 95 gas was flowed at a flow rate of 50 ml / min at 600°C for 2 hours to produce a silicon / carbon composite. The silicon / carbon composite was placed in the hot zone of the CVD device, and methane was blown into the hot zone at 700°C using Ar as a carrier gas to react for 1 hour to form a carbon layer on the surface. Afterwards, tannic acid and a silicon / carbon composite were reacted in a weakly basic aqueous solution at a weight ratio of 5:95 at room temperature with stirring for 2 hours to manufacture a negative electrode active material including a carbon layer and a tannic acid coating layer on the surface of the silicon / carbon composite.

[0113]

[0114] Example 1-2: Preparation of negative electrode active material

[0115] A negative electrode active material was manufactured in the same manner as in Example 1-1, except that the weight ratio of tannic acid and silicon / carbon composite was 10:90 when manufacturing the negative electrode active material.

[0116]

[0117] Example 1-3: Preparation of negative electrode active material

[0118] A negative electrode active material was manufactured using the same method as Example 1-1, except that the process of forming a carbon layer was performed at 700°C for 2 hours during the manufacture of the negative electrode active material.

[0119]

[0120] Example 1-4: Preparation of negative electrode active material

[0121] A negative electrode active material was manufactured in the same manner as in Example 1-1, except that tannic acid was replaced with dopamine hydrochloride during the manufacture of the negative electrode active material.

[0122]

[0123] Comparative Example 1-1: Preparation of negative electrode active material

[0124] A negative electrode active material was manufactured in the same manner as in Example 1-1, except that a coating layer of a catechol derivative or a galrol derivative was not formed during the manufacture of the negative electrode active material.

[0125]

[0126] Comparative Example 1-2: Preparation of negative electrode active material

[0127] A negative electrode active material was manufactured in the same manner as in Example 1-1, except that the weight ratio of tannic acid and silicon / carbon composite was 30:70 when manufacturing the negative electrode active material.

[0128]

[0129] Comparative Example 1-3: Preparation of negative electrode active material

[0130] A negative electrode active material was manufactured in the same manner as in Example 1-1, except that a carbon layer was formed on a coating layer of a catechol derivative or a galrol derivative when manufacturing a negative electrode active material.

[0131]

[0132] Silicon carbon complex content (wt.%)Catechol derivative or gallic acid derivative coating layer content (wt.%)Carbon layer content (wt.%)Example 1-194.51.73.8Example 1-292.34.23.5Example 1-392.71.65.7Example 1-494.61.83.6Comparative example 1-195.904.1Comparative example 1-281.315.73.0Comparative example 1-395.30.74.0

[0133]

[0134] < Manufacture of cathode slurry >

[0135] Example 2-1: Preparation of cathode slurry

[0136] The negative electrode slurry of Example 2-1 was prepared by mixing the negative electrode active material and artificial graphite manufactured in Example 1-1 in a weight ratio of 2:8, carbon black as a conductive material, carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) as binders, and additive (tannic acid) with water as a solvent in a weight ratio of negative electrode active material: conductive material: binder (CMC): binder (SBR): additive (tannic acid) = 96.4:1:1:1.5:0.1.

[0137]

[0138] Example 2-2: Preparation of cathode slurry

[0139] The negative electrode slurry of Example 2-2 was prepared in the same manner as in Example 2-1, except that the negative electrode active material of Example 1-2 was used in the preparation of the negative electrode slurry.

[0140]

[0141] Example 2-3: Preparation of cathode slurry

[0142] The negative electrode slurry of Example 2-3 was prepared in the same manner as in Example 2-1, except that the negative electrode active material of Example 1-3 was used in the preparation of the negative electrode slurry.

[0143]

[0144] Comparative Example 2-1: Preparation of cathode slurry

[0145] The negative electrode slurry of Comparative Example 2-1 was prepared in the same manner as Example 2-1, except that the negative electrode active material of Comparative Example 1-1 was used in the preparation of the negative electrode slurry.

[0146]

[0147] Comparative Example 2-2: Preparation of cathode slurry

[0148] The negative electrode slurry of Comparative Example 2-2 was prepared in the same manner as Example 2-1, except that the negative electrode active material of Comparative Example 1-2 was used in the preparation of the negative electrode slurry.

[0149]

[0150] Comparative Example 2-3: Preparation of cathode slurry

[0151] The negative electrode slurry of Comparative Example 2-3 was prepared in the same manner as Example 2-1, except that the negative electrode active material of Comparative Example 1-3 was used in the preparation of the negative electrode slurry.

[0152]

[0153] Reference Example 2-1: Preparation of cathode slurry

[0154] The negative electrode slurry of Reference Example 2-1 was prepared in the same manner as Example 2-1 except that no tannic acid additive was used in the preparation of the negative electrode slurry.

[0155]

[0156] Reference Example 2-2: Preparation of cathode slurry

[0157] The negative electrode slurry of Reference Example 2-2 was prepared in the same manner as Example 2-1 except that 5 parts by weight of tannic acid additive was used when preparing the negative electrode slurry.

[0158]

[0159] < Evaluation of viscosity and gas generation of cathode slurry >

[0160] The manufactured cathode slurry was stored at room temperature for two days and then its viscosity was measured at 23°C using a rheometer (TA, HR 20). Specifically, the relative viscosity (%) of the cathode slurry after two days of storage at room temperature, based on the viscosity immediately after manufacturing the cathode slurry, is shown in Table 2 below.

[0161] Viscosity (%) = {Viscosity of cathode slurry after 2 days of storage / Viscosity immediately after cathode slurry production} x 100

[0162] Gas generation can be determined by placing 20 g of the aforementioned cathode slurry in a pouch, sealing it, storing it in a 40°C chamber for 7 days, and measuring the change in pouch volume. The amount of gas generated can be determined by placing the sealed pouch in water and measuring the change in water volume. The amount of gas generated is shown in Table 2 below.

[0163]

[0164] Viscosity (%) Gas generation amount (mL) after 7 days of storage at 40℃ Example 2-1968 Example 2-2944 Example 2-3944 Comparative Example 2-16248 Comparative Example 2-2956 Comparative Example 2-37833 Reference Example 2-1948 Reference Example 2-2948

[0165]

[0166] <Manufacturing of cathodes and lithium secondary batteries>

[0167] Example 3-1: Manufacturing of negative electrode and lithium secondary battery

[0168] The negative electrode slurry prepared in Example 2-1 was coated on one side of a copper current collector and dried. The temperature of the circulating air was 60°C. Subsequently, the negative electrode was manufactured by roll pressing and then punching to a certain size.

[0169] Li metal was used as a counter electrode, and a polyolefin separator was interposed between the negative electrode and the Li metal. Then, an electrolyte containing 1 M LiPF6 dissolved in a solvent containing ethylene carbonate (EC) and diethyl carbonate (DEC) mixed in a volume ratio of 30:70 was injected to manufacture the negative electrode and lithium secondary battery of Example 3-1.

[0170]

[0171] Example 3-2: Manufacturing of a cathode and lithium secondary battery

[0172] The negative electrode and lithium secondary battery of Example 3-2 were manufactured in the same manner as in Example 3-1, except that the negative electrode slurry of Example 2-2 was used.

[0173]

[0174] Example 3-3: Manufacturing of negative electrode and lithium secondary battery

[0175] The negative electrode and lithium secondary battery of Example 3-3 were manufactured in the same manner as in Example 3-1, except that the negative electrode slurry of Example 2-3 was used.

[0176]

[0177] Comparative Example 3-1: Manufacturing of a cathode and lithium secondary battery

[0178] The negative electrode and lithium secondary battery of Comparative Example 3-1 were manufactured in the same manner as in Example 3-1, except that the negative electrode slurry of Comparative Example 2-1 was used.

[0179]

[0180] Comparative Example 3-2: Manufacturing of a cathode and lithium secondary battery

[0181] The negative electrode and lithium secondary battery of Comparative Example 3-2 were manufactured in the same manner as in Example 3-1, except that the negative electrode slurry of Comparative Example 2-2 was used.

[0182]

[0183] Comparative Example 3-3: Manufacturing of a cathode and lithium secondary battery

[0184] The negative electrode and lithium secondary battery of Comparative Example 3-3 were manufactured in the same manner as in Example 3-1, except that the negative electrode slurry of Comparative Example 2-3 was used.

[0185]

[0186] Reference Example 3-1: Manufacturing of negative electrode and lithium secondary battery

[0187] The negative electrode and lithium secondary battery of Reference Example 3-1 were manufactured in the same manner as Example 3-1 except that the negative electrode slurry of Reference Example 2-1 was used.

[0188]

[0189] Reference Example 3-2: Manufacturing of a cathode and lithium secondary battery

[0190] The negative electrode and lithium secondary battery of Reference Example 3-2 were manufactured in the same manner as Example 3-1 except that the negative electrode slurry of Reference Example 2-2 was used.

[0191]

[0192] <Evaluation of discharge capacity, initial efficiency, and cycle characteristics of secondary batteries>

[0193] Charge and discharge were performed on the secondary batteries of Examples 3-1 to 3-3, Comparative Examples 3-1 to 3-3, and Reference Examples 3-1 and 3-2, and the discharge capacity, initial efficiency, and cycle characteristics were evaluated, which are listed in Table 3 below.

[0194] The batteries manufactured in Examples 3-1 to 3-3, Comparative Examples 3-1 to 3-3, and Reference Examples 3-1 and 3-2 were charged at 25°C with a constant current (CC) of 0.1 C until the voltage reached 5 mV, and then charged with a constant voltage (CV) until the charge current reached 0.005 C (cut-off current) for the first time. After leaving the batteries for 20 minutes, they were discharged with a constant current (CC) of 0.1 C until the voltage reached 1.5 V to confirm the initial efficiency.

[0195] Afterwards, the cycle characteristics were evaluated by measuring the capacity retention rate by repeating charge and discharge at 0.5 C for up to 40 cycles.

[0196] Based on the results of one charge / discharge cycle, the initial efficiency (%) was derived using the following calculation formula.

[0197] Initial efficiency (%) = {Discharge capacity of negative active material (mAh / g) / Charge capacity of negative active material (mAh / g)} × 100

[0198] The capacity retention rate was derived by the following calculation formula.

[0199] Capacity retention rate (%) = (40 discharge capacity / 1 discharge capacity) × 100

[0200]

[0201] Discharge capacity (mAh / g) Initial efficiency (%) Capacity retention rate (%) Example 3-119538993 Example 3-219018790 Example 3-319228791 Comparative example 3-119348884 Comparative example 3-217408176 Comparative example 3-319388888 Reference example 3-119108787 Reference example 3-218958580

[0202] From the results in Tables 2 and 3, in the case of Comparative Example 3-1, it was confirmed that the effect of suppressing gas generation by the coating layer film was small and the capacity retention rate was lowered compared to Examples 3-1 to 3-3 when the negative electrode slurry (Comparative Example 2-1) was prepared using the negative electrode active material (Comparative Example 1-1) that did not form a catechol derivative or galrol derivative coating layer.

[0203] In the case of Comparative Example 3-2, the amount of gas generated was small because the negative electrode active material (Comparative Example 1-2) was used in which the content of the coating layer of the catechol derivative or galrol derivative was added in an amount of 5 parts by weight or more based on 100 parts by weight of the total negative electrode active material, thereby making the coating layer very thick. However, since the coating layer is not a material that contributes to the initial efficiency and capacity retention rate, it was confirmed that the discharge capacity, initial efficiency, and capacity retention rate were lowered compared to Examples 3-1 to 3-3.

[0204] In the case of Comparative Example 3-3, when a negative electrode slurry (Comparative Example 2-3) was manufactured using a negative electrode active material (Comparative Example 1-3) in which a carbon layer was formed on a coating layer of a catechol derivative or a galrol derivative, it was confirmed that the coating layer of the catechol derivative or the galrol derivative did not properly perform its role of preventing contact with water, so that the effect of suppressing gas generation by the coating layer film was small, and accordingly, the processability was deteriorated, and the capacity retention rate was somewhat lowered compared to Examples 3-1 to 3-3.

Claims

1. Silicon carbon composite; a carbon layer provided on at least a portion of the silicon carbon composite; and A negative electrode active material comprising a coating layer of a catechol derivative or a gallic acid derivative provided on at least a portion of at least one of the silicon carbon composite and the carbon layer.

2. In claim 1, the catechol derivative comprises at least one selected from dopamine, norepinephrine and catechin, or a salt thereof or a polymer thereof, A negative electrode active material wherein the galol derivative comprises at least one selected from tannic acid, galol catechin and galol catechin gallate, or a salt thereof or a polymer thereof.

3. In claim 1, the content of the coating layer of the catechol derivative or galrol derivative is 0.5 parts by weight or more and less than 5 parts by weight based on 100 parts by weight of the total negative active material.

4. In claim 1, the content of the carbon layer is 0.1 to 50 parts by weight based on 100 parts by weight of the total negative electrode active material.

5. In claim 1, the average particle diameter (D) of the negative electrode active material 50 ) is a negative electrode active material having a diameter of 0.1㎛ to 30㎛.

6. A step of forming a carbon layer on at least a portion of the silicon carbon composite; and A method for producing a negative electrode active material, comprising the step of forming a coating layer of a catechol derivative or a gallic acid derivative on at least a portion of at least one of the silicon carbon composite and the carbon layer.

7. A negative active material comprising a silicon carbon composite and a coating layer of a catechol derivative or a gallic acid derivative provided on at least a portion of the silicon carbon composite; and A cathode slurry comprising a catechol derivative or galrol derivative additive.

8. In claim 7, a negative electrode slurry in which the content of the coating layer of the catechol derivative or galrol derivative is 0.5 parts by weight or more and less than 5 parts by weight based on 100 parts by weight of the total negative electrode active material.

9. In claim 7, the content of the catechol derivative or galrol derivative additive is 0.01 to 0.5 parts by weight based on 100 parts by weight of the total solid content of the cathode slurry.

10. In claim 7, the negative electrode slurry comprises a carbon layer between the silicon carbon composite and the coating layer of a catechol derivative or gallic acid derivative provided on at least a portion of the silicon carbon composite.

11. A negative electrode slurry according to claim 10, wherein the content of the carbon layer is 0.1 to 50 parts by weight based on 100 parts by weight of the total negative electrode active material.

12. A cathode slurry further comprising a binder and a conductive material according to claim 7.

13. A negative electrode comprising a negative electrode current collector; and a negative electrode active material layer comprising the negative electrode slurry according to any one of claims 7 to 12 or a cured or polymerized product thereof, provided on at least one surface of the negative electrode current collector.

14. The cathode of claim 13; membrane; and A secondary battery containing a cathode.

15. A battery module comprising the secondary battery of claim 14.

16. A battery pack comprising the secondary battery of claim 14.

17. A battery pack comprising the battery module of claim 15.