KR102535228B1 - Negative electrode and lithium secondary battery - Google Patents

Abstract

The present invention discloses a negative electrode and a lithium secondary battery capable of improving charge/discharge characteristics and high-rate cycle life characteristics of a battery by forming a metal fluoride layer to prevent loss of the SEI layer, thereby enabling improved battery performance and stable performance.

Description

Anode and lithium secondary battery {NEGATIVE ELECTRODE AND LITHIUM SECONDARY BATTERY}

The present invention relates to a negative electrode and a lithium secondary battery.

Lithium secondary batteries have a high voltage of 4 V, a wide utilization temperature of -20 to 50 degrees or more, a high power density of 1 kW/kg or more, and a high energy density of 100 Wh/kg or more, and research is actively being conducted worldwide. The lithium secondary battery is used in a variety of fields, including not only portable mobile power sources such as notebooks and mobile phones, but also HEV (Hybrid Electric Vehicle), PHEV (Plug in Hybrid Electric Vehicle), EV (Electric Vehicle), and energy storage system (ESS). The scope of application is expanding.

The negative electrode material of a lithium secondary battery accounts for about 15% of the material cost of a lithium ion battery, which is the third after positive electrode material and separator. .

In the charging process of the lithium secondary battery, unlike the theory of intercalation and desorption of lithium ions into the negative electrode active material, in practice, more lithium than the theoretical capacity is consumed. Accordingly, during discharging, some lithium ions are recovered. Accordingly, as the charge/discharge cycle continues, the desorption of lithium ions intensifies. The difference in capacity in the first charge and discharge reactions is called irreversible capacity loss. In commercialized lithium secondary batteries, lithium ions are supplied from the positive electrode and the negative electrode is manufactured without lithium, so there is no irreversible capacity loss in the initial charge and discharge. It is important to minimize

The initial irreversible capacity loss is related to the SEI layer (Solid Electrolyte Interface). The SEI layer formed at the beginning of charging prevents the reaction between lithium ions and the negative electrode or other materials during charging and discharging, and acts as an ion tunnel to pass only lithium ions, thereby suppressing further electrolyte decomposition reactions. This contributes to improving the cycle characteristics of lithium secondary batteries.

However, since a certain amount of lithium is necessarily consumed to form the SEI layer, the amount of reversible lithium is inevitably reduced compared to the originally designed amount. Lithium consumed in the formation of the SEI layer acts as an irreversible capacity, reducing the capacity of the battery.

Therefore, there is a need for a method for improving the initial irreversibility caused by the formation of the SEI layer.

For example, in order to reduce the consumption of lithium ions during initial charging and discharging and to increase the initial efficiency of the negative electrode, technologies such as vacuum depositing lithium on the negative electrode material or rolling a lithium foil on the negative electrode material have been proposed [B]. Patent Document 1]. However, such an attached lithium layer directly contacts and rapidly reacts with an anode active material such as a carbon material such as graphite, a Si-based material, or a Sn-based alloy material to generate LiCx, LiSix, LiMex, or the like. In the process of creating these compounds, a large amount of heat is generated at a very rapid rate, which eventually leads to thermal runaway of the battery.

Accordingly, a technique of changing the material of the active material layer or forming a separate buffer layer or protective film has been proposed.

Patent Document 1 proposes a method of increasing the thermal stability of a battery by forming a buffer layer containing an insulating material that does not react with lithium between SiOx-containing negative electrode mixture layers. However, the buffer layer caused a new problem of increased internal resistance of the battery due to its low conductivity.

Patent Document 2 suggests that the rate characteristics and heat generation degree of a battery can be improved by forming a buffer layer containing PVDF latex between the negative electrode mixture layer and the lithium layer. The buffer layer has an island shape or a strip shape. However, a sufficient level of thermal stability cannot be secured even with the introduction of such a buffer layer, and the problem of resistance increase due to the formation of the buffer layer still remains.

Accordingly, Patent Document 3 discloses a technique for preventing loss of the SEI layer by sequentially forming a polymer protective layer such as PVDF and a carbon-based protective layer on the metal lithium layer.

Patent Document 4 proposes a method of increasing battery efficiency by reducing initial irreversibility by forming 2 to 15 graphene layers on the negative electrode active material layer. This method is performed as a transfer method for a heat dissipation tape, and is not easy to apply in practice because the process is very complicated.

JP 2007-242590A (published on September 20, 2007) JP 6900970B (registered on 2021.06.21) KR 10-2018-0036600A (published on 2018.04.09) KR 10-2019-0074999A (published on 2019.06.28)

Cao, W. J et al., "The effect of lithium loadings on anode to the voltage drop during charge and discharge of Li-ion capacitors", Journal of Power Sources, Netherlands: N. p., 2015

In the lithium secondary battery, lithium ions are consumed by the SEI layer, resulting in an increase in irreversible capacity of the battery.

Therefore, based on the idea that the continuous consumption of lithium ions can be prevented by stabilizing the SEI layer, a protective film is formed on the active material layer, but after research on the material and composition of the protective film so as not to increase the resistance inside the conventional battery, arrived at the present invention.

The protective film of the present invention is a metal fluoride layer containing metal fluoride particles, and the metal fluoride is exposed to an electrolyte during charging and discharging to form LiF capable of stabilizing the SEI layer and a metal oxide having insulating properties through a chemical reaction. can As a result, the SEI layer was stabilized without increasing the internal resistance of the battery, effectively preventing an increase in the irreversible capacity of the battery, especially the initial irreversible capacity.

In addition, the protective film of the present invention can effectively prevent battery internal short circuits caused by lithium dendrites by acting by itself.

The active material layer expands and contracts in volume while occluding and releasing lithium ions; and a metal fluoride layer stacked on the upper surface of the active material layer.

At this time, at least a part of the metal fluoride layer contacts the electrolyte during charging to form a lithium fluoride film.

In addition, at least a part of the metal fluoride layer comes into contact with an electrolyte during charging to form a film containing lithium fluoride and a metal oxide.

The metal fluoride layer includes metal fluoride particles and a binder.

The metal fluoride particles are AlF ₃ , AgF, BaF ₂ , BiF ₃ , BiF ₅ , CdF ₂ , CaF ₂ , CeF ₃ , CeF ₅ , CsF ₂ , CrF ₃ , CoF ₂ , CoF ₃ , CuF ₂ , DyF ₃ , ErF ₃ , EuF ₃ , GaF ₃ , GdF ₃ , GeF ₂ , GeF ₄ , HfF ₄ , HoF 3, InF ₃ , FeF ₃ , LaF ₃ , PbF ₂ , PrF ₃ , LiF, MgF ₂ , MnF _{2 ,} MnF ₃ , Hg ₂ F ₂ , HgF ₂ , HgF ₄ , NaF, NbF ₄ , NdF ₃ , NiF ₂ , MoF ₆ , KF, RbF, SbF ₃ , SbF ₅ , ScF ₃ , SiF ₄ , SnF ₂ , SnF ₄ , SrF ₂ , TaF ₅ , TbF ₃ , TiF ₃ , TiF ₄ , TlF, TmF ₃ , VF ₃ , WF ₅ , YF ₃ , YbF ₃ , ZnF ₂ , and ZrF ₄ .

The binder is polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyacrylonitrile, polyacrylamide, carboxymethylcellulose, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyvinylpyridine, chlorosulfonated Polyethylene, polyester resin, acrylic resin, phenolic resin, epoxy resin, gum arabic, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, ethylene propylene Diene copolymer, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, hexafluoropropylene resin, chlorotrifluoroethylene resin, fluorovinyl resin, selected from the group consisting of perfluoroalkylvinyl ether resin more than one species

The metal fluoride layer is included in 0.1 part by weight to 50 parts by weight of a binder based on 100 parts by weight of metal fluoride particles.

The electrolyte solution is an organic liquid electrolyte or an inorganic liquid electrolyte.

The active material layer is at least one member selected from the group consisting of materials capable of reversibly intercalating/deintercalating lithium ions, lithium metals, alloys of lithium metals, materials capable of doping and undoping lithium, and transition metal oxides. am.

The material capable of doping and undoping lithium is at least one selected from the group consisting of a carbon-based active material, a silicon-based active material, and a Sn-based active material.

The silicon-based active material is Si, SiOx (0<x<2), Si—C complex, Si—Q alloy (Q is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a group 15 element, a group 16 element, It is an element selected from the group consisting of transition metals, rare earth elements, and combinations thereof, and is not Si).

A current collector is formed on the other surface of the active material layer on which the metal fluoride layer is not formed.

In addition, the present invention provides a secondary battery including the above-mentioned negative electrode, positive electrode, separator and electrolyte solution.

The negative electrode according to the present invention forms a metal fluoride layer on the active material layer, induces the formation of a stable SEI layer component, LiF, and forms a film containing a metal oxide to stabilize the SEI layer without increasing the internal resistance of the battery, An increase in the irreversible capacity of the battery, particularly the initial irreversible capacity, can be effectively prevented.

In addition, it is possible to improve the lifespan characteristics of the battery by effectively preventing a battery internal short circuit caused by lithium dendrites.

1 is a cross-sectional view showing an anode for a lithium secondary battery according to the present invention.
2 is XPS spectra of negative electrodes of Example 1 and Comparative Example 1 after charging.
3 is an XPS spectrum of the negative electrode of Example 1 before charging.
4 is an XPS spectrum of the negative electrode of Example 1 after charging.

The terminology used herein is only for referring to specific embodiments and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising" as used herein specifies particular characteristics, regions, integers, steps, operations, elements and/or components, and the presence or absence of other characteristics, regions, integers, steps, operations, elements and/or components. Additions are not excluded.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part or may be followed by another part therebetween. In contrast, when a part is said to be “directly on” another part, there is no intervening part between them.

In addition, unless otherwise specified, % means weight%, and 1ppm is 0.0001 weight%.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

In the present invention, the average particle diameter of the particles can be defined as the particle diameter at 50% of the particle diameter distribution of the particles. The average particle diameter (D50) of the particles according to an embodiment of the present invention can be measured using, for example, a laser diffraction method. The laser diffraction method is generally capable of measuring particle diameters of several millimeters in the submicron region, and can obtain results with high reproducibility and high resolution.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

1 is a cross-sectional view showing an anode 100 for a lithium secondary battery according to the present invention.

Referring to FIG. 1 , a negative electrode 100 for a lithium secondary battery includes a current collector 30 and an active material layer 20 stacked on an upper surface of the current collector 30 ; and a metal fluoride layer 10 stacked on the upper surface of the active material layer 20 .

The metal fluoride layer 10 includes metal fluoride particles, and the metal fluoride particles come into contact with an electrolyte during charging to form a film containing lithium fluoride (LiF) and a metal oxide as shown in the following reaction formula. That is, a part or all of the metal fluoride layer 10 has a structure in which a film containing lithium fluoride and a metal oxide is formed.

[Scheme 1]

MF + Li ⁺ -> LiF + MO

(In the above formula, M is a metal, and M-O means a metal oxide)

The lithium fluoride prevents loss of the SEI layer formed on the surface of the negative electrode active material layer 20, thereby enabling battery performance improvement and stable performance.

Specifically, the SEI layer can smoothly move lithium ions to the surface of the lithium electrode, prevent the reduction and decomposition reaction of the electrolyte by suppressing the permeation of organic solvent, reduce the irreversible capacity generated during charging and discharging, and improve the life characteristics of However, a problem arises in that the consumption of lithium ions in the SEI layer continuously increases. In the present invention, the SEI layer can be stably maintained without continuous consumption of lithium ions by forming lithium fluoride according to the above reaction formula.

In addition, the anode active material is pulverized by a large volume change during the desorption of lithium ions, and a new solid phase is formed when a new fracture surface occurs due to mechanical destruction. As this process is repeated, the electrolyte is consumed and the battery capacity decreases. will decrease drastically. The metal oxide generated in the metal fluoride layer 10 based on the above reaction is formed on the surface of the negative electrode active material layer 20 and has insulating properties. Due to such insulating performance, the active material in the negative active material layer 20 is not directly contacted with the electrolyte, so that mechanical destruction of the negative active material due to rapid lithium ion insertion can be prevented.

Also, by the above reaction, the metal fluoride layer 10 forms a film containing lithium fluoride (LiF) and a metal oxide, which means that the metal fluoride layer 10 itself functions as a protective film. As a result, it is possible to effectively prevent a short circuit inside the battery by suppressing dendrite lithium growth.

The metal fluoride layer 10 includes metal fluoride particles and a binder.

Metal fluoride particles are AlF ₃ , AgF, BaF ₂ , BiF ₃ , BiF ₅ , CdF ₂ , CaF ₂ , CeF ₃ , CeF ₅ , CsF ₂ , CrF ₃ , CoF ₂ , CoF ₃ , CuF ₂ , DyF ₃ , ErF ₃ , EuF ₃ , GaF ₃ , GdF _{3 ,} GeF ₂ , GeF _{4 , HfF 4 ,} HoF 3 , InF 3 , FeF ₃ , LaF ₃ , PbF ₂ , PrF ₃ , LiF, MgF ₂ , MnF _{2 ,} MnF ₃ , Hg ₂ F ₂ , HgF ₂ , HgF ₄ , NaF, NbF ₄ , NdF ₃ , NiF ₂ , MoF ₆ , KF, RbF, SbF ₃ , SbF ₅ , ScF ₃ , SiF ₄ , SnF ₂ , SnF ₄ , SrF ₂ , TaF ₅ , TbF ₃ , TiF ₃ , TiF ₄ , TlF, TmF ₃ , VF ₃ , WF ₅ , YF ₃ , YbF ₃ , ZnF ₂ , and ZrF ₄ At least one selected from the group consisting of is possible. Preferably, among them, AlF ₃ , TiF ₃ , MgF ₂ , BaF ₂ , AgF, CoF ₃ , NaF, AgF ₂ , CuF ₂ , FeF ₃ , MnF ₃ , ZnF ₂ , and ZrF ₄ are possible, and more preferably AlF ₃ , TiF ₃ , MgF ₂ , BaF ₂ , more preferably AlF ₃ are used.

The average particle diameter (D50) of the metal fluoride particles used in the present invention is 0.01 μm or more and 10.0 μm or less.

Specifically, 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, 1.0 μm or more, 2.0 μm or more, 3.0 μm or more, 4.0 μm or more, 5.0 μm or more, 6.0 μm or more, 7.0 μm or more, 8.0 μm or more, It is 9.0 μm or more. In addition, 10.0 μm or less, 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, 5.0 μm or less, 4.0 μm or less, 3.0 μm or less, 2.0 μm or less, 1.0 μm or less, 0.5 μm or less, 0.1 μm or less, 0.05 μm or less, It has a range of less than 0.02 μm.

If the average particle diameter of the metal fluoride particles is less than the above range, aggregation may occur during the manufacturing process, and conversely, if it exceeds the above range, a non-uniform surface may be formed, making it difficult to stably react with the electrolyte.

A binder is used to form the metal fluoride layer 10 .

Examples of the binder include polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyacrylonitrile, polyacrylamide, carboxymethylcellulose, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyvinylpyridine, chlorosulfonated Polyethylene, polyester resin, acrylic resin, phenolic resin, epoxy resin, gum arabic, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, ethylene propylene Diene copolymers, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymers, hexafluoropropylene resins, chlorotrifluoroethylene resins, fluorovinyl resins, perfluoroalkylvinyl ether resins, and combinations thereof One species selected from the group consisting of is possible. Preferably, polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyacrylonitrile, polyvinylidene fluoride, styrene-butadiene rubber, etc. may be used, and more preferably, polyacrylic acid may be used.

The binder has a weight average molecular weight of 150,000 g/mol or more, 170,000 g/mol or more, 200,000 g/mol or more, 250,000 g/mol or more, 300,000 g/mol or more, 350,000 g/mol or more, or 400,000 g/mol or more. g/mol or more, 450,000 g/mol or more, 500,000 g/mol or more, 550,000 g/mol or more, 600,000 g/mol or more, 650,000 g/mol or more, or 700,000 g/mol or more. In addition, 750,000 g / mol or less, 700,000 g / mol or less, 650,000 g / mol or less, 600,000 g / mol or less, 550,000 g / mol or less, 500,000 g / mol or less, 450,000 g / mol or less , 400,000 g/mol or less, 350,000 g/mol or less, 300,000 g/mol or less, 250,000 g/mol or less, 200,000 g/mol or less. Preferably, 150,000 g / mol or more, 170,000 g / mol or more, 200,000 g / mol or more, 250,000 g / mol or more, 300,000 g / mol or more, 350,000 g / mol or more, 400,000 g / mol or more mol or more, 450,000 g / mol or more, 500,000 g / mol or more, 750,000 g / mol or less, 700,000 g / mol or less, 650,000 g / mol or less, and 600,000 g / mol or less. More preferably, it has a range of 300,000 g / mol or more, 350,000 g / mol or more, 400,000 g / mol or more, 700,000 g / mol or less, 650,000 g / mol or less, 600,000 g / mol or less . The binder within this range not only forms the metal fluoride layer 10 in which metal fluoride particles are uniformly dispersed by exhibiting high dispersing power, but also has high adhesion to the active material layer 20 .

According to an embodiment of the present invention, the thickness of the metal fluoride layer 10 may be 0.1 μm or more and 20 μm or less.

Specifically, 0.1 μm or more, 0.15 μm or more, 0.2 μm or more, 0.5 μm or more, 1 μm or more, 1.2 μm or more, 1.5 μm or more, 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, 3.5 μm or more, 4.0 μm or more , 4.5 μm or more, 5.0 μm or more, 5.5 μm or more, 6.0 μm or more, 6.5 μm or more, 7.0 μm or more, 7.5 μm or more, 8.0 μm or more, 8.5 μm or more, 9.0 μm or more, 9.5 μm or more, 10.0 μm or more, 10.5 μm or more, 11.0 μm or more, 12.0 μm or more, 13.0 μm or more, 14.0 μm or more, 15.0 μm or more, 16.0 μm or more, 17 μm or more, 18 μm or more, or 19.0 μm or more. Further, 20.0 μm or less, 19.0 μm or less, 19.0 μm or less, 17.0 μm or less, 16.0 μm or less, 15.0 μm or less, 14.0 μm or less, 13.0 μm or less, 12.0 μm or less, 11.0 μm or less, 10.0 μm or less, 9.5 μm or less, 9.0 μm or less, 8.5 μm or less, 8.0 μm or less, 7.5 μm or less, 7.0 μm or less, 6.5 μm or less, 6.0 μm or less, 5.5 μm or less, 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, 2.0 μm or less, 1.5 μm or less, 1.2 μm or less, 1.0 μm or less, 0.5 μm or less, 0.2 μm or less, 0.15 μm or less. It preferably has a thickness of 1 μm to 20 μm, 5 μm to 15 μm, and 5 μm to 15 μm.

When the thickness of the metal fluoride layer 10 is less than the above range, sufficient LiF cannot be formed through reaction with the electrolyte, and when the thickness exceeds the above range, the mobility of lithium ions becomes an obstacle and resistance may increase.

According to one embodiment, the metal fluoride layer 10 of the present invention includes 0.1 parts by weight or more and 50 parts by weight or less of the binder based on 100 parts by weight of the metal fluoride particles. Specifically, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.5 parts by weight or more, 1.0 parts by weight or more, 5.0 parts by weight or more, 10.0 parts by weight or more, 15.0 parts by weight or more, 20.0 parts by weight or more, 25.0 parts by weight or more, 30.0 parts by weight or more. 35.0 parts by weight or more, 40.0 parts by weight or more, 45.0 parts by weight or more, and 47.0 parts by weight or more. In addition, 50 parts by weight or less, 49 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less Below, it is 5.0 parts by weight or less, 1.0 parts by weight or less, 0.5 parts by weight or less, and 0.3 parts by weight or less. Preferably 3 to 50 parts by weight, 5 to 40 parts by weight, 10 to 30 parts by weight, 20 parts by weight. If the content of the binder is less than the above range, it is difficult to uniformly disperse the metal fluoride particles in the metal fluoride layer 10, and conversely, when it is used above the above range, the thickness of the metal fluoride layer 10 increases, which hinders the movement of lithium ions. Battery resistance may increase.

The metal fluoride layer 10 is formed in a slurry state using a predetermined solvent, followed by wet coating and then drying.

The usable solvent may vary depending on the type of binder, for example, water, methanol, ethanol, propanol, isopropanol, acetone, dimethylformamide, dimethylacetamide, chloroform, dichloromethane, trichloroethylene, normalhexane, tetrahydro Aqueous solvents and organic solvents such as furan or a mixed solvent thereof may be used.

Considering the viscosity, coatability, and dispersibility of the slurry composition, the concentration of the solid content including the metal fluoride particles and the binder is 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more % or more, 40% or more, or 42% or more. In addition, it has a range of 45 wt% or less, 42 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, 25 wt% or less, 20 wt% or less, 17 wt% or less. Preferably, it has a range of 20% by weight or more, 23% by weight or more, 30% by weight or less, 27% by weight or less.

The coating process may be carried out by any method capable of uniformly coating the slurry composition on the active material layer 20 to form a thin film on the surface. For example, there are methods such as spin coating, doctor blade coating, dip coating, gravure coating, slit die coating, and screen coating. It is not limited. Subsequently, the metal fluoride layer 10 is prepared by volatilizing the solvent through drying.

An electrolyte in contact with the metal fluoride layer 10 may be a liquid electrolyte, which will be described in the following lithium secondary battery.

The active material layer 20 includes an active material whose volume expands and contracts while occluding and releasing lithium ions.

The active material is an anode active material, and includes, for example, a material capable of reversibly intercalating/deintercalating lithium ions, a lithium metal, an alloy of lithium metal, a material capable of doping and undoping lithium, or a transition metal oxide. do.

The alloy of lithium metal is from the group consisting of lithium and Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn. Alloys of selected metals may be used. The alloy of lithium metal is from the group consisting of lithium and Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn. Alloys of selected metals may be used.

A material capable of doping and undoping lithium may be, for example, a carbon-based active material.

As a representative example of the carbon-based active material, crystalline carbon, amorphous carbon, or both may be used together. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon ( hard carbon), mesophase pitch carbide, calcined coke, and the like.

Materials capable of doping and undoping lithium are, for example, Si, SiOx (0 <x <2), Si-C complex, Si-Q alloy (where Q is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, 15 and a silicon-based active material such as an element selected from the group consisting of group elements, group 16 elements, transition metals, rare earth elements, and combinations thereof, but not Si), and may be used by mixing at least one of these with SiO ₂ . may be The element Q includes Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, What is selected from the group consisting of Se, Te, Po, and combinations thereof may be used. In particular, a silicon-based active material including Si has an advantage of maintaining a high initial capacity and capacity even after repeated cycles.

Materials capable of doping and undoping lithium are, for example, Sn, SnO ₂ , S _n -R (wherein R is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a group 15 element, a group 16 element, a transition metal, a rare earth element) It is an element selected from the group consisting of elements and combinations thereof, and Sn-based active materials such as (not Sn) may be mentioned, and at least one of these and SiO ₂ may be mixed and used. The element R includes Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, What is selected from the group consisting of Se, Te, Po, and combinations thereof may be used.

The Si-C composite or Si-Q alloy is a form in which Si nanoparticles are coated on the surface of a carbon-based material or metal (Q), for example, graphite or metal (Q), or pores of graphite or metal (Q) It may be impregnated form.

Si-C composites, Si-Q alloys, etc. may have a core-shell type structure. For example, the core is any one of Si particles, Si, SiOx, Si-C composite, Si-Q alloy, Sn, SnO2, or Sn-R, and the shell is a core and other Si particles, Si, SiOx, Si-C It may be any one of composite, Si-Q alloy, Sn, SnO ₂ , or Sn-R. In addition, a metal of the same material as the current collector of the negative electrode may be used as the shell.

As the transition metal oxide, lithium titanium oxide such as Li ₄ Ti ₅ O ₁₂ may be used.

The active material layer 20 includes a binder and a conductive material in addition to an anode active material.

The binder is polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyacrylonitrile, polyacrylamide, carboxymethylcellulose, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyvinylpyridine, chlorosulfonated polyethylene, Polyester resin, acrylic resin, phenolic resin, epoxy resin, gum arabic, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, ethylene propylene diene air A group consisting of polymers, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymers, hexafluoropropylene resins, chlorotrifluoroethylene resins, fluorovinyl resins, perfluoroalkylvinyl ether resins, and combinations thereof One selected from is possible. Polyacrylic acid, polyvinyl alcohol, polyethylene glycol, etc. are preferably used, and polyacrylic acid may be used more preferably.

A conductive material is used to further improve the conductivity of the negative electrode active material. The conductive material is not particularly limited as long as it has conductivity without causing 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, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used. Specific examples of commercially available conductive materials include Chevron Chemical Company (Chevron Chemical Company), which is an acetylene black series, Denka Black (DenkaSingapore Private Limited), Gulf Oil Company products, etc.), Ketjenblack, EC series (Armak Company), Vulcan XC-72 (Cabot Company) and Super P (Timcal).

In addition, the active material layer 20 may further include a thickener. The thickener may be a cellulose-based compound, for example, one or more selected from the group consisting of carboxymethyl cellulose (CMC), hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose, and specifically, carboxymethyl cellulose (CMC)

In addition, the active material layer 20 may further include a dispersing agent, and the dispersing agent may be specifically an aqueous dispersing agent.

The dispersing agent is a cellulose compound, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetal, polyvinyl ether, polyvinyl sulfonic acid, polyvinyl chloride (PVC), polyvinylidene fluoride, chitosans, starch, amyl Rose (amylose), polyacrylamide, poly-N-isopropylacrylamide, poly-N,N-dimethylacrylamide, polyethyleneimine, polyoxyethylene, poly(2-methoxyethoxyethylene), poly(acrylamide) -co-diallyldimethylammonium chloride), acrylonitrile/butadiene/styrene (ABS) polymer, acrylonitrile/styrene/acrylic ester (ASA) polymer, acrylonitrile/styrene/acrylic ester (ASA) polymer and propylene carbonate , a styrene/acrylonitrile (SAN) copolymer, or a methyl methacrylate/acrylonitrile/butadiene/styrene (MABS) polymer, and the like, and any one or a mixture of two or more of these may be used.

In some cases, a filler or the like may be further included in the aqueous cathode slurry.

The filler may be used as a component that suppresses expansion of the negative electrode, and is not particularly limited as long as it does not cause chemical change in the secondary battery and is a fibrous material. For example, olefin-based polymers such as polyethylene and polypropylene; A fibrous material such as glass fiber or carbon fiber may be used.

A known wet or dry coating method may be used to form the active material layer 20 . For example, there are methods such as spin coating, doctor blade coating, dip coating, gravure coating, slit die coating, and screen coating, but are not limited thereto. no.

The current collector 30 is a negative electrode current collector, and is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, copper, gold, stainless steel, aluminum, nickel, titanium, burnt carbon, copper, Surface treatment of carbon, nickel, titanium, silver, etc. on the surface of stainless steel, aluminum-cadmium alloy, etc. may be used. In addition, fine irregularities may be formed on the surface to enhance the bonding strength of the negative active material, and may be used in various forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics. At this time, the negative current collector generally has a thickness of 3 μm to 500 μm.

lithium secondary battery

In addition, the present invention provides a lithium secondary battery including a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte.

At this time, the negative electrode as described above may be used as the negative electrode.

The lithium secondary battery of the present invention can be manufactured by injecting the non-aqueous electrolyte of the present invention into an electrode structure composed of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. At this time, as the positive electrode, the negative electrode, and the separator forming the electrode structure, those conventionally used in manufacturing a lithium secondary battery may all be used.

In this case, the positive electrode may be prepared by coating a positive electrode active material slurry including a positive electrode active material and optionally a binder, a conductive material, and a solvent on a positive electrode current collector, followed by drying and rolling.

The cathode current collector is not particularly limited as long as it does not cause chemical change in the battery and has conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or carbon on the surface of aluminum or stainless steel. , those surface-treated with nickel, titanium, silver, etc. may be used.

The cathode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium composite metal oxide containing lithium and at least one metal such as cobalt, manganese, nickel, or aluminum. there is. More specifically, the lithium composite metal oxide is lithium-manganese-based oxide (eg, LiMnO ₂ , LiMn ₂ O ₄ , etc.), lithium-cobalt-based oxide (eg, LiCoO _{2 ,} etc.), lithium-nickel-based oxide (eg, LiNiO _{2 ,} etc.), lithium-nickel-manganese-based oxide (eg, LiNi _1-Y MnYO ₂ (where 0<Y<1), LiMn _2-z Ni _z O ₄ (where , 0<Z<2), etc.), lithium-nickel-cobalt-based oxide (eg, LiNi _1-Y1 Co _Y1 O ₂ (here, 0<Y1<1), etc.), lithium-manganese-cobalt-based oxide (eg, LiCo _1-Y2 Mn _Y2 O ₂ (where 0<Y2<1), LiMn _2-z 1Co _z1 O ₄ (where 0<Z1<2), etc.), lithium-nickel-manganese -Cobalt-based oxide (eg, Li(Ni _p Co _q Mn _r1 ) O ₂ (here, 0<p<1, 0<q<1, 0<r1<1, p+q+r1=1) or Li(Ni _p1 Co _q1 Mn _r2 )O ₄ (where 0<p1<2, 0<q1<2, 0<r2<2, p1+q1+r2=2), etc.), or lithium-nickel- Cobalt-transition metal (M) oxides (eg, Li(Ni _p2 Co _q2 Mn _r3 MS ₂ ) O ₂ where M is the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo is selected from, and p2, q2, r3 and s2 are atomic fractions of independent elements, respectively, 0 <p2 <1, 0 <q2 <1, 0 <r3 <1, 0 <s2 <1, p2 + q2 + r3 +s2=1) and the like), and the like, and any one or two or more of these compounds may be included. Among them, in that the capacity characteristics and stability of the battery can be improved, the lithium composite metal oxide is LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , lithium nickel manganese cobalt oxide (eg, Li(Ni _0.6 Mn _0.2 Co _0.2 )O ₂ , Li(Ni _0.5 Mn _0.3 Co _0.2 )O ₂ , or Li(Ni _0.8 Mn _0.1 Co _0.1 )O ₂ , etc.), or lithium nickel cobalt aluminum oxide (eg, Li(Ni _0.8 Co _0.15 Al _0.05 )O ₂ etc.), etc., and considering the remarkable effect of improvement according to the type and content ratio control of the constituent elements forming the lithium composite metal oxide, the lithium composite metal oxide is Li(Ni _0.6 Mn _0.2 Co _0.2 )O ₂ , Li (Ni _0.5 Mn _0.3 Co _0.2 )O ₂ , Li(Ni _0.7 Mn _0.15 Co _0.15 )O ₂ or Li(Ni _0.8 Mn _0.1 Co _0.1 )O ₂ , etc., any one of these or a mixture of two or more may be used. .

The positive electrode active material may be included in an amount of 80% to 99% by weight based on the total weight of each positive electrode mixture.

The binder is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector, and is typically added in an amount of 1% to 30% by weight based on the total weight of the positive electrode mixture. 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-butadiene rubber, fluororubber, various copolymers, and the like.

The conductive material is typically added in an amount of 1 wt% to 30 wt% based on the total weight of the positive electrode mixture.

Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used. Specific examples of commercially available conductive materials include Chevron Chemical Company, which is an acetylene black series, Denka Singapore Private Limited, Gulf Oil Company products, etc.), Ketjenblack, EC series (Armak Company), Vulcan XC-72 (Cabot Company) and Super P (Timcal).

The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desired viscosity when the cathode active material and optionally a binder and a conductive material are included. For example, the solid content including the positive electrode active material and, optionally, the binder and the conductive material may be included such that the concentration is 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%.

In the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ion movement, and any separator used as a separator in a lithium secondary battery can be used without particular limitation. It is preferable to have an excellent ability to absorb the electrolyte while being resistant. Specifically, a porous polymer film, for example, a porous polymer film made of polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer, or these A laminated structure of two or more layers of may be used. In addition, conventional porous non-woven fabrics, for example, non-woven fabrics made of high-melting glass fibers, polyethylene terephthalate fibers, and the like may be used. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may be selectively used in a single layer or multilayer structure.

In addition, the electrolyte used in the present invention may include an organic liquid electrolyte or an inorganic liquid electrolyte usable in manufacturing a lithium secondary battery, but is not limited thereto.

Specifically, the electrolyte may include an organic solvent and a lithium salt.

The organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, examples of the organic solvent include ester-based solvents such as methyl acetate, ethyl acetate, gamma-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a C2 to C20 straight-chain, branched or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; Alternatively, sulfolane or the like may be used. Among them, carbonate-based solvents are preferred, and cyclic carbonates (eg, ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high permittivity that can increase the charge and discharge performance of batteries, and low-viscosity linear carbonate-based compounds ( For example, a mixture of ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate) is more preferable. In this case, when the cyclic carbonate and the chain carbonate are mixed in a volume ratio of about 1:1 to about 1:9, the performance of the electrolyte may be excellent.

The lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt is LiPF6, LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlO 4 , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN( _{C 2 F 5} SO ₃ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ , LiCl, LiI, or LiB(C ₂ O ₄ ) ₂ may be used. The concentration of the lithium salt is preferably used within the range of 0.1 to 2.0M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so excellent electrolyte performance can be exhibited, and lithium ions can move effectively.

In addition to the above electrolyte components, the electrolyte may include, for example, haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, and triglycerides for the purpose of improving battery life characteristics, suppressing battery capacity decrease, and improving battery discharge capacity. Ethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imida One or more additives such as zolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol or aluminum trichloride may be further included. In this case, the additive may be included in an amount of 0.1% to 5% by weight based on the total weight of the electrolyte.

As described above, since the lithium secondary battery according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, portable devices such as mobile phones, notebook computers, digital cameras, and hybrid electric vehicles (HEVs) ), etc., and is useful in the field of electric vehicles, and in particular, it can be preferably used as a component battery of a medium or large battery module. Accordingly, the present invention also provides a medium or large-sized battery module including the above secondary battery as a unit battery.

Such medium- or large-sized battery modules may be preferably applied to power sources requiring high output and large capacity, such as electric vehicles, hybrid electric vehicles, and power storage devices.

[Example]

Examples and comparative examples of the present invention are described below. However, the following examples describe a preferred embodiment of the present invention, and the present invention is not limited by the following examples.

[Slurry composition for cathode preparation and preparation of cathode]

An anode active material, carbon black (product name: Super C65, manufacturer: Timcal) as a conductive material, and a binder were added to distilled water as a solvent for forming a cathode slurry in a weight ratio of 80:10:10 to prepare a slurry composition.

As a negative electrode current collector, the negative electrode slurry was coated on one surface of a copper current collector (thickness: 8 μm), rolled, and dried in a vacuum oven at 130 ° C. for 10 hours to form a negative active material layer.

To form a metal fluoride layer, 100 parts by weight of AlF ₃ (size: 0.1 μm) and 20 parts by weight of polyacrylic acid (MW 450,000 g/mol) were added to distilled water to prepare a slurry composition. After coating the slurry composition on the negative electrode active material layer, it was rolled and dried in a vacuum oven at 130° C. for 10 hours to form a metal fluoride layer.

[Lithium secondary battery manufacturing: half cell]

Li metal was used as a counter electrode, and after interposing a polyolefin separator between each negative electrode and Li metal prepared above, ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 30:70 Coin-type half-cells were prepared by injecting an electrolyte in which 0.5 wt% of vinylene carbonate and 1M LiPF ₆ were dissolved in the mixed solvent, respectively.

[Test Methods]

(1) 100 cycle life retention rate (%) : The capacity retention rate at 50 cycles is defined by Equation 1 below.

<Equation 1>

Capacity retention rate (%) = Discharge capacity at 100 cycles / Discharge capacity at 1 cycle X 100

(2) Charge/discharge efficiency (%) : The charge/discharge efficiency in a corresponding cycle is defined by Equation 2.

<Equation 2>

Charge/discharge efficiency (%) = Discharge capacity in a given cycle / Charge capacity in a given cycle X 100

Test Example 1

After charging and discharging the negative electrode on which the metal fluoride layer having the composition of Example 1 and Comparative Example 1 (bare) was formed, X-ray Photoelectron Spectroscopy (XPS) confirmed that the metal fluoride layer formed LiF and Al ₂ O ₃ . confirmed through

2 is XPS spectra of negative electrodes of Example 1 and Comparative Example 1 after charging. Referring to FIG. 2, when only Si of Comparative Example 1 was present, the LiF peak was confirmed. In addition, in the case of Example 1, it was confirmed that the peak of LiF was stronger than the peak of Comparative Example 1, which seems to be due to AlF ₃ , which is a metal fluoride layer.

3 is an XPS spectrum of the negative electrode of Example 1 before charging, and a strong Al peak was confirmed. 4 is an XPS spectrum of the negative electrode of Example 1 after charging, confirming that Al—O bonds exist together with AlF ₃ in the negative electrode.

Test Example 2

In order to measure the physical properties of the battery according to the coating method, the results are shown after performing the composition in Table 1 below.

division cathode active material Fluoride Metal Particles
100 cycle life retention rate 100 times charge/discharge efficiency (C.E) Example 1 Si AlF ₃ 85 99.98 Example 2 Si TiF ₃ 82 99.98 Example 3 Si MgF ₃ 78 99.97 Example 4 Si _BaF3 75 99.97 Example 5 SiO AlF ₃ 91 99.99 Example 6 Si/C AlF ₃ 90 99.99 Comparative Example 1 Si - 55 99.6 Comparative Example 2 SiO - 82 99.98 Comparative Example 3 Si/C - 81 99.98

Referring to the above table, in the case of using the negative electrode having a metal fluoride layer having metal fluoride particles as in Examples 1 to 6, excellent results were obtained in terms of battery characteristics compared to the cells of Comparative Examples 1 to 3 without a metal fluoride layer.

Test Example 3

A negative electrode was prepared by varying the coating thickness of the metal fluoride layer and the type and content of the binder, and the battery properties were measured and are shown in Table 2 below. At this time, the metal fluoride layer was used based on Example 1.

division metal fluoride layer thickness Binder (content)
Initial Efficiency (%) 100 cycle life retention rate Example 1 10 µm PAA (20 parts by weight) 80 85 Example 7 20 µm PAA (20 parts by weight) 75 88 Example 8 30 µm PAA (20 parts by weight) 70 90 Example 9 10 µm PVA (20 parts by weight) 78 82 Example 10 10 µm PVDF (20 parts by weight) 77 80 Example 11 10 µm PAA (10 parts by weight) 78 81 Example 12 10 µm PAA (30 parts by weight) 77 82 Example 13 10 µm PAA (40 parts by weight) 75 78

Looking at the above table, as the thickness of the metal fluoride layer increases, the life retention rate improves. The initial efficiency tended to decrease. In addition, when changing the type of binder, PAA was most excellent. In addition, the best effect was confirmed when the content of the binder was within 20 parts by weight.

What has been described above is only one embodiment for carrying out a secondary battery including the negative electrode active material, its manufacturing method, and negative electrode active material according to the present invention, and the present invention is not limited to the above-described embodiment, and the following claims As claimed in the scope, it is included in the technical spirit of the present invention to the extent that various changes can be made by anyone having ordinary knowledge in the field to which the present invention belongs without departing from the gist of the present invention.

10: metal fluoride layer
20: active material layer
30: entire collector
100: cathode

Claims (14)

an active material layer whose volume expands and contracts while occluding and releasing lithium ions; and
A negative electrode including a metal fluoride layer stacked on the upper surface of the active material layer,
At least a part of the metal fluoride layer comes into contact with an electrolyte during charging to form a film including a lithium fluoride film and a metal oxide,
The electrolyte solution is a liquid electrolyte, and the thickness of the metal fluoride layer is 0.1 μm or more and 20 μm or less,
The metal fluoride layer is prepared in a slurry state containing 0.1 part by weight to 50 parts by weight of a binder based on 100 parts by weight of metal fluoride particles, and then prepared by wet coating on the upper surface of the active material layer and then drying. delete delete According to claim 1,
The metal fluoride particles are AlF ₃ , AgF, BaF ₂ , BiF ₃ , BiF ₅ , CdF ₂ , CaF ₂ , CeF ₃ , CeF ₅ , CsF ₂ , CrF ₃ , CoF ₂ , CoF ₃ , CuF ₂ , DyF ₃ , ErF ₃ , EuF ₃ , GaF ₃ , GdF ₃ , GeF ₂ , GeF ₄ , HfF ₄ , HoF 3, InF ₃ , FeF ₃ , LaF ₃ , PbF ₂ , PrF _{3 ,} LiF, MgF ₂ , MnF ₂ , MnF ₃ , Hg ₂ F ₂ , HgF ₂ , HgF ₄ , NaF, NbF ₄ , NdF ₃ , NiF ₂ , MoF ₆ , KF, RbF, SbF ₃ , SbF ₅ , ScF ₃ , SiF ₄ , SnF ₂ , SnF ₄ , SrF ₂ , TaF ₅ , TbF ₃ , TiF ₃ , TiF ₄ , TlF, TmF ₃ , VF ₃ , WF ₅ , YF ₃ , YbF ₃ , ZnF ₂ , and ZrF ₄ At least one member selected from the group consisting of, a negative electrode. According to claim 1,
The metal fluoride particles are AlF ₃ , TiF ₃ , MgF ₂ , BaF ₂ , AgF, CoF ₃ , NaF, AgF ₂ , CuF ₂ , FeF ₃ , MnF ₃ , ZnF ₂ , and ZrF ₄ At least one member selected from the group consisting of , cathode. According to claim 1,
The binder is polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyacrylonitrile, polyacrylamide, carboxymethylcellulose, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyvinylpyridine, chlorosulfonated polyethylene , polyester resin, acrylic resin, phenol resin, epoxy resin, gum arabic, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluoro rubber, ethylene propylene diene 1 selected from the group consisting of a copolymer, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, hexafluoropropylene resin, chlorotrifluoroethylene resin, fluorovinyl resin, and perfluoroalkylvinyl ether resin More than species, the cathode. According to claim 1,
The negative electrode, wherein the binder is at least one selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyacrylonitrile, polyvinylidene fluoride, and styrene-butadiene rubber. delete delete According to claim 1,
The active material layer is at least one selected from the group consisting of a material capable of reversibly intercalating/deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and undoping lithium, and a transition metal oxide. , cathode. According to claim 10,
The negative electrode, wherein the material capable of doping and undoping lithium is at least one selected from the group consisting of a carbon-based active material, a silicon-based active material, and a Sn-based active material. According to claim 11,
The silicon-based active material is Si, SiOx (0<x<2), Si—C complex, Si—Q alloy (Q is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a group 15 element, a group 16 element, An element selected from the group consisting of transition metals, rare earth elements, and combinations thereof, but not Si), which is any one or more of the negative electrode. According to claim 1,
A negative electrode, wherein a current collector is formed on the other surface of the active material layer on which the metal fluoride layer is not formed. A secondary battery including a negative electrode, a positive electrode, a separator and an electrolyte,
The negative electrode is a secondary battery comprising the negative electrode according to claim 1.

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