Negative electrode active material and rechargeable lithium battery including same

Abstract

The invention relates to a negative electrode active material and a rechargeable lithium battery including the same. The negative electrode active material has a span value of 1.1 to 1.6 according to the following Equation 1, and includes: secondary particles each constituted by aggregated primary particles, each of the primary particles including silicon nanoparticles and a metal coating layer surrounding the silicon nanoparticles and containing a metal-based material; and an amorphous carbon coating layer surrounding the surfaces of the primary particles and the secondary particles. [Equation 1] Span = (D90-D10) / D50 (In Equation 1, D10 represents a particle size corresponding to a 10% cumulative volume in the particle size distribution, D50 represents a particle size corresponding to a 50% cumulative volume in the particle size distribution, and D90 represents a particle size corresponding to a 90% cumulative volume in the particle size distribution).

Description

Technical Field

[0001] The implementation involves a negative electrode active material and a rechargeable lithium battery including therein. Background Technology

[0002] The recent rapid increase in battery-powered electronic devices such as mobile phones, laptops, and electric vehicles has led to a surprising increase in demand for rechargeable batteries with relatively high capacity and light weight.

[0003] As a result, there is a need to develop batteries with high energy density, which in turn requires high-capacity negative electrode active materials.

[0004] We have tried using Si negative electrode active material as a high-capacity negative electrode active material. Summary of the Invention

[0005] Technical issues

[0006] One implementation provides a negative electrode active material that exhibits excellent electrical conductivity.

[0007] Another embodiment provides a rechargeable lithium battery including the negative electrode active material.

[0008] Technical solution

[0009] One embodiment relates to a negative electrode active material comprising: a span of about 1.1 to about 1.6 as defined by Equation 1; secondary particles wherein the primary particles are agglomerated (aggregated), the primary particles comprising silicon nanoparticles and a metal coating (coating) comprising a metallic material surrounding the respective surfaces of the silicon nanoparticles; and an amorphous carbon coating surrounding the surfaces of the primary particles and the secondary particles.

[0010] [Equation 1]

[0011] Span = (D90 - D10) / D50

[0012] (Where, D10 represents the diameter of a particle with a cumulative volume of 10% in the particle size distribution, D50 represents the diameter of a particle with a cumulative volume of 50% in the particle size distribution, and D90 represents the diameter of a particle with a cumulative volume of 90% in the particle size distribution.)

[0013] According to another embodiment, a rechargeable lithium battery includes: a negative electrode comprising the negative electrode active material; a positive electrode; and an electrolyte.

[0014] Beneficial effects

[0015] The negative electrode active material according to one embodiment can exhibit excellent conductivity. Attached Figure Description

[0016] Figure 1 A cross-sectional view of a rechargeable lithium battery according to some embodiments is shown schematically. Detailed Implementation

[0017] In the following sections, embodiments of the present disclosure will be described in detail. However, these embodiments are presented by way of example, and the present disclosure is not limited thereto, and is defined by the scope of the claims described below.

[0018] The terminology used in this specification is for illustrative purposes and is not intended to limit the invention. Unless the context clearly specifies otherwise, singular expressions include plural expressions. The term "combinations thereof" may include mixtures, laminates, complexes, copolymers, alloys, blends, reaction products, etc., of the constituent elements.

[0019] The terms “comprising,” “including,” or “having” are intended to specify the presence of the characteristics, quantities, steps, components, or combinations thereof performed, but it should be understood that the possibility of the presence or addition of one or more other characteristics, quantities, steps, components, or combinations thereof is not excluded in advance.

[0020] The accompanying drawings show the thickness magnified to clearly show the individual layers and regions, and the same reference numerals are used for similar parts throughout the specification. If an element, such as a layer, film, region, plate, etc., is referred to as being "on" or "above" another element, it may include cases where it is "directly on" the other element, and may include cases where another element exists in between. Conversely, when an element is referred to as being "directly on" another element, there are no intermediate elements.

[0021] In some embodiments, as used herein, "layer" includes shapes that are formed entirely on the entire surface or on a portion of the surface when viewed from a plan view.

[0022] As used in this article, "or" will not be interpreted in an exclusive sense; for example, "A or B" can be interpreted as including A, B, A+B, etc.

[0023] In this disclosure, unless otherwise defined, particle size or particle diameter (particle diameter or size) may refer to the average particle size. The average particle size represents the average diameter of particles in the cumulative volume of the particle size distribution comprising the particles in the negative electrode active material. The average particle size can be measured by suitable methods, such as by a particle size analyzer or by transmission electron microscopy (TEM) or scanning electron microscopy (SEM) images. In some embodiments, data analysis can be performed using a dynamic light scattering measurement device, and the number of particles can be counted for each particle size range, thereby allowing the average particle size value to be readily obtained by calculation.

[0024] According to some embodiments, the negative electrode active material may have: a span of about 1.1 to about 1.6 as defined by Equation 1; secondary particles wherein the primary particles may agglomerate, the primary particles may include silicon nanoparticles and a metal coating layer including a metallic material surrounding the respective surfaces of the silicon nanoparticles; and an amorphous carbon coating layer surrounding the surfaces of the primary particles and the secondary particles.

[0025] [Equation 1]

[0026] Span = (D90 - D10) / D50

[0027] In Equation 1, D10 can represent the diameter of a particle with a cumulative volume of 10% in the particle size distribution, D50 can represent the diameter of a particle with a cumulative volume of 50% in the particle size distribution, and D90 can represent the diameter of a particle with a cumulative volume of 90% in the particle size distribution.

[0028] In practice, the span, as defined by Equation 1, can be, for example, about 1.1 to about 1.55 or about 1.1 to about 1.5.

[0029] The range of negative electrode active materials within the above range indicates that fine powder negative electrode active materials may be substantially excluded. In practice, fine powders having a size of about 1 μm or smaller and typically having an indistinct shape may be rarely included, and therefore the negative electrode active material may have a low specific surface area, thereby reducing side reactions with the electrolyte and improving cycle life.

[0030] According to one embodiment, the negative electrode active material may have a low specific surface area, for example, a low BET specific surface area, and the specific surface area may be about 0.5 m². 2 / g to approximately 2 m 2 / g, approximately 0.8 m 2 / g to approximately 2 m 2 / g or approximately 0.8 m 2 / g to approximately 1.5m 2 / g. The specific surface area within the above range can be compared to the specific surface area of ​​the silicon-carbon composite negative electrode active material (which can be approximately 3 m²). 2 / g) low value.

[0031] According to one embodiment, the negative electrode active material may include primary particles and secondary particles in which the primary particles can agglomerate, and an amorphous carbon coating layer surrounding the surface of the secondary particles.

[0032] In practice, the primary particles may include silicon nanoparticles and a metal coating layer surrounding the silicon nanoparticles on the surface of the silicon nanoparticles, and the metal coating layer may include a metallic material. Alternatively, the amorphous carbon coating layer may include a metallic material.

[0033] In practice, the metal included in the metal cladding layer can be the same as the metal included in the amorphous carbon cladding layer.

[0034] In a negative electrode active material according to one embodiment, the primary particles may be silicon nanoparticles surrounded by a metal coating layer, and may include a coating layer comprising a layer of metallic material that is substantially continuously covering the surface of the silicon nanoparticles. In this embodiment, the surface of the silicon nanoparticles may be completely covered by the metal coating layer, thereby preventing the surface of the silicon nanoparticles from being exposed. In this embodiment, placing the metal coating layer in the form of a layer indicates that the metal coating layer, which may be disposed along the surface of the silicon nanoparticles at a predetermined thickness, may be disposed in the region in contact with the silicon nanoparticles. This can improve the internal conductivity of the negative electrode active material, thereby improving the uniformity of charging and discharging, and improving silicon utilization through the improvement of electrical conductivity (conductivity) caused by the coating layer and by reducing side reactions. In this embodiment, if the metal coating layer, which is discontinuously present on the surface of the silicon nanoparticles, unevenly covers the surface of the silicon nanoparticles in the form of an island-shaped or point-contact arrangement, the effect from the formation of the metal coating layer may be insignificant. In practice, the island-shaped form indicates that the metal cladding layer is located only at specific locations on the surface of the silicon nanoparticles, rather than continuously on the surface of the silicon nanoparticles.

[0035] The thickness of the metal coating can be from about 1 nm to about 30 nm, from about 1 nm to about 20 nm, or from about 5 nm to about 20 nm. Keeping the thickness of the metal coating within these ranges helps ensure that a greater improvement in electrical conductivity can be achieved through the metal coating, and that the interior of the active material can be used more uniformly if the battery is being operated.

[0036] In the negative electrode active material, the amorphous carbon coating layer can surround or cover the surfaces of the secondary and primary particles, and it can be between the primary particles and on the surface of the secondary particles.

[0037] In practice, the amorphous carbon coating may include metallic materials.

[0038] The metallic material included in the amorphous carbon coating can be present in the amorphous carbon coating by including some of the following metallic materials during the preparation of the negative electrode active material: said metallic materials can be prepared during the preparation of a metal coating to be located on the surface of silicon nanoparticles. Therefore, the metal included in the amorphous carbon coating can be the same as the metal in the metal coating.

[0039] In practice, the metallic material included in the metal cladding layer and the amorphous carbon cladding layer may be a metal or a metal compound.

[0040] Metal compounds may include metal oxides, metal nitrides, or combinations thereof.

[0041] The metal may be any metal capable of alloying with lithium and may include alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, or combinations thereof. In embodiments, the metal may include Ag, 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, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or combinations thereof. In embodiments, the metal may be Ag.

[0042] Since the coating, including the metal, can be distributed on the surface of both primary and secondary particles, that is, inside and outside the active material, the conductivity of the active material can be enhanced both inside and outside.

[0043] Based on a total of 100% by weight of negative electrode active material, the amount of metal material can be from about 0.01% by weight to about 20% by weight, from about 0.05% by weight to about 15% by weight, or from about 0.01% by weight to about 10% by weight. In practice, the amount of metal material can be the total amount of metal material included in the negative electrode active material, and there is no need to limit the amounts included in the metal coating layer or the amorphous carbon coating layer. Maintaining the amount of metal material within the above range helps ensure that the conductivity of the active material can be further improved, allowing for more uniform utilization of the interior of the active material.

[0044] In the negative electrode active material according to one embodiment, in the measurement of X-ray diffraction intensity, the diffraction peak intensity (I) originating from the metal (111) detected at 2θ = about 37.5° to about 40.0° 金属(111) The intensity of the diffraction peak originating from Si(111) detected at 2θ = approximately 27.5° to approximately 29.5° is (I) Si(111) Peak intensity ratio (I) 金属(111) / I Si(111) The peak intensity ratio (I) can be from approximately 0.05 to approximately 0.5. 金属(111) / I Si(111) The peak intensity ratio can be from about 0.2 to about 0.4 or from about 0.1 to about 0.4. The peak intensity ratio can vary depending on the type of metal, and if the metal is Ag, the peak intensity ratio can be a value that satisfies. In practice, the diffraction peak intensity ratio can be I. Ag(111) / I Si(111) .

[0045] Peak intensity ratio (I) within the range Ag(111) / I Si(111) This indicates that Si and metals (e.g., Ag) exist in the structure of the negative electrode active material at a predetermined ratio, which indicates an increase in the conductivity of the negative electrode active material. The increased conductivity of the active material leads to the majority of silicon nanoparticles participating in the charging and discharging reactions, resulting in uniform charging and discharging, thereby achieving high capacity and long cycle life.

[0046] If the amount of metallic material increases, the intensity of the diffraction peaks (I) originating from the metal, such as Ag, will increase. Ag(111) This can increase the peak intensity ratio (I) Ag(111) / I Si(111) The peak intensity ratio (I) increases within the range described. Ag(111) / I Si(111) This indicates that Ag is appropriately included.

[0047] In one implementation, peak intensity can be either the height of the peak or the integral area of ​​the peak, and in another implementation, it can be the integral area of ​​the peak.

[0048] X-ray diffraction intensity can be measured using CuKα rays as the target ray, and the measurement conditions can be: 2θ = approximately 20° to approximately 80°, a scan rate of 0.044 to 0.089 (° / s), and a step size of 0.013 to 0.039 (° / step). Peak intensity ratio (I 金属(111) / I Si(111) For example, I Ag(111) / I Si(111) The ratio that can represent the peak intensity, such as a relative value, and therefore, the peak intensity (I) of the (111) plane of the metal. 金属(111) The peak intensity (I) of the (111) plane of Si Si(111) The absolute value of ) can vary depending on the X-ray diffraction analysis measurement conditions, but note the following as important: peak intensity ratio (I 金属(111) / I Si(111) The essence itself remains largely unchanged.

[0049] In one embodiment, the particle size of the metallic material included in the amorphous carbon coating layer may be from about 1 nm to about 30 nm, and in another embodiment, it may be from about 1 nm to about 20 nm or from about 5 nm to about 20 nm. Keeping the particle size of the metallic material within these ranges helps ensure more uniform use of the interior of the active material during battery operation.

[0050] In one embodiment, the silicon nanoparticles may have a particle size of about 10 nm to about 1,000 nm, and in another embodiment, they may have a particle size of about 10 nm to about 200 nm or about 20 nm to about 150 nm. Maintaining the average particle size of the silicon nanoparticles within these ranges helps to ensure that extreme volume expansion during charging and discharging is suppressed and that breakage of conductive paths due to particle fragmentation is prevented.

[0051] In the amorphous carbon coating, the amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbides, sintered coke, or a combination thereof. The thickness of the amorphous carbon coating can be about 1 nm to about 2 μm, about 1 nm to about 500 nm, about 10 nm to about 300 nm, or about 20 nm to about 200 nm. Maintaining the thickness of the amorphous carbon coating within these ranges helps to better ensure that silicon volume expansion is suppressed during charging and discharging.

[0052] In the negative electrode active material, based on a total of 100 wt% of the negative electrode active material, the amount of silicon nanoparticles may be from about 44 wt% to about 65 wt% or from about 52 wt% to about 62 wt%. Based on a total of 100 wt% of the negative electrode active material, the amount of amorphous carbon coating layer may be from about 34 wt% to about 46 wt% or from about 36 wt% to about 41 wt%.

[0053] The negative electrode active material according to some embodiments can be prepared by the following procedure.

[0054] Micron-sized silicon particles, a metallic precursor, and a dispersant can be mixed in a solvent. Mixing can be carried out by, but is not limited to, ball milling using zirconia balls, and can be performed by any technique that can pulverize the silicon particles. Through mixing, pulverization can be performed to prepare nano-sized primary silicon particles. The solvent may include organic solvents such as ethanol, methanol, propanol, etc. The particle size of the primary silicon particles can be from about 1 nm to about 1000 nm, from about 10 nm to about 100 nm, or from about 20 nm to about 150 nm. The dispersant may be stearic acid, boron nitride (BN), MgS, polyvinylpyrrolidone (PVP), or combinations thereof.

[0055] The mixing ratio of silicon particles and metal precursors can be adjusted to a silicon-to-metal ratio of about 100:1 to about 100:30 or about 100:1 to about 100:25 by weight. During mixing, the amount of dispersant can be suitable for good dispersion of the silicon particles and metal precursors in the solvent, and can be about 100:1 to about 100:30 or about 100:10 to about 100:30 by weight.

[0056] The metallic precursor can be a metal, a metal nitride, a metal carbide, a metal sulfide, a metal halide, or a combination thereof. The halide can be a chloride or a fluoride. As mentioned above, the metal can be a metal capable of alloying with lithium. The resulting mixture can be dried. The drying process can be carried out by spray drying. Because the drying process can be carried out by spray drying, a dried product with a more uniform particle size and spherical shape can be prepared, and secondary particles in which the primary particles agglomerate can be prepared. This allows the metal or metal oxide to be located on the surface of the silicon primary particles. The silicon primary particles and the metallic precursor can agglomerate together to prepare agglomerated secondary particles. Some of the metallic precursor between the primary particles can be on the surface of the secondary particles. If the dried product can be particles with a uniform particle size and spherical shape, the subsequently prepared amorphous carbon layer can be formed more uniformly across the entire surface.

[0057] In the process, some of the metallic materials may also include amorphous carbon that can be subsequently formed. An amorphous carbon layer can be formed on the dried product. The formation of the amorphous carbon layer can be carried out by vapor-phase coating (coating) with an amorphous carbon precursor gas, or by mixing the dried product with the amorphous carbon precursor and carbonizing it.

[0058] The amorphous carbon precursor gas can be methane (CH4), ethylene (C2H4), acetylene (C2H2), propane (C3H8), propylene (C3H6), or a combination thereof, and the amorphous carbon precursor can be petroleum coke, coal coke, petroleum pitch, coal pitch, raw coke, or a combination thereof.

[0059] Carbonization can be carried out at approximately 600°C to approximately 1,000°C. During carbonization, the dispersant can be removed. Carbonization can be carried out under a N2 atmosphere, a helium atmosphere, or a combination thereof.

[0060] Carbonization within the above temperature range helps to ensure the suppression of excessive Si particle growth, inhibits SiC formation, and simultaneously enhances the electrical conductivity of amorphous carbon. Through carbonization, the amorphous carbon precursor can be converted into amorphous carbon, which can surround the surface of secondary particles, thereby preparing an amorphous carbon layer. Some amorphous carbon can be inserted into the pores formed between primary particles to lie on the surface of the primary particles, thus surrounding the surface of the primary particles. Maintaining the carbonization atmosphere under the above conditions helps to effectively suppress silicon oxidation and SiC formation, thereby reducing the resistivity of the active material.

[0061] The heat-treated product can then be pulverized. Pulverization can be carried out using a sieve to make the span (defined by Equation 1) of the negative electrode active material about 1.1 to about 1.6. In practice, pulverization can be performed to obtain an active material having a particle size such that the span obtained by the D10, D50 and D90 of the active material is about 1.1 to about 1.6.

[0062] Another implementation provides a rechargeable lithium battery comprising a negative electrode, a positive electrode, and an electrolyte.

[0063] The negative electrode may include a current collector and a negative electrode active material layer, the negative electrode active material layer being on the current collector and including a negative electrode active material layer containing a negative electrode active material according to one embodiment.

[0064] According to some embodiments, the negative electrode active material may include the negative electrode active material as a first negative electrode active material, and may include crystalline carbon as a second negative electrode active material. The mixing ratio of the first negative electrode active material and the second negative electrode active material may be from about 80:20 to about 90:10 by weight. In an embodiment, the negative electrode active material may include the first negative electrode active material and the second negative electrode active material in a weight ratio of about 85:15 to about 90:10.

[0065] In the negative electrode active material layer, based on a total of 100% by weight of negative electrode active material layer, the amount of negative electrode active material can be from about 95% by weight to about 98% by weight.

[0066] In implementation, the negative electrode active material layer may include a binder and may further include a conductive material. Based on a total of 100% by weight of the negative electrode active material layer, the amount of binder may be from about 1% by weight to about 5% by weight. Based on a total of 100% by weight of the negative electrode active material layer, the amount of conductive material may be from about 1% by weight to about 5% by weight.

[0067] Binders help improve the adhesion properties between the active material particles of the negative electrode and with the current collector. Binders can be non-aqueous binders, aqueous binders, or combinations thereof.

[0068] Non-aqueous adhesives may include ethylene-propylene copolymers, polyacrylonitrile, polystyrene, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0069] Waterborne adhesives may include styrene-butadiene rubber (SBR), acrylated styrene-butadiene rubber (ABR), acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polypropylene, polyepoxygenated alcohol, polyphosphazene, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, or combinations thereof.

[0070] The negative electrode binder may include a cellulose compound, and may include the cellulose compound together with an aqueous binder. The cellulose compound may include one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or alkali metal salts thereof. The alkali metal may be Na, K, or Li. The cellulose compound can be used as a thickener and also as a binder. In practice, it can be used by appropriately adjusting it within the range of the binder described above, and therefore it is not required to be limited thereto, but for example, based on 100 parts by weight of the negative electrode active material, the amount of cellulose compound may be from about 0.1 parts by weight to about 3 parts by weight.

[0071] Conductive materials can impart conductivity to electrodes, and suitable materials that do not cause chemical changes and conduct electrons can be used in batteries. Examples include carbon materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fibers; metallic materials in the form of metal powders or metal fibers, including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0072] Current collectors may include, but are not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrates coated with conductive metals, and combinations thereof.

[0073] The positive electrode may include a current collector and a layer of positive electrode active material on the current collector. The positive electrode active material may include a lithiation intercalation compound that reversibly inserts and deintercalates lithium ions. In embodiments, at least one composite oxide of lithium and a metal (e.g., cobalt, manganese, nickel, or combinations thereof) may be used. In embodiments, a compound represented by one of the following chemical formulas may be used: Li a A 1-b X b D 1 2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5); Li a A 1-b X b O 2-c1 D 1 c1 (0.90≤a≤1.8, 0≤b≤0.5, 0≤c1≤0.05); Li a E 1-b X b O 2-c1 D 1 c1 (0.90≤a≤1.8, 0≤b≤0.5, 0≤c1≤0.05); Li a E 2-b X b O 4- c1 D 1 c1(0.90≤a ≤1.8,0≤b≤0.5,0≤c1≤0.05);Li a Ni 1-b-c Co b X c D 1 α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α≤2);Li a Ni 1-b-c Co b X c O 2-α T α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2);Li a Ni 1-b-c Co b X c O 2-α T2 (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2);Li a Ni 1-b- c Mr b X c D 1 α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α≤2);Li a Ni 1-b-c Mr b X c O 2-α T α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2);Li a Ni 1-b-c Mr b X c O 2-α T2 (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2);Li a Ni b HAVE BEEN c G d O2 (0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0.001≤d≤0.1);Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0≤d≤0.5,0≤e≤0.1);Lia NiG b O2 (0.90≤a≤1.8,0.001≤b≤0.1) Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); QO2; QS2; LiQS2; V2O5; LiV2O5; LiZO2; LiNiVO4; Li (3-f) J2(PO4)3 (0≤f≤2); Li (3-f) Fe2(PO4)3 (0≤f≤2); Li a FePO4 (0.90≤a≤1.8).

[0074] In the above chemical formulas, A is selected from Ni, Co, Mn, or combinations thereof; X is selected from Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or combinations thereof; D 1 Selected from O, F, S, P or combinations thereof; E selected from Co, Mn or combinations thereof; T selected from F, S, P or combinations thereof; G selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or combinations thereof; Q selected from Ti, Mo, Mn or combinations thereof; Z selected from Cr, V, Fe, Sc, Y or combinations thereof; J selected from V, Cr, Mn, Co, Ni, Cu or combinations thereof; L 1 Selected from Mn, Al, or combinations thereof.

[0075] These compounds may have a coating layer on the surface, or may be mixed with other compounds that have a coating layer. The coating layer may include a coating element compound, such as an oxide of the coating element, a hydroxide of the coating element, a hydroxy oxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element. The compound used for the coating layer may be amorphous or crystalline. The coating element included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer can be formed by using these elements in the compound in a manner that does not adversely affect the properties of the positive electrode active material, and the method may include any coating method such as spraying, dipping, etc., but will not be described in more detail because it is well known in the relevant art.

[0076] In the positive electrode, the amount of positive electrode active material can be from about 90% to about 98% by weight, based on the total weight of the positive electrode active material layer.

[0077] In practice, the positive electrode active material layer may further include a binder and a conductive material. Based on the total amount of the positive electrode active material layer, the binder and conductive material may each be included in an amount of about 1% to about 5% by weight.

[0078] Binders can help improve the adhesion properties between the active material particles of the positive electrode and with the current collector. Examples of binders may include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide (polymers containing ethylene oxide), polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0079] Conductive materials can provide electrode conductivity, and suitable electrically conductive materials can be used as conductive materials unless they cause a chemical change. Examples of conductive materials may include carbon materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.; metallic materials including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0080] The current collector may include, but is not limited to, Al.

[0081] Electrolytes may include non-aqueous organic solvents and lithium salts.

[0082] Non-aqueous organic solvents can be used as media for transporting ions that participate in the electrochemical reactions of a battery.

[0083] Non-aqueous organic solvents may include carbonates, esters, ethers, ketones, alcohols, or aprotic solvents.

[0084] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolactone, valproic acid lactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc., and ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include nitriles such as R-CN (where R may be a C2 to C20 straight-chain, branched or cyclic hydrocarbon group, and may include double bonds, aromatic rings or ether bonds, etc.); amides such as dimethylformamide; dioxolane such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane, etc.

[0085] Organic solvents can be used alone or in mixtures. In practice, organic solvents can be used in mixtures, and the mixing ratio can be controlled according to the desired battery performance, which is well known to those skilled in the art.

[0086] In practice, non-aqueous organic solvents may be mixed and used, including mixed solvents of cyclic carbonates and chain carbonates, mixed solvents of cyclic carbonates and propionate solvents, or mixed solvents of cyclic carbonates, chain carbonates, and propionate solvents. Propionate solvents may include methyl propionate, ethyl propionate, propyl propionate, or combinations thereof.

[0087] In practice, cyclic carbonates and linear carbonates, or cyclic carbonates and propionate solvents, can be mixed in a volume ratio of about 1:1 to about 1:9, thus improving the performance of the electrolyte solution. Alternatively, cyclic carbonates, linear carbonates, and propionate solvents can be mixed in a volume ratio of about 1:1:1 to about 3:3:4. The mixing ratio of the solvents can be appropriately adjusted according to the desired properties.

[0088] In practice, the organic solvent may further include aromatic hydrocarbon solvents and carbonate solvents. The carbonate solvents and aromatic hydrocarbon solvents may be mixed together in a volume ratio of about 1:1 to about 30:1.

[0089] Aromatic hydrocarbon organic solvents can be aromatic hydrocarbon compounds represented by chemical formula 1.

[0090] [Chemical Formula 1]

[0091]

[0092] In Formula 1, R1 to R6 may each be or include hydrogen, halogen, C1 to C10 alkyl, haloalkyl or a combination thereof.

[0093] In practice, aromatic hydrocarbon organic solvents may include benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, toluene, and fluorotoluene. 2,3-Difluorotoluene, 2,4-Difluorotoluene, 2,5-Difluorotoluene, 2,3,4-Trifluorotoluene, 2,3,5-Trifluorotoluene, Chlorotoluene, 2,3-Dichlorotoluene, 2,4-Dichlorotoluene, 2,5-Dichlorotoluene, 2,3,4-Trichlorotoluene, 2,3,5-Trichlorotoluene, Iodotoluene, 2,3-Diiodotoluene, 2,4-Diiodotoluene, 2,5-Diiodotoluene, 2,3,4-Triiodotoluene, 2,3,5-Triiodotoluene, Xylene, or combinations thereof.

[0094] In practice, the electrolyte may further include vinyl ethyl carbonate, vinylene carbonate, or a compound of ethylene carbonate represented by Formula 2 as an additive to improve cycle life.

[0095] [Chemical Formula 2]

[0096]

[0097] In Formula 2, R7 and R8 may each be independently or include hydrogen, halogen, cyano (CN), nitro (NO2) or C1 to C5 fluoroalkyl, provided that at least one of R7 and R8 is or includes halogen, cyano (CN), nitro (NO2) or C1 to C5 fluoroalkyl, and R7 and R8 are not simultaneously hydrogen.

[0098] In embodiments, the ethylene carbonate compound may include difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, brominated ethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, fluoroethylene carbonate, etc. The amount of the additive used to improve cycle life characteristics may be within a suitable range.

[0099] Lithium salts dissolved in organic solvents can supply lithium ions to batteries, essentially enabling the operation of rechargeable lithium batteries, and can help improve lithium ion transport between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO2C2F5)2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide: LiFSI), LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiN(C x F 2x+1 SO2)(C y F 2y+1 The lithium salts can be selected from various concentrations, including SO2 (where x and y are natural numbers, such as integers from about 1 to about 20), lithium difluoro(bis(oxalate)phosphate), LiCl, LiI, LiB(C2O4)2 (lithium bis(oxalate)borate) (LiBOB), or lithium difluoro(oxalate)borate (LiDFOB). The concentration of the lithium salt can range from about 0.1 M to about 2.0 M. Maintaining the lithium salt concentration within this range helps ensure that the electrolyte exhibits excellent performance and lithium-ion mobility due to optimal electrolyte conductivity and viscosity.

[0100] Depending on the type of rechargeable lithium battery, the separator may be located between the positive and negative electrodes. The separator may comprise polyethylene, polypropylene, polyvinylidene fluoride, or multilayers thereof having two or more layers, and may be a hybrid multilayer such as a polyethylene / polypropylene bilayer separator, a polyethylene / polypropylene / polypropylene trilayer separator, a polypropylene / polypropylene / polypropylene trilayer separator, etc.

[0101] Figure 1 This is an exploded perspective view of a rechargeable lithium battery according to an embodiment. In the embodiment, as shown in the accompanying drawings, the rechargeable lithium battery may be a prismatic battery, or may include batteries of various shapes such as cylindrical batteries, pouch batteries, etc.

[0102] like Figure 1 As shown, the rechargeable lithium battery 100 according to an embodiment may include an electrode assembly 40 manufactured by means of a separator 30 wound between a positive electrode 10 and a negative electrode 20, and a housing 50 for accommodating the electrode assembly 40. An electrolyte (not shown) may be impregnated in the positive electrode 10, the negative electrode 20, and the separator 30.

[0103] Mode for carrying out the present invention

[0104] Embodiments and comparative examples of the invention are described below. However, these embodiments are not to be construed as limiting the scope of the invention in any way.

[0105] (Example 1)

[0106] In ethanol solvent, silicon particles with an average particle size of 8 μm, nano-sized Ag, and stearic acid dispersant were mixed by pulverizing with zirconia balls for 8 hours. This process prepared primary silicon particles with an average particle size D50 of 100 nm. The mixing ratio of silicon particles to stearic acid dispersant was set to a weight ratio of silicon particles to stearic acid dispersant of 100:25, and the amount of Ag was adjusted to have a silicon to Ag weight ratio of 100:20.

[0107] The mixture was spray-dried to prepare secondary particles with an average particle size D50 of 7 μm and pores.

[0108] The prepared secondary particles and petroleum asphalt were mixed at a weight ratio of 60:40, and the mixture was carbonized at 1000°C under a N2 atmosphere.

[0109] The carbonized products were then pulverized to the span shown in Table 1 to prepare the negative electrode active material.

[0110] The prepared negative electrode active material includes: secondary particles with an average particle size D50 of 7 μm, wherein primary silicon particles with an average particle size D50 of 100 nm are agglomerated and surrounded by Ag with a thickness of 20 nm (Ag coating thickness: 20 nm); and a soft carbon coating layer covering the primary and secondary particles and including Ag.

[0111] Based on the total weight of the negative electrode active material, the amount of Ag is 10% by weight, the amount of silicon nanoparticles is 50% by weight, and the amount of soft carbon is 40% by weight.

[0112] 97.5% by weight of the prepared negative electrode active material, 1.5% by weight of carboxymethyl cellulose and 1% by weight of styrene-butadiene rubber were mixed in an aqueous solvent to prepare a negative electrode active material slurry.

[0113] The negative electrode active material layer slurry is coated onto a Cu foil current collector, dried, and pressurized to prepare the negative electrode active material layer, thereby preparing the negative electrode.

[0114] Half-cell cells are manufactured using a negative electrode, a lithium metal counter electrode, and an electrolyte via a standard procedure. The electrolyte is a 1 M LiPF6 solution in a mixed solvent of ethylene carbonate and dimethyl carbonate (3:7 volume ratio).

[0115] A coin-shaped full cell was fabricated using a negative electrode, a LiCoO2 positive electrode, and an electrolyte. The electrolyte was a 1 M LiPF6 solution in a mixed solvent of ethylene carbonate and dimethyl carbonate (3:7 volume ratio).

[0116] (Example 2)

[0117] The negative electrode, half-cell, and coin-shaped full-cell were manufactured using the same procedure as in Example 1, except that the negative electrode active material was prepared by pulverizing the material to have a span of 1.5.

[0118] (Example 3)

[0119] The negative electrode, half-cell, and coin-shaped full-cell were manufactured using the same procedure as in Example 1, except that the negative electrode active material was prepared by using Zn instead of Ag, with a Zn content of 10% by weight and a span of 1.1.

[0120] (Example 4)

[0121] The negative electrode, half-cell, and coin-type full-cell were manufactured using the same procedure as in Example 1, except that: Ag was used in a silicon-Ag mixture with a weight ratio of 100:6 to prepare a negative electrode active material having the following characteristics: a span of 1.1; an amount of Ag of 3 wt% based on the total weight of the negative electrode active material; secondary particles with an average particle size D50 of 7 μm, wherein primary silicon particles with an average particle size D50 of 100 nm were agglomerated and surrounded by a 5 nm thick Ag layer (Ag coating thickness: 5 nm); and a soft carbon coating layer including Ag was coated on the primary and secondary particles. In the prepared negative electrode active material, the amount of Ag was 3 wt%, the amount of silicon nanoparticles was 57 wt%, and the amount of soft carbon was 40 wt%.

[0122] (Comparative Example 1)

[0123] A negative electrode active material with a span of 1.1 was prepared without the use of Ag. The negative electrode, half-cell, and coin-shaped full-cell were then fabricated using the negative electrode active material following the same procedure as in Example 1.

[0124] (Comparative Example 2)

[0125] In ethanol solvent, silicon particles with an average particle size of 8 μm and stearic acid dispersant were pulverized for 8 hours using zirconia balls. This process prepared primary silicon particles with an average particle size D50 of 100 nm. The mixing ratio of silicon particles to stearic acid dispersant was set to a weight ratio of silicon particles:stearic acid dispersant of 100:25.

[0126] Nano-sized Ag was added to the resulting product at a weight ratio of 100:20 for silicon and Ag, and then spray-dried to prepare secondary particles with an average particle size D50 of 7 μm and pores.

[0127] The prepared secondary particles were initially heat-treated at 350°C for 1 hour in air atmosphere.

[0128] The prepared secondary particles and petroleum asphalt were mixed at a weight ratio of 60:40, and the mixture was carbonized at 1000°C under N2 atmosphere to prepare the negative electrode active material.

[0129] The prepared negative electrode active material includes: secondary particles with an average particle size D50 of 7 μm, wherein primary silicon particles with an average particle size D50 of 100 nm are agglomerated, and Ag is in point contact with the surface of the primary particles; and a soft carbon coating layer covering the primary and secondary particles and including Ag.

[0130] Based on the total weight of the negative electrode active material, the amount of Ag is 10% by weight, the amount of silicon nanoparticles is 50% by weight, and the amount of soft carbon is 40% by weight.

[0131] The negative electrode, half-cell, and coin-shaped full-cell were manufactured using the same procedure as in Example 1, with the negative electrode active material.

[0132] (Comparative Example 3)

[0133] In ethanol solvent, silicon particles with an average particle size of 8 μm and stearic acid dispersant were pulverized for 8 hours using zirconia balls. This process prepared primary silicon particles with an average particle size D50 of 100 nm. The mixing ratio of silicon particles to stearic acid dispersant was set to a weight ratio of silicon particles:stearic acid dispersant of 100:25.

[0134] The resulting product was spray-dried to prepare secondary particles with an average particle size D50 of 7 μm and pores.

[0135] The prepared secondary particles and petroleum asphalt were mixed at a weight ratio of 60:40, and the mixture was carbonized at 1000°C under N2 atmosphere to prepare a Si-carbon composite. The Si-carbon composite comprises: secondary particles with an average particle size D50 of 7 μm, wherein primary silicon particles with an average particle size D50 of 100 nm are agglomerated; and a soft carbon coating layer covering the primary and secondary particles.

[0136] The negative electrode active material was prepared by mixing Si-carbon composite and Ag at a weight ratio of 100:10.

[0137] The negative electrode, half-cell, and coin-shaped full-cell were manufactured using the same procedure as in Example 1, with the negative electrode active material.

[0138] (Comparative Example 4)

[0139] Silicon primary particles with an average particle size of 100 nm D50 were prepared by pulverizing silicon particles with an average particle size of 8 μm and stearic acid dispersant using zirconia balls for 8 hours.

[0140] Primary silicon particles were mixed with Ag2Si and then spray-dried to prepare secondary particles with an average particle size D50 of 7 μm and pores.

[0141] Use the amount of Ag2Si so that the amount of Ag is 10 by weight based on a total of 100% by weight of the final negative electrode active material.

[0142] The prepared secondary particles and petroleum asphalt were mixed at a weight ratio of 60:40, and the mixture was carbonized at 1000°C under N2 atmosphere to prepare the negative electrode active material.

[0143] The prepared negative electrode active material includes: secondary particles with an average particle size D50 of 7 μm, which include primary silicon particles with an average particle size D50 of 100 nm agglomerated with Ag2Si; and a soft carbon coating layer covering the primary and secondary particles and including Ag.

[0144] The negative electrode, half-cell, and coin-shaped full-cell were manufactured using the same procedure as in Example 1, with the negative electrode active material.

[0145] Experimental Example 1: Evaluation of Span

[0146] The D10, D50, and D90 of the negative electrode active materials of Examples 1 to 4 and Comparative Examples 1 to 4 were measured using a particle analyzer (product name: LS 13 320, manufacturer: Beckman Coulter). The results are shown in Table 1. The span defined by Equation 1 was obtained from these values. The results are shown in Table 1.

[0147] Experimental Example 2: Evaluation of XRD Characteristics of the Active Material of the Negative Electrode

[0148] Regarding the negative electrode active materials of Examples 1 to 4 and Comparative Examples 1 to 4, X-ray diffraction analysis (XRD) was performed using CuKα rays to obtain the peak intensity (I) at the (111) plane of Ag. Ag(111) ) relative to the peak intensity (I) at the (111) plane of Si Si(111) Peak intensity ratio (I) Ag(111) / I Si(111) Peak intensity ratio is defined as the ratio of peak height. The results of Examples 1 to 4 and Comparative Examples 2 to 4 are shown in Table 1.

[0149] Experiment Example 3: Evaluation of Charging and Discharging Efficiency

[0150] The half-cells according to Examples 1 to 4 and Comparative Examples 1 to 4 were charged and discharged once at 0.1C, and the ratio of the measured discharge capacity to the measured charge capacity was calculated. The results are shown as efficiency in Table 1.

[0151] Experiment Example 4: Evaluation of Rate Capacity Performance

[0152] The half-cells according to Examples 1 to 4 and Comparative Examples 1 to 4 were charged and discharged once at 0.2C, and then charged and discharged once at 2C. The ratio of the charging capacity at 2C to the charging capacity at 0.2C was calculated. The results are shown in Table 1 as charging rate performance.

[0153] Experimental Example 5: Evaluation of Accelerated Lifespan

[0154] The coin-type full-cell batteries according to Examples 1 to 3 and Comparative Examples 1 to 5 were charged and discharged for 500 cycles at 1C. The ratio of the discharge capacity at the 500th cycle to the discharge capacity at the 1st cycle was calculated. The results are shown in Table 1.

[0155] Table 1

[0156]

[0157] As shown in Table 1, the battery cells including the negative electrode active materials of Examples 1 to 4 exhibit high efficiency and charge rate performance, as well as excellent accelerated life. However, Comparative Example 1, which does not include Ag, exhibits degraded charge rate performance and accelerated life.

[0158] Comparative Example 2, in which Ag is disposed in surface point contact with silicon primary particles, exhibits low charge and discharge efficiency. Comparative Example 3, using a negative electrode active material in which Si-carbon composite and Ag are simply mixed, exhibits significantly low charge and discharge efficiency and low charge rate performance, and shows a significantly degraded accelerated lifetime of 6.1%.

[0159] Comparative Example 4, which uses a negative electrode active material that is a mixture of Si-carbon composites and Si-Ag compounds, shows extremely degraded charge and discharge efficiency, charge rate performance, and accelerated life.

[0160] While this disclosure has been described with respect to exemplary embodiments which are now considered practical, it will be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover a variety of modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. Negative electrode active material, including: The span defined by Equation 1 is approximately 1.1 to approximately 1.

6. The primary particles consist of secondary particles formed by the aggregation of primary particles, wherein the primary particles include silicon nanoparticles and a metal coating layer comprising a metallic material surrounding the surface of each silicon nanoparticle; and An amorphous carbon coating layer surrounding the surfaces of the primary particles and the secondary particles. [Equation 1] Span = (D90 - D10) / D50 (Where, D10 represents the diameter of a particle with a cumulative volume of 10% in the particle size distribution, D50 represents the diameter of a particle with a cumulative volume of 50% in the particle size distribution, and D90 represents the diameter of a particle with a cumulative volume of 90% in the particle size distribution).

2. The negative electrode active material according to claim 1, wherein the metal material comprises a metal or a metal compound.

3. The negative electrode active material according to claim 2, wherein the metal compound comprises metal oxides, metal nitrides, or combinations thereof.

4. The negative electrode active material according to claim 1, wherein the metal material comprises a metal capable of alloying with lithium.

5. The negative electrode active material according to claim 4, wherein the metal includes alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, or combinations thereof.

6. The negative electrode active material according to claim 5, wherein the metal comprises Ag, 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, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or combinations thereof.

7. The negative electrode active material according to claim 6, wherein the metal comprises Ag.

8. The negative electrode active material according to claim 1, wherein the amount of the metal material is from about 0.01% by weight to about 20% by weight, based on the total weight of the negative electrode active material.

9. The negative electrode active material according to claim 1, wherein the amount of the metal material is from about 0.05% by weight to about 15% by weight, based on the total weight of the negative electrode active material.

10. The negative electrode active material according to claim 1, wherein the amorphous carbon coating layer further comprises another metallic material.

11. The negative electrode active material according to claim 7, wherein, in the measurement of X-ray diffraction intensity, the negative electrode active material has a diffraction peak intensity (I0.05 to about 0.5) originating from Ag(111) detected at 2θ = about 37.5° to about 40.0°. Ag(111) The intensity of the diffraction peak originating from Si(111) detected at 2θ = approximately 27.5° to approximately 29.5° is (I) Si(111) Peak intensity ratio (I) Ag(111) / I Si(111) ).

12. The negative electrode active material according to claim 1, wherein the metal coating layer continuously covers the respective surfaces of the silicon nanoparticles.

13. The negative electrode active material according to claim 1, wherein the metal coating layer has a thickness of about 1 nm to about 30 nm.

14. The negative electrode active material according to claim 1, wherein the silicon nanoparticles have a particle size of about 10 nm to about 1,000 nm.

15. The negative electrode active material according to claim 1, wherein the amorphous carbon coating layer has a thickness of about 1 nm to about 2 μm.

16. The negative electrode active material according to claim 1, wherein the amount of silicon nanoparticles is about 44% to about 65% by weight based on the total weight of the negative electrode active material.

17. The negative electrode active material according to claim 1, wherein the amount of the amorphous carbon coating layer is from about 34% to about 46% by weight, based on the total weight of the negative electrode active material.

18. A rechargeable lithium battery, comprising: A negative electrode comprising the negative electrode active material according to any one of claims 1 to 17; Positive electrode; and Electrolytes.

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