Positive electrode active material for lithium secondary battery, method for producing same, and lithium secondary battery comprising same
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- TOP MATERIAL CO LTD
- Filing Date
- 2025-12-10
- Publication Date
- 2026-06-25
Abstract
Description
A positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same
[0001] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same.
[0002]
[0003] Lithium-ion batteries are rechargeable batteries with excellent performance characteristics such as high capacity, high output, and long lifespan. They are not only widely used in small electronic products such as electronic devices, portable computers, and mobile phones, but are also being commercialized as large-scale power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs).
[0004] Lithium secondary batteries generally consist of a structure in which a non-aqueous electrolyte containing a lithium salt is impregnated into an electrode assembly in which a porous separator is interposed between a positive electrode and a negative electrode. Here, the positive and negative electrodes each have an active material coated on a current collector.
[0005] Recently, research on LFP (LiFePO4) has been actively conducted among the cathode active materials constituting the anode. LFP possesses an olivine or nasicon structure and offers not only a high theoretical capacity (170 mAh / g) but also the advantages of low cost and excellent stability.
[0006] However, since the diffusion path of lithium ions in LFP is limited to a single direction, lithium ion mobility becomes restricted as the grain size increases. This leads to a degradation in the capacity and power characteristics of LFP, posing limitations in applications requiring high power and fast charge / discharge performance. Consequently, many attempts have been made to improve lithium ion diffusivity by reducing the grain size.
[0007] Meanwhile, the conventional solid-state synthesis method using FePO₄ precursors has been used as a stable method suitable for large-scale production in LFP synthesis. This method synthesizes LFP by mixing lithium raw materials (e.g., Li₂CO₃) and iron phosphate raw materials (e.g., FePO₄) and performing a high-temperature sintering process.
[0008] This method has the advantage of a simple process and the ability to produce LFP of consistent quality, but it has limitations in controlling the size of primary particles and the crystal grains that constitute them. Furthermore, a significant amount of wastewater is generated in the process of manufacturing the phosphoric acid raw material, and since the wastewater contains large amounts of iron, phosphates, chemical additives, etc., it can be a major cause of environmental pollution.
[0009]
[0010] One embodiment is intended to provide an olivine or nasicon-based cathode active material that can be produced in an environmentally friendly manner while controlling the size of the primary particles and the size of the crystal grains constituting them.
[0011] Another embodiment provides a method for manufacturing the above positive active material.
[0012] Another embodiment provides a positive electrode comprising the above positive electrode active material.
[0013] Another embodiment provides a lithium secondary battery including the above positive electrode.
[0014]
[0015] One embodiment provides a positive active material for a lithium secondary battery comprising a secondary particle formed by the aggregation of olivine or nasicon-based primary particles; wherein the positive active material satisfies the following Equation 1; and wherein the positive active material may or may not contain Fe2P2O7, and the content of Fe2P2O7 is 1 weight% or less relative to the total amount of 100 weight% of the positive active material.
[0016] [Mathematical Formula 1]
[0017] 2.6 ≤ Y / X
[0018] In the above mathematical formula 1, X is the crystal grain size of the primary particle; and Y is the average particle size of the primary particle.
[0019]
[0020] Another embodiment provides a method for manufacturing a positive electrode active material for a lithium secondary battery, comprising the steps of: dry mixing lithium raw material, iron raw material, and phosphorus raw material; adding a solvent to the dry mixture and wet mixing; grinding the wet mixture; spray-drying the wet-ground material; and calcining the spray-dried material, wherein a flux is added together with the solvent during the wet mixing.
[0021]
[0022] Another embodiment provides a positive electrode for a lithium secondary battery, comprising: a positive current collector; and a positive active material layer positioned on the positive current collector and comprising the positive active material.
[0023]
[0024] Another embodiment provides a positive electrode for a lithium secondary battery comprising the above positive electrode; a negative electrode; and an electrolyte.
[0025]
[0026] According to one embodiment, an olivine or nasicon-based cathode active material can be provided in an eco-friendly manner while controlling the size of the primary particles and the size of the crystal grains constituting them.
[0027] Furthermore, by using the positive electrode active material according to one embodiment, high-performance positive electrodes and lithium secondary batteries can be provided in an eco-friendly manner.
[0028]
[0029] Specific embodiments are described below in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.
[0030] The terms used herein are for describing exemplary embodiments only and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.
[0031] "Combinations of these" refers to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.
[0032] Terms such as "include," "equip," or "have" are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.
[0033] In the drawings, thicknesses have been enlarged to clearly represent various layers and regions, and the same reference numerals have been used for similar parts throughout the specification. When a part such as a layer, film, region, or plate is described as being "on" or "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately on" another part, it means that there is no other part in between.
[0034] “Layers” include not only shapes formed on the entire surface when viewed in a plan view, but also shapes formed on some surfaces.
[0035] “Particle size” or “average particle size” may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with transmission electron microscope images or scanning electron microscope images. Alternatively, the average particle size value may be obtained by measuring using dynamic light scattering and performing data analysis to count the number of particles for each particle size range, and then calculating from this. Unless otherwise defined, the average particle size may be a value derived by measuring the particle size using scanning electron microscope images and taking the average. Meanwhile, D50 may refer to the diameter of a particle in which the cumulative volume is 50% by volume in the particle size distribution.
[0036]
[0037] (Cathode active material)
[0038] The diffusion patterns of lithium ions according to the crystal structure of the positive electrode active material are as follows: the positive electrode active material with the olivine or nasicon structure is a 1D diffusion pattern that diffuses only along the b-axis, whereas the positive electrode active material with the layered structure is a 2D diffusion pattern that diffuses lithium ions in the a-axis and b-axis directions; and the positive electrode active material with the spinel structure is a 3D diffusion pattern that diffuses lithium ions along the a-axis, b-axis, and c-axis.
[0039] Accordingly, compared to cathode active materials with other structures, such as LCO (LiCoO2), NCM (Li(Ni-Co-Mn)O2), and NCA (Li(Ni-Co-Al)O2) having layered structures, and LMO (LiMn2O4) having spinel structures, LFP has low lithium ion conductivity, which poses a problem that impedes the output performance of lithium secondary batteries.
[0040]
[0041] In relation to the above, methods have been proposed to increase the diffusion path of lithium ions by reducing the grain size of LFP to increase the grain boundaries; and to reduce the diffusion length of lithium ions by reducing the primary particle size of LFP.
[0042] However, while these methods have the advantage of improving reaction rates by increasing the diffusion rate of lithium ions, they require an excess amount of solvent in the electrode manufacturing process in proportion to the increased specific surface area, which lowers processability and productivity, and also causes a problem of reduced lifespan of the lithium secondary battery due to reduced grain size and / or reduced size of primary particles.
[0043]
[0044] Another method proposed involves modifying the crystal structure by adding dopants to the olivine or nasicon structures of LFP (i.e., shortening the length of the b-axis, which is the direction of lithium ion diffusion, or lengthening the a-axis, which is the entrance through which lithium ions pass).
[0045] However, as dopants are added, process difficulty and costs increase, and there is a problem where the lifespan of lithium secondary batteries decreases due to the crystal structure becoming unstable as a result of the added dopants.
[0046]
[0047] Accordingly, one embodiment decided to consider various factors regarding the crystal structure of LFP.
[0048] A specific embodiment provides a positive active material for a lithium secondary battery comprising a secondary particle aggregated from olivine or nasicon-based primary particles; wherein the positive active material satisfies the following mathematical formula 1; and wherein the positive active material may or may not contain Fe2P2O7, and the content of Fe2P2O7 is 1 weight% or less relative to the total amount of 100 weight% of the positive active material.
[0049] [Mathematical Formula 1]
[0050] 2.6 ≤ Y / X
[0051] In the above mathematical formula 1, X is the crystal grain size of the primary particle; and Y is the average particle size of the primary particle.
[0052]
[0053] The positive electrode active material according to the above embodiment can increase the size of the primary particles relative to the crystal grain size by satisfying the above mathematical formula 1 without using a separate dopant, and can secure a stable lifespan of the lithium secondary battery.
[0054] In addition, as will be described in more detail later, the positive active material according to the above embodiment can be obtained in an environmentally friendly manner by using separate phosphorus and iron raw materials instead of an FePO₄ precursor.
[0055]
[0056] In short, according to one embodiment, an olivine or nasicon-based cathode active material can be provided in an environmentally friendly manner while controlling the size of the primary particles and the size of the crystal grains constituting them. Furthermore, by using the cathode active material according to one embodiment, high-performance cathodes and lithium secondary batteries can be provided in an environmentally friendly manner.
[0057]
[0058] Hereinafter, a positive electrode active material according to one embodiment will be described in detail.
[0059]
[0060] Mathematical formula 1
[0061] The above positive active material may satisfy the above mathematical formula 1, and the above mathematical formula 1 may be the following mathematical formulas 1-1, 1-2, 1-3, or 1-4:
[0062] [Mathematical Formula 1-1]
[0063] 2.6 ≤ Y / X ≤ 7
[0064] [Mathematical Formula 1-2]
[0065] 2.7 ≤ Y / X ≤ 6.5
[0066] [Mathematical Formula 1-3]
[0067] 2.8 ≤ Y / X ≤ 6.3
[0068] [Mathematical Formula 1-4]
[0069] 3 ≤ Y / X ≤ 4
[0070] As the above positive active material satisfies Equation 1, exemplified by 1-1, 1-2, 1-3, or 1-4, the size of the primary particle relative to the crystal grain size is increased without using a separate dopant, and a stable lifespan of the lithium secondary battery can be secured.
[0071]
[0072] Mathematical formula 2
[0073] Furthermore, the above-mentioned positive active material may further satisfy the following mathematical formula 2:
[0074] [Mathematical Formula 2]
[0075] 28 m 2 / g ≤ (Y / X)*Z
[0076] In the above mathematical formula 2, the definitions of X and Y are as previously stated; and Z is the specific surface area of the positive active material.
[0077]
[0078] In conventional solid-state synthesis methods using FePO₄ precursors, a decrease in primary particle size increases the specific surface area of the electrode, thereby expanding the contact area with the electrolyte and activating side reactions such as the formation of a Solid Electrolyte Interphase (SEI) layer. This leads to reduced electrochemical stability of the electrode and negatively affects long-term cycle life. This issue acts as a major factor degrading the efficiency and reliability of LFP in high-performance battery applications.
[0079] On the other hand, the cathode active material according to one embodiment can improve the efficiency and reliability of LFP by increasing the size of the primary particles relative to the grain size, while increasing the specific surface area to an appropriate range.
[0080]
[0081] The above mathematical formula 2 may be the following mathematical formulas 2-1, 2-2, 2-3, or 2-4:
[0082] [Mathematical Formula 2-1]
[0083] 28 m 2 / g ≤ (Y / X)*Z ≤ 60
[0084] [Mathematical Formula 2-2]
[0085] 28.5 m 2 / g ≤ (Y / X)*Z ≤ 59
[0086] [Mathematical Formula 2-3]
[0087] 29 m 2 / g ≤ (Y / X)*Z ≤ 58
[0088] [Mathematical Formula 2-4]
[0089] 33 m 2 / g ≤ (Y / X)*Z ≤ 51
[0090] As the above-mentioned positive active material additionally satisfies Equation 2, exemplified by 2-1, 2-2, 2-3, or 2-4, the size of the primary particle relative to the crystal grain size is increased, and the specific surface area is raised to an appropriate range, thereby improving the efficiency and reliability of the LFP.
[0091]
[0092] X, Y, and Y value
[0093] The above X value may be, for example, 78.5 to 95 nm, 79 to 94.5 nm, 79.5 to 94 nm, or 78.6 to 79.5 nm.
[0094] The above Y value may be, for example, 218 to 600 nm, 219 to 595 nm, 220 to 590 nm, or 240 to 416 nm.
[0095] The above Z value is, for example, 9 to 12 m 2 / g, 9.1 to 12 m 2 / g, 9.2 to 11 m 2 / g, or 9.5 to 10.99 m 2 It can be / g.
[0096] When the above ranges are satisfied, the above-mentioned mathematical formula 1 may be satisfied and / or the above-mentioned mathematical formulas 1 and 2 may be satisfied simultaneously.
[0097]
[0098] Impurity content
[0099] The above positive active material may not contain any impurities.
[0100]
[0101] However, when the above-mentioned positive active material contains impurities, it may include Fe2P2O7 and optionally further include Li3PO4.
[0102] For example, the content of Fe2P2O7 relative to the total amount of 100 wt% of the cathode active material may be 1 wt% or less, 0.9 wt% or less, or 0.3 wt% or less. The lower limit is not specifically limited, but may be 0 wt% (not containing any Fe2P2O7), 0.3 wt% or more, or 0.6 wt% or more.
[0103] In addition, the content of Li3PO4 relative to the total amount of 100 wt% of the cathode active material may be 1.2 wt% or less, 0.9 wt% or less, or 0.6 wt% or less. The lower limit is not specifically limited, but may be 0 wt% (not containing any Li3PO4) or 0.6 wt% or more.
[0104]
[0105] chemical formula
[0106] The above primary particle can be represented by the following chemical formula 1.
[0107] [Chemical Formula 1]
[0108] Li a Fe x M y PO 4-b X b
[0109] In the above chemical formula 1,
[0110] 0.9≤a≤1.1, 0.1≤x≤1, 0≤y≤0.9, and 0≤b≤0.1, and
[0111] M is one or more elements selected from the group consisting of Al, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Ti, V, Zn, Nb, and Zr, and
[0112] X is one or more elements selected from the group consisting of F and Cl.
[0113]
[0114] For example, the above chemical formula 1 may be LiFePO4.
[0115]
[0116] Particle size of secondary particles constituting the positive electrode active material
[0117] The average particle size of the above secondary particles may be 1 to 100 μm, specifically 5 to 50 μm, more specifically 10 to 20 μm.
[0118] The shape of the above secondary particles may be spherical, and pores may exist between different primary particles.
[0119]
[0120] coating layer
[0121] The above positive active material has the above secondary particle as a core; and may further include a carbon coating layer located on the above secondary particle.
[0122]
[0123] For example, the content of the carbon coating layer relative to 100 weight% of the total weight of the positive electrode active material may be 0.1 to 5 weight%, 0.5 to 3 weight%, or 1 to 2.5 weight%.
[0124] Within the above range, the insufficient electrical conductivity of LFP can be effectively compensated for.
[0125]
[0126] (Method for manufacturing a positive electrode active material for a lithium secondary battery)
[0127] Another embodiment provides a method for manufacturing a positive electrode active material for a lithium secondary battery, comprising the steps of: dry mixing lithium raw material, iron raw material, and phosphorus raw material; adding a solvent to the dry mixture and wet mixing; grinding the wet mixture; spray-drying the wet-ground material; and calcining the spray-dried material, wherein a flux is added together with the solvent during the wet mixing.
[0128]
[0129] The positive electrode active material of the above-described embodiment can be manufactured according to the manufacturing method of one embodiment. Hereinafter, descriptions that overlap with the above content will be omitted, and the manufacturing method of the above-described embodiment will be described in detail step by step.
[0130]
[0131] flux
[0132] The above flux may help dissolve the raw materials in the solvent, lower surface tension during the sintering process, suppress the growth of crystal grains formed accordingly, and increase the average particle size of the primary particles, thereby improving the diffusion of lithium ions in the final cathode active material.
[0133]
[0134] The above flux may be a non-metallic fluoride, for example, NH3F.
[0135]
[0136] The content of the flux relative to the total amount of solids comprising the lithium raw material, the iron raw material, the phosphorus raw material, and the flux, which is 100% by weight, may be greater than 0% by weight and less than or equal to 10% by weight, greater than or equal to 0.5% by weight and less than or equal to 5% by weight, or greater than or equal to 2% by weight and less than or equal to 3% by weight. Within this range, the above-mentioned effect may be maximized.
[0137]
[0138] raw materials
[0139] The above lithium raw material may be any one compound selected from the group consisting of lithium oxides, hydroxides, nitrates, carbonates, acetates, and mixtures thereof, and may be, for example, Li2CO3.
[0140] The above iron raw material may be any one compound selected from the group consisting of iron oxides, hydroxides, nitrates, carbonates, and mixtures thereof, and may be, for example, Fe2O3.
[0141] The above phosphorus raw material may be any one compound selected from the group consisting of phosphorus oxides, hydroxides, nitrates, carbonates, ammonium mixed salts, hydrogen mixed salts, and mixtures thereof, and may be, for example, NH4H2PO4.
[0142] By using the phosphorus raw material and the iron raw material separately instead of the existing iron phosphate raw material (e.g., FePO4), olivine or nasicon-based cathode active materials can be produced in an environmentally friendly manner.
[0143]
[0144] The above lithium raw material and the above iron raw material may satisfy the following mathematical formulas 3, 3-1, and 3-2:
[0145] [Mathematical Equation 3] 0.9≤Li / Me≤1.8
[0146] [Mathematical Equation 3-1] 1≤Li / Me≤1.5
[0147] [Mathematical Formula 3-2] 1 <Li / Me≤1.3
[0148] In the above mathematical formulas 3, 3-1, and 3-2, Li is the number of moles of lithium in the lithium raw material, and Me is the number of moles of iron in the iron raw material.
[0149] LFP satisfying the aforementioned Chemical Formula 1 can be produced within the above range. In particular, considering the loss during the LFP production process, it may be desirable to use an excess amount of the lithium raw material.
[0150]
[0151] In addition to the above lithium raw material, the above phosphorus raw material, and the above iron phosphate raw material, a raw material for carbon coating (hereinafter, carbon raw material) may be added.
[0152] The above carbon raw material can be a sugar commonly used in the industry, for example, glucose can be used.
[0153] The amount of the above carbon raw material used can also be referenced from the amount generally used in the industry and controlled by considering the carbon content in the final cathode active material.
[0154]
[0155] menstruum
[0156] The above solvent is not particularly limited as long as it can dissolve the above raw materials, but may be ethanol.
[0157] The content of the solvent relative to the total amount of the wet mixture (100 weight%) may be 10 to 70 weight%, 20 to 60 weight%, or 30 to 50 weight%.
[0158]
[0159] Dry mixing step
[0160] In the above dry mixing step, a dry powder mixer can be used to mix the lithium raw material, the phosphate raw material, the iron raw material, and optionally the carbon raw material.
[0161]
[0162] Wet mixing step
[0163] In the above wet mixing step, the dry mixture can be mixed with the solvent, water (e.g., primary purified water or secondary purified water), using a stirrer.
[0164]
[0165] The content of the dry mixture relative to the total weight of the wet mixture (100 weight%) may be 10 to 70 weight%, specifically 10 to 60 weight%, more specifically 30 to 50 weight%.
[0166] If a wet mixture mixed within this range is used, the grinding step and the spray drying step can be carried out effectively.
[0167]
[0168] Wet grinding stage
[0169] The grinding step of the above wet mixture can be performed using a bead mill.
[0170]
[0171] The D50 particle size of the solid in the above wet pulverized material may be 200 to 500 nm, specifically 250 to 450 nm, more specifically 300 to 400 nm.
[0172] Within the above range, a positive electrode active material having a desired D50 particle size can be finally obtained. However, if the upper limit of the above range is exceeded, the reaction contact area of the wet pulverized material is low, so uniform synthesis may not be achieved, and if it falls below the lower limit of the above range, there may be no particular effect.
[0173]
[0174] The viscosity of the above wet pulverized material may be 1 to 500 CPs, specifically 10 to 480 CPs, and more specifically 30 to 450 CPs.
[0175] The wet pulverized material having such low viscosity as described above may be suitable for spray drying to produce spherical secondary particles.
[0176]
[0177] Spray drying step
[0178] The spray drying step of the above wet pulverized material can be performed using a spray drying device at an input temperature of 200 to 300 ℃, an output temperature of 100 to 120 ℃, and a pumping speed of 10 to 100 rpm.
[0179] In this range, wet-ground material may be suitable for spray-drying to produce spherical secondary particles.
[0180]
[0181] firing stage
[0182] The calcination step of the above-mentioned positive active material precursor can be performed using a high-temperature oven. For example, it can be performed at 500 to 900 ℃, specifically 600 to 800 ℃; for 2 to 20 hours, specifically 8 to 12 hours.
[0183] In this range, when the LFP precursor composed of the lithium raw material and the iron phosphate raw material is oxidized and converted into LFP, it is aggregated into secondary particles, and internal pores of the LFP secondary particles are formed by the multifunctional additive, and the multifunctional additive can also be carbonized and converted into the first coating layer and the second coating layer.
[0184]
[0185] Post-processing step
[0186] After the above calcination step, a step of sieve-classifying the obtained positive electrode active material may be further included. Additionally, after the sieve-classifying step, a step of packaging the classified positive electrode active material for product commercialization may be further included.
[0187]
[0188] (Cathode for lithium secondary batteries and lithium secondary batteries)
[0189] Another embodiment provides a positive electrode for a lithium secondary battery, comprising: a positive current collector; and a positive active material layer positioned on the positive current collector and comprising the positive active material.
[0190] Another embodiment provides a lithium secondary battery comprising the anode; the cathode; and the electrolyte.
[0191] By using the positive active material according to the above-described embodiment, high-performance positive and lithium secondary batteries can be provided at a low cost.
[0192]
[0193] Hereinafter, explanations that overlap with the above content will be omitted, and the above positive electrode and the above lithium secondary battery will be described in detail.
[0194]
[0195] anode
[0196] The above anode can be manufactured by applying an electrode mixture, which is a mixture of an anode active material, a conductive material, and / or a binder, onto an anode current collector and then drying it, and if necessary, a filler can be further added to the mixture.
[0197] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples include natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powders such as copper, nickel, aluminum, and silver, metal fibers, etc., and one or more types of conductive materials such as polyphenylene derivatives can be used in combination. The above conductive material may be included in an amount of 1 to 8 weight percent of the total weight of the anode composite.
[0198] The above binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto. The above binder may be included in an amount of 3 to 10 weight percent of the total weight of the above positive composite.
[0199] The above positive current collector can generally be made with a thickness of 3 to 500 μm. Such a positive current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. The current collector may also form fine irregularities on its surface to increase the adhesion of the positive active material, and various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics are possible.
[0200]
[0201] cathode
[0202] The above-mentioned cathode includes a current collector and a cathode active material layer formed on the current collector, and the cathode active material layer may include a cathode active material.
[0203] The above-mentioned negative electrode active material includes a carbon-based negative electrode active material, lithium metal, a lithium metal alloy, Si, and SiO. xAt least one negative electrode active material selected from the group comprising (0 < x ≤ 2), Si-C composite, Si-Q alloy (wherein Q is an alkali metal, alkaline earth metal, group 13 to 16 element, transition metal, rare earth element, or a combination thereof, and not Si), Sn, SnO2, Sn-C composite, and Sn-R (wherein R is an alkali metal, alkaline earth metal, group 13 to 16 element, transition metal, rare earth element, or a combination thereof, and not Sn).
[0204] The above-mentioned negative current collector can generally be manufactured with a thickness of 3 to 500 μm. Such a negative current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy may be used. In addition, similar to the positive current collector, fine irregularities may be formed on the surface to strengthen the bonding strength of the negative active material, and it may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.
[0205]
[0206] electrolytes
[0207] The lithium secondary battery of the above embodiment may be a lithium-ion battery, a lithium-ion polymer battery, or a lithium-polymer battery, depending on the type of electrolyte and / or the type of separator.
[0208] When the lithium secondary battery of the above embodiment is a lithium-ion battery using a liquid electrolyte, the liquid electrolyte can be impregnated into a separator. The separator is interposed between the positive and negative electrodes, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 μm, and the thickness is generally 5 to 300 μm. For example, olefin-based polymers such as chemically resistant and hydrophobic polypropylene; sheets or nonwoven fabrics made of glass fibers or polyethylene are used as such separators. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as the separator.
[0209] The above liquid electrolyte may be a lithium salt-containing non-aqueous electrolyte. The above lithium salt-containing non-aqueous electrolyte consists of a non-aqueous electrolyte and lithium, and the non-aqueous electrolyte may include a non-aqueous organic solvent, an organic solid electrolyte, an inorganic solid electrolyte, etc., but is not limited to these.
[0210] As the above-mentioned non-aqueous organic solvent, for example, aprotic organic solvents such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butylolactone, 1,2-dimethoxyethane, tetrahydroxyfranc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, methyl propionate, ethyl propionate, etc. may be used.
[0211] The above organic solid electrolyte may be, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, a polymer containing an ionic dissociator, etc.
[0212] As the above-mentioned inorganic solid electrolyte, for example, nitrides, halides, sulfates of Li such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2 may be used.
[0213] The above lithium salt is a substance that dissolves well in the above-mentioned non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl 10 LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium tetraphenylborate, imide, etc. may be used.
[0214] In addition, for the purpose of improving charge / discharge characteristics and flame retardancy, the above lithium salt-containing non-aqueous electrolyte may be supplemented with, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. In some cases, to impart non-flammability, halogen-containing solvents such as carbon tetrachloride and trifluoroethylene may be further included, and to improve high-temperature storage characteristics, carbon dioxide gas may be further included, and FEC (Fluoro-Ethylene Carbonate), PRS (Propene Sultone), etc. may be further included.
[0215] In one specific example, a lithium salt-containing non-aqueous electrolyte can be prepared by adding a lithium salt such as LiPF6, LiClO4, LiBF4, LiN(SO2CF3)2 to a mixed solvent of a cyclic carbonate of a high dielectric solvent such as EC or PC and a linear carbonate of a low viscosity solvent such as DEC, DMC, or EMC.
[0216]
[0217] lithium secondary battery
[0218] The lithium secondary battery of the above embodiment may be implemented as a battery module including the same as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.
[0219] In this case, specific examples of the above device may include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, or power storage systems.
[0220]
[0221] Hereinafter, embodiments and comparative examples of the present invention are described. However, the embodiments are merely examples of the present invention, and the present invention is not limited to these embodiments.
[0222]
[0223] Comparative Example 1 (Ref.)
[0224] (1) Synthesis of FePO4
[0225] Prepare solutions of iron(III) chloride FeCl3 (alpha-A4 purity 99% or higher) and phosphoric acid H3PO4 (sam-Jeon-Seon-Yang purity 99% or higher). FeCl3 provides the element iron, and H3PO4 acts as a source of phosphate.
[0226] The two solutions above are each prepared at an appropriate concentration and then mixed in a 1:1 molar ratio. Since pH control is important during this mixing process, water ammonia (NH4OH) is slowly added to maintain the pH at approximately 3 to 4. When adding the water ammonia, it is added slowly at a constant rate to prevent sudden changes in the pH of the solution and the formation of uneven precipitates.
[0227] The mixed solution is stirred for about 2 hours to ensure a uniform reaction, and during this stirring time, chemical reactions within the solution are induced to gradually form a yellowish-brown precipitate. Since the formed precipitate is FePO4 and contains a large amount of impurities and reaction solution, a total of 4 washes are performed using 200 times the amount of purified water in the washing step after the reaction is completed.
[0228] Residual impurities and reaction by-products are removed through the washing process, and in the filtration step, the washed precipitate is filtered out and the remaining water is removed. The filtered precipitate is dried at 100°C for more than 12 hours to obtain FePO4 powder in the form of a stable hydrate.
[0229] Afterwards, FePO4 in an anhydrated form is prepared by heat treatment at a temperature of 500°C to remove hydrates.
[0230] (2) Preparation of positive electrode active material
[0231] Li2CO3 (Manufacturer: Junsei, purity: 99% or higher) as a lithium raw material and FePO4 (Manufacturer: CNGR, purity: 99% or higher) as an iron phosphate raw material were each prepared in an anhydrous form. The above FePO4 was manufactured by the method described above.
[0232] 0.525 mol of the lithium raw material and 1 mol of the iron phosphate raw material were dry mixed for 1 hour using a dry powder mixer at 25 ℃.
[0233] The above dry mixture was mixed with purified water as a solvent for 2 hours to prepare a wet mixture in the form of a slurry. Here, the content of the dry mixture (solid content) was set to 30% by weight of the total weight of the wet mixture (100% by weight).
[0234] Glucose was added to the wet mixture in a reducing atmosphere. Here, the amount of glucose added was 8 parts by weight based on 100 parts by weight of the dry mixture (solid content).
[0235] The wet mixture with added glucose was wet-milled for 2 hours using a bead mill method with 0.3 mm beads, and the D50 particle size of the solid in the wet-milled material was made to reach 300 to 400 nm.
[0236] After measuring the viscosity of the above wet-ground material, spray drying was performed using a spray dryer with a moisture drying rate of 1 kg / hr, controlled at an input temperature of 200 to 300 ℃ and an output temperature of 100 to 120 ℃, while fixing the pumping speed at 50 rpm. The spray-dried material obtained here comprises D50 10 to 15 μm and D Max It was controlled to 40 μm or less.
[0237] The above spray-dried material was first calcined at 500°C for 2 hours, second calcined at 700°C for 10 hours, naturally cooled at room temperature, and then crushed and sieved to obtain an anode active material.
[0238] (3) Preparation of the anode
[0239] 95 wt% of the above positive active material, 1 wt% of Super-P and 0.6 wt% of CNT as conductive materials, and 2.5 wt% of HSV900 as a binder were uniformly mixed, and NMP was added as a solvent in an amount of 20 wt% relative to 100 wt% of the mixture and uniformly mixed, and then coated onto an aluminum foil (Al Foil) and dried to produce a positive electrode.
[0240] (4) Manufacturing of lithium secondary batteries
[0241] A coin cell of the 2016 standard was manufactured according to a conventional manufacturing process for lithium secondary batteries, using lithium metal as the counter electrode, the above positive electrode, and a porous polyethylene membrane as the separator. As the electrolyte, a liquid electrolyte was used in which 1.2 mol LiPF6 solute was added to a 1:1 (w:w) mixed solvent of EC (ethylene carbonate) and DEC (diethyl carbonate).
[0242]
[0243] Comparative Example 2
[0244] A positive electrode active material, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Comparative Example 1, except that NH3F was added as a flux along with purified water as a solvent at a content of 3% by weight relative to 100% by weight of the total solid content.
[0245]
[0246] Comparative Example 3
[0247] A positive electrode and a lithium secondary battery were manufactured in the same manner as Comparative Example 1, except that a positive electrode active material manufactured as follows was used.
[0248] Li2CO3 (manufacturer: Junsei, purity: 99% or higher) as a lithium raw material, Fe2O3 (manufacturer: Samjeon Sunyak, purity: 95% or higher) as an iron raw material, and NH4H2PO4 (manufacturer: Samjeon Sunyak, purity: 98% or higher) as a phosphorus raw material were each prepared in an anhydrous form.
[0249] At 25°C, 0.525 mol of the lithium raw material, 0.5 mol of the phosphorus raw material, and 1 mol of the phosphorus raw material were dry-mixed for 1 hour using a dry powder mixer. The lithium raw material was added in excess to account for the possibility of volatilization.
[0250] Ethanol was mixed with the dry mixture as a solvent for 2 hours to prepare a wet mixture in the form of a slurry. Here, the content of the dry mixture (solids) was set to 50% by weight of the total weight of the wet mixture (100% by weight).
[0251] Glucose was added to the wet mixture in a reducing atmosphere. Here, the amount of glucose added was 8 parts by weight based on 100 parts by weight of the dry mixture (solid content).
[0252] The wet mixture with added glucose was wet-milled for 2 hours using a bead mill method with 0.3 mm beads, and the D50 particle size of the solid in the wet-milled material was made to reach 300 to 400 nm.
[0253] After measuring the viscosity of the above wet-ground material, spray drying was performed using a spray dryer with a moisture drying rate of 1 kg / hr, controlled at an input temperature of 200 to 300 ℃ and an output temperature of 100 to 120 ℃, while fixing the pumping speed at 50 rpm. The spray-dried material obtained here comprises D50 10 to 15 μm and D MaxIt was controlled to 40 μm or less.
[0254] The above spray-dried material was first calcined at 500°C for 2 hours, second calcined at 700°C for 10 hours, naturally cooled at room temperature, and then crushed and sieved to obtain an anode active material.
[0255]
[0256] Example 1
[0257] A positive electrode and a lithium secondary battery were prepared in the same manner as Comparative Example 3, except that a wet mixture was prepared by mixing ethanol as a solvent with the dry mixture, and NH4F (manufacturer: Sigma-Aldrich, purity: 99%) was added as a flux at 0.5 wt% of the total solid content.
[0258]
[0259] Example 2
[0260] A positive electrode and a lithium secondary battery were prepared in the same manner as Comparative Example 3, except that a wet mixture was prepared by mixing ethanol as a solvent with the dry mixture, and NH4F (manufacturer: Sigma-Aldrich, purity: 99%) was added as a flux at 1.0 wt% of the total solid content.
[0261]
[0262] Example 3
[0263] A positive electrode and a lithium secondary battery were prepared in the same manner as Comparative Example 3, except that a wet mixture was prepared by mixing ethanol as a solvent with the dry mixture, and NH4F (manufacturer: Sigma-Aldrich, purity: 99%) was added as a flux at 2.0 wt% of the total solid content.
[0264]
[0265] Example 4
[0266] A positive electrode and a lithium secondary battery were prepared in the same manner as Comparative Example 3, except that a wet mixture was prepared by mixing ethanol as a solvent with the dry mixture, and NH4F (manufacturer: Sigma-Aldrich, purity: 99%) was added as a flux at 3.0 wt% of the total solid content.
[0267]
[0268] Example 5
[0269] A positive electrode and a lithium secondary battery were prepared in the same manner as Comparative Example 3, except that a wet mixture was prepared by mixing ethanol as a solvent with the dry mixture, and NH4F (manufacturer: Sigma-Aldrich, purity: 99%) was added as a flux at 5.0 wt% of the total solid content.
[0270]
[0271] Example 6
[0272] A positive electrode and a lithium secondary battery were prepared in the same manner as Comparative Example 3, except that a wet mixture was prepared by mixing ethanol as a solvent with the dry mixture, and NH4F (manufacturer: Sigma-Aldrich, purity: 99%) was added as a flux at 10.0 wt% of the total solid content.
[0273]
[0274] The types of raw materials used in Comparative Examples 1 to 3 above, whether a flux was used, and the amount used are summarized in Table 1 below. In Table 1 below, the amount of flux used refers to the content of the flux relative to 100 weight% of the total amount of solids containing the lithium raw material, the iron raw material, the phosphorus raw material, and the flux.
[0275]
[0276] Comparative Example 1: Li2CO3 and FePO4 - Comparative Example 2: Li2CO3 and FePO43 wt% - Comparative Example 3: Li2CO3, Fe2O3, and NH4H2PO4 - Example 1: Li2CO3, Fe2O3, and NH4H2PO4 0.5 wt% - Example 2: Li2CO3, Fe2O3, and NH4H2PO4 1 wt% - Example 3: Li2CO3, Fe2O3, and NH4H2PO4 2 wt% - Example 4: Li2CO3, Fe2O3, and NH4H2PO4 3 wt% - Example 5: Li2CO3, Fe2O3, and NH4H2PO4 5 wt% - Example 6: Li2CO3, Fe2O3, and NH4H2PO4 10 wt%
[0277] Evaluation Example 1: Cathode active material
[0278] (1) Grain size and impurity content
[0279] For the cathode active materials prepared in the comparative example and example, measurements were taken using an X-ray diffraction analyzer (trademark: Miniflex600, company name: Rigaku, Japan), and the 2θ value of the peak showing the maximum intensity and the corresponding intensity value were calculated. Then, these were applied to the JADE Software ICDD (International Centre for Diffraction Data) card to obtain the full width at half maximum and crystal information that can confirm the crystallinity of the synthesized active material using the lattice constants on the XRD and Rietveld analysis. Using this, the grain size calculation method (Scherrer equation) was applied to calculate the grain size and impurity content of the structure, and the results are listed in Table 2.
[0280] (2) Size of primary particles
[0281] For the cathode active materials prepared in the comparative example and example, the size of the primary particles was measured using SEM (emcraft, Genesis-2000), and the average of the particles was quantified in Table 2.
[0282] (3) Specific surface area
[0283] For the cathode active materials prepared in the comparative example and example, the specific surface area was measured using BET (Micromeritics, Tristar II 3020) and is listed in Table 2.
[0284] (4) Mathematical formulas 1 and 2
[0285] In addition, the grain size, primary grain size, and BET specific surface area obtained above were substituted into the aforementioned mathematical formulas 1 and 2, respectively, and quantified in Table 2.
[0286]
[0287] XYZ [Equation 1] Y / X [Equation 2] (Y / X)*Z Impurities (wt%) Grain size (nm) Primary particle size (nm) Surface area (m 2 / g)Li3PO4Fe2P2O7 Comparative Example 178.217512.172.23785227.23465-1.2 Comparative Example 295.53269.263.41361331.610051.1 Comparative Example 384.121710.242.58026226.421880.7 Example 180.922910.362.83065529.32559--Example 279.524110.993.03144733.3156--Example 378.631210.013.96946639.73435--Example 479.24169.535.25252550.05657--Example 582.94359.375.24728649.167070.60.3Example 693.65899.166.29273557.641451.20.9
[0288] Evaluation Example 2: Rolled density of the positive active material layer of a lithium secondary battery (1).
[0289] For the anodes prepared in the comparative example and example, the thickness at a total of four points was measured using a micrometer (Mitutoyo, 293-240-30), and the average of the rolling density was calculated and listed in Table 3.
[0290] (2) Mars capacity, lifetime, and rate-limit star output
[0291] For the lithium secondary batteries prepared in the comparative example and example, electrochemical characteristics were evaluated under the following conditions using an electrochemical analysis device (product name: WBCS3999K 32, manufacturer: Woori Engineering), and the results are listed in Table 3.
[0292] Formation Capacity: Performed 3 cycles of charging and discharging at 0.1 C in the voltage range of 2.0 V to 3.7 V (@ 25 ℃)
[0293] Life: Performed 100 cycles of charging and discharging at 1 C in the voltage range of 2.0 V to 3.7 V (@ 25 ℃)
[0294] Output by Rate Capacity: Discharge capacity verified from 0.1 C to 10 C in the voltage range of 2.0 V to 3.7 V (@ 25 ℃)
[0295]
[0296] Experiment Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Formation 1st Discharge 0.1C Capa. 155.28 7.214 7.6150.9154.9155.3155.6150.365.3 Eff. 96.98 3.28 9.79 2.596.69 7.29 7.98 8.67 2.7 Cycle Retention capacity(%) / 100 cycle(25°C) 92.4 64.5 91.3 93.2 94.5 98.6 99.9 62.7 53.1 C-rate 0.1 C 100% 100% 100% 100% 100% 100% 100% 100% 1 C 91.9% 57.2% 83.5% 84.1% 92.0% 92.6% 93.1% 54.6% 32.5% 5 C 73.5% 33.1% 61.2% 63.6% 73.4% 74.2% 74.7% 33.5% 11.1% 10 C 65.2% 14.5% 39.8% 44.3% 65.8% 66.3% 67.5% 16.2% 2.9% Anode Rolling Density Electrode Cross-section 25 mg / cm² 2 Standard (g / cm²) 3 )2.352.492.382.382.412.452.512.522.63
[0297] According to result tables 1 to 4, it can be seen that Comparative Examples 1 to 3 do not satisfy the above mathematical formulas or / or have an excessive amount of impurities, whereas Examples 1 to 6 satisfy the above mathematical formulas and can control the impurity content to an appropriate range.
[0298]
[0299] When comparing Comparative Examples 1 and 3 with changes in LFP synthesis raw materials, the amount of impurities that inevitably occur could not be controlled, and the grain size actually increased.
[0300] In addition, the specific surface area of the entire cathode active material decreased due to an increase in grain size and primary particle size, but the rolling density of the cathode did not increase significantly due to the excessive presence of impurities, and the overall electrochemical properties of the lithium secondary battery, such as capacity and lifespan, decreased.
[0301] As conventional iron phosphate raw materials are used without using flux, it is difficult to control the microstructure of the particles, and as each raw material combines individually during the reaction and is synthesized in a solid state while the reaction conditions are sensitive, the growth of crystal grains and the generation of impurities proceed excessively, which degrades the electrochemical performance of the lithium secondary battery.
[0302]
[0303] When comparing Comparative Examples 1 and 2 based on whether or not a flux was added, it can be seen that the primary particle size and specific surface area were controlled, but the crystal grain size was not controlled, resulting in a decrease in the capacity and output of the lithium secondary battery.
[0304]
[0305] Meanwhile, in Examples 1 to 6, in which a flux was added while changing the LFP synthesis raw material, it was confirmed that the rolling density of the anode was significantly improved, with the primary particles increasing by 1.3 to 1.8 times and the specific surface area decreasing while having the same level of crystal grain size as Comparative Example 1.
[0306] In addition, in Examples 1 to 6, as the primary particle size increased, the lifespan characteristics of the lithium secondary battery were improved, and as the generation of impurities was suppressed, the lithium secondary battery exhibited stable capacity and efficiency, and the output characteristics were also improved.
[0307] This is because the synthesis efficiency of the lithium salt is increased by adding an appropriate amount of flux, and the diffusion path of lithium ions is optimized by increasing the primary particle size while suppressing the excessive performance of the crystal grains and keeping them small.
[0308]
[0309] In summary, an embodiment represented by Examples 1 to 6 can provide an olivine or nasicon-based cathode active material in an environmentally friendly manner while controlling the size of the primary particles and the crystal grain size constituting them. Furthermore, by using the cathode active material according to an embodiment, high-performance cathodes and lithium secondary batteries can be provided in an environmentally friendly manner.
[0310]
[0311] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.
Claims
1. Aggregated with olivine or nasicon-based primary particles As a positive active material containing secondary particles; The above positive active material satisfies the following mathematical formula 1; The above positive electrode active material may or may not contain Fe2P2O7, and the content of Fe2P2O7 is 1 weight% or less relative to the total amount of 100 weight% of the above positive electrode active material. Cathode active material for lithium secondary batteries: [Mathematical Formula 1] 2.6 ≤ Y / X In the above mathematical formula 1, X is the grain size of the primary particle above; Y is the average particle size of the above primary particles.
2. In Paragraph 1, The above positive active material further satisfies the following mathematical formula 2, Cathode active material for lithium secondary batteries: [Mathematical Formula 2] 28 m 2 / g ≤ (Y / X)*Z In the above mathematical formula 2, The definitions of X and Y are the same as in Paragraph 1; Z is the specific surface area of the positive active material.
3. In Paragraph 1 or 2, The above X value is 78.5 to 95 nm, Cathode active material for lithium secondary batteries.
4. In Paragraph 1 or 2, The above Y value is 218 to 600 nm, Cathode active material for lithium secondary batteries.
5. In Paragraph 1 or 2, The above Z value is 9 to 12 m 2 / g person, Cathode active material for lithium secondary batteries.
6. In Paragraph 1, The above positive active material further comprises Li3PO4; The content of the Li3PO4 is 1.2 weight% or less relative to the total amount of 100 weight% of the above positive active material, Cathode active material for lithium secondary batteries.
7. In Paragraph 1, The above primary particle is represented by the following chemical formula 1, Cathode active material for lithium secondary batteries: [Chemical Formula 1] Li a Fe x M y PO 4-b X b In the above chemical formula 1, 0.9≤a≤1.1, 0.1≤x≤1, 0≤y≤0.9, and 0≤b≤0.1, and M is one or more elements selected from the group consisting of Al, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Ti, V, Zn, Nb, and Zr, and X is one or more elements selected from the group consisting of F and Cl.
8. A step of dry mixing lithium raw materials, iron raw materials, and phosphorus raw materials; A step of adding a solvent to the above dry mixture and wet mixing; A step of grinding the above wet mixture; A step of spray-drying the above wet ground material; and The step of firing the above spray-dried product is included, Introducing a flux together with the solvent during the above wet mixing, Method for manufacturing a positive electrode active material for a lithium secondary battery.
9. In Paragraph 8, The above flux is a non-metallic fluoride, Method for manufacturing a positive electrode active material for a lithium secondary battery.
10. In Paragraph 9, The above flux is NH3F, Method for manufacturing a positive electrode active material for a lithium secondary battery.
11. In any one of paragraphs 7 through 10, A mixture in which the content of the flux is greater than 0 weight% and less than or equal to 10 weight% of the total amount of solids comprising the lithium raw material, the iron raw material, the phosphorus raw material, and the flux. Method for manufacturing a positive electrode active material for a lithium secondary battery.
12. In any one of paragraphs 7 through 10, The above lithium raw material is any one compound selected from the group consisting of lithium oxides, hydroxides, nitrates, carbonates, acetates, and mixtures thereof. Method for manufacturing a positive electrode active material for a lithium secondary battery.
13. In any one of paragraphs 7 through 10, The above iron raw material is any one compound selected from the group consisting of iron oxides, hydroxides, nitrates, carbonates, and mixtures thereof, Method for manufacturing a positive electrode active material for a lithium secondary battery.
14. In any one of paragraphs 7 through 10, The above phosphorus raw material is any one compound selected from the group consisting of phosphorus oxides, hydroxides, nitrates, carbonates, ammonium mixed salts, hydrogen mixed salts, and mixtures thereof. Method for manufacturing a positive electrode active material for a lithium secondary battery.
15. In any one of paragraphs 7 through 10, The above lithium raw material, iron raw material, and phosphorus raw material satisfy the stoichiometric molar ratio represented by the following chemical formula 1, Method for manufacturing a positive electrode active material for a lithium secondary battery: [Chemical Formula 1] Li a Fe x M y PO 4-b X b In the above chemical formula 1, 0.9≤a≤1.1, 0.1≤x≤1, 0≤y≤0.9, and 0≤b≤0.1, and M is one or more elements selected from the group consisting of Al, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Ti, V, Zn, Nb, and Zr, and X is one or more elements selected from the group consisting of F and Cl.
16. In any one of paragraphs 7 through 10, The above solvent is ethanol, Method for manufacturing a positive electrode active material for a lithium secondary battery.
17. In any one of paragraphs 7 through 10, The above dry mixture further comprises carbon raw materials, Method for manufacturing a positive electrode active material for a lithium secondary battery.
18. Positive current collector; and A positive active material layer comprising a positive active material of claim 1, positioned on the positive current collector, Cathode for lithium secondary batteries.
19. In Paragraph 18, The above positive active material layer is 25 mg / cm² on one surface of the positive current collector. 2 When loading, The rolled density of the above positive active material layer is 2.38 g / cm³ 3 person, Cathode for lithium secondary batteries.
20. A lithium secondary battery comprising the positive electrode of claim 18; a negative electrode; and an electrolyte.