Positive electrode active material preparation method, positive electrode active material, positive electrode, and lithium secondary battery

Abstract

A positive electrode active material of the present disclosure comprises: a core comprising lithium transition metal oxide particles having an olivine-type crystal structure; a carbon coating layer disposed on at least one portion of the surface of the core; and a metalloid coating layer disposed on at least one portion of the surface of the carbon coating layer. The lithium transition metal oxide comprises manganese. The metalloid coating layer comprises: a metalloid compound having one or both metalloid elements selected from the group consisting of silicon (Si) and boron (B); and a Li-M-O complex compound (where M is the metalloid element).

Description

Method for manufacturing a positive electrode active material, positive electrode active material, positive electrode and lithium secondary battery

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0037607 filed on March 24, 2025, and Korean Patent Application No. 10-2026-0050666 filed on March 20, 2026.

[0002] The present application relates to a method for manufacturing a positive electrode active material, a positive electrode active material, a positive electrode, and a lithium secondary battery according to the present invention.

[0003] Recently, lithium-ion batteries are being widely applied not only to small devices such as portable electronic equipment, but also to medium and large-sized devices such as battery packs or power storage systems for hybrid and electric vehicles. In particular, with the growing concern for environmental issues, extensive research is being conducted on electric vehicles and hybrid electric vehicles that can replace fossil fuel-using vehicles, such as gasoline and diesel cars, which are a major cause of air pollution.

[0004] Generally, a lithium secondary battery is an electrical device in which an electrode assembly consisting of a positive electrode, a negative electrode, and a separator is impregnated with a lithium electrolyte. The positive electrode includes a lithium transition metal oxide capable of reversibly inserting or extracting lithium as an active material. Lithium transition metal oxides can be classified into materials having a layered crystal structure such as lithium cobalt oxide, ternary materials such as lithium nickel-cobalt-manganese oxide, materials having a spinel crystal structure such as lithium manganese oxide, and materials having an olivine-type crystal structure such as lithium iron phosphate.

[0005] Lithium transition metal oxides having a double olivine-type crystal structure have the advantages of being inexpensive and highly safe. However, the aforementioned active material has the disadvantage of low energy density. Accordingly, to increase the energy density of lithium transition metal oxides having an olivine-type crystal structure, a cathode active material having a structure in which a portion of the metal is substituted with manganese has been developed. However, lithium transition metal oxides with a manganese-substituted olivine-type crystal structure have a problem of degraded output characteristics.

[0006]

[0007] The problem that the technical concept of the present invention aims to solve is to improve the output characteristics of a lithium transition metal oxide with a manganese-substituted olivine-type crystal structure.

[0008] The present invention aims to provide a cathode and a lithium secondary battery that improve high-rate charge / discharge performance without lowering the proportion of manganese in the cathode active material, thereby achieving high energy density while having excellent high-rate charge / discharge performance.

[0009] In addition, the present invention aims to improve the capacity expression of the anode active material.

[0010]

[0011] A positive electrode active material according to exemplary embodiments of the present invention comprises a core comprising lithium transition metal oxide particles having an olivine-type crystal structure; a carbon coating layer disposed on at least a portion of the surface of the core; and a metalloid coating layer disposed on at least a portion of the surface of the carbon coating layer, wherein the lithium transition metal oxide comprises manganese, and the metalloid coating layer may comprise a metalloid compound having one or two metalloid elements selected from the group consisting of silicon (Si) and boron (B); and a Li-MO composite compound (wherein M is the metalloid element).

[0012] The above Li-MO composite compound may also be present at the interface between the carbon coating layer and the metalloid coating layer.

[0013] When analyzing the depth profile by ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry), the intensity of the Li-MO composite compound increases in the sputtering time range of Os to 100 s, and I, which is the average intensity of the Li-MO composite compound in the sputtering time range of 200 s to 800 s, is 200~800 I, which is the average intensity of the Li-MO composite compound in the sputtering time range of 0s to 100s. 0~100 It can be maintained at a higher level.

[0014] The metalloid compound above may be represented by any one of the following chemical formulas 1 to 3.

[0015] [Chemical Formula 1]

[0016] SiO P

[0017] In the above chemical formula 1, 0≤p≤2.

[0018] [Chemical Formula 2]

[0019] B q O r

[0020] In the above chemical formula 2, 0≤q≤3 and 0≤r≤3.

[0021] [Chemical Formula 3]

[0022] Above B q O r ·SiO P

[0023] In chemical formula 3, 0≤p≤2, 0≤q≤3, and 0≤r≤3.

[0024] The above lithium transition metal oxide may include a compound represented by the following chemical formula 4.

[0025] [Chemical Formula 4]

[0026] Li 1+a Mn 1-b-c Fe b M 2c PO4

[0027] In the above chemical formula 4,

[0028] M 2 is one or more of Ti, V, Zr, Sr, Sb, Co, Ni, Mg, Na, and Nb, and

[0029] a, b, and c are -0.5≤a≤0.5, 0.05≤b≤0.8, and 0≤c≤0.2.

[0030] The above-mentioned cathode active material is SiO2 measured in ToF-SIMS analysis. - The integral strength of (I SiO2 Li2SiO for ) - The integral strength of (I Li2SiO The ratio value of ) (I Li2SiO / I SiO2 ) can be 1.0 or higher.

[0031] The above-mentioned cathode active material is Li2SiO2 measured in ToF-SIMS analysis. - The integral strength of (I Li2SiO The value of ) may be in the range of 0.1 to 1.0.

[0032] The metalloid compound is one selected from the compounds represented by Chemical Formula 2 and Chemical Formula 3, and in the Li-MO complex compound, M may be boron.

[0033] The anode according to exemplary embodiments of the present invention comprises the anode active material.

[0034] A lithium secondary battery according to exemplary embodiments of the present invention comprises a positive electrode; a negative electrode; an electrolyte; and a separator, wherein the positive electrode comprises the positive electrode active material.

[0035] A method for manufacturing an anode active material according to exemplary embodiments of the present invention comprises: a mixing step of mixing a lithium transition metal oxide having an olivine-type crystal structure into a dispersion solution containing a metalloid source; a drying step of drying the mixture; and a heat treatment step, wherein the lithium transition metal oxide has a carbon coating layer.

[0036] The carbon coating layer can be disposed on at least a portion of the lithium transition metal oxide surface.

[0037] The metalloid source may be one or more mixtures selected from the group consisting of tetraethyl orthosilicate [Si(OC2H5)4], lithium metaborate (LiBO2), boron oxide (B2O3), and trimethylsiloxyboron ([B(OSiCH3)3]).

[0038] In the above mixing step, the concentration of the metalloid source in the dispersion solution may be in the range of 0.01 to 0.9 weight percent.

[0039] In the above mixing step, the weight ratio of the metalloid source and the lithium transition metal oxide having an olivine-type crystal structure may be 1:10 to 1:1000.

[0040] The above heat treatment step can be performed under an inert atmosphere.

[0041] In the above heat treatment step, the heat treatment temperature may be in the range of 400 to 700℃.

[0042] In the above heat treatment step, the heat treatment time may be in the range of 1 to 10 hours.

[0043] The positive electrode active material according to exemplary embodiments of the present invention has excellent energy density as some metals are substituted with manganese, and exhibits excellent high-rate charge / discharge performance as a result of suppressing the generation of LiF at the positive electrode-electrolyte interface and reducing interfacial impedance.

[0044] The cathode active material according to exemplary embodiments of the present invention has a Li-MO composite compound present on its surface that enhances the mobility of lithium ions, thereby enabling the capacity development rate to be improved while maintaining stable output performance.

[0045] The cathode active material according to exemplary embodiments of the present invention suppresses the generation of LiF at the interface, thereby maintaining the structural stability of the manganese-rich olivine-structured lithium transition metal oxide even under high-speed charging conditions, and enables the realization of a lithium secondary battery with excellent capacity and cycle characteristics.

[0046] FIG. 1 is a flowchart for explaining a method for manufacturing a positive electrode active material according to exemplary embodiments.

[0047] FIG. 2 shows Si by ToF-SIMS of the cathode active materials of Example 1 and Comparative Example 3. - It is the depth profile.

[0048] Figure 3 shows the SiO2 of the cathode active materials of Example 1 and Comparative Example 3 by ToF-SIMS. - It is the depth profile.

[0049] Figure 4 is the depth profile of the fragments detected during ToF-SIMS analysis of the positive electrode active material of Example 1.

[0050] Figure 5 is the depth profile of the fragments detected during ToF-SIMS analysis of the positive electrode active material of Comparative Example 3.

[0051] Figure 6 is a graph showing the individual integrated intensities of fragments measured during ToF-SIMS analysis of the cathode active materials of Example 1 and Comparative Example 3.

[0052] FIG. 7 shows the LiF obtained by ToF-SIMS analysis of anode samples obtained from batteries containing each anode active material of Example 1 and Comparative Example 3. - This is an image of the 3D mapping of the distribution.

[0053] FIG. 8 shows the results of ToF-SIMS analysis of anode samples obtained from batteries containing each anode active material of Example 1 and Comparative Example 3, F - This is a graph showing the integral strength values ​​of each species.

[0054] Figure 9 shows the impedance data of a coin-type battery cell containing the positive active material of Example 1 and the impedance data of a coin-type battery cell containing the positive active material of Comparative Example 3.

[0055] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0056] The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0057] In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0058] In this specification, the term “combination(s) thereof” included in the surface of the Markush type means one or more mixtures or combinations selected from the group consisting of components described in the representation of the Markush type, and means including one or more selected from the group consisting of said components.

[0059] In this specification, the description “A and / or B” means “A or B or both.”

[0060] In this specification, D 50 represents the particle size at the 50% point of the cumulative volume distribution according to particle size. The above D 50 It can be measured in a manner commonly applied in the industry. For example, the above D 50 It can be measured using a particle size analyzer or an analytical instrument utilizing the laser diffraction scattering particle size distribution method, and by calculating the cumulative volume distribution according to particle size and calculating the particle diameter at the point where the cumulative volume distribution according to particle size in the measuring device is 50%, D 50 This can be measured.

[0061] In this specification, "ToF-SIMS (Time of Flight secondary Ion Mass Spectrometry) analysis" was performed in cation detection mode and anion detection mode. Depth profiling was Cs + Sputtering beam and Bi3 + It was performed using an analysis beam, and 3D imaging was obtained through sequential sputtering and signal accumulation. All measurements were performed under ultra-high vacuum conditions.

[0062]

[0063] The present invention will be described in more detail below.

[0064]

[0065] positive electrode active material

[0066] A positive electrode active material according to exemplary embodiments comprises: a core comprising lithium transition metal oxide particles having an olivine-type crystal structure; a carbon coating layer disposed on at least a portion of the surface of the core; and a metalloid coating layer disposed on at least a portion of the surface of the carbon coating layer.

[0067] The above lithium transition metal oxide may contain manganese. The above lithium transition metal oxide may be one in which a portion of the transition metal is substituted with manganese. A lithium transition metal oxide containing manganese (hereinafter referred to as "LMFP") has a higher energy density compared to a lithium transition metal oxide that does not contain manganese.

[0068] LMFP cathodes with high manganese content are promising cathode materials for next-generation lithium secondary batteries due to their high capacity, but they suffer from severe performance degradation under industrially important high-load conditions, particularly during high-rate charge-discharge. The inventors of the present invention suggest that the kinetic limiting factor of high-load LFMP cathodes is charge transfer resistance (R) at the cathode-electrolyte interface, rather than bulk lithium ion diffusion performance. ct It was discovered that the accumulation of electrically insulating LiF at the interface (CEI) between the LMFP anode and the electrolyte is the main cause of slow charge transfer. Based on these research results, it was discovered that suppressing the accumulation of LiF at the anode-electrolyte interface is important to improve high-rate charge / discharge performance in manganese-containing LMFP anodes, leading to the present invention.

[0069] As one of the methods for suppressing the accumulation of LiF at the anode-electrolyte interface, the present invention provides surface modification. The surface modification may involve forming a metalloid coating layer on the surface of the LMFP. The metalloid coating layer may comprise a metalloid compound having one or two metalloid elements selected from the group consisting of silicon (Si) and boron (B); and a Li-MO composite compound (wherein M is the metalloid element).

[0070] Since the metalloid compound and Li-MO composite compound act as Lewis acids to suppress the manganese leaching reaction caused by HF, the metalloid coating layer can serve as a protective layer. The leached manganese from the LMFP can decompose the electrolyte and accelerate the generation of HF, and the generated HF can again leach manganese, and LiF, a resistive component, can be fixed in the place of the leached manganese. However, since the metalloid compound and Li-MO composite compound suppress the manganese leaching reaction, the cathode active material of the present invention can fundamentally block the series of reactions described above.

[0071] In exemplary embodiments, the metalloid compound may be a compound represented by any one of the following chemical formulas 1 to 3.

[0072] [Chemical Formula 1]

[0073] SiO P

[0074] In the above chemical formula 1, 0≤p≤2.

[0075] [Chemical Formula 2]

[0076] B q O r

[0077] In the above chemical formula 2, 0≤q≤3 and 0≤r≤3.

[0078] [Chemical Formula 3]

[0079] Above B q O r ·SiO P

[0080] In chemical formula 3, 0≤p≤2, 0≤q≤3, and 0≤r≤3.

[0081] The metalloid compound mentioned above may be, for example, Si, SiO, SiO2, Si2O3, B, BO, BO2, B2O3, B2O3-SiO, B2O3-SiO2, B2O3-Si2O3, etc. However, the metalloid compound is not limited to these.

[0082] The above Li-MO composite compound may refer to a multicomponent compound comprising lithium, M (where M is silicon and / or boron), and oxygen. The above Li-MO composite compound may have a crystalline, amorphous, or mixed form. If M is silicon (Si), it may include Li2SiO or a non-stoichiometric compound thereof. If M is boron (B), it may include LiBO2 or a non-stoichiometric compound thereof.

[0083] In exemplary embodiments, the Li-MO composite compound may exist not only in the metalloid coating layer but also at the interface between the carbon coating layer and the metalloid coating layer. The Li-MO composite compound is a compound in which lithium is complexed with a metalloid compound; in this specification, it will be referred to as a Li-MO composite compound to distinguish it from the metalloid compound. The Li-MO composite compound formed at the above location physically suppresses the leaching of manganese by blocking the path through which the electrolyte approaches the vicinity of the core, and even if manganese is partially leached, the Li-MO composite compound can chemically capture the leached manganese ions to slow down the rate of manganese leaching. Since the Li-MO composite compound contains lithium, it can act as a channel for lithium ions to enter and exit, thereby improving the mobility performance of lithium ions. Additionally, the Li-MO composite compound acts as a sieve that prevents manganese ions from passing through, thereby suppressing the formation of LiF. Accordingly, the cathode active material of the present invention can realize a lithium secondary battery with excellent charge output and high-rate charge / discharge performance.

[0084] In exemplary embodiments, when analyzing the depth profile by Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), the intensity of the Li-MO composite compound increases in the sputtering time range of Os to 100 s, and I, which is the average intensity of the Li-MO composite compound, is in the sputtering time range of 200 s to 800 s. 200~800 I, which is the average intensity of the Li-MO composite compound in the sputtering time range of 0s to 100s. 0~100 It can be maintained at a higher level. This characteristic is manifested by the distribution characteristics of the above-mentioned Li-MO composite compound. The distribution characteristics of the above-mentioned Li-MO composite compound impart robustness to the coating layer of the anode active material of the present invention.

[0085] Figure 4 illustrates the depth profile by ToF-SIMS of the cathode active material obtained by surface modification according to Example 1, and Figure 5 illustrates the depth profile of the cathode active material not surface modified according to Comparative Example 3. In these figures, the x-axis represents the sputtering time, and the y-axis represents the Li-MO composite compound, Li2SiO2 - It indicates the strength of.

[0086] Referring to Fig. 4, as the sputtering time increases, Li2SiO - It shows a tendency to increase in strength, and when it reaches a certain strength, Li2SiO - It can be confirmed that the strength of is maintained at a constant level. Here, being maintained at a constant level means that Li2SiO - There is no change in the strength of, or Li2SiO - This means that the change in intensity is very small. Specifically, Li2SiO in the sputtering time range of Os to 100s -The intensity increases, and Li2SiO in the sputtering time range of 200s to 800s - I, the average intensity of 200~800 I, the average intensity of the Li-MO composite compound in the sputtering time range of 0s to 100s. 0~100 It is maintained at a higher level.

[0087] The depth profile obtained by ToF-SIMS is the result of analyzing the composition as it etches from the surface inward over time. Since the sputtering time on the x-axis represents the time it takes for the ion beam to etch the sample surface, a value closer to 0 indicates the outermost surface, and as time passes (increasing time), it signifies penetration into the interior (depth) of the sample. Furthermore, "Normalized Intensity" on the y-axis represents the specific ion fragment (Li2SiO2) detected. - It indicates the amount of ). The higher the intensity value, the more of that component is present at that location.

[0088] Interpreting FIG. 4 accordingly, in the positive electrode active material according to the embodiment, Li2SiO - It exists along the direction from the particle surface toward the interior, but the closer to the interior, the more Li2SiO - The amount of will increase. That is, in the cathode active material according to the exemplary embodiments of the present invention, the Li-MO composite compound can be distributed in larger quantities as it moves further away from the outermost part of the active material. This specific distribution of the Li-MO composite compound can effectively suppress the formation of LiF by providing robustness to the interface between the carbon coating layer and the metalloid coating layer and to the metalloid coating layer.

[0089] In exemplary embodiments, the metalloid may be silicon. In this case, the anode active material is SiO2 as measured in ToF-SIMS analysis. - The integral strength of (I SiO2 Li2SiO for ) - The integral strength of (ILi2SiO The ratio value of ) (I Li2SiO / I SiO2 ) may be 1.0 or higher, preferably in the range of 1.1 to 5, and more preferably 1.5 to 4. In exemplary embodiments, the cathode active material is Li2SiO measured in ToF-SIMS analysis - The integral strength of (I Li2SiO The value of ) may be in the range of 0.1 to 1.0, more specifically 0.15 to 0.8, and even more specifically 0.2 to 0.7. This means that the weight ratio of the Li-Si-O composite compound among the compounds generated through surface modification is relatively high. Compared to the surface-modified LMFP, the cathode active material of the present invention is rich in the Li-Si-O composite compound. Accordingly, the cathode active material of the present invention can further stabilize the interface between the cathode and the electrolyte, and can realize a lithium secondary battery with improved electrochemical performance due to excellent lithium ion transport characteristics.

[0090] In exemplary embodiments, the metalloid compound may be one selected from the compounds represented by Formula 2 and Formula 3. In this case, M in the Li-MO composite compound is boron. When the metalloid is boron, compared to when the metalloid is silicon, the mobility of lithium ions is superior and the effect of inhibiting manganese leaching may be better.

[0091] In exemplary embodiments, the lithium transition metal oxide of the core may include a compound represented by the following chemical formula 4.

[0092] [Chemical Formula 4]

[0093] Li 1+a Mn 1-b-c Fe b M 2 c PO4

[0094] In the above chemical formula 3,

[0095] M2 is one or more of Ti, V, Zr, Sr, Sb, Co, Ni, Mg, Na, and Nb, and

[0096] a, b, and c are -0.5≤a≤0.5, 0.05≤b≤0.8, and 0≤c≤0.2.

[0097] The compound represented by the above chemical formula 4 has an olivine-type crystal structure. The olivine-type crystal structure has a hexahedral crystal structure in which phosphorus (P) and oxygen (O) are strongly bonded, resulting in high structural stability. Furthermore, when manganese is substituted, it has the advantage of superior energy density compared to the case where manganese is not substituted. And, the above M 2 When metals such as [material] are doped or substituted, there is an advantage in that the rolling density can be improved.

[0098] Among the compounds represented by the above chemical formula 4, LiMn 0.8 Fe 0.2 PO4, LiMn 0.6 Fe 0.39 Ti 0.01 PO4, LiMn 0.7 Fe 0.3 PO4, LiMn 0.6 Fe 0.4 PO4, LiMn 0.5 Fe 0.5 PO4, LiMn 0.4 Fe 0.6 PO4, LiMn 0.3 Fe 0.7 PO4, LiMn 0.8 Fe 0.19 Ti 0.01 PO4, LiMn 0.7 Fe 0.29 Ti 0.01 PO4, LiMn 0.6 Fe 0.39 Ti 0.01 PO4, LiMn 0.8 Fe 0.17 Ti 0.03 PO4, LiMn 0.7 Fe 0.27 Ti 0.03 PO4, LiMn 0.6 Fe 0.37 Ti0.03 PO4, LiMn 0.8 Fe 0.15 You 0.05 PO4, LiMn 0.7 Fe 0.25 You 0.05 PO4, LiMn 0.6 Fe 0.35 You 0.05 PO4, LiMn 0.8 Fe 0.18 You 0.01 V 0.01 PO4, LiMn 0.7 Fe 0.28 You 0.01 V 0.01 PO4, LiMn 0.6 Fe 0.38 You 0.01 V 0.01 PO4, LiMn 0.8 Fe 0.15 You 0.025 V 0.025 PO4, LiMn 0.7 Fe 0.25 You 0.025 V 0.025 PO4, LiMn 0.6 Fe 0.35 You 0.025 V 0.025 PO4, LiMn 0.8 Fe 0.1 You 0.05 V 0ㄹ ] LiMn 0.8 Fe 0.12 You 0.03 Zr 0.025 Nb 0.025 PO4, LiMn 0.7 Fe 0.22 You 0.03 Zr 0.025 Nb 0.025 PO4, LiMn 0.6 Fe 0.32 You 0.03 Zr 0.025 Nb 0.025 PO4, LiMn 0.8 Fe 0.05 You 0.05 Zr 0.05 Nb 0.05 PO4, LiMn 0.7 Fe 0.15 You0.05 Zr 0.05 Nb 0.05 PO4, LiMn 0.6 Fe 0.25 Ti 0.05 Zr 0.05 Nb 0.05 Examples include PO4, but are not limited to these.

[0099] In exemplary embodiments, the lithium transition metal oxide comprises manganese and iron, and the molar ratio of manganese to iron may be in the range of 8:2 to 2:8, more specifically 75:25 to 25:75, and even more specifically 7:3 to 3:7. The cathode active material according to the present invention has an excellent capacity development rate and excellent high-rate charge / discharge performance even when the proportion of manganese is high.

[0100] In exemplary embodiments, the lithium transition metal oxide has an average particle size D 50 This may be 1.0㎛ or less. Specifically, it may be 0.05㎛ or more, 0.1㎛ or more, 0.15㎛ or more, 0.2㎛ or more, or 0.25㎛ or more, and may be 1.0㎛ or less, 0.95㎛ or less, 0.90㎛ or less, 0.85㎛ or less, or 0.80㎛ or less, and preferably may be in the range of 0.2㎛ to 0.8㎛. Satisfying the above range is desirable in that it enables the realization of a high-density electrode, while also facilitating the increase of slurry solid content during electrode fabrication, thereby enabling the realization of excellent energy density and processability, and excellent discharge capacity.

[0101] In exemplary embodiments, the lithium transition metal oxide has a BET specific surface area of ​​1 m² 2 / g to 30m 2 It can be / g, preferably 2m 2 / g to 25m 2 It can be / g, and more preferably 5m 2 / g to 20m 2It may be / g. If the above range is satisfied, it may be advantageous in terms of making it easier to increase the slurry solid content during electrode fabrication and having excellent electrolyte impregnation properties.

[0102] The carbon coating layer may be disposed along a portion of the surface of a core containing lithium transition metal oxide particles having an olivine-type crystal structure, or may cover the entire surface of the core. The carbon coating layer improves the electrical conductivity and structural stability of the lithium transition metal oxide.

[0103] In exemplary embodiments, the weight of the carbon coating layer may be 0.5% to 5.0% by weight based on the total weight of the positive electrode active material, preferably 0.8% to 4.0% by weight, and more preferably 1.0% to 3.0% by weight. Satisfying the above range may be desirable in that it improves the electronic conductivity of the positive electrode active material without acting as a resistor.

[0104] In exemplary embodiments, the thickness of the carbon coating layer may be in the range of 0.1 nm to 5 µm, 0.5 nm to 5 µm, 1 nm to 5 µm, 1 nm to 1 µm, 1 nm to 500 nm, 1 nm to 200 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 20 nm. As the carbon coating layer has a thickness within the above range, the electronic conductivity of the positive active material may be further improved and the internal resistance may be further reduced.

[0105] In exemplary embodiments, the Li-MO composite compound may also be present in the carbon coating layer. Since the surface of the carbon coating layer contains pores, some of the metalloids derived from the metalloid source may penetrate into the pores on the surface of the carbon coating layer and form the Li-MO composite compound through a chemical reaction. While all or a substantial amount of the Li-MO composite compound is formed on the surface of the cathode active material, for this reason, some of the Li-MO composite compound may be present in the carbon coating layer.

[0106] In exemplary embodiments, the positive electrode active material may further comprise a Li-MC composite compound. The Li-MC composite compound is a material produced by a chemical reaction between lithium remaining on the surface of the core particle during the formation of the metalloid coating layer, the carbon component of the carbon coating layer, and a metalloid. The positive electrode active material of the present invention can improve rapid charge / discharge performance by including a larger amount of the Li-MC composite compound compared to an unsurface-modified LMFP. Specifically, the Li-MC composite compound may be LiSiC2 or LiB2C.

[0107] In exemplary embodiments, the metalloid coating layer may be disposed on the carbon coating layer. The metalloid compound may be formed on the surface of the carbon coating layer and in the pores on the surface of the carbon coating layer. An anode active material with such a structure has a core-carbon coating layer-metalloid coating layer structure. This double-shell structure enables excellent control of the interfacial reaction between the anode active material and the electrolyte.

[0108] In exemplary embodiments, the metalloid compound is present in an amount of 0.001–3 wt%, 0.002–3 wt%, 0.005–2.5 wt%, 0.01–2.5 wt%, 0.01–2.0 wt%, 0.03–2.5 wt%, 0.03–2.0 wt%, 0.05–2.5 wt%, 0.05–2.3 wt%, 0.05–2.0 wt%, 0.1–2.0 wt%, 0.1–1.5 wt%, 0.15–2.0 wt%, 0.15–1.5 wt%, 0.2–2.0 wt%, 0.2–1.5 wt%, 0.3–2.0 wt%, 0.3–1.5 wt%, based on the total weight of the anode active material. The range may be 0.3~1.0wt%, 0.5~2.0wt%, 0.5~1.5wt%, or 0.5~1.0wt%. When the metalloid oxide is included in the above content, high-rate charge / discharge characteristics are improved, and the capacity development rate of the positive electrode active material is excellent.

[0109] In exemplary embodiments, the Li-MO composite compound is present in an amount of 0.001–5 wt%, 0.002–4.5 wt%, 0.005–4.0 wt%, 0.01–3.5 wt%, 0.01–3.0 wt%, 0.03–2.5 wt%, 0.05–5.0 wt%, 0.1–4.5 wt%, 0.1–4.0 wt%, 0.1–3.5 wt%, 0.2–4.0 wt%, 0.2–3.0 wt%, 0.3–4.0 wt%, 0.3–3.0 wt%, 0.4–4.0 wt%, 0.4–3.0 wt%, 0.5–2.0 wt%, 0.5–3.0 wt%, based on the total weight of the cathode active material. The range may be 0.5~2.0wt%, 1.0~4.0wt%, 1~3.0wt%, or 1~2.0wt%. When the above Li-MO composite compound is included in the above content, high-rate charge / discharge characteristics are improved, and the capacity development rate of the positive electrode active material is excellent.

[0110] In exemplary embodiments, the particle size of the metalloid compound may be in the range of 0.01 to 100 nm, 0.5 to 100 nm, 1 to 100 nm, 1 to 50 nm, 1 to 30 nm, 5 to 50 nm, 5 to 30 nm, and 10 to 30 nm. Here, the particle size is based on the major axis length of the metalloid compound particle. As the metalloid compound has a particle size in the nano range, the metalloid compound can be uniformly distributed on the surface of the positive electrode active material.

[0111] In exemplary embodiments, the particle size of the Li-MO composite compound may be in the range of 0.01 to 200 nm, 0.5 to 150 nm, 1 to 100 nm, 1 to 50 nm, 1 to 30 nm, 5 to 50 nm, 5 to 30 nm, and 10 to 30 nm. Here, the particle size is based on the major axis length of the Li-MO composite compound particle.

[0112] According to exemplary embodiments of the present invention, even if the manganese content of the cathode active material is high, the aforementioned metalloid coating layer suppresses LiF generation at the cathode-electrolyte interface, thereby enabling the realization of a lithium secondary battery with excellent high-rate charge / discharge performance. Furthermore, the cathode active material of the present invention improves the mobility of lithium ions, resulting in an improved capacity development rate, which enables the realization of a lithium secondary battery with high energy density.

[0113]

[0114] anode

[0115] The anode according to exemplary embodiments of the present invention comprises the anode active material. Since the anode active material has been described in detail above, a redundant description will be omitted.

[0116] In exemplary embodiments, the anode may comprise an anode current collector; and an anode active material layer disposed on at least one surface of the anode current collector. The anode active material layer may comprise an anode active material and additionally may further comprise one or more of a binder, a conductive material, and a dispersant.

[0117] The above-mentioned positive active material may be included in a range of 90 to 98 weight%, specifically 93 to 98 weight%, and even more specifically 95 to 97.5 weight%, based on the total weight of the positive active material layer. When the content of the positive active material is within the above range, a positive active material with excellent thermal and chemical stability is included as a main component, thereby enabling the realization of a battery with excellent safety. The high content of the positive active material is advantageous for capacity expression relative to volume, allowing for the realization of a lithium secondary battery with high energy density. In particular, the positive electrode containing the positive active material of the present invention can realize a high-loading positive electrode even when the positive active material is contained in 95 weight% or more, as the kinetic performance of manganese is improved.

[0118] The above binder is a component that assists in the bonding of the positive active material and the conductive material, and the bonding to the current collector, and may be included in an appropriate amount within a range that does not degrade the electrical properties of the positive electrode. Specifically, the binder may be one or more mixtures selected from the group consisting of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride (PVdF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene butadiene rubber (SBR), and fluororubber.

[0119] The content of the binder may be in the range of 0.1 to 10 weight%, specifically 0.5 to 8 weight%, and more specifically 0.5 to 5.0 weight% based on the total weight of the positive active material layer. By controlling the content of the binder contained in the positive active material layer to the above range, the present invention can prevent the adhesion of the positive active material layer from being reduced due to a low content of binder or the electrical properties of the positive electrode from being reduced due to an excessive amount of binder.

[0120] The above conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0121] The content of the conductive material may be in the range of 0.1 to 10 wt%, specifically 0.5 to 8 wt%, and more specifically 0.5 to 5.0 wt%. By controlling the content of the conductive material to the above range, the present invention can prevent the decrease in charging capacity caused by an increase in electrode resistance due to a low content of conductive material, and can prevent problems such as a decrease in charging capacity caused by a reduction in the content of the cathode active material introduced due to an excessive amount of conductive material, or a decrease in rapid charging characteristics due to an increase in the loading amount of the cathode active material layer.

[0122] The above-mentioned positive active material layer may further include a dispersant to improve the dispersibility of the positive active material. The dispersant may include hydrogenated nitrile butadiene rubber. Hydrogenated nitrile butadiene rubber refers to nitrile butadiene rubber that has undergone a hydrogenation reaction to convert the double bonds originally contained in the nitrile butadiene rubber into single bonds.

[0123] The above hydrogenated nitrile butadiene rubber may have a repeating unit content derived from acrylonitrile (AN) of 20% to 50% by weight relative to the total weight, more preferably 25% to 45% by weight, and most preferably 30% to 40% by weight.

[0124] The weight-average molecular weight (Mw) of the hydrogenated nitrile butadiene rubber may be in the range of 10,000 g / mol to 100,000 g / mol, more specifically 10,000 g / mol to 50,000 g / mol, and even more specifically 15,000 to 40,000 g / mol. When the weight-average molecular weight (Mw) of the hydrogenated nitrile butadiene rubber is in the above range, the aggregation of the anode active material particles of the olivine structure is suppressed, and the viscosity of the anode slurry is appropriate, so the coating performance is excellent.

[0125] The above-mentioned dispersant may be included in an amount of 0.1 to 3 wt% based on the total weight of the anode active material layer, specifically in the ranges of 0.1 to 1.5 wt%, 0.15 to 1 wt%, 0.2 to 0.8 wt%, and 0.3 to 0.6 wt%. By controlling the content of the dispersant to the above range, particle aggregation of the anode active material due to a low amount of dispersant can be prevented, and the problem of reduced content of the anode active material that can be introduced due to an excessive amount of dispersant can be prevented.

[0126] The thickness of the positive active material layer may be 100 μm or more and 170 μm or less, and more specifically, may be in the range of 105 μm to 165 μm; 110 μm to 160 μm; 115 μm to 160 μm; and 115 μm to 155 μm. Here, the thickness of the positive active material layer is the thickness of the positive active material layer excluding the positive current collector in the positive electrode. The thickness of the positive active material layer is the thickness based on the positive active material layer disposed on one side of the current collector in the positive electrode. If the positive electrode is a double-sided positive electrode with a structure in which positive active material layers are disposed on both sides of the current collector, the thickness of the positive active material layer may be 200 to 340 μm, more specifically, in the range of 215 to 325 μm; 230 to 310 μm; 235 to 300 μm; and 240 to 295 μm.

[0127] The above-mentioned positive active material layer may have a loading amount of 500 mg / 25 cm² or more. The loading amount of the above-mentioned positive active material layer may be in the range of 500~1500 mg / 25 cm²; 550~1300 mg / 25 cm²; 600~1200 mg / 25 cm²; 650~1100 mg / 25 cm²; 700~1000 mg / 25 cm²; 600~900 mg / 25 cm²; 625~850 mg / 25 cm²; or 650~800 mg / 25 cm². Here, the above-mentioned loading amount is a value based on the loading amount of the positive active material layer formed on one surface of the positive current collector. The above-mentioned loading amount may be the electrode loading amount after drying or the electrode loading amount after rolling. When the loading amount of the positive active material layer is within the above range, the lithium secondary battery can achieve high energy density and high power output, so it can be easily applied to devices requiring high power output, such as electric vehicles, as well as devices requiring high energy density, such as ESS.

[0128] The anode can be manufactured by applying an anode slurry to an anode current collector, drying, and rolling. The dried anode slurry becomes an anode active material layer. The anode slurry can be manufactured by adding the anode active material and binder described above to a solvent and mixing and stirring. Optionally, a conductive agent and / or a dispersant may be added during the manufacture of the anode slurry.

[0129] Meanwhile, anodes can also be manufactured using a dry method rather than the wet method described above. Since electrodes manufactured by the wet method contain a fluid solvent, phenomena such as thickness collapse occur after coating, which limits the improvement of the electrode slurry coating thickness. However, the dry method does not have these problems, making it much more advantageous for manufacturing high-loading anodes compared to the wet method. Anodes manufactured by the dry method generally contain a binder capable of fiberization. Since a binder capable of fiberization can improve the rolling performance of the anode compared to polyvinylidene fluoride, which is the anode binder, manufacturing the anode by the dry method is advantageous in terms of anode density compared to manufacturing it by the wet method.

[0130] In exemplary embodiments, a dry electrode can be manufactured by laminating a free-standing type electrode composite film, manufactured in a sheet form and comprising an electrode active material, a binder, a conductive material, etc., onto a current collector.

[0131] A method for manufacturing an anode according to exemplary embodiments may include: (a) a step of preparing a powdered mixture comprising an anode active material, a conductive material, and a binder; (b) a kneading step of kneading the powdered mixture to prepare a mixture mass; (c) a step of grinding the mixture mass to obtain a mixed powder for the anode; and (d) a step of calendering the mixed powder for the anode to prepare a composite film; and (e) a step of positioning the composite film on at least one surface of a current collector and laminating it to manufacture a dry anode.

[0132] The above positive current collector may be one that has high conductivity without causing chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, etc. may be used, and in the case of aluminum or stainless steel, one that has been surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the average thickness of the above current collector may be appropriately selected in the range of 3 to 500 μm, taking into consideration the conductivity and total thickness of the positive electrode being manufactured.

[0133] The cathode according to the present disclosure, by including the cathode active material described above, suppresses the formation of LiF at the cathode-electrolyte interface, thereby enabling the realization of a lithium secondary battery with excellent high-rate charge / discharge performance. Furthermore, the cathode of the present invention includes a cathode active material having an improved capacity development rate, thereby enabling the realization of a lithium secondary battery with high energy density.

[0134]

[0135] lithium secondary battery

[0136] A lithium secondary battery according to exemplary embodiments of the present invention comprises a positive electrode; a negative electrode; a separator; and an electrolyte, wherein the positive electrode comprises the positive electrode active material described above.

[0137] As the above-mentioned anode and anode active material have been explained in detail above, a redundant explanation will be omitted.

[0138] As a result of including the cathode in the lithium secondary battery according to the present disclosure comprising the cathode active material described above, the formation of LiF at the interface between the cathode and the electrolyte is suppressed. In exemplary embodiments, the cathode active material is LiF measured in ToF-SIMS analysis - The integral strength of (I LiFThe value of ) may be 3 or less, more specifically 0.1 or more, and 3 or less, more specifically 0.3 to 2.5, and more specifically 0.5 to 2.0. Accordingly, the lithium secondary battery of the present disclosure has excellent high-rate charge / discharge performance as a result of suppressing the accumulation of LiF that increases charge transfer resistance at the positive electrode-electrolyte interface.

[0139] The above cathode can be manufactured, for example, by preparing a cathode slurry comprising a cathode active material, a cathode binder, and a cathode conductive material, applying it onto a cathode current collector, and then drying and rolling.

[0140] The above-mentioned cathode active material is not particularly limited, and typically, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, and highly crystalline carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; or composites comprising a metallic compound and a carbonaceous material. In addition, examples of low-crystallinity carbon include soft carbon and hard carbon, while examples of high-crystallinity carbon include natural graphite, kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes. One of these alone or a mixture of two or more may be used, and a metallic lithium thin film may also be used as the negative electrode active material. Among these, natural graphite and artificial graphite have excellent density and conductivity, high capacity, and high energy density; therefore, when the negative electrode includes natural graphite and / or artificial graphite as the negative electrode active material, a battery with excellent output characteristics and rate characteristics can be realized.

[0141] The above-mentioned cathode conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it can be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. Specifically, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farness black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc., may be used. The above-mentioned cathode conductive material may typically be included in an amount of 1 to 30 weight%, specifically 0.1 to 10 weight%, and more specifically 0.5 to 5 weight% based on the total weight of the cathode active material layer.

[0142] The above-mentioned cathode binder serves to improve adhesion between cathode active material particles and adhesion between the cathode active material and the cathode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. The above-mentioned cathode binder may be included in the cathode active material layer in an amount of 0.1 to 30 weight%, more specifically 0.1 to 10 weight%, and more specifically 0.5 to 5 weight%.

[0143] Meanwhile, the above-mentioned negative current collector is not particularly limited as long as it has high conductivity 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., and aluminum-cadmium alloy may be used.

[0144] In addition, the above-mentioned negative current collector may typically have a thickness of 3 μm to 500 μm, and, similar to the positive current collector, fine irregularities may be formed on the surface of the negative current collector to strengthen the bonding force of the negative active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0145] The above separator can be any porous substrate commonly used as a separator in lithium secondary batteries, and for example, a polyolefin-based porous membrane or nonwoven fabric may be used, but is not particularly limited thereto. In particular, it is desirable that it has low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity.

[0146] Examples of the above-mentioned polyolefin-based porous membranes include membranes formed from polyolefin-based polymers such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polybutylene, and polypentene, either individually or as a mixture thereof.

[0147] In addition to polyolefin-based nonwoven fabrics, the above nonwoven fabric may be formed from polymers such as polyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, and polyethylenenaphthalene, either individually or in a mixture thereof. The structure of the nonwoven fabric may be a spunbond nonwoven fabric or a melt-blown nonwoven fabric composed of long fibers.

[0148] The thickness of the porous substrate is not particularly limited, but may be 5 to 50 μm, and the pore size and porosity present in the porous substrate are also not particularly limited, but may be 0.01 to 50 μm and 10 to 95%, respectively.

[0149] Meanwhile, to improve the mechanical strength of the separator composed of the above porous substrate and to suppress short circuits between the anode and the cathode, a porous coating layer comprising inorganic particles and a binder polymer may be further included on at least one surface of the above porous substrate.

[0150] Meanwhile, in the above lithium secondary battery, the electrolyte may include an organic solvent and a lithium salt commonly used in electrolytes, and is not particularly limited.

[0151] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene and fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC) may be used.

[0152] Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.

[0153] The above lithium salt can be used without special limitations as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. It is preferable that the lithium salt be included in the electrolyte at a concentration of approximately 0.6 mol% to 2 mol%.

[0154] In addition to the above electrolyte components, the above electrolyte may further include one or more additives, such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery. In this case, the above additives may be included in an amount of 0.1 to 5 weight% based on the total weight of the electrolyte.

[0155] The lithium secondary battery of the present invention can be manufactured by forming an electrode assembly by placing a separator between a positive electrode and a negative electrode, placing the electrode assembly into a cylindrical battery case, a prismatic battery case, or a pouch-type battery case, and then injecting an electrolyte. Alternatively, the electrode assembly may be manufactured by stacking the electrode assemblies, impregnating them with an electrolyte, placing the resulting product into a battery case, and sealing it.

[0156] Unlike the lithium secondary battery described above, the lithium secondary battery according to another embodiment of the present invention may be an all-solid-state battery.

[0157] The above battery case may be adopted from those commonly used in the field, and there are no restrictions on the external shape according to the application of the battery; for example, it may be a cylindrical shape using a can, a prismatic shape, a pouch shape, or a coin shape.

[0158] Since the lithium secondary battery according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it is useful in fields such as portable devices like mobile phones, laptop computers, and digital cameras, energy storage systems (ESS), and electric vehicles such as hybrid electric vehicles (HEV).

[0159]

[0160] The lithium secondary battery according to the exemplary embodiments of the present invention enables the realization of high energy density while having excellent rapid charging performance and resistance characteristics.

[0161]

[0162] Method for manufacturing positive electrode active material

[0163] FIG. 1 is a flowchart for explaining a method for manufacturing a positive electrode active material according to exemplary embodiments of the present invention.

[0164] Referring to FIG. 1, a method for manufacturing a positive electrode active material according to exemplary embodiments of the present invention may include a mixing step (P10), a drying step (P20), and a heat treatment step (P30). The method for manufacturing a positive electrode active material of the present invention is intended to provide a lithium transition metal oxide having an olivine-type crystal structure and containing manganese.

[0165] The above mixing step (P10) may include the process of mixing a lithium transition metal oxide having an olivine-type crystal structure into a dispersion solution containing a metalloid source. The lithium transition metal oxide having an olivine-type crystal structure may include manganese, and specifically, at least a portion of the transition metal may be substituted with manganese. In exemplary embodiments, the lithium transition metal oxide may have a molar ratio of manganese to iron in the range of 8:2 to 2:8, more specifically 75:25 to 25:75, and even more specifically 7:3 to 3:7.

[0166] In exemplary embodiments, the lithium transition metal oxide may be a compound represented by the following chemical formula 4.

[0167] [Chemical Formula 4]

[0168] Li 1+a Mn 1-b-c Fe b M 2 c PO4

[0169] In the above chemical formula 4,

[0170] M 2 is one or more of Ti, V, Zr, Sr, Sb, Co, Ni, Mg, Na, and Nb, and

[0171] a, b, and c are -0.5≤a≤0.5, 0.05≤b≤0.8, and 0≤c≤0.2.

[0172] The metalloid source is a material for providing the metalloid element constituting the metalloid compound described above. The metalloid source is not particularly limited as long as it can provide silicon (Si) and / or boron (B). As a non-limiting example, the metalloid source may be one or more mixtures selected from the group consisting of tetraethyl orthosilicate [Si(OC2H5)4], lithium metaborate (LiBO2), boron oxide (B2O3), and trimethylsiloxyboron ([B(OSiCH3)3]).

[0173] In the above mixing step (P10), the lithium transition metal oxide introduced into the dispersion solution may have a carbon coating layer. It should be noted that in the present disclosure, the lithium transition metal oxide introduced into the mixing step (P10) has a carbon coating layer on its surface. When the lithium transition metal oxide having a carbon coating layer is introduced into the dispersion solution and mixed, and the mixed solution is dried and then heat-treated, a positive electrode active material in which a metalloid compound is introduced can be obtained while the carbon coating layer is already firmly covering the surface of the lithium transition metal oxide. That is, the positive electrode active material manufactured according to the present disclosure may have a structure of a core-carbon coating layer-metalloid coating layer. Furthermore, in the positive electrode active material manufactured according to the present disclosure, there is no gap for a metalloid compound to intervene between the lithium transition metal oxide of the core and the carbon coating layer, or even if a metalloid compound exists between the lithium transition metal oxide of the core and the carbon coating layer, the amount is extremely small. Since most metalloid compounds are distributed on the surface of the positive electrode active material, the conductive network of the carbon coating layer can be maintained continuously without being interrupted by the metalloid compounds, so the electronic conductivity can be maintained at a high level.

[0174] Unlike the manufacturing method of the present invention, if a carbon source is mixed with a lithium transition metal oxide that does not have a carbon coating layer in the mixing step (P10), or if a carbon source for forming a carbon coating layer is introduced and heat treated only in the heat treatment step (P30) described later, then in the heat treatment step (P30), the carbon component of the carbon source and the metalloid component of the metalloid source chemically react in the heat treatment step (P30), thereby producing a positive electrode active material having a structure in which a metalloid compound is composited in the carbon coating layer, or a positive electrode active material having a metalloid compound randomly distributed within the carbon coating layer. This results in a structure different from the positive electrode active material manufactured according to the embodiments of the present invention. Compared to the positive electrode active material manufactured according to the present disclosure, the positive electrode active material manufactured as described above has limited conductivity of the carbon coating layer and increased resistance at the interface between the positive electrode and the electrolyte, resulting in a small charge / discharge capacity and inferior rate capability.

[0175] In order to manufacture a positive electrode active material with excellent capacity and high-rate charge / discharge performance as described above, it is preferable that the lithium transition metal oxide introduced into the dispersion solution has a carbon coating layer.

[0176] The carbon coating layer may be disposed on at least a portion of the lithium transition metal oxide surface. That is, the carbon coating layer may be disposed on a portion of the lithium transition metal oxide surface, or may be disposed over most or the entire lithium transition metal oxide surface.

[0177] The thickness of the carbon coating layer may be in the range of 0.1 nm to 5 µm, 0.5 nm to 5 µm, 1 nm to 5 µm, 1 nm to 1 µm, 1 nm to 500 nm, 1 nm to 200 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 20 nm. As the carbon coating layer has a thickness within the above range, the electronic conductivity of the positive active material may be further improved and the internal resistance may be further reduced.

[0178] In the above mixing step (P10), the concentration of the metalloid source in the dispersion solution may be in the range of 0.01~0.9 wt%, 0.02~0.7 wt%, 0.02~0.5 wt%, 0.03~0.45 wt%, 0.05~0.4 wt%, 0.06~0.4 wt%, 0.07~0.35 wt%, 0.075~0.3 wt%, and 0.8~0.2 wt%. When the concentration of the metalloid source is within the above range, the effect of improving high-rate charge / discharge performance by the metalloid compound can be optimized, and it is desirable in terms of resistance characteristics.

[0179] In the above mixing step (P10), the weight ratio of the metalloid source and the lithium transition metal oxide having an olivine-type crystal structure is 1:10 to 1:1000. Preferably, it is in the range of 1:15 to 1:750, and more preferably 1:30 to 1:500. If the weight of the metalloid source is excessively small compared to the weight of the lithium transition metal oxide, it is undesirable in terms of output characteristics and rate characteristics, and if the weight of the metalloid source is excessively large compared to the weight of the lithium transition metal oxide, the thickness of the metalloid coating layer becomes thicker than necessary, which may increase resistance and is therefore undesirable.

[0180] The solvent of the dispersion solution is not particularly limited as long as it is capable of dispersing the metalloid source and the lithium transition metal oxide. Non-limiting examples of solvents included in the dispersion solution include ethanol, acetone, n-propanol, isopropanol, methylpyrrolidone (NMP; N-Methyl-2-pyrrolidinone), etc.

[0181] The mixing method in the above mixing step (P10) is not particularly limited. In some embodiments, the mixing step (P20) may include the process of preparing a pre-dispersed solution by dispersing the metalloid source in an organic solvent, adding a lithium transition metal oxide to the prepared pre-dispersed solution, and stirring. In other embodiments, the mixing step (P20) may include the process of adding the metalloid source and the lithium transition metal oxide to an organic solvent at once and stirring.

[0182] The stirring time in the above mixing step is not particularly limited as long as the metalloid source can be sufficiently mixed between the lithium transition metal oxides. As a non-limiting example, the stirring time may be in the range of 0.5 to 12 hours, 0.5 to 10 hours, 0.5 to 5 hours, 1 to 10 hours, or 1 to 5 hours.

[0183] In the above mixing step (P10), the temperature may be in the range of 5 to 80°C, 5 to 75°C, 10 to 70°C, or 15 to 70°C. However, it is not limited thereto.

[0184] The drying step (P20) may be a step of drying the mixture. By removing the solvent through drying the mixture in the drying step (P20), a lithium transition metal oxide coated with a metalloid source can be obtained. In some embodiments, the drying step (P20) may include a process of washing and drying the lithium transition metal oxide from the mixed solution obtained in the mixing step (P20).

[0185] The drying step (P20) is not particularly limited as long as it is a method capable of removing the solvent. The drying temperature may be a temperature range exceeding the vaporization point of the solvent. In some embodiments, the drying temperature may be in the range of 60 to 120°C, 70 to 110°C, or 80 to 100°C, but is not limited thereto.

[0186] The heat treatment step (P30) above may be a process of reacting the lithium transition metal oxide coated with the metalloid source obtained in the drying step (P20) at a high temperature. Through the heat treatment step, the metalloid source may react with the lithium transition metal oxide to produce a metalloid compound and a Li-MO complex compound.

[0187] In an exemplary embodiment, a carbon source for forming a carbon coating layer is not introduced in the heat treatment step (P30). Accordingly, the metalloid compound and the Li-MO composite compound are not composited into the carbon coating layer, and most of the metalloid compound and the Li-MO composite compound can be disposed on the surface of the cathode active material. Since the metalloid compound and the Li-MO composite compound have been described in detail above, a redundant description will be omitted.

[0188] In the above heat treatment step (P30), the heat treatment temperature may be in the range of 400 to 700°C, preferably 450 to 650°C, and more preferably 500 to 600°C. When heat treatment is performed in the above temperature range, the effect of improving the high-rate charge / discharge characteristics of the positive active material is excellent.

[0189] In the above heat treatment step (P30), the heat treatment time may be in the range of 1 to 10 hours, preferably 2 to 8 hours, and more preferably 4 to 6 hours. When heat treatment is performed for a time within the above range, the effect of improving the high-rate charge / discharge characteristics of the positive electrode active material is excellent.

[0190] The above heat treatment step (P30) can be performed under an inert gas atmosphere, such as argon gas. When the heat treatment step is performed under an inert gas atmosphere, a pure metalloid coating layer can be formed while preserving the original crystal structure and oxidation state of the lithium transition metal oxide. Furthermore, since heat treatment under an inert gas does not cause abrupt chemical changes, the metalloid compound can spread evenly on the surface of the lithium transition metal oxide particles of the core, thereby further enhancing the effect of improving the output performance of the lithium transition metal oxide containing manganese. The above inert gas is not particularly limited as long as it has no chemical reactivity or very little reactivity, and specifically, examples include argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon (Xe), and nitrogen (N2) gases.

[0191] The positive electrode active material prepared according to exemplary embodiments of the present invention may be the positive electrode active material described above. For example, the positive electrode active material prepared according to exemplary embodiments of the present invention may comprise a core comprising lithium transition metal oxide particles having an olivine-type crystal structure; a carbon coating layer disposed on at least a portion of the surface of the core; and a metalloid coating layer disposed on at least a portion of the surface of the carbon coating layer, wherein the lithium transition metal oxide comprises manganese, and the metalloid coating layer may comprise a metalloid compound having one or two metalloid elements selected from the group consisting of silicon (Si) and boron (B); and a Li-MO composite compound (wherein M is the metalloid element).

[0192] As the structure and characteristics of the positive electrode active material of the present invention have been explained in detail above, further detailed explanation will be omitted.

[0193] The present invention will be explained in more detail below through examples. However, the following examples are intended to illustrate the present invention and do not limit the scope of the present invention.

[0194]

[0195] Example 1

[0196] 900 ml of an ethanol solution in which tetraethyl orthosilicate [Si(OC2H5)4] was dissolved at a concentration of 0.1 wt% as a metalloid source was prepared. LiMn with a carbon coating layer disposed on its surface 0.6 Fe 0.4 300g of PO4 was added to the above ethanol solution. Subsequently, a mixed solution was prepared by stirring at a rotational speed of 400 rpm in a temperature environment of 70°C. The above mixed solution was dried in a vacuum oven at a temperature of 80°C for 1 hour. Subsequently, a positive electrode active material was prepared by heat treatment at a temperature of 600°C for 5 hours in an argon gas atmosphere.

[0197]

[0198] Examples 2 to 6

[0199] Each of the positive electrode active materials of Examples 2 to 6 was prepared in the same manner as Example 1, except that the concentration of the metalloid source, the heat treatment temperature, and the heat treatment time in the above ethanol solution were changed as shown in Table 1 below.

[0200] Concentration (wt%) Heat Treatment Temperature (°C) Heat Treatment Time (hour) Example 1 0.16005 Example 2 0.16001 Example 3 0.15501 Example 4 0.16007.5 Example 5 0.56005 Example 6 16005

[0201]

[0202] Example 7

[0203] 900 ml of an ethanol solution in which lithium metaborate (LiBO2) was dissolved at a concentration of 0.1 wt% as a metalloid source was prepared. LiMn with a carbon coating layer disposed on its surface 0.6 Fe 0.4300g of PO4 was added to the above ethanol solution. Subsequently, a mixed solution was prepared by stirring at a rotational speed of 400 rpm in a temperature environment of 70°C. The above mixed solution was dried in a vacuum oven at a temperature of 80°C for 1 hour. Subsequently, a positive electrode active material was prepared by heat treatment at a temperature of 600°C for 5 hours in an argon gas atmosphere.

[0204]

[0205] Comparative Example 1

[0206] 900 ml of an ethanol solution was prepared in which tetraethyl orthosilicate [Si(OC2H5)4] and ethyl cellulose as a carbon precursor were dissolved at a concentration of 0.1 wt% each. Carbon-uncoated LiMn 0.6 Fe 0.4 300g of PO4 was added to the above ethanol solution. Subsequently, a positive electrode active material was prepared in the same manner as in Example 1.

[0207]

[0208] Comparative Example 2

[0209] 900 ml of ethanol solution was prepared in which tetraethyl orthosilicate [Si(OC2H5)4] and polyvinylpyrrolidone as a carbon precursor were dissolved at a concentration of 0.1 wt% each. Carbon-uncoated LiMn 0.6 Fe 0.4 300g of PO4 was added to the above ethanol solution. Subsequently, a positive electrode active material was prepared in the same manner as in Example 1.

[0210]

[0211] Comparative Example 3

[0212] LiMn with a carbon coating layer disposed on the surface used in Example 1 above 0.6 Fe 0.4 PO4 was prepared as the positive active material.

[0213]

[0214] Experimental Example 1: Surface Analysis of Anode Active Material

[0215] For each cathode active material of Example 1 and Comparative Example 3, the types and amounts of elements or molecules constituting the surface of the cathode active material were analyzed using Secondary Ion Mass Spectrometry (SIMS) (ToF-SIMS).

[0216] The results are shown in Figures 2 to 6.

[0217] Figure 2 shows Si by ToF-SIMS - This is the depth profile, and Fig. 3 shows SiO2 by ToF-SIMS. - Figure 4 is a depth profile of the fragments detected during ToF-SIMS analysis of the positive electrode active material of Example 1, Figure 5 is a depth profile of the fragments detected during ToF-SIMS analysis of the positive electrode active material of Comparative Example 3, and Figure 6 is a bar graph showing the integral intensity of each fragment measured during ToF-SIMS analysis.

[0218] Referring to FIGS. 2 and 3, the positive active material according to Example 1 is Si - and SiO2 - It can be seen that the intensity has increased significantly compared to the positive electrode active material of Comparative Example 3. Therefore, it can be confirmed that a metalloid compound exists on the surface of the positive electrode active material according to the embodiment of the present invention.

[0219] Referring to FIGS. 4 and 5, unlike the cathode active material of Comparative Example 3, the cathode active material of Example 1 shows Li2SiO2 as the sputtering time increases. - It can be observed that the intensity tends to increase and then maintain the increased value. Also, referring to Fig. 6, the Li2SIO measured in the ToF-SIMS analysis - The integral strength of (I Li2SiOIn terms of the value of ), the cathode active material according to Example 1 has a much larger value than the cathode active material according to Comparative Example 3. As described above, the cathode active material according to the present invention is expected to have improved electrochemical performance while enhancing lithium ion mobility by having an abundance of Li-MO composite compounds on its surface.

[0220]

[0221] A positive electrode was prepared using each positive electrode active material of Example 1 and Comparative Example 3, and a coin-type battery cell with lithium as the counter electrode was prepared.

[0222] To manufacture the above anode, an anode slurry was first prepared by mixing and stirring an anode active material, conductive carbon, and polyvinylidene fluoride (PVDF) in an N-methyl-2-pyrrolidone (NMP) solvent at a weight ratio of 95:2:3. The anode was manufactured by coating the prepared anode slurry onto aluminum foil, drying, and rolling. The manufactured anode had a volume of 575 mg / 25 cm 2 It had a loading amount.

[0223] As an electrolyte to be injected into the above coin-type battery cell, an electrolyte was used in which 0.3 wt% of vinylene carbonate (VC) and 0.5 wt% of fluoroethylene carbonate (FEC) were added to an organic solvent mixed in a volume ratio of 5:3:2 of ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC), and LiPF6 was dissolved at a concentration of 1.2 M.

[0224] The above coin-type battery cell was left at room temperature to allow the electrolyte to sufficiently impregnate the positive electrode and the lithium counter electrode, and then charged to SOC 60% with a constant current of 0.33C. Afterwards, the battery was left at room temperature for 12 hours to age the battery cell.

[0225] Subsequently, the battery cell was disassembled, and a sample was taken from the cathode. The types and amounts of elements and molecules constituting the surface of the cathode active material were analyzed using Secondary Ion Mass Spectrometry (SIMS) (ToF-SIMS). Then, LiF in the cathode active material - A 3D mapping image showing the distribution of is shown in Fig. 7. In addition, F measured in the ToF-SIMS analysis - A graph showing the integral strength values ​​of the species is shown in Fig. 8.

[0226] Referring to FIG. 7, in the cathode active material of Example 1, LiF - The signal is LiF in the cathode active material of Comparative Example 3. - It can be confirmed that it is much smaller than the signal. Referring to Fig. 8, in the cathode active material of Example 1, LiF - The detected amount of LiF in the cathode active material of Comparative Example 3 is - It can be confirmed that it decreased by 74.54% compared to the detected amount of LiF - F outside - The species also showed a significant decrease in the cathode active material of Example 1 compared to the cathode active material of Comparative Example 3, and in particular MnF3 - and FeF3 - It can be confirmed that it was hardly detected in the positive active material of Example 1.

[0227] As described above, it can be confirmed that the cathode active material of the present invention suppresses the generation of LiF during the operation of the battery. Therefore, the cathode and lithium secondary battery of the present disclosure are expected to have improved high-rate charge / discharge performance, capacity characteristics, and cycle characteristics.

[0228]

[0229] Experimental Example 2: Impedance Measurement

[0230] A positive electrode was prepared using each positive electrode active material of Example 1 and Comparative Example 3, and a coin-type battery cell with lithium as the counter electrode was prepared. With the coin-type battery cell fully charged to 4.4V, the voltage was fixed and the impedance was measured while varying the frequency from 1MHz to 0.01Hz with an amplitude of 10mV. The results are shown as the Nyquist plot in Fig. 9.

[0231] In the Nyquist plot of Fig. 9, the radius of the semicircle is the charge transfer resistance (R ct It can be interpreted as follows. It can be confirmed that the charge transfer resistance of Example 1 is smaller than the charge transfer resistance of Comparative Example 3. Therefore, compared to the cathode active material of Comparative Example 3, the cathode active material of Example 1 is expected to improve the charge and discharge speed of the battery by increasing the speed of electron and lithium ion movement. As described above, the cathode active material according to the embodiment of the present invention is expected to increase charge output and improve high-rate charge / discharge performance by having a small charge transfer resistance.

[0232]

[0233] Experimental Example 3: Evaluation of Rate Competence Characteristics

[0234] A positive electrode was prepared using each of the positive electrode active materials of Examples 1 to 7 and Comparative Examples 1 to 3, and a coin-type battery cell with lithium as the counter electrode was prepared. For each coin-type battery cell, a charge-discharge test was conducted at a temperature of 25°C under the following conditions. During the charge-discharge test, the CC current was set to 1C. The 1C charge capacity and 1C discharge capacity were measured during the charge-discharge test.

[0235] Charging: CC / CV, 4.2V, 0.05C cut-off

[0236] Discharge: CC, 2.5V cut-off

[0237] Then, the CC current was set to 2C, and the 2C charging capacity and 2C discharging capacity were measured in the same way as above, and the results are shown in Table 2.

[0238] In addition, the percentage of the 2C discharge capacity relative to the 1C discharge capacity was calculated as a rate characteristic, and the results are shown in Table 2.

[0239] Rate Characteristic (%) = (2C Discharge Capacity / 1C Discharge Capacity) × 100

[0240] 1C Charge Capacity (mAh / g) 1C Discharge Capacity (mAh / g) 2C Charge Capacity (mAh / g) 2C Discharge Capacity (mAh / g) Rate Characteristic (%) Example 1 114.36 114.77 106.5 2100.6788 Example 2 113.94 113.89 102.189 5.6484 Example 3 99.94 99.87 85.367 8.6179 Example 4 98.19 98.57 89.15 82.984 Example 5 115.54 111.37 98.68 92.0482 Example 6 109.19 109.24 97.56 90.9583 Example 7 100.42 100.21 91.17 84.0284 Comparative Example 197.4697.5485.6479.5682 Comparative Example 2105.02104.8695.0188.985 Comparative Example 3112.23112.1484.7476.4568

[0241] Referring to Table 2, the positive active materials of Examples 1 to 7 have larger 2C charge capacity and 2C discharge capacity and excellent rate characteristics compared to the positive active material of Comparative Example 3.

[0242] The positive electrode active material according to Comparative Example 1 was found to have smaller 1C charge capacity, 1C discharge capacity, 2C charge capacity, and 2C discharge capacity, and inferior rate characteristics compared to the positive electrode active material of Example 1. This is analyzed to be because the carbon component of ethyl cellulose and the silicon component of the metalloid source chemically reacted together during the heat treatment step, resulting in the production of a positive electrode active material with a structure different from that of the positive electrode active materials according to the examples.

[0243] The positive electrode active material according to Comparative Example 2 also showed smaller 1C charge capacity, 1C discharge capacity, 2C charge capacity, and 2C discharge capacity, and inferior rate characteristics compared to the positive electrode active material of Example 1. This is analyzed to be because the carbon component of polyvinylpyrrolidone and the silicon component of the metalloid source chemically reacted together during the heat treatment step, resulting in the production of a positive electrode active material with a structure different from that of the positive electrode active materials according to the examples.

[0244] From these results, it is considered desirable to introduce a metalloid oxide into a lithium transition metal oxide that already has a carbon coating layer when manufacturing the cathode active material.

[0245] Meanwhile, referring to Examples 1 to 6, it was found that the concentration of the metalloid source in the ethanol solution, the heat treatment temperature, and the heat treatment time affect the characteristics of the cathode active material. Therefore, in the present invention, the effects of the present invention can be maximized by optimizing the concentration of the metalloid source in the ethanol solution, the heat treatment temperature, and the heat treatment time.

[0246]

[0247] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

Claims

1. A core comprising lithium transition metal oxide particles having an olivine-type crystal structure; A carbon coating layer disposed on at least a portion of the core surface; and It includes a metalloid coating layer disposed on at least a portion of the surface of the carbon coating layer, and The above lithium transition metal oxide contains manganese, and The metalloid coating layer comprises: a metalloid compound having one or two metalloid elements selected from the group consisting of silicon (Si) and boron (B); and a Li-MO complex compound (wherein M is the metalloid element). Positive active material.

2. In Paragraph 1, The above Li-MO composite compound is an anode active material that is also present at the interface between the carbon coating layer and the metalloid coating layer.

3. In Paragraph 1, When analyzing the depth profile by ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry), the intensity of the Li-MO composite compound increases in the sputtering time range of Os to 100 s, and I, which is the average intensity of the Li-MO composite compound in the sputtering time range of 200 s to 800 s, is 200~800 I, which is the average intensity of the Li-MO composite compound in the sputtering time range of 0s to 100s. 0~100 Maintained higher, Positive active material.

4. In Paragraph 1, The above metalloid compound comprises a compound represented by any one of the following chemical formulas 1 to 3, and is an anode active material: [Chemical Formula 1] Not. P In the above chemical formula 1, 0≤p≤2. [Chemical Formula 2] B q O r In the above chemical formula 2, 0≤q≤3 and 0≤r≤3. [Chemical Formula 3] Above B q O r ·SiO P In chemical formula 3, 0≤p≤2, 0≤q≤3, and 0≤r≤3.

5. In Paragraph 1, The above lithium transition metal oxide is a positive electrode active material comprising a compound represented by the following chemical formula 4. [Chemical Formula 4] Li 1+a Mn 1-b-c Fe b M 2 c PO4 In the above chemical formula 4, M 2 is one or more of Ti, V, Zr, Sr, Sb, Co, Ni, Mg, Na, and Nb, and a, b, and c are -0.5≤a≤0.5, 0.05≤b≤0.8, and 0≤c≤0.

2.

6. In Paragraph 1, The above-mentioned cathode active material is SiO2 measured in ToF-SIMS analysis. - The integral strength of (I SiO2 Li2SiO for ) - The integral strength of (I Li2SiO The ratio value of ) (I Li2SiO / I SiO2 ) being 1.0 or higher, Positive active material.

7. In Paragraph 1, The above-mentioned cathode active material is Li2SiO2 measured in ToF-SIMS analysis. - The integral strength of (I Li2SiO The value of ) is in the range of 0.1 to 1.0, Positive active material.

8. In Paragraph 4, The metalloid compound is one selected from the compounds represented by Chemical Formula 2 and Chemical Formula 3, and In the above Li-MO complex compound, M is boron, Positive active material.

9. A positive electrode comprising a positive electrode active material according to paragraph 1.

10. A lithium secondary battery comprising a positive electrode including a positive electrode active material according to claim 1; a negative electrode; an electrolyte; and a separator.

11. A mixing step of mixing a lithium transition metal oxide having an olivine-type crystal structure into a dispersion solution containing a metalloid source; A drying step for drying the above mixture; and Includes a heat treatment step, A method for manufacturing a positive electrode active material, characterized in that the above lithium transition metal oxide has a carbon coating layer.

12. In Paragraph 11, A method for manufacturing an anode active material, wherein the carbon coating layer is disposed on at least a portion of the surface of the lithium transition metal oxide.

13. In Paragraph 11, A method for manufacturing an anode active material, wherein the metalloid source is one or more mixtures selected from the group consisting of tetraethyl orthosilicate [Si(OC2H5)4], lithium metaborate (LiBO2), boron oxide (B2O3), and trimethylsiloxyboron ([B(OSiCH3)3]).

14. In Paragraph 11, A method for manufacturing an anode active material, wherein, in the above mixing step, the concentration of the metalloid source in the dispersion solution is in the range of 0.01 to 0.9 weight%.

15. In Paragraph 11, A method for manufacturing a positive electrode active material, wherein in the above mixing step, the weight ratio of the metalloid source to the lithium transition metal oxide having an olivine-type crystal structure is 1:10 to 1:1000.

16. In Paragraph 11, A method for manufacturing an anode active material, wherein the above heat treatment step is performed under an inert atmosphere.

17. In Paragraph 11, A method for manufacturing an anode active material, wherein, in the above heat treatment step, the heat treatment temperature is in the range of 400 to 700℃.

18. In Paragraph 11, A method for manufacturing an anode active material, wherein the heat treatment time in the above heat treatment step is in the range of 1 to 10 hours.

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