Cathode active material for lithium secondary battery and method for manufacturing same

Abstract

Disclosed is a method for manufacturing a lithium manganese iron phosphate (LMFP) cathode active material for a lithium secondary battery. The cathode active material according to the present invention comprises LMFP represented by LiMnaFebPO4 (a + b = 1, a > 0, b > 0), and satisfies relational expression 1. [Relational expression 1] Norm.I (101) ≥ 64.6 In relational expression 1, Norm.I (101) is defined as [intensity of (101) plane peak / intensity of (311) plane peak] × 100, and the intensity of (311) plane peak is the intensity of the strongest peak of the LMFP measured by X-ray diffraction analyzer.

Description

Cathode active material for lithium secondary batteries and method for manufacturing the same

[0001] The present invention relates to a lithium manganese iron phosphate (LMFP) positive electrode active material for a lithium secondary battery and a method for manufacturing the same.

[0002] Lithium iron phosphate (LFP) cathode active material is an olivine-based structure composed of octahedral sites of FeO6 and tetrahedral sites of PO4, and is a material in which lithium ions are deinserted and inserted through a one-dimensional pathway.

[0003] LFP cathode active materials consist of Li, Fe, and P, and offer a cost advantage due to the lower cost of metal minerals compared to NCA or NCM materials that primarily use Ni and Co.

[0004] In addition, LFP cathode active material has the advantage of excellent thermal stability because its structure is stable due to strong PO bonds, preventing oxygen dissociation at high temperatures during charging.

[0005] In addition, LFP cathode active materials have excellent lifespan characteristics, and there is a history of many electric vehicles being produced in China using them.

[0006] However, LFP cathode active materials have the disadvantage of low energy density.

[0007] To address these drawbacks, research is currently underway on lithium manganese iron phosphate (LMFP) cathode active materials in which manganese (Mn) is substituted for the iron (Fe) sites of LFP cathode active materials.

[0008] Because LMFP cathode active material is rich in manganese compared to LFP cathode active material, it has the advantage of increasing energy density by about 15% as the operating voltage increases.

[0009] However, LMFP cathode active materials have the disadvantage of lower lithium ion diffusion rate and electrical conductivity compared to LFP cathode active materials, so they are being studied from various perspectives by controlling various factors that can affect electrochemical performance.

[0010] The objective of the present invention is to provide a positive electrode active material with excellent initial discharge capacity and a method for manufacturing the same by increasing the intensity of the (101) plane peak, which indicates the degree of crystallographic filling of Li ions.

[0011] In addition, the objective of the present invention is to provide a positive electrode active material with improved ion conductivity by increasing the Li-O bond distance and a method for manufacturing the same.

[0012] In addition, the objective of the present invention is to provide a positive electrode active material and a method for manufacturing the same, which can improve the low electrical conductivity of an LMFP by uniformly coating carbon on the surface of the LMFP.

[0013] In addition, the objective of the present invention is to provide a lithium secondary battery using the above-mentioned positive electrode active material.

[0014] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0015] The positive active material according to the present invention is LiMn a Fe b It is characterized by including an LMFP represented by PO4(a + b = 1, a > 0, b > 0) and satisfying the following relationship 1.

[0016] [Relationship 1]

[0017] Norm.I (101) ≥ 64.6

[0018] In the above equation 1, Norm.I (101) is [(101) plane peak intensity / (311) plane peak intensity] × 100, and the (311) plane peak intensity is the intensity of the strongest peak of the LMFP measured by an X-ray diffraction analyzer.

[0019] The above positive active material may further satisfy the following relationship 2.

[0020] [Relationship 2]

[0021] (Li-O1*Li-O2*Li-O3) ≥ 9.95

[0022] For lithium in the lattice structure of the LMFP measured by an X-ray diffraction analyzer in the above equation 2, when the bond distances (Å) with oxygen of different axial directions are denoted as Li-O1, Li-O2, and Li-O3, (Li-O1*Li-O2*Li-O3) means the product of Li-O1, Li-O2, and Li-O3.

[0023] At this time, the above Li-O1 may be 2.193 to 2.2 Å, the above Li-O2 may be 2.099 to 2.2 Å, and the above Li-O3 may be 2.158 to 2.2 Å.

[0024] For a total of 100 mol%, it may further include 0.5 to 1.5 mol% of a dopant.

[0025] The above dopant may include one or more of Al, Zr, Nb, Mo, W, Ti, Ce, Mg, B, Y, P, V, and Sr.

[0026] The above LMFP surface may further include a carbon layer coated thereon.

[0027] At this time, the carbon content of the carbon layer may be 1 to 3 weight percent with respect to 100 weight percent of the total.

[0028] The average crystal size of the above positive active material may be 70 to 110 nm.

[0029] A lithium secondary battery according to the present invention is characterized by comprising: a positive electrode including the aforementioned positive electrode active material; a negative electrode; and an electrolyte.

[0030] A method for manufacturing a positive electrode active material according to the present invention comprises: (a) a step of preparing and grinding an LMFP precursor; (b) a step of spray-drying the slurry obtained by grinding; and (c) a step of calcining the powder obtained by spray-drying to manufacture a positive electrode active material; wherein the LMFP is LiMn a Fe b It is represented as PO4(a + b = 1, a > 0, b > 0) and is characterized by satisfying the following relationship 1.

[0031] [Relationship 1]

[0032] Norm.I (101) ≥ 64.6

[0033] In the above equation 1, Norm.I (101) is [(101) plane peak intensity / (311) plane peak intensity] × 100, and the (311) plane peak intensity is the intensity of the strongest peak of the LMFP measured by an X-ray diffraction analyzer.

[0034] The above method for manufacturing the positive electrode active material may further satisfy the following relationship 2.

[0035] [Relationship 2]

[0036] (Li-O1*Li-O2*Li-O3) ≥ 9.95

[0037] For lithium in the lattice structure of the LMFP measured by an X-ray diffraction analyzer in the above equation 2, when the bond distances (Å) with oxygen of different axial directions are denoted as Li-O1, Li-O2, and Li-O3, (Li-O1*Li-O2*Li-O3) means the product of Li-O1, Li-O2, and Li-O3.

[0038] In step (a) above, grinding can be performed at a rotational speed of 3000 to 3500 rpm / min using beads with a size of 0.3 to 0.5 mm.

[0039] In step (b) above, the average particle size (D50) of the slurry obtained by grinding may be 100 to 240 nm.

[0040] The step of (a) preparing and grinding the LMFP precursor above can be performed by mixing and milling the lithium precursor, phosphorus precursor, iron precursor, and manganese precursor for 2 to 5 hours.

[0041] In step (a) above, 10% by weight or less of a carbon precursor may be further mixed with the LMFP precursor with respect to 100% by weight of the total.

[0042] In step (a) above, the carbon precursor may include one or more of glucose, sucrose, fructose, lactose, maltose, graphite, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, a material having a crystal structure including graphene, and a material having a crystal structure including graphite.

[0043] In step (a) above, 0.5 to 1.5 mol% of dopant may be further mixed with respect to the total 100 mol%.

[0044] In step (a) above, the dopant may include one or more of Al, Zr, Nb, Mo, W, Ti, Ce, Mg, B, Y, P, V, and Sr.

[0045] In step (c) above, calcination can be performed in an inert atmosphere at 630 to 700°C.

[0046] In step (a) above, one or more dispersants selected from citric acid, fumaric acid, adipic acid, succinic acid, tartaric acid, glutaric acid, maleic acid, oxalic acid, malonic acid, and ascorbic acid may be further mixed.

[0047] A method for manufacturing a positive electrode active material according to another embodiment of the present invention comprises: (a) a step of preparing and grinding an LMFP precursor; (b) a step of spray-drying the slurry obtained by grinding; and (c) a step of calcining the powder obtained by spray-drying to manufacture a positive electrode active material; and is characterized by satisfying the following equation 1.

[0048] [Relationship 1]

[0049] Norm.I (101) ≥ 64.6

[0050] In the above equation 1, Norm.I (101) is [(101) plane peak intensity / (311) plane peak intensity] × 100, and the (311) plane peak intensity is the intensity of the strongest peak of the LMFP measured by an X-ray diffraction analyzer.

[0051] According to the present invention, the average particle size (D50) of the slurry can be lowered to increase crystallization and the average crystal size of the positive electrode active material can be lowered.

[0052] As a result, the structural characteristics and ionic conductivity can be improved by increasing the intensity of the (101) plane peak where the Li ion is located and increasing the Li-O bond distance.

[0053] In addition, the method for manufacturing the positive electrode active material of the present invention further enhances the electrochemical reaction of the lithium secondary battery and has the effect of providing an excellent initial discharge capacity.

[0054] In addition, according to the present invention, the low electrical conductivity of the LMFP is improved by a carbon layer uniformly coated on the surface of the LMFP.

[0055] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0056] Figure 1 is an LMFP lattice structure related to the bonding distance of Li-O according to the present invention.

[0057] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0058] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0059] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0060] Hereinafter, a positive electrode active material for a lithium secondary battery and a method for manufacturing the same according to some embodiments of the present invention will be described.

[0061] Research is underway on lithium manganese iron phosphate (LMFP) cathode active materials in which manganese (Mn) is substituted for the iron (Fe) in lithium iron phosphate (LFP) cathode active materials.

[0062] LMFP cathode active material has the disadvantage of lower lithium ion diffusion rate and electrical conductivity compared to LFP cathode active material.

[0063] Accordingly, LMFP cathode active materials are being studied from various perspectives by controlling various factors that can affect electrochemical performance, such as electrical conductivity.

[0064] After a long period of research, the inventors confirmed that there is a difference in the discharge capacity of a lithium secondary battery depending on the peak intensity of the (101) plane where Li ions are present in the LMFP lattice structure and the Li-O bond distance.

[0065] The exposure of the (101) plane where the Li ions are located in the LMFP had a close effect on the performance of the LMFP cathode material.

[0066] (101) The high exposure of the plane means that there are relatively many (101) planes and the relative peak intensity is high.

[0067] Having many (101) planes where Li ions exist means that there are more transfer channels for Li ions in the

[0010] direction, which facilitates the movement of Li ions and induces improved electrochemical performance.

[0068] In addition, the high peak intensity of the (101) plane indicates that the crystallization is relatively good. This means that there are relatively few defects that hinder the movement of Li ions, such as metal elements attempting to substitute for Li sites.

[0069] Accordingly, since the peak intensity of the (101) plane affects electrochemical performance, the peak intensity of the (101) plane was determined to be a significant parameter.

[0070] Since X-ray diffraction patterns vary depending on measurement conditions such as analytical equipment, sample condition, and analysis time, it is necessary to normalize peak intensities for equivalent comparison among multiple samples. Furthermore, normalized peak intensity (Norm.I (Normalized Intensity)) is useful for evaluating the relative exposure or crystallinity of specific crystal planes.

[0071] The normalization of peak intensity is calculated by dividing each peak by the intensity of the highest peak and multiplying by 100, and the normalized peak intensity of the highest peak becomes 100.

[0072] Accordingly, the inventors calculated the Norm.I of the (101) plane by measuring with an X-ray diffraction analyzer, whereby the (311) plane exhibited the strongest (highest) peak of the LMFP, and by dividing the intensity of the (101) plane peak by the intensity of the strongest peak and multiplying by 100.

[0073] [Relation 1] related to Norm.I (101) is Norm.I (101) ≥ 64.6.

[0074] As explained earlier, Norm.I (101) means [intensity of the (101) plane peak / intensity of the (311) plane peak] × 100.

[0075] The inventors confirmed that when Norm.I (101) is satisfied at 64.6 or higher, the movement of Li ions becomes smooth and crystallization is relatively well achieved, and the electrochemical performance is improved, resulting in an initial discharge capacity of 150 mAh / g or higher.

[0076] Conversely, if Norm.I (101) is less than 64.6, it means that the relative peak intensity of the (101) plane is low, so it was difficult to secure the initial discharge capacity due to the low mobility of Li ions.

[0077] Therefore, the present invention has technical significance in that it can secure an excellent initial discharge capacity of a lithium secondary battery by satisfying Norm.I (101) ≥ 64.6.

[0078] In addition to Norm.I (101), the difference in discharge capacity of a lithium secondary battery according to the Li-O bond distance was also confirmed in the present invention.

[0079] Li ions combine with oxygen within the lattice to form LiO hexahedrons. Electrochemical performance is then manifested through the movement of Li ions between oxygen atoms.

[0080] The bond distance of Li-O forms a path through which Li ions can move, and the longer this Li-O bond distance, the smoother the movement of Li ions becomes and the higher the ionic conductivity.

[0081] Generally, ions connected by strong bonds require a greater barrier energy to break the bond and move.

[0082] Therefore, weak bonds like Li-O are electrochemically advantageous for the movement of Li ions.

[0083] Based on these research results, the inventors determined that the bond distance of Li-O is related to ionic conductivity and that the bond distance of Li-O is an important performance factor that determines the electrochemical performance of LMFP.

[0084] Figure 1 is an LMFP lattice structure related to the bonding distance of Li-O according to the present invention.

[0085] As shown in Fig. 1, the central Li ion combines with three oxygen ions, O1, O2, and O3, to form a LiO hexahedron. Within the lattice, there are Li-O1, Li-O2, and Li-O3 bonds, respectively, and the Li-O bond distance varies depending on the respective axial direction.

[0086] Since each bond distance has a significant effect on ion conductivity, the inventors completed Equation 2 by multiplying all Li-O bond distances along each axial direction.

[0087] For lithium within the lattice structure of LMFP measured by an X-ray diffraction analyzer, when the bond distances (Å) with oxygen of different axial directions are denoted as Li-O1, Li-O2, and Li-O3, the product of Li-O1, Li-O2, and Li-O3 is defined as (Li-O1*Li-O2*Li-O3).

[0088] [Equation 2] related to (Li-O1*Li-O2*Li-O3) is (Li-O1*Li-O2*Li-O3) ≥ 9.95.

[0089] The inventors confirmed that when (Li-O1*Li-O2*Li-O3) satisfies 9.95 or higher, the movement of Li ions becomes smooth and the ion conductivity improves, resulting in an initial discharge capacity of 150 mAh / g or higher.

[0090] Conversely, if (Li-O1*Li-O2*Li-O3) is less than 9.95, it means that the Li-O bond distance is short, which means that there is a strong bond between the Li ion and the O ion.

[0091] Furthermore, the relatively short bond distance between Li ions and O ions means that the activation energy barrier for Li ions to break their bond with oxygen and move is high, resulting in lower mobility and ionic conductivity of Li ions.

[0092] Therefore, when [Equation 2] was less than 9.95, it was difficult to secure the initial discharge capacity.

[0093] The present invention has technical significance in that it can secure an excellent initial discharge capacity of a lithium secondary battery by satisfying (Li-O1*Li-O2*Li-O3) ≥ 9.95.

[0094] Cathode active material for lithium secondary batteries

[0095] The positive active material according to the present invention is LiMn a Fe b It is characterized by including an LMFP represented by PO4(a + b = 1, a > 0, b > 0) and satisfying the following relationship 1.

[0096] [Relationship 1]

[0097] Norm.I (101) ≥ 64.6

[0098] In the above equation 1, Norm.I (101) is [(101) plane peak intensity / (311) plane peak intensity] × 100, and the (311) plane peak intensity is the intensity of the strongest peak of the LMFP measured by an X-ray diffraction analyzer.

[0099] Preferably, Equation 1 may be 64.6 ≤ Norm.I (101) ≤ 66, and more preferably 64.6 ≤ Norm.I (101) ≤ 65.

[0100] As Norm.I (101) increases, insertion of Li ions into the (101) plane becomes easier, increasing the degree to which Li ions are well filled and improving electrochemical properties.

[0101] Norm.I (Normalized Intensity) included in Equation 1 is a value obtained by normalizing the peak intensity of the measured diffraction pattern, making it easy to compare various samples equally. In addition, Norm.I is useful for evaluating the relative exposure or crystallinity of specific crystal planes.

[0102] Specifically, in relation 1, Norm.I (101) can be measured as follows.

[0103] After measuring the diffraction pattern with the scan range (10 ~ 80˚) and scan speed (2.5˚ / min) of the X-ray diffraction analyzer (Rigaku equipment), the diffraction data of each plane was analyzed by fitting with the Psudo-Voigt function. Then, assuming the intensity value of the highest peak was 100, the peak value of plane (101) was converted to calculate Normal. I(101).

[0104] The positive active material of the present invention has strong PO bonds, providing structural stability, and exhibits electrochemical performance through the movement of Li ions between oxygen atoms.

[0105] In this regard, the positive active material of the present invention can further satisfy the following relationship 2.

[0106] [Relationship 2]

[0107] (Li-O1*Li-O2*Li-O3) ≥ 9.95

[0108] Preferably, Equation 2 may be 9.95 ≤ (Li-O1*Li-O2*Li-O3) ≤ 10, and more preferably 9.95 ≤ (Li-O1*Li-O2*Li-O3) ≤ 9.97.

[0109] For lithium in the lattice structure of the LMFP measured by an X-ray diffraction analyzer in the above equation 2, when the bond distances (Å) with oxygen of different axial directions are denoted as Li-O1, Li-O2, and Li-O3, (Li-O1*Li-O2*Li-O3) means the product of Li-O1, Li-O2, and Li-O3.

[0110] Specifically, differences in electrochemical performance occur because the Li migration rate varies depending on the bond distance between Li and O.

[0111] The longer the Li-O bond distance, the more smoothly Li ions are released due to lower bond energy. Conversely, as the PO bond distance decreases, structural stability increases.

[0112] The bonding distance of these Li-O is influenced by the average particle size (D50) (nm) of the slurry immediately after grinding is finished during the process of manufacturing the cathode active material. And depending on the average particle size of the slurry, the crystallization and average crystal size of the cathode active material can be controlled.

[0113] As the average particle size of the slurry decreases, crystallization occurs more effectively, so strong PO bonds within the cathode active material become more strongly bonded, and the PO bond distance becomes shorter.

[0114] Assuming the unit cell volume is the same, as crystallization increases, O, which is relatively lighter than P, moves toward P, shortening the bond distance of PO and causing the volume of the LiO6 octahedron to increase.

[0115] Therefore, as crystallization increases, the Li-O bond distance lengthens and the Li-O bond becomes relatively weaker, so the ionic conductivity increases.

[0116] In this regard, with respect to lithium in the lattice structure of the positive electrode active material, when the bonding distances with oxygen of different axial directions are denoted as Li-O1, Li-O2, and Li-O3, each of Li-O1, Li-O2, and Li-O3 may be 2.2 Å or less, and preferably 2.0 to 2.2 Å.

[0117] Li-O1 can be 2.193 to 2.2 Å, Li-O2 can be 2.099 to 2.2 Å, and Li-O3 can be 2.158 to 2.2 Å.

[0118] Specifically, Li-O1 can be 2.193 to 2.197 Å, Li-O2 can be 2.099 to 2.102 Å, and Li-O3 can be 2.158 to 2.162 Å.

[0119] In Equation 2, (Li-O1*Li-O2*Li-O3) can be measured as follows.

[0120] After measuring the diffraction pattern with the scan range (10 ~ 80˚) and scan speed (2.5˚ / min) of the X-ray diffraction analyzer (Rigaku), a precise analysis of the crystal structure was performed using the Rigaku-SmartLab Studio II program.

[0121] The function model for fitting used the FP (Fundamental parameter) method.

[0122] Through the atomic positions of the analysis results, the distance between Li-O within the LiO6 octahedron was analyzed with a confidence of Rwp 2.5 or less and S value 2 or less.

[0123] As explained above, the crystallization and average crystal size of the anode active material can be controlled according to the average particle size of the slurry immediately after grinding is finished.

[0124] The average particle size (D50) of the LMFP slurry can be 100 to 240 nm, preferably 150 to 230 nm, and more preferably 180 to 210 nm.

[0125] And the average crystal size of the positive active material may be 70 to 110 nm, preferably 80 to 110 nm, and more preferably 90 to 108 nm.

[0126] By satisfying an average crystal size of 70 to 110 nm of the positive active material, the electrochemical reaction is enhanced by the high surface area of ​​the crystal, and the initial discharge capacity can be 150 mAh / g or more.

[0127] The positive active material according to the present invention is LiMn a Fe bIt includes lithium iron manganese phosphate (LMFP) represented by PO4(a + b = 1, a > 0, b > 0).

[0128] LMFP has a secondary particle form formed by the aggregation of multiple primary particles.

[0129] In the present invention, "primary particle" refers to a minimum particle unit that is distinguished as a single mass when the cross-section of the positive active material is observed through a scanning electron microscope (SEM), and may consist of a single crystal grain or a plurality of crystal grains.

[0130] Here, "grain" refers to a region in which atoms within a primary particle form a lattice structure in a specific direction.

[0131] The above "secondary particles" refer to aggregates formed by the aggregation of tens to hundreds of primary particles through physical or chemical bonding between primary particles without an intentional aggregation or assembly process of the primary particles, i.e., secondary structures.

[0132] LiMn a Fe b In the LMFP represented by PO4(a + b = 1), a > 0 and b > 0 may be possible, and preferably a ≥ 0.4 and b ≥ 0.4.

[0133] Here, the molar ratio of Mn to Fe can satisfy approximately 0.5 : 0.5 to 0.6 : 0.4.

[0134] By satisfying a molar ratio of Mn to Fe of approximately 0.5:0.5 to 0.6:0.4, the theoretical energy density is further improved. If the molar ratio of Mn is too low, the energy density is not improved. Conversely, if the molar ratio of Mn is too high, the stability of the lithium secondary battery is reduced, and quality problems may occur.

[0135] The positive active material may further include a dopant to control the average crystal size.

[0136] The above dopant may include one or more of Al, Zr, Nb, Mo, W, Ti, Ce, Mg, B, Y, P, V, and Sr, and preferably may further include a Ti doping element.

[0137] By including additional doping elements in the cathode active material, high-temperature lifespan and thermal stability can be further improved.

[0138] In addition, it is desirable to control the dopant content to control the average crystal size.

[0139] As the dopant content increases, crystal growth is inhibited, which can result in a smaller crystal size. However, if too much is overdoped, even if crystal growth is inhibited, it may block the movement of Li ions and electrons, which can have an adverse effect on performance.

[0140] In this regard, the positive electrode active material of the present invention may further include 0.5 to 1.5 mol% of a dopant with respect to 100 mol% of the total, and preferably 0.5 to 1.0 mol%.

[0141] By satisfying a dopant content of 0.5 to 1.5 mol%, it has an advantageous effect in exhibiting an initial discharge capacity of 150 mAh / g or more.

[0142] In order to improve the electrical conductivity of the LMFP positive electrode active material, the present invention may further include a carbon layer coated on the surface of the LMFP.

[0143] The carbon to be coated may include one or more of glucose, sucrose, fructose, lactose, maltose, graphite, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, a material having a crystal structure including graphene, and a material having a crystal structure including graphite, and preferably may include glucose.

[0144] It is desirable to control the carbon content to control the electrical conductivity and average crystal size of the positive electrode active material.

[0145] As carbon content increases, crystal growth is inhibited and conductivity tends to increase.

[0146] However, if the carbon content becomes too high, the excessively large specific surface area (BET) can actually become a factor that hinders electrical flow.

[0147] In this regard, the carbon content of the carbon layer of the cathode active material may be 1 to 3 weight% with respect to 100 weight% of the total, and preferably 1.5 to 2.0 weight%.

[0148] By satisfying a carbon content of 1 to 3 weight percent in the carbon layer, carbon is dispersed at a uniform concentration in the positive electrode active material, thereby improving the electrical conductivity of the lithium secondary battery, reducing the average crystal size, and further improving the initial discharge capacity at room temperature.

[0149] Method for manufacturing positive electrode active material

[0150] The method for manufacturing a positive electrode active material according to the present invention is characterized by comprising the steps of preparing and grinding an LMFP precursor, spray-drying the slurry obtained by grinding, and calcining the powder obtained by spray-drying to manufacture a positive electrode active material.

[0151] The positive electrode active material manufactured according to the manufacturing method of the present invention comprises an LMFP formed from the above precursors, and the LMFP is LiMn a Fe b It is represented as PO4(a + b = 1, a > 0, b > 0).

[0152] Step of preparing and grinding the LMFP precursor

[0153] As an LMFP precursor, a lithium precursor, a phosphorus precursor, an iron precursor, and a manganese precursor can be mixed and milled for 2 to 5 hours, preferably for 4 to 5 hours. By satisfying a grinding time of 2 to 5 hours, the average particle size (D50) of the slurry immediately after grinding is nanoscaled, which has the effect of increasing crystallization. When crystallization is improved, the Li-O bond distance increases, and ion conductivity can be improved. As a result, there is an effect of improving the initial discharge capacity of the lithium secondary battery.

[0154] The lithium (Li) precursor may include one or more of Li2CO3, Li(OH), Li(OH)·H2O, LiNO3, and LiH2PO4, and preferably may include one or more of Li2CO3 and LiH2PO4.

[0155] The phosphorus (P) precursor may include one or more of lithium dihydrogen phosphate (LiH2PO4) and FePO4. The lithium dihydrogen phosphate (LiH2PO4) can be obtained by reacting lithium phosphate (Li3PO4), an intermediate product, with a phosphoric acid (H3PO4) solution during the process of producing lithium carbonate or lithium hydroxide in a salt lake.

[0156] Iron (Fe) precursors may include FePO4, etc.

[0157] Manganese (Mn) precursors may include Mn3O4, etc.

[0158] Grinding can be performed using beads and wet milling methods.

[0159] The bead size may be 0.3 to 0.5 mm, and preferably 0.3 to 0.4 mm.

[0160] The rotational speed can be performed in the range of 3000 to 3500 rpm / min, and preferably in the range of 3100 to 3500 rpm.

[0161] By satisfying the above bead size and rotation speed, the average particle size of the slurry can be controlled, and as a result, there is an advantageous effect in satisfying the intensity of the (101) plane peak where the Li ion is located and the Li-O bond distance.

[0162] In addition, as the positive electrode active material satisfies this composition, the lithium secondary battery containing the positive electrode active material can secure an excellent initial discharge capacity.

[0163] In addition, the average particle size of the secondary particles constituting the anode active material and the primary particles constituting the secondary particles can be controlled through grinding using a wet milling method.

[0164] In the present invention, the average particle size (D50) of the LMFP slurry immediately after grinding is a factor that affects the degree of crystallization, and crystallization occurs better as the average particle size (D50) of the slurry becomes nanoscale.

[0165] The smaller the average particle size of the slurry, the more nano-sized particles are formed, and the formed nano-sized particles constitute secondary particles. As the average particle size of the slurry decreases, the surface energy increases due to the large surface area, making it unstable. To lower the high surface energy, the slurry easily combines and reacts at lower temperatures.

[0166] The smaller the average particle size of the slurry, the more contact points between nanoparticles increase during the LMFP synthesis process, and the structure synthesis process and crystallization are facilitated by smooth mass transport due to the low radius of curvature of the contact points between nanoparticles.

[0167] As more crystal nuclei are generated to lower the high surface energy of the slurry, growth is inhibited due to the many crystal nuclei, allowing the final average crystal size to be controlled to be small. In other words, the degree of crystallization can be improved by lowering the average particle size of the slurry.

[0168] However, if the average crystal size becomes too small, reactivity increases excessively due to the high surface area of ​​the crystal. As a result, there is a possibility that undesirable side reactions may occur in addition to the desired reaction, which can lead to structural instability of the cathode active material.

[0169] In addition, since an excessively high surface area of ​​the crystal can increase contact resistance between particles and actually have an adverse effect on conductivity, it is necessary to control the average crystal size.

[0170] Therefore, the inventors selected an average crystal size that allows electrochemical reactions to occur more actively due to the high surface area of ​​the crystal while maintaining the structural stability of the positive electrode active material.

[0171] In this regard, the average particle size (D50) of the LMFP slurry can be 100 to 240 nm.

[0172] And the average crystal size of the positive active material can be 70 to 110 nm.

[0173] To improve the electrical conductivity of the lithium secondary battery and control the average crystal size, 10% by weight or less of a carbon precursor may be further mixed with the LMFP precursor based on 100% by weight of the total, and preferably 3 to 8% by weight of a carbon precursor may be further mixed.

[0174] When the carbon precursor is mixed at 10% by weight or less, the carbon content of the carbon layer of the cathode active material can satisfy 3% by weight or less.

[0175] The carbon precursor may include one or more of glucose, sucrose, fructose, lactose, maltose, graphite, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, a material having a crystal structure including graphene, and a material having a crystal structure including graphite, and preferably may include glucose.

[0176] In addition, 0.5 to 1.5 mol% of dopant can be further mixed with respect to the total 100 mol%.

[0177] The dopant may include one or more of Al, Zr, Nb, Mo, W, Ti, Ce, Mg, B, Y, P, V, and Sr, and preferably may include Ti. In the process of manufacturing the cathode active material, mixing in additional doping elements is advantageous for controlling the average crystal size and can further improve high-temperature life and thermal stability.

[0178] In addition, one or more dispersants selected from citric acid, fumaric acid, adipic acid, succinic acid, tartaric acid, glutaric acid, maleic acid, oxalic acid, malonic acid, and ascorbic acid may be further mixed, and preferably, citric acid may be further mixed.

[0179] In the process of manufacturing the positive electrode active material, by further mixing in a dispersant, the precursors in the slurry are uniformly dispersed, which is advantageous for manufacturing high-quality olivine-based LMFP positive electrode active materials for lithium secondary batteries.

[0180] With respect to 100% by weight of the total, 5% by weight or less of a dispersant may be mixed, but is not limited thereto.

[0181] Step of spray-drying the slurry obtained by grinding

[0182] In the step of spray-drying the slurry obtained by grinding, spray drying can be performed using a spray dryer.

[0183] The spray pressure of the spray dryer can be 0.5 to 2 bar, and preferably 1 to 1.5 bar.

[0184] The temperature of the main chamber may be 200 to 300°C, and preferably 220 to 260°C.

[0185] The discharge temperature of the spray dryer can be set to 80 to 160°C, and preferably to 100 to 130°C.

[0186] By setting the spray pressure, main chamber temperature, and outlet temperature of the spray dryer as described above, spherical powder can be obtained from the slurry through spray drying.

[0187] The above spherical powder may be a secondary particle constituting the LMFP.

[0188] Step of manufacturing an anode active material by calcining powder obtained by spray drying

[0189] The powder obtained by spray drying is loaded into a kiln. Then, by firing under high temperature conditions for a predetermined time in an atmosphere where an inert gas is continuously supplied, a positive electrode active material for a lithium secondary battery with a carbon layer coated on the surface of the LMFP can be manufactured.

[0190] As the calcination temperature decreases, crystal growth slows down and the crystal size becomes smaller. However, since low calcination temperatures adversely affect the synthesis and crystallization of the cathode active material, it is important to control the average crystal size by adjusting the calcination temperature.

[0191] Calcination can be performed in an inert atmosphere at 630 to 700°C for 1 to 10 hours, and preferably at 650 to 690°C for 3 to 8 hours.

[0192] By satisfying a calcination temperature and calcination time of 630 to 700°C for 1 to 10 hours, the average crystal size can be controlled to 70 to 110 nm, which is advantageous for demonstrating the performance of the cathode active material.

[0193] Lithium secondary battery

[0194] The lithium secondary battery according to the present invention is characterized by comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises the aforementioned positive electrode active material.

[0195] The 0.1C discharge capacity of the lithium secondary battery may be 150 mAh / g or more, and preferably 150 to 160 mAh / g.

[0196] anode

[0197] A lithium secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator, and among these, the positive electrode includes a positive electrode material comprising a positive electrode active material, a conductive material, and a binder, and a current collector.

[0198] The anode according to the present invention comprises a current collector and an anode material disposed on at least one surface of the current collector and comprising the aforementioned anode active material.

[0199] A detailed explanation regarding the positive electrode active material will be omitted.

[0200] The cathode material acts as a lithium source in lithium-ion batteries and is a key material that determines battery capacity and average voltage.

[0201] The cathode material may include a binder and a conductive material.

[0202] The above binder serves to effectively bond the positive active material particles to each other and also to effectively bond the positive active material to the current collector.

[0203] Representative examples of binders include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing 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.

[0204] 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 carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or conductive materials comprising mixtures thereof.

[0205] The above anode is manufactured by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and applying this composition to a current collector.

[0206] Since such an electrode manufacturing method is widely known in the art, a detailed description thereof will be omitted in this specification. The solvent may include N-methylpyrrolidone, but is not limited thereto.

[0207] The above current collector may be, for example, made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc.

[0208] cathode

[0209] The above cathode includes a current collector and a cathode material formed on the current collector, and the cathode material may include a cathode active material.

[0210] The above negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0211] The material capable of reversibly intercalating / deintercalating the above lithium ions may be, for example, a carbon material, and any carbon-based negative electrode active material generally used in the above lithium secondary battery may be used.

[0212] For example, carbon-based cathode active materials can use crystalline carbon, amorphous carbon, or a combination thereof.

[0213] As the above lithium metal alloy, an alloy of a metal selected from the group consisting of lithium, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0214] Examples of materials capable of doping and dedoping the above lithium include Si, SiOx (0 < x < 2), Si-Y alloy (wherein Y is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO2, Sn-Y (wherein Y is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn).

[0215] Examples of the above transition metal oxides include vanadium oxide, lithium vanadium oxide, etc.

[0216] The above cathode material also includes a binder and may optionally further include a conductive material.

[0217] The above binder can serve to effectively attach the negative electrode active material particles to each other and also effectively attach the negative electrode active material to the current collector.

[0218] The above conductive material is used to impart conductivity to the electrode, and in the battery being constructed, any electronically conductive material that does not cause chemical changes can be used.

[0219] For example, the above current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0220] The above-mentioned cathode and anode may be manufactured by preparing an active material composition by mixing an active material, a conductive material, and a binder in a solvent, and applying the composition to a current collector, and the present invention does not limit the method of manufacturing the electrodes.

[0221] The above solvent may include N-methylpyrrolidone, but is not limited thereto.

[0222] electrolytes

[0223] The above electrolyte may be a non-aqueous electrolyte or a solid electrolyte, and may be used in which a lithium salt is dissolved.

[0224] The above-mentioned non-aqueous electrolyte may include an organic solvent, and the above-mentioned non-aqueous organic solvent may serve as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0225] The above organic solvent may be, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate; esters such as methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone; ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,2-dioxane, 2-methyltetrahydrofuran; nitriles such as acetonitrile; amides such as dimethylformamide. These may be used individually or in combination.

[0226] In particular, a mixed solvent of cyclic carbonates and chain carbonates can be preferably used.

[0227] In addition, as an electrolyte, a gel-type polymer electrolyte in which an electrolyte solution is impregnated into a polymer electrolyte such as polyethylene oxide or polyacrylonitrile, or an inorganic solid electrolyte such as LiI or Li3N, is possible.

[0228] The above lithium salt is a material that is dissolved in an organic solvent and acts as a source of lithium ions within the battery, enabling the operation of a basic lithium secondary battery and facilitating the movement of lithium ions between the positive and negative electrodes.

[0229] The above lithium salt may be any commonly used in the art without limitation, provided that it does not impede the purpose of the present invention.

[0230] For example, the lithium salt may be one selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiSbF6, LiAlO4, LiAlCl4, LiCl, and LiI.

[0231] Depending on the type of the above lithium secondary battery, a separator may be present between the positive and negative electrodes.

[0232] As such separators, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof may be used, and of course, mixed multilayer films such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, and polypropylene / polyethylene / polypropylene three-layer separators may be used.

[0233] Lithium secondary batteries can be classified into lithium-ion batteries, lithium-ion polymer batteries, and lithium polymer batteries depending on the type of separator and electrolyte used; they can be classified into cylindrical, prismatic, coin, and pouch types depending on their shape; and they can be divided into bulk and thin-film types depending on their size.

[0234] The present invention does not limit the structure and manufacturing method of the battery.

[0235] As such, specific embodiments of the positive electrode active material and the lithium secondary battery using it are as follows.

[0236] 1. Preparation of positive electrode active material

[0237] Manufacturing method for each sample in Tables 1 and 2 below

[0238] Wet Bead Mill (WM): FePO4102.2g, Mn3O477.5g, LiH2PO4105.1g, Li2CO326.9g, TiO20.7g (0.5mol%) as dopant, glucose (C6H2) as carbon source 12 25.8 g (7 wt%) of O6 and 4.8 g of citric acid (C6H8O7) as a dispersant were mixed with 800 g of ultrapure water and ground at 3000-3500 rpm / min for 2 to 5 hours under the bead mill conditions listed in Table 2. (0.3-0.5 mm zirconia beads used. NETZSCH MINISERIES model)

[0239] Spray Drying (SD): The mixed slurry obtained after wet bead milling was spray-dried using a spray dryer. (Spray pressure: 1.5 bar, main chamber temperature: 250℃, outlet temperature: 110℃)

[0240] Calcination (High-temperature heat treatment): 30g of SD specimens were placed in graphite saga and calcined under a nitrogen atmosphere. (Calcination temperature: 670°C, calcination holding time: 6 hours, heating rate: 5°C / min, nitrogen flow rate: 1.0 L / min, pre-calcination furnace nitrogen flow rate: 1.5 L / min, nitrogen purging for 1 hour 30 minutes (for oxygen removal))

[0241] In Table 1 below, "C (weight%) after firing" is the carbon content (weight%) of the carbon coating layer after firing.

[0242] [Table 1]

[0243]

[0244] In Table 2 below, "WM time (min)" is the grinding time of the wet bead mill.

[0245] [Table 2]

[0246]

[0247] 2. Method for evaluating physical properties and results

[0248] 1) Electrochemical (coin half-cell) electrode coating: An electrode slurry was prepared by adding 4.3g of NMP to 4.5g of LMFP, 0.25g of SuperP (conductive carbon black), and 3.125g of PVDF 8wt.% (KF7208, a solution of binder dissolved in NMP). After electrode coating using a doctor blade, the electrodes were dried at 130°C for 2 hours and rolled to a height of 0.2 mm. (Specifications of fabricated coin half-cell electrodes: mass loading - 10~11 mg / cm² 2 ).

[0249] 2. Electrochemical C-rate capacity evaluation conditions: 24 hours of aging immediately after cell fabrication (temperature 25℃), one formation cycle (2.5-4.4V) with 0.1 C charge / discharge, a fixed charge rate of 0.1C, and one measurement each at discharge rates of 0.1, 0.33, 1, 2, 5, and 10 C (2.5-4.4V), using CC-CV charge mode (Charge step condition: fixed at 0.1C, 0.05 C cut-off current). A 20-minute rest was performed immediately after the charge and discharge steps.

[0250] 3. Measurement of average particle size of slurry (D50(WM)): 0.02 g of LMFP slurry after wet bead milling was measured using a Malvern particle size meter with 1 ml of IGEPAL 1.0 wt.% dispersant.

[0251] 4. Average Crystal Size of Cathode Active Material: After measuring the diffraction pattern using an X-ray diffraction analyzer (Rigaku), a precise analysis of the crystal structure was performed using the Rigaku-SmartLab Studio II program. To analyze the crystal information regarding the entire diffraction pattern, the Fundamental Parameter (FP) method was used as the functional model, and the average crystal size was calculated by assuming spherical particles. (XRD measurement conditions: Scan range (10⁻⁸⁰) o ), Scan speed(2.5 o / min) / Analysis was performed with a reliability of Rwp 2.5 or less and an S value 2 or less).

[0252] 5. Li-O Bond Distance (Å): After measuring the diffraction pattern using an X-ray diffraction analyzer (Rigaku), a precise analysis of the crystal structure was performed using the Rigaku-SmartLab Studio II program. The Fundamental Parameter (FP) method was used as the functional model for fitting. The distances between Li-O atoms (Li-O1, Li-O2, Li-O3) within the LiO6 octahedron were analyzed based on the atomic positions in the analysis results (XRD measurement conditions: Scan range (10-80 o ), Scan speed(2.5 o / min) / Analysis was performed with a reliability of Rwp 2.5 or less and an S value 2 or less).

[0253] 6. (101) Normalized intensity: After measuring the diffraction pattern using an X-ray diffraction analyzer (Rigaku), the diffraction data for each plane was analyzed by fitting with the Pseudo-Voigt function. Then, assuming the intensity value of the highest peak was 100, the peak value of plane (101) was converted to calculate Normal. I (XRD measurement conditions: Scan range(10-80 o ), Scan speed(2.5 o / min)).

[0254] [Table 3]

[0255]

[0256] [Table 4]

[0257]

[0258] Examples 1 and 2 show that the relative peak intensity of the (101) plane of the present invention is high and the Li-O bond distance is increased, which means that crystallization and ionic conductivity are high.

[0259] Examples 1 and 2 satisfied Norm.I (101) ≥ 64.6 of Equation 1, so the initial discharge capacity of the lithium secondary battery at room temperature was 150 mAh / g or more.

[0260] Comparative Examples 1 to 4 showed an average crystal size of 114 nm or more of the anode active material, and compared to Examples 1 and 2, the relative peak intensity of the (101) plane was lower and the Li-O bond distance was shorter.

[0261] These results indicate that crystallization and ionic conductivity are low, and the Norm. I (101) ≥ 64.6 of Equation 1 was not satisfied. Accordingly, the initial discharge capacity of the lithium secondary battery at room temperature was significantly low.

[0262] From these results, it can be seen that the Norm.I (101) and Li-O bond distance of the LMFP positive electrode active material have a significant effect on the initial discharge capacity of the lithium secondary battery at room temperature.

[0263] Although the present invention has been described above with reference to the exemplary embodiments, the present invention is not limited by the embodiments disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while explaining the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. LiMn a Fe b Includes an LMFP represented by PO4(a + b = 1, a > 0, b > 0), and A positive active material satisfying the following relationship 1. [Relationship 1] Norm.I (101) ≥ 64.6 In the above equation 1, Norm.I (101) is [(101) plane peak intensity / (311) plane peak intensity] × 100, and the (311) plane peak intensity is the intensity of the strongest peak of the LMFP measured by an X-ray diffraction analyzer.

2. In Paragraph 1, A positive active material that further satisfies the following relationship 2. [Relationship 2] (Li-O1*Li-O2*Li-O3) ≥ 9.95 For lithium in the lattice structure of the LMFP measured by an X-ray diffraction analyzer in the above equation 2, when the bond distances (Å) with oxygen of different axial directions are denoted as Li-O1, Li-O2, and Li-O3, (Li-O1*Li-O2*Li-O3) means the product of Li-O1, Li-O2, and Li-O3.

3. In Paragraph 2, The above Li-O1 is 2.193 to 2.2 Å, and The above Li-O2 is 2.099 to 2.2 Å, and The above Li-O3 is a positive active material having a diameter of 2.158 to 2.2 Å.

4. In Paragraph 1, A positive active material with an average crystal size of 70 to 110 nm.

5. In Paragraph 1, A positive active material comprising 0.5 to 1.5 mol% of a dopant based on 100 mol% of the total.

6. In Paragraph 5, The above dopant is a positive active material comprising one or more of Al, Zr, Nb, Mo, W, Ti, Ce, Mg, B, Y, P, V, and Sr.

7. In Paragraph 1, It further includes a carbon layer coated on the surface of the above LMFP, and A positive electrode active material having a carbon content of 1 to 3 weight percent based on 100 weight percent of the total carbon layer.

8. Anode comprising the positive active material of any one of paragraphs 1 to 7; cathode; and A lithium secondary battery containing an electrolyte. 9.(a) A step of preparing and grinding an LMFP precursor; (b) a step of spray-drying the slurry obtained by grinding above; and (c) a step of preparing an anode active material by calcining the powder obtained by spray drying above; comprising, The above LMFP is LiMn a Fe b It is represented as PO4(a + b = 1, a > 0, b > 0), and A method for manufacturing a positive electrode active material satisfying the following relationship 1. [Relationship 1] Norm.I (101) ≥ 64.6 In the above equation 1, Norm.I (101) is [(101) plane peak intensity / (311) plane peak intensity] × 100, and the (311) plane peak intensity is the intensity of the strongest peak of the LMFP measured by an X-ray diffraction analyzer.

10. In Paragraph 9, A method for manufacturing a positive electrode active material that further satisfies the following relationship 2. [Relationship 2] (Li-O1*Li-O2*Li-O3) ≥ 9.95 For lithium in the lattice structure of the LMFP measured by an X-ray diffraction analyzer in the above equation 2, when the bond distances (Å) with oxygen of different axial directions are denoted as Li-O1, Li-O2, and Li-O3, (Li-O1*Li-O2*Li-O3) means the product of Li-O1, Li-O2, and Li-O3.

11. In Paragraph 9, In step (a) above, the grinding is A method for manufacturing a positive electrode active material using beads having a size of 0.3 to 0.5 mm, performed at a rotational speed of 3000 to 3500 rpm / min.

12. In Paragraph 9, A method for manufacturing a positive electrode active material in which, in step (b) above, the average particle size (D50) of the slurry obtained by grinding is 100 to 240 nm.

13. In Paragraph 9, The step of preparing and grinding the above (a) LMFP precursor A method for manufacturing a positive electrode active material by mixing and milling a lithium precursor, a phosphorus precursor, an iron precursor, and a manganese precursor for 2 to 5 hours.

14. In Paragraph 9, A method for manufacturing a positive electrode active material, wherein, in step (a) above, 10% by weight or less of a carbon precursor is further mixed with the LMFP precursor based on 100% by weight of the total.

15. In Paragraph 14, A method for manufacturing a positive electrode active material comprising, in step (a) above, one or more of the following: a carbon precursor, glucose, sucrose, fructose, lactose, maltose, graphite, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, a material having a crystal structure including graphene, and a material having a crystal structure including graphite.

16. In Paragraph 9, A method for manufacturing a positive electrode active material, wherein, in step (a) above, 0.5 to 1.5 mol% of a dopant is further mixed with respect to 100 mol% of the total.

17. In Paragraph 16, A method for manufacturing a positive active material comprising, in step (a) above, one or more of the dopants Al, Zr, Nb, Mo, W, Ti, Ce, Mg, B, Y, P, V, and Sr.

18. In Paragraph 9, A method for manufacturing a positive electrode active material in step (c) above, wherein calcination is performed in an inert atmosphere at 630 to 700°C.

19. In Paragraph 9, A method for manufacturing an anode active material by further mixing one or more dispersants selected from citric acid, fumaric acid, adipic acid, succinic acid, tartaric acid, glutaric acid, maleic acid, oxalic acid, malonic acid, and ascorbic acid in step (a) above.

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