Method for preparing cathode active material precursor, cathode active material precursor, and method for preparing cathode active material by using cathode active material precursor

Abstract

The present invention relates to a method for preparing a cathode active material precursor, a cathode active material precursor, and a method for preparing a cathode active material by using the cathode active material precursor, the precursor having a controlled shape and physical properties so as to have a specific surface area and an internal density that can contribute to an improvement in capacity characteristics and rate characteristics of a cathode active material.

Description

Method for manufacturing a positive electrode active material precursor, a positive electrode active material precursor, and a method for manufacturing a positive electrode active material using a positive electrode active material precursor

[0001] The present invention relates to a method for manufacturing a positive active material precursor that achieves a specific surface area and internal density capable of contributing to the improvement of the capacity and rate characteristics of a positive active material by controlling the shape and physical properties of the precursor, a positive active material precursor, and a method for manufacturing a positive active material using the positive active material precursor.

[0002]

[0003] Batteries store electricity by using materials capable of electrochemical reactions at the positive and negative electrodes. A representative example of such a battery is the lithium secondary battery, which stores electrical energy based on the difference in chemical potential when lithium ions are intercalated or deintercalated at the positive and negative electrodes.

[0004] The above lithium secondary battery is manufactured by using materials capable of reversible intercalation / deintercalation of lithium ions as positive and negative active materials, and by filling an organic electrolyte or a polymer electrolyte between the positive and negative electrodes.

[0005] Lithium composite oxides are representative materials used as positive electrode active materials for lithium secondary batteries. Examples of such lithium composite oxides include LiCoO2, LiMn2O4, LiNiO2, LiMnO2, or oxides complexed with Ni, Co, Mn, or Al.

[0006] Among the aforementioned cathode active materials, LiCoO2 is the most widely used due to its excellent lifespan characteristics and charge / discharge efficiency; however, it has the disadvantage of limited price competitiveness because it is expensive due to the resource limitations of cobalt used as a raw material.

[0007] Lithium manganese oxides such as LiMnO2 and LiMn2O4 have the advantages of excellent thermal stability and low cost, but they have problems such as low capacity and poor high-temperature performance. In addition, LiNiO2-based cathode active materials exhibit high discharge capacity battery characteristics, but synthesis is difficult due to cation mixing between Li and transition metals, and consequently, there are significant problems with rate characteristics.

[0008] In addition, a large amount of Li byproducts is generated depending on the degree of intensification of this cation mixing. Most of the above Li byproducts consist of LiOH and Li2CO3, and can cause gelation during the manufacture of anode paste or generate gas during repeated charging and discharging after electrode manufacturing. Furthermore, residual Li2CO3 among the above Li byproducts acts as a cause of reduced lifespan characteristics by increasing the swelling phenomenon of the cell.

[0009] Various candidate materials are being proposed to compensate for the shortcomings of these existing cathode active materials.

[0010] For example, research is underway to use lithium-excess lithium manganese oxides, which contain an excess of Mn among the transition metals and have a lithium content greater than the sum of the transition metal contents, as cathode active materials for lithium secondary batteries. Such lithium-excess lithium manganese oxides are also referred to as overlithiated layered oxides (OLO).

[0011] Although the above OLO theoretically has the advantage of being able to exhibit high capacity under high-voltage operating environments, in reality, due to the excess Mn contained in the oxide, it has a relatively low electrical conductivity, and consequently, the rate characteristics of lithium secondary batteries using OLO are low. As such, when rate characteristics are low, problems may arise in which the charge / discharge capacity and lifespan efficiency (cycle capacity retention rate) of the lithium secondary battery decrease during cycling.

[0012] Research on modifying the composition of OLO to address the aforementioned problems has been ongoing, but these attempts have not yet reached the level of commercialization.

[0013]

[0014] In the lithium secondary battery market, the growth of lithium secondary batteries for electric vehicles is acting as a driving force, and accordingly, the demand for cathode active materials used in lithium secondary batteries is also continuously increasing.

[0015] For example, in the past, lithium secondary batteries using lithium iron phosphate (LFP) were mainly used for the sake of ensuring safety, but recently, there has been a growing trend of using nickel-based lithium composite oxides, which have a higher energy capacity per unit weight compared to LFP.

[0016] In addition, nickel-based lithium composite oxides, which are primarily used as cathode active materials for high-capacity lithium secondary batteries, necessarily utilize ternary metal elements such as nickel, cobalt, and manganese or nickel, cobalt, and aluminum. However, since the supply of cobalt is unstable and it is excessively expensive compared to other raw materials, there is a need for cathode active materials with new compositions that can reduce the cobalt content or exclude cobalt.

[0017] Considering all these circumstances, while lithium-excess lithium manganese-based oxides can meet the aforementioned market expectations, there are still limitations in that the lithium manganese-based oxides lack electrochemical properties or stability to replace high-Ni type cathode active materials, such as commercially available ternary lithium composite oxides of nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) compositions.

[0018] For example, it has been previously mentioned that OLO has the disadvantage of having low charge / discharge capacity and rate characteristics due to the material characteristics (including excess lithium and manganese).

[0019] Therefore, to improve the poor electrochemical properties of OLO, one can consider increasing the particle size. However, since the particles constituting the precursor of OLO generally grow mainly as thick plate-like particles, increasing the size of the secondary particles increases the internal density, but this may lead to a problem where performance deteriorates due to low conductivity.

[0020] However, the inventors have confirmed that the shape and physical properties of the precursor can be controlled according to the synthesis (co-precipitation reaction) conditions of the lithium manganese-based oxide precursor, and that the capacity and rate characteristics of the cathode active material can be improved when a cathode active material is manufactured using a precursor that has achieved an appropriate specific surface area and internal density.

[0021] Accordingly, the present invention aims to provide a method for manufacturing a cathode active material precursor capable of controlling the shape and physical properties of the reaction product precursor by adjusting the synthesis (co-precipitation reaction) conditions of the lithium manganese-based oxide precursor, thereby enabling the realization of an appropriate specific surface area and internal density of the precursor.

[0022] In addition, the present invention aims to provide a positive electrode active material precursor in which the surface shape of the primary particles exposed on the surface has a major axis and a minor axis, and appropriate specific surface area and internal density are realized, as manufactured by the manufacturing method defined herein.

[0023] In addition, the present invention aims to provide an anode active material precursor having an appropriate particle size distribution in which fine particle formation is suppressed or mitigated as it is manufactured by the manufacturing method defined herein.

[0024] In addition, the present invention aims to provide a method for manufacturing a positive electrode active material using the above-mentioned positive electrode active material precursor.

[0025] 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.

[0026]

[0027] To solve the aforementioned technical problem, the present invention provides a method for manufacturing a positive electrode active material precursor that achieves an appropriate specific surface area and internal density by controlling the shape and physical properties of the precursor as described below, a positive electrode active material precursor, and a method for manufacturing a positive electrode active material using the positive electrode active material precursor.

[0028] (1) The present invention provides a method for manufacturing a cathode active material precursor, comprising the step of introducing an aqueous transition metal solution, an ammonium cation complex forming agent, and a basic aqueous solution into a reactor and co-precipitating them under conditions of pH greater than 8.0 and pH less than 10.0 to form a transition metal hydroxide precursor, wherein the content of manganese (mol%) in the aqueous transition metal solution is greater than the content of nickel (mol%).

[0029] (2) The present invention provides a method for manufacturing an anode active material precursor according to (1), wherein the aqueous solution of the transition metal further comprises one or more elements selected from alkali metals, alkaline earth metals, transition metals other than nickel and manganese, post-transition metals, and metalloids.

[0030] (3) The present invention provides a method for manufacturing a positive electrode active material precursor in any one of (1) and (2), wherein the transition metal aqueous solution comprises 50 mol% or more of manganese relative to the total molar amount of the transition metal.

[0031] (4) The present invention provides a method for manufacturing a positive electrode active material precursor in any one of (1) to (3), wherein the co-precipitation reaction is performed at a pH of 8.5 to 9.5.

[0032] (5) The present invention provides a method for manufacturing a positive electrode active material precursor in any one of (1) to (4), wherein the co-precipitation reaction is performed under a non-oxidizing atmosphere or an oxidizing atmosphere.

[0033] (6) The present invention provides a method for manufacturing a positive electrode active material precursor in any one of (1) to (5), wherein the co-precipitation reaction is performed under an oxidizing atmosphere containing 0.5 volume% or more and less than 6.0 volume% of oxygen.

[0034] (7) The present invention provides a method for manufacturing a positive electrode active material precursor in any one of (1) to (6), wherein the co-precipitation reaction is performed at a temperature of 50°C or higher and less than 80°C.

[0035] (8) The present invention provides a positive electrode active material precursor comprising a transition metal hydroxide represented by the following chemical formula 1, wherein the transition metal hydroxide has a secondary particle form in which a plurality of primary particles are aggregated, and the surface shape of the primary particles exposed on the surface of the transition metal hydroxide, as observed from a surface SEM image of the transition metal hydroxide, has a long axis and a short axis.

[0036] [Chemical Formula 1]

[0037] [Ni b Co c Mn d M1 e ](OH)2

[0038] In the above chemical formula 1,

[0039] M1 is at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge and Nd, and

[0040] 0≤b<0.5, 0≤c≤0.2, 0.5≤d<0.8, 0 <e≤0.1, b+c+d+e=1이다.

[0041] (9) The present invention provides a positive electrode active material precursor according to (8), wherein the average value of the ratio of the major axis length to the minor axis length (major axis length / minor axis length) of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is 1.5 or more and 25.0 or less.

[0042] (10) The present invention provides a positive electrode active material precursor in which, in any one of (8) and (9), the average value of the short length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is 30 nm or more and 270 nm or less.

[0043] (11) The present invention provides a positive electrode active material precursor in any one of (8) to (10), wherein the average value of the major axis length of the surface shape of the primary particles exposed to the surface of the transition metal hydroxide is 400 nm or more and 2500 nm or less.

[0044] (12) The present invention, in any one of (8) to (11), wherein the average particle size (D) of the transition metal hydroxide 50 The particle size is 5.0 μm to 24.0 μm, and the span value for the particle size of the transition metal hydroxide calculated by the following Equation 1 is 0.90 or less, thereby providing a positive electrode active material precursor.

[0045] [Equation 1]

[0046] span value = (D 90 -D 10 ) / D 50

[0047] (13) The present invention, in any one of (8) to (12), has a BET specific surface area of ​​8.0 m² as measured by the nitrogen adsorption method. 2 / g to 28.0m 2 Provides a positive electrode active material precursor with a g / g content.

[0048] (14) The present invention provides a positive active material precursor in any one of (8) to (13), wherein the ratio (a / b) of the diffraction peak intensity (a) appearing in the 2θ=11.8±1° region to the diffraction peak intensity (b) appearing in the 2θ=18.6±1° region when analyzing the X-ray diffraction spectrum of the positive active material precursor is 0.25 or less.

[0049] (15) The present invention provides a method for manufacturing an anode active material comprising: a step of forming an oxide precursor by first heat treating an anode active material precursor according to any one of (8) to (14); and a step of mixing the oxide precursor with a lithium raw material and then performing a second heat treatment to form a lithium manganese-based oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group exist as a solid solution.

[0050]

[0051] According to the present invention, it is possible to improve the limitations of existing lithium-excess lithium manganese-based oxides, which have several disadvantages in terms of electrochemical properties and / or stability compared to commercially available ternary lithium composite oxides of nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) compositions.

[0052] Specifically, according to the present invention, the shape and physical properties of the precursor of the lithium manganese-based oxide can be controlled according to the synthesis (co-precipitation reaction) conditions, and through this, improvements in the capacity and rate characteristics of the cathode active material manufactured using the precursor having appropriate specific surface area and internal density can be expected.

[0053] In addition, the cathode active material precursor produced by the manufacturing method defined herein has an appropriate particle size distribution in which fine particle formation is suppressed or mitigated, and by suppressing the formation of impurity phases, it is expected that the capacity and rate characteristics of the cathode active material produced using said precursor can be improved.

[0054] 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.

[0055]

[0056] For convenience, specific terms are defined herein to facilitate a better understanding of the present invention. Unless otherwise defined herein, scientific and technical terms used in this invention shall have the meanings generally understood by those skilled in the art. Furthermore, unless specifically indicated in the context, terms in their singular form shall be understood to include their plural form, and terms in their plural form shall be understood to include their singular form.

[0057]

[0058] The present invention provides a method for manufacturing a positive electrode active material precursor that achieves an appropriate specific surface area and internal density by controlling the shape and physical properties of the precursor, a positive electrode active material precursor, and a method for manufacturing a positive electrode active material using the positive electrode active material precursor. The present invention will be described in more detail below.

[0059]

[0060] Method for manufacturing a positive electrode active material precursor

[0061] According to one aspect of the present invention, a method for manufacturing a positive electrode active material precursor is provided, comprising the step of introducing an aqueous transition metal solution, an ammonium cation complex forming agent, and a basic aqueous solution into a reactor and co-precipitating under conditions of pH greater than 8.0 and pH less than 10.0 to form a transition metal hydroxide precursor.

[0062] The above reactor may be a batch reactor or a continuous reactor, and regardless of the type of reactor, the method for manufacturing a positive electrode active material precursor defined herein may be applied.

[0063] The above transition metal aqueous solution may be prepared by adding a raw material containing a transition metal to deionized water or a mixed solvent containing deionized water, or by mixing an aqueous solution containing a transition metal. The mixed solvent containing deionized water may include an organic solvent (e.g., alcohol, etc.) that is uniformly miscible with water.

[0064] The raw material containing the above transition metal may be a sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide and / or oxyhydroxide containing at least one transition metal.

[0065] The above transition metal aqueous solution may include a nickel-containing raw material and a manganese-containing raw material.

[0066] The nickel-containing raw material may be a nickel-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof. For example, the nickel-containing raw material may be Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4·6H2O, nickel fatty acid salts, nickel halides, or a combination thereof, but is not limited thereto.

[0067] The above manganese-containing raw material may be a manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof. For example, the above manganese-containing raw material may be a manganese oxide such as Mn2O3, MnO2, Mn3O4, etc.; a manganese salt such as MnCO3, Mn(NO3)2·4H2O, MnSO4·H2O, manganese acetate, manganese dicarboxylate, manganese citrate, manganese fatty acid, manganese fatty acid; manganese oxyhydroxide, manganese chloride, or a combination thereof, but is not limited thereto.

[0068] The above transition metal aqueous solution may further include one or more elements selected from alkali metals, alkaline earth metals, transition metals other than nickel and manganese, post-transition metals, and metalloids.

[0069] The above transition metal aqueous solution may optionally include a cobalt-containing raw material.

[0070] The above cobalt-containing raw material may be a cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof. For example, the above cobalt-containing raw material may be Co(OH)2, CoOOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O, CoSO4, Co(SO4)2ㆍ7H2O, Co(SO3)2, or a combination thereof, but is not limited thereto.

[0071] The above transition metal aqueous solution may optionally include a dopant-containing raw material.

[0072] The above dopant may be at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge, and Nd, at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Ca, Mg, W, Ce, V, Ta, and Y, or at least one selected from Al, P, B, Si, Ti, Zr, and W.

[0073] The above dopant-containing raw material may be included in the above transition metal aqueous solution in the form of sulfates, acetates, nitrates, halides, sulfides, hydroxides, oxides, and / or oxyhydroxides.

[0074] The content of manganese (mol%) in the above transition metal aqueous solution may be greater than the content of nickel (mol%). For example, the above transition metal aqueous solution may contain 50 mol% or more of manganese relative to the total moles of the transition metal.

[0075] As described below, in order for the positive active material prepared using the positive active material precursor defined herein to be formed as a solid solution in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group are solid, it is preferable that the manganese content (mol%) in the transition metal aqueous solution be 50 mol% or more and less than 80 mol% with respect to the total molar amount of the transition metal.

[0076] The ammonium cation complex-forming agent may be, for example, NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, NH4CO3, or a combination thereof, but is not limited thereto. The ammonium cation complex-forming agent may be used in the form of an aqueous solution. An aqueous solution containing the ammonium cation complex-forming agent may be prepared by adding the ammonium cation complex-forming agent to deionized water or a mixed solvent containing deionized water.

[0077] The above basic aqueous solution may be a hydroxide, oxide, or combination thereof of an alkali metal or alkaline earth metal such as NaOH, KOH, or Ca(OH)2. The above basic aqueous solution may be used in the form of an aqueous solution. The above basic aqueous solution may be prepared by adding a hydroxide, oxide, or combination thereof of an alkali metal or alkaline earth metal to deionized water or a mixed solvent containing deionized water.

[0078] The above basic aqueous solution can be used to adjust the pH when a transition metal aqueous solution, an ammonium cation complex forming agent, and a basic aqueous solution are introduced into the above reactor to carry out a co-precipitation reaction.

[0079] In the present invention, the co-precipitation reaction may be performed at a pH greater than 8.0 and less than 10.0, a pH greater than 8.1 and less than 9.9, a pH greater than 8.2 and less than 9.8, a pH greater than 8.3 and less than 9.7, a pH greater than 8.4 and less than 9.6, or a pH greater than 8.5 and less than 9.5.

[0080] Since pH can affect the co-precipitation rate of transition metals during the above co-precipitation reaction, it is desirable to maintain a constant pH while the reaction is being performed.

[0081] When the pH is 10.0 or higher during the above co-precipitation reaction, the specific surface area of ​​the cathode active material precursor may become excessively small as the primary particles constituting the cathode active material precursor are formed thickly (the short length of the primary particles increases). If the specific surface area of ​​the cathode active material precursor is excessively small, the surface kinetic properties of the cathode active material manufactured using the cathode active material precursor may be degraded.

[0082] When the pH is 8.0 or lower during the above co-precipitation reaction, the decrease in the co-precipitation rate of nickel leads to a large deviation between the nickel content in the cathode active material precursor and the design composition, resulting in a non-uniform particle size distribution and the formation of excessive fine particles. As the particle size distribution of the cathode active material precursor becomes non-uniform and the fine particle content increases, the span value and BET specific surface area calculated from the particle size distribution of the cathode active material precursor increase, and the capacity and rate characteristics of the cathode active material manufactured using the cathode active material precursor may be degraded, and in particular, side reactions with the electrolyte may be promoted.

[0083] In the present invention, the co-precipitation reaction may be carried out under a non-oxidizing atmosphere or an oxidizing atmosphere. For example, the co-precipitation reaction may be initiated after creating a non-oxidizing atmosphere by purging an inert gas, such as nitrogen (N2) or argon (Ar), into the reactor.

[0084] As another example, an inert gas such as nitrogen (N2) or argon (Ar) may be purged into the reactor to create a non-oxidizing atmosphere, and then a mixed gas containing oxygen (O2) may be supplied to create a predetermined oxidizing atmosphere, after which the co-precipitation reaction may be initiated. The mixed gas may be a mixture of oxygen (O2) and an inert gas (e.g., nitrogen (N2)).

[0085] When the above co-precipitation reaction is performed in an oxidizing atmosphere, the shape of the primary particles constituting the anode active material precursor can be controlled, and the BET specific surface area can be improved to an appropriate level. Specifically, when the above co-precipitation reaction is performed in an oxidizing atmosphere, the length of the major axis of the primary particles can be reduced, thereby improving the internal porosity of the anode active material precursor to an appropriate level.

[0086] In the present invention, the above co-precipitation reaction may be carried out under an oxidizing atmosphere containing oxygen (O2) in an amount of 0.5 volume% or more and less than 6.0 volume%, 0.5 volume% or more and less than 5.0 volume%, 0.5 volume% or more and less than 4.0 volume%, or 0.5 volume% or more and less than 3.0 volume%. An oxidizing atmosphere containing oxygen (O2) in an amount of 0.5 volume% or more and less than 6.0 volume% may be formed by supplying a mixed gas containing oxygen (O2) in an amount of 0.5 volume% or more and less than 6.0 volume% into the reactor. The remainder of the mixed gas, excluding oxygen, may be an inert gas (e.g., nitrogen (N2)).

[0087] When the oxygen (O2) in the mixed gas supplied into the reactor is 6.0 volume% or more, the primary particles constituting the positive active material precursor become thicker, and the proportion of impurities in the positive active material precursor may increase.

[0088] In this invention, the co-precipitation reaction may be carried out at a temperature of 50°C or higher and less than 80°C, 50°C or higher and less than 75°C, or 50°C or higher and less than 70°C.

[0089] If the temperature during the above co-precipitation reaction is below 50°C, not only is it not possible to sufficiently supply the energy required for the co-precipitation reaction, but the content of impurities in the cathode active material precursor may increase, overall particle growth may be insufficient, or the internal porosity may become excessively high. On the other hand, if the temperature during the above co-precipitation reaction is above 80°C, the primary particles constituting the cathode active material precursor may be formed excessively thick. As the primary particles constituting the cathode active material precursor become thicker, the internal porosity decreases, and through this, the specific surface area of ​​the precursor may decrease rapidly.

[0090] The above co-precipitation reaction time may vary depending on the particle size of the cathode active material precursor to be manufactured. For example, the above co-precipitation reaction may be performed for 5 to 120 hours, but is not limited thereto.

[0091] After the above co-precipitation reaction is completed, a washing and / or drying process may be performed on the cathode active material precursor. The washing and drying process may be performed by methods known in the art. For example, the cathode active material precursor may be washed with ultrapure water and dried using methods such as vacuum drying, natural drying, or spray drying.

[0092]

[0093] positive electrode active material precursor

[0094] According to another aspect of the present invention, a positive active material precursor comprising a transition metal hydroxide represented by the following chemical formula 1 is provided.

[0095] [Chemical Formula 1]

[0096] [Ni b Co c Mn d M1 e ](OH)2

[0097] In the above chemical formula 1,

[0098] M1 is at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge and Nd, and

[0099] 0≤b<0.5, 0≤c≤0.2, 0.5≤d<0.8, 0 <e≤0.1, b+c+d+e=1이다.

[0100] The transition metal hydroxide has a secondary particle form in which a plurality of primary particles are aggregated, and the surface shape of the primary particles exposed on the surface of the transition metal hydroxide, as observed from a surface SEM image of the transition metal hydroxide, may have a major axis and a minor axis. The surface of the secondary particle corresponds to a set of exposed surfaces of the primary particles located at the outermost edge of the secondary particle.

[0101] The shape of such primary particles can be inferred from the surface shape of the primary particles exposed on the surface of the secondary particles observed from the surface SEM image of the secondary particles and the cross-sectional shape of the primary particles observed from the cross-sectional SEM image of the secondary particles.

[0102] The average value of the ratio of the major axis length to the minor axis length (major axis length / minor axis length) of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide may be 1.5 or more and 25.0 or less, 2.0 or more and 24.0 or less, 3.0 or more and 23.0 or less, 4.0 or more and 23.0 or less, or 4.7 or more and 22.4 or less.

[0103] As a result of the above co-precipitation reaction, if the primary particles grow excessively thick or grow excessively small, the average value of the ratio of the major axis length to the minor axis length (major axis length / minor axis length) of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide may be less than 1.5. If the primary particles grow excessively thick, there is a concern that the electrochemical properties may deteriorate as the porosity within the surface of the lithium manganese-based oxide obtained by calcining the transition metal hydroxide decreases and the surface kinetics decrease. In addition, if the primary particles have an excessively small size, the specific surface area of ​​the lithium manganese-based oxide obtained by calcining the transition metal hydroxide increases rapidly, which may increase side reactions between the lithium manganese-based oxide and the electrolyte.

[0104] Meanwhile, if the average value of the ratio of the major axis length to the minor axis length (major axis length / minor axis length) of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is greater than 9.0, as the number of primary particles having an excessively thin shape increases, the porosity of the lithium manganese-based oxide obtained by calcining the transition metal hydroxide increases, thereby decreasing the energy density per unit volume, or the specific surface area increases, thereby increasing the side reactions between the lithium manganese-based oxide and the electrolyte.

[0105] The average value of the short segment length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide may be 30 nm or more and 270 nm or less, 50 nm or more and 270 nm or less, 70 nm or more and 270 nm or less, 80 nm or more and 270 nm or less, or 84 nm or more and 260 nm or less.

[0106] If the average value of the short axis length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is smaller than 30 nm, it may be difficult to reduce side reactions between the lithium manganese oxide and the electrolyte as the size of the primary particles exposed on the surface of the lithium manganese oxide obtained by calcining the transition metal hydroxide becomes excessively small or excessively thin.

[0107] On the other hand, if the average value of the short axis length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is greater than 270 nm, the surface kinetics, such as lithium ion conductivity, may be degraded as the size of the primary particles exposed on the surface of the lithium manganese oxide obtained by calcining the transition metal hydroxide becomes excessively large.

[0108] The average value of the major axis length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide may be 400 nm or more and 2500 nm or less, 400 nm or more and 2400 nm or less, 400 nm or more and 2300 nm or less, 500 nm or more and 2300 nm or less, 500 nm or more and 2200 nm or less, 500 nm or more and 2100 nm or less, 600 nm or more and 2000 nm or less, or 600 nm or more and 1900 nm or less.

[0109] If the average value of the major axis length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is smaller than 400 nm, it may be difficult to reduce side reactions between the lithium manganese oxide and the electrolyte as the size of the primary particles exposed on the surface of the lithium manganese oxide obtained by calcining the transition metal hydroxide becomes excessively small.

[0110] On the other hand, if the average value of the major axis length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is greater than 2500 nm, the surface kinetics, such as lithium ion conductivity, may be degraded as the size of the primary particles exposed on the surface of the lithium manganese oxide obtained by calcining the transition metal hydroxide becomes excessively large.

[0111] Average particle size (D of the above transition metal hydroxide) 50 ) is 5.0μm to 24.0μm, 6.0μm to 20.0μm, or 7.0μm to 15.0μm.

[0112] Meanwhile, the transition metal hydroxide defined herein may be used as a precursor for manufacturing a positive active material exhibiting a bimodal particle size distribution or an anode active material exhibiting a trimodal particle size distribution, or as a precursor for manufacturing a positive active material exhibiting a trimodal particle size distribution. The positive neutral refers to a particle having an average particle size between that of a small particle and an anode active material exhibiting a trimodal particle size distribution.

[0113] Average particle size (D) of the transition metal hydroxide for manufacturing an anode active material exhibiting a bimodal type particle size distribution or an anode active material exhibiting a trimodal type particle size distribution 50 ) may be 5.0μm to 24.0μm, 6.0μm to 20.0μm, 6.0μm to 18.0μm, 6.0μm to 16.0μm, or 6.0μm to 15.0μm.

[0114] Average particle size (D) of the transition metal hydroxide for manufacturing a neutral of an anode active material exhibiting a trimodal type particle size distribution 50) may be 5.0μm to 15.0μm, 5.0μm to 10.0μm, or 5.0μm to 8.0μm.

[0115] The span value for the particle size of the transition metal hydroxide calculated by the following Equation 1 may be 0.90 or less, or 0.88 or less.

[0116] [Equation 1]

[0117] span value = (D 90 -D 10 ) / D 50

[0118] If the span value for the particle size of the above transition metal hydroxide is greater than 0.90, the particle size distribution of the above positive active material precursor is non-uniform, and the above positive active material precursor may contain an excessive amount of fine particles.

[0119] The above-mentioned positive active material precursor has a BET specific surface area of ​​8.0 m² as measured by the nitrogen adsorption method. 2 / g to 28.0m 2 / g, 10.0m 2 / g to 28.0m 2 / g, 11.0m 2 / g to 28.0m 2 / g, 12.0m 2 / g to 27.0m 2 / g, or 13.2m 2 / g to 26.2m 2 It can be / g.

[0120] The BET specific surface area of ​​the above positive electrode active material precursor is 8.0 m² 2 If it is smaller than / g, the specific surface area of ​​the lithium manganese-based oxide prepared using the above-mentioned cathode active material precursor becomes excessively small, making it difficult to improve the capacity and rate characteristics of the cathode active material containing the lithium manganese-based oxide. On the other hand, if the BET specific surface area of ​​the above-mentioned cathode active material precursor is 28.0m² 2If it is greater than / g, the specific surface area of ​​the lithium manganese-based oxide prepared using the above-mentioned cathode active material precursor becomes excessively large, and consequently, as the possibility of side reactions between the lithium manganese-based oxide and the electrolyte increases, the stability of the cathode active material containing the lithium manganese-based oxide may be reduced.

[0121] When analyzing the X-ray diffraction spectrum of the above-mentioned positive active material precursor, the ratio (a / b) of the diffraction peak intensity (a) appearing in the 2θ=11.8±1° region to the diffraction peak intensity (b) appearing in the 2θ=18.6±1° region may be 0.25 or less, 0.20 or less, 0.15 or less, 0.11 or less, 0.105 or less, or 0.103 or less.

[0122] When analyzing the X-ray diffraction spectrum of the above-mentioned positive electrode active material precursor, the diffraction peak appearing in the 2θ=18.6±1° region is [Ni represented by the above-mentioned Chemical Formula 1 b Co c Mn d M1 e The peak corresponding to ](OH)2 is the peak, and the diffraction peak appearing in the region 2θ=11.8±1° is the peak corresponding to the MnO2 phase.

[0123] When analyzing the X-ray diffraction spectrum of the above-mentioned positive active material precursor, the ratio (a / b) of the diffraction peak intensity (a) appearing in the 2θ=11.8±1° region to the diffraction peak intensity (b) appearing in the 2θ=18.6±1° region is greater than 0.25, which means that the proportion of MnO2, an impurity phase, in the above-mentioned positive active material precursor is excessively high. In this case, the capacity and rate characteristics of the positive active material manufactured using the above-mentioned positive active material precursor may be degraded.

[0124]

[0125] Method for manufacturing positive electrode active material

[0126] According to another aspect of the present invention, a method for manufacturing a positive electrode active material using a positive electrode active material precursor defined herein is provided.

[0127] According to the present invention, the shape and physical properties of the precursor of the lithium manganese-based oxide can be controlled according to the synthesis (co-precipitation reaction) conditions, and thereby, the cathode active material manufactured using the precursor having appropriate specific surface area and internal density can have improved capacity and rate characteristics.

[0128] The method for manufacturing the above-described positive active material comprises the steps of: forming an oxide precursor by first heat treating a positive active material precursor defined herein (specifically, a transition metal hydroxide represented by the above-described chemical formula 1); and forming a lithium manganese-based oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group exist as a solid solution by mixing the oxide precursor and a lithium raw material and then performing a second heat treatment.

[0129] The transition metal hydroxide represented by the above chemical formula 1 can be converted into an oxide precursor by undergoing a first heat treatment in an air-atmosphere furnace at 300°C to 700°C, 400°C to 600°C, or 450°C to 550°C for 1 hour to 36 hours.

[0130] Subsequently, a mixture is prepared by mixing the oxide-state precursor and the lithium raw material, and then the mixture is subjected to a second heat treatment in a furnace in an O2 atmosphere at 700°C to 1000°C, 800°C to 950°C, or 850°C to 950°C for 2 to 36 hours to obtain a positive electrode active material comprising a lithium manganese-based oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group exist as a solid solution.

[0131] As the above lithium raw material, lithium-containing carbonates (e.g., Li2CO3, etc.), hydrates (e.g., lithium hydroxide hydrate (LiOH·H2O), etc.), hydroxides (e.g., LiOH, etc.), nitrates (e.g., lithium nitrate (LiNO3), etc.), chlorides (e.g., lithium chloride (LiCl), etc.), and combinations thereof may be used.

[0132] The above lithium raw material can be mixed such that the molar ratio of lithium to the total metal elements present in the oxide-state precursor (Li / Metal molar ratio) is greater than 1, 1.1 to 1.6, 1.1 to 1.5, 1.2 to 1.6, or 1.2 to 1.5.

[0133] Optionally, a dopant-containing raw material can be mixed to dope at least one of a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group before the second heat treatment.

[0134] The above dopant may be at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge, and Nd, at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Ca, Mg, W, Ce, V, Ta, and Y, or at least one selected from Al, P, B, Si, Ti, Zr, and W.

[0135] The above dopant-containing raw material may be mixed in the form of sulfates, acetates, nitrates, halides, sulfides, hydroxides, oxides, and / or oxyhydroxides.

[0136] Optionally, a halogen-containing raw material can be mixed to substitute some of the oxygen of the lithium manganese-based oxide before the second heat treatment.

[0137] The above halogen may be F, Cl, Br and / or I, and preferably F. For halogen doping of the lithium manganese-based oxide, at least one anion dopant selected from LiF, MgF2, HF, F2, XeF2, TbF4, CeF4, CoF3, AgF2, MoF3, AgF, CuF2, FeF3, CuF, VF3, CrF3, ZrF4, BaF2, CaF2, AlF3, NH4F, CeF3, and CsF may be used.

[0138]

[0139] positive electrode active material

[0140] According to another aspect of the present invention, a positive electrode active material comprising a lithium manganese-based oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group are dissolved is provided.

[0141] The above-mentioned positive electrode active material comprises a lithium manganese-based oxide prepared using a positive electrode active material precursor prepared by the method defined herein.

[0142] The phases belonging to the C2 / m space group and the R-3m space group can be distinguished not only by the composition constituting each phase but also by specific peaks for each phase during XRD analysis. For example, specific peaks for the phase belonging to the C2 / m space group may appear in the 2θ=20.8±1° region, and specific peaks for the phase belonging to the R-3m space group may appear in the 2θ=18.6±1° region.

[0143] The above lithium manganese-based oxide is a composite oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group are dissolved, and the phase belonging to the C2 / m space group and the phase belonging to the R-3m space group coexist within the lithium manganese-based oxide. Furthermore, the above lithium manganese-based oxide is different from a composite oxide having a spinel crystal structure belonging to the Fd-3m space group (e.g., LiMn2O4 or an oxide having a similar composition).

[0144] The above lithium manganese-based oxide may be a composite oxide of lithium, nickel, and manganese. Additionally, the above lithium manganese-based oxide may further include one or more elements selected from alkali metals, alkaline earth metals, transition metals other than nickel and manganese, post-transition metals, and metalloids.

[0145] The above lithium manganese oxide is also referred to as an overlithiated layered oxide (OLO) because the number of moles of lithium present in the lithium manganese oxide is greater than the sum of the number of moles of other transition metals (generally, when the molar ratio of lithium to all metal elements other than lithium in the lithium manganese oxide (Li / (Metal molar ratio)) is greater than 1).

[0146] In addition, the above lithium manganese-based oxide is also referred to as a layered oxide with excess lithium and manganese, as the manganese content present in the lithium manganese-based oxide is greater than the content of other transition metals.

[0147] Generally, considering that commercially available ternary lithium composite oxides of nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) compositions contain 20 mol% or less of the total metal elements excluding lithium, the lithium manganese-based oxide has a relatively high proportion of manganese among the total metal elements (e.g., 50 mol% or more, 52 mol% or more, 53 mol% or more, or 55 mol% or more) compared to commercially available ternary lithium composite oxides.

[0148] In addition, considering that commercially available ternary lithium composite oxides of nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) compositions contain 60 mol% or more of nickel among all metal elements excluding lithium (80 mol% or more in the case of high-Ni type), the lithium manganese-based oxide has a relatively low proportion of nickel among all metal elements (e.g., less than 50 mol%, 48 mol% or less, 46 mol% or less, 45 mol% or less, 44 mol% or less, 42 mol% or less, or 40 mol% or less) compared to commercially available ternary lithium composite oxides.

[0149] There is also a difference in that the Li / Metal molar ratio measured from the lithium manganese-based oxides defined herein is greater than that of ternary lithium composite oxides such as nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA). For example, the Li / Metal molar ratio of ternary lithium composite oxides such as nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) has a value close to 1. On the other hand, the Li / Metal molar ratio of the lithium manganese-based oxides defined herein is greater than 1, and preferably has a value of 1.1 to 1.6, 1.1 to 1.5, 1.2 to 1.6, or 1.2 to 1.5.

[0150] Accordingly, in this invention, lithium manganese-based oxides may be defined as complex oxides in which the content of manganese among all metal elements excluding lithium is 50 mol% or more, or as complex oxides in which the content of manganese among all metal elements excluding lithium is 50 mol% or more and the content of nickel is less than 50 mol%.

[0151] Additionally, in the present invention, a lithium manganese-based oxide may be defined as a composite oxide in which the molar ratio of lithium to all metal elements excluding lithium is greater than 1, or has a value of 1.1 to 1.6, 1.1 to 1.5, 1.2 to 1.6, or 1.2 to 1.5, and the content of manganese among all metal elements excluding lithium is 50 mol% or more, or as a composite oxide in which the molar ratio of lithium to all metal elements excluding lithium is greater than 1, or has a value of 1.1 to 1.6, 1.1 to 1.5, 1.2 to 1.6, or 1.2 to 1.5, and the content of manganese among all metal elements excluding lithium is 50 mol% or more, and the content of nickel is less than 50 mol%.

[0152] Despite the aforementioned differences in composition, the lithium manganese-based oxide can also function as a complex metal oxide capable of lithium ion intercalation / deintercalation.

[0153] The lithium manganese-based oxide included in the positive electrode active material defined herein may exist as an aggregate in which a plurality of primary particles are aggregated. When the lithium manganese-based oxide exists as an aggregate in which a plurality of primary particles are aggregated, the lithium manganese-based oxide may be referred to as a secondary particle.

[0154] The above primary particle refers to a particle unit in which no grain boundaries appear when observed using a scanning electron microscope at a magnification of 5,000 to 20,000 times.

[0155] The primary particles constituting the lithium manganese-based oxide defined herein may have an average particle size of 0.05 μm to 5 μm, 0.1 μm to 5.0 μm, 0.25 μm to 3.0 μm, or 0.25 μm to 2.0 μm. In this case, the average particle size of the primary particles may be the average value of the length in the major axis direction and the length in the minor axis direction of the primary particles ([major axis length + minor axis length] / 2). The average particle size of the primary particles may be calculated as the average value of the particle sizes of all primary particles observed from the surface SEM image and / or cross-sectional SEM image of the lithium manganese-based oxide.

[0156] When the average particle size of the primary particles is smaller than 0.05 μm, the specific surface area of ​​the lithium manganese-based oxide (secondary particles) composed of the primary particles is relatively large. In this case, the likelihood of side reactions between the lithium manganese-based oxide and the electrolyte occurring during storage or operation of the lithium secondary battery may increase.

[0157] On the other hand, if the average particle size of the primary particle is greater than 5 μm, the growth of the primary particle is excessively induced, and consequently, the diffusion path of lithium ions within the primary particle also becomes longer. If the diffusion path of lithium ions within the primary particle is excessively long, the mobility of lithium ions within the primary particle and the diffusivity of lithium ions mediated by the primary particle are reduced, which causes an increase in the resistance of the lithium manganese-based oxide (secondary particle) composed of the primary particle.

[0158] Accordingly, in order to reduce the specific surface area of ​​the lithium manganese-based oxide and simultaneously prevent the reduction of the mobility of lithium ions within the primary particles and the diffusion of lithium ions mediated by the primary particles, the average particle size of the primary particles may be 0.05 μm to 5 μm, 0.1 μm to 5.0 μm, 0.25 μm to 3.0 μm, or 0.25 μm to 2.0 μm.

[0159] The average particle size (D) of the above secondary particles 50 ) may be 5.0 μm to 24.0 μm. The average particle size (D) of the secondary particles is 50 ) may vary depending on the number of primary particles constituting the secondary particles. The average particle size of the secondary particles can be measured using the laser diffraction method. For example, after dispersing the secondary particles in a dispersion medium, they can be introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiated with ultrasound of approximately 28 kHz at an output of 60 W, obtained a volume cumulative particle size distribution graph, and then measured by determining the particle size corresponding to 50% of the volume cumulative amount.

[0160] For example, the lithium manganese-based oxide defined herein may be used as a positive electrode active material exhibiting a bimodal or trimodal particle size distribution to improve the insufficient energy density per unit volume. Accordingly, the lithium manganese-based oxide defined herein may be used as a sub-particle and / or allele of a positive electrode active material exhibiting a bimodal particle size distribution, or as a sub-particle, a neutral particle (a particle having an average particle size between that of a sub-particle and an allele), and / or an allele of a positive electrode active material exhibiting a trimodal particle size distribution.

[0161] When the lithium manganese-based oxide defined herein is used as an alternative to a positive electrode active material exhibiting a bimodal particle size distribution or a trimodal particle size distribution, the average particle size (D) of the secondary particles 50 ) may be 5.0μm to 24.0μm, 6.0μm to 20.0μm, 6.0μm to 18.0μm, 6.0μm to 16.0μm, or 6.0μm to 15.0μm.

[0162] When the lithium manganese-based oxide defined herein is used as a neutral component of a positive electrode active material exhibiting a trimodal type particle size distribution, the average particle size (D) of the secondary particles 50 ) may be 5.0μm to 15.0μm, 5.0μm to 10.0μm, or 5.0μm to 8.0μm.

[0163] In this document, "particle size" is used interchangeably with "particle diameter" or "particle size," and unless otherwise defined, all "average particle size" refers to the intermediate volume-based particle size determined by laser diffraction.

[0164] Unless otherwise defined, the term “surface of the primary particle” as used herein refers to the outer surface of the primary particle exposed to the outside. Likewise, the term “surface of the secondary particle” as used herein refers to the outer surface of the secondary particle exposed to the outside. As previously stated, the “surface of the secondary particle” formed by the aggregation of a plurality of primary particles corresponds to the exposed surface of the primary particle present on the surface portion of the secondary particle.

[0165] Additionally, unless otherwise defined, the term "surface of the particle" as used herein refers to an area relatively close to the "foremost surface" of the particle, and the term "center of the particle" refers to an area relatively closer to the "center" of the particle than the "surface." Accordingly, the "surface of the primary particle" refers to an area relatively close to the "foremost surface" of the primary particle, and the term "center of the primary particle" refers to an area relatively closer to the "center" of the primary particle than the "surface." Likewise, the "surface of the secondary particle" refers to an area relatively close to the "foremost surface" of the secondary particle, and the term "center of the secondary particle" refers to an area relatively closer to the "center" of the secondary particle than the "surface."

[0166] In this case, the region within any particle excluding the "surface" can be defined as the "center of the particle."

[0167] In the present invention, when r is the half-diameter of the lithium manganese oxide measured from the cross-sectional SEM image of the lithium manganese oxide, the distance (d) from the center of the lithium manganese oxide is (1 / 2)r <d인 영역을 표면부(surface portion), 상기 리튬 망간계 산화물의 중심으로부터의 거리(d)가 0≤d≤(1 / 2)r인 영역을 중심부(center portion)으로 정의할 수 있다. 여기서, 상기 리튬 망간계 산화물은 2차 입자인 것을 전제로 한다.

[0168] Since the secondary particle may not have a perfect sphere, the half-diameter (r) of the secondary particle can be calculated from the average value of the major axis length and minor axis length of the lithium manganese-based oxide measured from the cross-sectional SEM image of the secondary particle. That is, the half-diameter (r) of the secondary particle can be considered as half the value of the average value of the major axis length and minor axis length of the lithium manganese-based oxide measured from the cross-sectional SEM image of the secondary particle.

[0169] The lithium manganese-based oxide defined herein may be represented by the following chemical formula 2 or chemical formula 3.

[0170] [Chemical Formula 2]

[0171] Li(Li a Ni b Co c Mn d M1 e )O 2-f X f

[0172] In the above chemical formula 2,

[0173] M1 is at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge and Nd, and

[0174] X is a halogen capable of substituting some of the oxygen present in the above lithium manganese-based oxide, and

[0175] 0 <a≤0.7, 0≤b<0.5, 0≤c≤0.2, 0.5≤d<0.8, 0<e≤0.1, 0≤f≤0.1이다.

[0176] [Chemical Formula 3]

[0177] rLi2MnO 3-p X p ·(1-r)Li u Ni w Co x Mn y M2 z O 2-p' X' p'

[0178] In the above chemical formula 3,

[0179] M2 is at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge, and Nd, and

[0180] X and X' are halogens capable of substituting some of the oxygen present in the lithium manganese-based oxide, and

[0181] 0.2 <r≤0.7, 0<u≤1, 0≤w≤1, 0≤x≤0.2, 0.3<y<1, 0<z≤0.1, 0≤p≤0.1, 0≤p'≤0.1이다.

[0182] In the above chemical formulas 2 and 3, X and X' are each halogen elements capable of independently substituting a portion of the oxygen present in the lithium manganese-based oxide. Refer to the periodic table for the types of halogens that can be used as X and X', such as F, Cl, Br and / or I, and preferably F.

[0183] In the above chemical formulas 2 and 3, M1 and M2 may each be independently at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge, and Nd, at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Ca, Mg, W, Ce, V, Ta, and Y, and at least one selected from Al, P, B, Si, Ti, Zr, and W.

[0184] The Li / Metal molar ratio measured from the lithium manganese-based oxide represented by Chemical Formula 2 or Chemical Formula 3 may be greater than 1, 1.1 to 1.6, 1.1 to 1.5, 1.2 to 1.6, or 1.2 to 1.5. It is possible to form a lithium manganese-based oxide with an excess of lithium if the Li / Metal molar ratio measured from the lithium manganese-based oxide has a value greater than at least 1. In addition, in order for the lithium manganese-based oxide to appropriately form a solid solution in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group are dissolved, and at the same time to exhibit high capacity under a high-voltage operating environment, it is preferable that the Li / Metal molar ratio of the lithium manganese-based oxide be 1.1 to 1.5, 1.2 to 1.6, or 1.2 to 1.5.

[0185] In addition, in order to properly form a solid solution in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group are dissolved, it is preferable that the content of manganese among the total metal elements, excluding lithium present in the lithium manganese-based oxide represented by the above chemical formula 2 or the above chemical formula 3, be 50 mol% or more.

[0186] In order for the above lithium manganese-based oxide to have the characteristics of an OLO that exhibits high capacity under a high voltage operating environment, the content of manganese among the total metal elements excluding lithium present in the above lithium manganese-based oxide may be 50 mol% or more and less than 80 mol%, 51 mol% or more and less than 80 mol%, 52 mol% or more and less than 80 mol%, 53 mol% or more and less than 80 mol%, 54 mol% or more and less than 80 mol%, 55 mol% or more and less than 80 mol%, 50 mol% or more and less than 75 mol%, 51 mol% or more and less than 75 mol%, 52 mol% or more and less than 75 mol%, 53 mol% or more and less than 75 mol%, 54 mol% or more and less than 75 mol%, and 55 mol% to 75 mol%. If the manganese content in the above lithium manganese-based oxide exceeds 80 mol%, a phase transition may occur due to the movement of transition metals (particularly manganese) within the lithium manganese-based oxide during formation and / or operation of the lithium secondary battery. This phase transition forms a spinel phase, and the spinel phase, acting as an impurity in the lithium manganese-based oxide, may cause a decrease in charge / discharge capacity or voltage decay during the cycling of the lithium secondary battery. Additionally, if the manganese content in the above lithium manganese-based oxide exceeds 80 mol%, it may be difficult to sufficiently form a phase belonging to the R-3m space group.

[0187] In order to properly form a solid solution in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group are dissolved, the content of nickel among the total metal elements excluding lithium present in the lithium manganese-based oxide represented by the above formula 2 or the above formula 3 may be 0% or more and less than 50 mol%, 5 mol% or more and less than 48 mol%, 10 mol% or more and less than 46 mol%, 15 mol% or more and less than 45 mol%, 20 mol% or more and less than 44 mol mol%, 20 mol% or more and less than 42 mol%, or 20 mol% or more and less than 40 mol%.

[0188] If the nickel content in the above lithium manganese-based oxide is 50 mol% or more, it may be difficult to sufficiently form the C2 / m phase, or the phase belonging to the C2 / m space group and the phase belonging to the R-3m space group may not form a sufficient solid solution, which may cause phase separation during formation and / or operation of the lithium secondary battery.

[0189] The lithium manganese oxide represented by Chemical Formula 2 or Chemical Formula 3 may optionally contain cobalt. If the lithium manganese oxide contains cobalt, the mole fraction of cobalt relative to the total number of moles of metal elements in the lithium manganese oxide may be 20% or less, 15% or less, or 10% or less. In other cases, the lithium manganese oxide represented by Chemical Formula 2 or Chemical Formula 3 may have a cobalt-free composition that does not contain cobalt.

[0190] In general, commercially available ternary lithium composite oxides of nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) compositions have a single phase in which a phase belonging to the R-3m space group exists.

[0191] On the other hand, the lithium-excess lithium manganese-based oxide represented by the above Chemical Formula 2 or the above Chemical Formula 3 is an oxide of a phase belonging to the C2 / m space group represented by Li2MnO3 (hereinafter referred to as the 'C2 / m phase') and Li u Ni w Co x Mn y M2 z It exists as a complex oxide in which an oxide of a phase belonging to the R-3m space group denoted by O2 (hereinafter referred to as the 'R-3m phase') is dissolved. For example, the lithium manganese-based oxide may exist in a state in which an oxide of the C2 / m phase and an oxide of the R-3m phase form a solid solution.

[0192] In this case, a complex oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group are simply physically and / or chemically bonded or attached does not correspond to a solid solution as defined herein.

[0193] For example, a composite oxide having a phase in the C2 / m space group, formed by mixing a metal oxide having a phase in the C2 / m space group and a metal oxide having a phase in the R-3m space group and coating the surface with a metal oxide having a phase in the R-3m space group, does not correspond to a solid solution as defined herein.

[0194] In the lithium manganese-based oxide represented by Chemical Formula 3 above, if r exceeds 0.7, the proportion of Li2MnO3, which is an oxide of the phase belonging to the C2 / m space group among the lithium manganese-based oxides, becomes excessively high. Consequently, there is a concern that the discharge capacity may decrease as the irreversible capacity and resistance of the cathode active material increase. That is, in order to sufficiently activate the oxide of the phase belonging to the C2 / m space group, which has relatively high resistance among the lithium manganese-based oxides, and to improve surface kinetics, it is desirable that the oxide of the phase belonging to the R-3m space group be present in a proportion greater than a predetermined amount. The ratio of the phase belonging to the C2 / m space group and the phase belonging to the R-3m space group among the lithium manganese-based oxides can be calculated through the compositional ratio of lithium and transition metal present in the lithium manganese-based oxides.

[0195]

[0196] lithium secondary battery

[0197] According to another aspect of the present invention, an anode may be provided comprising an anode current collector and an anode active material layer formed on the anode current collector. Herein, the anode active material layer may comprise a lithium manganese-based oxide according to various embodiments of the present invention described above as an anode active material.

[0198] Therefore, a detailed description of the lithium manganese-based oxide is omitted, and only the remaining unmentioned components will be described below. Additionally, for convenience, the aforementioned lithium manganese-based oxide will be referred to as the positive electrode active material below.

[0199] The above positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the above positive current collector may typically have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the current collector to increase the adhesion of the positive active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0200] The above positive active material layer can be manufactured by applying a positive slurry composition, which includes a conductive material and optionally a binder together with the positive active material, to the positive current collector.

[0201] At this time, the positive active material may be included in an amount of 80 wt% to 99 wt%, more specifically 85 wt% to 98.5 wt%, based on the total weight of the positive active material layer. Excellent capacity characteristics may be exhibited when included within the above-mentioned content range, but it is not necessarily limited thereto.

[0202] The above conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. The above conductive material may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0203] The above binder serves to improve adhesion between positive active material particles and adhesion between the positive active material and the 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, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), 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 binder may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive active material layer.

[0204] The above-described anode can be manufactured according to a conventional anode manufacturing method, except for using the above-described anode active material. Specifically, it can be manufactured by applying an anode slurry composition, prepared by dissolving or dispersing the above-described anode active material and optionally a binder and a conductive material in a solvent, onto an anode current collector, and then drying and rolling.

[0205] The above solvent may be a solvent commonly used in the relevant technical field, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it has a viscosity that dissolves or disperses the anode active material, conductive material, and binder, taking into account the coating thickness of the slurry and the manufacturing yield, and subsequently provides excellent thickness uniformity when coated for anode manufacturing.

[0206] In addition, in another embodiment, the anode may be manufactured by casting the anode slurry composition onto a separate support and then laminating the film obtained by peeling off from the support onto an anode current collector.

[0207] In addition, according to another aspect of the present invention, an electrochemical device comprising the anode described above may be provided. Specifically, the electrochemical device may be a battery, a capacitor, etc., and more specifically, a lithium secondary battery.

[0208] Specifically, the above lithium secondary battery may include a positive electrode, a negative electrode positioned opposite to the positive electrode, and a separator and an electrolyte interposed between the positive electrode and the negative electrode. Here, since the positive electrode is the same as previously described, a detailed description is omitted for convenience, and only the remaining components not previously mentioned are described in detail below.

[0209] The above lithium secondary battery may optionally further include a battery container that accommodates the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0210] The above cathode may include a cathode current collector and a cathode active material layer located on the cathode current collector.

[0211] 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. 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 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.

[0212] The above-mentioned cathode active material layer can be manufactured by applying a cathode slurry composition, which includes a conductive material and optionally a binder together with the above-mentioned cathode active material, to the above-mentioned cathode current collector.

[0213] As the above-mentioned negative electrode active material, a compound capable of reversible intercalation / deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous 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; metal oxides capable of doping and dedoping lithium, such as SiOα (0 < α < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the above-mentioned metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the above-mentioned negative electrode active material. Furthermore, the carbon material may include both low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial 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.

[0214] The above negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0215] The above binder is a component that assists in the bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0216] The above conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10 wt% or less, preferably 5 wt% or less, based on the total weight of the negative electrode active material layer. Such 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 acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fiber or metal fiber; metal powder such as carbon fluoride, aluminum, or nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0217] In one embodiment, the negative active material layer may be manufactured by applying a negative slurry composition, prepared by dissolving or dispersing a negative active material and optionally a binder and a conductive material in a solvent, onto a negative current collector and drying it, or by casting the negative slurry composition onto a separate support and then laminating the film obtained by peeling it off from the support onto a negative current collector.

[0218] In addition, in another embodiment, the negative active material layer may be manufactured by applying a negative slurry composition prepared by dissolving or dispersing a negative active material and optionally a binder and a conductive material in a solvent onto a negative current collector and drying it, or by casting the negative slurry composition onto a separate support and then laminating the film obtained by peeling it off from the support onto a negative current collector.

[0219] Meanwhile, in the above-mentioned lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. Any separator typically used in lithium secondary batteries can be used without special limitations, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte moisture retention capacity. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may be used. Furthermore, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0220] In addition, the electrolytes used in this invention include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used in the manufacture of lithium secondary batteries, but are not limited to these.

[0221] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0222] 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); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. 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.In this case, using a mixture of cyclic carbonate and chain carbonate in a volume ratio of about 1:1 to about 1:9 can result in excellent performance of the electrolyte.

[0223] The above lithium salt can be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the above lithium salt is LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2) 2. LiCl, LiI, or LiB(C2O4)2, etc., may be used. It is preferable to use the lithium salt within a concentration range of 0.1M to 2.0M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and lithium ions can move effectively.

[0224] When the electrolyte used in the present invention is a solid electrolyte, for example, solid inorganic electrolytes such as sulfide-based solid electrolytes, oxide-based solid electrolytes, nitride-based solid electrolytes, halide-based solid electrolytes, etc. may be used, and preferably, sulfide-based solid electrolytes may be used.

[0225] As a material for a sulfide-based solid electrolyte, a solid electrolyte containing Li, an element X (wherein X is at least one selected from P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In) and S may be used. Examples of the above-mentioned sulfide-based solid electrolyte materials include Li2S-P2S5, Li2S-P2S-LiX (wherein X is a halogen element such as I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z m S n (Here, m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (Here, p and q are integers, and M is P, Si, Ge, B, Al, Ga, or In) etc.

[0226] The solid electrolyte, preferably a sulfide-based solid electrolyte, may be amorphous or crystalline, or may be in a mixed state of amorphous and crystalline.

[0227] Li7La3Zr2O is a material for oxide-based solid electrolytes. 12 , Li 7-x La3Zr 1-x Nb x O 12 , Li 7-3x La3Zr2Al x O 12 , Li 3x La 2 / 3-x TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, Li 3+x PO4-x N x (LiPON), Li 2+2x Zn 1-x There are GeO4 (LISICON), etc.

[0228] The aforementioned solid electrolyte may be disposed as a separate layer (solid electrolyte layer) between the anode and the cathode. Additionally, the solid electrolyte may be partially included within the anode active material layer of the anode independently of the solid electrolyte layer, or the solid electrolyte may be partially included within the cathode active material layer of the cathode independently of the solid electrolyte layer.

[0229] In addition to the above electrolyte components, the above electrolyte may further include one or more additives 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, such as, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, 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. In this case, the additive may be included in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

[0230] As described above, since the lithium secondary battery containing the positive electrode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and lifespan characteristics, it is useful in portable devices such as mobile phones, laptop computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0231] The external shape of the lithium secondary battery according to the present invention is not subject to any particular limitations, but may be cylindrical, prismatic, pouch, or coin-shaped using a can. In addition, the lithium secondary battery can be used not only as a battery cell used as a power source for small devices, but can also preferably be used as a unit cell in a medium-to-large battery module containing a plurality of battery cells.

[0232] According to another aspect of the present invention, a battery module comprising the lithium secondary battery as a unit cell and / or a battery pack comprising the same may be provided.

[0233] The battery module or the battery pack may be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0234]

[0235] The present invention will be described in more detail below through examples. However, these examples are intended solely to illustrate the present invention and should not be interpreted as limiting the scope of the present invention.

[0236]

[0237] Preparation Example 1. Preparation of a positive electrode active material precursor

[0238] Comparative Example 1

[0239] A 2.5 M aqueous transition metal solution, 6.3 M NaOH (aq), and 7.2 M NH4OH (aq) were mixed in a molar ratio of 40:60 with NiSO4·6H2O and MnSO4·H2O, and stirred at 400 rpm while introducing them into a 90 L reactor in which a non-oxidizing atmosphere was created by purging with nitrogen (N2) gas. The transition metal solution was introduced into the reactor at a rate of 1.1 L / hr, the NaOH (aq) at a rate of 0.61 L / hr, and the NH4OH (aq) at a rate of 0.18 L / hr.

[0240] The temperature inside the reactor was maintained at 50℃ and the pH at 10.0, and a co-precipitation reaction was carried out for 24 hours while supplying nitrogen (N2) gas into the reactor at a rate of 1 L / min.

[0241] After the co-precipitation reaction was completed, the precursor was separated, washed with deionized water, and dried at 120°C for 10 hours to obtain the cathode active material precursor.

[0242]

[0243] Example 1

[0244] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as Comparative Example 1, except that the pH in the reactor was maintained at 9.5. The transition metal aqueous solution was introduced into the reactor at 1.1 L / hr, the NaOH (aq) was introduced at 0.57 L / hr, and the NH4OH (aq) was introduced at 0.18 L / hr.

[0245]

[0246] Example 2

[0247] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as Comparative Example 1, except that the pH in the reactor was maintained at 9.3. The transition metal aqueous solution was introduced into the reactor at a rate of 1.1 L / hr, the NaOH (aq) was introduced at a rate of 0.55 L / hr, and the NH4OH (aq) was introduced at a rate of 0.18 L / hr.

[0248]

[0249] Example 3

[0250] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as Comparative Example 1, except that the pH in the reactor was maintained at 9.0. The transition metal aqueous solution was introduced into the reactor at 1.1 L / hr, the NaOH (aq) was introduced at 0.52 L / hr, and the NH4OH (aq) was introduced at 0.18 L / hr.

[0251]

[0252] Example 4

[0253] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as Comparative Example 1, except that the pH in the reactor was maintained at 8.5. The transition metal aqueous solution was introduced into the reactor at 1.1 L / hr, the NaOH (aq) was introduced at 0.48 L / hr, and the NH4OH (aq) was introduced at 0.18 L / hr.

[0254]

[0255] Comparative Example 2

[0256] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as Comparative Example 1, except that the pH in the reactor was maintained at 8.0. The transition metal aqueous solution was introduced into the reactor at 1.1 L / hr, the NaOH (aq) was introduced at 0.42 L / hr, and the NH4OH (aq) was introduced at 0.18 L / hr.

[0257]

[0258] Example 5

[0259] A 2.5 M aqueous transition metal solution, 6.3 M NaOH (aq), and 7.2 M NH4OH (aq) were mixed in a molar ratio of 40:60 with NiSO4·6H2O and MnSO4·H2O and stirred at 400 rpm while introducing them into a 90 L reactor in which a non-oxidizing atmosphere was created by purging with nitrogen (N2) gas. The aqueous transition metal solution was introduced into the reactor at a rate of 1.1 L / hr, the NaOH (aq) at a rate of 0.52 L / hr, and the NH4OH (aq) at a rate of 0.18 L / hr.

[0260] The temperature inside the reactor was maintained at 50℃ and the pH at 9.0, and a co-precipitation reaction was carried out for 24 hours while supplying a mixed gas containing nitrogen (N2) and oxygen (O2) (containing 0.5 volume% of O2) into the reactor at a rate of 0.5 L / min.

[0261] After the co-precipitation reaction was completed, the precursor was separated, washed with deionized water, and dried at 120°C for 10 hours to obtain the cathode active material precursor.

[0262]

[0263] Example 6

[0264] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 5, except that a mixed gas containing nitrogen (N2) and oxygen (O2) (containing 1.0 volume% of O2) was supplied into the reactor at a rate of 0.5 L / min.

[0265]

[0266] Example 7

[0267] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 5, except that a mixed gas containing nitrogen (N2) and oxygen (O2) (containing 2.0 volume% O2) was supplied into the reactor at a rate of 0.5 L / min.

[0268]

[0269] Example 8

[0270] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 5, except that a mixed gas containing nitrogen (N2) and oxygen (O2) (containing 3.0 volume% O2) was supplied into the reactor at a rate of 0.5 L / min.

[0271]

[0272] Comparative Example 3

[0273] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 5, except that a mixed gas containing nitrogen (N2) and oxygen (O2) (containing 6.0 volume% O2) was supplied into the reactor at a rate of 0.5 L / min.

[0274]

[0275] Example 9

[0276] A 2.5 M aqueous transition metal solution, 6.3 M NaOH (aq), and 7.2 M NH4OH (aq) were mixed in a molar ratio of 40:60 with NiSO4·6H2O and MnSO4·H2O, and stirred at 400 rpm while introducing them into a 90 L reactor in which a non-oxidizing atmosphere was created by purging with nitrogen (N2) gas. The transition metal solution was introduced into the reactor at a rate of 1.1 L / hr, the NaOH (aq) at a rate of 0.52 L / hr, and the NH4OH (aq) at a rate of 0.18 L / hr.

[0277] The temperature inside the reactor was maintained at 60°C and the pH at 9.0, and a co-precipitation reaction was carried out for 24 hours while supplying a mixed gas containing nitrogen (N2) and oxygen (O2) (containing 1.0 volume% of O2) into the reactor at a rate of 0.5 L / min.

[0278] After the co-precipitation reaction was completed, the precursor was separated, washed with deionized water, and dried at 120°C for 10 hours to obtain the cathode active material precursor.

[0279]

[0280] Example 10

[0281] A positive electrode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 9, except that the temperature of the reactor was maintained at 70℃.

[0282]

[0283] Comparative Example 4

[0284] A positive electrode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 9, except that the temperature of the reactor was maintained at 80℃.

[0285]

[0286] Comparative Example 5

[0287] A positive electrode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 9, except that the temperature of the reactor was maintained at 45℃.

[0288]

[0289] Example 11

[0290] A cathode active material precursor was prepared by performing a co-precipitation reaction in the same manner as in Example 9, except that the temperature of the reactor was maintained at 70°C and a mixed gas containing nitrogen (N2) and oxygen (O2) (containing 2.0 volume% of O2) was supplied into the reactor at a rate of 0.5 L / min.

[0291]

[0292] Preparation Example 2. Preparation of positive electrode active material

[0293] A positive electrode active material was prepared using each positive electrode active material precursor prepared according to Preparation Example 1.

[0294] Specifically, each hydroxide precursor obtained in Preparation Example 1 was heat-treated at 550°C for 5 hours in a furnace under an air atmosphere, and then furnace-cooled to be converted into an oxide precursor.

[0295] Next, a mixture was prepared by mixing the above oxide-state precursor with LiOH (Li / (Li-excluding metal) molar ratio = 1.22), which is a lithium raw material.

[0296] Subsequently, the above mixture was heat-treated at 900°C for 8 hours in a furnace under an O2 atmosphere and then furnace-cooled to obtain a positive electrode active material comprising a lithium manganese-based oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group exist as a solid solution.

[0297]

[0298] Preparation Example 3. Preparation of a lithium secondary battery (half-cell)

[0299] A positive electrode slurry was prepared by dispersing 90 wt% of each positive electrode active material prepared according to Preparation Example 2, 4.5 wt% of carbon black, and 5.5 wt% of PVDF binder in N-methyl-2-pyrrolidone (NMP). The positive electrode slurry was uniformly coated onto an aluminum thin film with a thickness of 15 μm and vacuum dried at 135°C to produce a positive electrode for a lithium secondary battery. A half-cell was prepared using a lithium foil as a counter electrode for the positive electrode, a porous polyethylene film (Celgard 2300, thickness: 25 μm) as a separator, and an electrolyte containing LiPF6 at a concentration of 1.15 M in a solvent mixed with ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a volume ratio of 2:4:4.

[0300]

[0301] Experimental Example 1. Analysis of Physical Properties and Shape of Anode Active Material Precursor

[0302] The physical properties and morphology of each cathode active material precursor prepared according to Preparation Example 1 were analyzed, and the results of the analysis are shown in Table 1 below.

[0303]

[0304] (1) Analysis of particle size of the positive electrode active material precursor

[0305] The particle size distribution of each positive active material precursor prepared according to Preparation Example 1 was analyzed using a known laser diffraction method. Specifically, after dispersing each positive active material precursor in a dispersion medium, a laser diffraction particle size measuring device (Microtrac MT 3000) was used to irradiate ultrasound of approximately 28 kHz with an output of 60 W, and then a volumetric cumulative particle size distribution graph was obtained.

[0306] Next, from the above volume cumulative particle size distribution graph, the particle size (D) corresponding to 10% of the volume cumulative amount 10 ), particle size corresponding to 50% of the volume accumulation (D 50 ) and particle size corresponding to 50% of the volume accumulation (D 90 ) was measured. The span value was calculated using Equation 1 below.

[0307] [Equation 1]

[0308] span value = (D 90 -D 10 ) / D 50

[0309]

[0310] (2) Analysis of particle shape of positive electrode active material precursor

[0311] Each cathode active material precursor prepared in Preparation Example 1 was photographed using a scanning electron microscope to obtain a surface SEM image of the precursor in the form of a secondary particle. Using an image analysis program (Image-Pro image analysis software for SEM), 30% of the primary particles (20 particles) exposed on the surface of the secondary particles observed from the surface SEM image were randomly selected. For the selected primary particles, the major axis length and the minor axis length of the surface shape of the primary particles were measured, and their average values ​​were calculated. In addition, the major axis / minor axis ratio, which is the ratio of the average major axis length of the primary particles to the average minor axis length of the primary particles, was calculated.

[0312]

[0313] (3) Analysis of the BET specific surface area of ​​the cathode active material precursor

[0314] The BET specific surface area for each cathode active material precursor prepared in Preparation Example 1 was calculated using the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77K) using BELSORP-mini II from BEL Japan.

[0315]

[0316] (4) Analysis of the composition of the positive electrode active material precursor

[0317] The composition (content of Ni and Mn) of each cathode active material precursor prepared according to Preparation Example 1 was analyzed using a known ICP-OES (Inductively Coupled Plasma-Emission Spectroscopy) method.

[0318]

[0319] (5) XRD analysis of the cathode active material precursor

[0320] X-ray diffraction (XRD) analysis was performed on each cathode active material precursor prepared in Preparation Example 1, and the ratio (a / b) of the diffraction peak intensity (a) appearing in the 2θ=11.8±1° region to the diffraction peak intensity (b) appearing in the 2θ=18.6±1° region was calculated. The XRD analysis was performed using a Bruker D8 Advance diffractometer with Cu-Kα radiation (1.540598Å).

[0321] Classification D 50 (μm)span value Axis length (nm) Major length (nm) Major / Axis ratio Surface area (m² 2 / g)Ni(mol%)Mn(mol%) a / b Comparative Example 1 12.6 0.6 64621093.36.739.46 0.6 0.042 Example 1 140.5 626018987.313.239.86 0.20.055 Example 2 12.10.5 5163185011.318.139.36 0.7 0.069 Example 3 12.40.5 984188522.42 0.939.96 0.10.092 Example 4 9.30.6 78518722223.54 0.95 9.10.102 Comparative Example 27.40.9380178022.335.237.562.51.403 Example 57.10.7585140016.518.939.960.10.088 Example 67.50.8087127114.620.439.960.10.088 Example 78.10.8893101510.924.139.860.20.103 Example 89.10.811106005.526.240600.101 Comparative Example 312.80.6914112588.926.140.559.50.271 Example 99.40.6912311839.618.340.359.70.065 Example 1010.80.6515311267.416.840.659.40.062 Comparative Example 412.10.6327112014.412.540.859.20.064 Comparative Example 54.91.0283150118.121.739.760.30.094 Example 1110.30.621788314.719.740.359.70.066

[0322]

[0323] Referring to the results of Examples 1 to 4 and Comparative Example 1 and Comparative Example 2, it can be seen that when the pH is excessively high during the co-precipitation reaction (Comparative Example 1), the primary particles are formed thickly (the short length of the primary particles increases), resulting in an excessively small specific surface area of ​​the cathode active material precursor. On the other hand, when the pH is excessively low (Comparative Example 2), there is a large deviation between the nickel content in the precursor and the design composition, and the particle size distribution is non-uniform. Through the high span value of Comparative Example 2, it can be inferred that fine particles were excessively formed due to the excessively low pH. Additionally, it can be seen that the specific surface area of ​​Comparative Example 2 became excessively large.

[0324] Referring to the results of Examples 5 to 8 and Comparative Example 3, it can be observed that the major axis length of the primary particles shortens as a gas mixed with O2 is supplied during the co-precipitation reaction. As the major axis length of the primary particles shortens, the internal porosity of the precursor increases, thereby allowing the specific surface area to be improved to an appropriate level. However, if the content of O2 in the gas supplied during the co-precipitation reaction becomes excessively high (Comparative Example 3), the primary particles become thicker again, and it can be observed that the intensity of the diffraction peak appearing in the 2θ=11.8±1° region increases. The diffraction peak appearing in the 2θ=11.8±1° region corresponds to the MnO2 phase, and as the intensity of the diffraction peak appearing in the 2θ=11.8±1° region increases, the proportion of the impurity phase within the precursor increases.

[0325] Comparing the results of Example 6 with Examples 9 to 11, it can be confirmed that fine particle formation is suppressed at relatively high reaction temperatures and a precursor with a uniform particle size distribution can be obtained, as the span value decreases as the reaction temperature increases during the co-precipitation reaction. Additionally, it can be confirmed that the formation of impurity phases can be suppressed as the reaction temperature increases during the co-precipitation reaction. On the other hand, comparing the results of Examples 9 to 11 with Comparative Example 4, it can be confirmed that when the reaction temperature during the co-precipitation reaction becomes excessively high (e.g., 80°C or higher), the primary particles are formed excessively thickly. As the primary particles become thicker, the internal porosity decreases, which can lead to a rapid decrease in the specific surface area of ​​the precursor. Meanwhile, referring to the results of Comparative Example 5, it can be confirmed that overall particle growth is insufficient due to the low reaction temperature during the co-precipitation reaction.

[0326]

[0327] Experimental Example 3. Evaluation of Electrochemical Characteristics of a Lithium Secondary Battery (Half-Cell)

[0328] For the lithium secondary battery (half-cell) prepared in Preparation Example 3, the initial charge capacity, initial discharge capacity, initial efficiency, and the 2.0C / 0.1C discharge capacity ratio (rate capability (C-rate)) were measured through charge / discharge experiments using an electrochemical analyzer (Toyo, Toscat-3100) at 25℃, a voltage range of 2.0V to 4.6V, and a discharge rate of 0.1C to 5.0C.

[0329] The above measurement results are shown in Table 2 below.

[0330] Classification Charge Capacity (mAh / g) Discharge Capacity (mAh / g) Initial Efficiency (%) 2.0C / 1.0C Discharge Capacity Ratio (%) Comparative Example 1 190.5 161.4 84.7 42.80 Example 1 217.4 190.4 87.6 58.10 Example 2 219.4 193.1 88.00 63.30 Example 3 232.3 204.7 88.10 68.80 Example 4 230.2 204.7 88.90 67.20 Comparative Example 2 201.2 174.8 86.90 49.10 Example 5 248.4 221.1 89.00 72.70 Example 6 251.1 223.3 88.90 73.30 Example 7259.2231.189.2077.80 Example 8257.6229.889.2077.60 Comparative Example 3210.4184.087.5054.50 Example 9245.8217.188.3068.00 Example 10241.1212.388.0065.30 Comparative Example 4197.1167.885.1050.80 Comparative Example 5204.0179.888.2058.00 Example 11249.1220.288.4075.20

[0331]

[0332] When comparing the results of Examples 1 to 4 with Comparative Examples 1 and 2, it can be seen that when the pH is excessively high (Comparative Example 1) or excessively low (Comparative Example 2) during the co-precipitation reaction, the charge / discharge capacity and the 2.0C / 0.1C discharge capacity ratio are low. In other words, it can be seen that using a precursor obtained through a co-precipitation reaction under a pH greater than 8.0 and less than 10.0, preferably under a pH of 8.5 to 9.5, contributes to the improvement of the charge / discharge capacity and rate characteristics of the cathode active material.

[0333] Comparing the results of Examples 1 to 4 with Examples 5 to 8, it can be confirmed that when a gas mixed with O2 is supplied during the co-precipitation reaction, the charge / discharge capacity and rate characteristics of the positive electrode active material can be further improved. On the other hand, comparing the results of Examples 5 to 8 with Comparative Example 3, it can be confirmed that if the proportion of O2 in the mixed gas supplied during the co-precipitation reaction becomes excessively high, it may actually induce excessive changes in the physical properties and shape of the precursor, thereby degrading the charge / discharge capacity and rate characteristics of the positive electrode active material.

[0334] Comparing the results of Example 6 with Examples 9 to 11, it can be confirmed that even if the reaction temperature during the co-precipitation reaction increases, the decrease in the charge / discharge capacity and rate characteristics of the cathode active material is minimal. On the other hand, comparing the results of Examples 9 to 11 with Comparative Examples 4 and 5, it can be confirmed that if the reaction temperature during the co-precipitation reaction is higher or lower than the appropriate level, excessive changes in the physical properties and shape of the precursor are induced, which may degrade the charge / discharge capacity and rate characteristics of the cathode active material.

[0335]

[0336] Although embodiments of the present invention have been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the present invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention.

Claims

1. A step comprising introducing an aqueous transition metal solution, an ammonium cation complex forming agent, and an aqueous basic solution into a reactor and co-precipitating under conditions of pH greater than 8.0 and pH less than 10.0 to form a transition metal hydroxide precursor, The manganese content (mol%) in the above transition metal aqueous solution is greater than the nickel content (mol%), Method for manufacturing a positive electrode active material precursor.

2. In Paragraph 1, The above transition metal aqueous solution further comprises one or more elements selected from alkali metals, alkaline earth metals, transition metals other than nickel and manganese, post-transition metals, and metalloids. Method for manufacturing a positive electrode active material precursor.

3. In Paragraph 1, The above transition metal aqueous solution contains 50 mol% or more of manganese relative to the total moles of the transition metal, Method for manufacturing a positive electrode active material precursor.

4. In Paragraph 1, The above co-precipitation reaction is performed at a pH of 8.5 to 9.5, Method for manufacturing a positive electrode active material precursor.

5. In Paragraph 1, The above co-precipitation reaction is carried out under a non-oxidizing or oxidizing atmosphere, Method for manufacturing a positive electrode active material precursor.

6. In Paragraph 1, The above co-precipitation reaction is carried out under an oxidizing atmosphere containing 0.5 volume% or more and less than 6.0 volume% of oxygen, Method for manufacturing a positive electrode active material precursor.

7. In Paragraph 1, The above co-precipitation reaction is performed at a temperature of 50°C or higher and less than 80°C, Method for manufacturing a positive electrode active material precursor.

8. Includes a transition metal hydroxide represented by the following chemical formula 1, and The above transition metal hydroxide has a secondary particle form in which a plurality of primary particles are aggregated, and The surface morphology of the primary particles exposed on the surface of the transition metal hydroxide, as observed from the surface SEM image of the transition metal hydroxide, has a major axis and a minor axis, Positive active material precursor: [Chemical Formula 1] [Ni b Co c Mr d M1 e ](OH)2 In the above chemical formula 1, M1 is at least one selected from Al, P, Nb, B, Si, Ti, Zr, Ba, K, Mo, Fe, Cu, Cr, Zn, Na, Ca, Mg, Pt, Au, Eu, Sm, W, Ce, V, Ta, Sn, Hf, Gd, Y, Ru, Ge and Nd, and 0≤b<0.5, 0≤c≤0.2, 0.5≤d<0.8, 0 <e≤0.1, b+c+d+e=1이다.

9. In Paragraph 8, The average value of the ratio of the major axis length to the minor axis length (major axis length / minor axis length) of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is 1.5 or greater and 25.0 or less, Positive active material precursor.

10. In Paragraph 8, The average value of the short axis length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is 30 nm or more and 270 nm or less, Positive active material precursor.

11. In Paragraph 8, The average value of the major axis length of the surface shape of the primary particles exposed on the surface of the transition metal hydroxide is 400 nm or more and 2500 nm or less, Positive active material precursor.

12. In Paragraph 8, Average particle size (D of the above transition metal hydroxide) 50 ) is 5.0μm to 24.0μm, and The span value for the particle size of the transition metal hydroxide calculated by the following Equation 1 is 0.90 or less, Positive active material precursor: [Equation 1] span value = (D 90 -D 10 ) / D 50 13. In Paragraph 8, The BET specific surface area measured by the nitrogen adsorption method is 8.0 m² 2 / g to 28.0m 2 / g person, Positive active material precursor.

14. In Paragraph 8, When analyzing the X-ray diffraction spectrum of the above-mentioned positive active material precursor, the ratio (a / b) of the diffraction peak intensity (a) appearing in the 2θ=11.8±1° region to the diffraction peak intensity (b) appearing in the 2θ=18.6±1° region is 0.25 or less, Positive active material precursor.

15. A step of forming an oxide precursor by performing a first heat treatment on an anode active material precursor according to any one of claims 8 to 14; and A step of mixing the oxide precursor and the lithium raw material and then performing a second heat treatment to form a lithium manganese-based oxide in which a phase belonging to the C2 / m space group and a phase belonging to the R-3m space group exist as a solid solution; including, Method for manufacturing a positive electrode active material.