Cathode active material and method for manufacturing same

Abstract

A method for manufacturing a cathode active material according to the present invention comprises the steps of: preparing a cathode active material precursor; setting the temperature in heat treatment equipment to a target firing temperature; and firing the cathode active material precursor, a lithium salt, and a dopant material at the target firing temperature using the heat treatment equipment to manufacture the cathode active material, wherein the target firing temperature is controlled according to the dopant material. The step for setting the temperature in the heat treatment equipment to a target firing temperature may include: a step for obtaining the difference value between a set firing temperature of the heat treatment equipment and the actual firing temperature in the heat treatment equipment; a step for constructing a DB on the basis of the difference value; and a step for using the DB to set the set firing temperature of the heat treatment equipment so that the target firing temperature matches the actual firing temperature in the heat treatment equipment.

Description

Cathode active material and method for producing the same

[0001] The present invention relates to a cathode active material and a method for producing the same, and more particularly, to a cathode active material comprising lithium metal, nickel metal, manganese metal, and a dopant, and a method for producing the same.

[0002] A cathode active material refers to an active material that exists in the cathode material of a secondary battery and electrochemically produces electrical energy.

[0003] The positive electrode active material present in the positive electrode initially contains lithium ions and provides lithium ions to the negative electrode during the charging process of the secondary battery.

[0004] Accordingly, cathode active materials are being used in various industries, such as lithium metal batteries, lithium air batteries, and lithium ion polymer batteries.

[0005] As the field of application increases, various cathode active materials are being studied. For example, Korean Patent Registration No. 10-0815583 discloses a method for producing a cathode active material for a lithium secondary battery, the method comprising the steps of: mixing a first metal including nickel, cobalt, and manganese, and an aqueous metal salt solution optionally containing a second metal, a chelating agent, and an aqueous basic solution to produce a coprecipitated compound; drying or heat-treating the coprecipitated compound to produce an active material precursor; and mixing the active material precursor and a lithium salt and calcining the mixture to produce a lithium composite metal oxide, wherein the lithium composite metal oxide is characterized in that it has a layered structure.

[0006] The technical problem to be solved by the present invention is to provide a method for manufacturing a cathode active material with improved reproducibility.

[0007] Another technical problem to be solved by the present invention is to provide a method for manufacturing a cathode active material in which the initial capacity and capacity retention rate for charge / discharge cycles of a lithium secondary battery are optimized.

[0008] Another technical problem that the present invention seeks to solve is to provide a method for manufacturing a cathode active material with reduced manufacturing process costs.

[0009] Another technical problem that the present invention seeks to solve is to provide a method for manufacturing a cathode active material with a shortened manufacturing time.

[0010] Another technical problem that the present invention seeks to solve is to provide a method for manufacturing a cathode active material that is easy to mass-produce.

[0011] The technical problems to be solved by the present invention are not limited to those described above.

[0012] To solve the above technical problem, the present invention provides a method for manufacturing a cathode active material.

[0013] According to one embodiment, the method for manufacturing the cathode active material includes the steps of preparing a cathode active material precursor, setting a temperature within a heat treatment device to be a target firing temperature, and firing the cathode active material precursor, a lithium salt, and a dopant material at the target firing temperature using the heat treatment device to manufacture the cathode active material, wherein the target firing temperature is controlled depending on the dopant material, and the step of setting the temperature within the heat treatment device to be the target firing temperature may include the steps of obtaining a difference value between a set firing temperature of the heat treatment device and an actual firing temperature within the heat treatment device, constructing a DB based on the difference value, and using the DB, setting the set firing temperature of the heat treatment device so that the target firing temperature and the actual firing temperature within the heat treatment device match.

[0014] According to one embodiment, the step of setting the target firing temperature of the heat treatment equipment may include setting the set firing temperature of the heat treatment equipment lower than the target firing temperature of the heat treatment equipment.

[0015] According to one embodiment, the initial capacity and capacity retention rate of the lithium secondary battery may be controlled according to the target firing temperature.

[0016] According to one embodiment, the dopant material may include at least one of Nb, Ti, Zr, Hf, Ta, W, or Mo.

[0017] According to one embodiment, the target firing temperature may include being controlled to be 700°C or more and 900°C or less.

[0018] According to one embodiment, the dopant material may be Ti, and the target firing temperature may be controlled to be greater than 725°C and less than 750°C, or the dopant material may be Hf, and the target firing temperature may be controlled to be greater than 725°C and less than 775°C, or the dopant material may be Nb, and the target firing temperature may be controlled to be greater than 725°C and less than 775°C, or the dopant material may be Ta, and the target firing temperature may be controlled to be greater than 750°C and less than 800°C, or the dopant material may be W, and the target firing temperature may be controlled to be greater than 800°C and less than 900°C, or the dopant material may be Mo, and the target firing temperature may be controlled to be greater than 725°C and less than 750°C, or the dopant material may be Zr, and the target firing temperature may be controlled to be greater than 700°C and less than 750°C.

[0019] According to one embodiment, during the heat treatment process at the target sintering temperature, stress may be applied to the (104) plane of the preliminary positive electrode active material in which the positive electrode active material precursor, the lithium salt, and the dopant material are mixed, so that the particles of the positive electrode active material may grow from the (104) plane to the (003) plane.

[0020] According to one embodiment, the preliminary cathode active material may not contain cobalt.

[0021] In one embodiment, the peak value I corresponding to the (003) surface (003) And the peak value I corresponding to the above (104) surface (104) I is the ratio (003) / I (104 ) may include being controlled to be greater than 1.0 and less than 1.1.

[0022] According to one embodiment, the step of preparing the positive electrode active material precursor may include a step of preparing a transition metal hydroxide by a co-precipitation method using a transition metal precursor.

[0023] In one embodiment, the transition metal precursor does not include cobalt, and the transition metal precursor may include a nickel precursor and a manganese precursor.

[0024] According to one embodiment, the ratio of the positive electrode active material precursor, the lithium salt, and the dopant material may be controlled to be 1.03:1.00:0.01.

[0025] In one embodiment, the nickel precursor is NiSO 4ㆍ 6H2O, and the manganese precursor is MnSO 4ㆍ Contains 5H2O, and the lithium salt is LiOH ㆍ May contain H2O.

[0026] In order to solve the above technical problem, the present invention provides a cathode active material manufactured by the above-described method for manufacturing the cathode active material.

[0027] According to one embodiment, the cathode active material includes secondary particles in which a plurality of primary particles are aggregated, and among the surface and the inside of the cathode active material, the surface includes more primary particles having a rod shape than the inside, the cathode active material includes lithium metal, nickel metal in a ratio smaller than the lithium metal, manganese metal in a ratio smaller than the nickel metal, and a dopant in a ratio smaller than the manganese metal, and the dopant ratio is higher at the surface than at the inside, and the grain size of the cathode active material is 40 nm or more and 60 nm or less, and when the cathode active material is analyzed by XRD, a peak value I corresponding to the (003) plane is (003) Peak value I corresponding to (104) surface (104) I is the ratio (003) / I (104) It may include those greater than 1.0 and less than 1.1.

[0028] According to one embodiment, the positive electrode active material may not contain cobalt.

[0029] According to one embodiment, when the positive electrode active material is analyzed by XRD, the ratio of the c-axis and the a-axis of the crystal lattice of the positive electrode active material, c / 3a, may exceed 1.6459.

[0030] According to one embodiment, the cathode active material may include a transition metal layer including the nickel metal and the manganese metal and a lithium layer including the lithium metal, which are alternately and repeatedly laminated, and may include a superlattice in which +2 ions of the nickel metal are mixed within the lithium layer.

[0031] According to one embodiment, the dopant comprises Ti, and the ratio of +2 ions of the nickel metal mixed in the lithium layer is a temperature constant (θ) of the positive electrode active material. p) increases, including the temperature constant (θ) of the positive electrode active material. p ) may include more than 24.2K and less than 28.1K.

[0032] A method for manufacturing a cathode active material according to the present invention may include a step of preparing a cathode active material precursor, a step of setting a temperature within a heat treatment device to a target firing temperature, and a step of manufacturing the cathode active material by firing the cathode active material precursor, a lithium salt, and a dopant material at the target firing temperature using the heat treatment device.

[0033] In the step of setting the temperature within the heat treatment equipment to be the target sintering temperature, the set temperature displayed on the display disposed in the heat treatment equipment may be set lower than the target sintering temperature. Accordingly, the preliminary positive electrode active material, in which the positive electrode active material precursor, the lithium salt, and the dopant material are physically mixed, may be sintered at the target sintering temperature. Accordingly, during the sintering process of the preliminary positive electrode active material, changes in the characteristics of the positive electrode active material due to deviations in the sintering temperature may be minimized. In other words, the reproducibility of the production of the positive electrode active material may be improved. Accordingly, the positive electrode active material of the same quality may be provided.

[0034] And, in the step of manufacturing the positive electrode active material by firing the preliminary positive electrode active material at the target firing temperature using the heat treatment equipment, the target firing temperature can be controlled to be 700°C or more and 900°C or less. Specifically, the target firing temperature can be controlled differently depending on the dopant material in the preliminary positive electrode active material. When the dopant material is Ti, the target firing temperature of the preliminary positive electrode active material can be controlled to be more than 725°C and 750°C. Accordingly, the positive electrode active material with optimized initial capacity and capacity retention rate of a lithium secondary battery can be provided.

[0035] The cathode active material manufactured by the above-described method for manufacturing the cathode active material may include secondary particles formed by agglomeration of a plurality of primary particles. The plurality of primary particles may have a rod shape. The plurality of primary particles having a rod shape may be present more on the surface of the cathode active material than on the interior of the cathode active material.

[0036] And, the positive electrode active material may include lithium metal, nickel metal in a smaller proportion than the lithium metal, manganese metal in a smaller proportion than the nickel metal, and a dopant in a smaller proportion than the manganese metal. The dopant may be present at a higher proportion on the surface of the positive electrode active material than in the interior of the positive electrode active material.

[0037] In addition, the cathode active material may include a transition metal layer including the nickel metal and the manganese metal, which are alternately and repeatedly laminated, and a lithium layer including the lithium metal. The +2 ions of the nickel metal are mixed within the lithium layer, and the dopant is doped within the transition metal layer, so that the cathode active material may include a superlattice.

[0038] Accordingly, when the positive electrode active material is applied to the lithium secondary battery, the initial capacity and capacity retention rate for charge / discharge cycles of the lithium secondary battery can be optimized.

[0039] Figure 1 is a flowchart illustrating a method for manufacturing a cathode active material according to an embodiment of the present invention.

[0040] FIG. 2 is a drawing for explaining a nickel precursor, a manganese precursor, a lithium salt, and a dopant material according to an embodiment of the present invention.

[0041] FIG. 3 is a drawing for explaining a method for manufacturing a transition metal precursor by mixing a nigel precursor and a manganese precursor according to an embodiment of the present invention.

[0042] FIG. 4 is a drawing for explaining a method for manufacturing a cathode active material precursor by co-precipitation reaction of a transition metal precursor according to an embodiment of the present invention.

[0043] FIG. 5 is a drawing for explaining a method for manufacturing a preliminary positive electrode active material by mixing a positive electrode active material precursor, a lithium salt, and a dopant according to an embodiment of the present invention.

[0044] FIG. 6 is a drawing for explaining a method for manufacturing a cathode active material by firing a preliminary cathode active material according to an embodiment of the present invention.

[0045] FIG. 7 is a drawing for explaining the structure of a positive electrode active material according to an embodiment of the present invention.

[0046] Figure 8 is a graph for comparing the set firing temperature of the heat treatment equipment and the actual temperature within the heat treatment equipment according to an experimental example of the present invention.

[0047] Figures 9 to 11 are graphs for comparing the initial capacity and capacity retention rate for charge / discharge cycles of lithium ion batteries to which positive electrode materials according to experimental examples of the present invention are applied.

[0048] Figure 12 is a table for comparing the results of XRD analysis of positive electrode active materials according to experimental examples of the present invention.

[0049] Figures 13 and 14 are graphs for comparing the correlation between the performance of a lithium-ion battery to which a cathode active material is applied and the grain size of the cathode active material according to experimental examples of the present invention.

[0050] Figure 15 is a graph for comparing WH plots of positive electrode active materials according to comparative examples of the present invention.

[0051] Figures 16 to 22 are graphs for comparing WH plots of positive electrode active materials according to experimental examples of the present invention.

[0052] Figure 23 is an SEM photograph of a positive electrode active material according to Comparative Example 1-1 of the present invention.

[0053] Figures 24 to 30 are graphs for comparing SEM photographs and EDS Mapping analysis results of positive electrode active materials according to experimental examples of the present invention.

[0054] Figures 31 and 32 are graphs for comparing the crystal stability of positive electrode active materials according to comparative examples and experimental examples.

[0055] Figure 33 is a FIB-TEM photograph of a cathode active material according to Experiment 2-2 of the present invention.

[0056] Figure 34 is a FIB-TEM photograph of a cathode active material according to Experimental Example 2-5 of the present invention.

[0057] Figures 35 to 38 are graphs for comparing the crystal structure of the positive electrode active material according to Experimental Examples 2-2 and 2-5 before and after the charge / discharge cycle of the lithium ion battery to which the positive electrode active material according to Experimental Examples 2-2 and 2-5 of the present invention is applied.

[0058] Figure 39 is an SEM photograph of a positive electrode material according to Experimental Examples 2-2 and 2-5 of the present invention after performing a charge / discharge cycle on a lithium ion battery to which the positive electrode material according to Experimental Examples 2-2 and 2-5 of the present invention was applied.

[0059] Figure 40 shows the temperature constant (θ) for the positive electrode active material according to Experimental Examples 2-1, 2-2, and 2-5 of the present invention. p ) and I (003) / I (104) This is a graph for comparison.

[0060] Figure 41 is a table for comparing the ICP analysis results of positive electrode active materials according to experimental examples of the present invention.

[0061] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to sufficiently convey the spirit of the present invention to those skilled in the art.

[0062] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. In addition, in the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents.

[0063] Also, although terms such as first, second, and third have been used to describe various components in various embodiments of this specification, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiments. Also, the term "and / or" has been used herein to mean including at least one of the components listed before and after.

[0064] In the specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In addition, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, and should not be construed as excluding the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. In addition, the term "connection" is used in the present specification to mean both indirectly connecting multiple components and directly connecting them.

[0065] In addition, when describing the present invention below, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0066]

[0067] FIG. 1 is a flowchart for explaining a method for manufacturing a cathode active material according to an embodiment of the present invention, FIG. 2 is a diagram for explaining a nickel precursor, a manganese precursor, a lithium salt, and a dopant material according to an embodiment of the present invention, FIG. 3 is a diagram for explaining a method for manufacturing a transition metal precursor by mixing a nickel precursor and a manganese precursor according to an embodiment of the present invention, FIG. 4 is a diagram for explaining a method for manufacturing a cathode active material precursor by co-precipitation reaction of a transition metal precursor according to an embodiment of the present invention, FIG. 5 is a diagram for explaining a method for manufacturing a preliminary cathode active material by mixing a cathode active material precursor, a lithium salt, and a dopant according to an embodiment of the present invention, FIG. 6 is a diagram for explaining a method for manufacturing a cathode active material by calcining a preliminary cathode active material according to an embodiment of the present invention, and FIG. 7 is a diagram for explaining a structure of a cathode active material according to an embodiment of the present invention.

[0068] Referring to FIG. 1 and FIGS. 2 to 4, a positive electrode active material precursor (130) is prepared (S100).

[0069] The step of preparing the above-mentioned positive electrode active material precursor (130) may include a step of preparing a transition metal hydroxide by co-precipitating a transition metal precursor (132).

[0070] The above transition metal precursor (132) does not contain cobalt (Co), and may contain a nickel precursor (110) and a manganese precursor (120), as shown in FIG. 2. For example, the nickel precursor (100) may be NiSO 4ㆍ It may be 6H2O. For example, the manganese precursor (120) may be MnSO 4ㆍ It may be 5H2O. For example, the transition metal hydroxide may be NiMn(OH)2.

[0071] According to one embodiment, as illustrated in FIG. 3, the transition metal precursor (132) may be manufactured by mixing the nickel precursor (110) and the manganese precursor (120) at a lower ratio than the nickel precursor (100). For a specific example, the ratio of the nickel precursor (110) and the nickel precursor (100) may be 95:5.

[0072] And, as illustrated in FIG. 4, the positive electrode active material precursor (130) can be manufactured by a method of coprecipitating the transition metal precursor (132). For a specific example, the coprecipitation reaction can be performed in a nitrogen atmosphere. For a specific example, the coprecipitation reaction temperature can be 45.5°C. For a specific example, the pH condition of the coprecipitation reaction can be pH 11. For a specific example, the coprecipitation stirring speed can be 900 rpm. For a specific example, the coprecipitation reaction time can be 24 hours. For example, the positive electrode active material precursor (130) can be the transition metal hydroxide. For a specific example, the positive electrode active material precursor (130) can be nickel manganese hydroxide (Ni 0.95 Mn 0.05 (OH)2). Accordingly, the manufacturing process of the positive electrode active material precursor (130) is simplified, and the manufacturing time of the positive electrode active material (300) described later can be shortened. As a result, the manufacturing process cost of the positive electrode active material (300) described later is reduced, and mass production of the positive electrode active material (300) described later can be facilitated.

[0073] Referring to Fig. 1, the temperature inside the heat treatment equipment is set to be the target firing temperature (S200).

[0074] The step of setting the temperature within the heat treatment equipment to be the target firing temperature may include the step of obtaining a difference value between the set firing temperature of the heat treatment equipment and the actual firing temperature within the heat treatment equipment, the step of constructing a DB based on the difference value, and the step of using the DB to set the set firing temperature of the heat treatment equipment so that the target firing temperature and the actual firing temperature within the heat treatment equipment match.

[0075] In the present application, the set firing temperature of the heat treatment equipment means a temperature displayed on a display screen placed on the heat treatment equipment, and a temperature that a user of the heat treatment equipment can operate through the display screen.

[0076] In addition, the target firing temperature refers to the temperature at which the preliminary cathode active material (200) described below is fired. The target firing temperature can be controlled to be 700°C or higher and 900°C or lower. Specifically, the target firing temperature can be controlled differently depending on the dopant material (150) in the preliminary cathode active material (200) described below.

[0077] In addition, the actual firing temperature within the heat treatment equipment refers to the temperature measured in the reactor within the heat treatment equipment according to the set firing temperature of the heat treatment equipment. Accordingly, the difference value between the set firing temperature of the heat treatment equipment and the actual firing temperature within the heat treatment equipment refers to the difference between the set firing temperature of the heat treatment equipment and the actual temperature measured in the reactor within the heat treatment equipment.

[0078] As described later in FIG. 8, the actual temperature measured in the reactor within the heat treatment equipment may be higher than the set firing temperature of the heat treatment equipment. Accordingly, in the step of setting the target firing temperature of the heat treatment equipment, the set firing temperature of the heat treatment equipment may be set lower than the target firing temperature of the heat treatment equipment. Accordingly, the preliminary cathode active material (200) described later can be fired at the target firing temperature. Due to this, during the firing process of the preliminary cathode active material (200), a change in the characteristics of the cathode active material (300) described later due to a deviation in the firing temperature can be minimized. In other words, the reproducibility of the manufacturing of the cathode active material (300) described later can be improved. Accordingly, the cathode active material (300) described later of the same quality can be provided.

[0079] Referring to FIG. 1, FIG. 5, and FIG. 6, the cathode active material precursor (130), the lithium salt (140), and the dopant material (150) are fired at the target firing temperature using the heat treatment equipment to manufacture the cathode active material (300) (S300).

[0080] The above-described positive electrode active material precursor (130), the lithium salt (140), and the dopant material (150) can be physically mixed and manufactured into the above-described preliminary positive electrode active material (200), as shown in FIG. 5. For a specific example, the positive electrode active material precursor (130) can be nickel manganese hydroxide (Ni 0.95 Mn 0.05(OH)2). For example, the lithium salt (140) may be LiOHㆍH2O. For example, the dopant material (150) may be at least one of Nb, Ti, Zr, Hf, Ta, W, or Mo. For example, the mixing ratio of the positive electrode active material (130), the lithium salt (140), and the dopant material (150) may be 1.03:1.00:0.01.

[0081] And, the preliminary cathode active material (200) illustrated in FIG. 6 is provided to the reactor within the heat treatment equipment, and the preliminary cathode active material (200) is fired at the target firing temperature while supplying oxygen to the reactor, thereby producing the cathode active material (300). For example, the flow rate of oxygen supplied to the reactor can be controlled to 0.6 L / min.

[0082] Additionally, before firing the preliminary cathode active material (200) at the target firing temperature, the preliminary cathode active material (200) may be pre-heat treated at a temperature lower than the target firing temperature. At this time, for example, the heat treatment temperature of the preliminary cathode active material (200) may be 500°C.

[0083] As described above, the target firing temperature can be controlled to be 700°C or higher and 900°C or lower. Specifically, the target firing temperature can be controlled differently depending on the dopant material (150) in the preliminary cathode active material (200).

[0084] For example, when the dopant material (150) is Ti, the target firing temperature can be controlled to be greater than 725°C and less than 750°C. Accordingly, when the manufactured positive electrode active material (300) is applied to a lithium secondary battery, the initial capacity and capacity retention rate of the lithium secondary battery can be optimized. In contrast, when the manufactured positive electrode active material (300) by firing the preliminary positive electrode active material (200) at 725°C or less or 750°C or more is applied to the lithium secondary battery, the initial capacity and / or capacity retention rate of the lithium secondary battery may be reduced.

[0085] Therefore, in the method for manufacturing the positive electrode active material (300) according to the embodiment of the present application, when the dopant material (150) is Ti, the target sintering temperature of the preliminary positive electrode active material (200) can be controlled to be greater than 725°C and less than 750°C. Accordingly, the positive electrode active material (300) with optimized initial capacity and capacity retention rate of the lithium secondary battery can be provided.

[0086] In conclusion, the method for manufacturing the positive electrode active material (300) according to an embodiment of the present application may include a step of preparing the positive electrode active material precursor (130), a step of setting the temperature within the heat treatment equipment to be the target firing temperature, and a step of manufacturing the positive electrode active material (300) by firing the positive electrode active material precursor (130), the lithium salt (140), and the dopant material (150) at the target firing temperature using the heat treatment equipment.

[0087] In the step of setting the temperature within the heat treatment equipment to be the target sintering temperature, the set temperature displayed on the display disposed in the heat treatment equipment may be set lower than the target sintering temperature. Accordingly, the preliminary positive electrode active material (200), in which the positive electrode active material precursor (130), the lithium salt (140), and the dopant material (150) are physically mixed, may be sintered at the target sintering temperature. Accordingly, during the sintering process of the preliminary positive electrode active material (200), a change in the characteristics of the positive electrode active material (300) due to a deviation in the sintering temperature may be minimized. In other words, the reproducibility of the manufacturing of the positive electrode active material (300) may be improved. Accordingly, the positive electrode active material (300) of the same quality may be provided.

[0088] And, in the step of manufacturing the positive electrode active material (300) by firing the preliminary positive electrode active material (200) at the target firing temperature using the heat treatment equipment, the target firing temperature can be controlled to be 700°C or more and 900°C or less. Specifically, the target firing temperature can be controlled differently depending on the dopant material (150) in the preliminary positive electrode active material (200). When the dopant material is Ti, the target firing temperature of the preliminary positive electrode active material (200) can be controlled to be more than 725°C and 750°C. Accordingly, the positive electrode active material (300) having optimized initial capacity and capacity retention rate of the lithium secondary battery can be provided.

[0089] Referring to Fig. 7, the structure of the positive electrode active material (300) is described.

[0090] The above-described positive electrode active material (300) may include secondary particles formed by agglomeration of a plurality of primary particles (310), as illustrated in FIG. 7. The plurality of primary particles (310) may have a rod shape. The plurality of primary particles (310) having a rod shape may exist more on the surface of the positive electrode active material (300) than on the interior of the positive electrode active material (300).

[0091] And, the positive electrode active material (300) may include lithium metal, nickel metal in a smaller proportion than the lithium metal, manganese metal in a smaller proportion than the nickel metal, and a dopant in a smaller proportion than the manganese metal. The dopant may be present at a higher proportion on the surface of the positive electrode active material (300) than in the interior of the positive electrode active material (300). For example, the dopant may be at least one of Nb, Ti, Zr, Hf, Ta, W, or Mo. As a specific example, the dopant may be Ti. In addition, the positive electrode active material (300) may include a transition metal layer including the nickel metal and the manganese metal, which are alternately and repeatedly laminated, and a lithium layer including the lithium metal. Since +2 ions of the nickel metal are mixed in the lithium layer and the dopant is doped in the transition metal layer, the positive electrode active material (300) may include a superlattice.

[0092] Accordingly, when the positive electrode active material (300) is applied to the lithium secondary battery, the initial capacity and capacity retention rate for charge / discharge cycles of the lithium secondary battery can be optimized.

[0093] And, when analyzing the positive electrode active material (300) using XRD, as described later with reference to (b) of FIG. 31, c / 3a, which is the ratio of the c-axis and the a-axis of the crystal lattice of the positive electrode active material, may exceed 1.6459. Accordingly, the crystal stability of the positive electrode active material (300) may be improved. As a result, the durability of the positive electrode active material (300) may be increased, and the capacity retention rate for the charge / discharge cycle of the lithium secondary battery to which the positive electrode active material (300) is applied may be improved. In addition, when analyzing the positive electrode active material (300) using XRD, as described later with reference to FIG. 13, the grain size of the positive electrode active material (300) may be 40 nm to 60 nm. Accordingly, the initial capacity and the capacity retention rate for the charge / discharge cycle of the lithium secondary battery to which the positive electrode active material (300) is applied may be optimized. And, when analyzing the above-mentioned positive electrode active material (300) by XRD, as described later with reference to FIG. 14, the peak value (I) corresponding to the (003) plane (003) ) and the peak value corresponding to (104) surface (I (104) ) ratio (I (003) / I (104)) may be greater than 1.0 and less than 1.1. Accordingly, the ratio of the +2 ion of the nickel metal mixed in the lithium layer of the positive electrode active material (300) is optimized, so that the initial capacity and the capacity retention rate for the charge / discharge cycle of the lithium secondary battery to which the positive electrode active material (300) is applied can be optimized. In addition, as described below with reference to FIG. 17, the slope of the WH Plot (Williamson-Hall Plot) of the positive electrode active material (300) may exceed 0.00253. In addition, as described below with reference to FIG. 38, the positive electrode active material (300) may have a characteristic in which the slope of the WH Plot of the positive electrode active material (300) decreases after performing a charge / discharge cycle of the lithium secondary battery to which the positive electrode active material (300) is applied. And, as described later with reference to FIG. 40, the temperature constant (θ) of the positive electrode active material (300) p ) may be greater than 24.2 K and less than 28.1 K. Accordingly, the ratio of +2 ions of the nickel metal mixed in the lithium layer of the positive electrode active material (300) is optimized, so that the initial capacity and capacity retention rate for charge / discharge cycles of the lithium secondary battery to which the positive electrode active material (300) is applied can be optimized.

[0094] In conclusion, the cathode active material (300) according to the embodiment of the present application may include the secondary particles in which a plurality of the primary particles (310) are aggregated. The plurality of the primary particles (310) may have a rod shape. The plurality of the primary particles (310) having a rod shape may be present more on the surface of the cathode active material (300) than on the interior of the cathode active material (300).

[0095] In addition, the positive electrode active material (300) may include the lithium metal, the nickel metal in a smaller proportion than the lithium metal, the manganese metal in a smaller proportion than the nickel metal, and the dopant in a smaller proportion than the manganese metal. The dopant may be present at a higher proportion on the surface of the positive electrode active material (300) than in the interior of the positive electrode active material (300).

[0096] In addition, the positive electrode active material (300) may include the transition metal layer including the nickel metal and the manganese metal, which are alternately and repeatedly laminated, and the lithium layer including the lithium metal. The +2 ions of the nickel metal are mixed within the lithium layer, and the dopant is doped within the transition metal layer, so that the positive electrode active material (300) may include the superlattice.

[0097] Accordingly, when the positive electrode active material (300) is applied to the lithium secondary battery, the initial capacity and capacity retention rate for charge / discharge cycles of the lithium secondary battery can be optimized.

[0098]

[0099] Hereinafter, specific experimental examples and characteristic evaluation results of positive electrode active materials according to embodiments of the present invention are described.

[0100]

[0101] Precursor of cathode active material according to experimental example

[0102] NiSO as a nickel precursor 4ㆍ 6H2O was prepared, and MnSO was used as a manganese precursor. 4ㆍ 5H2O was prepared.

[0103] The nickel precursor and the manganese precursor were mixed in a ratio of 95:5 to prepare a transition metal precursor, a sulfate transition metal precursor (2M). Then, ammonia (3M) and sodium hydroxide (5M) were provided to the transition metal precursor, and a coprecipitation reaction was performed under coprecipitation conditions (nitrogen atmosphere, 45.5°C, pH 11, stirring speed 900 rpm, reaction time 24 hours) to prepare nickel manganese hydroxide (Ni) as a cathode active material precursor. 0.95 Mn 0.05 (OH)2) was prepared.

[0104]

[0105] Positive electrode active material according to Experimental Example 1-1

[0106] An example of a cathode active material precursor (Ni) according to an experimental example 0.95 Mn 0.05 (OH)2) was prepared, and LiOH was used as a lithium salt. ㆍ H2O was prepared, and Nb was prepared as a dopant material.

[0107] The above-mentioned positive electrode active material precursor, lithium salt, and dopant material were provided in a mortar and pestle at a ratio of 1.03:1.00:0.01, mixed first with a mortar and pestle for 10 minutes, and then mixed secondarily with a Thinky Mixer for 6 minutes, thereby preparing a preliminary positive electrode active material.

[0108] The above preliminary cathode active material was provided to a reactor within a heat treatment device, and while supplying oxygen to the reactor at a rate of 0.6 L / min, the temperature of the reactor was increased at a rate of 2°C / min to 500°C, followed by heat treatment for 5 hours. Thereafter, the set firing temperature of the heat treatment device was set so that the temperature of the reactor reached the target firing temperature of 725°C, and the temperature of the reactor was increased from 500°C to 725°C at a rate of 2°C / min, followed by firing at 725°C for 10 hours, thereby producing a cathode active material.

[0109]

[0110] Positive electrode active material according to Experimental Example 1-2

[0111] A cathode active material was manufactured in the same manner as Experimental Example 1-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0112]

[0113] Positive electrode active material according to Experimental Example 1-3

[0114] A cathode active material was manufactured in the same manner as Experimental Example 1-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0115]

[0116] Positive electrode active material according to Experimental Example 1-4

[0117] A cathode active material was manufactured in the same manner as Experimental Example 1-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0118]

[0119] Positive electrode active material according to Experimental Example 2-1

[0120] The cathode active material was manufactured in the same manner as in Experimental Example 1-1, except that Ti was prepared as a dopant material.

[0121]

[0122] Positive electrode active material according to Experimental Example 2-2

[0123] A cathode active material was manufactured in the same manner as Experimental Example 2-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 730°C.

[0124]

[0125] Positive electrode active material according to Experimental Example 2-3

[0126] A cathode active material was manufactured in the same manner as Experimental Example 2-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0127]

[0128] Positive electrode active material according to Experimental Example 2-4

[0129] A cathode active material was manufactured in the same manner as Experimental Example 2-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0130]

[0131] Positive electrode active material according to Experimental Example 2-5

[0132] A cathode active material was manufactured in the same manner as Experimental Example 2-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0133]

[0134] Positive electrode active material according to Experimental Example 3-1

[0135] A cathode active material was manufactured in the same manner as Experimental Example 1-1, except that Zr was prepared as a dopant material and the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 700°C.

[0136]

[0137] Positive electrode active material according to Experimental Example 3-2

[0138] A cathode active material was manufactured in the same manner as Experimental Example 3-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 725°C.

[0139]

[0140] Positive electrode active material according to Experimental Example 3-3

[0141] A cathode active material was manufactured in the same manner as Experimental Example 3-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0142]

[0143] Positive electrode active material according to Experimental Example 3-4

[0144] A cathode active material was manufactured in the same manner as Experimental Example 3-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0145]

[0146] Positive electrode active material according to Experimental Example 3-5

[0147] A cathode active material was manufactured in the same manner as Experimental Example 3-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0148]

[0149] Positive electrode active material according to Experimental Example 4-1

[0150] A cathode active material was manufactured in the same manner as in Experimental Example 1-1, except that Hf was prepared as a dopant material.

[0151]

[0152] Positive electrode active material according to Experimental Example 4-2

[0153] A cathode active material was manufactured in the same manner as Experimental Example 4-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0154]

[0155] Positive electrode active material according to Experimental Example 4-3

[0156] A cathode active material was manufactured in the same manner as Experimental Example 4-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0157]

[0158] Positive electrode active material according to Experimental Example 4-4

[0159] A cathode active material was manufactured in the same manner as Experimental Example 4-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0160]

[0161] Positive electrode active material according to Experimental Example 5-1

[0162] A cathode active material was manufactured in the same manner as in Experimental Example 1-1, except that Ta was prepared as a dopant material.

[0163]

[0164] Positive electrode active material according to Experimental Example 5-2

[0165] A cathode active material was manufactured in the same manner as Experimental Example 5-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0166]

[0167] Positive electrode active material according to Experimental Example 5-3

[0168] A cathode active material was manufactured in the same manner as Experimental Example 5-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0169]

[0170] Positive electrode active material according to Experimental Example 5-4

[0171] A cathode active material was manufactured in the same manner as Experimental Example 5-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0172]

[0173] Positive electrode active material according to Experimental Example 5-5

[0174] A cathode active material was manufactured in the same manner as Experimental Example 5-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 825°C.

[0175]

[0176] Positive electrode active material according to Experimental Example 6-1

[0177] A cathode active material was manufactured in the same manner as in Experimental Example 1-1, except that W was prepared as a dopant material.

[0178]

[0179] Positive electrode active material according to Experimental Example 6-2

[0180] A cathode active material was manufactured in the same manner as Experimental Example 6-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0181]

[0182] Positive electrode active material according to Experimental Example 6-3

[0183] A cathode active material was manufactured in the same manner as Experimental Example 6-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0184]

[0185] Positive electrode active material according to Experimental Example 6-4

[0186] A cathode active material was manufactured in the same manner as Experimental Example 6-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0187]

[0188] Positive electrode active material according to Experimental Example 6-5

[0189] A cathode active material was manufactured in the same manner as in Experimental Example 6-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 825°C.

[0190]

[0191] Positive electrode active material according to Experimental Example 6-6

[0192] A cathode active material was manufactured in the same manner as Experimental Example 6-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was 900°C, which is the target firing temperature.

[0193]

[0194] Positive electrode active material according to Experimental Example 7-1

[0195] A cathode active material was manufactured in the same manner as Experimental Example 1-1, except that Mo was prepared as a dopant material and the set sintering temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target sintering temperature of 700°C.

[0196]

[0197] Positive electrode active material according to Experimental Example 7-2

[0198] A cathode active material was manufactured in the same manner as Experimental Example 7-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was 725°C, which is the target firing temperature.

[0199]

[0200] Positive electrode active material according to Experimental Example 7-3

[0201] A cathode active material was manufactured in the same manner as Experimental Example 7-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was 730°C, which is the target firing temperature.

[0202]

[0203] Positive electrode active material according to Experimental Example 7-4

[0204] A cathode active material was manufactured in the same manner as Experimental Example 7-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0205]

[0206] Positive electrode active material according to Experimental Example 7-5

[0207] A cathode active material was manufactured in the same manner as Experimental Example 7-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0208]

[0209] Positive electrode active material according to Experimental Example 7-6

[0210] A cathode active material was manufactured in the same manner as Experimental Example 7-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0211]

[0212] Positive electrode active material according to comparative example 1-1

[0213] A cathode active material was manufactured in the same manner as in Experimental Example 1-1, except that a preliminary cathode active material was manufactured by mixing a cathode active material precursor and a lithium salt in a ratio of 1.03:1.00 without providing a dopant material.

[0214]

[0215] Positive electrode active material according to comparative example 1-2

[0216] A cathode active material was manufactured in the same manner as in Comparative Example 1-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 750°C.

[0217]

[0218] Positive electrode active material according to comparative example 1-3

[0219] A cathode active material was manufactured in the same manner as in Comparative Example 1-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 775°C.

[0220]

[0221] Positive electrode active material according to comparative example 1-4

[0222] A cathode active material was manufactured in the same manner as in Comparative Example 1-1, except that the set firing temperature of the heat treatment equipment was set so that the temperature of the reactor in the heat treatment equipment was the target firing temperature of 800°C.

[0223] Category Target Firing temperature (℃) Dopant material Comparison Example 1-1725-Comparison Example 1-2750-Comparison Example 1-3775-Comparison Example 1-4800-Experiment Example 1-1725NbExperiment Example 1-2750NbExperiment Example 1-3775NbExperiment Example 1-4800NbExperiment Example 2-1725TiExperiment Example 2-2730TiExperiment Example 2-3750TiExperiment Example 2-4775TiExperiment Example 2-5800TiExperiment Example 3-1700ZrExperiment Example 3-2725ZrExperiment Example 3-3750ZrExperiment Example 3-4775ZrExperiment Example 3-5800ZrExperiment Example 4-1725HfExperiment Example 4-2750HfExperiment Example 4-3775HfExperiment Example 4-4800Hf Experiment Example 5-1725Ta Experiment Example 5-2750Ta Experiment Example 5-3775Ta Experiment Example 5-4800Ta Experiment Example 5-5825Ta Experiment Example 6-1725W Experiment Example 6-2750W Experiment Example 6-3775W Experiment Example 6-4800W Experiment Example 6-5825W Experiment Example 6-6900W Experiment Example 7-1700Mo Experiment Example 7-2725Mo Experiment Example 7-3730Mo Experiment Example 7-4750Mo Experiment Example 7-5775Mo Experiment Example 7-6800Mo

[0224]

[0225] Figure 8 is a graph for comparing the set firing temperature of the heat treatment equipment and the actual temperature within the heat treatment equipment according to an experimental example of the present invention.

[0226] Referring to (a) of Fig. 8, the actual temperature of the lower left region of the reactor within the heat treatment equipment was measured according to the set firing temperature of the heat treatment equipment according to the experimental example. Referring to (b) of Fig. 8, the actual temperature of the lower right region of the reactor within the heat treatment equipment was measured according to the set temperature of the heat treatment equipment according to the experimental example. Referring to (c) of Fig. 8, the actual temperature of the upper right region of the reactor within the heat treatment equipment was measured according to the set temperature of the heat treatment equipment according to the experimental example. In addition, the actual temperatures of the reactor within the heat treatment equipment measured in (a) to (c) of Figs. 8 are summarized in below.

[0227] As can be seen from (a) to (c) of FIG. 8, it can be seen that the actual temperature of the reactor within the heat treatment equipment is higher than the set temperature of the heat treatment equipment.

[0228] Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the set temperature of the heat treatment equipment must be set lower than the target sintering temperature in order to heat-treat the preliminary cathode active material at the target sintering temperature.

[0229] Set temperature (℃) Actual temperature (difference value) (Lower left area) Actual temperature (difference value) (Lower right area) Actual temperature (difference value) (Upper right area) 500 518 (+18) 525 (+25) 511 (+11) 600 628 (+28) 630 (+30) 624 (+24) 650 681 (+31) 682 (+32) 678 (+28) 700 734 (+34) 734 (+34) 730 (+30) 750 786 (+36) 785 (+35) 781 (+31) 800 837 (+37) 835 (+35) 832 (+32) 900 938 (+38) 935 (+35) 930 (+30)

[0230]

[0231] Figures 9 to 11 are graphs for comparing the initial capacity and capacity retention rate for charge / discharge cycles of lithium ion batteries to which positive electrode materials according to experimental examples of the present invention are applied.

[0232] Referring to (a) and (b) of Fig. 9, the initial capacity and capacity retention rate for 200 charge / discharge cycles of lithium-ion batteries to which the positive electrode active materials according to Experimental Examples 1-1 (NM9505_Nb 725°C) to 1-4 (NM9505_Nb 800°C) were applied were measured.

[0233] As can be seen in (a) and (b) of FIG. 9, the initial capacity of the lithium ion battery to which the positive electrode active material according to Experimental Example 1-2 (NM9505_Nb 750°C) was applied is 190 mAh / g or more, and the capacity retention rate is 70% or more. Therefore, it can be seen that the optimized target sintering temperature for the Nb dopant material is 750°C.

[0234] Referring to (c) and (d) of Fig. 9, the initial capacity and capacity retention rate for 200 charge / discharge cycles of lithium ion batteries to which the positive electrode active materials according to Experimental Example 2-1 (NM9505_Ti 725°C) to Experimental Example 2-5 (NM9505_Ti 800°C) were applied were measured.

[0235] As can be seen in (c) and (d) of Fig. 9, the initial capacity of the lithium ion battery to which the positive electrode active material according to Experimental Example 2-2 (NM9505_Ti 730°C) was applied is 190 mAh / g or more, and the capacity retention rate is 70% or more. Therefore, it can be seen that the optimized target sintering temperature for the Ti dopant material is 730°C.

[0236] Referring to (e) and (f) of FIG. 9, the initial capacity and capacity retention rate for 200 charge / discharge cycles of lithium ion batteries to which the positive electrode active materials according to Experimental Examples 3-1 (NM9505_Zr 700°C) to 3-5 (NM9505_Zr 800°C) were applied were measured.

[0237] As can be seen in (e) and (f) of FIG. 9, the initial capacity of the lithium ion battery to which the positive electrode active material according to Experimental Example 3-2 (NM9505_Zr 725°C) was applied is 190 mAh / g or more, and the capacity retention rate is 70% or more. Therefore, it can be seen that the optimized target sintering temperature for the Zr dopant material is 725°C.

[0238] Referring to (a) and (b) of Fig. 10, the initial capacity and capacity retention rate for 200 charge / discharge cycles of lithium ion batteries to which the positive electrode active materials according to Experimental Example 4-1 (NM9505_Hf 725°C) to Experimental Example 4-4 (NM9505_Hf 800°C) were applied were measured.

[0239] As can be seen from (a) and (b) of Fig. 10, the initial capacity of the lithium ion battery to which the positive electrode active material according to Experimental Example 4-2 (NM9505_Hf 750°C) was applied is 190 mAh / g or more, and the capacity retention rate is 70% or more. Therefore, it can be seen that the optimized target sintering temperature for the Hf dopant material is 750°C.

[0240] Referring to (c) and (d) of Fig. 10, the initial capacity and capacity retention rate for 200 charge / discharge cycles of lithium ion batteries to which the positive electrode active materials according to Experimental Example 5-1 (NM9505_Ta 725°C) to Experimental Example 5-5 (NM9505_Ta 825°C) were applied were measured.

[0241] As can be seen in (c) and (d) of Fig. 10, the initial capacity of the lithium ion battery to which the positive electrode active material according to Experimental Example 5-3 (NM9505_Ta 775°C) was applied is 190 mAh / g or more, and the capacity retention rate is 70% or more. Therefore, it can be seen that the optimized target sintering temperature for the Ta dopant material is 775°C.

[0242] Referring to (e) and (f) of Fig. 10, the initial capacity and capacity retention rate for 200 charge / discharge cycles of lithium ion batteries to which the positive electrode active materials according to Experimental Example 6-1 (NM9505_W 725°C) to Experimental Example 6-6 (NM9505_W 900°C) were applied were measured.

[0243] As can be seen from (e) and (f) of FIG. 10, the initial capacity of the lithium ion battery to which the positive electrode active material according to Experimental Example 6-5 (NM9505_W 825°C) was applied is 190 mAh / g or more, and the capacity retention rate is 70% or more. Therefore, it can be seen that the optimized target sintering temperature for the W dopant material is 825°C.

[0244] Referring to (a) and (b) of Fig. 11, the initial capacity and capacity retention rate for 200 charge / discharge cycles of lithium ion batteries to which the positive electrode active materials according to Experimental Examples 7-1 (NM9505_Mo 700°C) to 7-6 (NM9505_Mo 800°C) were applied were measured.

[0245] As can be seen from (a) and (b) of Fig. 11, the initial capacity of the lithium ion battery to which the positive electrode active material according to Experimental Example 7-3 (NM9505_Mo 730°C) was applied is 190 mAh / g or more, and the capacity retention rate is 70% or more. Therefore, it can be seen that the optimized target sintering temperature for the Mo dopant material is 730°C.

[0246]

[0247] Fig. 12 is a table for comparing the results of XRD analysis of positive electrode active materials according to experimental examples of the present invention, and Figs. 13 and 14 are graphs for comparing the correlation between the performance of lithium-ion batteries to which positive electrode active materials according to experimental examples of the present invention are applied and the grain size of the positive electrode active materials.

[0248] Referring to Fig. 12, the cathode active materials according to Experimental Example 1-2 (Nb 750), Experimental Example 2-2 (Ti 730), Experimental Example 3-2 (Zr 725), Experimental Example 4-2 (Hf 750), Experimental Example 4-3 (Hf 775), Experimental Example 5-3 (Ta 775), Experimental Example 5-4 (Ta 800), Experimental Example 6-2 (W 750), Experimental Example 6-3 (W 775), Experimental Example 6-4 (W 800), Experimental Example 6-5 (W 825), Experimental Example 7-2 (Mo 725), and Experimental Example 7-3 (Mo 730) were analyzed by XRD Rietveld refinement and summarized in a table.

[0249] As can be seen in Fig. 12, the grain size of the cathode active materials according to Experimental Example 1-1 (Nb 750), Experimental Example 2-2 (Ti 730), Experimental Example 3-2 (Zr 725), Experimental Example 4-2 (Hf 750), Experimental Example 5-3 (Ta 775), Experimental Example 6-5 (W 825), and Experimental Example 7-3 (Mo 730), which were manufactured by heat treatment at the optimized target sintering temperature for each dopant material (Nb, Ti, Zr, Hf, Ta, W, Mo) as described in Figs. 9 to 11, is 40 nm to 60 nm.

[0250] Referring to (a) of Fig. 13, the capacity retention rate for 200 charge / discharge cycles of lithium ion batteries to which the positive electrode active materials according to Experimental Examples 1-1 to 7-6 were applied as measured in Figs. 9 to 11, and the correlation between the grain size of the positive electrode active materials according to Experimental Examples 1-1 to 7-6 are shown in a graph. Referring to (b) of Fig. 13, the initial capacity of lithium ion batteries to which the positive electrode active materials according to Experimental Examples 1-1 to 7-6 were applied as measured in Figs. 9 to 11, and the correlation between the grain size of the positive electrode active materials according to Experimental Examples 1-1 to 7-6 are shown in a graph.

[0251] As can be seen in (a) and (b) of Fig. 13, as the grain size of the positive electrode active material according to the experimental examples increases, the capacity retention rate of the lithium ion battery to which the positive electrode active material according to the experimental examples is applied decreases. In addition, when the grain size of the positive electrode active material according to the experimental examples is 40 nm or more, it can be seen that the initial capacity of the lithium ion battery to which the positive electrode active material according to the experimental examples is applied is 180 mAh / g or more.

[0252] Referring to (a) of Fig. 14, the correlation between the unit cell volume of the positive electrode active material according to Experimental Examples 1-1 to 7-6 described in Figs. 9 to 11 and the grain size of the positive electrode active material according to Experimental Examples 1-1 to 7-6 is shown in a graph. Referring to (b) of Fig. 14, the peak value (I) corresponding to the (003) plane for the positive electrode active material according to Experimental Examples 1-1 to 7-6 described in Figs. 9 to 11 is shown. (003) ) and the peak value corresponding to (104) surface (I (104) ) ratio (I (003) / I (104) ), and the correlation of the grain size of the positive electrode active material according to Experimental Examples 1-1 to 7-6 is shown in a graph. And, I according to Experimental Examples 1-1 to 7-6 (003) / I (104) And the Grain Size is summarized in below.

[0253] As can be seen from (a) and (b) of Fig. 14, when the grain size of the positive electrode active material according to the experimental examples is 60 nm or less, it can be seen that the unit cell volume of the positive electrode active material is formed uniformly. And, when the grain size of the positive electrode active material according to the experimental examples is 40 nm or more and 60 nm or less, I (003) / I (104)It can be seen that the value is greater than 1.0 and less than 1.1. In this case, it can be seen that the initial capacity and the capacity retention rate for the charge / discharge cycle of the lithium ion battery to which the positive electrode active material is applied are improved. In contrast, when the Grain Size of the positive electrode active material is 35 nm or less, it can be seen that the initial capacity of the lithium ion battery to which the positive electrode active material is applied is reduced. On the other hand, when the Grain Size of the positive electrode active material is 70 nm or more, it can be seen that the capacity retention rate for the charge / discharge cycle of the lithium ion battery to which the positive electrode active material is applied is reduced.

[0254] Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the method for manufacturing a cathode active material by firing a preliminary cathode active material at a target firing temperature optimized for each dopant material is a method for controlling the grain size of the cathode active material to be 40 nm or more and 60 nm or less, thereby improving the initial capacity of a lithium-ion battery to which the cathode active material is applied and the capacity retention rate for a charge / discharge cycle.

[0255] Target firing temperature (℃)I (003) / I (104)Grain Size (nm) Dopant Material Experimental Example 1-17250.74624.8Nb Experimental Example 1-27501.00241.7Nb Experimental Example 1-37751.230103.4Nb Experimental Example 1-48001.164116.9Nb Experimental Example 2-17250.88433.0Ti Experimental Example 2-27301.04342.8Ti Experimental Example 2-37501.31594.6Ti Experimental Example 2-47751.219105.5Ti Experimental Example 2-58001.150118.6Ti Experimental Example 3-17000.79922.8Zr Experimental Example 3-27251.06038.7Zr Experimental Example 3-37501.20694.9Zr Experimental Example 3-47751.263114.6Zr Experimental Example 3-58001.320123.0Zr Experimental Example 4-17250.80727.7Hf Experimental Example 4-27501.01441.9Hf Experimental Example 4-37751.00649.2Hf Experimental Example 4-48001.175130.9Hf Experimental Example 5-17250.85324.2Ta Experimental Example 5-27500.86227.0Ta Experimental Example 5-37751.00738.4Ta Experimental Example 5-48001.01559.3Ta Experimental Example 5-58251.12283.2Ta Experimental Example 6-17250.88222.4W Experimental Example 6-27501.03142.3W Experimental Example 6-37751.00442.3W Experimental Example 6-48001.03555.0W Experimental Example 6-58251.07863.1W Experimental Example 6-69001.065114.7W Experimental Example 7-17000.76521.7Mo Experimental Example 7-27251.00340.6Mo Experimental Example 7-37301.04948.3Mo Experimental Example 7-47501.10166.5Mo Experimental Example 7-57751.14286.7Mo Experimental Example 7-68001.280101.9Mo

[0256]

[0257] Fig. 15 is a graph for comparing WH Plots of positive electrode active materials according to comparative examples of the present invention, and Figs. 16 to 22 are graphs for comparing WH Plots of positive electrode active materials according to experimental examples of the present invention.

[0258] Referring to (a) of Fig. 15, using the XRD analysis results for the positive electrode active material according to Comparative Example 1-1 (Raw 725°C), a WH Plot for the positive electrode active material according to Comparative Example 1-1 (Raw 725°C) is shown. Referring to (b) of Fig. 15, using the XRD analysis results for the positive electrode active material according to Comparative Example 1-2 (Raw 750°C), a WH Plot for the positive electrode active material according to Comparative Example 1-2 (Raw 750°C) is shown. Referring to (c) of Fig. 15, using the XRD analysis results for the positive electrode active material according to Comparative Example 1-3 (Raw 775°C), a WH Plot for the positive electrode active material according to Comparative Example 1-3 (Raw 775°C) is shown. Referring to (d) of Fig. 15, the WH Plot for the positive electrode active material according to Comparative Example 1-4 (Raw 800°C) is shown using the XRD analysis results for the positive electrode active material according to Comparative Example 1-4 (Raw 800°C). Then, the slope for the WH Plot in (a) to (d) of Fig. 15 is calculated and summarized in below.

[0259] As can be seen from (a) to (d) of FIG. 15, as the target sintering temperature for the preliminary cathode active material without doping material increases, the growth of the particles of the produced cathode active material becomes more uniform and the particle orientation can become consistent. Accordingly, the stress applied to the crystal structure of the cathode active material is reduced, and it can be seen that the slope on the WH Plot is reduced.

[0260] Classification Target Firing Temperature Slope Graph Legend Display Comparison Example 1-17250.00221 Raw 725℃ Comparison Example 1-27500.00202 Raw 750℃ Comparison Example 1-37750.00198 Raw 775℃ Comparison Example 1-48000.00178 Raw 800℃

[0261] Referring to (a) of Fig. 16, using the XRD analysis results for the positive electrode active material according to Experimental Example 1-1 (Nb 725°C), a WH Plot for the positive electrode active material according to Experimental Example 1-1 (Nb 725°C) is shown. Referring to (b) of Fig. 16, using the XRD analysis results for the positive electrode active material according to Experimental Example 1-2 (Nb 750°C), a WH Plot for the positive electrode active material according to Experimental Example 1-2 (Nb 750°C) is shown. Referring to (c) of Fig. 16, using the XRD analysis results for the positive electrode active material according to Experimental Example 1-3 (Nb 775°C), a WH Plot for the positive electrode active material according to Experimental Example 1-3 (Nb 775°C) is shown. Referring to (d) of Fig. 16, the WH Plot for the positive electrode active material according to Experimental Example 1-4 (Nb 800°C) is shown using the XRD analysis results for the positive electrode active material according to Experimental Example 1-4 (Nb 800°C). Then, the slope for the WH Plot in (a) to (d) of Fig. 16 is calculated and summarized in below.

[0262] As can be seen from (a) to (d) of Fig. 16, the slope of the WH plot of the positive electrode active material according to Experimental Example 1-2 is the largest. This factor is interpreted to be due to the fact that stress was applied to the (104) plane during the sintering process of the preliminary positive electrode active material. Accordingly, it can be seen that the particles of the positive electrode active material grew toward the (003) plane among the (003) plane and the (104) plane.

[0263] Classification Target Firing Temperature Slope Graph Legend Display Experimental Example 1-17250.00194Nb 725℃ Experimental Example 1-27500.00226Nb 750℃ Experimental Example 1-37750.00222Nb 775℃ Experimental Example 1-48000.00194Nb 800℃

[0264] Referring to (a) of Fig. 17, using the XRD analysis results for the positive electrode active material according to Experimental Example 2-1 (Ti 725°C), a WH Plot for the positive electrode active material according to Experimental Example 2-1 (Ti 725°C) is shown. Referring to (b) of Fig. 17, using the XRD analysis results for the positive electrode active material according to Experimental Example 2-2 (Ti 730°C), a WH Plot for the positive electrode active material according to Experimental Example 2-2 (Ti 730°C) is shown. Referring to (c) of Fig. 17, using the XRD analysis results for the positive electrode active material according to Experimental Example 2-3 (Ti 750°C), a WH Plot for the positive electrode active material according to Experimental Example 2-3 (Ti 750°C) is shown. Referring to (d) of Fig. 17, using the XRD analysis results for the positive electrode active material according to Experimental Example 2-4 (Ti 775°C), a WH Plot for the positive electrode active material according to Experimental Example 2-4 (Ti 775°C) is shown. Referring to (e) of Fig. 17, using the XRD analysis results for the positive electrode active material according to Experimental Example 2-5 (Ti 800°C), a WH Plot for the positive electrode active material according to Experimental Example 2-5 (Ti 800°C) is shown. In addition, the slopes for the WH Plots in (a) to (e) of Fig. 17 were calculated and summarized in below.

[0265] As can be seen from (a) to (e) of Fig. 17, the slope of the WH plot of the positive electrode active material according to Experimental Example 2-2 is the largest. This factor is interpreted to be due to the fact that stress was applied to the (104) plane during the sintering process of the preliminary positive electrode active material. Accordingly, it can be seen that the particles of the positive electrode active material grew toward the (003) plane among the (003) plane and the (104) plane.

[0266] Classification Target Firing Temperature Slope Graph Legend Display Experimental Example 2-17250.00253Ti 725℃ Experimental Example 2-27300.00259Ti 730℃ Experimental Example 2-37500.00213Ti 750℃ Experimental Example 2-47750.00202Ti 775℃ Experimental Example 2-58000.00223Ti 800℃

[0267] Referring to (a) of Fig. 18, using the XRD analysis results for the positive electrode active material according to Experimental Example 3-1 (Zr 700°C), a WH Plot for the positive electrode active material according to Experimental Example 3-1 (Zr 700°C) is shown. Referring to (b) of Fig. 18, using the XRD analysis results for the positive electrode active material according to Experimental Example 3-2 (Zr 725°C), a WH Plot for the positive electrode active material according to Experimental Example 3-2 (Zr 725°C) is shown. Referring to (c) of Fig. 18, using the XRD analysis results for the positive electrode active material according to Experimental Example 3-3 (Zr 750°C), a WH Plot for the positive electrode active material according to Experimental Example 3-3 (Zr 750°C) is shown. Referring to (d) of Fig. 18, using the XRD analysis results for the positive electrode active material according to Experimental Example 3-4 (Zr 775°C), a WH Plot for the positive electrode active material according to Experimental Example 3-4 (Zr 775°C) is shown. Referring to (e) of Fig. 18, using the XRD analysis results for the positive electrode active material according to Experimental Example 3-5 (Zr 800°C), a WH Plot for the positive electrode active material according to Experimental Example 3-5 (Zr 800°C) is shown. In addition, the slopes for the WH Plots in (a) to (e) of Fig. 18 were calculated and summarized in below.

[0268] As can be seen from (a) to (e) of Fig. 18, the slope of the WH plot of the positive electrode active material according to Experimental Example 3-2 is the largest. This factor is interpreted to be due to the fact that stress was applied to the (104) plane during the sintering process of the preliminary positive electrode active material. Accordingly, it can be seen that the particles of the positive electrode active material grew toward the (003) plane among the (003) plane and the (104) plane.

[0269] Classification Target Firing Temperature Slope Graph Legend Display Experimental Example 3-17000.00225Zr 700℃ Experimental Example 3-27250.00240Zr 725℃ Experimental Example 3-37500.00210Zr 750℃ Experimental Example 3-47750.00182Zr 775℃ Experimental Example 3-58000.00149Zr 800℃

[0270] Referring to (a) of Fig. 19, using the XRD analysis results for the positive electrode active material according to Experimental Example 4-1 (Hf 725°C), a WH Plot for the positive electrode active material according to Experimental Example 4-1 (Hf 725°C) is shown. Referring to (b) of Fig. 19, using the XRD analysis results for the positive electrode active material according to Experimental Example 4-2 (Hf 750°C), a WH Plot for the positive electrode active material according to Experimental Example 4-2 (Hf 750°C) is shown. Referring to (c) of Fig. 19, using the XRD analysis results for the positive electrode active material according to Experimental Example 4-3 (Hf 775°C), a WH Plot for the positive electrode active material according to Experimental Example 4-3 (Hf 775°C) is shown. Referring to (d) of Fig. 19, the WH Plot for the positive electrode active material according to Experimental Example 4-4 (Hf 800°C) is shown using the XRD analysis results for the positive electrode active material according to Experimental Example 4-4 (Hf 800°C). Then, the slope for the WH Plot in (a) to (d) of Fig. 19 is calculated and summarized in below.

[0271] As can be seen from (a) to (d) of Fig. 19, the slope of the WH plot of the positive electrode active material according to Experimental Example 4-2 is the largest. This factor is interpreted to be due to the fact that stress was applied to the (104) plane during the sintering process of the preliminary positive electrode active material. Accordingly, it can be seen that the particles of the positive electrode active material grew toward the (003) plane among the (003) plane and the (104) plane.

[0272] Classification Target Firing Temperature Slope Graph Legend Display Experimental Example 4-17250.00292Hf 725℃ Experimental Example 4-27500.00310Hf 750℃ Experimental Example 4-37770.00225Hf 775℃ Experimental Example 4-48000.00193Hf 800℃

[0273] Referring to (a) of Fig. 20, using the XRD analysis results for the positive electrode active material according to Experimental Example 5-1 (Ta 725°C), a WH Plot for the positive electrode active material according to Experimental Example 5-1 (Ta 725°C) is shown. Referring to (b) of Fig. 20, using the XRD analysis results for the positive electrode active material according to Experimental Example 5-2 (Ta 750°C), a WH Plot for the positive electrode active material according to Experimental Example 5-2 (Ta 750°C) is shown. Referring to (c) of Fig. 20, using the XRD analysis results for the positive electrode active material according to Experimental Example 5-3 (Ta 775°C), a WH Plot for the positive electrode active material according to Experimental Example 5-3 (Ta 775°C) is shown. Referring to (d) of Fig. 20, using the XRD analysis results for the positive electrode active material according to Experimental Example 5-4 (Ta 800°C), a WH Plot for the positive electrode active material according to Experimental Example 5-4 (Ta 800°C) is shown. Referring to (e) of Fig. 20, using the XRD analysis results for the positive electrode active material according to Experimental Example 5-5 (Zr 825°C), a WH Plot for the positive electrode active material according to Experimental Example 5-5 (Zr 825°C) is shown. In addition, the slopes for the WH Plots in (a) to (e) of Fig. 20 were calculated and summarized in below.

[0274] As can be seen from (a) to (e) of Fig. 20, the slope of the WH plot of the positive electrode active material according to Experimental Example 5-3 is the largest. This factor is interpreted to be due to the fact that stress was applied to the (104) plane during the sintering process of the preliminary positive electrode active material. Accordingly, it can be seen that the particles of the positive electrode active material grew toward the (003) plane among the (003) plane and the (104) plane.

[0275] Classification Target Firing Temperature Slope Graph Legend Display Experimental Example 5-17250.00254Ta 725℃ Experimental Example 5-27500.00246Ta 750℃ Experimental Example 5-37750.00260Ta 775℃ Experimental Example 5-48000.00247Ta 800℃ Experimental Example 5-58250.00237Ta 825℃

[0276] Referring to (a) of Fig. 21, using the XRD analysis results for the positive electrode active material according to Experimental Example 6-1 (W 725°C), a WH Plot for the positive electrode active material according to Experimental Example 6-1 (W 725°C) is shown. Referring to (b) of Fig. 21, using the XRD analysis results for the positive electrode active material according to Experimental Example 6-2 (W 750°C), a WH Plot for the positive electrode active material according to Experimental Example 6-2 (W 750°C) is shown. Referring to (c) of Fig. 21, using the XRD analysis results for the positive electrode active material according to Experimental Example 6-3 (W 775°C), a WH Plot for the positive electrode active material according to Experimental Example 6-3 (W 775°C) is shown. Referring to (d) of Fig. 21, using the XRD analysis results for the positive electrode active material according to Experimental Example 6-4 (W 800°C), a WH Plot for the positive electrode active material according to Experimental Example 6-4 (W 800°C) is shown. Referring to (e) of Fig. 21, using the XRD analysis results for the positive electrode active material according to Experimental Example 6-5 (W 825°C), a WH Plot for the positive electrode active material according to Experimental Example 6-5 (W 825°C) is shown. Referring to (f) of Fig. 21, using the XRD analysis results for the positive electrode active material according to Experimental Example 6-6 (W 900°C), a WH Plot for the positive electrode active material according to Experimental Example 6-6 (W 900°C) is shown. In addition, the slopes for the WH Plots in (a) to (f) of Fig. 21 were calculated and summarized in below.

[0277] As can be seen from (a) to (f) of Fig. 21, the slope of the WH plot of the positive electrode active material according to Experimental Example 6-5 is the largest. This factor is interpreted to be due to the fact that stress was applied to the (104) plane during the sintering process of the preliminary positive electrode active material. Accordingly, it can be seen that the particles of the positive electrode active material grew toward the (003) plane among the (003) plane and the (104) plane.

[0278] Classification Target Firing Temperature Slope Graph Legend Display Experimental Example 6-17250.00236W 725℃ Experimental Example 6-27500.00232W 750℃ Experimental Example 6-37750.00200W 775℃ Experimental Example 6-48000.00199W 800℃ Experimental Example 6-58250.00246W 825℃ Experimental Example 6-69000.00217W 900℃

[0279] Referring to (a) of Fig. 22, using the XRD analysis results for the positive electrode active material according to Experimental Example 7-1 (Mo 700°C), a WH Plot for the positive electrode active material according to Experimental Example 7-1 (Mo 700°C) is shown. Referring to (b) of Fig. 22, using the XRD analysis results for the positive electrode active material according to Experimental Example 7-2 (Mo 725°C), a WH Plot for the positive electrode active material according to Experimental Example 7-2 (Mo 725°C) is shown. Referring to (c) of Fig. 22, using the XRD analysis results for the positive electrode active material according to Experimental Example 7-3 (Mo 730°C), a WH Plot for the positive electrode active material according to Experimental Example 7-3 (Mo 730°C) is shown. Referring to (d) of Fig. 22, using the XRD analysis results for the positive electrode active material according to Experimental Example 7-4 (Mo 750°C), a WH Plot for the positive electrode active material according to Experimental Example 7-4 (Mo 750°C) is shown. Referring to (e) of Fig. 22, using the XRD analysis results for the positive electrode active material according to Experimental Example 7-5 (Mo 775°C), a WH Plot for the positive electrode active material according to Experimental Example 7-5 (Mo 775°C) is shown. Referring to (f) of Fig. 22, using the XRD analysis results for the positive electrode active material according to Experimental Example 7-6 (Mo 800°C), a WH Plot for the positive electrode active material according to Experimental Example 7-6 (Mo 800°C) is shown. In addition, the slopes for the WH Plots in (a) to (f) of Fig. 22 were calculated and summarized in below.

[0280] As can be seen from (a) to (f) of Fig. 22, the slope of the WH plot of the positive electrode active material according to Experimental Example 7-3 is the largest. This factor is interpreted to be due to the fact that stress was applied to the (104) plane during the sintering process of the preliminary positive electrode active material. Accordingly, it can be seen that the particles of the positive electrode active material grew toward the (003) plane among the (003) and (104) planes.

[0281] Classification Target Firing Temperature (℃) Slope Graph Legend Display Experimental Example 7-17000.00272Mo 700℃ Experimental Example 7-27250.00272Mo 725℃ Experimental Example 7-37300.00285Mo 730℃ Experimental Example 7-47500.00234Mo 750℃ Experimental Example 7-57750.00228Mo 775℃ Experimental Example 7-68000.00216Mo 800℃

[0282]

[0283] Fig. 23 is an SEM photograph of a cathode active material according to Comparative Example 1-1 of the present invention, and Figs. 24 to 30 are graphs for comparing SEM photographs and EDS Mapping analysis results of cathode active materials according to experimental examples of the present invention.

[0284] Referring to Fig. 23, a cross-section of the positive electrode active material according to Comparative Example 1-1 was photographed using SEM.

[0285] As can be seen in Fig. 23, the primary particles of the positive electrode active material according to Comparative Example 1-1 have a circular shape, and it can be seen that the size of the primary particles increases from the inside of the positive electrode active material to the surface.

[0286] Referring to (a) of Fig. 24, a cross-section of the positive electrode active material according to Experimental Example 1-2 was photographed using SEM. Referring to (b) of Fig. 24, EDS Mapping analysis was performed on the dopant of the positive electrode active material according to Experimental Example 1-2.

[0287] As can be seen in (a) and (b) of Fig. 24, the surface of the positive electrode active material according to Experimental Example 1-2 has primary particles in the shape of rods, and it can be seen that the proportion of the primary particles in the shape of rods decreases from the surface to the inside of the positive electrode active material. This factor is interpreted to be due to the fact that the surface of the positive electrode active material according to Experimental Example 1-2 is doped with a higher proportion of dopant than the inside.

[0288] Referring to (a) of Fig. 25, a cross-section of the positive electrode active material according to Experimental Example 2-2 was photographed using SEM. Referring to (b) of Fig. 25, EDS Mapping was performed on the dopant of the positive electrode active material according to Experimental Example 2-2.

[0289] As can be seen in (a) and (b) of Fig. 25, the surface of the positive electrode active material according to Experimental Example 2-2 has primary particles in the shape of rods, and it can be seen that the proportion of the primary particles in the shape of rods decreases from the surface to the inside of the positive electrode active material. This factor is interpreted to be due to the fact that the surface of the positive electrode active material according to Experimental Example 2-2 is doped with a higher proportion of dopant than the inside.

[0290] Referring to (a) of Fig. 26, a cross-section of the positive electrode active material according to Experimental Example 3-2 was photographed using SEM. Referring to (b) of Fig. 26, EDS Mapping was performed on the dopant of the positive electrode active material according to Experimental Example 3-2.

[0291] As can be seen in (a) and (b) of Fig. 26, the surface of the positive electrode active material according to Experimental Example 3-2 has primary particles in the shape of rods, and it can be seen that the proportion of the primary particles in the shape of rods decreases from the surface to the inside of the positive electrode active material. This factor is interpreted to be due to the fact that the surface of the positive electrode active material according to Experimental Example 3-2 is doped with a higher proportion of dopant than the inside.

[0292] Referring to (a) of Fig. 27, a cross-section of the positive electrode active material according to Experimental Example 4-2 was photographed using SEM. Referring to (b) of Fig. 27, EDS Mapping was performed on the dopant of the positive electrode active material according to Experimental Example 4-2.

[0293] As can be seen in (a) and (b) of Fig. 27, the surface of the positive electrode active material according to Experimental Example 4-2 has primary particles in the shape of rods, and it can be seen that the proportion of the primary particles in the shape of rods decreases from the surface to the inside of the positive electrode active material. This factor is interpreted to be due to the fact that the surface of the positive electrode active material according to Experimental Example 4-2 is doped with a higher proportion of dopant than the inside.

[0294] Referring to (a) of Fig. 28, a cross-section of the positive electrode active material according to Experimental Example 5-3 was photographed using SEM. Referring to (b) of Fig. 28, EDS Mapping was performed on the dopant of the positive electrode active material according to Experimental Example 5-3.

[0295] As can be seen in (a) and (b) of Fig. 28, the surface and interior of the positive electrode active material according to Experimental Example 5-2 have similar proportions of primary particles in the form of rods. This factor is interpreted to be due to the fact that the surface and interior of the positive electrode active material according to Experimental Example 5-2 are doped with dopants at similar proportions.

[0296] Referring to (a) of Fig. 29, a cross-section of the positive electrode active material according to Experimental Example 6-5 was photographed using SEM. Referring to (b) of Fig. 29, EDS Mapping was performed on the dopant of the positive electrode active material according to Experimental Example 6-5.

[0297] As can be seen in (a) and (b) of Fig. 29, the surface and interior of the positive electrode active material according to Experimental Example 6-5 have similar proportions of primary particles in the form of rods. This factor is interpreted to be due to the fact that the surface and interior of the positive electrode active material according to Experimental Example 6-5 are doped with dopants at similar proportions.

[0298] Referring to (a) of Fig. 30, a cross-section of the positive electrode active material according to Experimental Example 7-3 was photographed using SEM. Referring to (b) of Fig. 30, EDS Mapping was performed on the dopant of the positive electrode active material according to Experimental Example 7-3.

[0299] As can be seen in (a) and (b) of Fig. 30, the surface of the positive electrode active material according to Experimental Example 7-3 has primary particles in the shape of rods, and it can be seen that the proportion of the primary particles in the shape of rods decreases from the surface to the inside of the positive electrode active material. This factor is interpreted to be due to the fact that the surface of the positive electrode active material according to Experimental Example 7-3 is doped with a higher proportion of dopant than the inside.

[0300]

[0301] Figures 31 and 32 are graphs for comparing the crystal stability of positive electrode active materials according to comparative examples and experimental examples.

[0302] Referring to (a) of Fig. 31, XRD analysis was performed on the cathode active materials according to Comparative Examples 1-1 (725°C) to 1-4 (800°C) to show the c / 3a ratio in a graph. In addition, XRD analysis was performed on the cathode active materials according to Experimental Examples 1-1 (725°C) to 1-4 (800°C) to show the c / 3a ratio in a graph.

[0303] As can be seen in (a) of Fig. 31, the c / 3a ratio of the cathode active material according to Experimental Example 2-2 (750°C) is the highest. Accordingly, it can be seen that the crystal stability of the cathode active material according to Experimental Example 2-2 (750°C) is the best. Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the method of calcining a transition metal hydroxide, a lithium salt, and a Nb dopant material at a temperature exceeding 725°C and less than 775°C is a method for improving the crystal stability of the cathode active material.

[0304] Referring to (b) of Fig. 31, XRD analysis was performed on the cathode active materials according to Comparative Examples 1-1 (725°C) to 1-4 (800°C) to show the c / 3a ratio in a graph. In addition, XRD analysis was performed on the cathode active materials according to Experimental Examples 2-1 (725°C) to 2-5 (800°C) to show the c / 3a ratio in a graph.

[0305] As can be seen in (b) of Fig. 31, the c / 3a ratio of the positive electrode active material according to Experimental Example 2-2 (730°C) is the highest. Accordingly, it can be seen that the crystal stability of the positive electrode active material according to Experimental Example 2-2 (730°C) is the best. Therefore, in the method for manufacturing a positive electrode active material according to the present invention, it can be seen that the method of calcining a transition metal hydroxide, a lithium salt, and a Ti dopant material at more than 725°C and less than 750°C is a method for improving the crystal stability of the positive electrode active material by controlling the c / 3a of the positive electrode active material to exceed 1.6459.

[0306] Referring to (c) of Fig. 31, XRD analysis was performed on the cathode active materials according to Comparative Examples 1-1 (725°C) to 1-4 (800°C) to show the c / 3a ratio in a graph. In addition, XRD analysis was performed on the cathode active materials according to Experimental Examples 3-1 (700°C) to 3-5 (800°C) to show the c / 3a ratio in a graph.

[0307] As can be seen in (c) of Fig. 31, the c / 3a ratio of the cathode active material according to Experimental Example 3-2 (725°C) is the highest. Accordingly, it can be seen that the crystal stability of the cathode active material according to Experimental Example 3-2 (725°C) is the best. Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the method of calcining a transition metal hydroxide, a lithium salt, and a Zr dopant material at a temperature exceeding 700°C and less than 750°C is a method for improving the crystal stability of the cathode active material.

[0308] Referring to (d) of Fig. 31, XRD analysis was performed on the cathode active materials according to Comparative Examples 1-1 (725°C) to 1-4 (800°C) to show the c / 3a ratio in a graph. In addition, XRD analysis was performed on the cathode active materials according to Experimental Examples 4-1 (725°C) to 4-4 (800°C) to show the c / 3a ratio in a graph.

[0309] As can be seen in (d) of Fig. 31, the c / 3a ratio of the cathode active material according to Experimental Example 4-2 (750°C) is the highest. Accordingly, it can be seen that the crystal stability of the cathode active material according to Experimental Example 4-2 (750°C) is the best. Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the method of calcining a transition metal hydroxide, a lithium salt, and a Hf dopant material at a temperature exceeding 725°C and less than 775°C is a method for improving the crystal stability of the cathode active material.

[0310] Referring to (a) of Fig. 32, XRD analysis was performed on the cathode active materials according to Comparative Examples 1-1 (725°C) to 1-4 (800°C) to present the c / 3a ratio in a graph. In addition, XRD analysis was performed on the cathode active materials according to Experimental Examples 7-1 (700°C) to 7-6 (800°C) to present the c / 3a ratio in a graph.

[0311] As can be seen in (a) of Fig. 32, the c / 3a ratio of the cathode active material according to Experimental Example 7-3 (730°C) is the highest. Accordingly, it can be seen that the crystal stability of the cathode active material according to Experimental Example 7-3 (730°C) is the best. Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the method of calcining a transition metal hydroxide, a lithium salt, and a Mo dopant material at a temperature exceeding 725°C and less than 750°C is a method for improving the crystal stability of the cathode active material.

[0312] Referring to (b) of Fig. 32, XRD analysis was performed on the cathode active materials according to Comparative Examples 1-1 (725°C) to 1-4 (800°C) to show the c / 3a ratio in a graph. In addition, XRD analysis was performed on the cathode active materials according to Experimental Examples 5-1 (725°C) to 5-5 (825°C) to show the c / 3a ratio in a graph.

[0313] As can be seen in (b) of Fig. 32, the c / 3a ratio of the cathode active material according to Experimental Example 5-3 (775°C) is the highest. Accordingly, it can be seen that the crystal stability of the cathode active material according to Experimental Example 5-3 (775°C) is the best. Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the method of calcining a transition metal hydroxide, a lithium salt, and a Ta dopant material at a temperature exceeding 750°C and less than 800°C is a method for improving the crystal stability of the cathode active material.

[0314] Referring to (c) of Fig. 32, XRD analysis was performed on the cathode active materials according to Comparative Examples 1-1 (725°C) to 1-4 (800°C) to show the c / 3a ratio in a graph. In addition, XRD analysis was performed on the cathode active materials according to Experimental Examples 6-1 (725°C) to 6-6 (900°C) to show the c / 3a ratio in a graph.

[0315] As can be seen in (c) of Fig. 32, the c / 3a ratio of the cathode active material according to Experimental Example 6-5 (825°C) is the highest. Accordingly, it can be seen that the crystal stability of the cathode active material according to Experimental Example 6-5 (823°C) is the best. Therefore, in the method for manufacturing a cathode active material according to the present invention, it can be seen that the method of calcining a transition metal hydroxide, a lithium salt, and a W dopant material at a temperature exceeding 800°C and less than 900°C is a method for improving the crystal stability of the cathode active material.

[0316] Category Target Firing temperature (℃) c / 3a Ratio Dopant Material Comparison Example 1-17251.6458-Comparison Example 1-27501.6455-Comparison Example 1-37751.6451-Comparison Example 1-48001.6452-Experimental Example 1-17251.6449NbExperimental Example 1-27501.6469NbExperimental Example 1-37751.6453NbExperimental Example 1-48001.6454NbExperimental Example 2-17251.6453TiExperimental Example 2-27301.6470TiExperimental Example 2-37501.6459TiExperimental Example 2-47751.6452TiExperimental Example 2-58001.6464TiExperimental Example 3-17001.6447Zr Experimental Example 3-27251.6465Zr Experimental Example 3-37501.6449Zr Experimental Example 3-47751.6447Zr Experimental Example 3-58001.6447Zr Experimental Example 4-17251.6457Hf Experimental Example 4-27501.6469Hf Experimental Example 4-37751.6461Hf Experimental Example 4-48001.6458Hf Experimental Example 5-17251.6459Ta Experimental Example 5-27501.6454Ta Experimental Example 5-37751.6461Ta Experimental Example 5-48001.6453Ta Experimental Example 5-58251.6457Ta Experimental Example 6-17251.6447W Experimental Example 6-27501.6456W Experimental Example 6-37751.6447W Experimental Example 6-48001.6447W Experimental Example 6-58251.6462W Experimental Example 6-69001.6439W Experimental Example 7-17001.6443Mo Experimental Example 7-27251.6449Mo Experimental Example 7-37301.6459Mo Experimental Example 7-47501.6454Mo Experimental Example 7-57751.6456Mo Experimental Example 7-68001.6458Mo

[0317]

[0318] Fig. 33 is a FIB-TEM photograph of a cathode active material according to Experiment 2-2 of the present invention, and Fig. 34 is a FIB-TEM photograph of a cathode active material according to Experimental Example 2-5 of the present invention.

[0319] Referring to (a) to (d) of Fig. 33, the cathode active material according to Experimental Example 2-2 (Ti 730°C) was photographed using FIB-TEM, and the length in the dense packing direction of the unit cell of the cathode active material was measured. Referring to (a) to (d) of Fig. 34, the cathode active material according to Experimental Example 2-5 (Ti 800°C) was photographed using FIB-TEM, and the length in the dense packing direction of the unit cell of the cathode active material was measured.

[0320] As can be seen from (a) to (d) of FIG. 33, the positive electrode active material according to Experimental Example 2-2 has a crystal structure in which the lithium layer and the transition metal layer of the positive electrode active material are alternately and repeatedly laminated. In addition, it can be seen that the divalent ion of the nickel metal of the transition metal layer of the positive electrode active material according to Experimental Example 2-2 is mixed within the lithium layer. Accordingly, it can be seen that the length of the unit cell of the positive electrode active material according to Experimental Example 2-2 in the close-packing direction is 0.40 nm. Therefore, it can be seen that the lattice structure of the positive electrode active material according to Experimental Example 2-2 is a superlattice.

[0321] As can be seen from (a) to (d) of FIG. 34, the cathode active material according to Experimental Example 2-5 has a crystal structure in which the lithium layer and the transition metal layer of the cathode active material are alternately and repeatedly laminated. In addition, it can be seen that the length of the unit cell of the cathode active material according to Experimental Example 2-5 in the close-packing direction is 0.20 nm. Therefore, it can be seen that the lattice structure of the cathode active material according to Experimental Example 2-5 is not a superlattice.

[0322]

[0323] Figures 35 to 38 are graphs for comparing the crystal structure of the positive electrode active material according to Experimental Examples 2-2 and 2-5 before and after the charge / discharge cycle of the lithium ion battery to which the positive electrode active material according to Experimental Examples 2-2 and 2-5 of the present invention is applied.

[0324] Referring to Fig. 35, after performing 200 charge / discharge cycles on the lithium ion batteries to which the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) were applied, the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) were analyzed by XRD. Referring to Fig. 36 (a), after performing 200 charge / discharge cycles on the lithium ion batteries to which the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) were applied, the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) were analyzed by XRD Rietveld refinement. Referring to (b) of Fig. 36, after performing 200 charge / discharge cycles on the lithium ion battery to which the positive electrode active material according to Experimental Example 2-5 (Ti 800°C) was applied, the positive electrode active material according to Experimental Example 2-5 (Ti 800°C) was analyzed by XRD Rietveld refinement. Referring to Fig. 37, the c / 3a ratio (black) in the XRD Rietveld refinement results of the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) measured in (a) and (b) of Fig. 36 is shown in a graph. In addition, the c / 3a ratio (orange) of the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) measured in (b) of Fig. 31 is shown in a graph. And, the data related to Figs. 35 and 36 are organized in below.

[0325] As can be seen in FIGS. 35 to 37, the cathode active material according to Experimental Example 2-2 can be seen that the unit cell volume of the cathode active material is substantially maintained after 200 charge / discharge cycles, and thus the grain size of the cathode active material is maintained. In contrast, the cathode active material according to Experimental Example 2-5 can be seen that the unit cell volume of the cathode active material changes after 200 charge / discharge cycles, and thus the grain size changes, compared to the cathode active material according to Experimental Example 2-2. In addition, the cathode active material according to Experimental Example 2-5 can be seen that the c / 3a ratio is reduced by about 3 times after 200 charge / discharge cycles, compared to the cathode active material according to Experimental Example 2-2. Therefore, it can be seen that the cathode active material according to Experimental Example 2-2 has superior crystal stability for 200 charge / discharge cycles than the cathode active material according to Experimental Example 2-5.

[0326] Categorya (Å)c (Å)c / 3a ratioUnit cell volumeI (003) / I (104) Grain size(nm)R WP Before 200 cyclesExperimental Example 2-22.87714.2151.6470101.8961.04342.84.014Experimental Example 2-52.87914.2201.6464102.0741.150118.63.967After 200 cyclesExperimental Example 2-22.88514.2201.6433102.5211.39150.99.923Experimental Example 2-52.88914.1651.6343102.3861.61166.610.499

[0327] Referring to (a) of Fig. 38, before performing 200 charge / discharge cycles of the lithium ion battery to which the positive electrode active material according to Experimental Example 2-2 (Ti 730°C) was applied, the WH plot for the positive electrode active material according to Experimental Example 2-2 (Ti 730°C) was graphically represented. Referring to (b) of Fig. 38, after performing 200 charge / discharge cycles of the lithium ion battery to which the positive electrode active material according to Experimental Example 2-2 (Ti 730°C) was applied, the WH plot for the positive electrode active material according to Experimental Example 2-2 (Ti 730°C) was graphically represented. Referring to (c) of Fig. 38, before performing 200 charge / discharge cycles of the lithium ion battery to which the positive electrode active material according to Experimental Example 2-5 (Ti 800°C) was applied, the WH plot for the positive electrode active material according to Experimental Example 2-5 (Ti 800°C) was graphically represented. Referring to (d) of Fig. 38, after performing 200 charge / discharge cycles of the lithium ion battery to which the positive electrode active material according to Experimental Example 2-5 (Ti 800°C) was applied, the WH plot for the positive electrode active material according to Experimental Example 2-5 (Ti 800°C) was graphically represented. Referring to (e) of FIG. 38, before performing 200 charge / discharge cycles of the lithium ion batteries to which the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) were applied, the slope (red) for the WH plot of the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) was shown in the graph. Then, after performing 200 charge / discharge cycles of the lithium ion batteries to which the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) were applied, the slope (blue) for the WH plot of the positive electrode active materials according to Experimental Example 2-2 (Ti 730°C) and Experimental Example 2-5 (Ti 800°C) was shown in the graph.

[0328] As can be seen from (a) to (e) of FIG. 38, the positive electrode active material according to Experimental Example 2-2 shows a decreased slope for the WH Plot after performing 200 charge / discharge cycles. In contrast, the positive electrode active material according to Experimental Example 2-5 shows an increased slope for the WH Plot after performing 200 charge / discharge cycles. This is interpreted as being due to the fact that, in the case of the positive electrode active material according to Experimental Example 2-2, a weaker stress was applied to the (104) plane of the positive electrode active material during the 200 charge / discharge cycles than before performing the 200 charge / discharge cycles. And, it is interpreted that the positive electrode active material according to Experimental Example 2-5 is caused by the fact that the primary particles of the positive electrode active material are destroyed during the 200 charge / discharge cycles, and a stronger stress is applied to the (104) plane than before performing the 200 charge / discharge cycles.

[0329]

[0330] Figure 39 is an SEM photograph of a positive electrode material according to Experimental Examples 2-2 and 2-5 of the present invention after performing a charge / discharge cycle on a lithium ion battery to which the positive electrode material according to Experimental Examples 2-2 and 2-5 of the present invention was applied.

[0331] Referring to (a) of Fig. 39, after performing 200 charge / discharge cycles on a lithium ion battery to which the positive electrode material according to Experimental Example 2-2 was applied, a photograph of the positive electrode material according to Experimental Example 2-2 was taken using an SEM. Referring to (b) of Fig. 39, after performing 200 charge / discharge cycles on a lithium ion battery to which the positive electrode material according to Experimental Example 2-5 was applied, a photograph of the positive electrode material according to Experimental Example 2-2 was taken using an SEM.

[0332] As can be seen in (a) and (b) of FIG. 39, the cathode active material according to Experimental Example 2-2 can be seen to have maintained its shape after 200 charge / discharge cycles. In contrast, the cathode active material according to Experimental Example 2-5 can be seen to have an irregular shape due to the destruction of the primary particles of the cathode active material after 200 charge / discharge cycles. Therefore, it can be seen that the cathode active material according to Experimental Example 2-2 has superior durability for charge / discharge cycles than the cathode active material according to Experimental Example 2-5.

[0333]

[0334] Figure 40 shows the temperature constant (θ) for the positive electrode active material according to Experimental Examples 2-1, 2-2, and 2-5 of the present invention. p ) and I (003) / I (104) This is a graph for comparison.

[0335] Referring to Fig. 40, the magnetic moment of the positive electrode active materials according to Experimental Example 2-1 (Ti 725°C), Experimental Example 2-2 (Ti 730°C), and Experimental Example 2-5 (Ti 800°C) was measured at each temperature. Then, using the graph of the magnetic moment of the positive electrode active materials according to each temperature of the measured Experimental Example 2-1 (Ti 725°C), Experimental Example 2-2 (Ti 730°C), and Experimental Example 2-5 (Ti 800°C) and the <Mathematical Formula 1> below, the slope was calculated by the linear fitting method, and the Curie constant (C) for the positive electrode active materials according to Experimental Example 2-1 (Ti 725°C), Experimental Example 2-2 (Ti 730°C), and Experimental Example 2-5 (Ti 800°C) in the <Mathematical Formula 1> below was calculated. p) was calculated. And, the Y-intercept value of the magnetic moment graph according to the temperature of the positive electrode active material according to Experimental Example 2-1 (Ti 725°C), Experimental Example 2-2 (Ti 730°C), and Experimental Example 2-5 (Ti 800°C) with linear fitting and the Curie constant (C) for the positive electrode active material according to Experimental Example 2-1 (Ti 725°C), Experimental Example 2-2 (Ti 730°C), and Experimental Example 2-5 (Ti 800°C) p ) by multiplying the temperature constant (θ) for the positive electrode active material according to Experimental Example 2-1 (Ti 725°C), Experimental Example 2-2 (Ti 730°C), and Experimental Example 2-5 (Ti 800°C). p ) was calculated and presented in a graph. And, the I of the positive electrode active material according to Experimental Example 2-1 (Ti 725°C), Experimental Example 2-2 (Ti 730°C), and Experimental Example 2-5 (Ti 800°C) measured in (b) of Fig. 14 (003) / I (104) were presented together in a graph.

[0336] <Mathematical Formula 1>

[0337] χ -1 =(T-θ p ) / C p (χ = magnetization rate, T = temperature (K), θ p =Temperature constant, C p =Curie constant)

[0338] As can be seen in Fig. 40, the temperature constant of the positive electrode active material according to Experimental Example 2-1 is 28.1 K, and I (003) / I (104) It can be seen that is 0.88. The temperature constant of the positive electrode active material according to Experimental Example 2-2 is 25.5 K, and I (003) / I (104) It can be seen that is 1.04. The temperature constant of the positive electrode active material according to Experimental Example 2-5 is 24.2 K, and I (003) / I (104) It can be seen that is 1.15.

[0339] As the temperature constant of the cathode active material increases, the proportion of +2 ions of nickel metal mixed in the lithium layer of the cathode active material increases, and the I of the cathode active material (003) / I (104) The smaller this is, the lower the proportion of +2 ions of nickel metal mixed within the lithium layer of the cathode active material.

[0340] Accordingly, it can be seen that the proportion of +2 ions of nickel metal mixed in the lithium layer of the cathode active material is higher in the order of the cathode active material according to Experimental Example 2-1, the cathode active material according to Experimental Example 2-2, and the cathode active material according to Experimental Example 2-5.

[0341] And, as explained in (a) and (b) of Fig. 9, it can be seen that the initial capacity and capacity retention rate of the lithium-ion battery to which the positive electrode active material according to Experimental Example 2-2 is applied are optimized. Accordingly, it can be seen that the ratio of +2 ions of nickel metal mixed within the lithium layer of the positive electrode active material according to Experimental Example 2-2 is optimized.

[0342]

[0343] Figure 41 is a table for comparing the ICP analysis results of positive electrode active materials according to experimental examples of the present invention.

[0344] Referring to Fig. 41, the cathode active materials according to Experimental Example 1-2 (Nb), Experimental Example 2-2 (Ti), Experimental Example 3-2 (Zr), Experimental Example 4-2 (Hf), Experimental Example 5-3 (Ta), Experimental Example 6-5 (W), and Experimental Example 7-3 (Mo) were analyzed by ICP.

[0345] As can be seen in Fig. 41, the cathode active material according to the experimental examples can be seen to include lithium metal, nickel metal having a lower proportion than the lithium metal, manganese metal having a lower proportion than the nickel metal, and a dopant having a lower proportion than the manganese metal.

[0346]

[0347] While the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to the specific embodiments described above, and should be interpreted in accordance with the appended claims. Furthermore, those skilled in the art will appreciate that numerous modifications and variations are possible without departing from the scope of the present invention.

[0348] The cathode active material according to an embodiment of the present invention can be used in various devices such as lithium secondary batteries, electric vehicles, mobile devices, and ESS.

Claims

1. Step of preparing a positive electrode active material precursor; A step of setting the temperature within the heat treatment equipment to the target firing temperature; and A step of manufacturing a cathode active material by firing the cathode active material precursor, lithium salt, and dopant material at the target firing temperature using the above heat treatment equipment, Depending on the dopant material, the target firing temperature is controlled, A method for manufacturing a cathode active material, including controlling the initial capacity and capacity retention rate of a lithium secondary battery according to the above target firing temperature.

2. In paragraph 1, The above dopant material is Ti, and the target firing temperature is controlled to be greater than 725°C and less than 750°C, The above dopant material is Hf, and the target firing temperature is controlled to be greater than 725°C and less than 775°C, The above dopant material is Nb, and the target firing temperature is controlled to be greater than 725°C and less than 775°C, The above dopant material is Ta, and the target firing temperature is controlled to be greater than 750°C and less than 800°C, or The above dopant material is W, and the target firing temperature is controlled to be greater than 800°C and less than 900°C, The above dopant material is Mo, and the target firing temperature is controlled to be greater than 725°C and less than 750°C, Alternatively, a method for producing a cathode active material, wherein the dopant material is Zr and the target sintering temperature is controlled to be greater than 700°C and less than 750°C.

3. In paragraph 1, The step of preparing the above positive electrode active material precursor is: A method for producing a cathode active material, comprising a step of producing a transition metal hydroxide by a co-precipitation method using a transition metal precursor.

4. In paragraph 3, The above transition metal precursor does not contain cobalt, A method for producing a cathode active material, wherein the above transition metal precursor comprises a nickel precursor and a manganese precursor.

5. In paragraph 4, A method for producing a cathode active material, comprising controlling the ratio of the cathode active material precursor, the lithium salt, and the dopant material to be 1.03:1.00:0.

01.

6. In paragraph 5, The above nickel precursor is NiSO 4ㆍ Contains 6H2O, The above manganese precursor is MnSO 4ㆍ Contains 5H2O, The above lithium salt is LiOH ㆍ A method for producing a cathode active material containing H2O.

7. In a method for manufacturing a cathode active material, the method comprises heat-treating a preliminary cathode active material manufactured by mixing a cathode active material precursor, a lithium salt, and a dopant material, zirconium, at a target sintering temperature. A method for manufacturing a cathode active material, wherein, during a heat treatment process at the target sintering temperature, stress is applied to the (104) plane of the preliminary cathode active material, so that particles of the cathode active material grow from the (104) plane to the (003) plane.

8. In paragraph 7, Peak value I corresponding to the above (003) surface (003) And the peak value I corresponding to the above (104) surface (104) I is the ratio (003) / I (104 ) is controlled to be greater than 1.0 and less than 1.

1.

9. In paragraph 8, A method for manufacturing a cathode active material, wherein the dopant material comprises any one of Ti, Hf, Nb, Ta, W, Mo, or Zr.

10. In a cathode active material containing secondary particles formed by agglomeration of multiple primary particles, Among the surface and the inside of the above cathode active material, the surface contains more primary particles having a rod shape than the inside, The cathode active material comprises lithium metal, nickel metal in a smaller proportion than the lithium metal, manganese metal in a smaller proportion than the nickel metal, and a dopant in a smaller proportion than the manganese metal. The above dopant ratio includes the surface being higher than the interior, The above cathode active material includes a grain size of 40 nm or more and 60 nm or less, When analyzing the above cathode active material by XRD, the peak value I corresponding to the (003) plane (003) Peak value I corresponding to (104) surface (104) I is the ratio (003) / I (104) A cathode active material comprising a material having a value greater than 1.0 and less than 1.

1.

11. In a cathode active material containing secondary particles formed by agglomeration of multiple primary particles, Among the surface and the inside of the above cathode active material, the surface contains more primary particles having a rod shape than the inside, The cathode active material comprises lithium metal, nickel metal in a proportion smaller than the lithium metal, manganese metal in a proportion smaller than the nickel metal, and a dopant in a proportion smaller than the manganese metal. The ratio of the above dopant is such that the surface is higher than the interior, The above cathode active material includes a grain size of 40 nm or more and 60 nm or less, A cathode active material, wherein, when the cathode active material is subjected to XRD analysis, c / 3a, which is a ratio of the c-axis and the a-axis of the crystal lattice of the cathode active material, exceeds 1.6459.

12. In a cathode active material containing secondary particles formed by agglomeration of multiple primary particles, Among the surface and the inside of the above cathode active material, the surface contains more primary particles having a rod shape than the inside, The cathode active material comprises lithium metal, nickel metal in a proportion smaller than the lithium metal, manganese metal in a proportion smaller than the nickel metal, and a dopant in a proportion smaller than the manganese metal. The ratio of the above dopant is such that the surface is higher than the interior, The above cathode active material includes a grain size of 40 nm or more and 60 nm or less, The cathode active material comprises a transition metal layer including the nickel metal and the manganese metal alternately and repeatedly laminated and a lithium layer including the lithium metal, and a cathode active material comprising a superlattice in which +2 ions of the nickel metal are mixed within the lithium layer.

13. In paragraph 10, The above dopant comprises Ti, The ratio of +2 ions of the nickel metal mixed in the lithium layer is the temperature constant (θ) of the positive electrode active material. p ) increases, including the increasing, Temperature constant (θ) of the above cathode active material p ) is a cathode active material including one having a temperature exceeding 24.2K and less than 28.1K.

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