Lithium metal composite oxide powder, positive electrode active material for non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary batteries

Abstract

To provide a lithium metal composite oxide powder that exhibits superior cycle characteristics and lower electrical resistance when used as a positive electrode active material for a non-aqueous electrolyte secondary battery, and a positive electrode active material for a non-aqueous electrolyte secondary battery and a non-aqueous electrolyte secondary battery using the same. [Solution] The lithium-lithium metal composite oxide powder according to this disclosure comprises lithium metal composite oxide particles containing at least Li, Ni, Zr, and Ti. When the cross-section of the lithium metal composite oxide particles is analyzed using a two-dimensional high-resolution secondary ion mass spectrometer, the ratio of the maximum intensity of Zr near the surface of the lithium metal composite oxide particles to the average intensity of Zr near the center of the lithium metal composite oxide particles is 1.5 or more and 3.5 or less, and the ratio of the maximum intensity of Ti near the surface of the lithium metal composite oxide particles to the average intensity of Ti near the center of the lithium metal composite oxide particles is 0.60 or more and 2.6 or less.

Description

[Technical Field]

[0001] This disclosure relates to lithium metal composite oxide powder, positive electrode active material for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary batteries. [Background technology]

[0002] In recent years, the proliferation of portable, cordless electronic devices such as mobile phones and laptop computers has been rapid, and non-aqueous rechargeable batteries, which are small, lightweight, and have high energy density, are used as power sources for these devices. Among these, lithium-ion rechargeable batteries, which use materials such as lithium nickelate for the positive electrode and have the advantage of large charge and discharge capacity, are widely used.

[0003] As a positive electrode active material for lithium-ion secondary batteries, research has been actively conducted on layered rock salt oxide-based positive electrode active materials for lithium-ion secondary batteries (basic composition: Li(NiM)O2), which are solid solutions of nickel (Ni) and other transition metals M, offering excellent versatility.

[0004] Future cathode materials are expected to exhibit high battery voltages, similar to lithium-cobalt composite oxides, and have large charge / discharge capacities, expanding the range of applications for lithium-ion secondary batteries such as electric vehicles and stationary storage batteries. Further research and development are actively underway to achieve this.

[0005] However, lithium-ion secondary batteries are generally known to experience a gradual decrease in capacity with repeated charge / discharge cycles, and also to a reduction in capacity due to storage in a charged state at high temperatures. These issues are thought to be caused by changes in the crystal structure and expansion / contraction of the cathode material, which has a layered rock salt structure, due to repeated charge / discharge cycles and the state of charge.

[0006] To suppress the deterioration of battery characteristics due to repeated cycles and to improve cycle characteristics, for example, Patent Document 1 proposes a lithium metal composite oxide in which the basic composition is LiMO2 and M is a group of four or more elements including at least three elements selected from Co, Mn, Al, Mg, and Ti, and Ni. According to Patent Document 1, in such a lithium metal composite oxide, by substituting metal sites with Al and further substituting metal sites and Li sites with Mg, the expansion and contraction rate of the crystal structure due to the insertion and removal of Li during charging and discharging can be reduced, and as a result irreversible reactions can be mitigated, thereby improving cycle characteristics. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2011-023335 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the case of positive electrode active materials for non-aqueous electrolyte secondary batteries, as shown in Patent Document 1, the cycle characteristics are excellent as described above, but on the other hand, doping with different elements tends to lead to an increase in electrical resistance.

[0009] This disclosure has been made in view of the above circumstances, and aims to provide a lithium metal composite oxide powder that exhibits superior high-temperature storage characteristics and lower electrical resistance when used as a positive electrode active material for a non-aqueous electrolyte secondary battery, as well as a positive electrode active material for a non-aqueous electrolyte secondary battery and a non-aqueous electrolyte secondary battery using the same. [Means for solving the problem]

[0010] The inventors have diligently conducted research to solve the above-mentioned problems. As a result, they have found that a lithium metal composite oxide powder containing particles of a lithium metal composite oxide comprising at least Li, Ni, Zr, and Ti, wherein when the cross-section of the lithium metal composite oxide particles is analyzed using a two-dimensional high-resolution secondary ion mass spectrometer, the ratio of the maximum intensity of Zr near the surface of the lithium metal composite oxide particles to the average intensity of Zr near the center of the lithium metal composite oxide particles is 1.5 or more and 3.5 or less, and the ratio of the maximum intensity of Ti near the surface of the lithium metal composite oxide particles to the average intensity of Ti near the center of the lithium metal composite oxide particles is 0.60 or more and 2.6 or less, exhibits superior high-temperature storage characteristics and lower electrical resistance when used as a positive electrode active material for a non-aqueous electrolyte secondary battery. This disclosure provides the following.

[0011] (1) A lithium metal composite oxide powder comprising particles of a lithium metal composite oxide containing at least Li, Ni, Zr, and Ti, When the lithium metal composite oxide particles were analyzed cross-sectionally using a two-dimensional high-resolution secondary ion mass spectrometer, The ratio of the maximum Zr intensity near the surface of the lithium metal composite oxide particles to the average Zr intensity near the center of the lithium metal composite oxide particles is 1.5 or more and 3.5 or less. The ratio of the maximum Ti intensity near the surface of the lithium metal composite oxide particles to the average Ti intensity near the center of the lithium metal composite oxide particles is 0.60 or more and 2.6 or less. Lithium metal composite oxide powder.

[0012] (2) When the lithium metal composite oxide particles are analyzed in cross-section using a two-dimensional high-resolution secondary ion mass spectrometer, The coefficient of variation of the ratio of the average intensity of Zr near the center of the cross-section of the lithium metal composite oxide particles to the average intensity of Zr in the background is 0.10 or more and 1.4 or less. The lithium metal composite oxide powder described in (1) above.

[0013] (3) When a cross-section of the particles of the lithium metal composite oxide is analyzed using a two-dimensional high-resolution secondary ion mass spectrometer, the coefficient of variation of the ratio of the Ti intensity in the vicinity of the center of the particles of the lithium metal composite oxide to the average Ti intensity of the background is 0.10 or more and 1.5 or less The lithium metal composite oxide powder according to (1) or (2) above.

[0014] (4) The lithium metal composite oxide has a layered rock salt structure, General formula Li a Ni x Co y Mn z Zr u Ti v M w O α (wherein M is one or more elements other than Li, Ni, Co, Mn, Zr, Ti and O, 0.90≦a≦1.4, x+y+z+u+v+w=1.00, 0<u≦0.015, 0<v≦0.030, and 1.60≦α≦2.40) The lithium metal composite oxide powder according to (1) or (2) above.

[0015] (5) A positive electrode active material for a non-aqueous electrolyte secondary battery comprising the lithium metal composite oxide powder according to (1) or (2) above.

[0016] (6) A non-aqueous electrolyte secondary battery comprising the positive electrode active material for a non-aqueous electrolyte secondary battery according to (5) above. Effects of the Invention

[0017] According to the present disclosure, there can be provided a lithium metal composite oxide powder that exhibits more excellent high-temperature storage characteristics and lower electrical resistance when used as a positive electrode active material for a non-aqueous electrolyte secondary battery. Brief Description of Drawings

[0018] [Figure 1] This is a schematic diagram of the particles used to explain the maximum particle size of the particles selected for observation. [Figure 2] This is a schematic diagram of a particle used to explain the method for selecting the three lines used in the line profile of the particle selected for observation. [Figure 3] (a) A schematic diagram of the particles selected for observation, and (b) a diagram showing the correspondence between the line profile and the selected particles. [Figure 4] This is a schematic diagram of a line profile to explain the maximum intensity near the surface, near the center, and near the surface in a line profile. [Modes for carrying out the invention]

[0019] The embodiments of this disclosure (hereinafter referred to as "these embodiments") will be described below, but this disclosure is not limited in any way by the description of the embodiments and can be implemented with appropriate modifications.

[0020] Lithium metal composite oxide powder The lithium metal composite oxide powder according to this embodiment contains particles of a lithium metal composite oxide that includes at least Li, Ni, Zr, and Ti. When the cross-section of these lithium metal composite oxide particles is analyzed using a two-dimensional high-resolution secondary ion mass spectrometer, the ratio of the maximum intensity of Zr near the surface of the lithium metal composite oxide particles to the average intensity of Zr near the center of the lithium metal composite oxide particles is 1.5 or more and 3.5 or less, and the ratio of the maximum intensity of Ti near the surface of the lithium metal composite oxide particles to the average intensity of Ti near the center of the lithium metal composite oxide particles is 0.60 or more and 2.6 or less.

[0021] In such lithium metal composite oxide powders, the uniform distribution of Zr and Ti within the particles strengthens the crystalline structure through a synergistic effect. Specifically, the uniform distribution of Zr is thought to widen the gaps between layers in the layered structure, allowing a large amount of Ti, which has a relatively large ionic radius, to be substituted into the crystalline structure. This large substitution of Ti facilitates the formation of Li2MnO3, which exhibits particularly superior high-temperature storage characteristics when used as a positive electrode active material in non-aqueous electrolyte secondary batteries, including lithium-ion secondary batteries.

[0022] Furthermore, because the amount of Zr near the particle surface is greater than the amount of Zr near the particle center, Zr reacts with Li, forming a fine Li-Zr compound film. In addition, it is thought that some of the Ti that was not substituted inside the particle exists together with the Li-Zr compound as a Li-Ti compound, which synergistically improves the Li ion conductivity. As a result, it exhibits particularly superior low resistance.

[0023] As described above, by using the distribution of Zr and Ti in this embodiment, it is possible to obtain a lithium metal composite oxide powder that exhibits excellent high-temperature storage properties and excellent resistance.

[0024] When a cross-sectional analysis of lithium metal composite oxide particles is performed using a two-dimensional high-resolution secondary ion mass spectrometer, the ratio of the maximum Zr intensity near the surface of the lithium metal composite oxide particle to the average Zr intensity near the center of the lithium metal composite oxide particle (hereinafter sometimes referred to as the "Zr intensity ratio") is not particularly limited as long as it is between 1.5 and 3.5, but is preferably, for example, 1.6 or higher, 1.7 or higher, 1.8 or higher, 1.9 or higher, 2.0 or higher, 2.1 or higher, 2.2 or higher, 2.3 or higher, or 2.4 or higher. On the other hand, the Zr intensity ratio is preferably 3.4 or lower, 3.3 or lower, 3.2 or lower, 3.1 or lower, 3.0 or lower, 2.9 or lower, 2.8 or lower, 2.7 or lower, or 2.6 or lower.

[0025] When a cross-sectional analysis of lithium metal composite oxide particles is performed using a two-dimensional high-resolution secondary ion mass spectrometer, the coefficient of variation of the ratio of the average Zr intensity near the center of the cross-section of the lithium metal composite oxide particles to the average Zr intensity of the background (hereinafter sometimes referred to as the "coefficient of variation of Zr intensity") is not particularly limited, but is preferably, for example, 0.10 or higher, 0.12 or higher, 0.15 or higher, 0.17 or higher, 0.20 or higher, 0.22 or higher, 0.25 or higher, 0.27 or higher, or 0.30 or higher. On the other hand, the coefficient of variation of Zr intensity is preferably 1.4 or lower, 1.3 or lower, 1.2 or lower, 1.0 or lower, 0.90 or lower, 0.80 or lower, 0.70 or lower, 0.60 or lower, 0.50 or lower, 0.40 or lower, or 0.30 or lower.

[0026] When a cross-sectional analysis of lithium metal composite oxide particles is performed using a two-dimensional high-resolution secondary ion mass spectrometer, the ratio of the maximum Ti intensity near the surface of the lithium metal composite oxide particle to the average Ti intensity near the center of the lithium metal composite oxide particle (hereinafter sometimes referred to as the "Ti intensity ratio") is not particularly limited as long as it is between 0.60 and 2.6, but is preferably, for example, 0.70 or higher, 0.80 or higher, 0.90 or higher, 1.0 or higher, 1.1 or higher, or 1.2 or higher. On the other hand, the Ti intensity ratio is preferably 2.5 or lower, 2.4 or lower, 2.3 or lower, 2.2 or lower, 2.1 or lower, 2.0 or lower, 1.9 or lower, 1.8 or lower, or 1.7 or lower.

[0027] When a cross-sectional analysis of lithium metal composite oxide particles is performed using a two-dimensional high-resolution secondary ion mass spectrometer, the coefficient of variation of the ratio of the Ti intensity near the center of the lithium metal composite oxide particle to the average background Ti intensity (hereinafter sometimes referred to as the "coefficient of variation of Ti intensity") is not particularly limited, but is preferably, for example, 0.10 or higher, 0.12 or higher, 0.15 or higher, 0.17 or higher, 0.20 or higher, 0.22 or higher, 0.25 or higher, or 0.27 or higher. On the other hand, the coefficient of variation of Ti intensity is preferably 1.5 or lower, 1.4 or lower, 1.3 or lower, 1.2 or lower, 1.0 or lower, 0.90 or lower, 0.80 or lower, 0.70 or lower, 0.60 or lower, 0.50 or lower, 0.40 or lower, or 0.35 or lower.

[0028] [Line analysis using a two-dimensional high-resolution secondary ion mass spectrometer] The following describes a specific method for line analysis of the cross-section of lithium metal composite oxide particles using a two-dimensional high-resolution secondary ion mass spectrometer.

[0029] Line analysis is performed using a two-dimensional high-resolution secondary ion mass spectrometer (NanoSIMS 50L, CAMECA) to obtain information about the particle surface and interior. Specifically, oxygen is used as the primary ion species, and the primary ion acceleration voltage is set to 16kV, and the analysis is performed based on the detected secondary ions.

[0030] The observed lithium metal composite oxide powder sample is fixed with resin, cross-sectionally processed using the BIB method, and charge compensation is performed by metal coating the processed surface. Except for the metal coating process, all sampling-related operations are performed in an inert atmosphere. After that, the sample is placed on the sample stage, and the outermost surface is cleaned with an ion beam immediately before observation.

[0031] Prior to observation using a two-dimensional high-resolution secondary ion mass spectrometer, SEM observation is performed to select particles from the lithium metal composite oxide powder sample whose particle size is 0.95 to 1.05 times the average particle size (D50) as the observation target. At this time, the coordinates of the secondary particles to be observed are recorded, and these coordinates are used as a reference during observation with the two-dimensional high-resolution secondary ion mass spectrometer. Note that the lithium metal composite oxide particles may be in the form of primary particles or secondary particles formed by the aggregation of multiple primary particles. If the particles are in the form of secondary particles, line analysis is performed on the entire secondary particle as a single particle, rather than performing line analysis on the primary particles contained within it, as shown below.

[0032] Furthermore, D50 is measured using a wet laser method based on volume using a laser particle size distribution analyzer (Microtrac HRA, manufactured by Nikkiso Co., Ltd.).

[0033] The following explains the method for selecting lines to be used in the line profile, using Figures 1 and 2. Figure 1 is a schematic diagram of a particle used to explain the maximum particle diameter of the particle selected for observation. Figure 2 is a schematic diagram of a particle used to explain the method for selecting the three lines to be used in the line profile of the particle selected for observation.

[0034] The lines used for line profiling are selected such that the lengths L2 to L4 from end to end are 1.5 times the length of the line segment L1 (the longest line connecting two points on the particle's contour, see Figure 1) that represents the maximum particle diameter Dmax of the selected particle P. Three lines are selected that form a 60° angle to each other, with at least 0.6 times the length of each line passing through the interior of particle P. All three lines L2 to L4 are selected so that 0.6 times their length (only S1 for L2 is shown in the figure) passes through the interior of particle P (see Figure 2). If it is not possible to select at least one of the three lines so that 0.6 times their length passes through the interior of the particle, that particle is excluded from line analysis, and another particle is selected. In Figures 1 and 2, the line segment L1 representing the maximum particle diameter Dmax of the observed particle P and one of the three selected lines, line L4, are assumed to be on the same line. However, the line segment representing the maximum particle diameter Dmax of the observed particle and one of the three selected lines do not necessarily have to be on the same line.

[0035] The line profile spacing is set to 80 nm for Ti and 500 nm for Zr. The line profile is smoothed by taking a moving average of the intensity of five points: the center point of the numerical value and two points before and after it, and this is used for analysis.

[0036] The definitions of the vicinity of the surface and the vicinity of the center of particle P, which was selected as the object of observation, will be explained below using Figures 3 and 4. Figure 3 shows (a) a schematic diagram of the particle selected as the object of observation and (b) the correspondence with the line profile. Figure 4 is a schematic diagram of the line profile to explain the vicinity of the surface, the vicinity of the center, and the maximum intensity near the surface.

[0037] (Near surface and maximum strength) For each of the three lines, in the line profile, a range between points P1 and P3 where the count number exceeds 10 times that of the background and points P2 and P4 obtained by advancing a distance of 0.3 times the maximum particle diameter Dmax of the target particle from the respective points into the inside of the particle is defined as the vicinity of the surface (see FIG. 4). The maximum count numbers for Zr and Ti within this range are determined (see FIG. 4). The vicinity of the surface is present at both ends of the particle as shown in FIG. 4, and the maximum intensity is determined as the maximum count number among all ranges in the vicinity of the surface at both ends. Thereafter, the arithmetic average of the maximum count numbers for each of the three lines is taken as the maximum intensity.

[0038] (Near Center and Average Intensity) For each of the three lines, a range inside of the vicinity of the surface at both ends of the particle is defined as the near center (see FIG. 4). The arithmetic average of the count numbers of Zr and Ti within this range is determined for each of the three lines. Thereafter, the arithmetic average of the arithmetic averages of the count numbers for each of the three lines is calculated, and this is taken as the average intensity.

[0039] (Background and Average Intensity) For each of the three lines, a location where no particle is present in the cross-sectional SEM image, which is not a portion close to the vicinity of the surface where the line profile rises, is defined as the background. Count numbers of Zr and Ti are measured for a total of 60 points, 20 background points randomly selected from each of the three lines, and the arithmetic average of these count numbers is taken as the average intensity.

[0040] The chemical composition of the lithium metal composite oxide is not particularly limited, and has a layered rock salt structure represented by the general formula Li a Ni x Co y Mn z Zr u Ti v M w O α(wherein M is one or more elements other than Li, Ni, Co, Mn, Zr, Ti and O, 0.90≦a≦1.4, x+y+z+u+v+w=1.00, 0<u≦0.015, 0<v≦0.030, 1.60≦α≦2.40) is preferably used.

[0041] In the general formula for lithium metal composite oxides, the value of a is not particularly limited as long as it is within the range of 0.90 ≤ a ≤ 1.4, but for example, 0.905 or more, 0.91 or more, 0.915 or more, 0.92 or more, 0.925 or more, 0.93 or more, 0.935 or more, 0.94 or more, 0.945 or more, 0.95 or more, 0.955 or more, 0.96 or more, 0.965 or more, 0.97 or more, 0.975 or more, 0.98 or more, 0.985 or more, 0.99 or more, 0.995 or more, 1 or higher, 1.005 or higher, 1.01 or higher, 1.015 or higher, 1.02 or higher, 1.025 or higher, 1.03 or higher, 1.035 or higher, 1.04 or higher, 1.045 or higher, 1.05 or higher, 1.06 or higher, 1.065 or higher, 1.07 or higher, 1.075 or higher, 1.08 or higher, 1.085 or higher, 1.09 or higher, 1.095 or higher, 1.1 or higher, 1.105 or higher, 1.11 or higher, 1.115 or higher, 1.12 or higher, 1.125 or higher, 1.13 or higher, 1. 135 or higher, 1.14 or higher, 1.145 or higher, 1.15 or higher, 1.155 or higher, 1.16 or higher, 1.165 or higher, 1.17 or higher, 1.175 or higher, 1.18 or higher, 1.185 or higher, 1.19 or higher, 1.195 or higher, 1.2 or higher, 1.205 or higher, 1.21 or higher, 1.215 or higher, 1.22 or higher, 1.225 or higher, 1.23 or higher, 1.235 or higher, 1.24 or higher, 1.245 or higher, 1.25 or higher, 1.255 or higher, 1.26 or higher, 1.265 or higher, It may be 1.27 or higher, 1.275 or higher, 1.28 or higher, 1.285 or higher, 1.29 or higher, 1.295 or higher, 1.3 or higher, 1.105 or higher, 1.11 or higher, 1.115 or higher, 1.12 or higher, 1.125 or higher, 1.13 or higher, 1.135 or higher, 1.14 or higher, 1.145 or higher, 1.15 or higher, 1.155 or higher, 1.16 or higher, 1.165 or higher, 1.17 or higher, 1.175 or higher, 1.18 or higher, 1.185 or higher, 1.19 or higher, or 1.195 or higher.On the other hand, the value of a may be 1.395 or less, 1.39 or less, 1.385 or less, 1.38 or less, 1.375 or less, 1.37 or less, 1.365 or less, 1.36 or less, 1.355 or less, 1.35 or less, 1.345 or less, 1.34 or less, 1.335 or less, 1.33 or less, 1.325 or less, 1.32 or less, 1.315 or less, 1.31 or less, 1.305 or less, 1.3 or less, 1.3 or less, 1.295 or less, 1.29 or less, 1.285 or less, 1.28 or less, 1.275 or less, 1.27 or less, 1.265 or less, 1.26 or less, 1.255 or less, 1.25 or less, 1.245 or less, 1.24 or less, 1.235 or less, 1.23 or less, 1.225 or less, 1.22 or less, 1.215 or less, 1.21 or less, 1.205 or less, 1.2 or less, 1.195 or less, 1.19 or less, 1.185 or less, 1.18 or less, 1.175 or less, 1.17 or less, 1.165 or less, 1.16 or less, 1.155 or less, 1.15 or less, 1.145 or less, 1.14 or less, 1.135 or less, 1.13 or less, 1.125 or less, 1.12 or less, 1.115 or less, 1.11 or less, 1.105 or less, 1.1 or less, 1.095 or less, 1.09 or less, 1.085 or less, 1.08 or less, 1.075 or less, 1.07 or less, 1.065 or less, 1.06 or less, 1.055 or less, 1.05 or less, 1.045 or less, 1.04 or less, 1.035 or less, 1.03 or less, 1.025 or less, 1.02 or less, 1.015 or less, 1.01 or less, 1.005 or less, 1 or less, 0.995 or less, 0.99 or less, 0.985 or less, 0.98 or less, 0.975 or less, 0.97 or less, 0.965 or less, 0.96 or less, 0.955 or less, 0.95 or less, 0.945 or less, 0.94 or less, 0.935 or less, 0.93 or less, 0.925 or less, 0.92 or less, 0.915 or less, 0.91 or less, 0.905 or less, or 0.90 or less.

[0042] In the general formula for lithium metal composite oxide, the value of x is not particularly limited, but for example, it can be 0 or greater, greater than 0, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.005 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0.0075 or greater, 0.008 or greater, 0.0085 or greater, 0.009 or greater, 0.0095 or greater, 0.01 or greater, 0.015 or greater, 0.02 or greater, 0.025 or greater, 0.03 or greater, 0.035 or greater, 0.04 or greater. , 0.045 or higher, 0.05 or higher, 0.055 or higher, 0.06 or higher, 0.065 or higher, 0.07 or higher, 0.075 or higher, 0.08 or higher, 0.085 or higher, 0.09 or higher, 0.095 or higher, 0.1 or higher, 0.105 or higher, 0.11 or higher, 0.115 or higher, 0.12 or higher, 0.125 or higher, 0.13 or higher, 0.135 or higher, 0.14 or higher, 0.145 or higher, 0.15 or higher, 0.155 or higher, 0.16 or higher, 0.165 or higher, 0.17 or higher, 0.175 or higher, 0.18 or higher, 0.185 or higher, 0.19 or higher, 0.195 or higher, 0.2 or higher, 0.205 or higher, 0. 21 or higher, 0.215 or higher, 0.22 or higher, 0.225 or higher, 0.23 or higher, 0.235 or higher, 0.24 or higher, 0.245 or higher, 0.25 or higher, 0.255 or higher, 0.26 or higher, 0.265 or higher, 0.27 or higher, 0.275 or higher, 0.28 or higher, 0.285 or higher, 0.29 or higher, 0.295 or higher, 0.3 or higher, 0.305 or higher, 0.31 or higher, 0.315 or higher, 0.32 or higher, 0.325 or higher, 0.33 or higher, 0.335 or higher, 0.34 or higher, 0.355 or higher, 0.36 or higher, 0.365 or higher, 0.37 or higher, 0.375 Above, 0.38 or above, 0.385 or above, 0.39 or above, 0.395 or above, 0.4 or above, 0.405 or above, 0.41 or above, 0.415 or above, 0.42 or above, 0.425 or above, 0.43 or above, 0.435 or above, 0.44 or above, 0.445 or above, 0.45 or above, 0.46 or above, 0.465 or above, 0.47 or above, 0.475 or above, 0.48 or above, 0.485 or above, 0.49 or above, 0.495 or above, 0.5 or above, 0.505 or above, 0.51 or above, 0.515 or above, 0.52 or above, 0.525 or above, 0.53 or above, 0.535 or above, 0.54 or above, 0.545 or higher, 0.55 or higher, 0.555 or higher, 0.56 or higher, 0.565 or higher, 0.57 or higher, 0.575 or higher, 0.58 or higher, 0.585 or higher, 0.59 or higher, 0.595 or higher, 0.6 or higher, 0.605 or higher, 0.61 or higher, 0.615 or higher, 0.62 or higher, 0.625 or higher, 0.63 or higher, 0.635 or higher, 0.64 or higher, 0.645 or higher, 0.65 or higher, 0.655 or higher, 0.66 or higher, 0.665 or higher, 0.67 or higher, 0.675 or higher, 0.68 or higher, 0.685 or higher, 0.69 or higher, 0.695 or higher, 0.7 or higher, 0.705 or higher, 0.71 or higher, 0.715 or higher, 0.72 or higher, 0.725 or higher, 0.73 or higher, 0.735 or higher, 0.74 or higher, 0.745 or higher, 0.75 or higher, 0.755 or higher, 0.76 or higher, 0.765 or higher, 0.77 or higher, 0.775 or higher, 0.78 or higher, 0.785 or higher, 0.79 or higher, 0.795 or higher, 0.8 or higher, 0.805 or higher, 0.81 or higher, 0.815 or higher, 0.82 or higher, 0.825 or higher, 0.83 or higher, 0.835 or higher, 0.84 or higher, 0.845 or higher, 0.85 or higher, 0.855 or higher, 0.86 or higher, 0.865 or higher, 0.87 or higher, 0.875 or higher, 0.88 or higher, 0.885 or higher It may be 0.89 or higher, 0.895 or higher, 0.9 or higher, 0.905 or higher, 0.91 or higher, 0.915 or higher, 0.92 or higher, 0.925 or higher, 0.93 or higher, 0.935 or higher, 0.94 or higher, 0.945 or higher, 0.95 or higher, 0.955 or higher, 0.96 or higher, 0.965 or higher, 0.97 or higher, 0.975 or higher, 0.98 or higher, 0.985 or higher, 0.99 or higher, or 0.995 or higher. On the other hand, the values ​​of x are 1 or less, 0.997 or less, 0.995 or less, 0.992 or less, 0.99 or less, 0.987 or less, 0.985 or less, 0.982 or less, 0.98 or less, 0.977 or less, 0.975 or less, 0.972 or less, 0.97 or less, 0.967 or less, 0.965 or less, 0.962 or less, 0.96 or less, 0.957 or less, 0.955 or less, 0 .952 or less, 0.95 or less, 0.947 or less, 0.945 or less, 0.942 or less, 0.94 or less, 0.937 or less, 0.935 or less, 0.932 or less, 0.93 or less, 0. 927 or less, 0.925 or less, 0.922 or less, 0.92 or less, 0.917 or less, 0.915 or less, 0.912 or less, 0.91 or less, 0.907 or less, 0.905 or less, 0.It can be 902 or less, or 0.9 or less.

[0043] In the general formula for lithium metal composite oxide, the value of y is not particularly limited, but for example, it can be 0 or greater, greater than 0, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.005 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0.0075 or greater, 0.008 or greater, 0.0085 or greater, 0.009 or greater, 0.0095 or greater, 0.01 or greater, 0.015 or greater, 0.02 or greater, 0.025 or greater, 0.03 or greater, 0.035 or greater, 0.04 or greater. , 0.045 or higher, 0.05 or higher, 0.055 or higher, 0.06 or higher, 0.065 or higher, 0.07 or higher, 0.075 or higher, 0.08 or higher, 0.085 or higher, 0.09 or higher, 0.095 or higher, 0.1 or higher, 0.102 or higher, 0.105 or higher, 0.107 or higher, 0.11 or higher, 0.112 or higher, 0.115 or higher, 0.117 or higher, 0.12 or higher, 0.122 or higher, 0.125 or higher, 0.127 or higher, 0.13 or higher, 0.132 or higher, 0.135 or higher, 0.137 or higher, 0.14 or higher, 0.142 or higher, 0.145 or higher, 0.147 or higher, 0.15 or higher, 0.152 Above, 0.155 or above, 0.157 or above, 0.16 or above, 0.162 or above, 0.165 or above, 0.167 or above, 0.17 or above, 0.172 or above, 0.175 or above, 0.177 or above, 0.18 or above, 0.182 or above, 0.185 or above, 0.187 or above, 0.19 or above, 0.192 or above, 0.195 or above, 0.197 or above, 0.2 or above, 0.202 or above, 0.205 or above, 0.207 or above, 0.21 or above, 0.212 or above, 0.215 or above, 0.217 or above, 0.222 or above, 0.225 or above, 0.227 or above, 0.23 or above, 0.232 or above , 0.235 or higher, 0.237 or higher, 0.24 or higher, 0.242 or higher, 0.245 or higher, 0.247 or higher, 0.25 or higher, 0.252 or higher, 0.255 or higher, 0.257 or higher, 0.26 or higher, 0.262 or higher, 0.265 or higher, 0.267 or higher, 0.27 or higher, 0.272 or higher, 0.275 or higher, 0.277 or higher, 0.28 or higher, 0.282 or higher, 0.285 or higher, 0.287 or higher, 0.29 or higher, 0.292 or higher, 0.295 or higher, 0.297 or higher, 0.3 or higher, 0.302 or higher, 0.305 or higher, 0.307 or higher, 0.31 or higher, 0.312 or higher, 0.It may be 315 or higher, 0.317 or higher, 0.32 or higher, 0.322 or higher, 0.325 or higher, 0.327 or higher, 0.33 or higher, 0.332 or higher, 0.335 or higher, 0.337 or higher, 0.34 or higher, 0.342 or higher, 0.345 or higher, 0.347 or higher, 0.352 or higher, 0.355 or higher, 0.357 or higher, 0.36 or higher, 0.362 or higher, 0.365 or higher, 0.367 or higher, 0.372 or higher, 0.375 or higher, 0.377 or higher, 0.38 or higher, 0.382 or higher, 0.385 or higher, 0.387 or higher, 0.39 or higher, 0.392 or higher, 0.395 or higher, or 0.397 or higher. On the other hand, the values ​​of y are 0.4 or less, 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.37 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less, 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0. 345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less, 0.272 or less, 0.27 or less, 0.267 or less, 0.265 or less, 0.26 or less, 0.257 or less, 0.255 or less Lower, 0.252 or less, 0.25 or less, 0.247 or less, 0.245 or less, 0.242 or less, 0.24 or less, 0.237 or less, 0.235 or less, 0.232 or less, 0.23 or less, 0.227 or less, 0.22 5 or less, 0.222 or less, 0.22 or less, 0.217 or less, 0.215 or less, 0.212 or less, 0.21 or less, 0.207 or less, 0.205 or less, 0.202 or less, 0.2 or less, 0.197 or less, 0.1 95 or less, 0.192 or less, 0.19 or less, 0.187 or less, 0.185 or less, 0.182 or less, 0.18 or less, 0.177 or less, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less, 0.127 or less, 0.125 or less, 0 .122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.0 It may be 65 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less, 0.008 or less, 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, 0.0015 or less, or 0.001 or less.

[0044] In the general formula for lithium metal composite oxides, the value of z is not particularly limited, but for example, it can be 0 or greater, greater than 0, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.005 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0.0075 or greater, 0.008 or greater, 0.0085 or greater, 0.009 or greater, 0.0095 or greater, 0.01 or greater, 0.015 or greater, 0.02 or greater, 0.025 or greater, 0.03 or greater, 0.035 or greater, 0.04 or greater. , 0.045 or higher, 0.05 or higher, 0.055 or higher, 0.06 or higher, 0.065 or higher, 0.07 or higher, 0.075 or higher, 0.08 or higher, 0.085 or higher, 0.09 or higher, 0.095 or higher, 0.1 or higher, 0.102 or higher, 0.105 or higher, 0.107 or higher, 0.11 or higher, 0.112 or higher, 0.115 or higher, 0.117 or higher, 0.12 or higher, 0.122 or higher, 0.125 or higher, 0.127 or higher, 0.13 or higher, 0.132 or higher, 0.135 or higher, 0.137 or higher, 0.14 or higher, 0.142 or higher, 0.145 or higher, 0.147 or higher, 0.15 or higher, 0.152 Above, 0.155 or above, 0.157 or above, 0.16 or above, 0.162 or above, 0.165 or above, 0.167 or above, 0.17 or above, 0.172 or above, 0.175 or above, 0.177 or above, 0.18 or above, 0.182 or above, 0.185 or above, 0.187 or above, 0.19 or above, 0.192 or above, 0.195 or above, 0.197 or above, 0.2 or above, 0.202 or above, 0.205 or above, 0.207 or above, 0.21 or above, 0.212 or above, 0.215 or above, 0.217 or above, 0.222 or above, 0.225 or above, 0.227 or above, 0.23 or above, 0.232 or above , 0.235 or higher, 0.237 or higher, 0.24 or higher, 0.242 or higher, 0.245 or higher, 0.247 or higher, 0.25 or higher, 0.252 or higher, 0.255 or higher, 0.257 or higher, 0.26 or higher, 0.262 or higher, 0.265 or higher, 0.267 or higher, 0.27 or higher, 0.272 or higher, 0.275 or higher, 0.277 or higher, 0.28 or higher, 0.282 or higher, 0.285 or higher, 0.287 or higher, 0.29 or higher, 0.292 or higher, 0.295 or higher, 0.297 or higher, 0.3 or higher, 0.302 or higher, 0.305 or higher, 0.307 or higher, 0.31 or higher, 0.312 or higher, 0.It may be 315 or higher, 0.317 or higher, 0.32 or higher, 0.322 or higher, 0.325 or higher, 0.327 or higher, 0.33 or higher, 0.332 or higher, 0.335 or higher, 0.337 or higher, 0.34 or higher, 0.342 or higher, 0.345 or higher, 0.347 or higher, 0.352 or higher, 0.355 or higher, 0.357 or higher, 0.36 or higher, 0.362 or higher, 0.365 or higher, 0.367 or higher, 0.372 or higher, 0.375 or higher, 0.377 or higher, 0.38 or higher, 0.382 or higher, 0.385 or higher, 0.387 or higher, 0.39 or higher, 0.392 or higher, 0.395 or higher, or 0.397 or higher. On the other hand, the values ​​of z are 0.4 or less, 0.397 or less, 0.395 or less, 0.392 or less, 0.39 or less, 0.387 or less, 0.385 or less, 0.382 or less, 0.38 or less, 0.377 or less, 0.375 or less, 0.372 or less, 0.37 or less, 0.367 or less, 0.365 or less, 0.362 or less, 0.36 or less, 0.357 or less, 0.355 or less, 0.352 or less, 0.35 or less, 0.347 or less, 0. 345 or less, 0.342 or less, 0.34 or less, 0.337 or less, 0.335 or less, 0.332 or less, 0.33 or less, 0.327 or less, 0.325 or less, 0.322 or less, 0.32 or less, 0.317 or less, 0.315 or less, 0.312 or less, 0.31 or less, 0.307 or less, 0.305 or less, 0.302 or less, 0.3 or less, 0.297 or less, 0.295 or less, 0.292 or less, 0.29 or less, 0.287 or less, 0.285 or less, 0.282 or less, 0.28 or less, 0.277 or less, 0.275 or less, 0.272 or less, 0.27 or less, 0.267 or less, 0.265 or less, 0.26 or less, 0.257 or less, 0.255 or less Lower, 0.252 or less, 0.25 or less, 0.247 or less, 0.245 or less, 0.242 or less, 0.24 or less, 0.237 or less, 0.235 or less, 0.232 or less, 0.23 or less, 0.227 or less, 0.22 5 or less, 0.222 or less, 0.22 or less, 0.217 or less, 0.215 or less, 0.212 or less, 0.21 or less, 0.207 or less, 0.205 or less, 0.202 or less, 0.2 or less, 0.197 or less, 0.1 95 or less, 0.192 or less, 0.19 or less, 0.187 or less, 0.185 or less, 0.182 or less, 0.18 or less, 0.177 or less, 0.175 or less, 0.172 or less, 0.17 or less, 0.167 or less, 0.165 or less, 0.162 or less, 0.16 or less, 0.155 or less, 0.152 or less, 0.15 or less, 0.147 or less, 0.145 or less, 0.142 or less, 0.14 or less, 0.137 or less, 0.135 or less, 0.132 or less, 0.13 or less, 0.127 or less, 0.125 or less, 0 .122 or less, 0.12 or less, 0.117 or less, 0.115 or less, 0.112 or less, 0.11 or less, 0.107 or less, 0.105 or less, 0.102 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.0 It may be 65 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less, 0.008 or less, 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, 0.0015 or less, or 0.001 or less.

[0045] In the general formula for lithium metal composite oxide, the value of u is not particularly limited, but may be greater than 0, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.005 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0.0075 or greater, 0.008 or greater, 0.0085 or greater, 0.009 or greater, or 0.0095 or greater. On the other hand, the value of u may be 0.015 or less, 0.014 or less, 0.013 or less, 0.012 or less, 0.011 or less, 0.01 or less, 0.0095 or less, 0.009 or less, 0.0085 or less, 0.008 or less, 0.0075 or less, 0.007 or less, 0.0065 or less, 0.006 or less, 0.0055 or less, 0.005 or less, 0.0045 or less, 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, 0.002 or less, or 0.0015 or less.

[0046] In the general formula for lithium metal composite oxides, the value of v is not particularly limited, but is generally greater than 0, 0.0005 or greater, 0.0006 or greater, 0.0007 or greater, 0.0008 or greater, 0.0009 or greater, 0.001 or greater, 0.0015 or greater, 0.002 or greater, 0.0025 or greater, 0.003 or greater, 0.0035 or greater, 0.004 or greater, 0.0045 or greater, 0.0055 or greater, 0.006 or greater, 0.0065 or greater, 0.007 or greater, 0.0075 or greater, 0.008 or greater, 0.0085 or greater, and 0.009 or greater. It may be 0.0095 or higher, 0.01 or higher, 0.0105 or higher, 0.011 or higher, 0.0115 or higher, 0.012 or higher, 0.0125 or higher, 0.013 or higher, 0.014 or higher, 0.0145 or higher, 0.015 or higher, 0.0155 or higher, 0.016 or higher, 0.0165 or higher, 0.017 or higher, 0.0175 or higher, 0.018 or higher, 0.0185 or higher, 0.019 or higher, 0.0195 or higher, 0.02 or higher, 0.0205 or higher, 0.021 or higher, 0.0215 or higher, 0.022 or higher, or 0.0225 or higher. On the other hand, the values ​​of u are 0.030 or less, 0.0295 or less, 0.029 or less, 0.0285 or less, 0.028 or less, 0.0275 or less, 0.027 or less, 0.0265 or less, 0.026 or less, 0.0255 or less, 0.025 or less, 0.0245 or less, 0.024 or less, 0.0235 0.023 or less, 0.0225 or less, 0.022 or less, 0.0215 or less, 0.021 or less, 0.0205 or less, 0.02 or less, 0.0195 or less, 0.019 or less, 0.0185 or less, 0.018 or less, 0.0175 or less, 0.017 or less, 0.0165 or less, 0.016 or less The following values ​​may be less than or equal to 0.0155, less than or equal to 0.015, less than or equal to 0.0145, less than or equal to 0.014, less than or equal to 0.0135, less than or equal to 0.013, less than or equal to 0.0125, less than or equal to 0.012, less than or equal to 0.0115, less than or equal to 0.011, less than or equal to 0.0105, less than or equal to 0.01, less than or equal to 0.0095, less than or equal to 0.009, less than or equal to 0.0085, less than or equal to 0.008, less than or equal to 0.0075, less than or equal to 0.007, less than or equal to 0.0065, less than or equal to 0.006, less than or equal to 0.0055, less than or equal to 0.005, less than or equal to 0.0045, less than or equal to 0.004, less than or equal to 0.0035, less than or equal to 0.003, less than or equal to 0.0025, less than or equal to 0.002, and less than or equal to 0.0015.

[0047] In the general formula for lithium metal composite oxide, the value of w is not particularly limited, but for example, it can be 0 or greater, greater than 0, 0.001 or greater, 0.0012 or greater, 0.0015 or greater, 0.0017 or greater, 0.0022 or greater, 0.0025 or greater, 0.0027 or greater, 0.003 or greater, 0.0032 or greater, 0.0035 or greater, 0.0037 or greater, 0.004 or greater, or 0.0 0.42 or higher, 0.0045 or higher, 0.0047 or higher, 0.005 or higher, 0.0052 or higher, 0.0055 or higher, 0.0057 or higher, 0.0062 or higher, 0.0065 or higher, 0.0067 or higher, 0.007 or higher, 0.0072 or higher, 0.0075 or higher, 0.0077 or higher, 0.0082 or higher, 0.0085 or higher, 0.0087 Above, 0.009 or above, 0.0092 or above, 0.0095 or above, 0.0097 or above, 0.01 or above, 0.012 or above, 0.015 or above, 0.017 or above, 0.02 or above, 0.022 or above, 0.025 or above, 0.027 or above, 0.03 or above, 0.032 or above, 0.035 or above, 0.037 or above, 0.04 or above, 0.042 or above, 0.045 or above, 0.047 or above , may be 0.05 or higher, 0.052 or higher, 0.055 or higher, 0.057 or higher, 0.06 or higher, 0.062 or higher, 0.065 or higher, 0.067 or higher, 0.07 or higher, 0.072 or higher, 0.075 or higher, 0.077 or higher, 0.08 or higher, 0.082 or higher, 0.085 or higher, 0.087 or higher, 0.09 or higher, 0.092 or higher, 0.095 or higher, or 0.097 or higher.On the other hand, the values ​​of w are 0.1 or less, 0.097 or less, 0.095 or less, 0.092 or less, 0.09 or less, 0.087 or less, 0.085 or less, 0.082 or less, 0.08 or less, 0.077 or less, 0.075 or less, 0.072 or less, 0.07 or less, 0.067 or less, 0.065 or less, 0.062 or less, 0.06 or less, 0.057 or less, and 0.055. Less than or equal to 0.052, less than or equal to 0.05, less than or equal to 0.047, less than or equal to 0.045, less than or equal to 0.042, less than or equal to 0.04, less than or equal to 0.037, less than or equal to 0.035, less than or equal to 0.032, 0.03 Less than or equal to 0.027, less than or equal to 0.025, less than or equal to 0.022, less than or equal to 0.02, less than or equal to 0.017, less than or equal to 0.015, less than or equal to 0.012, less than or equal to 0.01, less than or equal to 0.0097, 0.0 095 or less, 0.0092 or less, 0.009 or less, 0.0087 or less, 0.0085 or less, 0.0082 or less, 0.008 or less, 0.0077 or less, 0.0075 or less, 0 .0072 or less, 0.007 or less, 0.0067 or less, 0.0065 or less, 0.0062 or less, 0.006 or less, 0.0057 or less, 0.0055 or less, 0.0052 or less It may be 0.005 or less, 0.0047 or less, 0.0045 or less, 0.0042 or less, 0.004 or less, 0.0037 or less, 0.0035 or less, 0.0032 or less, 0.003 or less, 0.0027 or less, 0.0025 or less, 0.0022 or less, 0.002 or less, 0.0017 or less, 0.0015 or less, 0.0012 or less, or 0.001 or less.

[0048] In the general formula, element M is not particularly limited as long as it is one or more elements other than Li, Ni, Co, Mn, Zr, Ti, and O. For example, Al, Mg, Zn, Nb, W, Mo, Sb, V, Cr, Ca, Fe, Ga, Sr, Y, Ru, In, Sn, Ta, Bi, B, etc., can be used. The type of element M should be selected according to the purpose of addition. Also, if element M contains multiple elements, the value of w represents the total amount of the multiple elements.

[0049] In the general formula for lithium metal composite oxides, the value of α is not particularly limited, but for example, 1.61 or higher, 1.62 or higher, 1.63 or higher, 1.64 or higher, 1.65 or higher, 1.66 or higher, 1.67 or higher, 1.68 or higher, 1.69 or higher, 1.70 or higher, 1.71 or higher, 1.72 or higher, 1.73 or higher, 1.74 or higher, 1.75 or higher, 1.76 or higher, 1.77 or higher, 1.78 or higher. The following are acceptable: 1.79 or higher, 1.80 or higher, 1.81 or higher, 1.82 or higher, 1.83 or higher, 1.84 or higher, 1.85 or higher, 1.86 or higher, 1.87 or higher, 1.88 or higher, 1.89 or higher, 1.90 or higher, 1.91 or higher, 1.92 or higher, 1.93 or higher, 1.94 or higher, 1.95 or higher, 1.96 or higher, 1.97 or higher, 1.98 or higher, 1.99 or higher, and 2.00 or higher. On the other hand, the value of α may be 2.39 or less, 2.38 or less, 2.37 or less, 2.36 or less, 2.35 or less, 2.34 or less, 2.33 or less, 2.32 or less, 2.31 or less, 2.30 or less, 2.29 or less, 2.28 or less, 2.27 or less, 2.26 or less, 2.25 or less, 2.24 or less, 2.23 or less, 2.22 or less, 2.21 or less, 2.20 or less, 2.19 or less, 2.18 or less, 2.17 or less, 2.16 or less, 2.15 or less, 2.14 or less, 2.13 or less, 2.12 or less, 2.11 or less, 2.10 or less, 2.09 or less, 2.08 or less, 2.07 or less, 2.06 or less, 2.05 or less, 2.04 or less, 2.03 or less, 2.02 or less, or 2.01 or less.

[0050] In one embodiment, the lithium metal composite oxide powder may be in the form of primary particles, as described above, or it may have the form of secondary particles formed by the aggregation of primary particles. In this case, the average particle diameter (D50) of the secondary particles is not particularly limited, but is preferably, for example, 1 μm or more, 2 μm or more, 3 μm or more, or 4 μm or more. On the other hand, the average particle diameter (D50) of the secondary particles is preferably 30 μm or less, 25 μm or less, 20 μm or less, 17 μm or less, 15 μm or less, 12 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, or 4 μm or less.

[0051] Method for producing lithium metal composite oxide powder The method for producing the lithium metal composite oxide powder according to this embodiment may include, for example, the following steps. However, the lithium metal composite oxide powder according to this embodiment is not limited to that produced by the following method. In particular, the timing of adding the compounds that serve as raw materials for zirconium and titanium is not limited and can be changed by combining it with other manufacturing conditions. For example, depending on other manufacturing conditions, it may not be necessary to include zirconium in the precursor mixture. Conversely, it is not always possible to produce the lithium metal composite oxide powder according to this embodiment by all of the methods shown below. Precursor preparation step: Prepare a precursor complex compound containing at least nickel and zirconium. Precursor mixing step: The precursor complex compound prepared in the precursor preparation step is mixed with at least a titanium compound and a lithium compound, and optionally a zirconium compound, to prepare a precursor mixture. Calcination process: The precursor mixture is calcined to obtain a lithium metal composite oxide. Washing process: If necessary, the lithium metal composite oxide obtained by firing in the firing process is subjected to a washing treatment with water. Surface treatment process: If necessary, the lithium metal composite oxide obtained in the firing process or water washing process is subjected to surface treatment.

[0052] [Precursor preparation process] First, a precursor composite compound containing at least nickel and zirconium is synthesized. In one embodiment, it can be produced as an aggregate formed from primary particles. The method for synthesizing the precursor composite compound is not particularly limited, and for example, an aqueous solution containing at least nickel and a transition metal including zirconium, and various aqueous solutions of compounds containing other elements according to the composition of the target lithium metal composite oxide, can be dropped into a reaction vessel that is being stirred with an alkaline aqueous solution such as sodium hydroxide solution or ammonia solution as the mother liquor, while sodium hydroxide or the like is also dropped, and the pH is monitored and controlled to stay within an appropriate range, and the mixture is coprecipitation by a wet reaction to obtain, for example, a hydroxide, an oxide obtained by calcining hydroxide, a carbonate, etc.

[0053] Furthermore, in the reaction for synthesis, it is preferable to create a nitrogen atmosphere in the reaction vessel using an inert gas, or more preferably nitrogen gas for industrial purposes, from the time the alkaline aqueous solution which will serve as the mother liquor is prepared, thereby lowering the oxygen concentration in the reaction vessel system and the solution. If the oxygen concentration is too high, there is a risk that the co-precipitated hydroxide may be over-oxidized by the residual oxygen exceeding a predetermined amount, or that the formation of aggregates by crystallization may be hindered.

[0054] The aqueous solution of the transition metal is not particularly limited, but for example, an acidic aqueous solution is preferred, and in the case of a nickel compound, a sulfuric acid aqueous solution such as nickel sulfate aqueous solution is more preferred. Furthermore, one or more transition metals can be used as the aqueous solution.

[0055] The nickel compound is not particularly limited, but one or more can be selected from, for example, nickel sulfate, nickel oxide, nickel hydroxide, nickel nitrate, nickel carbonate, nickel chloride, nickel iodide, and metallic nickel.

[0056] The cobalt compound is not particularly limited, but one or more can be selected from, for example, cobalt sulfate, cobalt oxide, cobalt hydroxide, cobalt nitrate, cobalt carbonate, cobalt chloride, cobalt iodide, and metallic cobalt.

[0057] The manganese compound is not particularly limited, but for example, one or more selected from manganese sulfate, manganese oxide, manganese hydroxide, manganese nitrate, manganese carbonate, manganese chloride, manganese iodide, and metallic manganese can be used.

[0058] The zirconium compound is not particularly limited, but one or more selected from, for example, zirconium sulfate, zirconium oxide, zirconium nitrate, ammonium zirconium carbonate, zirconium chloride, zirconium iodide, and metallic zirconium can be used.

[0059] The titanium compound is not particularly limited, but for example, one or more selected from titanyl sulfate, titanium dioxide, titanium hydroxide, titanium nitrate, titanium carbonate, titanium chloride, titanium iodide, and metallic titanium can be used.

[0060] The aluminum compound is not particularly limited, but examples include aluminum sulfate, aluminum oxide, aluminum hydroxide, aluminum nitrate, aluminum carbonate, aluminum chloride, aluminum iodide, sodium aluminate, and metallic aluminum.

[0061] The iron compound is not particularly limited, but one or more selected from, for example, iron sulfate, iron oxide, iron hydroxide, iron nitrate, iron carbonate, iron chloride, iron iodide, and metallic iron can be used.

[0062] The niobium compound is not particularly limited, but one or more selected from, for example, niobium oxide, niobium chloride, lithium niobate, niobium iodide, etc., can be used.

[0063] The tungsten compound is not particularly limited, but one or more selected from, for example, tungsten oxide, sodium tungstate, ammonium paratungstate, hexacarbonyltungsten, tungsten sulfide, etc., can be used.

[0064] The magnesium compound is not particularly limited, but one or more selected from, for example, magnesium sulfate, magnesium oxide, magnesium hydroxide, magnesium nitrate, magnesium carbonate, magnesium chloride, magnesium iodide, and metallic magnesium can be used.

[0065] For other elements, one or more selected from sulfates, oxides, hydroxides, nitrates, carbonates, chlorides, iodides, and metals may be used.

[0066] The mixing ratio of each compound should be adjusted so that the amount of each element is in the desired ratio, taking into account the composition of the target lithium metal composite oxide.

[0067] The appropriate pH range for synthesizing precursor complex compounds is not particularly limited and can be determined to obtain the desired shape, such as secondary particle size and density. Generally, a range of 10 to 13 is sufficient.

[0068] The precursor complex compound obtained by the wet reaction is preferably subjected to washing, dehydration, and drying.

[0069] Washing the precursor complex compound removes impurities such as sulfate, carbonate, and sodium that may have been incorporated into the aggregated particles or adhered to the surface during the reaction. For small amounts, washing can be performed using a Buchner funnel or by sending the reaction suspension through a press filter for washing and dehydration. While pure water, sodium hydroxide solution, sodium carbonate solution, etc., can be used for washing, pure water is preferred industrially. However, if there is a large amount of residual sulfate, a sodium hydroxide solution with pH controlled according to the residual amount may be used.

[0070] Alternatively, the obtained precursor complex compound may be subjected to calcination by heat treatment at 200-800°C for 2-10 hours in an oxidizing atmosphere. Calcination can remove moisture and impurities from the precursor complex compound.

[0071] In one embodiment, zirconium may be supplied to a precursor composite compound that contains or does not contain zirconium by spraying a zirconium solution onto it or by applying a sol-gel coating.

[0072] [Precursor mixing step] Next, the synthesized precursor complex compound is mixed with at least a titanium compound and, if necessary, a zirconium compound and a lithium compound in predetermined ratios to prepare a precursor mixture. The mixing may be performed using a solvent system, in which the precursor complex compound and the lithium compound are each prepared as aqueous solutions and these solutions are mixed in predetermined ratios, or it may be performed using a non-solvent system, in which the powder of the precursor complex compound and the powder of the lithium compound are weighed in predetermined ratios and mixed dry.

[0073] The zirconium compound is not particularly limited and can be the same as that used in the precursor preparation step. For example, one or more can be selected from zirconium sulfate, zirconium oxide, zirconium nitrate, ammonium zirconium carbonate, zirconium chloride, zirconium iodide, and metallic zirconium.

[0074] The titanium compound is not particularly limited and can be the same as that used in the precursor preparation step. For example, one or more selected from titanyl sulfate, titanium dioxide, titanium hydroxide, titanium nitrate, titanium carbonate, titanium chloride, titanium iodide, and metallic titanium can be used.

[0075] The lithium compound is not particularly limited, and various lithium salts can be used. Specifically, one or more lithium compounds can be selected from, for example, anhydrous lithium hydroxide, lithium hydroxide hydrate, lithium nitrate, lithium carbonate, lithium acetate, lithium bromide, lithium chloride, lithium citrate, lithium fluoride, lithium iodide, lithium lactate, lithium oxalate, lithium phosphate, lithium pyruvate, lithium sulfate, and lithium oxide. Among these, it is preferable to use one or more selected from anhydrous lithium hydroxide and lithium hydroxide hydrate.

[0076] The precursor mixture may be further mixed with a compound of element M as described above. As the compound of element M, one or more can be selected from, for example, transition metals and other sulfates, oxides, hydroxides, nitrates, carbonates, chlorides, iodides, and metals.

[0077] The mixing ratio of the lithium compound and the precursor composite compound is not particularly limited, but can be appropriately adjusted so that the amount of lithium and the total amount of each element are in the desired ratio, taking into consideration the composition of the target lithium metal composite oxide.

[0078] [Firing process] In the production of lithium metal composite oxides containing at least a transition metal, lithiation and crystal growth proceed through calcination. The lithiation reaction requires a certain oxygen partial pressure. The lithiation reaction yields a lithium-containing lithium metal composite oxide. Subsequently, raising the temperature to a predetermined level promotes crystal growth.

[0079] The maximum temperature of the material to be fired (precursor mixture) during firing is preferably 650-1100°C, 670-1000°C, or 700-980°C. Furthermore, the firing time at the maximum temperature is preferably 1-24 hours, 1-20 hours, 1-15 hours, 1-10 hours, 2-9 hours, or 3-8 hours. By setting the firing temperature to be above the melting point of the lithium compound in the material to be fired, and by setting the maximum temperature and time to achieve the desired crystal growth or particle growth of the lithium-containing lithium metal composite oxide, the desired lithium metal composite compound can be obtained.

[0080] In general, calcination is carried out by filling containers such as crucibles or saggars with the precursor mixture obtained in the precursor mixing process. However, particularly in the lithiumization reaction, it becomes difficult to vent the generated gases to the outside and to diffuse the required oxygen concentration as the mixture approaches the bottom of the container. As a result, it becomes difficult to control the uniformity of the reaction and the primary particle size.

[0081] Therefore, when manufacturing the lithium metal composite oxide according to this embodiment, it is preferable to first perform pre-sintering under the following predetermined conditions in the firing process, and then perform main firing under the predetermined conditions. However, pre-sintering is not an essential step.

[0082] In this pre-calcination process, it is preferable to employ a calcination method that particularly promotes the lithiumization reaction. Specifically, this involves creating a state where the material to be calcined is more easily heated, allowing for the easy discharge of gases generated from lithium compounds, and diffusing gases with a high oxygen partial pressure into the material (particles). For example, it is possible to achieve desired properties by pre-calcining a smaller amount of material.

[0083] For pre-calcination of precursor mixtures, the precursor material can be packed into saggers or crucibles and calcined in a stationary furnace, roller hearth kiln, or pusher furnace, but a rotary kiln can be used to calcine the material while it is flowing.

[0084] The maximum temperature of the material to be pre-fired is not particularly limited, and is preferably adjusted according to the type of lithium compound used in the preparation of the material. This ensures that the precursor complex compound in the precursor mixture reacts with the lithium compound, allowing the lithiation reaction to proceed reliably and uniformly, preventing the generation of improper phases, and enabling the acquisition of the desired lithium metal complex oxide.

[0085] The atmosphere for pre-calcination is not particularly limited; any oxidizing atmosphere that ensures the lithiumization reaction proceeds reliably and uniformly is acceptable. For example, it is preferable to use a decarboxylated oxidizing gas atmosphere with a carbon dioxide concentration of 30 ppm or less, or an oxygen atmosphere with an oxygen concentration of 80% by volume or 90% by volume or more.

[0086] The pre-firing time is not particularly limited and should be any time that ensures the lithiumization reaction proceeds reliably and uniformly. For example, 1 to 10 hours or 2 to 8 hours is preferable.

[0087] The pre-calcined product obtained by pre-calcination may be further mixed with the aforementioned compound of element M. As the compound of element M, one or more can be selected from, for example, transition metals and other sulfates, oxides, hydroxides, nitrates, carbonates, chlorides, iodides, and metals.

[0088] In this way, the pre-fired material obtained through pre-sintering is subjected to a final firing at a higher temperature to promote crystal and particle growth. During this process, it is necessary to ensure reliable and uniform crystal growth to obtain a lithium metal composite oxide with the desired crystal structure.

[0089] The atmosphere for the final calcination is not particularly limited, but any atmosphere that ensures reliable and uniform crystal growth and has an oxygen partial pressure such that the transition metals contained in the precursor mixture to be calcined are not reduced, preferably with low moisture content and carbon dioxide concentration, is acceptable. For example, it is preferable to use a decarboxylated oxidizing gas atmosphere with a carbon dioxide concentration of 30 ppm or less, or an oxygen atmosphere with an oxygen concentration of preferably 80% by volume or 90% by volume or more.

[0090] The temperature for the main firing is not particularly limited as long as it is higher than the pre-firing temperature, and can be adjusted depending on the composition of the lithium metal composite oxide to be obtained. For example, it is preferable to adjust the maximum temperature to 700°C to 1100°C, 710°C to 1000°C, or 720°C to 980°C. By keeping the maximum temperature within the required range, it is possible to obtain a lithium metal composite oxide with a desired crystal structure and reduced unreacted components, and it is also possible to prevent a decrease in the battery characteristics of a non-aqueous electrolyte secondary battery using the obtained lithium metal composite oxide as the positive electrode. Furthermore, for example, when obtaining a lithium metal composite oxide in which the Ni content is 20 mol% to 80 mol% of the elements other than Li, it is preferable to fire the material at a temperature in which the maximum temperature of the material to be fired does not exceed 1100°C.

[0091] The firing time is not particularly limited and should be sufficient to form a lithium metal composite oxide having the desired crystal structure. For example, 1 to 15 hours, 2 to 12 hours, or 2 to 10 hours are preferred.

[0092] [Washing process] The lithium metal composite oxide obtained during the calcination process may contain impurities such as unreacted lithium compounds and lithium compounds that appear on the particle surface due to the crystalline structure during the primary and secondary calcination processes. Therefore, these impurities can be removed or reduced by, for example, washing with water and then heat treatment. Note that the washing step is not an essential component.

[0093] [Surface treatment process] By adding and mixing a compound of a predetermined element to the lithium metal composite oxide obtained in the secondary calcination or water washing process, and then subjecting it to heat treatment, the surface of the primary and / or secondary particles of the lithium metal composite oxide can be surface-treated with a compound of lithium and the added element. This can result in effects such as a reduction in lithium compounds remaining on the particle surface, improved lithium ion conductivity, and reduced reaction resistance. Note that the surface treatment process is not an essential component.

[0094] The elemental compounds added for the surface treatment described above can be selected from, for example, aluminum compounds, boron compounds, tungsten compounds, manganese compounds, cobalt compounds, phosphorus compounds, niobium compounds, strontium compounds, antimony compounds, zirconium compounds, titanium compounds, etc., and one or more of these can be used.

[0095] The heat treatment temperature is not particularly limited, but is preferably 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, or 250°C or higher. On the other hand, the heat treatment temperature is preferably 800°C or lower, 775°C or lower, 750°C or lower, 725°C or lower, 700°C or lower, 675°C or lower, 650°C or lower, 625°C or lower, 600°C or lower, 575°C or lower, 550°C or lower, 525°C or lower, 500°C or lower, 490°C or lower, 480°C or lower, 470°C or lower, 460°C or lower, 450°C or lower, 440°C or lower, 430°C or lower, 420°C or lower, 410°C or lower, or 400°C or lower.

[0096] The heat treatment time is not particularly limited, but is preferably, for example, 1 to 15 hours, 2 to 12 hours, or 2 to 10 hours.

[0097] Subsequently, the lithium metal composite oxide is pulverized using a pulverizer or the like to obtain lithium metal composite oxide powder.

[0098] <Nonaqueous electrolyte secondary battery> The non-aqueous electrolyte secondary battery according to this embodiment is equipped with a positive electrode containing the above-mentioned lithium metal composite oxide powder as a positive electrode active material for a non-aqueous electrolyte secondary battery, and the non-aqueous electrolyte secondary battery is composed of an electrolyte solution containing a positive electrode, a negative electrode and an electrolyte.

[0099] When manufacturing the positive electrode, a conductive agent and a binder are added to the lithium metal composite oxide according to this embodiment and mixed. Preferably, the conductive agent is acetylene black, carbon black, graphite, etc. Preferably, the binder is polytetrafluoroethylene, polyvinylidene fluoride, etc.

[0100] The negative electrode is not particularly limited, but can be a negative electrode active material such as lithium metal, graphite, or low-crystallinity carbon material, as well as one or more nonmetals or metal elements selected from Si, Al, Sn, Pb, Zn, Bi, and Cd, alloys containing them, or chalcogen compounds containing them.

[0101] The solvent for the electrolyte is not particularly limited, but an organic solvent containing one or more selected from carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate, or ethers such as dimethoxyethane, can be used.

[0102] As an electrolyte, in addition to lithium hexafluoride phosphate (LiPF6), one or more lithium salts selected from, for example, lithium perchlorate and lithium tetrafluoroborate, can be used dissolved in a solvent.

[0103] Although the embodiments of this disclosure have been described with specific examples, they can be implemented with appropriate modifications as long as they do not impede the effects of the present invention. [Examples]

[0104] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0105] <Sample Preparation> Samples for Examples 1-4 and Comparative Examples 1-3 were prepared according to the method described below.

[0106] (Preparation of Precursor Compound 1) Aqueous solutions of nickel sulfate, cobalt sulfate, manganese sulfate, and zirconium sulfate were mixed so that the molar ratio of Ni, Co, and Mn was Ni:Co:Mn = 50:25:25 and Zr / (Ni+Co+Mn+Zr) = 0.003 to obtain a metallic aqueous solution. In the reaction vessel, 10 L of pure water to which 300 g of sodium hydroxide solution and 510 g of ammonia solution had been added was prepared as the mother liquor. The reaction vessel was then filled with nitrogen gas at a flow rate of 0.7 L / min to create a nitrogen atmosphere, and the reaction was carried out under a nitrogen atmosphere.

[0107] Subsequently, while rotating the stirring blade at 950 rpm, the metal aqueous solution, sodium hydroxide aqueous solution, and ammonia aqueous solution were simultaneously added dropwise at a predetermined rate. The amount of alkaline solution added was adjusted so that the pH was 12.0. Through a crystallization reaction, Ni, Co, Mn, and Zr crystallized and coprecipitationd to form aggregated particles, yielding a coprecipitate.

[0108] Subsequently, the slurry in the reactor was separated into solid and liquid phases, and then washed with pure water to reduce residual impurities. The resulting coprecipitate was then dried in an atmospheric environment at 110°C for 12 hours to obtain precursor complex compound 1.

[0109] (Production of precursor complex compound 2) Aqueous solutions of nickel sulfate, cobalt sulfate, manganese sulfate, and zirconium sulfate were mixed so that the molar ratio of Ni, Co, and Mn was Ni:Co:Mn = 89:6:5 and Zr / (Ni+Co+Mn+Zr) = 0.003 to obtain a metallic aqueous solution. In the reaction vessel, 10 L of pure water to which 300 g of sodium hydroxide solution and 500 g of ammonia solution had been added was prepared as the mother liquor. The reaction vessel was then filled with nitrogen gas at a flow rate of 0.7 L / min to create a nitrogen atmosphere, and the reaction was carried out under a nitrogen atmosphere.

[0110] Subsequently, while rotating the stirring blade at 1000 rpm, the metal aqueous solution, sodium hydroxide aqueous solution, and ammonia aqueous solution were simultaneously added dropwise at a predetermined rate. The amount of alkaline solution added was adjusted so that the pH was 11.5. Through a crystallization reaction, Ni, Co, Mn, and Zr crystallized and coprecipitationd to form aggregated particles, yielding a coprecipitate.

[0111] Subsequently, the slurry in the reactor was separated into solid and liquid phases, and then washed with pure water to reduce residual impurities. The resulting coprecipitate was then dried in an atmospheric environment at 110°C for 12 hours to obtain precursor complex compound 2.

[0112] (Production of precursor complex compound 3) A metal aqueous solution was obtained by mixing nickel sulfate aqueous solution, cobalt sulfate, and manganese sulfate in a ratio (molar ratio) of Ni, Co, and Mn of Ni:Co:Mn = 50:25:25. In the reaction vessel, 10 L of pure water to which 300 g of sodium hydroxide aqueous solution and 505 g of ammonia water had been added was prepared as the mother liquor. The reaction vessel was then filled with nitrogen gas at a flow rate of 0.7 L / min to create a nitrogen atmosphere, and the reaction was carried out under a nitrogen atmosphere.

[0113] Subsequently, while rotating the stirring blade at 950 rpm, the metal aqueous solution, sodium hydroxide aqueous solution, and ammonia aqueous solution were simultaneously added dropwise at a predetermined rate. The amount of alkaline solution added was adjusted so that the pH was 12.1. Through this crystallization reaction, Ni, Co, and Mn crystallized and coprecipitationd to form aggregated particles, yielding a coprecipitate.

[0114] Subsequently, the slurry in the reactor was separated into solid and liquid phases, and then washed with pure water to reduce residual impurities. The resulting coprecipitate was then dried in an atmospheric environment at 110°C for 12 hours to obtain precursor complex compound 3.

[0115] (Example 1) Precursor complex compound 1, anhydrous lithium hydroxide, and TiO2 were weighed so that the ratio (molar ratio) of the total amount of Ni, Co, Mn, Zr, and Ti to Ti was Ti / (Ni+Co+Mn+Zr+Ti)=0.004, and the ratio (molar ratio) of Li to the total amount of Ni, Co, Mn, Zr, and Ti was Li / (Ni+Co+Mn+Zr+Ti)=1.055. These were then mixed using a mixer to prepare a precursor mixture.

[0116] Next, the precursor mixture was calcined in an electric furnace under an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 850°C for 5 hours. After cooling, it was pulverized in a pulverizer to obtain a lithium metal composite oxide powder sample. In the lithium metal composite oxide powder sample, the average particle size of the secondary particles was 4.1 μm.

[0117] (Example 2) Precursor complex compound 1, anhydrous lithium hydroxide, ZrO2, and TiO2 were weighed so that the molar ratio of the total amount of Ni, Co, Mn, Zr, and Ti was Zr / (Ni+Co+Mn+Zr+Ti)=0.005 (Zr=0.2 mo% was added as ZrO2 during mixing), Ti / (Ni+Co+Mn+Zr+Ti)=0.015, and the molar ratio of Li to the total amount of Ni, Co, Mn, Zr, and Ti was Li / (Ni+Co+Mn+Zr+Ti)=1.055. These were then mixed using a mixer to prepare a precursor mixture.

[0118] Next, the precursor mixture was calcined in an electric furnace under an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 850°C for 5 hours. After cooling, it was pulverized in a pulverizer to obtain a lithium metal composite oxide powder sample. In the lithium metal composite oxide powder sample, the average particle size of the secondary particles was 3.9 μm.

[0119] [Example 3] Precursor complex compound 1, anhydrous lithium hydroxide, TiO2, and Al(OH)3 were weighed so that the molar ratios of Ni / (Ni+Co+Mn+Zr+Ti+Al)=0.004 and Al / (Ni+Co+Mn+Zr+Ti+Al)=0.003, and the molar ratio of Li to the total amount of Ni, Co, Mn, Zr, Ti, and Al was Li / (Ni+Co+Mn+Zr+Ti+Al)=1.052. These were then mixed using a mixer to prepare a precursor mixture.

[0120] Next, the precursor mixture was calcined in an electric furnace under an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 850°C for 5 hours. After cooling, it was pulverized in a pulverizer to obtain a lithium metal composite oxide powder sample. In the lithium metal composite oxide powder sample, the average particle size of the secondary particles was 4.2 μm.

[0121] [Example 4] Precursor complex compound 2, anhydrous lithium hydroxide, and TiO2 were weighed so that the ratio (molar ratio) of the total amount of Ni, Co, Mn, Zr, and Ti to Li was Ti / (Ni+Co+Mn+Zr+Ti)=0.015, and the ratio (molar ratio) of Li to the total amount of Ni, Co, Mn, Zr, and Ti was Li / (Ni+Co+Mn+Zr+Ti)=1.046. These were then mixed using a mixer to prepare a precursor mixture.

[0122] Next, the precursor mixture was calcined in an electric furnace under an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 840°C for 5 hours. After cooling, it was pulverized in a pulverizer to obtain a lithium metal composite oxide powder sample. In the lithium metal composite oxide powder sample, the average particle size of the secondary particles was 4.6 μm.

[0123] [Comparative Example 1] Precursor complex compound 1 and anhydrous lithium hydroxide were weighed so that the ratio (molar ratio) of Li to the total amount of Ni, Co, Mn, and Zr was Li / (Ni+Co+Mn+Zr) = 1.052, and these were mixed using a mixer to prepare a precursor mixture.

[0124] Next, the precursor mixture was calcined in an electric furnace under an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 850°C for 5 hours. After cooling, it was pulverized in a pulverizer to obtain a lithium metal composite oxide powder sample. In the lithium metal composite oxide powder sample, the average particle size of the secondary particles was 4.0 μm.

[0125] [Comparative Example 2] Precursor complex compound 3, anhydrous lithium hydroxide, and TiO2 were weighed so that the ratio (molar ratio) of Ni, Co, Mn, and Ti to the total amount of Li was Ti / (Ni+Co+Mn+Ti)=0.004, and the ratio (molar ratio) of Li to the total amount of Ni, Co, Mn, and Ti was Li / (Ni+Co+Mn+Ti)=1.053. These were then mixed using a mixer to prepare a precursor mixture.

[0126] Next, the precursor mixture was calcined in an electric furnace under an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 850°C for 5 hours. After cooling, it was pulverized in a pulverizer to obtain a lithium metal composite oxide powder sample. In the lithium metal composite oxide powder sample, the average particle size of the secondary particles was 4.2 μm.

[0127] [Comparative Example 3] Precursor complex compound 3, anhydrous lithium hydroxide, ZrO2, and TiO2 were weighed so that the molar ratios of Ni / (Ni+Co+Mn+Zr+Ti)=0.003 and Ti / (Ni+Co+Mn+Zr+Ti)=0.015, and the molar ratio of Li to the total amount of Ni, Co, Mn, Zr, and Ti was Li / (Ni+Co+Mn+Zr+Ti)=1.055. These were then mixed using a mixer to prepare a precursor mixture.

[0128] Next, the precursor mixture was calcined in an electric furnace under an oxygen atmosphere (oxygen concentration: 97 vol%) at a maximum temperature of 850°C for 5 hours. After cooling, it was pulverized in a pulverizer to obtain a lithium metal composite oxide powder sample. In the lithium metal composite oxide powder sample, the average particle size of the secondary particles was 4.0 μm.

[0129] <Evaluation of the sample> The samples from Examples 1-4 and Comparative Examples 1-3 were evaluated according to the method described below. The results are shown below.

[0130] [Composition of precursor complex compounds and lithium metal complex oxides] 0.2 g of the precursor complex compound or lithium metal complex oxide was heated and dissolved in 25 mL of 20% hydrochloric acid solution. After cooling, the solution was transferred to a 100 mL volumetric flask, and pure water was added to prepare the adjusted solution. The constituent elements of this adjusted solution were quantified using ICP-AES [Optima8300, PerkinElmer Corporation] to confirm that the precursor complex compound and lithium metal complex oxide powder samples were in the correct charging ratio for each metal element.

[0131] [Method for measuring particle size distribution] The average particle size (D50) of lithium metal composite oxide powder samples was measured by volume using a wet laser method with a laser particle size distribution analyzer (Microtrac HRA, manufactured by Nikkiso Co., Ltd.).

[0132] [Line analysis using two-dimensional high-resolution secondary ion mass spectrometry] Line analysis was performed using a two-dimensional high-resolution secondary ion mass spectrometer (NanoSIMS 50L: CAMECA) to obtain information about the particle surface and interior. Specifically, oxygen was used as the primary ion species, and the primary ion acceleration voltage was set to 16kV. The analysis was then performed based on the detected secondary ions.

[0133] The observed lithium metal composite oxide powder samples were fixed with resin, cross-sectionally processed using the BIB method, and charge compensation was performed by metal coating the processed surfaces. Except for the metal coating process, all sampling-related operations were carried out in an inert atmosphere. Afterward, the samples were placed on a sample stage, and the outermost surface was cleaned with an ion beam immediately before observation.

[0134] Prior to observation using a two-dimensional high-resolution secondary ion mass spectrometer, SEM observation was performed to select particles from the lithium metal composite oxide powder sample whose particle size was 0.95 to 1.05 times the average particle size (D50). At this time, the coordinates of the selected secondary particles were recorded, and these coordinates were used as a reference during the observation with the two-dimensional high-resolution secondary ion mass spectrometer.

[0135] D50 was measured using a laser-type particle size distribution analyzer (Microtrac HRA, manufactured by Nikkiso Co., Ltd.) and the wet laser method, based on volume.

[0136] The lines used in the line profile were set to a length such that the length from end to end was 1.5 times the line segment representing the maximum particle diameter of the secondary particle selected for observation. Three lines were selected that form a 60° angle with each other, and whose length is at least 0.6 times the length of the selected line passes through the interior of the particle.

[0137] The line profile spacing was set to 80 nm for Ti and 500 nm for Zr. The line profiles were smoothed by taking a moving average of the intensity of five points: the center point of the numerical value and two points before and after it, and this was used for analysis.

[0138] (Near surface and maximum strength) For each of the three lines, the area between the point in the line profile where the count exceeds 10 times the background and the point where the line profile is moved 0.3 times the maximum particle diameter of the observed particle from those points was defined as the near-surface area. Within this area, the maximum counts for Zr and Ti were determined. Subsequently, the arithmetic mean of the maximum counts for each of the three lines was defined as the maximum intensity.

[0139] (Near-center and average intensity) For each of the three lines, the area inside the surface vicinity at both ends of the particle was defined as the vicinity of the center. The arithmetic mean of the Zr and Ti counts within this range was calculated for each of the three lines. Then, the arithmetic mean of the arithmetic mean of the counts for each of the three lines was calculated and defined as the average intensity.

[0140] (Background and average intensity) For each of the three lines, the background was defined as an area in the cross-sectional SEM image where no particles were present, but not as a region near the surface where the line profile was elevated. The counts of Zr and Ti were measured at 20 background points (60 points in total) randomly selected from each of the three lines, and their arithmetic mean was used as the average intensity.

[0141] (Intensity ratio and coefficient of variation of intensity) From the values ​​obtained above, we calculated the ratio of the maximum Zr intensity near the particle surface to the average Zr intensity near the center of the lithium metal composite oxide particle (Zr intensity ratio), the coefficient of variation of the ratio of the average Zr intensity near the center of the particle cross-section to the average background Zr intensity (coefficient of variation of Zr intensity), the ratio of the maximum Ti intensity near the particle surface to the average Ti intensity near the center of the particle (Ti intensity ratio), and the coefficient of variation of the ratio of the Ti intensity near the center of the particle to the average background Ti intensity (coefficient of variation of Ti intensity).

[0142] [Method for calculating lattice constants of lithium metal composite oxide powder samples by XRD diffraction] Using an X-ray diffractometer [SmartLab, manufactured by Rigaku Corporation], XRD diffraction data was obtained for a lithium metal composite oxide powder sample under the following X-ray diffraction conditions. Rietveld analysis was then performed using the XRD diffraction data, referencing "RAYoung, ed., "The Rietveld Method", Oxford University Press (1992)". From these results, the a-axis length (the lattice constant of the a-axis) and the c-axis length (the lattice constant of the c-axis) were calculated. (X-ray diffraction conditions) Source: Cu-Kα Acceleration voltage and current: 45kV and 200mA Sampling width: 0.02 degrees. Scan width: 15deg.~122deg. Scan speed: 1.0 step / second Divergence slit: 2 / 3 degree. Light-receiving slit width: 0.15 mm Scattering slit: 2 / 3 degree.

[0143] [Battery characteristics of non-aqueous electrolyte secondary batteries] (Fabrication of coin cells using lithium metal composite oxide powder samples) A 2032-type coin cell using a lithium metal composite oxide powder sample as the positive electrode active material was fabricated using the positive electrode, negative electrode, and electrolyte prepared by the following method.

[0144] ·Positive electrode Acetylene black and graphite were used as conductive agents in a ratio of acetylene black:graphite = 1:1 (by weight), and polyvinylidene fluoride was used as a binder. The lithium metal composite oxide powder sample, conductive agent, and binder were blended in a ratio of sample:conductive agent:binder = 90:6:4 (by weight), and a slurry of these was mixed with N-methylpyrrolidone and applied to aluminum foil. This was dried at 110°C to produce a sheet, and after punching out this sheet to a diameter of 15 mm, the density of the composite material was 3.0 g / cm³. 3 The material rolled in this manner was used as the positive electrode.

[0145] ·Negative electrode A 500 μm thick lithium foil, punched out to a diameter of 16 mm, was used as the negative electrode.

[0146] ·Electrolyte A mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) was prepared with a volume ratio of EC:DMC = 1:2. This mixture was then mixed with 1 M LiPF6, which served as the electrolyte, to create the electrolyte solution.

[0147] (Measurement of initial discharge capacity) Using the coin cells manufactured by the method described above, constant current charging was performed at a current density equivalent to 0.1C up to 4.30V (upper voltage) in a 25°C environment, followed by constant voltage charging until the current became 0.005C. The capacity at this time was defined as the initial charging capacity (mAh / g).

[0148] Next, after a 5-minute pause, constant current discharge was performed under the same conditions at a current density of 0.1C up to 3.00V, followed by a 5-minute pause to measure the initial discharge capacity (mAh / g).

[0149] [-10℃ Low-Temperature DCR Measurement] After measuring the initial charge / discharge capacity as described above, the battery was further charged at a constant current density of 0.1C to 4.3V (upper voltage) in a 25°C environment, and then charged at a constant voltage until the current became 0.01C. Next, after a 5-minute pause, the battery was discharged at a constant current density of 0.1C to 3.0V in the same environment, and then paused for 5 minutes. This operation was repeated twice, and then the battery was charged again to 4.3V under the same conditions.

[0150] Subsequently, after 1 hour in a -10°C environment, the battery was discharged at a constant current density of 0.1C to achieve a voltage corresponding to 20% State of Charge (SOC), based on the discharge capacity during the second discharge cycle. After a 5-minute pause, the battery was discharged at a current value corresponding to 10% SOC, and the DC resistance (DCR) was measured by measuring the voltage difference at that time.

[0151] [Measurement of volume retention rate after high-temperature storage] Cells were prepared as follows, and the volume retention rate after high-temperature storage was measured.

[0152] (Positive electrode) The electrode slurry was prepared by mixing a lithium metal composite oxide powder sample and carbon black as the positive electrode active material with polyvinylidene fluoride (PVdF) in N-methylpyrrolidinone (NMP). The resulting slurry was coated onto aluminum foil (thickness = 17 μm) using a roll coater, dried in a hot air chamber, vacuumed, and further dried at 130°C for 8 hours. The resulting electrode load was 16.4 mg / cm². 2 It was found that the electrodes were 3.4 g / cm³. 3 It was pressed using a roll press machine that produced a certain density.

[0153] (Negative electrode) An aqueous slurry was prepared by mixing graphite and carbon black with CMC (carboxymethylcellulose) and SBR (styrene-butadiene rubber). The resulting slurry was coated onto copper foil (thickness = 9 μm) using a roll coater and dried in a hot air chamber (80°C to 120°C). The resulting electrode had a load of 10 mg / cm².2 It was found that the electrodes were 1.4 g / cm³. 3 It was pressed using a roll press machine that produced a certain density.

[0154] (Electrolyte composition) It was prepared by dissolving 1.0 mol / L LiPF6 in a mixture of 30% by mass of ethylene carbonate (EC) and 70% by mass of diethyl carbonate (DMC), and then adding 1% by mass of vinylene carbonate (VC) and 1.5% by mass of fluoroethylene carbonate (FEC).

[0155] (Electrochemical cell) A pouch cell (170 mAh) containing a cathode electrode and a graphite anode electrode, along with a polyolefin separator layered between the cathode and anode, was assembled into an Ar-filled glove box. Subsequently, 0.7 μL of electrolyte composition was introduced into the laminated pouch cell and sealed in the Ar-filled glove box.

[0156] (Aging cycle and storage) The pouch cell was charged to 4.2V with a current density of 0.2C, then under constant current charging conditions, constant voltage charging was performed until the current became 0.005C, until the state of charge (SOC) reached 10%. Next, it was discharged to 2.5V with a constant current density of 0.2C. After that, a degassing process was applied at 25°C in an Ar atmosphere. Furthermore, the cell was charged again at 25°C to 4.2V with a current density of 0.2C until the SOC reached 10%, and then stored at 45°C for 24 hours.

[0157] After aging cycles and storage, the batteries were charged at 25°C to 4.2V with a current density of 0.2C. After constant current charging, constant voltage charging was performed until the current reached 0.005C. After a 5-minute pause, constant current discharge was performed to 2.5V with a current density of 0.2C. The battery capacity at this time was defined as the initial charge / discharge capacity.

[0158] (High-temperature storage characteristics test) After evaluating the initial charge / discharge capacity, the pouch cells were charged at 25°C with a current density of 0.2C until the State of Charge (SOC) reached 80%. After a 5-minute rest, they were discharged at 1C for 10 seconds. The Discharge Coverage (DCR) was calculated from the difference between the OCV and CCV during this 10-second discharge, divided by the 1C current value.

[0159] Next, the cells were charged at 1C for 10 seconds to achieve a State of Charge (SOC) of 80%. Then, they were stored in a constant temperature bath at 60°C for 6 days. After removing the pouch cells from the constant temperature bath and lowering the temperature to 25°C, the capacity after high-temperature storage was measured by charging at 25°C to 4.2V with a current density of 0.2C, then constant current charging followed by constant voltage charging until the current reached 0.005C, a 5-minute pause, and finally constant current discharge to 2.5V with a current density of 0.2C.

[0160] The above high-temperature storage characteristics test was repeated four times. The discharge capacity of the fourth test relative to the initial discharge capacity was defined as the capacity retention rate after high-temperature storage. In addition, the DCR value of the fourth test relative to the initial DCR value was defined as the DCR increase rate after high-temperature storage.

[0161] Furthermore, the DCR increase rate after high-temperature storage for Comparative Example 1 was set to 100, and the relative values ​​for the other examples and comparative examples were calculated.

[0162] [Evaluation of the cell anode after evaluating high-temperature storage characteristics using XRF] By performing XRF (X-ray fluorescence analysis) measurements on the anode that was disassembled after the aforementioned high-temperature storage characteristics test, the ratio of Mn and Ni dissolved into the electrolyte from the lithium metal composite oxide sample during the high-temperature storage characteristics test was determined.

[0163] (Dismantling of pouch cells after evaluation of high-temperature storage characteristics) After the high-temperature storage characteristics test described above, the cells were discharged at 25°C to 2.5V at 0.2C. The tested pouch cells were then placed in an Ar atmosphere glove box, and the adhesive portion of the pouch cells was cut off with ceramic scissors. The negative electrode was recovered from the pouch cell, immersed in dimethyl carbonate (DMC) for approximately 5 minutes, the excess liquid was wiped off with a Kimwipe, and the cells were dried under reduced pressure for 20 minutes in the sample exchange chamber of the glove box.

[0164] (Negative electrode evaluation using XRF) The obtained positive electrode was punched out using a Φ16 mm die, and its components were analyzed using a fluorescence X-ray analyzer (ZSX Primus II, Rigaku Corporation). The sample was stored in an Ar atmosphere until immediately before measurement, and the measurement was performed in an air atmosphere. A Rh X-ray tube was used. The measurement range (target elements) was C to U. Based on the mass percentages of Mn and Ni calculated from this analysis, the mass percentage ratio of Mn to Ni was calculated.

[0165] <Evaluation Results> The above evaluations were performed on Examples 1-4 and Comparative Examples 1-3. The results are shown in Table 1.

[0166] [Table 1]

Claims

1. A lithium metal composite oxide powder comprising particles of a lithium metal composite oxide containing at least Li, Ni, Zr, and Ti, When the lithium metal composite oxide particles were analyzed cross-sectionally using a two-dimensional high-resolution secondary ion mass spectrometer, The ratio of the maximum Zr intensity near the surface of the lithium metal composite oxide particles to the average Zr intensity near the center of the lithium metal composite oxide particles is 1.5 or more and 3.5 or less. The ratio of the maximum Ti intensity near the surface of the lithium metal composite oxide particles to the average Ti intensity near the center of the lithium metal composite oxide particles is 0.60 or more and 2.6 or less. Lithium metal composite oxide powder.

2. When the lithium metal composite oxide particles were analyzed cross-sectionally using a two-dimensional high-resolution secondary ion mass spectrometer, The coefficient of variation of the ratio of the average intensity of Zr near the center of the cross-section of the lithium metal composite oxide particles to the average intensity of Zr in the background is 0.10 or more and 1.4 or less. The lithium metal composite oxide powder according to claim 1.

3. When the lithium metal composite oxide particles were analyzed cross-sectionally using a two-dimensional high-resolution secondary ion mass spectrometer, The coefficient of variation of the ratio of the Ti intensity near the center of the lithium metal composite oxide particles to the average background Ti intensity is 0.10 or more and 1.5 or less. The lithium metal composite oxide powder according to claim 1 or 2.

4. The aforementioned lithium metal composite oxide has a layered rock salt structure, General formula Li ａ Ni ｘ Co ｙ Mn ｚ Zr ｕ Ti ｖ M ｗ O α (In the formula, M is one or more elements other than Li, Ni, Co, Mn, Zr, Ti, and O, and is expressed as follows: 0.90 ≤ a ≤ 1.4, x + y + z + u + v + w = ​​1.00, 0 < u ≤ 0.015, 0 < v ≤ 0.030, 1.60 ≤ α ≤ 2.40) The lithium metal composite oxide powder according to claim 1 or 2.

5. The lithium metal composite oxide powder is included in claim 1 or 2. Positive electrode active material for non-aqueous electrolyte secondary batteries.

6. The positive electrode active material for a non-aqueous electrolyte secondary battery is provided as described in claim 5. Nonaqueous electrolyte secondary battery.

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