Positive electrode material powder, and positive electrode and lithium secondary battery including same

Abstract

A positive electrode material powder according to the present invention includes a positive electrode active material including lithium-nickel oxide particles having a Ni content of 50 mol%-80 mol% among all metals excluding lithium, wherein the lithium-nickel oxide particles may be in a single-particle form consisting of one single nodule, or a quasi-single-particle form as a composite of 30 nodules or less, and a PCF value represented by equation (1) may satisfy 2.0 or more to 3.4 or less. [Equation (1)] In equation (1), SBET is a BET specific surface area (unit: m2 / g) of the positive electrode material powder, P0 is an intensity of maximum peak (vol%) in a volume cumulative particle size distribution of the positive electrode material powder as measured by using a laser diffraction method, D50 is a particle size at a volume cumulative value of 50 % in the volume cumulative particle size distribution of the positive electrode material powder, Dmin is the smallest particle size in the volume cumulative particle size distribution of the positive electrode material powder, and Dmax is the largest particle size in the volume cumulative particle size distribution of the positive electrode material powder.

Description

Cathode material powder, cathode and lithium secondary battery containing same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0092287, filed July 17, 2023, Korean Patent Application No. 10-2023-0098548, filed July 27, 2023, Korean Patent Application No. 10-2024-0094050, filed July 16, 2024, and Korean Patent Application No. 10-2024-0094051, filed July 16, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a cathode material powder, a cathode containing the same, and a lithium secondary battery, and more particularly, to a cathode material powder having excellent continuous charging characteristics and generating less fine particles during electrode manufacturing, and a cathode containing the same and a lithium secondary battery.

[0005]

[0006] A lithium secondary battery is generally composed of a positive electrode, a negative electrode, a separator, and an electrolyte, and the positive electrode and negative electrode include an active material capable of intercalating and deintercalating lithium ions.

[0007] Lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2 or LiMnO4, etc.), and lithium iron phosphate compound (LiFePO4) have been used as cathode active materials for lithium secondary batteries. Among these, lithium cobalt oxide has the advantages of high operating voltage and excellent capacity characteristics, but the high price of cobalt, which is the raw material, and its supply are unstable, making it difficult to commercially apply it to large-capacity batteries. Lithium nickel oxide has poor structural stability, making it difficult to achieve sufficient cycle life characteristics. On the other hand, lithium manganese oxide has excellent stability but has the problem of poor capacity characteristics. Therefore, lithium composite transition metal oxides containing two or more transition metals have been developed to complement the problems of lithium transition metal oxides containing only Ni, Co, or Mn. Among these, lithium nickel cobalt manganese oxide containing Ni, Co, and Mn (hereinafter simply referred to as 'NCM-based lithium composite transition metal oxides') are widely used in the field of electric vehicle batteries.

[0008] Meanwhile, the conventionally developed NCM-based lithium composite transition metal oxides were generally in the form of spherical secondary particles in which tens to hundreds of primary particles were aggregated. However, when applying NCM-based lithium composite transition metal oxides in the form of secondary particles in which many primary particles are aggregated, there is a problem in that the primary particles are likely to break during the rolling process during the manufacture of the positive electrode, and cracks occur inside the particles during the charge and discharge process. When the particles of the positive electrode active material break or crack, the contact area with the electrolyte increases, which increases gas generation and active material degradation due to side reactions with the electrolyte, and this causes a problem in that the life characteristics are reduced.

[0009] To solve this problem, a technology has been proposed to manufacture single particle-type cathode active materials rather than secondary particles by increasing the sintering temperature during the manufacture of NCM-type lithium composite transition metal oxides. In the case of single particle-type cathode active materials, the contact area with the electrolyte is smaller than that of conventional secondary particle-type cathode active materials, so there is less side reaction with the electrolyte, and the particle strength is superior, so there is less particle breakage during electrode manufacture. Therefore, when single particle-type cathode active materials are applied, there are advantages such as excellent gas generation and life characteristics.

[0010] However, in the case of a positive electrode active material in the form of a single particle, the interface between the primary particles that serves as a passage for lithium ions to move within the particle is small, so lithium mobility is low, and the capacity characteristics are lower than in the case of a positive electrode active material in the form of a secondary particle.

[0011] One way to increase the capacity of a single particle type positive electrode active material is to increase the operating voltage. However, when the operating voltage of NCM type lithium composite transition metal oxide is 4.3 V or higher, especially 4.35 V or higher, the side reaction with the electrolyte becomes severe, transition metal ions are eluted, and phase transition of the crystal structure occurs, causing a rapid deterioration in battery performance.

[0012] In particular, the main reason for the severe side reaction with the electrolyte at high voltages of 4.35 V or higher is that the generation of fine particles increases due to particle breakage during electrode manufacturing, but the generation of fine particles cannot be sufficiently suppressed with only the conventional single particle type positive electrode active material.

[0013] Therefore, there is a need for the development of a cathode material powder that can be stably operated at high voltage, generates less fine dust during rolling, and exhibits excellent continuous charging characteristics.

[0014]

[0015] One object of the present invention is to solve the above-mentioned problem by controlling the powder properties of the cathode material powder and thereby providing cathode material powder that generates less fine particles during rolling.

[0016] In addition, another object of the present invention is to provide a positive electrode and a lithium secondary battery including the positive electrode material powder described above.

[0017]

[0018] In one aspect, the present invention provides a cathode powder comprising a cathode active material including lithium nickel-based oxide particles having a Ni content of 50 mol% to 80 mol% among all metals excluding lithium, wherein the lithium nickel-based oxide particles are in the form of single particles consisting of one single nodule or quasi-single particles consisting of a composite of 30 or fewer nodules, and a PCF value expressed by the following formula (1) is 2.0 or more and 3.4 or less.

[0019] Equation (1):

[0020]

[0021] In the above equation (1), the S BET is the BET specific surface area of ​​the above cathode material powder (unit: m 2 / g), and the above P0 is the intensity of the maximum peak (vol%) in the volume cumulative particle size distribution measured using laser diffraction of the above cathode material powder, and the above D 50 is the particle size when the volume accumulation amount is 50% in the volume accumulation particle size distribution of the above cathode material powder, and the above D min is the minimum particle size in the volume cumulative particle size distribution of the above cathode material powder, and the above D max is the maximum particle size in the volume cumulative particle size distribution of the above cathode material powder.

[0022] The above lithium nickel-based oxide particles can be represented by the following [chemical formula 1].

[0023] [Chemical Formula 1]

[0024] Li a Ni b Co c Mn d M 1 e O2

[0025] In the above chemical formula 1, M 1 It may be at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.8≤a≤1.2, 0.5≤b≤0.8, 0 <c≤0.3, 0<d≤0.4, 0≤e≤0.2일 수 있다.

[0026] The above cathode material powder has a BET specific surface area of ​​0.2 m 2 / g or more than 1.3m 2 / g can be less.

[0027] The above cathode material powder may have a P0 of 8 or more.

[0028] D of the above cathode powder 50 It can be 1㎛ or more and 10㎛ or less.

[0029] D of the above cathode powder min It can be 0.75㎛ or more and 2.0㎛ or less.

[0030] D of the above cathode powder max It can be 8㎛ or more and 18㎛ or less.

[0031] The above cathode material powder may have an SP value expressed by the following formula (2) of 0.20 or more and 0.33 or less.

[0032] Equation (2):

[0033]

[0034] The PCF value of the above cathode material powder may be 2.5 or more and 3.2 or less.

[0035] When the above cathode material powder is pressurized at 9 tons, the generation rate of fine particles having a particle size of 1㎛ or less may be 3% by volume or less.

[0036]

[0037] In another aspect, the present invention provides a cathode comprising the cathode material powder described above.

[0038]

[0039] In another aspect, the present invention provides a lithium secondary battery including the above-mentioned positive electrode, negative electrode, a separator interposed between the positive electrode and negative electrode, and an electrolyte.

[0040] The above lithium secondary battery may have a charging end voltage of 4.35 V or higher when operated.

[0041]

[0042] The cathode material powder according to the present invention is characterized in that the PCF value satisfies the range of the present invention. A cathode using a cathode material powder whose PCF is outside the range of the present invention does not have a particle size value of an appropriate BET specific surface area of ​​a cathode active material and an appropriate volume cumulative particle size distribution, so that particle breakage increases during cathode rolling, and side reactions with the electrolyte become severe during high-voltage driving, resulting in poor continuous charging characteristics. In contrast, a cathode material powder whose PCF satisfies the range of the present invention exhibits less particle breakage during cathode rolling, and thus side reactions with the electrolyte are reduced during high-voltage driving, resulting in excellent continuous charging characteristics.

[0043]

[0044] Figure 1 is a graph showing the volume cumulative particle size distribution (PSD) according to Experimental Examples 1 and 2 of the cathode material powder manufactured by Example 1.

[0045] Figure 2 is a graph showing the volume cumulative particle size distribution (PSD) of the cathode material powder manufactured by Comparative Example 2 according to Experimental Examples 1 and 2.

[0046] Figure 3 is a graph showing the results of evaluating the leakage current during continuous charging according to Experimental Example 3.

[0047] Figure 4 is a graph showing only the current in the graph of Figure 3 above.

[0048] Figure 5 is a graph showing only the voltage in the graph of Figure 3 above.

[0049]

[0050] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0051] In the present invention, a "single particle" is a particle composed of one single nodule. In the present invention, a "quasi-single particle" means a composite particle formed of 30 or fewer nodules.

[0052] In the present invention, "nodule" means a particle unit body constituting a single particle and a pseudo-single particle, and the nodule may be a single crystal lacking a crystalline grain boundary, or a polycrystal in which no grain boundary exists in appearance when observed with a scanning electron microscope (SEM) at a magnification of 5,000 to 20,000 times. The average particle diameter of the nodule may be measured as the arithmetic mean value of the particle diameters of each nodule measured using a scanning electron microscope (SEM).

[0053] In the present invention, "secondary particle" refers to a particle formed by the agglomeration of tens to hundreds of primary particles. More specifically, the secondary particle is an agglomerate of 40 or more primary particles.

[0054] The expression "particle" used in the present invention may include any one or all of single particles, quasi-single particles, primary particles, nodules, and secondary particles.

[0055] In the present invention, the “specific surface area” is measured by the BET method, and specifically, can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mini II of BEL Japan.

[0056] In the present invention, “P0” “D min ”, “D 50 ” and “D max "is the particle size value of the volume cumulative particle size distribution of the positive electrode active material powder measured using the laser diffraction method. Specifically, P0 is the intensity of the maximum peak (vol%) appearing in the volume cumulative particle size distribution of the positive electrode active material powder, and D min is the minimum particle size appearing in the volume cumulative particle size distribution of the above positive electrode active material powder, and D 50 is the particle size when the volume accumulation amount shown in the volume accumulation particle size distribution of the above positive electrode active material powder is 50%, and D max is the maximum particle size appearing in the volume cumulative particle size distribution of the positive electrode active material powder. The particle size value of the volume cumulative particle size distribution can be measured, for example, by dispersing the positive electrode active material powder in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, and then obtaining a volume cumulative particle size distribution graph.

[0057]

[0058] The present inventors have conducted repeated research to develop a positive electrode powder for a lithium secondary battery with less particle breakage during electrode rolling and excellent continuous charging characteristics, and as a result, have discovered that when the powder characteristics of the positive electrode powder satisfy a specific relationship, particle breakage during rolling is reduced and side reactions with the electrolyte are minimized, thereby realizing excellent battery characteristics at high voltage, thereby completing the present invention.

[0059]

[0060] cathode powder

[0061] Hereinafter, the cathode material powder according to the present invention will be described.

[0062] Specifically, the cathode material powder according to the present invention is a cathode material powder including a cathode active material including lithium nickel-based oxide particles having a Ni content of 50 mol% to 80 mol% among all metals excluding lithium, wherein the lithium nickel-based oxide particles are in the form of single particles consisting of one single nodule or quasi-single particles that are complexes of 30 or fewer nodules, and are cathode material powders that satisfy a PCF value expressed by the following formula (1) of 2.0 or more and 3.4 or less.

[0063] Equation (1):

[0064]

[0065] In the above equation (1), the S BET is the BET specific surface area of ​​the above cathode material powder (unit: m 2 / g), and the above P0 is the intensity of the maximum peak (vol%) in the volume cumulative particle size distribution measured using laser diffraction of the above cathode material powder, and the above D 50 is the particle size when the volume accumulation amount is 50% in the volume accumulation particle size distribution of the above cathode material powder, and the above D min is the minimum particle size in the volume cumulative particle size distribution of the above cathode material powder, and the above D max is the maximum particle size in the volume cumulative particle size distribution of the above cathode material powder.

[0066]

[0067] The lithium nickel oxide particles in the form of single particles, which were previously used as cathode material powder, had the advantage of less particle breakage during rolling, but when driven at high voltage, the particle breakage during rolling was not small enough to sufficiently suppress side reactions with the electrolyte.

[0068] The inventors of the present invention have conducted continuous research to solve such problems and have found that by controlling the PCF value of the cathode powder within a certain range, particle breakage during cathode rolling can be reduced, and the resulting side reaction with the electrolyte can be reduced, thereby improving the continuous charging characteristics, thereby completing the present invention.

[0069] The above PCF value is a combination of the BET specific surface area of ​​the positive electrode powder and the particle size value of the volume cumulative particle size distribution of the positive electrode powder measured using the laser diffraction method. In order to achieve the excellent effects intended by the present invention, an appropriate combination of the BET specific surface area of ​​the positive electrode powder and the particle size value is required.

[0070] Specifically, even if the BET specific surface area of ​​the cathode powder satisfies a certain range, if the particle size values ​​are not adjusted to satisfy the PCF range, particle breakage during rolling cannot be adequately prevented. Conversely, even if the particle size values ​​are within a certain range, if the BET specific surface area of ​​the cathode powder is not adjusted to satisfy the PCF range, particle breakage during rolling cannot be adequately prevented.

[0071] More specifically, the PCF is P0 measured from the volume cumulative particle size distribution of the cathode material powder using laser diffraction. D min , D 50 , D max And the BET specific surface area S of the above cathode material powder BET (Unit: m 2 / g) as parameters, and is expressed as in the above equation (1). The PCF may be 2.0 or more and 3.4 or less, preferably 2.15 or more and 3.35 or less, more preferably 2.4 or more and 3.3 or less, and even more preferably 2.5 or more and 3.2 or less. If the PCF value is less than 2.0, S BETis excessively low, or the above-mentioned volume cumulative particle size distribution is excessively wide from side to side, or the particle size distribution of large particles that are agglomerated with multiple single particles or pseudo-single particles is excessively wide. In this state, there is a high probability that large particles that are agglomerated with multiple single particles or pseudo-single particles will be broken by rolling, and thus, the side reaction between the positive electrode active material and the electrolyte increases during continuous charging. If the PCF value exceeds 3.4, S BET is excessively high, or the above-mentioned volume cumulative particle size distribution is excessively narrow from side to side, or the particle size distribution of small particles in the form of single particles or pseudo-single particles is excessively wide. In this state, the friction between particles is intensified during electrode rolling, so the rolling characteristics are deteriorated, and particle breakage due to rolling is intensified. In particular, even if a coating layer is formed for the purpose of suppressing side reactions with the electrolyte and stabilizing the surface of the positive electrode active material, if particle breakage occurs, a problem occurs in which a newly unstable surface is formed. If a newly unstable surface is formed as described above, the side reaction between the positive electrode active material and the electrolyte increases, and there is a problem in that the lifespan and continuous charging characteristics of the battery are deteriorated. Therefore, when the PCF satisfies the above range, the breakage of particles of 1 μm or less during electrode rolling is reduced, the side reaction with the electrolyte is reduced, and the lifespan characteristics and continuous charging characteristics are improved.

[0072]

[0073] Meanwhile, the BET specific surface area value and particle size value of the positive electrode powder satisfying the aforementioned PCF range can be controlled by various methods, but preferably, they can be implemented by controlling the content of Ni included in the lithium nickel-based oxide particles, the composition of the lithium nickel-based oxide particles, the temperature and time conditions during firing of the precursor for the positive electrode active material and the lithium source, the firing temperature and time during formation of the coating layer formed on the positive electrode active material, the grinding conditions of the positive electrode powder, etc.

[0074]

[0075] In addition, the positive electrode active material particle of the present invention may be a single particle composed of one nodule and / or a quasi-single particle which is a composite of 30 or fewer, preferably 2 to 20, and more preferably 2 to 10 nodules, or may be in a form including them. Preferably, the positive electrode powder according to the present invention may be composed of a combination of positive electrode active material particles in the form of single particles and quasi-single particles. When the number of nodules constituting the positive electrode active material particle exceeds 30, particle breakage increases during electrode manufacturing, and the occurrence of internal cracks due to volume expansion / contraction of the nodules during charge / discharge increases, which may deteriorate the effect of improving high-temperature life characteristics and high-temperature storage characteristics.

[0076]

[0077] Meanwhile, the lithium nickel-based oxide particles may have a composition represented by the following [chemical formula 1].

[0078] [Chemical Formula 1]

[0079] Li a Ni b Co c Mn d M 1 e O2

[0080] In the above chemical formula 1, M 1 is at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.8≤a≤1.2, 0.5≤b≤0.8, 0 <c≤0.3, 0<d≤0.3, 0≤e≤0.2일 수 있다. 리튬의 몰비가 상기 범위를 만족할 때, 안정적인 층상 결정 구조가 형성될 수 있다.

[0081] The above a represents the molar ratio of lithium in the lithium composite transition metal oxide particles, and may be 0.8≤a≤1.2, 0.9≤a≤1.1, or 0.95≤a≤1.10. When the molar ratio of lithium satisfies the above range, a stable layered crystal structure can be formed.

[0082] The above b represents the molar ratio of nickel among the total metals excluding lithium in the lithium composite transition metal oxide particles, and may be 0.5≤b≤0.8, 0.50≤b≤0.75, 0.55≤b≤0.70, or 0.55≤b≤0.65. Since a higher content of nickel among the transition metals enables a higher capacity to be realized, a nickel content of 0.5 or more is more advantageous for realizing high capacity.

[0083] The above c represents the molar ratio of cobalt among all metals excluding lithium in the lithium nickel oxide, and is 0. <c≤0.3, 0<c≤0.25, 0<c≤0.2, 0<c≤0.15 또는 0<c≤0.1일 수 있다. 코발트의 몰비가 상기 범위를 만족할 때, 양호한 저항 특성 및 출력 특성을 구현할 수 있다.

[0084] The above d represents the molar ratio of manganese among all metals excluding lithium in the lithium nickel oxide, and is 0. <d≤0.4, 0.1≤d≤0.4, 0.15≤d≤0.4 또는 0.2<d≤0.4일 수 있다. 망간의 몰비가 상기 범위를 만족할 때, 양극 활물질의 구조 안정성이 우수하게 나타날 수 있다.

[0085] The above e is M of all metals except lithium in lithium nickel oxide. 1 Indicates the molar ratio of elements, and the above M 1 is a doping element substituted at the transition metal site, and may be 0≤e≤0.20, 0≤e≤0.15, or 0≤e≤0.10. M 1 When included in an appropriate amount, it can play a role in promoting particle growth during firing or improving crystal structure stability.

[0086]

[0087] Meanwhile, the above cathode material powder has a BET specific surface area of ​​0.2 m 2 / g or more than 1.3m 2 / g or less, preferably 0.3m 2 / g or more than 1.0m 2 / g or less, more preferably 0.4m 2 / g or more than 0.9m 2 / g or less, more preferably 0.5m 2 / g or more than 0.85m 2 / g or less. When the above cathode material powder satisfies the above BET specific surface area range, the rolling characteristics of the electrode can be improved, and particle breakage can be reduced, thereby suppressing side reactions with the electrolyte.

[0088]

[0089] Meanwhile, the above P0 is the intensity of the maximum peak (vol%) in the volume cumulative particle size distribution measured using a laser diffraction method for the above cathode material powder, and the above P0 may be 8 or more, preferably 9 or more, and more preferably 10 or more. When the above P0 satisfies the above range, it can have an appropriate volume cumulative particle size distribution shape, so that particle breakage is reduced and an appropriate electrode density can be achieved.

[0090]

[0091] Meanwhile, the above D 50 is the average particle diameter in the volume cumulative particle size distribution measured using laser diffraction method for the above cathode material powder, and the above D 50 The thickness may be 1 ㎛ or more and 10 ㎛ or less, preferably 2 ㎛ or more and 8 ㎛ or less, more preferably 3 ㎛ or more and 7 ㎛ or less, and even more preferably 3 ㎛ or more and 5 ㎛ or less. When the above range is satisfied, the processability during electrode manufacturing may be excellent, the electrolyte impregnation property may be increased, the electrochemical properties may be increased, and the resistance may be reduced and the output characteristics may be improved.

[0092]

[0093] Meanwhile, the above D min is the minimum particle size in the volume cumulative particle size distribution measured using laser diffraction for the above cathode material powder, and the above D min The D may be 0.75㎛ or more and 2.0㎛ or less, preferably 0.8㎛ or more and 1.5㎛ or less, more preferably 0.9㎛ or more and 1.4㎛ or less. min When this above range is satisfied, the friction between particles is not large, so the rolling characteristics can be excellent, the gaps between large particles can be effectively filled by small particles, so the electrode density can be excellent, and the particle breakage can be reduced, so that the side reaction between the positive electrode active material and the electrolyte can be reduced.

[0094]

[0095] Meanwhile, the above D max is the maximum particle diameter in the volume cumulative particle size distribution measured using laser diffraction of the above cathode material powder, and the above D max may be 8㎛ or more and 18㎛ or less, preferably 9㎛ or more and 16㎛ or less, more preferably 10㎛ or more and 14㎛ or less. The above D max When the above range is satisfied, an appropriate volumetric cumulative particle size distribution graph can be formed, and the gaps between large particles can be effectively filled by small particles during electrode rolling, so that the electrode density can be excellent, and particle breakage can be reduced, so that side reactions between the positive electrode active material and the electrolyte can be reduced.

[0096]

[0097] Meanwhile, the above cathode material powder may have an SP value expressed by the following formula (2) of 0.20 or more and 0.33 or less.

[0098] Equation (2):

[0099]

[0100] The SP value represented by the above formula (2) may preferably be 0.23 or more and 0.33 or less, more preferably 2.5 or more and 0.32 or less. When the SP value represented by the above formula (2) satisfies the above range, an appropriate volume cumulative particle size distribution graph can be formed, so that particle breakage is reduced, and side reactions with the electrolyte at high voltage can be reduced.

[0101]

[0102] Meanwhile, the positive electrode powder may have a fine particle generation rate of 1 μm or less in particle size when the positive electrode powder is pressurized at 9 tons, preferably 2.8 μm or less in particle size, more preferably 2.5 μm or less in particle size, and even more preferably 2 μm or less in particle size. Since the surface side reaction of the positive electrode active material is mainly caused by the generation of fine particles of the positive electrode active material, if a large amount of fine particles of 1 μm or less in particle size are generated, the side reaction with the electrolyte may become severe, which may have a negative effect on the life characteristics and continuous charging characteristics.

[0103]

[0104] anode

[0105] Next, the anode according to the present invention will be described.

[0106] The positive electrode according to the present invention comprises the positive electrode material powder of the present invention described above. Specifically, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer comprises the positive electrode material powder of the present invention. Since the positive electrode material powder has been described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0107]

[0108] The positive electrode current collector may include a highly conductive metal, and is not particularly limited as long as it is easily adhered to by the positive electrode active material layer and does not react within the voltage range of the battery. The positive electrode current collector may be made of, for example, stainless steel, aluminum, nickel, titanium, heat-treated carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. In addition, the positive electrode current collector may typically have a thickness of 3 μm to 500 μm, and fine unevenness may be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0109]

[0110] The above positive electrode active material layer may optionally include a conductive material and a binder, together with the positive electrode material powder, as needed.

[0111] At this time, the positive electrode material powder may be included in an amount of 80% to 99% by weight, more specifically 90% to 98% by weight, based on the total weight of the positive electrode active material layer.

[0112]

[0113] The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any particular limitation. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. The conductive material may be included in an amount of 0.01 wt% to 10 wt%, preferably 0.1 wt% to 9 wt%, and more preferably 0.1 wt% to 5 wt%, based on the total weight of the positive electrode active material layer.

[0114]

[0115] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylalcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and polymers in which hydrogens of these are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The above binder may be included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%, based on the total weight of the positive electrode active material layer.

[0116]

[0117] The above-described positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode material powder described above is used. Specifically, the positive electrode slurry composition, prepared by dissolving or dispersing the above-described positive electrode material powder and optionally a binder, a conductive agent, and a dispersant in a solvent as needed, is applied onto a positive electrode current collector, followed by drying and rolling.

[0118] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethyl formamide (DMF), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0119]

[0120] Alternatively, the positive electrode may be manufactured by casting the positive electrode slurry composition onto a separate support, peeling the resulting film from the support, and laminating the resulting film onto a positive electrode current collector.

[0121]

[0122] lithium secondary battery

[0123] Next, a lithium secondary battery according to the present invention will be described.

[0124]

[0125] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and electrolyte interposed between the positive electrode and the negative electrode. Since the positive electrode is the same as described above, a detailed description thereof will be omitted, and only the remaining components will be specifically described below.

[0126] In addition, the lithium secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0127]

[0128] In the above lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0129] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0130]

[0131] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0132] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β(0 < β < 2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fibers, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature heat-treated carbon such as petroleum or coal tar pitch derived cokes.

[0133] The above negative electrode active material may be included in an amount of 80 wt% to 99 wt%, 82 wt% to 99 wt%, or 84 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0134]

[0135] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and is typically added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0136]

[0137] The conductive agent is a component for further improving the conductivity of the negative electrode active material, and may be included in an amount of 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0138]

[0139] The above negative electrode active material layer can be manufactured by applying and drying a negative electrode slurry composition prepared by dissolving or dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, on a negative electrode current collector, or by casting the negative electrode slurry composition on a separate support, and then laminating the obtained film by peeling it off from the support on a negative electrode current collector.

[0140]

[0141] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without special restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0142]

[0143] In addition, the electrolyte used in the present invention may include, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0144] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0145] The organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R represents a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.

[0146]

[0147] The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in a lithium secondary battery. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - At least one selected from the group consisting of, and the lithium salt is LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2) 2. LiCl, LiI, or LiB(C2O4)2 can be used. The concentration of the lithium salt is preferably within the range of 0.1M to 4.0M, preferably 0.5M to 3.0M, and more preferably 1.0M to 2.0M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0148]

[0149] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 to 10.0 wt% based on the total weight of the electrolyte.

[0150]

[0151] Since the lithium secondary battery according to the present invention as described above has excellent stability and electrochemical performance even at high voltages, the end-of-charge voltage during operation can be 4.35 V or higher, and when operated at such a high operating voltage, it can implement superior high-capacity characteristics compared to conventional lithium secondary batteries. The operating voltage of the lithium secondary battery according to the present invention can be 2.0 V to 4.5 V, preferably 2.0 V to 4.0 V.

[0152]

[0153] In addition, since the lithium secondary battery according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it is useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0154] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0155] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0156]

[0157] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0158]

[0159] Hereinafter, the present invention will be described in more detail through specific examples.

[0160]

[0161] Example 1

[0162] Precursor manufacturing

[0163] After adding 4 L of distilled water to a co-precipitation reactor (capacity 20 L), maintaining the temperature at 50°C under a nitrogen atmosphere, 100 mL of a 28 wt% ammonia aqueous solution was added, and then a 3.2 mol / L transition metal solution containing NiSO4, CoSO4, and MnSO4 mixed in a molar ratio of nickel: cobalt: manganese of 0.6:0.1:0.3 was continuously added to the reactor at a rate of 30 mL / hr, and a 28 wt% ammonia aqueous solution was continuously added at a rate of 42 mL / hr. The mixture was stirred at an impeller speed of 400 rpm, and a 40 wt% sodium hydroxide solution was added so as to maintain the pH of the reaction solution at 9.0, thereby performing a co-precipitation reaction for 24 hours to form precursor particles.

[0164] The precursor particles were separated and washed, and then dried in an oven at 130°C to prepare a precursor.

[0165]

[0166] <Manufacturing of positive electrode powder>

[0167] The precursor for the positive electrode active material, LiOH, manufactured as described above was mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.05, and then calcined at 940°C for 20 hours to manufacture positive electrode powder.

[0168] After that, the cathode material powder was crushed once using a jaw crusher at a rotation speed of 200 rpm, and then crushed once in a jet mill under the conditions of a gas pressure of 10 bar and a gas velocity of 350 m / s, and dry-pulverized to a size of 4 μm. The composition of the manufactured cathode material powder was Li[Ni 0.6 Co 0.1 Mn 0.3 ]O2).

[0169] Afterwards, the cathode material powder, Al2O3, and WO3 were mixed so that the molar ratio of the cathode material powder: Al: W was 100:0.3:0.1, and then calcined at 450°C for 5 hours to manufacture cathode material powder having Al and W coating layers formed thereon.

[0170]

[0171] Example 2

[0172] A cathode material powder was manufactured in the same manner as in Example 1, except that the cathode material powder, Al2O3, and WO3 were mixed and then fired at 550°C for 5 hours to form a coating layer.

[0173]

[0174] Example 3

[0175] A cathode material powder was manufactured in the same manner as in Example 1, except that the precursor for the cathode active material was mixed with LiOH and then calcined at 930°C for 20 hours.

[0176]

[0177] Comparative Example 1

[0178] A cathode material powder was manufactured in the same manner as in Example 1, except that the cathode material powder was crushed once using a jaw crusher at a rotation speed of 200 rpm and then crushed three times using a pin mill at a rotation speed of 10,000 rpm.

[0179]

[0180] Comparative Example 2

[0181] After mixing the precursor for the positive electrode active material and LiOH, the mixture was calcined at 930°C for 20 hours to produce positive electrode powder, and then the positive electrode powder was crushed once using a jaw crusher at a rotation speed of 200 rpm and then crushed three times using a pin mill at a rotation speed of 10,000 rpm, and the positive electrode powder was produced in the same manner as in Example 1, except that the positive electrode powder was crushed three times using a pin mill at a rotation speed of 10,000 rpm.

[0182]

[0183] Comparative Example 3

[0184] A cathode material powder was manufactured in the same manner as in Example 1, except that the cathode material powder was crushed once using a jaw crusher at a rotation speed of 200 rpm and then crushed four times using a pin mill at a rotation speed of 10,000 rpm.

[0185]

[0186] Comparative Example 4

[0187] After mixing the precursor for the positive electrode active material and LiOH, the mixture was calcined at 930°C for 20 hours to produce positive electrode powder, and then the positive electrode powder was crushed once using a jaw crusher at a rotation speed of 200 rpm, and then crushed four times using a pin mill at a rotation speed of 10,000 rpm, and the positive electrode powder was produced in the same manner as in Example 1, except that the positive electrode powder was crushed four times using a pin mill at a rotation speed of 10,000 rpm.

[0188]

[0189] Experimental Example 1: Measurement of volume-cumulative particle size distribution and BET specific surface area

[0190] The volume cumulative particle size distribution (PSD) of the cathode material powders manufactured according to Examples 1 to 3 and Comparative Examples 1 to 4 was measured, and P0, D according to the volume cumulative particle size distribution min , D 50 , D max It is shown in [Table 1] below.

[0191] In addition, 3 g of the cathode material powder manufactured according to Examples 1 to 3 and Comparative Examples 1 to 4 was collected and measured using the BET method using BELSORP-mini II, and the measurement results are shown in [Table 1] below.

[0192] Additionally, the PCF values ​​obtained using the above-described method are shown in [Table 1] below.

[0193]

[0194] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 P0 (vol%) 10.03 11.17 12.19 8.09 6.58 11.52 12.48 D 50 (㎛)3.914.093.533.83.373.823.65D min (㎛)0.9721.3751.3750.70.4860.680.68D max (㎛)13.0813.081114.518.513.0813.08BET (m 2 / g)0.860.650.850.80.880.881.01PCF2.762.192.991.881.103.443.97

[0195] Experimental Example 2: Measurement of particle breakage

[0196] 5 g of the cathode powders manufactured according to Examples 1 to 3 and Comparative Examples 1 to 4 were placed in a cylindrical metal mold with a diameter of 1.2 cm and pressed under a pressure of 9 tons. The volumetric cumulative particle size distribution (PSD) was measured to determine the rate of generation of fine particles with a particle size of 1 μm or less. The particle size distribution was measured using Microtrac's S-3500, and the rate of generation of fine particles with a particle size of 1 μm or less was converted into volume% with respect to the total weight of the cathode powder. Among the measured volumetric cumulative particle size distributions (PSD), the graphs of the volumetric cumulative particle size distributions before and after the 9-ton pressure press for Example 1 and Comparative Example 2 are shown in FIGS. 1 and 2, respectively, and the rate of generation of fine particles with a particle size of 1 μm or less for Examples 1 to 3 and Comparative Examples 1 to 4 is shown in [Table 2].

[0197] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 41㎛ or less fine particle generation rate (volume %) 1.86 2.79 0.07 3.85 8.63 4.54 3.33

[0198] Through the above [Table 2], it can be confirmed that in the case of the cathode material powders of Examples 1 to 3, whose PCF values ​​satisfy the range of the present invention, the amount of fine powder generated when pressing at a pressure of 9 tons is significantly less than that of the cathode material powders manufactured by Comparative Examples 1 to 4.

[0199] Experimental Example 3: Evaluation of Continuous Charging Characteristics

[0200] The cathode material powders of Examples 1 to 3 and Comparative Examples 1 to 4, respectively, the conductive material (carbon black), and the binder (PVDF) were mixed in N-methylpyrrolidone at a weight ratio of 95:2:3 to prepare cathode slurries containing the cathode material powders of Examples 1 to 3 and Comparative Examples 1 to 4, respectively. The cathode slurry was applied to one surface of an aluminum current collector, dried at 60°C, and then rolled to prepare a cathode.

[0201] Lithium metal was used as the cathode.

[0202] An electrode assembly was manufactured by interposing a porous polyethylene separator between the positive and negative electrodes, and the electrode assembly was placed inside a battery case, and an electrolyte was injected into the case to manufacture a half-cell. The electrolyte was manufactured by dissolving 1.0 M LiPF6 in a mixed organic solvent containing ethylene carbonate / ethyl methyl carbonate / diethyl carbonate in a volume ratio of 3:4:3.

[0203] For each half-cell battery manufactured above, after charging to a high voltage of 4.8 V at a constant current of 0.1 C at 60°C, the current was measured after the constant voltage was applied. The measurement results are disclosed in Fig. 3. In addition, among the graphs of Fig. 3, only the current is shown in Fig. 4, and only the voltage is shown in Fig. 5.

[0204]

[0205] In the case of half-cell batteries using the positive electrode powders of Examples 1 to 3, particle breakage is reduced compared to the half-cell batteries using the positive electrode powders of Comparative Examples, so that side reactions between the positive electrode active material and the electrolyte are reduced, and as a result, the leakage current during continuous charging is reduced, so that the continuous charging results are excellent, as can be confirmed in FIGS. 3 and 4.

Claims

1. A cathode material powder comprising a cathode active material including lithium nickel oxide particles having a Ni content of 50 mol% to 80 mol% among all metals excluding lithium, The above lithium nickel-based oxide particles are in the form of single particles consisting of one single nodule or pseudo-single particles consisting of a composite of 30 or fewer nodules, A cathode powder having a PCF value of 2.0 or more and 3.4 or less, as expressed by the following equation (1): Equation (1): In the above equation (1), the S BET is the BET specific surface area of ​​the above cathode material powder (unit: m 2 / g), and The above P0 is the intensity of the maximum peak (vol%) in the volume cumulative particle size distribution measured using laser diffraction of the above cathode material powder. Above D 50 is the particle size when the volume accumulation amount is 50% in the volume accumulation particle size distribution of the above cathode material powder, Above D min is the minimum particle size in the volume cumulative particle size distribution of the above cathode material powder, Above D max is the maximum particle size in the volume cumulative particle size distribution of the above cathode material powder.

2. In paragraph 1, The above lithium nickel oxide particles are cathode material powders represented by the following [chemical formula 1]: [Chemical Formula 1] Li a Ni b Co c Mr d M 1 e O2 In the above chemical formula 1, M 1 is at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.8≤a≤1.2, 0.5≤b≤0.8, 0 <c≤0.3, 0<d≤0.4, 0≤e≤0.2임.

3. In paragraph 1, The above cathode material powder has a BET specific surface area of ​​0.2 m 2 / g or more than 1.3m 2 / g or less cathode material powder.

4. In paragraph 1, A cathode material powder having the above P0 of 8 or more.

5. In paragraph 1, Above D 50 This cathode material powder is 1㎛ or more and 10㎛ or less.

6. In paragraph 1, Above D min This cathode material powder is 0.75㎛ or more and 2.0㎛ or less.

7. In paragraph 1, Above D max This cathode material powder is 8㎛ or more and 18㎛ or less.

8. In paragraph 1, A cathode material powder having an SP value of 0.20 or more and 0.33 or less, as expressed by the following formula (2). Equation (2):

9. In paragraph 1, A cathode material powder having a PCF value of 2.5 or more and 3.2 or less.

10. In paragraph 1, A cathode material powder having a particle size of 1㎛ or less of which is generated at a rate of 3% by volume or less when the cathode material powder is pressurized at 9 tons.

11. A cathode comprising the cathode material powder of claim 1.

12. The positive electrode of claim 11; cathode; A separator interposed between the positive and negative electrodes; and A lithium secondary battery containing an electrolyte.

13. In paragraph 12, The above lithium secondary battery has a charging end voltage when operated. Lithium secondary battery with a voltage of 4.35 V or higher.

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