Positive electrode active material, positive electrode active material manufacturing method, positive electrode, and lithium secondary battery

Abstract

The present invention relates to a positive electrode active material and a manufacturing method therefor, the positive electrode active material comprising: a lithium nickel-based oxide; and a coating layer formed on the lithium nickel-based oxide and comprising a compound represented by [chemical formula 2] below. [Chemical formula 2] LixMnyM4 zOw. In [chemical formula 2], M4 is Al or Mo, x is an integer from 2 to 8, y is an integer from 2 to 8, z is an integer from 1 to 12, and w is an integer from 8 to 48.

Description

Cathode active material, method for producing a cathode active material, cathode and lithium secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0092696, filed July 12, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a positive electrode active material, a method for producing the positive electrode active material, a positive electrode including the positive electrode active material, and a lithium secondary battery, and more particularly, to a positive electrode active material having excellent low-temperature output characteristics, a method for producing the same, and a positive electrode including the positive electrode active material and a lithium secondary battery.

[0005]

[0006] Lithium secondary batteries are generally manufactured by forming an electrode assembly by interposing a separator between a positive electrode including a positive electrode active material made of a transition metal oxide containing lithium and a negative electrode including a negative electrode active material capable of storing lithium ions, inserting the electrode assembly into a battery case, injecting a non-aqueous electrolyte that serves as a medium for transferring lithium ions, and then sealing the electrode assembly.

[0007] These lithium secondary batteries are used not only in portable electronic devices like mobile phones and laptops, but also in electric vehicles. Demand for these batteries has been rapidly increasing recently with the expansion of electric vehicles. Lithium secondary batteries used in electric vehicles require high energy density, high output, and durability to withstand harsh environments such as low and high temperatures for extended periods of time.

[0008] However, lithium secondary batteries developed for electric vehicles to date have limitations in performance during winter or in cold regions. This is due to reduced lithium ion mobility in low-temperature environments, which increases resistance and sharply reduces capacity and output. Therefore, there is a pressing need for lithium secondary batteries with superior low-temperature output characteristics.

[0009]

[0010] The present invention is intended to solve the above problems, and to provide a cathode active material having excellent lithium ion mobility and a small increase in resistance even at low temperatures by forming a coating layer having a low lithium migration barrier energy on the surface of a lithium nickel-based oxide, and a method for manufacturing the same.

[0011] In addition, the present invention seeks to provide a positive electrode having excellent low-temperature output characteristics, including the positive electrode active material as described above, and a lithium secondary battery including the same.

[0012]

[0013] [1] The present invention provides a positive electrode active material comprising a lithium nickel-based oxide; and a coating layer formed on the lithium nickel-based oxide and including a compound represented by the following [chemical formula 2].

[0014] [Chemical Formula 2]

[0015] Li x Mn y M 4 z O w

[0016] In the above [chemical formula 2], the above M 4 is Al or Mo, x is an integer from 2 to 8, y is an integer from 2 to 8, z is an integer from 1 to 12, and w is an integer from 8 to 48.

[0017] [2] In the present invention, in the above [1], the compound represented by the above [chemical formula 2] is Li2Mn3AlO8 or Li8Mn8Mo 12 O 48In, it provides a positive electrode active material.

[0018] [3] The present invention provides a positive electrode active material, wherein, in the above [1] or [2], the compound represented by the above [chemical formula 2] is included in an amount of 100 ppm to 20,000 ppm based on the total weight of the positive electrode active material.

[0019] [4] The present invention provides a positive electrode active material, wherein in at least one of the above [1] to [3], the lithium nickel-based oxide is represented by the following [chemical formula 1].

[0020] [Chemical Formula 1]

[0021] Li a Ni b Co c M 1 d M 2 e O2

[0022] In the above [chemical formula 1], M 1 is Mn, Al or a combination thereof, and M 2 Contains at least one element selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.9≤a≤1.1, 0.5≤b<1, 0 <c<0.5, 0<d<0.5, 0≤e≤0.2이다.

[0023] [5] The present invention provides a positive electrode active material, wherein in at least one of the above [1] to [4], the lithium nickel-based oxide is a single-particle lithium nickel-based oxide containing 50 or fewer nodules.

[0024] [6] The present invention provides a positive electrode active material, wherein, in at least one of the above [1] to [5], the Ni content among the total metals excluding lithium of the lithium nickel-based oxide is 50 mol% to 80 mol%.

[0025] [7] The present invention provides a positive electrode active material, wherein in at least one of the above [1] to [6], the lithium nickel-based oxide is represented by the following [chemical formula 1-1].

[0026] [Chemical Formula 1-1]

[0027] Li a1 [Ni b1 Co c1 Mn d1 M 3 e1 ]O2

[0028] In the above [chemical formula 1-1], M 3 It contains at least one element selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.9≤a1≤1.1, 0.5≤b1≤0.8, 0 <c1<0.5, 0<d1<0.5, 0≤e1≤0.2이다.

[0029] [8] The present invention comprises a Li-containing material, a Mn-containing material and an M 4 Containing substance (here, M 4 The present invention provides a method for manufacturing a cathode active material, comprising the steps of preparing a coating raw material by mixing Al or Mo; and the steps of mixing the coating raw material and lithium nickel-based oxide and performing heat treatment to form a coating layer including a compound represented by the above-described [chemical formula 2] on the lithium nickel-based oxide.

[0030] [9] The present invention provides a method for manufacturing a positive electrode active material, wherein, in the above [8], the Li-containing material includes CH3COOLi, LiNO3, LiH3C2O2, LiOH, Li2CO3 or a combination thereof.

[0031]

[0010] In the present invention, in the above [8] or [9], the Mn-containing material (A method for manufacturing a cathode active material is provided, which comprises CH3COO)2Mn, MnCO3, MnO, MnO2, Mn2O3, Mn3O4, MnH6C4O4 or a combination thereof.

[0032]

[0011] The present invention, in at least one of the above [8] to

[0010] , the M 4 Containing materials are Al2O3, AlN, Al(NO3)3, MoO3, (NH4)6Mo7O 24 Or a method for manufacturing a positive electrode active material comprising a combination thereof is provided.

[0033]

[0012] The present invention provides a method for producing a positive electrode active material, wherein, in at least one of the above [8] to

[0011] , the coating raw material and lithium nickel oxide are mixed by a dry or wet method.

[0034]

[0013] The present invention provides a method for producing a positive electrode active material, wherein, in at least one of the above [8] to

[0012] , the heat treatment is performed at 100°C to 1000°C for 1 hour to 12 hours.

[0035]

[0014] In the present invention, in at least one of the above [8] to

[0013] , the step of preparing the coating raw material comprises: a Li-containing material, a Mn-containing material, and an M 4 Containing substance (here, M 4 The present invention provides a method for manufacturing a positive electrode active material, comprising: a step of forming a mixture by mixing Al or Mo; and a step of pre-heat treating the mixture to form a coating raw material.

[0036]

[0015] The present invention provides a method for manufacturing a positive electrode active material, wherein, in the above

[0014] , the pre-heat treatment is performed at 100°C to 1000°C for 3 to 20 hours.

[0037]

[0016] The present invention provides a positive electrode comprising a positive electrode active material according to any one of the above [1] to [7].

[0038]

[0017] The present invention provides a lithium secondary battery comprising a positive electrode according to the above

[0016] ; a negative electrode disposed opposite the positive electrode; and an electrolyte.

[0039]

[0040] The cathode active material according to the present invention includes a coating layer containing a compound represented by [chemical formula 2] on the surface of a lithium nickel-based oxide. Since the compound represented by [chemical formula 2] has a low migration barrier energy for lithium ions, when a coating layer containing the compound is formed on the surface of the cathode active material, the surface resistance of the cathode active material particles decreases and lithium ion diffusivity increases. Therefore, when the cathode active material according to the present invention is applied, the output characteristics of a lithium secondary battery, particularly, low-temperature output characteristics, can be improved.

[0041]

[0042] Figure 1 is a graph showing the results of X-ray diffraction analysis of the coating raw material manufactured in Example 1.

[0043] Figure 2 is a graph showing the results of X-ray diffraction analysis of the coating raw material manufactured in Example 2.

[0044]

[0045] Hereinafter, the present invention will be described in more detail.

[0046] 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 idea 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 way.

[0047] In the present invention, "single-particle type" refers to a particle formed by an aggregation of 50 or fewer sub-particles. The sub-particle unit constituting a single-particle type particle is referred to as a nodule. Single-particle type particles include single particles composed of one nodule and pseudo-single particles that are composites of 2 to 50 nodules.

[0048] The above “nodule” is a sub-particle unit that constitutes a single particle and a pseudo-single particle, and may be a single crystal without a crystalline grain boundary, or a polycrystal that has no apparent grain boundary when observed under a magnification of 5,000 to 20,000 times using a scanning electron microscope.

[0049] In the present invention, a "secondary particle" refers to a particle formed by an aggregation of more than 50 sub-particles. To distinguish it from the sub-particles that constitute a single particle, the sub-particles that constitute a secondary particle are referred to as "primary particles."

[0050] In the present invention, “particle” is a concept including any one or all of a single particle, a pseudo-single particle, a primary particle, a nodule, and a secondary particle.

[0051] In the present invention, the average particle diameter (D) of the nodules or primary particles mean ) means the arithmetic mean value calculated after measuring the particle size of nodules or primary particles observed in scanning electron microscope images.

[0052] In the present invention, "average particle diameter D 50"It refers to the particle size corresponding to 50% of the volume accumulation amount of the volume accumulation particle size distribution of the powder to be measured, and can be measured using the laser diffraction method. For example, after dispersing the powder to be measured in a dispersion medium, it can be measured by 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, obtaining a volume accumulation particle size distribution graph, and then calculating the particle size corresponding to 50% of the volume accumulation amount.

[0053]

[0054] The inventors of the present invention have conducted repeated research to improve the low-temperature output characteristics of lithium secondary batteries and have found that when a cathode active material is applied in which a lithium manganese oxide containing Al or Mo having a low lithium migration barrier energy is coated on the surface of a lithium nickel oxide, the low-temperature output characteristics of a lithium secondary battery can be improved, thereby completing the present invention.

[0055]

[0056] positive electrode active material

[0057] First, the positive electrode active material according to the present invention will be described.

[0058] The cathode active material according to the present invention comprises a lithium nickel-based oxide; and a coating layer formed on the lithium nickel-based oxide and containing a compound represented by the following [chemical formula 2].

[0059] [Chemical Formula 2]

[0060] Li x Mn y M 4 z O w

[0061] In the above [chemical formula 2], the above M 4is Al or Mo, x is an integer from 2 to 8, y is an integer from 2 to 8, z is an integer from 1 to 12, and w is an integer from 8 to 48.

[0062]

[0063] (1) Lithium nickel oxide

[0064] In the cathode active material according to the present invention, the lithium nickel-based oxide may be a lithium composite transition metal oxide containing nickel in an amount of 50 mol% or more, 50 mol% to 80 mol%, 50 mol% to 70 mol%, or 55 mol% to 65 mol% of the total metal excluding lithium.

[0065] For example, the lithium nickel-based oxide may be represented by the following [chemical formula 1].

[0066] [Chemical Formula 1]

[0067] Li a Ni b Co c M 1 d M 2 e O2

[0068] In the above [chemical formula 1], M 1 is Mn, Al or a combination thereof, and preferably may be Mn or a combination of Mn and Al.

[0069] In the above [chemical formula 1], the M 2 is a doping element doped into the transition metal site included in the above lithium nickel-based oxide, M 2 When the element is included, effects such as suppression of cation mixing of the positive electrode active material and suppression of structural change during repeated charge and discharge can be obtained. The above M 2It may include one or more elements selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and preferably may include one or more elements selected from the group consisting of Zr, W, Y, Ba, Ti, Mg, Ta, and Nb.

[0070] In the above [Chemical Formula 1], a is the molar ratio of lithium in the lithium nickel-based oxide, and may be 0.9≤a≤1.1, 0.95≤a≤1.1, or 1≤a≤1.08. When a satisfies the above range, excellent capacity characteristics are exhibited, and a stable layered structure can be formed.

[0071] In the above [Chemical Formula 1], b represents the molar ratio of nickel among the total metals excluding lithium in the lithium nickel-based oxide, and may be 0.5≤b<1.0, 0.5≤b≤0.95, 0.5≤b≤0.90, 0.5≤b≤0.80, or 0.5≤b≤0.70. When the above range is satisfied, the capacity characteristics and structural stability may be excellent.

[0072] In the above [chemical formula 1], c represents the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel oxide, and is 0. <c<0.5, 0.01≤c<0.5, 0.02≤c<0.5, 0.03≤c<0.4, 0.05≤c≤0.3, 0.08≤c≤0.2, 또는 0.08≤c≤0.12일 수 있다. 상기 범위를 만족할 경우, 우수한 출력 특성을 가지면서, 상대적으로 M 1 The content can be increased to improve structural stability.

[0073] In the above [chemical formula 1], d is M among all metals excluding lithium in the lithium nickel oxide. 1It represents the molar ratio of 0 <d<0.5, 0.01≤d<0.5, 0.05≤d<0.5, 0.1≤d<0.5, 0.2≤d≤0.4, 또는 0.25≤d≤0.35일 수 있다. 상기 범위를 만족할 경우, 우수한 구조적 안정성을 가질 수 있다.

[0074] In the above [chemical formula 1], e is M among all metals excluding lithium in the lithium nickel oxide. 2 It represents the molar ratio of , and may be 0≤e≤0.2, 0≤e≤0.15, 0≤e≤0.10, 0≤e≤0.05 or 0≤e≤0.01. When the above range is satisfied, the structural stability of the lithium nickel-based oxide can be improved.

[0075] In the above [Chemical Formula 1], d / c may be 1.1 to 5.0, 1.5 to 4.5, 2.0 to 4.0, 2.5 to 3.5, or 2.7 to 3.3. When the above range is satisfied, the structural stability and thermal stability of the positive electrode active material can be improved while having a cost advantage by containing relatively less cobalt. In addition, when combined with the coating layer according to the present invention, the effect of improving low-temperature output characteristics can be maximized.

[0076]

[0077] The form of the lithium nickel-based oxide is not particularly limited, and may be in the form of secondary particles in which more than 50 primary particles are aggregated, or in the form of single particles containing 50 or fewer nodules. If necessary, a cathode active material including a secondary particle-type lithium nickel-based oxide and a cathode active material including a single particle-type lithium nickel-based oxide may be mixed and used. In the case of a cathode active material including a secondary particle-type lithium nickel-based oxide, the resistance and capacity characteristics are excellent, and in the case of a cathode active material including a single particle-type lithium nickel-based oxide, the high temperature / high voltage stability and life characteristics are excellent. Therefore, a lithium nickel-based oxide of an appropriate form may be selected and used in consideration of the performance and specifications of the lithium secondary battery to be manufactured.

[0078] According to one embodiment, the lithium nickel-based oxide may be a single-particle lithium nickel-based oxide comprising 50 or fewer nodules.

[0079] In the case of single-particle lithium nickel-based oxide, compared to secondary particle lithium nickel-based oxide, there is less particle breakage due to rolling during the production of the positive electrode, and the structural stability is excellent under high temperature and / or high voltage conditions. Therefore, when single-particle lithium nickel-based oxide is applied, there is less positive electrode degradation under high temperature / high voltage conditions, and there is less generation of fine particles after the production of the positive electrode, so there is less gas generation due to side reactions between the fine particles and the electrolyte. Therefore, when single-particle lithium nickel-based oxide is applied, it is advantageous for producing a lithium secondary battery with long life characteristics.

[0080] Meanwhile, it may be preferable that the single-particle lithium nickel-based oxide includes 50 or fewer nodules, preferably 30 or fewer nodules, more preferably 1 to 25 nodules, and even more preferably 1 to 15 nodules. This is because when the single-particle lithium nickel-based oxide includes an excessive number of nodules, particle breakage increases during electrode manufacturing, and internal cracks occur more frequently due to volume expansion / contraction of the nodules during charge / discharge, resulting in poor high-temperature life characteristics and high-temperature storage characteristics.

[0081] Meanwhile, the average particle size of the nodules may be 0.8 µm to 4.0 µm, preferably 0.8 µm to 3 µm, and more preferably 1.0 µm to 3.0 µm. When the average particle size of the nodules satisfies the above range, particle breakage is minimized during electrode manufacturing, and resistance increase can be more effectively suppressed. At this time, the average particle size of the nodules refers to a value obtained by measuring the particle sizes of nodules observed in SEM images obtained by analyzing the positive electrode active material powder with a scanning electron microscope, and then calculating the arithmetic mean of the measured values.

[0082] Meanwhile, the lithium nickel oxide is D 50 It may be 2.0㎛ to 10.0㎛, preferably 2.0㎛ to 8.0㎛. More preferably, it is preferably about 3.0㎛ to 7.0㎛. D of lithium nickel-based oxide 50 If this is too small, the processability during electrode manufacturing may be poor, the electrolyte impregnation may be poor, and the electrochemical properties may increase. 50 If this is too large, there is a problem that the resistance increases and the output characteristics deteriorate.

[0083]

[0084] Meanwhile, the single-particle lithium nickel-based oxide may have a Ni content of 50 mol% to 80 mol%, preferably 50 mol% to 75 mol%, and more preferably 50 mol% to 70 mol%, of the total metal excluding lithium. In the case of the single-particle lithium nickel-based oxide having a nickel content of 50 mol% to 80 mol%, the structural stability at high voltage is higher than that of the lithium nickel-based oxide having a nickel content exceeding 80 mol% or having a secondary particle form, so that the degradation of life characteristics during high voltage operation can be minimized. Specifically, the higher the nickel content in the lithium nickel-based oxide, the more reactive Ni is. +4 As the number of ions increases, the structural stability of the positive electrode active material decreases during charge and discharge, causing positive electrode degradation to occur rapidly. This phenomenon becomes more severe during high voltage operation. Therefore, in the present invention, by applying a lithium nickel-based oxide with a low Ni content of 80 mol% or less, it is possible to suppress the reduction in lifespan due to active material degradation during high voltage operation. However, if the Ni content is too low, the capacity characteristics deteriorate, so the Ni content of the lithium nickel-based oxide is preferably about 50 mol% to 80 mol%.

[0085] Specifically, the single-particle lithium nickel-based oxide may be a lithium transition metal oxide containing nickel, manganese, and cobalt, and may be, for example, represented by the following [Chemical Formula 1-1].

[0086] [Chemical Formula 1-1]

[0087] Li a1 [Ni b1 Co c1 Mn d1 M 3 e1 ]O2

[0088] In the above [chemical formula 1-1], M 2It may contain one or more elements selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo. M 3 When the element is included, the structural stability of lithium nickel-based oxide particles is improved, so that better life characteristics can be realized when driving at high voltage. Preferably, the M 3 The element may include at least one selected from the group consisting of Ti, Mg, Al, Zr and Y, and more preferably, at least two selected from the group consisting of Ti, Mg, Al, Zr and Y.

[0089] The above a1 represents the lithium molar ratio in the lithium nickel-based oxide, and may be 0.9≤a1≤1.1, 0.95≤a1≤1.1, or 1.0≤a1≤1.08. When a1 satisfies the above range, a stable layered crystal structure can be formed.

[0090] The above b1 represents the molar ratio of nickel among the total metals excluding lithium in the lithium nickel-based oxide, and may be 0.5≤b1≤0.8, 0.5≤b1≤0.7, or 0.55≤b1≤0.7. When b1 satisfies the above range, excellent high-temperature and / or high-voltage stability is exhibited.

[0091] The above c1 represents the molar ratio of cobalt among all metals excluding lithium in the lithium nickel oxide, and is 0. <c1<0.5, 0.01≤c1≤0.4, 0.05≤c1≤0.3 또는 0.08≤c1≤0.15일 수 있다.

[0092] The above d1 represents the molar ratio of manganese among all metals excluding lithium in the lithium nickel oxide, and is 0. <d1<0.5, 0.05≤d1≤0.4, 0.1≤d1≤0.4, 0.2≤d1≤0.4, 또는 0.25≤d1≤0.35일 수 있다.

[0093] The above e1 is M of all metals except lithium in lithium nickel oxide.3 It represents the molar ratio of elements, and can be 0≤e1≤0.2, 0≤e1≤0.1, 0≤e1≤0.05, or 0≤e1≤0.01. M 3 When the molar ratio of the elements satisfies the above range, both the structural stability and capacity of the positive electrode active material can be excellent.

[0094]

[0095] (2) Coating layer

[0096]

[0097] The above coating layer is formed on the lithium nickel-based oxide, and is intended to suppress direct contact between the electrolyte and the lithium nickel-based oxide, thereby reducing gas generation during charging and discharging and preventing transition metal elution.

[0098] The coating layer according to the present invention comprises a compound represented by the following [chemical formula 2].

[0099] [Chemical Formula 2]

[0100] Li x Mn y M 4 z O w

[0101] In the above [chemical formula 2], the above M 4 is Al or Mo.

[0102] In the above [chemical formula 2], x is an integer from 2 to 8. Specifically, x may be an integer from 2 to 6, an integer from 2 to 4, an integer from 2 to 3, or 2.

[0103] In the above [chemical formula 2], y is an integer from 2 to 8. Specifically, y may be an integer from 3 to 8, or an integer from 2 to 6, an integer from 2 to 6, an integer from 2 to 4, an integer from 2 to 3, or 2.

[0104] In the above [chemical formula 2], z is an integer from 1 to 12. Specifically, z may be an integer from 1 to 10, an integer from 1 to 8, an integer from 1 to 6, an integer from 1 to 4, or an integer from 1 to 3.

[0105] In the above [chemical formula 2], w is an integer from 8 to 48. Specifically, w may be an integer from 8 to 45, an integer from 8 to 42, an integer from 8 to 36, an integer from 8 to 32, an integer from 8 to 28, an integer from 8 to 24, an integer from 8 to 20, an integer from 8 to 16, or an integer from 8 to 12.

[0106] The compound represented by the above [chemical formula 2] has a low lithium migration barrier energy of 0.4 eV or less and excellent lithium diffusivity. Here, the lithium migration barrier energy refers to the energy required for lithium to diffuse outward from a chemical substance containing lithium. Accordingly, when a coating layer containing the compound of [chemical formula 2] is formed on the surface of a positive electrode active material, the side reaction with the electrolyte can be effectively suppressed while minimizing the decrease in the mobility of lithium ions. In addition, when a coating layer containing the compound of [chemical formula 2] is formed on the surface of a positive electrode active material, the surface resistance of the positive electrode active material is lowered at low temperatures compared to a positive electrode active material on which a coating layer is not formed, so that lithium ions can more easily move out of the positive electrode active material, thereby realizing excellent low-temperature output characteristics.

[0107] Specifically, the compound represented by the above [chemical formula 2] is Li2Mn3AlO8 or Li8Mn8Mo 12 O 48 It may be. In this case, the low-temperature output characteristics may be better.

[0108] In the present invention, the compound represented by [Chemical Formula 2] may be included in an amount of 100 ppm to 20,000 ppm, 1,000 ppm to 18,000 ppm, 5,000 ppm to 15,000 ppm, 8,000 ppm to 12,000 ppm, 9,000 ppm to 11,000 ppm, or 9,500 ppm to 10,500 ppm based on the total weight of the positive electrode active material. When the content of the compound represented by [Chemical Formula 2] satisfies the above range, a balance can be achieved between the capacity characteristics of the positive electrode active material and the effect of improving low-temperature performance.

[0109]

[0110] Method for manufacturing positive electrode active material

[0111] Next, a method for manufacturing a positive electrode active material according to the present invention will be described.

[0112] The method for manufacturing a positive electrode active material according to the present invention comprises: (1) a Li-containing material, a Mn-containing material, and M 4 Containing substance (here, M 4 It includes a step of preparing a coating raw material by mixing (Al or Mo) and (1) a step of mixing the coating raw material and lithium nickel-based oxide and performing heat treatment to form a coating layer including a compound represented by the following [chemical formula 2] on the lithium nickel-based oxide.

[0113] [Chemical Formula 2]

[0114] Li x Mn y M 4 z O w

[0115] In the above [chemical formula 2], the above M 4 is Al or Mo, x is an integer from 2 to 8, y is an integer from 2 to 8, z is an integer from 1 to 12, and w is an integer from 8 to 48.

[0116] Specifically, the compound represented by the above [chemical formula 2] is Li2Mn3AlO8 or Li8Mn8Mo 12 O 48 It could be.

[0117]

[0118] First, Li-containing materials, Mn-containing materials and M 4 A coating raw material is prepared by mixing the containing materials. The coating raw material is for synthesizing a compound represented by the above [chemical formula 2], and includes the Li-containing material, the Mn-containing material, and the M 4 It may be in the form of a mixture of containing substances, and the Li-containing substance, Mn-containing substance and M 4 It may also be a material formed by mixing the containing materials to form a mixture and then pre-heat treating the mixture. When pre-heat treating is performed, the coating raw material may include a compound represented by the above [chemical formula 2].

[0119] The above Li-containing material may include an oxide, nitride, halide, hydroxide, carbonate, nitrate, acetate or a combination thereof containing Li, and may include, for example, CH3COOLi, LiNO3, LiH3C2O2, LiOH, Li2CO3 or a combination thereof, and specifically, may include, but is not limited to, CH3COOLi, LiOH or a combination thereof.

[0120] The above Mn-containing material may include oxides, nitrides, halides, hydroxides, carbonates, nitrates, acetates or combinations thereof containing Mn, for example: ( CH3COO)2Mn, MnCO3, MnO, MnO2, Mn2O3, Mn3O4, MnH6C4O4 or a combination thereof, and specifically, ( CH3COO)2Mn, but is not limited thereto.

[0121] Above M 4 The substance contained is M 4 It may include oxides, nitrides, halides, hydroxides, carbonates, nitrates, ammonium salts or combinations thereof containing elements (Al or Mo), for example, Al2O3, AlN, Al(NO3)3, MoO3, (NH4)6Mo7O 24 or may include a combination thereof, specifically, Al(NO3)3, (NH4)6Mo7O 24 or combinations thereof, but are not limited thereto.

[0122] Meanwhile, the above Li-containing material, Mn-containing material and M 4 When mixing the contained materials, the mixing ratio is Li: Mn: M in the mixture. 4 The molar ratio of the components may be 1.9 to 8.1: 1.9 to 8.1: 0.9 to 12.1, 1.9 to 5.0: 1.9 to 6.0: 0.9 to 10.0, 1.9 to 3.0: 1.9 to 4.0: 0.9 to 5.0, or 1.9 to 2.1: 1.9 to 3.1: 0.9 to 3.1. When the content of each component in the mixture satisfies the above range, it is advantageous for synthesizing the compound represented by [Chemical Formula 2].

[0123] Meanwhile, when performing a pre-heat treatment, the pre-heat treatment can be performed at a temperature of 100°C to 1000°C, 200°C to 900°C, 250°C to 800°C, 300°C to 700°C, or 400°C to 600°C. The pre-heat treatment can be performed for 3 hours to 20 hours, 5 hours to 18 hours, 8 hours to 15 hours, or 10 hours to 14 hours. When the pre-heat treatment is performed under the above conditions, it is advantageous for synthesizing the compound represented by [Chemical Formula 2].

[0124] Specifically, the above M 4When M is Al, the pre-heat treatment may be performed at a temperature of 100°C to 1000°C, 200°C to 950°C, 300°C to 850°C, 400°C to 800°C, 500°C to 700°C, or 550°C to 650°C. 4 When Al, the pre-heat treatment can be performed for 3 to 20 hours, 5 to 18 hours, 8 to 15 hours, or 10 to 14 hours. When the pre-heat treatment is performed under the above conditions, it is represented by [Chemical Formula 2], and the M 4 It is advantageous to synthesize compounds containing Al.

[0125] Specifically, the above M 4 When M is Mo, the pre-heat treatment may be performed at a temperature of 100°C to 1000°C, 150°C to 900°C, 200°C to 800°C, 250°C to 700°C, 280°C to 600°C, 300°C to 500°C, or 350°C to 450°C. 4 When Mo is present, the pre-heat treatment may be performed for 3 to 20 hours, 5 to 18 hours, 8 to 15 hours, or 10 to 14 hours. When the pre-heat treatment is performed under the above conditions, it is represented by [Chemical Formula 2], and the M 4 It is advantageous to synthesize compounds containing Mo.

[0126]

[0127] When the coating raw material is prepared through the above process, the prepared coating raw material and lithium nickel oxide are mixed and heat treated to form a coating layer.

[0128] The mixing method of the above coating raw material and lithium nickel-based oxide is not particularly limited, and may be performed by dry mixing or wet mixing. For example, the solid coating raw material and the solid lithium nickel-based oxide may be mixed dry by placing them in a mixer or the like and stirring them, or the coating raw material and lithium nickel-based oxide may be mixed wet by placing them in a solvent such as water or ethanol and stirring them.

[0129] Meanwhile, the heat treatment may be performed at a temperature of 100°C to 1000°C, 150°C to 900°C, 200°C to 800°C, 250°C to 700°C, 280°C to 600°C, 300°C to 500°C, or 350°C to 450°C. The heat treatment may be performed for 1 hour to 12 hours, 1 hour to 10 hours, 1 hour to 8 hours, 2 hours to 6 hours, or 2 hours to 4 hours. When the heat treatment is performed under the above conditions, a coating layer is smoothly formed on the lithium nickel oxide, and it is advantageous for synthesizing the compound represented by [Chemical Formula 2].

[0130] Since the manufactured positive electrode active material is the same as described above, a detailed description is omitted.

[0131]

[0132] anode

[0133] Next, the positive electrode according to the present invention includes the positive electrode active material described above. Specifically, the positive electrode may include a positive electrode active material layer including the positive electrode active material described above, and more specifically, may include a positive electrode current collector; and a positive electrode active material layer positioned on the positive electrode current collector and including the positive electrode active material described above.

[0134]

[0135] Hereinafter, each component of the anode according to the present invention will be described in detail.

[0136]

[0137] (1) Positive current collector

[0138] As the positive electrode current collector, various positive electrode current collectors used in the relevant technical field can be used. For example, the positive electrode current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The positive electrode current collector may typically have a thickness of 3 to 500 μm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesion of the positive electrode active material. 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.

[0139]

[0140] (2) Positive electrode active material layer

[0141] The positive electrode active material layer may be positioned on the positive electrode current collector, and specifically, may be positioned on one or both sides of the positive electrode current collector. The positive electrode active material layer may have a single layer or a multilayer structure of two or more layers.

[0142] The above positive electrode active material layer may include a positive electrode active material, a positive electrode conductive material, and a positive electrode binder.

[0143] At this time, the positive electrode active material is a positive electrode active material including the positive electrode active material according to the present invention described above, that is, a lithium nickel-based oxide, and a coating layer formed on the lithium nickel-based oxide and including a compound represented by the following [chemical formula 2]; and the specific characteristics of the positive electrode active material are the same as described above.

[0144] [Chemical Formula 2]

[0145] Li x Mn y M 4 z O w

[0146] In the above [chemical formula 2], the above M 4is Al or Mo, x is an integer from 2 to 8, y is an integer from 2 to 8, z is an integer from 1 to 12, and w is an integer from 8 to 48.

[0147] The positive electrode active material may be included in an amount of 90 wt% to 99 wt%, preferably 92 wt% to 98 wt%, and more preferably 94 wt% to 98 wt%, based on the total weight of the positive electrode active material layer. When the above range is satisfied, the energy density and capacity characteristics of a lithium secondary battery to which the positive electrode is applied can be improved.

[0148] The above-mentioned positive electrode 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 special restrictions. 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, carbon fiber, and carbon nanotube; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and 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 positive electrode conductive material may typically be included in an amount of 0.1 to 10 wt%, 0.1 to 8 wt%, or 0.1 to 5 wt% based on the total weight of the positive electrode active material layer.

[0149] The above positive electrode binder serves to improve adhesion between positive electrode particles and adhesion between the positive electrode and the positive electrode current collector, and specific examples thereof include a fluororesin binder including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); a rubber binder including styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; a cellulose binder including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; a polyalcohol binder including polyvinyl alcohol; a polyolefin binder including polyethylene and polypropylene; a polyimide binder; and a polyester binder. And silane binders, etc. can be mentioned, and one of these can be used alone or a mixture of two or more can be used. The positive electrode binder can be included in an amount of 1 to 10 wt%, 0.5 to 10 wt%, or 1 to 8 wt% based on the total weight of the positive electrode active material layer.

[0150]

[0151] The positive electrode can be manufactured by a method known in the art. For example, the positive electrode can be manufactured by mixing a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent in a solvent to manufacture a positive electrode slurry, applying the positive electrode slurry onto a positive electrode current collector, drying, and rolling, or by casting the positive electrode slurry onto a separate support, peeling the support, and laminating the resulting film onto a positive electrode current collector. At this time, as the solvent of the positive electrode slurry, positive electrode slurry solvents generally used in the art can be used, and examples thereof include, but are not limited to, dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, or mixtures thereof. The solvent can be used in an amount that dissolves or disperses the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder, and has a viscosity that allows the negative electrode slurry to be uniformly coated.

[0152]

[0153] lithium secondary battery

[0154] Next, a lithium secondary battery according to the present invention will be described. The lithium secondary battery according to the present invention includes: a positive electrode according to the present invention; an anode positioned opposite the positive electrode; and an electrolyte. Optionally, the lithium secondary battery according to the present invention may further include a separator interposed between the positive electrode and the negative electrode.

[0155] Since the above anode is the same as described above, the remaining components excluding the anode will be described below.

[0156]

[0157] (1) Cathode

[0158] In a lithium secondary battery according to the present invention, the negative electrode includes a negative electrode active material layer including a negative electrode active material, and specifically, may include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.

[0159]

[0160] 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, calcined 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.

[0161]

[0162] The negative electrode active material layer may be positioned on the negative electrode current collector, and specifically, may be positioned on one or both sides of the negative electrode current collector. The negative electrode active material layer may have a single-layer structure or a multi-layer structure of two or more layers.

[0163] When the negative electrode active material layer has a multilayer structure composed of two or more layers, each layer may have different types and / or contents of the negative electrode active material, negative electrode binder, and / or negative electrode conductive material. By forming the negative electrode active material layer into a multilayer structure and varying the composition of each layer, the performance characteristics of the battery, such as rapid charging performance and output characteristics, can be appropriately controlled.

[0164] Meanwhile, a compound capable of reversible intercalation and deintercalation of lithium may be used as the negative electrode active material. 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), metal oxides capable of doping and dedoping lithium, such as SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the above metal 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.

[0165] Meanwhile, both low-crystalline carbon and high-crystalline carbon can 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 amorphous, plate-like, flaky, spherical or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.

[0166] Preferably, the negative electrode active material may be a carbon-based negative electrode active material, and at this time, the carbon-based negative electrode active material may include, for example, natural graphite, artificial graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, or a combination thereof. More preferably, the carbon-based negative electrode active material may include natural graphite and artificial graphite.

[0167] The above carbon-based negative electrode active material has an average particle diameter D 50 It may be 2㎛ to 30㎛, preferably 5㎛ to 30㎛.

[0168] The above negative electrode active material may be included in an amount of 80 wt% to 98 wt%, preferably 90 wt% to 98 wt%, and more preferably 93 wt% to 98 wt%, based on the total weight of the negative electrode active material layer. When the content of the negative electrode active material satisfies the above range, excellent energy density can be achieved.

[0169]

[0170] Meanwhile, the negative electrode active material layer may further include a negative electrode conductive material and / or a negative electrode binder together with the negative electrode active material.

[0171] The negative electrode conductive material is used to provide conductivity to the negative electrode, and can be used without any special restrictions as long as it does not cause a chemical change in the battery to be constructed and has electronic conductivity. Specific examples include carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, and carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and among these, one type alone or a mixture of two or more types may be used.

[0172] The above negative electrode conductive material may typically be included in an amount of 0.1 to 10 wt%, 0.1 to 8 wt%, or 0.1 to 5 wt% based on the total weight of the negative electrode active material layer.

[0173] The above negative electrode binder serves to improve adhesion between negative electrode active material particles and adhesion between the negative electrode active material and the negative electrode current collector. Specific examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof.

[0174] The above negative electrode binder may be included in an amount of 0.1 to 10 wt%, 0.5 to 10 wt%, or 1 to 8 wt% based on the total weight of the negative electrode active material layer.

[0175]

[0176] The above negative electrode can be manufactured by a method known in the art. For example, the negative electrode can be manufactured by mixing a negative electrode active material, a negative electrode binder, and / or a negative electrode conductive material in a solvent to manufacture a negative electrode slurry, applying the negative electrode slurry onto a negative electrode current collector, and then drying and rolling the resulting film, or by casting the negative electrode slurry onto a separate support, and then peeling the resulting film from the support and laminating the resulting film onto a negative electrode current collector.

[0177] Meanwhile, solvents commonly used in the art may be used as the solvent for the negative electrode slurry, and examples thereof include, but are not limited to, dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, or mixtures thereof. The solvent may be used in an amount that dissolves or disperses the negative electrode active material, the negative electrode conductive material, and the negative electrode binder, and provides a viscosity that allows the negative electrode slurry to be uniformly coated.

[0178]

[0179] (2) Electrolyte

[0180] The electrolyte according to the present invention may include a lithium salt and an organic solvent.

[0181] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably within the range of 0.1 to 5.0 M, and preferably 0.1 to 3.0 M. 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.

[0182]

[0183] The above organic solvent may include at least one of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

[0184] The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent, and may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate.

[0185] In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and representative examples thereof include at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and specifically, may include ethylmethyl carbonate (EMC).

[0186] Specific examples of the linear ester organic solvent include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0187] The above cyclic ester organic solvent may include at least one organic solvent selected from the group consisting of butyrolactone, valerolactone, and caprolactone.

[0188] Preferably, the electrolyte according to the present invention may include ethylene carbonate and dimethyl carbonate as organic solvents.

[0189]

[0190] Meanwhile, in addition to the electrolyte components, the electrolyte may additionally include other additives for the purpose of improving the life characteristics of the battery, suppressing battery capacity reduction, and improving the discharge capacity of the battery.

[0191] These other additives may include, as representative examples, at least one other additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds different from the lithium salt included in the electrolyte.

[0192] Specifically, the other additives include vinylene carbonate (VC), vinylethylene carbonate, fluoroethylene carbonate (FEC), 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, 1-methyl-1,3-propene sultone, ethylene sulfate (Esa), trimethylene sulfate (TMS), methyl trimethylene sulfate (MTMS), tetraphenylborate, lithium oxalyldifluoroborate, succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, One or more compounds selected from the group consisting of 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, fluorobenzene, triethanolamine, ethylenediamine, tetravinylsilane, LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide, LiFSI), LiN(SO2CF3)2 (lithium bis(trifluoromethane sulfonyl)imide, LiTFSI), LiPO2F2, LiODFB, LiBOB (lithium bisoxalatoborate (LiB(C2O4)2) and LiBF4) may be mentioned.

[0193] The above-mentioned other additives may be included in an amount of 0.01 to 20 wt% based on the total weight of the electrolyte, and preferably 0.05 to 5.0 wt%. If the content of the above-mentioned other additives is less than 0.01 wt%, the effects of improving the low-temperature output of the battery and the high-temperature storage characteristics and high-temperature life characteristics are minimal, and if the content of the above-mentioned other additives exceeds 20 wt%, there is a possibility that excessive side reactions occur in the electrolyte during charge and discharge of the battery. In particular, when the above-mentioned SEI film forming additives are added in excessive amounts, they may not be sufficiently decomposed at high temperatures and may exist as unreacted substances or precipitated substances in the electrolyte at room temperature. Accordingly, side reactions that reduce the life or resistance characteristics of the secondary battery may occur.

[0194]

[0195] (3) Membrane

[0196] The above separator physically separates the anode and cathode and provides a passage for lithium ions to move. Any separator typically used in lithium secondary batteries may be used without any special restrictions. In this case, the separator may be interposed between the cathode and cathode.

[0197] 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.

[0198]

[0199] The lithium secondary battery according to the present invention as described above can be usefully applied to portable devices such as mobile phones, laptop computers, and digital cameras, as well as electric vehicles such as hybrid electric vehicles (HEVs). Since the lithium secondary battery according to the present invention can realize excellent output characteristics even under low-temperature conditions, it can be particularly usefully used in the electric vehicle field.

[0200] According to another embodiment of the present invention, a battery module including a lithium secondary battery according to the present invention as a unit cell and a battery pack including the same are provided.

[0201] 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 power tools; electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0202]

[0203] Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are intended to enable those skilled in the art to fully understand and easily practice the present invention, and the scope of the present invention is not limited to the following examples.

[0204]

[0205] Comparative Example 1

[0206] Ni 0.6 Co 0.1 Mn 0.3 (OH)2 and Li2CO3 were mixed so that the molar ratio of (Ni+Co+Mn) : Li was 1:1.05, and calcined at 970℃ for 11 hours to obtain LiNi 0.6 Co 0.1 Mn 0.3A single particle lithium nickel oxide having a composition of O2 was prepared. The lithium nickel oxide was used as a positive electrode active material.

[0207]

[0208] Example 1

[0209] CH3COOLi, ( CH3COO)2Mn, Al(NO3)3 were mixed so that the molar ratio of Li:Mn:Al was 2:3:1, and heat-treated at 600°C for 12 hours to prepare a coating raw material including Li2Mn3AlO8.

[0210] The above coating raw material was mixed with the single-particle lithium nickel oxide manufactured in Comparative Example 1, and then heat-treated at 400°C for 3 hours to manufacture a positive electrode active material including a coating layer containing Li2Mn3AlO8.

[0211] It was confirmed that the above Li2Mn3AlO8 was included in an amount of 10,000 ppm based on the total weight of the positive electrode active material.

[0212]

[0213] Example 2

[0214] LiOH, ( CH3COO)2Mn, (NH4)6Mo7O 24 Li:Mn:Mo were mixed in a molar ratio of 8:8:12 and heat-treated at 400℃ for 12 hours to obtain Li8Mn8Mo 12 O 48 A coating raw material including was manufactured.

[0215] After mixing the above coating raw material and the single particle lithium nickel oxide manufactured in Comparative Example 1, heat treatment was performed at 400°C for 3 hours to produce Li8Mn8Mo 12 O 48 A positive electrode active material including a coating layer including was manufactured.

[0216] The above Li8Mn8Mo 12 O 48It was confirmed that it was included in an amount of 10,000 ppm based on the total weight of the above positive electrode active material.

[0217]

[0218] Experimental Example 1: Confirmation of Coating Components

[0219] XRD analysis was performed on the coating raw materials manufactured in Examples 1 and 2 using a Bruker D8 Endeavor X-ray differactometer. Through this, the coating components included in the coating layer of the positive electrode active materials manufactured in Examples 1 and 2 were confirmed.

[0220] Specifically, for the coating raw materials manufactured in Examples 1 and 2, an X-ray diffraction analysis pattern was obtained by measuring the 2θ range of 10° to 80° at 40 kV based on Cu-Kα radiation. In the case of Example 1, the obtained X-ray diffraction analysis pattern was compared with the X-ray diffraction analysis pattern obtained through the structural simulation of Li2Mn3AlO8, and in the case of Example 2, the obtained X-ray diffraction analysis pattern was compared with the Li8Mn8Mo 12 O 48 The X-ray diffraction analysis pattern references were compared. Through this comparison, Li2Mn3AlO8 and Li8Mn8Mo were found in the X-ray diffraction patterns of the coating raw materials manufactured in Examples 1 and 2, respectively. 12 O 48 By the presence of a peak corresponding to the crystal phase, Li2Mn3AlO8 and Li8Mn8Mo were added to the coating raw materials manufactured in Examples 1 and 2. 12 O 48 It was confirmed that this was formed. The results are shown in Figures 1 and 2, respectively.

[0221] Referring to FIGS. 1 and 2, Li2Mn3AlO8 was formed in the coating raw material manufactured in Example 1, and Li8Mn8Mo was formed in the coating raw material manufactured in Example 2. 12 O 48 You can confirm that this has been formed.

[0222]

[0223] Experimental Example 2: Evaluation of Low-Temperature Output Characteristics

[0224] Each of the positive electrode active materials, positive electrode conductive agent (super C), and positive electrode binder (PVdF) manufactured in Comparative Example 1 and Examples 1 to 2 were mixed in a weight ratio of 95:2:3 in N-methyl pyrrolidone to manufacture a positive electrode slurry. The positive electrode slurry was applied onto an aluminum current collector, dried, and rolled to manufacture a positive electrode.

[0225] A lithium metal electrode was used as the cathode.

[0226] An electrode assembly was manufactured by interposing a porous polyethylene separator between the positive and negative electrodes manufactured as described above, and the electrode assembly was placed inside a case, and then an electrolyte was injected into the case to manufacture a lithium secondary battery. At this time, the electrolyte was manufactured by dissolving 1 M lithium hexafluorophosphate (LiPF6) in an organic solvent mixed with ethylene carbonate, dimethyl carbonate, and diethyl carbonate in a weight ratio of 1:2:1.

[0227] The lithium secondary batteries manufactured as described above were each charged to SOC 20, placed in a low-temperature (-10°C) chamber and left for 3 hours, and then continuously discharged at a 2C constant current for 18 seconds to measure the voltage drop at low temperature. The resistance (R = ΔV / I) was calculated by dividing the voltage drop (ΔV) for 0 to 18 seconds by the current value (I). This is shown in Table 1 below.

[0228] Low temperature resistance (Ω) Comparative example 1266 Example 1231 Example 2249

[0229] Through the above Table 1, it can be confirmed that the low-temperature resistance of the lithium secondary battery applying the positive electrode active material of Examples 1 and 2 in which a coating layer including the compound of [Chemical Formula 2] is formed is significantly lower than that of the lithium secondary battery applying the positive electrode active material of Comparative Example 1 in which a coating layer is not formed.

Claims

1. Lithium nickel oxide; and A cathode active material comprising a coating layer formed on the lithium nickel-based oxide and containing a compound represented by the following [chemical formula 2]. [Chemical Formula 2] Li x Mn y M 4 z O w In the above [chemical formula 2], the above M 4 is Al or Mo, x is an integer from 2 to 8, y is an integer from 2 to 8, z is an integer from 1 to 12, and w is an integer from 8 to 48.

2. In claim 1, The compound represented by the above [chemical formula 2] is Li2Mn3AlO8 or Li8Mn8Mo 12 O 48 A positive electrode active material.

3. In claim 1, A cathode active material in which the compound represented by the above [chemical formula 2] is included in an amount of 100 ppm to 20,000 ppm based on the total weight of the cathode active material.

4. In claim 1, The above lithium nickel oxide is a positive electrode active material represented by the following [chemical formula 1]. [Chemical Formula 1] Li a Ni b Co c M 1 d M 2 e O2 In the above [chemical formula 1], M 1 is Mn, Al or a combination thereof, and M 2 Contains at least one element selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.9≤a≤1.1, 0.5≤b<1, 0 <c<0.5, 0<d<0.5, 0≤e≤0.2임.

5. In claim 1, The above lithium nickel-based oxide is a cathode active material that is a single particle lithium nickel-based oxide containing 50 or fewer nodules.

6. In claim 1, The above lithium nickel-based oxide is a positive electrode active material having a Ni content of 50 mol% to 80 mol% among all metals excluding lithium.

7. In claim 1, The above lithium nickel-based oxide is a positive electrode active material represented by the following [chemical formula 1-1]. [Chemical Formula 1-1] Li a1 [Ni b1 Co c1 Mr d1 M 3 e1 ]O2 In the above [chemical formula 1-1], M 3 It contains at least one element selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.9≤a1≤1.1, 0.5≤b1≤0.8, 0 <c1<0.5, 0<d1<0.5, 0≤e1≤0.2임.

8. Li-containing substances, Mn-containing substances and M 4 Containing substance (here, M 4 A step of preparing a coating raw material by mixing Al or Mo; and A method for producing a positive electrode active material, comprising: a step of mixing the above coating raw material and lithium nickel-based oxide and performing heat treatment to form a coating layer containing a compound represented by the following [chemical formula 2] on the lithium nickel-based oxide. [Chemical Formula 2] Li x Mn y M 4 z O w In the above [chemical formula 2], the above M 4 is Al or Mo, x is an integer from 2 to 8, y is an integer from 2 to 8, z is an integer from 1 to 12, and w is an integer from 8 to 48.

9. In claim 8, A method for producing a cathode active material, wherein the Li-containing material comprises CH3COOLi, LiNO3, LiH3C2O2, LiOH, Li2CO3 or a combination thereof.

10. In claim 8, The above Mn-containing material is ( A method for producing a cathode active material comprising CH3COO)2Mn, MnCO3, MnO, MnO2, Mn2O3, Mn3O4, MnH6C4O4 or a combination thereof.

11. In claim 8, Above M 4 Containing materials are Al2O3, AlN, Al(NO3)3, MoO3, (NH4)6Mo7O 24 A method for producing a positive electrode active material, comprising a combination thereof.

12. In claim 8, A method for producing a positive electrode active material, wherein the above coating raw material and lithium nickel oxide are mixed by a dry or wet process.

13. In claim 8, A method for manufacturing a positive electrode active material, wherein the above heat treatment is performed at 100°C to 1000°C for 1 to 12 hours.

14. In claim 8, The step of preparing the above coating raw material includes a Li-containing material, a Mn-containing material, and an M 4 Containing substance (here, M 4 A step of forming a mixture by mixing Al or Mo); and A method for producing a positive electrode active material, comprising: a step of forming a coating raw material by pre-heat treating the above mixture.

15. In claim 14, A method for manufacturing a positive electrode active material, wherein the above pre-heat treatment is performed at 100°C to 1000°C for 3 to 20 hours.

16. A positive electrode comprising the positive electrode active material of any one of claims 1 to 7.

17. A lithium secondary battery comprising the positive electrode of claim 16; a negative electrode disposed opposite the positive electrode; and an electrolyte.

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