Positive electrode active material, method for preparing same, and positive electrode and lithium secondary battery comprising same

Abstract

The present invention relates to a positive electrode active material and a method for preparing same, the positive electrode active material comprising: a single-particle-type lithium nickel-based oxide including 50 or fewer nodules; and a coating layer formed on the lithium nickel-based oxide and containing a lithium metal oxide including Nb and M, wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg, and Si.

Description

Anode active material, method for manufacturing the same, anode including the same, and lithium secondary battery

[0001] The present invention relates to a positive electrode active material, a method for manufacturing a positive electrode active material, a positive electrode comprising said positive electrode active material, and a lithium secondary battery. More specifically, the invention relates to a positive electrode active material having excellent low-temperature output characteristics, a method for manufacturing said positive electrode active material, and a positive electrode comprising said positive electrode active material and a lithium secondary battery.

[0002] A lithium secondary battery is generally manufactured by forming an electrode assembly by interposing a separator between a positive electrode containing a positive active material composed of a transition metal oxide containing lithium and a negative electrode containing a negative 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 transmitting lithium ions, and then sealing it.

[0003] These lithium-ion batteries are used not only in portable electronic devices such as mobile phones and laptops but also in electric vehicles, and demand is surging recently due to the expansion of electric vehicle adoption. Lithium-ion batteries used in electric vehicles require high energy density, high power output characteristics, and durability to operate for extended periods in harsh environments, such as low or high temperatures.

[0004] However, lithium-ion batteries for electric vehicles developed to date have a problem in that their performance is limited during winter or in cold regions because lithium-ion mobility decreases in low-temperature environments, leading to increased resistance and a rapid decline in capacity and output.

[0005] Therefore, there is a need to develop lithium secondary batteries with excellent low-temperature output characteristics.

[0006] The present invention aims to solve the above-mentioned problems by forming a coating layer with low lithium transport barrier energy on the surface of a single-particle lithium nickel-based oxide, thereby providing a positive electrode active material with excellent lithium ion mobility even at low temperatures and a method for manufacturing the same.

[0007] In addition, the present invention aims to provide a positive electrode having excellent low-temperature output characteristics by including the positive electrode active material as described above, and a lithium secondary battery including the same.

[0008] [1] The present invention provides a positive electrode active material comprising: a single-particle lithium nickel-based oxide having 50 or fewer nodules; and a coating layer formed on the lithium nickel-based oxide and comprising a lithium metal oxide having Nb and M, wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si.

[0009] [2] The present invention provides a positive electrode active material in which, in [1] above, the lithium metal oxide is represented by the following [Chemical Formula 2].

[0010] [Chemical Formula 2]

[0011] Li x Nb y M z O w

[0012] In the above chemical formula 2, M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si, and 1≤x≤5, 1≤y≤40, 1≤z≤40, 1≤w≤35.

[0013] [3] The present invention is such that, in [1] or [2], the lithium metal oxide is Li x Nb y Mg z O w, Li x Nb y Bi z Ow, Li x Nb y Si z1 Mg z2 O w, Li x Nb y Si z1 Bi z3 O w, Li x Nb y Mg z2 Bi z3 O w, or Li x Nb y Si z1 Mg z2 Bi z3 O w A positive active material is provided (where 1≤x≤5, 1≤y≤40, 1≤z≤40, 1≤w≤35, z1+z2+z3=z).

[0014] [4] The present invention provides a positive electrode active material in which, in at least one of [1] to [3], the lithium metal oxide is included in an amount of 100 ppm to 10,000 ppm based on the total weight of the positive electrode active material.

[0015] [5] The present invention provides a positive electrode active material in which, in at least one of [1] to [4], the single-particle lithium nickel-based oxide has a composition represented by the following [Chemical Formula 1].

[0016] [Chemical Formula 1]

[0017] Li a Ni b Co c M 1 d M 2 e O2

[0018] In the above [Chemical Formula 1], M 1 is Mn, Al, or a combination thereof, and M 2... comprises one or more elements 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.

[0019] [6] The present invention provides a positive electrode active material in which, in at least one of [1] to [5], the lithium nickel-based oxide comprises 50 mol% to 80 mol%, preferably 50 mol% to 75 mol%, more preferably 50 mol% to 70 mol% of the total metal excluding lithium.

[0020] [7] The present invention provides a positive electrode active material in which, in at least one of [1] to [6], the lithium nickel-based oxide has a composition represented by the following [Chemical Formula 1-1].

[0021] [Chemical Formula 1-1]

[0022] Li a1 [Ni b1 Co c1 Mn d1 M 3 e1 ]O2

[0023] In the above [Chemical Formula 1-1], M 3 ... comprises one or more elements 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.

[0024] [8] The present invention provides a method for manufacturing an anode active material comprising the steps of: preparing a coating raw material by mixing an Nb-containing material, an M-containing material (wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si) and a Li-containing material; and mixing the coating raw material with a single-particle lithium nickel-based oxide and heat-treating the mixture to form a coating layer containing a lithium metal oxide containing Nb and M on the lithium nickel-based oxide.

[0025] [9] The present invention provides a method for manufacturing a positive electrode active material, wherein the Nb-containing material in [8] comprises Nb2O5, NbO2, NbF5 or a combination thereof.

[0026]

[0010] The present invention provides a method for manufacturing a positive electrode active material, wherein, in [8] or [9], the M-containing material comprises one or more selected from the group consisting of Mg(NO3)2, MgCO3, MgF2, MgO, MgSO4, Mg3N2, MgH6C4O4, Mg(OH)2, Bi, BiF3, Bi(NO3)3, Bi2O3, Bi(CH3CO2)3, and BiPO4.

[0027]

[0011] The present invention provides a method for manufacturing a positive electrode active material, wherein the M-containing material in

[0010] further comprises one or more selected from the group consisting of SiC, Si3N4, SiO2, (OH)2SiO, Si(OH)4, Si, Si(OCOCH3)4, and Si(OC2H5)4.

[0028]

[0012] The present invention provides a method for manufacturing a positive electrode active material, wherein, in any one of [8] to

[0011] , the Li-containing material comprises LiH, LiNO3, Li2CO3, LiOH, LiH3C2O2 or a combination thereof.

[0029]

[0013] The present invention provides a method for manufacturing an anode active material, wherein, in any one of [8] to

[0012] , the coating raw material and the single-particle lithium nickel-based oxide are mixed dry or wet.

[0030]

[0014] The present invention provides a method for manufacturing an anode active material, wherein, in any one of [8] to

[0013] , the heat treatment is performed at 400°C to 1000°C for 3 to 12 hours.

[0031]

[0015] The present invention provides a method for manufacturing an anode active material, wherein, in any one of [8] to

[0014] , the step of preparing the coating raw material comprises: mixing an Nb-containing material, an M-containing material (wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si) and a Li-containing material to form a mixture; and pre-heat treating the mixture to form the coating raw material.

[0032]

[0016] The present invention provides a method for manufacturing an anode active material, wherein, in

[0015] the prior heat treatment is performed at 400°C to 1000°C for 3 to 12 hours.

[0033]

[0017] The present invention provides a positive electrode comprising a positive electrode active material according to at least one of [1] to [7].

[0034]

[0018] The present invention provides a lithium secondary battery comprising: a positive electrode according to

[0017] ; a negative electrode disposed opposite to the positive electrode; and an electrolyte.

[0035] The cathode active material according to the present invention comprises a coating layer containing Nb and M (wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg, and Si) on the surface of a single-particle lithium nickel-based oxide. When a coating layer containing Nb and M is formed on the surface of a single-particle lithium nickel-based oxide as in the present invention, a more stable compound is formed than a coating layer containing other metals, thereby reducing side reactions with the electrolyte and the formation of resistors, and forming a lithium path (Li path) to improve output. 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.

[0036] The present invention will be described in more detail below.

[0037] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0038] In the present invention, "single particle type" refers to a particle composed of 50 or fewer nodules, and is a concept that includes a single particle composed of one nodule and a pseudo-single particle which is a complex of 2 to 50 nodules.

[0039] The above “nodule” is a sub-grain unit constituting a single particle and a pseudo-single particle, and may be a single crystal that does not have crystalline grain boundaries, or a polycrystalline one in which no grain boundaries appear to exist when observed at a field of view of 5,000 to 20,000 times using a scanning electron microscope.

[0040] In the present invention, "secondary particle" refers to a particle formed by the aggregation of a plurality of primary particles, for example, tens to hundreds of primary particles. Specifically, the secondary particle may be an aggregate of more than 50 primary particles.

[0041] In the present invention, the term “particle” is a concept that includes any one or all of a single particle, a pseudo-single particle, a primary particle, a nodule, and a secondary particle.

[0042] In the present invention, the average particle size (D) of the nodule or primary particle mean ) refers to the arithmetic mean value calculated after measuring the particle sizes of nodules or primary particles observed in scanning electron microscope images.

[0043] In the present invention, "average particle size D 50 "This refers to the particle size corresponding to 50% of the volume cumulative amount of the volume cumulative particle size distribution of the powder to be measured, and can be measured using the laser diffraction method. For example, the powder to be measured can be measured by dispersing it in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasound of about 28 kHz at an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then determining the particle size corresponding to 50% of the volume cumulative amount.

[0044]

[0045] positive electrode active material

[0046] First, the positive active material according to the present invention will be described.

[0047] The positive electrode active material according to the present invention comprises: a single-particle lithium nickel-based oxide having 50 or fewer nodules; and a coating layer formed on the lithium nickel-based oxide and comprising a lithium metal oxide having Nb and M (wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si).

[0048] Conventional lithium nickel-based oxides generally consist of secondary particles formed by the aggregation of tens to hundreds of primary particles. These conventional secondary particle-type lithium nickel-based oxides present problems, such as a susceptibility to particle breakage where primary particles detach during the rolling process in cathode manufacturing, and the occurrence of internal cracks during charge-discharge cycles. If particle breakage or cracking occurs in the cathode active material, the contact area with the electrolyte increases, leading to increased gas generation and active material degradation due to adverse reactions with the electrolyte. Consequently, this results in reduced lifespan characteristics and safety. In particular, with the recent increase in demand for high-capacity batteries, the nickel content in lithium nickel-based oxides is gradually increasing. While an increase in nickel content in the cathode active material improves initial capacity characteristics, repeated charge-discharge cycles [cause] the highly reactive nickel +4 There is a problem in that the excessive generation of ions causes structural collapse of the cathode active material, which increases the degradation rate of the cathode active material, leading to reduced lifespan characteristics and decreased battery safety.

[0049] To address these issues, a lithium nickel-based oxide with a single-particle form was developed by increasing the calcination temperature during manufacturing. Since single-particle lithium nickel-based oxides have fewer internal interfaces and higher particle strength, their application can reduce gas generation and particle breakage. However, single-particle lithium nickel-based oxides have long internal lithium pathways and few inter-particle interfaces, resulting in poor lithium ion mobility. Consequently, they exhibit relatively high resistance, which leads to inferior output characteristics, particularly at low temperatures.

[0050] Accordingly, the inventors of the present invention conducted repeated research to improve the output characteristics of single-particle lithium nickel-based oxides, particularly low-temperature output characteristics, and discovered that the low-temperature output characteristics of single-particle lithium nickel-based oxides can be significantly improved by forming a coating layer on the surface of the single-particle lithium nickel-based oxide comprising Nb and Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg, and Si, thereby completing the present invention.

[0051]

[0052] Hereinafter, each component of the positive active material according to the present invention will be described.

[0053]

[0054] (1) Lithium nickel-based oxide

[0055] The positive electrode active material according to the present invention comprises a single-particle lithium nickel-based oxide containing 50 or fewer nodules.

[0056] In the case of single-particle lithium nickel-based oxides, compared to secondary-particle lithium nickel-based oxides, there is less particle breakage due to rolling during cathode manufacturing and excellent structural stability under high temperature and / or high voltage conditions. Therefore, when single-particle lithium nickel-based oxides are applied, cathode degradation is reduced under high temperature and high voltage conditions, and there is less generation of fine particles after cathode manufacturing, resulting in less gas generation due to side reactions between fine particles and the electrolyte. Thus, when single-particle lithium nickel-based oxides are applied, it is advantageous for manufacturing lithium secondary batteries with long life characteristics.

[0057] The above single-particle lithium nickel-based oxide may contain 50 or fewer nodules, preferably 30 or fewer, more preferably 1 to 25, and even more preferably 1 to 15 nodules. This is because if the above single-particle lithium nickel-based oxide contains an excessive number of nodules, particle breakage increases during electrode manufacturing, and the occurrence of internal cracks due to volume expansion / contraction of nodules during charging and discharging increases, which may result in inferior high-temperature life characteristics and high-temperature storage characteristics.

[0058] The above nodules may have an average particle size of 0.8㎛ to 4.0㎛, preferably 0.8㎛ to 3㎛, and more preferably 1.0㎛ to 3.0㎛. When the average particle size of the nodules satisfies the above range, particle breakage during electrode manufacturing is minimized, and the increase in resistance can be suppressed more effectively. At this time, the average particle size of the nodules refers to a value obtained by measuring the particle sizes of the nodules observed in the SEM image obtained by analyzing the positive electrode active material powder with a scanning electron microscope, and then calculating the arithmetic mean of the measured values.

[0059] The above single-particle lithium nickel-based oxide is D 50 This can be 2.0㎛ to 10.0㎛, preferably 2.0㎛ to 8.0㎛. More preferably, it is about 3.0㎛ to 7.0㎛. D of lithium nickel-based oxide 50If this is too small, processability during electrode manufacturing decreases, and electrolyte impregnation decreases, which may increase electrochemical properties, and D 50 If this is too large, there is a problem in that resistance increases and output characteristics deteriorate.

[0060] The above single-particle lithium nickel-based oxide may have a composition represented by, for example, [Chemical Formula 1] below.

[0061] [Chemical Formula 1]

[0062] Li a Ni b Co c M 1 d M 2 e O2

[0063] In the above [Chemical Formula 1], M 1 It is Mn, Al, or a combination thereof, and preferably may be Mn or a combination of Mn and Al.

[0064] The above M 2 is a doping element doped into transition metal sites included in the above lithium nickel-based oxide, M 2 When an element is included, effects such as suppressing cation mixing of the positive electrode active material and suppressing structural changes during repeated charge and discharge cycles can be obtained. The above M 2 It 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.

[0065] The above 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.

[0066] The above 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, 0.5≤b≤0.75, or 0.5≤b≤0.70.

[0067] The above c represents the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel-based oxide, where 0 <c<0.5, 0.01≤c<0.5, 0.05≤c<0.5, 0.1≤c<0.5 또는 0.1≤c≤0.4일 수 있다.

[0068] The above d is M among the total metals excluding lithium in lithium nickel-based oxides. 1 Representing the molar ratio of, 0 <d<0.5, 0.01≤d<0.5, 0.05≤d<0.5, 0.1≤d<0.5 또는 0.1≤d≤0.4일 수 있다.

[0069] The above e is M among the total metals excluding lithium in lithium nickel-based oxides. 2 It represents the molar ratio of 0≤e≤0.2, 0≤e≤0.15, or 0≤e≤0.10.

[0070]

[0071] Preferably, 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% among the total metals excluding lithium. In the case of a single-particle lithium nickel-based oxide with a nickel content of 50 mol% to 80 mol%, structural stability at high voltage is higher compared to a lithium nickel-based oxide with a nickel content exceeding 80 mol% or having a secondary particle form; therefore, degradation of lifespan characteristics during high-voltage operation can be minimized. As the nickel content in the lithium nickel-based oxide increases, the highly reactive Ni +4As the number of ions increases, the structural stability of the positive electrode active material decreases during charging and discharging, leading to rapid positive electrode degradation. This phenomenon is further exacerbated during high-voltage operation. When a lithium nickel-based oxide with a low Ni content of 80 mol% or less is applied, the reduction in lifespan caused by active material degradation during high-voltage operation can be suppressed more effectively. However, since capacity characteristics deteriorate if the Ni content is too low, it is preferable that the Ni content of the lithium nickel-based oxide be approximately 50 mol% to 80 mol%.

[0072] Specifically, the above-mentioned single-particle lithium nickel-based oxide may be a lithium transition metal oxide containing nickel, manganese, and cobalt, and, for example, may be represented by the following [Chemical Formula 1-1].

[0073] [Chemical Formula 1-1]

[0074] Li a1 [Ni b1 Co c1 Mn d1 M 3 e1 ]O2

[0075] In the above [Chemical Formula 1-1], M 2 It 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. 3 When the element is included, the structural stability of the lithium nickel-based oxide particles is improved, enabling superior lifespan characteristics during high-voltage operation. Preferably, the above M 3 The elements may include one or more selected from the group consisting of Ti, Mg, Al, Zr, and Y, and more preferably, may include two or more selected from the group consisting of Ti, Mg, Al, Zr, and Y.

[0076] 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.

[0077] 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≤0.75, or 0.55≤b1≤0.7. When b1 satisfies the above range, high temperature and / or high voltage stability is excellent.

[0078] The above c1 represents the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel-based oxide, where 0 <c1<0.5, 0.05≤c1≤0.4 또는 0.1≤c1≤0.4일 수 있다.

[0079] The above d1 represents the molar ratio of manganese among the total metals excluding lithium in the lithium nickel-based oxide, where 0 <d1<0.5, 0.05≤d1≤0.4 또는 0.1≤d1≤0.4일 수 있다.

[0080] The above e1 is M among the total metals excluding lithium in the lithium nickel-based oxide. 3 Representing the molar ratio of elements, 0≤e1≤0.2, 0≤e1≤0.1, or 0 <e1≤0.1일 수 있다. M 3 When the molar ratio of the elements satisfies the above range, both the structural stability and capacity of the positive active material can be excellent.

[0081]

[0082] (2) Coating layer

[0083] 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 the leaching of transition metals.

[0084] The coating layer according to the present invention comprises a lithium metal oxide, wherein the lithium metal oxide comprises Nb and M (wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si).

[0085] When a coating layer containing Nb and M (where M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si) is formed on the surface of a single-particle lithium nickel-based oxide, a more stable compound is formed than a coating layer containing other metals, which reduces side reactions with the electrolyte and resistance formation, and creates a lithium path (Li path) to improve output.

[0086] Preferably, the lithium metal oxide may be represented by the following [Chemical Formula 2].

[0087] [Chemical Formula 2]

[0088] Li x Nb y M z O w

[0089] In the above chemical formula 2, M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si, and 1≤x≤5, 1≤y≤40, 1≤z≤40, 1≤w≤35.

[0090] Specifically, the lithium metal oxide is Li x Nb y Mg z O w, Li x Nb y Bi z O w, Li x Nb y Si z1 Mg z2 O w, Li x Nb y Si z1 Biz3 O w, Li x Nb y Mg z2 Bi z3 O w, or Li x Nb y Si z1 Mg z2 Bi z3 O w (where 1≤x≤5, 1≤y≤40, 1≤z≤40, 1≤w≤35, z1+z2+z3=z) and more specifically, it may be LiMgNbO4, LiNbSiO5, LiNi3(Bi2O7)2 or a combination thereof.

[0091]

[0092] In the present invention, the lithium metal oxide may be included in an amount of 100 ppm to 10,000 ppm based on the total weight of the positive electrode active material. If the content of the lithium metal oxide is too high, the capacity characteristics of the positive electrode active material are degraded, and if it is too low, the effect of improving low-temperature performance is negligible.

[0093]

[0094] Method for manufacturing positive electrode active material

[0095] Next, a method for manufacturing a positive electrode active material according to the present invention will be described.

[0096] A method for manufacturing a positive electrode active material according to the present invention comprises: (1) a step of preparing a coating raw material by mixing an Nb-containing material; an M-containing material (wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si); and a Li-containing material; and (2) a step of forming a coating layer on the lithium nickel-based oxide by mixing the coating raw material and the lithium nickel-based oxide and heat-treating the mixture.

[0097] First, a coating raw material is prepared by mixing an Nb-containing material, an M-containing material (where M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg, and Si), and a Li-containing material.

[0098] The above coating raw material is intended for synthesizing lithium metal oxide and may be in the form of a mixture of the Nb-containing material, M-containing material, and Li-containing material, or it may be a material formed by mixing the Nb-containing material, M-containing material, and Li-containing material to form a mixture, and then pre-heat-treating the mixture.

[0099] The above Nb-containing material may be an oxide, nitride, halide, hydroxide, carbonate, nitrate, or combination thereof containing niobium, and may include, for example, Nb2O5, NbO2, NbF5, or a combination thereof, but is not limited thereto.

[0100] The above M-containing material may be an oxide, nitride, halide, hydroxide, carbonate, nitrate, or combination thereof containing M, and may include, for example, SiC, Si3N4, SiO2, (OH)2SiO, Si(OH)4, Si, Si(OCOCH3)4, Si(OC2H5)4, Mg(NO3)2, MgCO3, MgF2, MgO, MgSO4, Mg3N2, MgH6C4O4, Mg(OH)2, Bi, BiF3, Bi(NO3)3, Bi2O3, Bi(CH3CO2)3, BiPO4, or a combination thereof, but is not limited thereto. Specifically, the M-containing material may include one or more selected from the group consisting of Mg(NO3)2, MgCO3, MgF2, MgO, MgSO4, Mg3N2, MgH6C4O4, Mg(OH)2, Bi, BiF3, Bi(NO3)3, Bi2O3, Bi(CH3CO2)3, and BiPO4, and optionally may additionally include one or more selected from the group consisting of SiC, Si3N4, SiO2, (OH)2SiO, Si(OH)4, Si, Si(OCOCH3)4, and Si(OC2H5)4.

[0101] The above Li-containing material may include oxides, nitrides, halides, hydroxides, carbonates, nitrates, or combinations thereof containing Li, and may include, for example, LiH, LiNO3, Li2CO3, LiOH, LiH3C2O2, or combinations thereof, but is not limited thereto.

[0102] Meanwhile, the mixing ratio of the above Nb-containing material, M-containing material, and Li-containing material can be mixed in an amount such that the molar ratio of Li : Nb : M in the mixture is 0.1 to 4 : 1 to 4 : 1 to 4. When the content of each component in the mixture satisfies the above range, it is advantageous to synthesize a lithium metal oxide containing Nb and M.

[0103] Meanwhile, when performing a preheat treatment, the preheat treatment may be performed, for example, at 400°C to 1000°C for 3 to 12 hours. When the preheat treatment is performed under the above conditions, it is advantageous to synthesize a lithium metal oxide containing Nb and M.

[0104]

[0105] Once the coating raw material is prepared through the above process, the prepared coating raw material is mixed with lithium nickel-based oxide and heat-treated to form a coating layer.

[0106] The method of mixing the above-mentioned coating raw material and the lithium nickel-based oxide is not particularly limited and can be performed by dry mixing or wet mixing. For example, the solid-phase coating raw material and the solid-phase lithium nickel-based oxide can be mixed dry by adding a mixer or similar device and stirring, or the coating raw material and the lithium nickel-based oxide can be mixed wet by adding them to a solvent such as water or ethanol and stirring.

[0107] Meanwhile, the heat treatment can be performed at 400°C to 1000°C for 3 to 12 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 to synthesize a lithium metal oxide containing Nb and M.

[0108]

[0109] anode

[0110] Next, the anode according to the present invention comprises the aforementioned anode active material. Specifically, the anode may comprise an anode active material layer comprising the aforementioned anode active material, and more specifically, may comprise an anode current collector; and an anode active material layer located on the anode current collector and comprising the aforementioned anode active material.

[0111]

[0112] Hereinafter, each component of the anode according to the present invention will be described in detail.

[0113]

[0114] (1) Positive current collector

[0115] Various positive current collectors used in the relevant technical field may be used as the positive current collector. For example, the positive 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 current collector may typically have a thickness of 3 to 500 μm, and fine irregularities may be formed on the surface of the positive current collector to increase the adhesion of the positive active material. The positive current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0116]

[0117] (2) Positive active material layer

[0118] The positive active material layer may be located on the positive current collector, and specifically, may be located on one or both sides of the positive current collector. The positive active material layer may be a single layer or a multilayer structure of two or more layers.

[0119] The above positive active material layer may include a positive active material, a positive conductive material, and a positive binder.

[0120] At this time, the positive active material is the positive active material according to the present invention as described above, and the specific characteristics of the positive active material are the same as those described above.

[0121] The above positive active material may be included in an amount of 90% to 99% by weight, preferably 92% to 98% by weight, and more preferably 94% to 98% by weight, based on the total weight of the positive active material layer. If the above range is satisfied, the energy density and capacity characteristics of the lithium secondary battery to which the positive material is applied can be improved.

[0122] The above-mentioned positive electrode conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, carbon nanotube; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. The above-mentioned positive electrode conductive material may typically be included in an amount of 0.1 to 10 weight%, preferably 0.1 to 8 weight%, and more preferably 0.1 to 5 weight% based on the total weight of the positive electrode active material layer.

[0123] The above-mentioned anode binder serves to improve adhesion between anode material particles and adhesion between the anode material and the anode current collector. Specific examples include fluoropolymer-based binders comprising polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber-based binders comprising styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose-based binders comprising carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyalcohol-based binders comprising polyvinyl alcohol; polyolefin-based binders comprising polyethylene or polypropylene; polyimide-based binders; and polyester-based binders. Examples include silane-based binders, and one of these alone or a mixture of two or more may be used. The anode binder may be included in an amount of 1 to 10 weight%, preferably 0.5 to 10 weight%, and more preferably 1 to 8 weight% based on the total weight of the anode active material layer.

[0124]

[0125] The anode may be manufactured by methods known in the art. For example, the anode may be manufactured by mixing an anode active material, an anode binder, and an anode conductive material in a solvent to prepare an anode slurry, applying the anode slurry onto an anode current collector, and then drying and rolling, or by casting the anode slurry onto a separate support and then laminating the film obtained by peeling it off from the support onto an anode current collector. In this case, the solvent for the anode slurry may be any anode slurry solvents generally used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, or a mixture thereof, but is not limited thereto. The solvent may be used in an amount that dissolves or disperses the anode active material, the anode conductive material, and the anode binder, and has a viscosity such that the anode slurry can be uniformly coated.

[0126]

[0127] lithium secondary battery

[0128] Next, a lithium secondary battery according to the present invention will be described. The lithium secondary battery according to the present invention comprises a positive electrode according to the present invention; a negative electrode disposed opposite to the positive electrode; and an electrolyte. Optionally, the lithium secondary battery according to the present invention may further comprise a separator interposed between the positive electrode and the negative electrode.

[0129] Since the anode above is the same as described above, the remaining components excluding the anode will be described below.

[0130]

[0131] (1) Cathode

[0132] In a lithium secondary battery according to the present invention, the negative electrode comprises 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.

[0133]

[0134] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. In addition, the above-mentioned negative current collector may typically have a thickness of 3 to 500 μm, and, similar to the positive current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0135]

[0136] The above negative electrode active material layer may be located on the negative electrode current collector, and specifically, may be located on one or both sides of the negative electrode current collector. The above negative electrode active material layer may have a single-layer structure or a multi-layer structure of two or more layers.

[0137] When the negative electrode active material layer is a multilayer structure composed of two or more layers, the types and / or contents of the negative electrode active material, negative electrode binder, and / or negative electrode conductive material in each layer may differ from one another. 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.

[0138] Meanwhile, as the above-mentioned 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 alloys, Sn alloys, or Al alloys; and SiO₂ β Examples include metal oxides capable of doping and dedoping lithium, such as (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used.

[0139] Meanwhile, both low-crystallinity carbon and high-crystallinity carbon can be used as the aforementioned carbonaceous materials. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0140] Preferably, the cathode active material may be a carbon-based cathode active material, wherein the carbon-based cathode 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 cathode active material may include natural graphite and artificial graphite.

[0141] The above carbon-based negative electrode active material has an average particle size D 50 This can be 2㎛ to 30㎛, preferably 5㎛ to 30㎛.

[0142] The above-mentioned negative electrode active material may be included in an amount of 80% to 98% by weight, preferably 90% to 98% by weight, and more preferably 93% to 98% by weight, 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.

[0143]

[0144] Meanwhile, the above-mentioned cathode active material layer may further include a cathode conductive material and / or a cathode binder together with the cathode active material.

[0145] The cathode conductive material is used to impart conductivity to the cathode, and in the battery being constructed, it can be used without special restrictions as long as it has electronic conductivity without causing chemical changes. Specific examples include carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, 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 one of these alone or a mixture of two or more of them may be used.

[0146] The above-mentioned cathode conductive material may typically be included in an amount of 0.1 to 10 weight%, preferably 0.1 to 8 weight%, and more preferably 0.1 to 5 weight% based on the total weight of the cathode active material layer.

[0147] The above-mentioned cathode binder serves to improve adhesion between cathode active material particles and adhesion between the cathode active material and the cathode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, 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 alone or a mixture of two or more may be used.

[0148] The above-mentioned cathode binder may be included in an amount of 0.1 to 10 weight%, preferably 0.5 to 10 weight%, and more preferably 1 to 8 weight% based on the total weight of the cathode active material layer.

[0149]

[0150] The above cathode may be manufactured by methods known in the art. For example, the cathode may be manufactured by mixing a cathode active material, a cathode binder, and / or a cathode conductive material in a solvent to prepare a cathode slurry, applying the cathode slurry onto a cathode current collector, and then drying and rolling, or by casting the cathode slurry onto a separate support and then laminating the film obtained by peeling it off from the support onto a cathode current collector.

[0151] Meanwhile, solvents commonly used in the relevant technical field may be used as the solvent for the cathode slurry, for example, dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, or mixtures thereof, but are not limited thereto. The solvent may be used in an amount that dissolves or disperses the cathode active material, cathode conductive material, and cathode binder, and has a viscosity such that the cathode slurry can be uniformly coated.

[0152]

[0153] (2) Electrolyte

[0154] The electrolyte according to the present invention may include a lithium salt and an organic solvent.

[0155] The above lithium salt can be used without special limitations as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, 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 used within the range of 0.1 to 5.0 M, more preferably 0.1 to 3.0 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and allow lithium ions to move effectively.

[0156]

[0157] 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.

[0158] The above-mentioned 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.

[0159] In addition, the above-mentioned linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and as a representative example, 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 may be used, and specifically, it may include ethylmethyl carbonate (EMC).

[0160] Specific examples of the above linear ester-based organic solvent may 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.

[0161] The above-mentioned cyclic ester-based organic solvent may include at least one organic solvent selected from the group consisting of butyrolactone, valerolactone, and caprolactone.

[0162] Preferably, the electrolyte according to the present invention may include ethylene carbonate and dimethyl carbonate as organic solvents.

[0163]

[0164] Meanwhile, in addition to the electrolyte components, the above electrolyte may additionally include other additives for the purpose of improving the lifespan characteristics of the battery, suppressing the reduction of battery capacity, and improving the discharge capacity of the battery.

[0165] These other additives may include at least one other additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds different from the lithium salt contained in the electrolyte, as representative examples.

[0166] Specifically, the above other additives are vinylene carbonate (VC), vinylethylene carbonate, fluoroethylene carbonate (FEC), 1,3-propane sulfone (PS), 1,4-butane sulfone, ethene sulfone, 1,3-propene sulfone (PRS), 1,4-butene sulfone, 1-methyl-1,3-propene sulfone, ethylene sulfate (ESA), trimethylene sulfate (TMS), methyl trimethylene sulfate (MTMS), tetraphenyl borate, lithium oxalyl difluoroborate, succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, Examples include 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 bis-oxalate toborate (LiB(C2O4)2)) and LiBF4.

[0167] The above other additives may be included in an amount of 0.01 to 20 weight% based on the total weight of the electrolyte, and preferably in an amount of 0.05 to 5.0 weight%. If the content of the above other additives is less than 0.01 weight%, the effect of improving low-temperature output, high-temperature storage characteristics, and high-temperature life characteristics of the battery is negligible, and if the content of the above other additives exceeds 20 weight%, there is a possibility that excessive side reactions may occur within the electrolyte during charging and discharging of the battery. In particular, when the above SEI film-forming additives are added in excess, they may not decompose sufficiently at high temperatures and may remain as unreacted substances or precipitated within the electrolyte at room temperature. Accordingly, side reactions that degrade the lifespan or resistance characteristics of the secondary battery may occur.

[0168]

[0169] (3) Separator

[0170] The above separator physically separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions; any separator typically used in lithium secondary batteries can be used without any special restrictions. In this case, the separator may be interposed between the positive electrode and the negative electrode.

[0171] Specifically, a porous polymer film made of a polyolefin-based 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, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0172]

[0173] 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 achieve excellent output characteristics even under low temperature conditions, it can be particularly usefully applied in the field of electric vehicles.

[0174] According to another embodiment of the present invention, a battery module comprising a lithium secondary battery according to the present invention as a unit cell and a battery pack comprising the same are provided.

[0175] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0176]

[0177] The present invention will be explained in more detail below through specific embodiments. However, the following embodiments are intended only to enable a person skilled in the art to fully understand and easily implement the present invention, and the scope of the rights of the present invention is not limited to the following embodiments.

[0178]

[0179] Comparative Example 1

[0180] Ni 0.6 Co 0.1 Mn 0.3 (OH)2 and Li2CO3 are mixed such that the molar ratio of Li : (Ni+Co+Mn) is 1.05 : 1, and calcined at 970°C for 11 hours to produce LiNi 0.6 Co 0.1 Mn 0.3A single-particle lithium nickel-based oxide having the composition of O2 was prepared. The lithium nickel-based oxide was used as a positive electrode active material.

[0181]

[0182] Example 1

[0183] A coating raw material was prepared by mixing LiOH, Nb2O5, and MgO such that the molar ratio of Li:Nb:Mg was 1:1:1.

[0184] A positive electrode active material comprising a coating layer containing LiMgNbO4 was prepared by mixing the above coating raw material with the single-particle lithium nickel-based oxide prepared in Comparative Example 1 and then heat-treating at 600°C for 4 hours. The positive electrode active material contained the lithium metal oxide in an amount of 1000 ppm based on the total weight of the positive electrode active material.

[0185]

[0186] Example 2

[0187] A coating raw material was prepared by mixing Nb2O5, Bi2O5, and LiOH such that the molar ratio of Li : Nb : Bi was 1 : 3 : 4.

[0188] A positive electrode active material comprising a coating layer containing LiNb3(Bi2O7)2 was prepared by mixing the above coating raw material with the single-particle lithium nickel-based oxide prepared in Comparative Example 1 and then heat-treating at 800°C for 4 hours. The positive electrode active material contained the lithium metal oxide in an amount of 2000 ppm based on the total weight of the positive electrode active material.

[0189]

[0190] Example 3

[0191] A coating raw material was prepared by mixing Nb2O5, Si(OC2H-5)4, MgO, and LiOH such that the molar ratio of Li : Nb : Si : Mg was 2 : 2 : 1 : 1.

[0192] A positive electrode active material comprising a coating layer containing LiNbMgO4 and LiNbSiO5 was prepared by mixing the above coating raw material with the single-particle lithium nickel-based oxide prepared in Comparative Example 1 and then heat-treating at 600°C for 4 hours. The positive electrode active material contained the lithium metal oxide in an amount of 2000 ppm based on the total weight of the positive electrode active material.

[0193]

[0194] Comparative Example 2

[0195] A coating raw material was prepared by mixing Al2O3 and WO3 such that the molar ratio of Al to W was 1:2.

[0196] A positive electrode active material comprising a coating layer containing LiAl(WO4)2, LiAlO2, and Li2WO4 was prepared by mixing the above coating raw material with the single-particle lithium nickel-based oxide prepared in Comparative Example 1 and heat-treating at 700°C for 3 hours. The positive electrode active material contained the lithium metal oxide in an amount of 1000 ppm based on the total weight of the positive electrode active material.

[0197]

[0198] Comparative Example 3

[0199] Ti(OCH2CH2CH2CH3)4 (Titanium butoxide, TBOT) and Al(NO3)3 are added to ethanol to achieve an Al:Ti molar ratio of 1:1 and stirred to dissolve for 1 hour; then, the monoparticle lithium nickel-based oxide prepared in Comparative Example 1 is added, and the ethanol is slowly evaporated while gently stirring at 50°C. Subsequently, the mixture is heat-treated at 400°C for 3 hours to produce LiTiAlO4 and Li4Ti5O. 12 A positive electrode active material was prepared comprising a coating layer including , and LiAlO2. The positive electrode active material contained the lithium metal oxide in an amount of 3,000 ppm based on the total weight of the positive electrode active material.

[0200]

[0201] Comparative Example 4

[0202] A coating raw material was prepared by mixing MgO, WO3, and LiOH such that the molar ratio of Li:Mg:W was 4:1:1.

[0203] A positive electrode active material comprising a coating layer containing Li4MgWO6 was prepared by mixing the above coating raw material with the single-particle lithium nickel-based oxide prepared in Comparative Example 1 and then heat-treating at 800°C for 3 hours. The positive electrode active material contained the lithium metal oxide in an amount of 2000 ppm based on the total weight of the positive electrode active material.

[0204]

[0205] Comparative Example 5

[0206] (NH4) 10 (H2W 12 O 42 After dissolving the above in water, the single-particle lithium nickel-based oxide prepared in Comparative Example 1 and Nb2O5 were added to the mixture, and the water was slowly evaporated by stirring at 100°C. Then, a positive electrode active material containing a coating layer containing LiNbWO6 was prepared by heat treatment at 600°C for 6 hours. The positive electrode active material contained the lithium metal oxide in an amount of 1000 ppm based on the total weight of the positive electrode active material.

[0207]

[0208] Experimental Example 1: Evaluation of Low-Temperature Output Characteristics

[0209] A positive electrode slurry was prepared by mixing the respective positive electrode active materials prepared in Comparative Examples 1 to 5 and Examples 1 to 3, the positive electrode conductive material (Super-C), and the positive electrode binder (PVdF) in N-methylpyrrolidone in a weight ratio of 95:2:3. The positive electrode slurry was coated onto an aluminum current collector, dried, and rolled to produce a positive electrode.

[0210] A lithium metal electrode was used as the cathode.

[0211] An electrode assembly was manufactured by interposing a porous polyethylene separator between the anode and cathode manufactured as described above, and after placing the electrode assembly inside a case, an electrolyte was injected into the case to manufacture a lithium secondary battery (coin half-cell). At this time, the electrolyte was prepared by dissolving 1M concentration lithium hexafluorophosphate (LiPF6) in an organic solvent mixed with ethylene carbonate, dimethyl carbonate, and diethyl carbonate in a weight ratio of 1:2:1.

[0212] After charging the above lithium secondary battery to SOC 20 at 0.1C, it was discharged at 2C at 10℃ for 18 seconds to measure the change in voltage (ΔV), and the resistance (R = ΔV / I) was calculated by dividing the measured change in voltage ΔV by the current I. The measurement results are shown in [Table 1] below.

[0213] Low-temperature resistance (Ω) Example 1174 Example 2168 Example 3164 Comparative Example 1266 Comparative Example 2194 Comparative Example 3215 Comparative Example 4227 Comparative Example 5255.1

[0214] Through Table 1 above, it can be confirmed that the low-temperature resistance of a lithium secondary battery using the positive active material of Examples 1 to 3, which has a coating layer including Nb and M formed thereon, is significantly lower than the low-temperature resistance of a lithium secondary battery using the positive active material of Comparative Examples 1 to 5.

Claims

A single-particle lithium nickel-based oxide comprising 1.50 or fewer nodules; and It comprises a coating layer formed on the above lithium nickel-based oxide and comprising a lithium metal oxide containing Nb and M, and The above M is a positive active material in which Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si.

2. In Paragraph 1, The above lithium metal oxide is a positive active material represented by the following [Chemical Formula 2]. [Chemical Formula 2] Li x No y M z O w In the above chemical formula 2, M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si; and 1≤x≤5, 1≤y≤40, 1≤z≤40, 1≤w≤35.

3. In Paragraph 1, The above lithium metal oxide is Li x Nb y Mg z O w, Li x Nb y Bi z O w, Li x Nb y Si z1 Mg z2 O w, Li x Nb y Si z1 Bi z3 O w, Li x Nb y Mg z2 Bi z3 O w, or Li x Nb y Si z1 Mg z2 Bi z3 O w A positive active material (where 1≤x≤5, 1≤y≤40, 1≤z≤40, 1≤w≤35, z1+z2+z3=z).

4. In Paragraph 1, A positive electrode active material comprising the lithium metal oxide in an amount of 100 ppm to 10,000 ppm based on the total weight of the positive electrode active material.

5. In Paragraph 1, The above single-particle lithium nickel-based oxide is a positive 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 ... comprises one or more elements 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.

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

7. In Paragraph 6, The above single-particle lithium nickel-based oxide is a positive 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 ... comprises one or more elements 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. A step of preparing a coating raw material by mixing an Nb-containing material, an M-containing material (wherein M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si) and a Li-containing material; and A method for manufacturing an anode active material comprising the step of mixing the above-mentioned coating raw material and a single-particle lithium nickel-based oxide and heat-treating to form a coating layer comprising a lithium metal oxide containing Nb and M on the lithium nickel-based oxide.

9. In Paragraph 8, A method for manufacturing a positive electrode active material, wherein the above Nb-containing material comprises Nb2O5, NbO2, NbF5, or a combination thereof.

10. In Paragraph 8, A method for manufacturing a positive electrode active material, wherein the above M-containing material comprises one or more selected from the group consisting of Mg(NO3)2, MgCO3, MgF2, MgO, MgSO4, Mg3N2, MgH6C4O4, Mg(OH)2, Bi, BiF3, Bi(NO3)3, Bi2O3, Bi(CH3CO2)3, and BiPO4.

11. In Paragraph 10, A method for manufacturing a positive electrode active material, wherein the above M-containing material further comprises one or more selected from the group consisting of SiC, Si3N4, SiO2, (OH)2SiO, Si(OH)4, Si, Si(OCOCH3)4, and Si(OC2H5)4.

12. In Paragraph 8, A method for manufacturing a positive electrode active material, wherein the above Li-containing material comprises LiH, LiNO3, Li2CO3, LiOH, LiH3C2O2, or a combination thereof.

13. In Paragraph 8, A method for manufacturing a positive electrode active material, wherein the above-mentioned coating raw material and the lithium nickel-based oxide are dry-mixed or wet-mixed.

14. In Paragraph 8, A method for manufacturing a positive electrode active material, wherein the above heat treatment is performed at 400°C to 1000°C for 3 to 12 hours.

15. In Paragraph 8, The step of preparing the above-mentioned coating raw material, A step of forming a mixture by mixing an Nb-containing material, an M-containing material (where M is Bi; Mg; a combination of Bi and Mg; a combination of Bi and Si; a combination of Mg and Si; or a combination of Bi, Mg and Si) and a Li-containing material; and A method for manufacturing an anode active material, comprising the step of pre-heat treating the above mixture to form a coating raw material.

16. In Paragraph 15, A method for manufacturing an anode active material, wherein the above-mentioned preheat treatment is performed at 400°C to 1000°C for 3 to 12 hours.

17. An anode comprising the anode active material of any one of claims 1 to 7.

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