Lithium transition metal oxide, a cathode additive for a lithium secondary battery, and a lithium secondary battery including the same

Abstract

The present invention relates to a lithium transition metal oxide, a positive electrode additive for a lithium secondary battery, and a lithium secondary battery including the same. According to the present invention, there is provided a lithium transition metal oxide that can suppress gas generation during charging and discharging of a lithium secondary battery by minimizing side reactions with an electrolyte.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application Nos. 10 - 2021 - 0009337 filed on January 22, 2021, 10 - 2021 - 0106774 filed on August 12, 2021, 10 - 2021 - 0106775 filed on August 12, 2021, and 10 - 2021 - 0106776 filed on August 12, 2021, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to a lithium transition metal oxide, a positive electrode additive for a lithium secondary battery, and a lithium secondary battery including the same.

Background Art

[0003] With the increasing multifunctionality of electronic devices and the consequent increase in power consumption, many attempts have been made to increase the capacity of lithium secondary batteries and improve their charge - discharge efficiency.

[0004] As an example, a technique has been proposed in which a positive electrode active material with 80% or more Ni is applied as a positive electrode material to the positive electrode of a lithium secondary battery, and a metal or metal - based negative electrode active material such as SiO, Si, or SiC is applied together with a carbon - based negative electrode active material such as natural graphite or artificial graphite to the negative electrode.

[0005] Metal and metal oxide - based negative electrode active materials enable the expression of higher capacity than carbon - based negative electrode active materials. However, since metal and metal oxide - based negative electrode active materials have a much larger volume change during charge - discharge than graphite, it is difficult to increase the content of metal and metal oxide in the negative electrode to 15% or more. Also, when metal and metal oxide are added to the negative electrode, an irreversible reaction occurs during the initial charge - discharge, and the loss of lithium is larger than when a carbon - based negative electrode active material is applied. Therefore, when a metal and metal oxide - based negative electrode active material is applied, the amount of lithium lost increases as the capacity of the battery increases, and the reduction in the initial capacity due to this also becomes larger.

[0006] Therefore, various solutions have been studied to increase the capacity of lithium secondary batteries or reduce the irreversible capacity. One of them is prelithiation, which is the concept of replenishing lithium consumed in the formation of the SEI layer (solid electrolyte interphase layer) in the initial state within the battery.

[0007] Various methods for prelithiation within the battery have been proposed.

[0008] As an example, there is a method of electrochemically lithiating the negative electrode in advance before driving the battery. However, the lithiated negative electrode is very unstable in the air, and it is difficult to scale up the process with the electrochemical lithiation method.

[0009] As another example, there is a method of coating the negative electrode with lithium metal or lithium silicide (Li x Si) powder. However, since the powder has high reactivity and reduced atmospheric stability, there is a problem that it is difficult to establish suitable solvents and process conditions during coating on the negative electrode.

[0010] As a method of prelithiation at the positive electrode, there is a method of further coating more positive electrode material by an amount equal to the amount of lithium consumed at the negative electrode. However, since the amount of the additional positive electrode material increases due to the low capacity of the positive electrode material itself, the energy density of the final battery and the capacity per unit weight will decrease by the amount of the increasing positive electrode material.

[0011] Therefore, the material suitable for pre-lithiation of the battery at the positive electrode must have the irreversible property that during the first charge, lithium desorbs at least twice or more as much as that of the existing positive electrode material and does not react with lithium during subsequent discharge. An additive that satisfies such conditions is called a sacrificial positive electrode material.

[0012] In the case of a commercial battery, after injecting an electrolyte into a case containing a stacked positive electrode, a separator, and a negative electrode, it undergoes a formation process in which a charge / discharge operation is first performed. In this process, a reaction occurs to form a SEI layer on the negative electrode, and gas is generated by the decomposition of the electrolyte. In the formation process, the sacrificial positive electrode material reacts with the electrolyte while releasing and decomposing lithium, and gases such as N2, O2, and CO2 generated in the process are recovered by a gas pocket removal process.

[0013] As the sacrificial positive electrode material, over-lithiated positive electrode materials of metal oxides rich in lithium are widely used. As the over-lithiated positive electrode materials, Li6CoO4, Li5FeO4, and Li6MnO4 having an anti-fluorite structure are well known. Their theoretical capacities are 977 mAh / g for Li6CoO4, 867 mAh / g for Li5FeO4, and 1001 mAh / g for Li6MnO4, and they have sufficient capacity to be used as sacrificial positive electrode materials. Among them, Li6CoO4 has the best electrical conductivity and good electrochemical properties for use as a sacrificial positive electrode material.

[0014] Li6CoO4 is gradually desorbed and decomposed during the formation process, causing the crystal phase to collapse, and O2 gas is inevitably generated in this process. Ideally, no additional gas should be generated during the charge-discharge cycles after the formation process. If continuous gas is generated during charge-discharge, the pressure inside the battery increases, the distance between the electrodes becomes farther, and the battery capacity and energy density decrease. In severe cases, the battery may not withstand the pressure and rupture, potentially leading to an explosion accident.

[0015] Therefore, there is a need to develop a technology that can inactivate or stabilize the final crystal phase of Li6CoO4 so that no additional gas is generated during the charge-discharge cycle.

Prior Art Documents

Patent Documents

[0016]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0017] The present invention provides a lithium transition metal oxide that can suppress side reactions with the electrolyte and mitigate gas generation at the positive electrode of a lithium secondary battery.

[0018] The present invention provides a method for manufacturing the lithium transition metal oxide.

[0019] The present invention provides a positive electrode additive for a lithium secondary battery containing the lithium transition metal oxide.

[0020] The present invention provides a positive electrode for a lithium secondary battery containing the transition metal oxide.

[0021] The present invention provides a positive electrode for a lithium secondary battery including the positive electrode additive for a lithium secondary battery. The present invention also provides a lithium secondary battery including the positive electrode for a secondary battery.

Means for Solving the Problem

[0022] According to an embodiment of the present invention, a lithium cobalt oxide containing a hetero element, the hetero element includes a Group 4 transition metal, and further includes one or more selected from the group consisting of a Group 2 element, a Group 13 element, a Group 14 element, a Group 5 transition metal, and a Group 6 transition metal, and a lithium transition metal oxide is provided.

[0023] According to another embodiment of the present invention, a first step of solid-phase mixing a lithium oxide, a cobalt oxide, and a hetero element oxide; a second step of firing the mixture obtained in the first step in an inert atmosphere at a temperature of 550°C to 750°C to obtain the lithium transition metal oxide, and a method for producing the lithium transition metal oxide is provided.

[0024] According to still another embodiment of the present invention, a positive electrode additive for a lithium secondary battery including the lithium transition metal oxide is provided.

[0025] According to still another embodiment of the present invention, a positive electrode for a lithium secondary battery including a positive electrode active material, a binder, a conductive material, and the lithium transition metal oxide is provided.

[0026] According to still another embodiment of the present invention, a positive electrode for a lithium secondary battery including a positive electrode active material, a binder, a conductive material, and the positive electrode additive for a lithium secondary battery is provided.

[0027] According to still another embodiment of the present invention, A lithium secondary battery is provided, which includes the positive electrode for the lithium secondary battery, a negative electrode, a separator, and an electrolyte.

[0028] Hereinafter, the lithium transition metal oxide, the method for manufacturing the lithium transition metal oxide, the positive electrode additive for the lithium secondary battery, the positive electrode for the lithium secondary battery, and the lithium secondary battery according to the embodiments of the invention will be described in more detail.

[0029] The terms and words used in this specification and the claims should not be construed as being limited to ordinary or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best way, they should be construed as meanings and concepts that conform to the technical idea of the present invention.

[0030] Unless otherwise specifically defined in this specification, all technical terms and scientific terms have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. The terms used in the description of the present invention are merely used to effectively describe specific examples and are not intended to limit the present invention.

[0031] As used in this specification, the singular form also includes the plural form unless the context clearly indicates the contrary meaning.

[0032] As used in this specification, the meaning of "including" does not exclude the presence or addition of other specific characteristics, regions, integers, steps, operations, elements, components, and / or groups while embodying a specific characteristic, region, integer, step, operation, element, and / or component.

[0033] Since the present invention can be modified in various ways and can have various forms, specific examples will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood to include all modifications, equivalents, or alternatives included in the spirit and technical scope of the present invention.

[0034] In this specification, for example, when the positional relationship between two parts such as "on ~", "above ~", "below ~", "on the side of ~" is described, unless the expressions "immediately" or "directly" are used, one or more other parts may be located between the two parts.

[0035] In this specification, for example, when the temporal sequence relationship such as "after ~", "subsequent to ~", "next to ~", "before ~" is described, unless the expressions "immediately" or "directly" are used, it may also include cases where it is not continuous.

[0036] The term "at least one" in this specification should be understood to include all combinations that can be presented from one or more related items.

[0037] As used herein, the term "positive electrode additive" means a substance having an irreversible characteristic in which lithium during the initial charging of the battery desorbs at least twice as much as the existing positive electrode material and then does not react with lithium during discharge. The positive electrode additive can also be referred to as sacrificial positive electrode materials. Since the positive electrode additive compensates for lithium loss, as a result, the lost capacity of the battery is recovered, the capacity of the battery increases, and by suppressing gas generation, it is possible to prevent the battery from exploding and improve the life characteristics and safety of the battery.

[0038] As used herein, the term "stabilization of the crystal phase" means suppressing the oxidizing property of amorphous CoO2 that occurs after the initial charging of a lithium secondary battery including a lithium cobalt oxide-based positive electrode additive into which a foreign element has been introduced. By suppressing the oxidizing property of the amorphous CoO2, it is possible to prevent the side reaction between CoO2 and the electrolyte and suppress gas generation.

[0039] I. Lithium transition metal oxide According to an embodiment of the present invention, a lithium cobalt oxide containing a foreign element, The heterogeneous elements include transition metals of the fourth period, and further include one or more selected from the group consisting of group 2 elements, group 13 elements, group 14 elements, transition metals of the fifth period, and transition metals of the sixth period, and a lithium transition metal oxide is provided.

[0040] As a result of the continuous research of the present inventors, it has been confirmed that a lithium transition metal oxide into which two or more heterogeneous elements satisfying such a composition are introduced can minimize the side reaction with the electrolyte and suppress gas generation at the positive electrode during charge and discharge of the lithium secondary battery, and can ensure excellent battery performance. It is expected that this is because a more stable crystal phase is maintained by introducing two or more heterogeneous elements satisfying the composition into the lithium transition metal oxide, and the decrease in the initial charge capacity is minimized. Therefore, the lithium transition metal oxide can improve the safety and life characteristics of the lithium secondary battery.

[0041] By including two or more heterogeneous elements satisfying the above composition, the lithium transition metal oxide can stabilize the crystal phase compared to lithium cobalt oxides such as Li6CoO4. In the present invention, the stabilization of the crystal phase means suppressing the oxidizing property of amorphous CoO2 formed after the initial charge of the lithium secondary battery containing the lithium cobalt oxide.

[0042] In this connection, after a lithium secondary battery containing Li6CoO4 is fully charged and the crystal phase of the electrode is confirmed by X-ray diffraction (XRD), there is a tendency that there is no amorphous pattern. In the formation process, Li6CoO4 is initially Co 2+ The cation is oxidized to Co 4+ The cation, and then gas is generated by oxidizing the O 2- Anion. When charging is completed, it becomes the composition of CoO2 (Co 4+ ), but since it does not show crystallinity in the above composition, no pattern is observed.

[0043] Co 4+In the case of cations, leave them as they are or Co during discharge (reduction reaction). 2+ Cations or Co 3+ Since the oxidizing property of cations that tend to be reduced is strong, the surrounding electrolyte is oxidized and side reactions occur. Due to the side reactions, electrolytes such as carbonates decompose, and gases such as CO2, CO, and H2 are generated. After that, when charge-discharge cycles are performed, Co reduced during charging 2+ Cations or Co 3+ Cations become Co 4+ Cations are oxidized to Co, and during discharge, Co becomes 4+ Cations become Co 2+ Cations or Co 3+ Cations are reduced, and gases are continuously generated due to the side reactions.

[0044] To suppress such side reactions, it is necessary to suppress the oxidizing property of Co 4+ cations that tend to be reduced. For example, a method of introducing a different element to stabilize the oxidation number of Co 4+ cations can be mentioned.

[0045] In the lithium transition metal oxide, by introducing a different element having a fixed oxidation number during charge and discharge of the battery, an effect of lowering the average oxidation number of Co 4+ cations can be expected. Therefore, Co 4+ the oxidizing property of cations is suppressed, and the generation of gas due to the side reactions is suppressed.

[0046] However, as the introduction amount of the different element having a fixed oxidation number during charge and discharge of the battery increases, the initial charge capacity relatively decreases, and the electrical conductivity tends to decrease. Therefore, by introducing a fourth-period transition metal as the main element of the different element and introducing a secondary element that can complement the electrochemical properties of the main element together, the stabilizing effect of the crystal phase can be expressed, and excellent battery performance can be ensured.

[0047] The lithium transition metal oxide has a composition in which two or more different elements are introduced by alloying or doping into Li6CoO4.

[0048] Here, the "alloy" means a lithium transition metal oxide in which the hetero element is introduced at 10 mol% or more based on the total metal elements excluding lithium. And the "doping" means a lithium transition metal oxide in which the hetero element is introduced at less than 10 mol% based on the total metal elements excluding lithium.

[0049] The lithium transition metal compound contains a Group 4 transition metal as a main element among the hetero elements.

[0050] And the lithium transition metal compound contains at least one element selected from the group consisting of a Group 2 element, a Group 13 element, a Group 14 element, a Group 5 transition metal, and a Group 6 transition metal as a sub-element among the hetero elements.

[0051] Specifically, the Group 4 transition metal contains at least one selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.

[0052] And the Group 2 element contains at least one selected from the group consisting of Mg, Ca, Sr, and Ba; the Group 13 element contains at least one selected from the group consisting of Al, Ga, and In; the Group 14 element contains at least one selected from the group consisting of Si, Ge, and Sn; the Group 5 transition metal contains at least one selected from the group consisting of Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, and Cd; the Group 6 transition metal contains at least one selected from the group consisting of Lu, Hf, Ta, W, Re, Os, Ir, Pt, and Au.

[0053] Preferably, from the aspects of ease of alloying or doping with lithium cobalt oxide and stabilization of the crystal phase, it can contain Zn, which is a Group 4 transition metal, as the main element among the hetero elements, and can contain at least one element selected from the group consisting of Al, Mg, Ti, Zr, Nb, and W as the sub-element.

[0054] Zn, Al, Mg, Ti, Zr, Nb, and W are often substituted for Co sites in the anti-fluorite lattice structure of the crystal phase of Li6CoO4 and have the property that their oxidation numbers remain unchanged. For example, since there exists a Li6ZnO4 crystal phase and an alloy with Li6CoO4 is also easily formed, and its oxidation number also remains 2+, Co 4+ cation oxidation can be effectively suppressed after initial charging.

[0055] The heteroelements are selected considering whether they exist within the anti-fluorite lattice structure of lithium cobalt oxide and whether they have a fixed oxidation number during charge and discharge of the battery.

[0056] As an example, among the Group 4 transition metals, since there exists a Li6ZnO4 crystal phase and an alloy with Li6CoO4 is also easily formed, and its oxidation number also remains 2+, Co 4+ cation oxidation can be effectively suppressed after initial charging.

[0057] As another example, in the case of Li5FeO4 and Li6MnO4 that do not satisfy the composition, an anti-fluorite lattice structure can be formed. However, Mn has multiple oxidation numbers of 2+, 3+, 4+, and 7+, and Fe has multiple oxidation numbers of 2+ and 3+. Therefore, when raw materials such as CoO, MnO, and Fe2O3 of the lithium cobalt oxide are mixed and then calcined, Mn or Fe is oxidized, and Co 2+ cation is reduced to form Co metal rather than a single-crystal-phase anti-fluorite lattice structure. 0 Even if a single-crystal-phase alloyed Li6CoO4 is formed, in the case of Mn or Fe, since the oxidation number easily changes within the operating voltage, it is difficult to suppress the oxidation of Co 4+ cation after initial charging.

[0058] In the lithium transition metal oxide, the hetero element is contained in an amount of 5 mol% to 80 mol% based on the total amount of metal elements excluding lithium.

[0059] In order to exhibit the stabilizing effect on the crystal phase, the content of the hetero element is preferably 5 mol% or more based on the total amount of metal elements excluding lithium. However, when an excessive amount of the hetero element is introduced, the electric conductivity of the lithium transition metal oxide decreases, the resistance of the electrode increases, and the performance of the battery deteriorates. Therefore, the content of the hetero element is preferably 80 mol% or less based on the total amount of metal elements excluding lithium.

[0060] Specifically, the content of the hetero element can be 5 mol% or more, or 10 mol% or more, or 15 mol% or more; and 80 mol% or less, or 70 mol% or less, or 60 mol% or less based on the total amount of metal elements excluding lithium.

[0061] Preferably, the content of the hetero element can be 10 mol% to 80 mol%, or 10 mol% to 70 mol%, or 15 mol% to 70 mol%, or 15 mol% to 60 mol% based on the total amount of metal elements excluding lithium.

[0062] Furthermore, within the range of the content of the hetero element, the content ratio of the main element (the fourth-period transition metal) and the sub element (one or more elements selected from the group consisting of the second-group element, the thirteenth-group element, the fourteenth-group element, the fifth-period transition metal, and the sixth-period transition metal) is determined.

[0063] As an example, the fourth-period transition metal in the hetero element is contained in an amount of 10 mol% to 70 mol% based on the total amount of metal elements excluding lithium in the lithium transition metal oxide.

[0064] In order to exhibit the stabilizing effect on the crystal phase, the content of the Group 4 transition metal in the lithium transition metal oxide is preferably 10 mol% or more based on the total metal elements excluding lithium. However, when an excessive amount of foreign elements is introduced, the electric conductivity of the lithium transition metal oxide decreases, the resistance of the electrode increases, and the performance of the battery deteriorates. Therefore, the content of the Group 4 transition metal in the lithium transition metal oxide is preferably 70 mol% or less based on the total metal elements excluding lithium.

[0065] Specifically, the content of the Group 4 transition metal in the lithium transition metal oxide can be 10 mol% or more, or 15 mol% or more, or 20 mol% or more; and 70 mol% or less, or 50 mol% or less, or 30 mol% or less based on the total metal elements excluding lithium.

[0066] Preferably, the content of the Group 4 transition metal in the lithium transition metal oxide can be 10 mol% to 70 mol%, or 15 mol% to 70 mol%, or 15 mol% to 50 mol%, or 20 mol% to 50 mol%, or 20 mol% to 30 mol% based on the total metal elements excluding lithium.

[0067] The stabilizing effect on the crystal phase of the lithium transition metal oxide is expected to be proportional to the content of the foreign elements. However, it can be shown that as the introduction amount of foreign elements such as Zn, which is electrochemically inactive, increases, the initial charge capacity relatively decreases and the electric conductivity tends to decrease.

[0068] Therefore, the content of the secondary element in the foreign elements is preferably 1 mol% or more based on the total metal elements excluding lithium.

[0069] However, when excessive foreign elements are introduced, the electrical conductivity of the lithium transition metal oxide decreases, the resistance of the electrode increases, and the performance of the battery deteriorates. Therefore, the content of the sub-element in the lithium transition metal oxide is preferably 20 mol% or less based on the total metal elements excluding lithium.

[0070] Specifically, the content of the sub-element in the lithium transition metal oxide can be 1 mol% or more, or 2 mol% or more, or 3 mol% or more; and 20 mol% or less, or 17 mol% or less, or 15 mol% or less based on the total metal elements excluding lithium.

[0071] Preferably, the content of the sub-element in the lithium transition metal oxide can be 1 mol% - 20 mol%, or 2 mol% - 20 mol%, or 2 mol% - 17 mol%, or 3 mol% - 17 mol%, or 3 mol% - 15 mol% based on the total metal elements excluding lithium.

[0072] The lithium transition metal oxide is represented by the following Chemical Formula 1: [Chemical Formula 1] Li6Co 1-x-y Zn x M y O4 In the Chemical Formula 1, M is a Group 2 element, a Group 13 element, a Group 14 element, a Group 5 transition metal, or a Group 6 transition metal, x is 0.1 - 0.7, y is 0.01 - 0.2.

[0073] Preferably, in the Chemical Formula 1, M can be one or more elements selected from the group consisting of Al, Mg, Ti, Zr, Nb, and W.

[0074] In the Chemical Formula 1, x is 0.1 - 0.7 and y is 0.01 - 0.2.

[0075] Specifically, the x can be 0.1 or more, or 0.15 or more, or 0.2 or more; and 0.7 or less, or 0.5 or less, or 0.3 or less. Preferably, the x can be 0.1 to 0.7, or 0.15 to 0.7, or 0.15 to 0.5, or 0.2 to 0.5, or 0.2 to 0.3.

[0076] The y can be 0.01 or more, or 0.02 or more, or 0.03 or more; and 0.2 or less, or 0.17 or less, or 0.15 or less. Preferably, the y can be 0.01 to 0.2, or 0.02 to 0.2, or 0.02 to 0.17, or 0.03 to 0.17, or 0.03 to 0.15.

[0077] And in the Chemical Formula 1, the value of x + y is preferably 0.05 or more, or 0.10 or more, or 0.15 or more, or 0.20 or more; and 0.80 or less, or 0.70 or less, or 0.60 or less, or 0.50 or less.

[0078] That is, for the expression of the crystal phase stabilization effect of the lithium transition metal oxide, in the Chemical Formula 1, the value of x + y is preferably 0.05 or more, or 0.10 or more, or 0.15 or more, or 0.20 or more. However, when the value of x + y is too large, the electric conductivity of the lithium transition metal oxide may decrease and the performance of the battery may deteriorate. Therefore, in the Chemical Formula 1, the value of x + y is preferably 0.80 or less, or 0.70 or less, or 0.60 or less, or 0.50 or less.

[0079] Specifically, in the Chemical Formula 1, the value of x + y can be 0.05 to 0.80, or 0.10 to 0.80, or 0.15 to 0.80, or 0.15 to 0.70, or 0.15 to 0.60, or 0.20 to 0.60, or 0.20 to 0.50.

[0080] Preferably, the lithium transition metal oxide is Li6Co 0.77 Zn 0.2 Al0.03 O4, Li6Co 0.76 Zn 0.2 Al 0.04 O4, Li6Co 0.75 Zn 0.2 Al 0.05 O4, Li6Co 0.7 Zn 0.25 Al 0.05 O4, Li6Co 0.65 Zn 0.25 Al 0.1 O4, Li6Co 0.67 Zn 0.3 Al 0.03 O4, Li6Co 0.66 Zn 0.3 Al 0.04 O4, Li6Co 0.65 Zn 0.3 Al 0.05 O4, Li6Co 0.6 Zn 0.3 Al 0.1 O4, Li6Co 0.77 Zn 0.2 Mg 0.03 O4, Li6Co 0.76 Zn 0.2 Mg 0.04 O4, Li6Co 0.75 Zn 0.2 Mg 0.05 O4, Li6Co 0.7 Zn 0.25 Mg 0.05 O4, Li6Co 0.67 Zn 0.3 Mg 0.03 O4, Li6Co 0.66 Zn 0.3 Mg 0.04 O4, Li6Co 0.65 Zn 0.3 Mg 0.05 O4, Li6Co 0.77 Zn 0.2 Ti 0.03 O4, Li6Co 0.76 Zn 0.2 Ti 0.04 O4, Li6Co 0.75 Zn 0.2 Ti 0.05 O4, Li6Co 0.72 Zn 0.25 Ti 0.03 O4, Li6Co 0.67Zn 0.3 Ti 0.03 O4, Li6Co 0.66 Zn 0.3 Ti 0.04 O4, Li6Co 0.65 Zn 0.3 Ti 0.05 O4, Li6Co 0.77 Zn 0.2 Zr 0.03 O4, Li6Co 0.76 Zn 0.2 Zr 0.04 O4, Li6Co 0.75 Zn 0.2 Zr 0.05 O4, Li6Co 0.72 Zn 0.25 Zr 0.03 O4, Li6Co 0.67 Zn 0.3 Zr 0.03 O4, Li6Co 0.66 Zn 0.3 Zr 0.04 O4, Li6Co 0.65 Zn 0.3 Zr 0.05 O4, Li6Co 0.77 Zn 0.2 Nb 0.03 O4, Li6Co 0.76 Zn 0.2 Nb 0.04 O4, Li6Co 0.75 Zn 0.2 Nb 0.05 O4, Li6Co 0.67 Zn 0.3 Nb 0.03 O4, Li6Co 0.66 Zn 0.3 Nb 0.04 O4, Li6Co 0.65 Zn 0.3 Nb 0.05 O4, Li6Co 0.77 Zn 0.2 W 0.03 O4, Li6Co 0.76 Zn 0.2 W 0.04 O4, Li6Co 0.75 Zn 0.2 W 0.05 O4, Li6Co 0.67 Zn 0.3 W 0.03O4, Li6Co 0.66 Zn 0.3 W 0.04 O4, and Li6Co 0.65 Zn 0.3 W 0.05 It may contain one or more compounds selected from the group consisting of O4.

[0081] The lithium transition metal oxide has the property of irreversibly releasing lithium during charge and discharge of a lithium secondary battery. In particular, the side reaction between the lithium transition metal oxide and the electrolyte is suppressed, enabling improvement in the safety and life characteristics of the lithium secondary battery.

[0082] II. Method for Producing Lithium Transition Metal Oxide According to another embodiment of the present invention, a first step of solid-phase mixing a lithium oxide, a cobalt oxide, and a heterogeneous element oxide; a second step of firing the mixture obtained in the first step in an inert atmosphere at a temperature of 550°C to 750°C to obtain the lithium transition metal oxide, and a method for producing the lithium transition metal oxide is provided.

[0083] In the first step, a raw material mixture containing a lithium oxide, a cobalt oxide, and a heterogeneous element oxide is prepared.

[0084] As the lithium oxide, an oxide containing lithium such as Li2O can be used without particular limitation.

[0085] Also, as the cobalt oxide, an oxide containing cobalt such as CoO can be used without particular limitation.

[0086] Regarding the matters related to the heterogeneous element, the content described in the item of "I. Lithium Transition Metal Oxide" is substituted.

[0087] As the heterogeneous element oxide, oxides of transition metals in the fourth period, and oxides of one or more elements selected from the group consisting of Group 2 elements, Group 13 elements, Group 14 elements, transition metals in the fifth period, and transition metals in the sixth period can be used. As non-limiting examples, as the heterogeneous element oxide, oxides containing the above heterogeneous elements such as ZnO, Mg, Al2O3, TiO2, ZrO2, Nb2O2, and WO3 can be used without particular limitation.

[0088] The raw material mixture is prepared by solid-phase mixing the lithium oxide, the cobalt oxide, and the heterogeneous element oxide in accordance with the stoichiometric ratio described in the item of "I. Lithium transition metal oxide".

[0089] In the second step, the lithium transition metal oxide is obtained by firing the raw material mixture obtained in the first step at a temperature of 550 °C to 750 °C in an inert atmosphere.

[0090] The second step is carried out in an inert atmosphere formed using an inert gas such as Ar, N2, Ne, and He.

[0091] In the second step, it is preferable to heat the mixture obtained in the first step at a heating rate of 1.4 °C / min to 2.0 °C / min in an inert atmosphere to reach the firing temperature.

[0092] When the heating rate is excessively slow, crystal seeds are gradually formed, crystal growth continues, and the particles become excessively large. Therefore, the heating rate is preferably 1.4 °C / min or more. However, when the heating rate is too fast, a large amount of crystal seeds are generated at a very high speed, the growth time of the particles is relatively insufficient, the crystallinity becomes relatively low, and the size of the particles also becomes relatively small. Therefore, the heating rate is preferably 2.0 °C / min or less.

[0093] Specifically, the heating rate can be 1.40 °C / min or more, or 1.45 °C / min or more, or 1.50 °C / min or more; and 2.00 °C / min or less, or 1.95 °C / min or less, or 1.90 °C / min or less. Preferably, the heating rate can be 1.40 °C / min to 2.00 °C / min, or 1.45 °C / min to 2.00 °C / min, or 1.45 °C / min to 1.95 °C / min, or 1.50 °C / min to 1.95 °C / min, or 1.50 °C / min to 1.90 °C / min.

[0094] The firing is performed at a temperature of 550 °C to 750 °C.

[0095] To generate crystal seeds at an appropriate rate, the firing temperature is preferably 550 °C or higher. However, if the firing temperature is too high, a sintering phenomenon occurs where the grown crystal particles solidify. Therefore, the firing temperature is preferably 750 °C or lower.

[0096] Specifically, the firing temperature can be 550 °C or more, or 580 °C or more, or 600 °C or more; and 750 °C or less, or 720 °C or less, or 700 °C or less. Preferably, the firing temperature can be 580 °C to 750 °C, or 580 °C to 720 °C, or 600 °C to 720 °C, or 600 °C to 700 °C.

[0097] The firing is performed for 2 hours to 20 hours at the firing temperature. The firing time can be adjusted in consideration of the time required for foreign elements to be introduced into lithium cobalt oxide in the form of an alloy or doping to stabilize the crystal. Specifically, the firing time can be 2 hours or more, or 3 hours or more, or 4 hours or more; and 20 hours or less, or 19 hours or less, or 18 hours or less. Preferably, the firing time can be 3 hours to 20 hours, or 3 hours to 19 hours, or 4 hours to 19 hours, or 4 hours to 18 hours.

[0098] The lithium transition metal oxide obtained in the second stage has a cumulative 50% particle size (D50) of 1 μm to 30 μm as measured by laser diffraction scattering particle size distribution measurement. If necessary, a step of pulverizing and classifying the lithium transition metal oxide so as to fall within the range of the D50 value can be performed.

[0099] In order to prevent the side reaction with the electrolyte from intensifying due to a very large specific surface area, the D50 value is preferably 1 μm or more. However, if the particle size is too large, it is difficult to uniformly coat the positive electrode material containing the lithium transition metal oxide on the current collector, and damage to the current collector can be induced during the rolling process after drying. Therefore, the D50 value is preferably 30 μm or less.

[0100] Specifically, the lithium transition metal oxide has a D50 value of 1 μm or more, or 3 μm or more, or 5 μm or more; and 30 μm or less, or 27 μm or less, or 25 μm or less. Preferably, the lithium transition metal oxide has a D50 value of 3 μm to 30 μm, or 3 μm to 27 μm, or 5 μm to 27 μm, or 5 μm to 25 μm.

[0101] If necessary, a step of washing and drying the compound represented by Chemical Formula 1 obtained in the second stage can be performed.

[0102] As a non-limiting example, the washing step can be performed by mixing the compound of Chemical Formula 1 and the washing liquid at a weight ratio of 1:2 to 1:10 and stirring. As the washing liquid, distilled water, aqueous ammonia, etc. can be used. The drying can be performed by heat treatment at a temperature of 100 °C to 200 °C or 100 °C to 180 °C for 1 hour to 10 hours.

[0103] III. Positive Electrode Additive for Lithium Secondary Battery According to another embodiment of the present invention, a positive electrode additive for a lithium secondary battery containing the lithium transition metal oxide is provided.

[0104] The lithium transition metal oxide can minimize side reactions with the electrolyte and suppress gas generation at the positive electrode during charge and discharge of the lithium secondary battery. Therefore, the positive electrode additive for a lithium secondary battery containing the lithium transition metal oxide enables improvement in the safety and life characteristics of the lithium secondary battery.

[0105] The positive electrode additive for a lithium secondary battery containing the lithium transition metal oxide has the property of irreversibly releasing lithium during charge and discharge of the lithium secondary battery. Therefore, the positive electrode additive for a lithium secondary battery is included in the positive electrode for a lithium secondary battery and can serve as sacrificial positive electrode materials for prelithiation.

[0106] Matters regarding the lithium transition metal oxide are replaced with the content described in the item of "I. Lithium transition metal oxide".

[0107] The lithium transition metal oxide has a composition in which two or more different elements are alloyed or doped into Li6CoO4 and introduced.

[0108] The lithium transition metal compound contains a fourth-period transition metal as a main element among the different elements.

[0109] And the lithium transition metal compound contains one or more elements selected from the group consisting of a group 2 element, a group 13 element, a group 14 element, a fifth-period transition metal, and a sixth-period transition metal as secondary elements among the different elements.

[0110] Specifically, the fourth-period transition metal contains one or more selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.

[0111] The Group 2 element includes one or more selected from the group consisting of Mg, Ca, Sr, and Ba; the Group 13 element includes one or more selected from the group consisting of Al, Ga, and In; the Group 14 element includes one or more selected from the group consisting of Si, Ge, and Sn; the Group 5 transition metal includes one or more selected from the group consisting of Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, and Cd; and the Group 6 transition metal includes one or more selected from the group consisting of Lu, Hf, Ta, W, Re, Os, Ir, Pt, and Au.

[0112] Preferably, from the aspects of the ease of alloying or doping with lithium cobalt oxide and the stabilization of the crystal phase, Zn, which is a Group 4 transition metal, can be included as the main element among the heterogeneous elements, and one or more elements selected from the group consisting of Al, Mg, Ti, Zr, Nb, and W can be included as the sub-elements.

[0113] The heterogeneous elements are included in an amount of 5 mol% to 80 mol% based on the total metal elements excluding lithium in the lithium transition metal oxide.

[0114] The Group 4 transition metal among the heterogeneous elements is included in an amount of 10 mol% to 70 mol% based on the total metal elements excluding lithium in the lithium transition metal oxide.

[0115] One or more heterogeneous elements selected from the group consisting of the Group 2 element, the Group 13 element, the Group 14 element, the Group 5 transition metal, and the Group 6 transition metal among the heterogeneous elements are included in an amount of 1 mol% to 20 mol% based on the total metal elements excluding lithium in the lithium transition metal oxide.

[0116] The lithium transition metal oxide is represented by the following Chemical Formula 1: [Chemical Formula 1] Li6Co 1-x-y Zn x M y O4 In Chemical Formula 1, M is a Group 2 element, a Group 13 element, a Group 14 element, a Period 5 transition metal, or a Period 6 transition metal, x is from 0.1 to 0.7, y is from 0.01 to 0.2.

[0117] Preferably, in the chemical formula 1, M can be one or more elements selected from the group consisting of Al, Mg, Ti, Zr, Nb, and W.

[0118] Preferably, the lithium transition metal oxide is Li6Co 0.77 Zn 0.2 Al 0.03 O4, Li6Co 0.76 Zn 0.2 Al 0.04 O4, Li6Co 0.75 Zn 0.2 Al 0.05 O4, Li6Co 0.7 Zn 0.25 Al 0.05 O4, Li6Co 0.65 Zn 0.25 Al 0.1 O4, Li6Co 0.67 Zn 0.3 Al 0.03 O4, Li6Co 0.66 Zn 0.3 Al 0.04 O4, Li6Co 0.65 Zn 0.3 Al 0.05 O4, Li6Co 0.6 Zn 0.3 Al 0.1 O4, Li6Co 0.77 Zn 0.2 Mg 0.03 O4, Li6Co 0.76 Zn 0.2 Mg 0.04 O4, Li6Co 0.75 Zn 0.2 Mg 0.05 O4, Li6Co 0.7 Zn 0.25 Mg 0.05 O4, Li6Co 0.67 Zn 0.3 Mg 0.03 O4, Li6Co 0.66 Zn0.3 Mg 0.04 O4, Li6Co 0.65 Zn 0.3 Mg 0.05 O4, Li6Co 0.77 Zn 0.2 Ti 0.03 O4, Li6Co 0.76 Zn 0.2 Ti 0.04 O4, Li6Co 0.75 Zn 0.2 Ti 0.05 O4, Li6Co 0.72 Zn 0.25 Ti 0.03 O4, Li6Co 0.67 Zn 0.3 Ti 0.03 O4, Li6Co 0.66 Zn 0.3 Ti 0.04 O4, Li6Co 0.65 Zn 0.3 Ti 0.05 O4, Li6Co 0.77 Zn 0.2 Zr 0.03 O4, Li6Co 0.76 Zn 0.2 Zr 0.04 O4, Li6Co 0.75 Zn 0.2 Zr 0.05 O4, Li6Co 0.72 Zn 0.25 Zr 0.03 O4, Li6Co 0.67 Zn 0.3 Zr 0.03 O4, Li6Co 0.66 Zn 0.3 Zr 0.04 O4, Li6Co 0.65 Zn 0.3 Zr 0.05 O4, Li6Co 0.77 Zn 0.2 Nb 0.03 O4, Li6Co 0.76 Zn 0.2 Nb 0.04 O4, Li6Co 0.75 Zn 0.2 Nb 0.05 O4, Li6Co 0.67 Zn 0.3 Nb 0.03O4, Li6Co 0.66 Zn 0.3 Nb 0.04 O4, Li6Co 0.65 Zn 0.3 Nb 0.05 O4, Li6Co 0.77 Zn 0.2 W 0.03 O4, Li6Co 0.76 Zn 0.2 W 0.04 O4, Li6Co 0.75 Zn 0.2 W 0.05 O4, Li6Co 0.67 Zn 0.3 W 0.03 O4, Li6Co 0.66 Zn 0.3 W 0.04 O4 and Li6Co 0.65 Zn 0.3 W 0.05 It may contain one or more compounds selected from the group consisting of O4.

[0119] IV. Cathode for Lithium Secondary Battery According to another embodiment of the present invention, a cathode for a lithium secondary battery is provided.

[0120] The cathode for the lithium secondary battery may include a cathode active material, a binder, a conductive material, and the lithium transition metal oxide.

[0121] Also, the cathode for the lithium secondary battery may include a cathode active material, a binder, a conductive material, and the additive for the cathode of the lithium secondary battery.

[0122] The lithium transition metal oxide and the additive for the cathode of the lithium secondary battery have the property of irreversibly releasing lithium during charge and discharge of the lithium secondary battery. Therefore, the lithium transition metal oxide and the additive for the cathode of the lithium secondary battery are included in the cathode for the lithium secondary battery and can serve as sacrificial positive electrode materials for prelithiation.

[0123] Preferably, the positive electrode for the lithium secondary battery includes a positive electrode active material, a conductive material, the sacrificial anode material, and a positive electrode material including a binder, and a current collector that supports the positive electrode material.

[0124] Here, the sacrificial anode material is the lithium transition metal oxide or the additive for the positive electrode of the lithium secondary battery. Matters regarding the sacrificial anode material are replaced with the contents described in the items of "I. Lithium transition metal oxide" and "III. Additive for the positive electrode of the lithium secondary battery".

[0125] In order to increase the battery capacity as the battery goes to a high-capacity battery, the ratio of the negative electrode active material in the negative electrode must be further increased, and thereby, the amount of lithium consumed in the SEI layer also increases accordingly. Therefore, after calculating the amount of lithium consumed in the SEI layer of the negative electrode, the amount of the sacrificial anode material applied to the positive electrode side can be calculated backward to determine the design capacity of the battery.

[0126] According to one embodiment, the sacrificial anode material is contained in an amount of more than 0% by weight and 15% by weight or less based on the total weight of the positive electrode material.

[0127] In order to compensate for the irreversible lithium consumed in the formation of the SEI layer, the content of the sacrificial anode material is preferably more than 0% by weight based on the total weight of the positive electrode material.

[0128] However, when the sacrificial anode material is contained in excess, the content of the positive electrode active material showing a reversible charge-discharge capacity decreases, the capacity of the battery decreases, and the remaining lithium in the battery is plated on the negative electrode, inducing a short circuit of the battery or inhibiting safety. Therefore, the content of the sacrificial anode material is preferably 15% by weight or less based on the total weight of the positive electrode material.

[0129] Specifically, the content of the sacrificial anode material may be more than 0% by weight, or 0.5% by weight or more, or 1% by weight or more, or 2% by weight or more, or 3% by weight or more with respect to the total weight of the positive electrode material; and may be 15% by weight or less, or 12% by weight or less, or 10% by weight or less.

[0130] Preferably, the content of the sacrificial anode material may be 0.5% by weight to 15% by weight, or 1% by weight to 15% by weight, or 1% by weight to 12% by weight, or 2% by weight to 12% by weight, or 2% by weight to 10% by weight, or 3% by weight to 10% by weight with respect to the total weight of the positive electrode material.

[0131] As the positive electrode active material, any compound applicable to a lithium secondary battery in the technical field to which the present invention pertains can be used without particular limitation.

[0132] As non-limiting examples, the positive electrode active material may be NCM (Li[Ni, Co, Mn]O2), NCMA (Li[Ni, Co, Mn, Al]O2), LiCoO2, LiNiO2, LiMnO2, LiMn2O2, LiNi 1-d Co d O2, LiCo 1-d Mn d O2, LiNi 1-d Mn d O2 (where 0 ≦ d < 1), Li(Ni a Co b Mn c )O4 (0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), LiMn 2-e Ni e O4, LiMn 2-e Co e O4 (where 0 < e < 2), LiCoPO4, and LiFePO4, etc. As the positive electrode active material, one or a mixture of two or more of the above examples can be used.

[0133] According to one embodiment, the positive electrode active material is contained in an amount of 80% by weight to 95% by weight with respect to the total weight of the positive electrode material.

[0134] Specifically, the content of the positive electrode active material can be 80% by weight or more, or 82% by weight or more, or 85% by weight or more with respect to the total weight of the positive electrode material; and 95% by weight or less, or 93% by weight or less, or 90% by weight or less.

[0135] Preferably, the content of the positive electrode active material can be 82% to 95% by weight, or 82% to 93% by weight, or 85% to 93% by weight, or 85% to 90% by weight with respect to the total weight of the positive electrode material.

[0136] The conductive material is used to impart conductivity to the electrode.

[0137] As the conductive material, any material that does not cause a chemical change in the battery and has electron conductivity can be used without particular limitation. As non-limiting examples, the conductive material can be carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber; graphite such as natural graphite and artificial graphite; metal powders or metal fibers such as copper, nickel, aluminum, silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. As the conductive material, one or a mixture of two or more of the above examples can be used.

[0138] The content of the conductive material is adjusted within a range that does not induce a decrease in the battery capacity while exhibiting an appropriate level of conductivity. Preferably, the content of the conductive material can be 1% to 10% by weight or 1% to 5% by weight with respect to the total weight of the positive electrode material.

[0139] The binder is used to adhere the positive electrode material well to the current collector.

[0140] As a non-limiting example, the binder may be polyvinylidene fluoride (PVdF), vinylidene fluoride - hexafluoropropylene copolymer (PVdF - co - HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene - propylene - diene polymer (EPDM), sulfonated EPDM, styrene - butadiene rubber (SBR), fluororubber, etc. As the binder, one or a mixture of two or more of the above examples can be used.

[0141] The content of the binder is adjusted within a range that does not induce a decrease in the battery capacity while exhibiting an appropriate level of adhesiveness. Preferably, the content of the binder can be 1 wt% - 10 wt% or 1 wt% - 5 wt% based on the total weight of the positive electrode material.

[0142] As the current collector, any material applicable to the positive electrode of a lithium secondary battery in the technical field to which the present invention pertains can be used without particular limitation.

[0143] As a non-limiting example, as the current collector, stainless steel; aluminum; nickel; titanium; fired carbon; or those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel can be used

[0144] can be used Preferably, the current collector has a thickness of 3 μm - 500 μm. In order to enhance the adhesive force of the positive electrode material, the current collector may have fine irregularities formed on its surface. The current collector can have various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0145] The positive electrode for the lithium secondary battery is formed by laminating a positive electrode material including the positive electrode active material, the conductive material, the sacrificial anode material, and a binder on the current collector.

[0146] V. Lithium Secondary Battery According to another embodiment of the present invention, There is provided a lithium secondary battery including the positive electrode for the lithium secondary battery, a negative electrode, a separator, and an electrolyte.

[0147] The lithium secondary battery includes a positive electrode containing the lithium transition metal oxide or the additive for the positive electrode of the lithium secondary battery. Therefore, the lithium secondary battery can suppress gas generation at the positive electrode during charge and discharge, and exhibit improved safety and life characteristics. And the lithium secondary battery can exhibit a high discharge capacity, excellent output characteristics, and capacity retention rate.

[0148] Therefore, the lithium secondary battery is used as an energy supply source having improved performance and safety in the field of portable electronic devices such as mobile phones, notebook computers, tablet computers, mobile batteries, digital cameras, etc.; and in the field of means of transportation such as electric vehicles, electric bicycles, and personal mobility devices.

[0149] The lithium secondary battery includes an electrode assembly wound with a separator interposed between a positive electrode and a negative electrode, and a case in which the electrode assembly is incorporated. And the positive electrode, the negative electrode, and the separator are impregnated with an electrolyte.

[0150] The lithium secondary battery can have various forms such as a square shape, a cylindrical shape, and a pouch shape.

[0151] Matters regarding the positive electrode are replaced with the contents described in the item of "IV. Positive Electrode for Lithium Secondary Battery".

[0152] The negative electrode may include a negative electrode material including a negative electrode active material, a conductive material, and a binder; and a current collector that supports the negative electrode material.

[0153] Examples of the negative electrode active material include substances capable of reversibly intercalating and deintercalating lithium ions, lithium metal, alloys of lithium metal, substances dopable and dedopable with lithium, and transition metal oxides.

[0154] Examples of the substances capable of reversibly intercalating and deintercalating lithium ions include carbonaceous substances, such as crystalline carbon, amorphous carbon, or mixtures thereof. Specifically, the carbonaceous substances may be natural graphite, artificial graphite, kish graphite, pyrolytic carbon, mesophase pitches, mesophase pitch based carbon fiber, meso-carbon microbeads, petroleum or coal tar pitch derived cokes, soft carbon, and hard carbon.

[0155] The alloy of lithium metal may be an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, Sn, Bi, Ga, and Cd.

[0156] The substances capable of doping and undoping with lithium can be Si, Si-C composite, SiOx (0 < x < 2), Si-Q alloy (where Q is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof; provided that Si is excluded.), Sn, SnO2, Sn-R alloy (where R is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof; provided that Sn is excluded.), etc. And as the substances capable of doping and undoping with lithium, at least one of the above examples and SiO2 can be mixed and used. The Q and R can be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, etc.

[0157] And the transition metal oxide can be vanadium oxide, lithium vanadium oxide, lithium titanate, etc.

[0158] Preferably, the negative electrode contains one or more negative electrode active materials selected from the group consisting of carbonaceous materials and silicon compounds.

[0159] Here, the carbonaceous material is one or more substances selected from the group consisting of natural graphite, artificial graphite, kish graphite, pyrolytic carbon, mesophase pitch, mesophase pitch-based carbon fiber, carbon microspheres, petroleum or coal-based coke, softened carbon, and hardened carbon described above. And the silicon compound can be a compound containing Si described above, that is, Si, Si-C composite, SiOx (0 < x < 2), the Si-Q alloy, a mixture thereof, or a mixture of at least one of these and SiO2.

[0160] According to one embodiment, the negative electrode active material is contained in an amount of 85% to 98% by weight based on the total weight of the negative electrode material.

[0161] Specifically, the content of the negative electrode active material can be 85% by weight or more, or 87% by weight or more, or 90% by weight or more; and 98% by weight or less, or 97% by weight or less, or 95% by weight or less based on the total weight of the negative electrode material.

[0162] Preferably, the content of the negative electrode active material can be 85% to 97% by weight, or 87% to 97% by weight, or 87% to 95% by weight, or 90% to 95% by weight based on the total weight of the negative electrode material.

[0163] Regarding the conductive material, the binder, and the current collector contained in the negative electrode material, the content described in the item of "IV. Positive electrode for lithium secondary battery" is substituted.

[0164] The separator separates the positive electrode and the negative electrode and provides a migration path for lithium ions. As the separator, any material applicable to the separator of a lithium secondary battery in the technical field to which the present invention pertains can be used without particular limitation. The separator preferably has a low resistance to the ion migration of the electrolyte and excellent wettability to the electrolyte.

[0165] Specifically, the separator can be a porous polymer film made of a polyolefin-based polymer such as polyethylene, polypropylene, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-methacrylate copolymer. The separator can be a multilayer film in which two or more layers of the porous polymer film are laminated. The separator can be a non-woven fabric containing glass fibers, polyethylene terephthalate fibers, etc. And the separator can be coated with a ceramic component or a polymer substance to ensure heat resistance or mechanical strength.

[0166] On the one hand, as the electrolyte, any electrolyte applicable to lithium secondary batteries in the technical field to which the present invention pertains can be used without particular limitation. For example, the electrolyte can be an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc.

[0167] Specifically, the electrolyte may contain a non-aqueous organic solvent and a lithium salt.

[0168] As the non-aqueous organic solvent, any medium that can play a role in allowing the ions involved in the electrochemical reaction of the battery to move can be used without particular limitation. Specifically, the non-aqueous organic solvent may be an ester solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; an ether solvent such as dibutyl ether and tetrahydrofuran; a ketone solvent such as cyclohexanone; an aromatic hydrocarbon solvent such as benzene and fluorobenzene; a carbonate solvent such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); an alcohol solvent such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a linear, branched or cyclic hydrocarbon group having 2 to 20 carbon atoms and containing a double bond aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; and sulfolane, etc.

[0169] Among the above examples, it is preferable to use a carbonate solvent as the non-aqueous organic solvent.

[0170] In particular, considering the charge-discharge performance of the battery and the compatibility with the sacrificial anode material, as the non-aqueous organic solvent, a mixture of a cyclic carbonate having high ionic conductivity and high dielectric constant (for example, ethylene carbonate, propylene carbonate) and a low-viscosity linear carbonate (for example, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate) is preferably used. In this case, it is advantageous for the expression of the above-described performance to mix and use the cyclic carbonate and the linear carbonate at a volume ratio of 1:1 to 1:9.

[0171] Further, as the non-aqueous organic solvent, a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of 1:2 to 1:10; or a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) at a volume ratio of 1 to 3:1 to 9:1 is preferably used.

[0172] The lithium salt contained in the electrolyte dissolves in the non-aqueous organic solvent and acts as a source of lithium ions in the battery to enable the operation of a basic lithium secondary battery, and plays a role in promoting the movement of lithium ions between the positive electrode and the negative electrode.

[0173] Specifically, the lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiN(SO2F)2 (LiFSI, lithium bis(fluorosulfonyl)imide), LiCl, LiI, and LiB(C2O4)2, etc. Preferably, the lithium salt can be LiPF6, LiFSI, and mixtures thereof.

[0174] The lithium salt is contained in the electrolyte at a concentration of 0.1 M to 2.0 M. The lithium salt contained in the above concentration range can exhibit excellent electrolyte performance by imparting appropriate conductivity and viscosity to the electrolyte.

[0175] Optionally, the electrolyte contains additives for the purpose of improving the life characteristics of the battery, suppressing the reduction of the battery capacity, improving the discharge capacity of the battery, and the like.

[0176] For example, the additives may be haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, triamide hexaline, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, and the like. The additives are contained at 0.1% by weight to 5% by weight based on the total weight of the electrolyte.

Effects of the Invention

[0177] The lithium transition metal oxide according to the present invention can minimize the side reaction with the electrolyte and suppress the gas generation during charge and discharge of the lithium secondary battery by maintaining the lattice structure stabilized by the introduction of different elements. The positive electrode additive for a lithium secondary battery containing the lithium transition metal oxide can improve the safety and life characteristics of the lithium secondary battery.

Brief Description of the Drawings

[0178]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0179] Hereinafter, the actions and effects of the invention will be specifically described with reference to specific examples of the invention. However, this is presented as an exemplification for helping the understanding of the invention. It is not intended that the scope of the rights of the invention be limited in any sense by the following examples, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the invention and the scope of the technical idea.

[0180] Example 1 (1) Synthesis of Lithium Transition Metal Oxide Li2O, CoO, ZnO and MgO were solid-phase mixed in a molar ratio of Li:Co:Zn:Mg = 6:0.77:0.2:0.33 to prepare a raw material mixture.

[0181] The temperature of the raw material mixture was raised at a rate of 1.6 °C / min for 6 hours in an Ar atmosphere, and then calcined at 600 °C for 12 hours to obtain a lithium transition metal oxide of Li6Co 0.77 Zn 0.2 Mg 0.03 O4.

[0182] The lithium transition metal oxide was pulverized using a jaw crusher and then classified using a sieve shaker.

[0183] (2) Manufacture of Lithium Secondary Battery As a positive electrode additive, the lithium transition metal oxide (Li6Co 0.77 Zn 0.2 Mg 0.03O4), carbon black as the conductive material and polyvinylidene fluoride (PVdF) as the binder were mixed in a weight ratio of 95:3:2 in an organic solvent (N-methylpyrrolidone) to produce a positive electrode material slurry. The positive electrode material slurry was applied to one side of a current collector, which was an aluminum foil with a thickness of 15 μm, and rolled and dried to produce a positive electrode. On the other hand, no positive electrode active material was added to the positive electrode material in this experiment. When a positive electrode active material was added, it was presented in Example 6 below.

[0184] As the negative electrode active material, natural graphite, as the conductive material, carbon black, and as the binder, carboxymethyl cellulose (CMC) were mixed in a weight ratio of 95:3:2 in an organic solvent (N-methylpyrrolidone) to produce a negative electrode material slurry. The negative electrode material slurry was applied to one side of a current collector, which was a copper foil with a thickness of 15 μm, and rolled and dried to produce a negative electrode.

[0185] A non-aqueous organic solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 3:4:3 was prepared. A lithium salt of 0.7 M concentration of LiPF6 and 0.5 M concentration of LiFSI was dissolved in the non-aqueous organic solvent to produce an electrolyte.

[0186] An electrode assembly was manufactured with a porous polyethylene, which was a separator, between the positive electrode and the negative electrode, and the electrode assembly was placed inside a case. The electrolyte was injected into the case to manufacture a lithium secondary battery in the form of a pouch cell.

[0187] Example 2 A lithium transition metal oxide of Li6Co 0.77 Zn 0.2 Al 0.03 O4 and (2) a lithium secondary battery containing this as a positive electrode additive were manufactured in the same manner as in Example 1 except that Al2O3 was used instead of MgO.

[0188] Example 3 A lithium transition metal oxide of Li6Co0.77 Zn 0.2 Ti 0.03 A lithium transition metal oxide of O4, and (2) a lithium secondary battery containing this as a cathode additive was produced.

[0189] Example 4 (1) Li6Co in the same manner as in Example 1 except that ZrO2 was used instead of MgO. 0.77 Zn 0.2 Zr 0.03 A lithium transition metal oxide of O4, and (2) a lithium secondary battery containing this as a cathode additive was produced.

[0190] Example 5 (1) Li6Co in the same manner as in Example 1 except that Nb2O5 was used instead of MgO. 0.77 Zn 0.2 Nb 0.03 A lithium transition metal oxide of O4, and (2) a lithium secondary battery containing this as a cathode additive was produced.

[0191] Example 6 (1) Li6Co in the same manner as in Example 1 except that a raw material mixture obtained by solid-phase mixing Li2O, CoO, ZnO, and Al2O3 in a molar ratio of Li:Co:Zn:Al = 6:0.7:0.25:0.05 was used. 0.7 Zn 0.25 Al 0.05 A lithium transition metal oxide of O4, and (2) a lithium secondary battery containing this as a cathode additive was produced.

[0192] Example 7 (1) Li6Co in the same manner as in Example 6 except that MgO was used instead of Al2O3. 0.7 Zn 0.25 Mg 0.05 A lithium transition metal oxide of O4, and (2) a lithium secondary battery containing this as a cathode additive was produced.

[0193] Example 8 A raw material mixture obtained by solid-phase mixing Li2O, CoO, ZnO, and TiO2 in a molar ratio of Li:Co:Zn:Ti = 6:0.72:0.25:0.03 was used, and (1) Li6Co 0.72 Zn 0.25 Ti 0.03 O4, a lithium transition metal oxide, and (2) a lithium secondary battery containing this as a cathode additive were manufactured in the same manner as in Example 1 above.

[0194] Example 9 A raw material mixture obtained by solid-phase mixing Li2O, CoO, ZnO, and ZrO2 in a molar ratio of Li:Co:Zn:Zr = 6:0.65:0.3:0.05 was used, and (1) Li6Co 0.72 Zn 0.25 Zr 0.03 O4, a lithium transition metal oxide, and (2) a lithium secondary battery containing this as a cathode additive were manufactured in the same manner as in Example 8 above.

[0195] Example 10 A raw material mixture obtained by solid-phase mixing Li2O, CoO, ZnO, and Al2O3 in a molar ratio of Li:Co:Zn:Al = 6:0.65:0.3:0.05 was used, and (1) Li6Co 0.65 Zn 0.3 Al 0.05 O4, a lithium transition metal oxide, and (2) a lithium secondary battery containing this as a cathode additive were manufactured in the same manner as in Example 1 above.

[0196] Example 11 A raw material mixture obtained by solid-phase mixing Li2O, CoO, ZnO, and Al2O3 in a molar ratio of Li:Co:Zn:Al = 6:0.65:0.25:0.1 was used, and (1) Li6Co 0.65 Zn 0.25 Al 0.1 O4, a lithium transition metal oxide, and (2) a lithium secondary battery containing this as a cathode additive were manufactured in the same manner as in Example 1 above.

[0197] Example 12 A raw material mixture obtained by solid-phase mixing Li2O, CoO, ZnO, and Al2O3 in a molar ratio of Li:Co:Zn:Al = 6:0.6:0.3:0.1 was used, and (1) a lithium transition metal oxide of Li6Co 0.6 Zn 0.3 Al 0.1 O4 and (2) a lithium secondary battery containing this as a cathode additive were produced in the same manner as in Example 1 except for the above.

[0198] Example 13 A lithium secondary battery was produced in the same manner as in Example 6 except that, during the production of the cathode, a cathode active material was further added, and during the production of the anode, the composition of the anode active material was changed.

[0199] Specifically, as the cathode active material, an NCMA (Li[Ni, Co, Mn, Al]O2)-based compound, NTA-X12M, L&F), as the cathode additive, the lithium transition metal oxide (Li6Co 0.7 Zn 0.25 Al 0.05 O4), carbon black as the conductive material, and polyvinylidene fluoride (PVdF) as the binder were mixed in a weight ratio of 93.8:1.2:3:2 in an organic solvent (N-methylpyrrolidone) to produce a cathode material slurry. The cathode material slurry was applied to one side of a current collector, which is an aluminum foil with a thickness of 15 μm, and rolled and dried to produce a cathode.

[0200] As the anode active material, a mixture of natural graphite and SiO (weight ratio = 9:1), carbon black as the conductive material, and carboxymethyl cellulose (CMC) as the binder were mixed in a weight ratio of 95:3:2 in an organic solvent (N-methylpyrrolidone) to produce an anode material slurry. The anode material slurry was applied to one side of a current collector, which is a copper foil with a thickness of 15 μm, and rolled and dried to produce an anode.

[0201] An electrode assembly was produced with a porous polyethylene, which is a separator, between the cathode and the anode, and the electrode assembly was placed inside the case. The electrolyte was injected into the case to produce a pouch cell-type lithium secondary battery.

[0202] Comparative Example 1 (1) A lithium transition metal oxide of Li6CoO4 and (2) a lithium secondary battery containing this as a cathode additive were produced in the same manner as in Example 1, except that Li2O and CoO were mixed at a molar ratio of Li:Co = 6:1 without adding ZnO and MgO.

[0203] Comparative Example 2 (1) A lithium transition metal oxide of Li6Co 0.7 Zn 0.3 O4 and (2) a lithium secondary battery containing this as a cathode additive were produced in the same manner as in Example 1, except that Li2O, CoO and ZnO were mixed at a molar ratio of Li:Co:Zn = 6:0.7:0.3 without adding MgO.

[0204] Comparative Example 3 During the production of the cathode, a lithium secondary battery was produced in the same manner as in Example 13, except that Li6Co 0.7 Zn 0.25 Al 0.05 O4 was used instead of Li6CoO4 obtained in Comparative Example 1.

[0205] Comparative Example 4 During the production of the cathode, a lithium secondary battery was produced in the same manner as in Example 13, except that Li6Co 0.7 Zn 0.25 Al 0.05 O4 was used instead of Li6Co 0.7 Zn 0.3 O4 obtained in Comparative Example 2.

[0206] Comparative Example 5 During the production of the cathode, an NCMA (Li[Ni, Co, Mn, Al]O2) - based compound, NTA - X12M, L&F) as the cathode active material and the lithium transition metal oxide (Li6Co 0.7 Zn 0.25 Al 0.05A lithium secondary battery was manufactured in the same manner as in Example 13, except that DN20 (Li2NiO2, POSCO Chemical) was used instead of O4), carbon black was used as the conductive material, and polyvinylidene fluoride (PVdF) was used as the binder, and they were mixed at a weight ratio of 91.2:3.8:3:2.

[0207] Comparative Example 6 During the production of the positive electrode, a lithium secondary battery was manufactured in the same manner as in Example 13, except that the positive electrode additive was not added.

[0208] Test Example 1 For the lithium secondary batteries of Examples 1 to 12, Comparative Example 1 and Comparative Example 2, the cumulative gas generation amount due to the cumulative charge and discharge cycles was measured by the following method, and the gas generation amount based on the measured cumulative charge capacity is shown in Table 1, Figures 1 and 2. The cumulative gas generation amount due to the high-temperature storage time is shown in Table 2.

[0209] (1) Measurement of Formation (initial charge) capacity and charge and discharge capacity The lithium secondary battery in pouch cell form was charged at a constant current-constant voltage up to 4.25V at 0.1C and discharged at a constant current up to 2.5V at 45°C, and rested for 20 minutes between charge and discharge for cycling. Then, the formation capacity and charge and discharge capacity were measured.

[0210] (2) Measurement of cumulative gas generation amount due to charge and discharge After operating the lithium secondary battery under the charge and discharge conditions of (1), the pouch cell at the time point when the gas generation amount was to be measured was recovered in a discharged state for a while. Using a hydrometer (MATSUHAKU, TWD-150DM), the difference between the original weight of the pouch cell and the weight in water was measured, the change in volume in the pouch cell was calculated, and the gas generation amount per weight was calculated by dividing the change in volume by the weight of the electrode active material.

[0211] (3) Measurement of cumulative gas generation amount due to high-temperature storage The pouch cell - type lithium secondary battery was charged at a constant current - constant voltage up to 4.25 V at 0.1 C under a temperature condition of 45 °C, then recovered, and the formation capacity was measured. After that, it was stored in a chamber at 60 °C. The lithium secondary battery was taken out of the chamber at one - week intervals, and using a hydrometer (MATSUHAKU, TWD - 150DM), the difference between the original weight of the pouch cell and the weight in water was measured, the change in volume within the pouch cell was calculated, and the amount of gas generation per weight was calculated by dividing the change in volume by the weight of the electrode active material.

[0212] The cumulative gas generation amounts after formation (0 th charge - discharge), 1 st , 2 nd , 10 th , 30 th and 50 th cycles are shown in Table 1 below.

[0213]

Table 1

[0214] As shown in Table 1 and Figure 1 above, in Examples 1 to 5, the initial charge capacity was smaller than that in Comparative Example 1 and Comparative Example 2. However, the cumulative gas generation amounts after 50 th cycles were all within 1 mL / g for Examples 1 to 5, showing a remarkably excellent gas reduction effect. In particular, Example 1 had the largest initial charge capacity among the examples and also had a relatively small cumulative gas generation amount. In Example 2, although the initial charge capacity was somewhat low, it was confirmed that it had the lowest cumulative gas generation amount and an excellent gas reduction effect.

[0215] As shown in Table 1 and Figure 2 above, in the case of Ti and Zr, the additional gas reduction effect due to the addition of different elements was relatively small. Referring to Example 6, Example 10, Example 11, and Example 12, it was confirmed that the higher the molar content of Al, the more excellent the gas reduction effect.

[0216] The cumulative gas generation amounts after formation (0 thAfter charge and discharge), the cumulative gas generation amounts after storage at 60 °C for 1 week, 2 weeks, 3 weeks, and 4 weeks are shown.

[0217]

Table 2

[0218] As shown in Table 2 above, in Examples 1 to 5, it was confirmed that the cumulative gas generation amount during high-temperature storage at 60 °C was within 1 mL / g, and had a significantly excellent gas reduction effect compared to Comparative Example 1 and Comparative Example 2.

[0219] Referring to Examples 6 to 12, in the case of lithium transition metal oxides into which Al was introduced, it was confirmed that they showed an excellent effect in reducing gas during high-temperature storage.

[0220] Test Example 2 For the lithium secondary batteries of Example 13 and Comparative Examples 3 to 6 in which the positive electrode active material and the positive electrode additive were mixed and applied, the capacity retention (cycle retention) and the cumulative gas generation amount due to the cumulative charge and discharge cycles were measured by the following method, and the measured capacity retention and cumulative gas generation amount are shown in FIG. 3 and Table 3.

[0221] (1) Measurement of Formation (initial charge) capacity and charge and discharge capacity A lithium secondary battery in pouch cell form was charged at a constant current-constant voltage up to 4.25 V at 0.1 C and discharged at a constant current up to 2.5 V under a temperature condition of 45 °C, and after performing cycles with a 20-minute rest between charge and discharge, the formation capacity and 100 th The charge and discharge capacity up to the cycle was measured.

[0222] (2) Measurement of the cumulative gas generation amount due to cumulative charge and discharge After operating the lithium secondary battery under the charge-discharge conditions of (1) above, when attempting to measure the gas generation amount, the pouch cell at the time point was recovered in a discharged state for a while. Using a hydrometer (MATSUHAKU, TWD-150DM), the difference between the original weight of the pouch cell and the weight in water was measured, the change in volume inside the pouch cell was calculated, and the gas generation amount per weight was calculated by dividing the change in volume by the weight of the electrode active material.

[0223] (3) Measurement of cumulative gas generation amount by high-temperature storage The lithium secondary battery in pouch cell form was charged at a constant current-constant voltage up to 4.25 V at 0.1C under a temperature condition of 45°C, and then recovered to measure the formation capacity. After that, it was stored in a chamber at 60°C. The lithium secondary battery was taken out of the chamber at one-week intervals, and using a hydrometer (MATSUHAKU, TWD-150DM), the difference between the original weight of the pouch cell and the weight in water was measured, the change in volume inside the pouch cell was calculated, and the gas generation amount per weight was calculated by dividing the change in volume by the weight of the electrode active material.

[0224] The formation (0 th charge-discharge) capacity, and then 50 th and 100 th The cumulative gas generation amount after cumulative cycles and the discharge capacity retention rate after 100 th cycles are shown.

[0225]

Table 3

[0226] As shown in Table 3 and Figure 3 above, the discharge capacities of Example 13 and Comparative Examples 3 to 5 appeared to be much larger compared to Comparative Example 6 where no positive electrode additive (sacrificial anode material) was applied. This is considered to be because the sacrificial anode material compensates for the irreversible lithium consumed in the formation of the SEI layer at the negative electrode.

[0227] On the reverse side, in the case of Comparative Example 6, since there is no sacrificial anode material to compensate for irreversible lithium, lithium in the cathode material is consumed, resulting in a decrease in discharge capacity and showing a discharge capacity of 201.3 mAh / g.

[0228] 100 of Example 13 th The cumulative gas generation amount in the cycle is 0.07 mL / g, which is less than 0.24 mL / g of Comparative Example 3 and 0.16 mL / g of Comparative Example 4, and also less than 0.20 mL / g of Comparative Example 6 where no sacrificial anode material is applied. This is because in Example 13, when Zn of Comparative Example 4 was introduced into Li6Co 0.7 Zn 0.3 By further introducing Al into Zn - only - introduced Li6CoO4, CoO2 formed after the initial charge is more effectively stabilized than in the case of introducing only Zn, effectively preventing side reactions with the electrolyte, and is considered to be due to the suppression of additional gas generation thereby.

[0229] 50 of Comparative Example 5 th The cumulative gas generation amount in the cycle is the least at 0.02 mL / g, but 50 th From cycle 50 to 100 th The gas generation increase amount in the cycle from 50 to 100 cycles is 0.09 mL / g, and thereafter, the gas generation may increase continuously. This is the same in Comparative Example 3. On the contrary, in the case of Example 13, 50 th From cycle 50 to 100 th The gas generation increase amount from cycle 50 to 100 cycles is 0.02 mL / g, and it is considered that the gas generation is suppressed as the charge - discharge cycle continues.

[0230] In Example 13, Comparative Example 3, and Comparative Example 4 to which a Co - based sacrificial anode material was applied, 100 thThe capacity retention rate in the cycle appeared to be 88.2% or more. In Comparative Example 5 where an Ni-based sacrificial anode material was applied and Comparative Example 6 where no sacrificial anode material was applied, the capacity retention rates were 86.3% and 86.2% respectively, which were significantly lower than that of Example 13. Particularly, in the case of Example 13 where Al was further introduced, it was confirmed that the capacity retention rate was greatly improved to 91.7%. This is considered to be because, as can be seen from the above cumulative gas generation amount, by stabilizing the crystal phase after the initial charge by the additional introduction of Al, side reactions with the electrolyte are prevented.

[0231] From now on, when a Co-based sacrificial anode material, particularly the sacrificial anode material having the composition of Chemical Formula 1, is applied to a lithium secondary battery containing an actual cathode material, not only is the initial discharge capacity preserved and the gas generation amount in the battery suppressed, but also th it was confirmed that the capacity retention rate after 100 cycles was also excellent.

[0232] The following Table 4 shows the cumulative gas generation amounts after formation (0 th charging), storage at 72 °C for 1 week, 2 weeks, 3 weeks, and 4 weeks.

[0233]

Table 4

[0234] As shown in Table 4 above, in Example 13, the cumulative gas generation amount after 4 weeks was the least at 0.15 mL / g. This is considered to be because, similar to the result of the charge-discharge cycle, the foreign element introduced into Li6CoO4 effectively stabilizes the CoO2 formed after the initial charge, prevents side reactions with the electrolyte, and suppresses additional gas generation due to this.

[0235] Also, in the case of Example 13, less gas was generated than in Comparative Example 6 where no sacrificial anode material was applied. This may be due to experimental error, or it is expected that the cathode additive contained in the lithium secondary battery not only suppresses gas generation but also absorbs the generated gas.

[0236] As described above, the present invention has been explained by way of limited embodiments and drawings. However, the present invention is not limited thereby, and it goes without saying that various modifications and variations can be made by those with ordinary knowledge in the technical field to which the present invention pertains within the equivalent scope of the technical idea of the present invention and the scope of the claims described below.

Claims

1. A lithium transition metal oxide represented by the following Chemical Formula 1, 【Chemical Formula 1】 Li6Co1−x−yZnxMyO4 In the Chemical Formula 1, M is a Group 2 element, a Group 13 element, a Group 14 element, a Period 5 transition metal, or a Period 6 transition metal, x is from 0.1 to 0.7, y is from 0.01 to 0.2, the lithium transition metal oxide.

2. The lithium transition metal oxide according to Claim 1, wherein the M is at least one selected from the group consisting of Al, Mg, Ti, Zr, Nb, and W.

3. The lithium transition metal oxide is Li ６ Co ０．７７ Zn ０．２ Al ０．０３ O ４ 、Li ６ Co ０．７６ Zn ０．２ Al ０．０４ O ４ 、Li ６ Co ０．７５ Zn ０．２ Al ０．０５ O ４ 、Li ６ Co ０．７ Zn ０．２５ Al ０．０５ O ４ 、Li ６ Co ０．６５ Zn ０．２５ Al ０．１ O ４ 、Li ６ Co ０．６７ Zn ０．３ Al ０．０３ O ４ 、Li ６ Co ０．６６ Zn ０．３ Al ０．０４ O ４ 、Li ６ Co ０．６５ Zn ０．３ Al ０．０５ O ４ 、Li ６ Co ０．６ Zn ０．３ Al ０．１ O ４ 、Li ６ Co ０．７７ Zn ０．２ Mg ０．０３ O ４ 、Li ６ Co ０．７６ Zn ０．２ Mg ０．０４ O ４ 、Li ６ Co ０．７５ Zn ０．２ Mg ０．０５ O ４ 、Li ６ Co ０．７ Zn ０．２５ Mg ０．０５ O ４ 、Li ６ Co ０．６７ Zn ０．３ Mg ０．０３ O ４ 、Li ６ Co ０．６６ Zn ０．３ Mg ０．０４ O ４ 、Li ６ Co ０．６５ Zn ０．３ Mg ０．０５ O ４ 、Li ６ Co ０．７７ Zn ０．２ Ti ０．０３ O ４ 、Li ６ Co ０．７６ Zn ０．２ Ti ０．０４ O ４ 、Li ６ Co ０．７５ Zn ０．２ Ti ０．０５ O ４ 、Li ６ Co ０．７２ Zn ０．２５ Ti ０．０３ O ４ 、Li ６ Co ０．６７ Zn ０．３ Ti ０．０３ O ４ 、Li ６ Co ０．６６ Zn ０．３ Ti ０．０４ O ４ 、Li ６ Co ０．６５ Zn ０．３ Ti ０．０５ O ４ 、Li ６ Co ０．７７ Zn ０．２ Zr ０．０３ O ４ 、Li ６ Co ０．７６ Zn ０．２ Zr ０．０４ O ４ 、Li ６ Co ０．７５ Zn ０．２ Zr ０．０５ O ４ 、Li ６ Co ０．７２ Zn ０．２５ Zr ０．０３ O ４ , Li ６ Co ０．６７ Zn ０．３ Zr ０．０３ O ４ , Li ６ Co ０．６６ Zn ０．３ Zr ０．０４ O ４ , Li ６ Co ０．６５ Zn ０．３ Zr ０．０５ O ４ , Li ６ Co ０．７７ Zn ０．２ Nb ０．０３ O ４ , Li ６ Co ０．７６ Zn ０．２ Nb ０．０４ O ４ , Li ６ Co ０．７５ Zn ０．２ Nb ０．０５ O ４ , Li ６ Co ０．６７ Zn ０．３ Nb ０．０３ O ４ , Li ６ Co ０．６６ Zn ０．３ Nb ０．０４ O ４ , Li ６ Co ０．６５ Zn ０．３ Nb ０．０５ O ４ , Li ６ Co ０．７７ Zn ０．２ W ０．０３ O ４ , Li ６ Co ０．７６ Zn ０．２ W ０．０４ O ４ , Li ６ Co ０．７５ Zn ０．２ W ０．０５ O ４ , Li ６ Co ０．６７ Zn ０．３ W ０．０３ O ４ 、 Li ６ Co ０．６６ Zn ０．３ W ０．０４ O ４ 、 and Li ６ Co ０．６５ Zn ０．３ W ０．０５ O ４ The lithium transition metal oxide according to claim 1, comprising one or more compounds selected from the group consisting of

4. A first step of solid-phase mixing a lithium oxide, a cobalt oxide, and a heterogeneous element oxide; A second step of firing the mixture obtained in the first step in an inert atmosphere at a temperature of 550°C to 750°C to obtain the lithium transition metal oxide according to any one of Claims 1 to 3, a method for producing a lithium transition metal oxide.

5. The method for producing a lithium transition metal oxide according to Claim 4, wherein in the second step, the mixture obtained in the first step is heated in an inert atmosphere at a heating rate of 1.4°C / min to 2.0°C / min and fired at a temperature of 550°C to 750°C for 2 hours to 20 hours.

6. A positive electrode additive for a lithium secondary battery, comprising the lithium transition metal oxide according to any one of Claims 1 to 3.

7. A positive electrode for a lithium secondary battery, comprising a positive electrode active material, a binder, a conductive material, and the lithium transition metal oxide according to any one of Claims 1 to 3.

8. A positive electrode for a lithium secondary battery, comprising a positive electrode active material, a binder, a conductive material, and the positive electrode additive for a lithium secondary battery according to Claim 6.

9. A lithium secondary battery, comprising the positive electrode for a lithium secondary battery according to Claim 7 or 8, a negative electrode, a separator, and an electrolyte.

10. The lithium secondary battery according to Claim 9, wherein the negative electrode contains at least one negative electrode active material selected from the group consisting of a carbonaceous material and a silicon compound.

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