Secondary battery comprising gas scavenging member

Abstract

The present invention provides a secondary battery in which an electrode assembly is sealed inside a pouch-type battery case together with an electrolyte, wherein a gas collecting member is disposed on at least one surface of the inner surface of the battery case, and the gas collecting member is in the form of containing a mixed solution of an ionic liquid and an amine-based compound inside the pouch.

Description

Technology Field

[0001] The present invention relates to a secondary battery comprising a gas-collecting member. Background Technology

[0002] Due to the rapid increase in the use of fossil fuels, there is a growing demand for alternative or clean energy, and as part of this, the fields of power generation and energy storage utilizing electrochemistry are the most actively researched.

[0003] Currently, a representative example of an electrochemical device utilizing such electrochemical energy is the secondary battery, and its scope of application is steadily expanding.

[0004] Recently, as technology development and demand for portable devices such as portable computers, mobile phones, and cameras have increased, the demand for secondary batteries as an energy source has been rapidly increasing. Among such secondary batteries, much research has been conducted on environmentally friendly lithium secondary batteries that exhibit high charge / discharge characteristics and lifespan characteristics, and they have also been commercialized and are widely used.

[0005] Generally, a lithium secondary battery is structured such that a non-aqueous electrolyte is impregnated into an electrode assembly composed of a positive electrode, a negative electrode, and a porous separator. Additionally, generally, the positive electrode is manufactured by coating a positive electrode composite containing a positive electrode active material onto aluminum foil, and the negative electrode is manufactured by coating a negative electrode composite containing a negative electrode active material onto copper foil.

[0006] In addition, pouch-type batteries with a structure in which a stacked or stacked / folded electrode assembly is embedded in a pouch-type battery case made of aluminum laminate sheets are attracting a lot of attention due to reasons such as low manufacturing costs, small weight, and easy shape deformation, and their usage is gradually increasing.

[0007] Meanwhile, as the demand for secondary batteries gradually expands, there is a growing requirement for high energy, high output, and long-term safety. Accordingly, the use of cathode materials with high Ni content, which exhibit high energy and high output, is increasing.

[0008] However, when using the aforementioned high-Ni content cathode material, swelling due to gas generation, performance degradation, and packing venting issues occur in pouch-type secondary batteries due to CO2 generation at high temperatures.

[0009] Therefore, it is necessary to develop secondary batteries that can solve these problems. The problem to be solved

[0010] The problem that the present invention aims to solve is to provide a secondary battery that can improve lifespan characteristics and ensure safety by effectively capturing gas generated during the operation of the secondary battery through the inclusion of a gas-capturing member. means of solving the problem

[0011] According to one embodiment of the present invention for achieving these objectives,

[0012] As a secondary battery in which an electrode assembly is sealed inside a pouch-type battery case together with an electrolyte,

[0013] A gas collecting member is disposed on at least one surface of the inner surface of the battery case, and

[0014] The above gas-collecting member provides a secondary battery in which a mixed solution of an ionic liquid and an amine-based compound is contained inside a pouch.

[0015] In one specific example, the pouch may be made of a gas-permeable polymer, and the gas-permeable polymer may be a Poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene]-based material.

[0016] More specifically, the gas-permeable polymer may be Teflon AF 2400.

[0017] In one specific example, the amine-based compound may be an alkanolamine.

[0018] In addition, the mixed solution of the above amine-based compound and ionic liquid may be included in an amount of 50 ml to 200 ml.

[0019] At this time, the amine-based compound may be included in an amount of 5% to 30% by weight based on the total weight of the mixed solution.

[0020] The above ionic liquid is bis(trifluoromethane)sulfoneimide (Tf2N) as an anion. - ), [CF3SO2] - , [CF3CO2] - [PF6] - As a cation, it may be a combination of one or more selected from the group consisting of 1-butyl-3-methylimidazolium (bmim), 1-butyl-1-methylpyrrolidinium (bmpyr), and butyltrimethylammonium (btmamm).

[0021] Meanwhile, in one specific example, the gas collecting member is a pouch structure, and a mixed solution injection port is formed on one side of the gas collecting member, and the mixed solution injection port may be sealed when the mixed solution is injected.

[0022] Such gas-collecting members can be placed on the upper inner surface of the battery case based on the stacking direction of the electrode assembly.

[0023] In addition, the gas-collecting member may be formed with a size smaller than the area of ​​the top of the electrode assembly based on the stacking direction of the electrode assembly.

[0024] Meanwhile, in one specific example, the electrode assembly comprises an anode, a cathode, and a separator interposed between the anode and the cathode, and

[0025] The above positive electrode has a positive electrode composite containing a positive electrode active material formed on at least one surface of a positive electrode current collector, and

[0026] The above positive active material may include a lithium nickel-based transition metal oxide containing 80 mol% or more of Ni among the total molar of transition metals excluding lithium.

[0027] Specifically, the lithium nickel-based transition metal oxide can be represented by the following chemical formula 1.

[0028] Li 1+x Ni a Co b M c O2(2)

[0029] Here, 0≤x≤0.5, 0.8≤a≤1, 0≤b≤0.2, 0≤c≤0.2, and M is one or more selected from the group consisting of Mn, Al, Ti, Mg, Zr, W, Y, Sr, F, Si, Na, Cu, Fe, Ca, S and B.

[0030] More specifically, the lithium nickel-based transition metal oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi a Co b (Mn y A z ) c O2, LiNi a Co b A c O2, where a, b, and c are as defined above, and A may be one or more selected from the group consisting of Al, Ti, Mg, Zr, W, Y, Sr, F, Si, Na, Cu, Fe, Ca, S, and B. Effects of the invention

[0031] As described above, a secondary battery according to one embodiment of the present invention includes a gas-collecting member comprising a mixed solution of an ionic liquid and an amine-based compound, thereby effectively collecting gas generated during the operation of the secondary battery to improve lifespan characteristics, prevent issues such as packaging venting, and ensure safety. Brief explanation of the drawing

[0032] FIG. 1 is a schematic diagram of a secondary battery according to one embodiment of the present invention; FIG. 2 is a schematic diagram of the process for manufacturing a gas collection member included in the secondary battery of FIG. 1; FIG. 3 is a schematic diagram of the process of manufacturing a gas collection member according to another embodiment of the present invention. Specific details for implementing the invention

[0033] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0034] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall 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.

[0035] The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0036] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0038] A secondary battery according to one embodiment of the present invention may be in the form in which an electrode assembly is sealed together with an electrolyte inside a pouch-type battery case. According to the present embodiment, a gas collecting member is disposed on at least one surface of the inner surface of the battery case, and the gas collecting member may be in the form of a mixed solution contained inside a pouch. In this case, the pouch may be made of a gas-permeable polymer, and the mixed solution may be a mixture of an ionic liquid and an amine-based compound.

[0039] Here, the gas-permeable polymer may, in detail, be a Poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene]-based material, and more specifically, may be Teflon AF 2400.

[0040] In addition, the amine-based compound contained inside the pouch made of the above gas-permeable polymer may, in detail, be an alkanolamine, and more specifically, be one or more selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, methyl diethanolamine, and 2-amino 2-methyl 1-propanol.

[0041] As another component, the ionic liquid is bis(trifluoromethane)sulfoneimide (Tf2N) as an anion. - ), [CF3SO2] - , [CF3CO2] - [PF6] -and as a cation, it may be a combination of one or more selected from the group consisting of 1-butyl-3-methylimidazolium (bmim), 1-butyl-1-methylpyrrolidinium (bmpyr), and butyltrimethylammonium (btmamm).

[0042] At this time, the mixed solution containing an amine-based compound and an ionic liquid included in the gas-collecting member may be included in an amount of 50% to 95% of the total volume inside the pouch, for example, depending on the size of the pouch, and in detail, in an amount of 60% to 80%.

[0043] In addition, of course, the size of the pouch may vary depending on the size of the secondary battery, and thus the absolute amount of the mixed solution may vary accordingly. However, since sufficient gas collection is possible when at least 50 ml is included, it is desirable to include at least 50 ml of the mixed solution. On the other hand, if too much is included, the volume occupied by the gas collection member in the secondary battery becomes too large, so specifically, it is desirable to include 200 ml or less.

[0044] In addition, the amine-based compound included in the above mixed solution may be included in an amount of 5% to 30% by weight based on the total weight of the mixed solution, more specifically, in an amount of 10% to 20% by weight, and more specifically, in an amount of 10% to 15% by weight.

[0045] If included in an amount that is too small, outside the above range, the amine compound is insufficient and the gas capture effect is reduced, and if included in an amount that is too large, the carbon dioxide absorption products, such as bicarbonate and free amine, may precipitate in the ionic liquid, which is undesirable.

[0046] Meanwhile, the gas collecting member may be disposed on at least one surface of the inner surface of the battery case, specifically on the upper inner surface of the battery case with respect to the electrode assembly stacking direction.

[0047] At this time, the phrase "placed on the inner surface of the battery case" means that the gas collecting member may be attached to the inner surface of the battery case, may be attached to the electrode assembly subsequently installed therein, or may be formed without being attached as a separate member. However, it is preferable that the gas collecting member be attached to the inner surface of the battery case or to the electrode assembly so that the pouch can be fixed on the inner surface of the battery case, and more specifically, it may be attached to the inner surface of the battery case so as not to interfere with the electrolyte impregnation of the electrode assembly.

[0048] In addition, as described above, the gas collecting member may be formed with a size smaller than the upper surface area of ​​the electrode assembly based on the stacking direction of the electrode assembly, and specifically, may be 0.2% to 15% smaller than the upper surface area of ​​the electrode assembly.

[0049] If the gas collecting member is formed too small outside the above range, it is undesirable because it cannot sufficiently collect the gas generated during the operation of the secondary battery.

[0050] As an example, a schematic diagram of a secondary battery according to one embodiment of the present invention is shown in Fig. 1 below.

[0051] Referring to FIG. 1, the secondary battery (100) is structured such that an electrode assembly (110) is sealed inside a pouch-type battery case (130) together with an electrolyte (120), and a gas collecting member (140) is disposed between the upper surface of the electrode assembly (110) and the upper inner surface of the battery case (130), that is, between the upper surface of the electrode assembly (110) and the upper surface of the battery case (130).

[0052] At this time, the gas collecting member (140) may be attached to the upper surface of the electrode assembly (100), or attached to the upper inner surface of the battery case (130), or simply interposed between the upper surface of the electrode assembly (100) and the upper inner surface of the battery case (130) as a separate member.

[0053] At this time, the size of the manufactured gas collecting member (140) can be designed to be smaller than the width and length of the upper surface of the electrode assembly (100).

[0054] Here, the gas collecting member (140) can be manufactured in a manner such as the shape shown in FIG. 2 and FIG. 3, for example.

[0055] Referring first to FIG. 2, a film made of two gas-permeable polymers can be manufactured by high-temperature sealing three sides to form a pouch shape, including three sealing portions (141) and one mixing solution injection port (142), then injecting a mixing solution according to the present invention through the mixing solution injection port (142) (process (b)), and then high-temperature sealing the mixing solution injection port (142) (process (c)).

[0056] Alternatively, referring to FIG. 3, a film made of a gas-permeable polymer can be manufactured by folding a film made of one sheet of gas permeable polymer in half to include two sealing portions (141') and one mixing solution injection port (142'), high-temperature sealing two sides of the folded portion (process (a)), injecting a mixing solution according to the present invention through the mixing solution injection port (142) (process (b)), and then high-temperature sealing the mixing solution injection port (142) (process (c)).

[0057] Accordingly, the gas collecting member according to the present invention has a pouch structure, wherein a mixed solution injection port is formed on one side of the gas collecting member, and the mixed solution injection port may be in a sealed form when the mixed solution is injected.

[0058] Meanwhile, the electrode assembly comprises a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode has a positive electrode composite containing a positive electrode active material formed on at least one surface of a positive electrode current collector, and the positive electrode active material may include a lithium nickel-based transition metal oxide containing 80 mol% or more of Ni among the total molar of transition metals excluding lithium.

[0059] Here, the lithium nickel-based transition metal oxide can be represented by the following chemical formula 1.

[0060] Li 1+x Ni a Co b M c O2(2)

[0061] Here, 0≤x≤0.5, 0.8≤a≤1, 0≤b≤0.2, 0≤c≤0.2, and M is one or more selected from the group consisting of Mn, Al, Ti, Mg, Zr, W, Y, Sr, F, Si, Na, Cu, Fe, Ca, S and B.

[0062] More specifically, lithium nickel-based transition metal oxides are LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi a Co b (Mn y A z ) c O2, LiNi a Co b A c O2, where a, b, and c are as defined above, and A may be one or more selected from the group consisting of Al, Ti, Mg, Zr, W, Y, Sr, F, Si, Na, Cu, Fe, Ca, S, and B.

[0063] When the above lithium nickel-based transition metal oxide, that is, an oxide in which the nickel content is 80 mol% or more of the total moles of transition metals excluding lithium, is included as a positive electrode active material, it is suitable for requirements such as high energy and high output, but the rate of performance degradation due to gas traps and venting issues is high, such as the generation of a large amount of CO2 at high temperatures. Accordingly, since the requirement for gas control is higher, a secondary battery including a gas capture member according to the present invention can operate efficiently.

[0064] Meanwhile, the above-mentioned positive active material is, for example, of the chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; chemical formula LiMn 2-x M x A lithium manganese composite oxide represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of the Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc. may be further included, and if the composition of the cathode active material is a conventionally known composition, it is not limited to only these and may include additional materials.

[0065] The above-mentioned anode composite may further include a conductive material and a binder along with the anode active material described above.

[0066] The above-mentioned cathode may be manufactured in a form in which a cathode composite containing a cathode active material is coated on a cathode current collector, and the cathode composite may further include a conductive material and a binder as described above, together with the cathode active material.

[0067] Since the above-mentioned positive current collector, negative active material, negative current collector, conductive material, binder, etc., are well known in the art, a detailed description is omitted in this specification.

[0068] In addition, the separator included in the electrode assembly of the secondary battery, the electrolyte embedded together with the electrode assembly in the secondary battery, and the laminate sheet configuration of the battery case are as known in the art, so a detailed description is omitted in this specification.

[0070] Hereinafter, preferred embodiments of the present invention, comparative examples, and experimental examples for evaluating them are described. However, the above embodiments are merely illustrative of this description, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of this description, and that such variations and modifications fall within the scope of the appended claims.

[0072] <Preparation Example 1>

[0073] Manufacture of gas capture components

[0074] Two sheets of Teflon AF 2400 film were prepared, and three sides of them were sealed to prepare a pouch equipped with an injection port.

[0075] A mixed solution was prepared by dissolving monoethanolamine (MEA) as an amine compound in bis(trifluoromethane)sulfoneimide (Tf2N) as an ionic liquid, at a concentration of 10% by weight based on the total weight of the mixed solution.

[0076] 50 ml of the above mixed solution was injected into the above pouch, and the injection port was sealed to prepare gas collection member 1.

[0078] <Preparation Example 2>

[0079] Manufacture of gas capture components

[0080] A gas-collecting member 2 was prepared by manufacturing in the same manner as in Manufacturing Example 1 above, except that diethanolamine (DEA) was used as the amine-based compound.

[0082] <Preparation Example 3>

[0083] Manufacture of gas capture components

[0084] A gas-collecting member 3 was prepared in the same manner as in Preparation Example 1 above, except that monoethanolamine was dissolved as an amine-based compound in an amount of 30% by weight based on the total weight of the mixed solution.

[0086] <Preparation Example 4>

[0087] Manufacture of gas capture components

[0088] A gas-collecting member 4 was prepared in the same manner as in Preparation Example 1 above, except that monoethanolamine was dissolved as an amine-based compound in an amount of 5% by weight based on the total weight of the mixed solution.

[0090] <Preparation Example 5>

[0091] Manufacture of gas capture components

[0092] A gas-collecting member 5 was prepared by manufacturing in the same manner as in Manufacturing Example 1 above, except that only 30 ml of the mixed solution was injected into a pouch.

[0094] <Preparation Example 6>

[0095] Manufacture of gas capture components

[0096] A gas-collecting member 6 was prepared in the same manner as in Preparation Example 1 above, except that instead of the mixed solution in the pouch, 50 ml of a liquid electrolyte in which LiPF6 is dissolved at 1 M in a solvent mixed with ethylene carbonate and ethyl methyl carbonate in a 3:7 (volume ratio) was injected.

[0098] <Example 1>

[0099] LiNi as the positive active material 0.8 Co 0.1 Mn0.1 O2 was used, and a cathode active material slurry was prepared by adding 96 wt% of cathode active material, 2.0 wt% of Super-P (conductive material), and 2.0 wt% of PVdF (binder) to NMP (N-methyl-2-pyrrolidone), which is a solvent.

[0100] The above anode mixture slurry was coated onto an aluminum foil to a thickness of 50 μm, and an anode was manufactured by drying and rolling in a dryer at 130 degrees Celsius at a speed of 0.2 m / min (about 5 minutes) for NMP drying.

[0101] Artificial graphite was used as the cathode active material, and a cathode active material slurry was prepared by adding 96.3 wt% of artificial graphite, 1.0 wt% of Super-P (conductive agent), and 2.7 wt% of PVdF (binder) to NMP, which is a solvent, then coating it to a thickness of 70 μm on a copper foil, drying it in a dryer at 130 degrees Celsius at a speed of 0.2 m / min (about 5 minutes), and rolling it to produce a cathode.

[0102] An electrode assembly was manufactured using the anode and cathode prepared above, and a polyethylene film (Celgard, thickness: 20 μm) as a separator.

[0103] A gas collecting member 1 of Manufacturing Example 1 was placed on top of the electrode assembly, and after placing it in a battery case, a secondary battery was manufactured by injecting and sealing a liquid electrolyte in which LiPF6 is dissolved at 1M in a solvent mixed with ethylene carbonate, dimethylene carbonate, and diethyl carbonate in a volume ratio of 1:2:1.

[0105] <Example 2>

[0106] A secondary battery was manufactured in the same manner as in Example 1 above, except that gas collecting member 2 was used instead of gas collecting member 1 as the gas collecting member.

[0108] <Example 3>

[0109] A secondary battery was manufactured in the same manner as in Example 1 above, except that gas collecting member 3 was used instead of gas collecting member 1 as the gas collecting member.

[0111] <Example 4>

[0112] A secondary battery was manufactured in the same manner as in Example 1 above, except that gas collecting member 4 was used instead of gas collecting member 1 as the gas collecting member.

[0114] <Example 5>

[0115] A secondary battery was manufactured in the same manner as in Example 1 above, except that gas collecting member 5 was used instead of gas collecting member 1 as the gas collecting member.

[0117] <Comparative Example 1>

[0118] A secondary battery was manufactured in the same manner as in Example 1 above, except that a gas collection member was not used.

[0120] <Comparative Example 2>

[0121] A secondary battery was manufactured in the same manner as in Example 1 above, except that a gas collecting member 6 was placed instead of a gas collecting member 1.

[0123] <Experimental Example 1>

[0124] The secondary batteries prepared in Examples 5 to Comparative Example 2 above were charged to 4.2V at 0.1C and 5mA and stored in a convection oven at 60℃ for 2 weeks, after which the amount of gas generated in the secondary batteries was measured by GC-Mass analysis, and the results are shown in Table 1 below.

[0125] Gas generation amount (CO2 content, µl) Example 1 267 Example 2 375 Example 3 106 Example 4 1032 Example 5 633 Comparative Example 1 1619 Comparative Example 2 1465

[0126] Referring to Table 1, it can be seen that when a gas-collecting member comprising an ionic liquid and an amine-based compound is manufactured and formed as in the present invention, the amount of gas generated is significantly reduced compared to cases where it is not formed or a general electrolyte composition is added.

[0128] <Experimental Example 2>

[0129] After charging to 4.2V at 0.5C, charging to a constant voltage of 0.05C, and discharging to 2.5V at 0.5C, this was repeated for 800 cycles at a temperature of 45℃. Afterward, the discharge capacity retention rate (discharge capacity @ 800 cycles / initial capacity x 100) was calculated and the venting status was checked, and the results are shown in Table 2 below.

[0130] Capacity retention rate (%) Pouch venting status Example 1 82.2 No Example 2 81.9 No Example 3 82.1 No Example 4 78.6 No Example 5 81.7 No Comparative Example 1 68.5 Yes Comparative Example 2 72.3 Yes

[0131] Referring to Table 2, it can be seen that in the case according to the present invention, no venting occurs and the capacity retention rate is significantly improved.

[0132] A person skilled in the art to which this invention pertains will be able to make various applications and modifications within the scope of this invention based on the above content.

Claims

Claim 1 A secondary battery in which an electrode assembly is sealed inside a pouch-type battery case together with an electrolyte, wherein a gas collecting member is disposed on at least one surface of the inner surface of the battery case, and wherein the gas collecting member contains a mixed solution of an ionic liquid and an amine-based compound inside a pouch made of a gas-permeable polymer. Claim 2 delete Claim 3 In claim 1, the gas-permeable polymer is a secondary battery in which the material is a Poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene]-based material. Claim 4 In claim 1, the gas-permeable polymer is a secondary battery in which Teflon AF 2400. Claim 5 A secondary battery according to claim 1, wherein the amine-based compound is an alkanolamine. Claim 6 A secondary battery according to claim 1, wherein the mixed solution is contained in an amount of 50 ml to 200 ml. Claim 7 A secondary battery according to claim 1, wherein the amine-based compound is contained in an amount of 5% to 30% by weight based on the total weight of the mixed solution. Claim 8 In claim 1, the ionic liquid is bis(trifluoromethane)sulfoneimide (Tf2N) as an anion - ), [CF3SO2] - , [CF3CO2] - [PF6] - A secondary battery comprising a combination of one or more selected from the group consisting of 1-butyl-3-methylimidazolium (bmim), 1-butyl-1-methylpyrrolidinium (bmpyr), and butyltrimethylammonium (btmamm) as cations. Claim 9 A secondary battery according to claim 1, wherein the gas collecting member is a pouch structure, a mixed solution injection port is formed on one side of the gas collecting member, and the mixed solution injection port is sealed when the mixed solution is injected. Claim 10 In claim 1, the gas collecting member is a secondary battery disposed on the upper inner surface of the battery case with respect to the stacking direction of the electrode assembly. Claim 11 In claim 1, the gas-collecting member is formed with a size smaller than the area of ​​the top of the electrode assembly based on the stacking direction of the electrode assembly, in a secondary battery. Claim 12 A secondary battery according to claim 1, wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode has a positive electrode composite comprising a positive electrode active material formed on at least one surface of a positive electrode current collector, and the positive electrode active material comprises a lithium nickel-based transition metal oxide containing 80 mol% or more of Ni among the total molar of transition metals excluding lithium. Claim 13 In claim 12, the lithium nickel-based transition metal oxide is a secondary battery:Li represented by the following chemical formula 1. 1+x Ni a Co b M c O2(2) Here, 0≤x≤0.5, 0.8≤a≤1, 0≤b≤0.2, 0≤c≤0.2, and M is one or more selected from the group consisting of Mn, Al, Ti, Mg, Zr, W, Y, Sr, F, Si, Na, Cu, Fe, Ca, S and B. Claim 14 In Clause 13, the lithium nickel-based transition metal oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi a Co b (Mn y A z ) c O2, LiNi a Co b A c A secondary battery in which O2, wherein a, b, and c are as defined above, and A is one or more selected from the group consisting of Al, Ti, Mg, Zr, W, Y, Sr, F, Si, Na, Cu, Fe, Ca, S, and B.

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