Lithium secondary battery

Abstract

Provided is a secondary battery comprising: an electrode stack including a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode; a battery case surrounding the electrode stack; an electrode lead electrically connected to the positive electrode or the negative electrode and extending to the outside of the battery case; and an O2 sensor layer provided inside the battery case, wherein the O2 sensor layer contains a material that changes in electrical properties upon reacting with O2.

Description

lithium secondary battery

[0001] The present invention relates to a lithium secondary battery, and more specifically, to a lithium secondary battery capable of estimating the internal oxygen concentration more accurately and conveniently.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0182833 dated December 10, 2024, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0003] Lithium-replenishing compounds can be used in the cathode to manufacture high-energy and long-life secondary batteries. Lithium-replenishing compounds that are not completely consumed during the activation process can have adverse effects on cell performance and safety, such as Li precipitation or the release of large amounts of gas, during the actual use of the secondary battery. Therefore, there is a need for a means to detect whether there is excessive gas generation caused by residual lithium-replenishing compounds.

[0004] The technical problem that the present invention aims to solve is to provide a lithium secondary battery capable of estimating the internal oxygen concentration more accurately and conveniently.

[0005] To achieve the above technical objective, the present invention provides a lithium secondary battery comprising: an electrode stack including a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode; a battery case surrounding the electrode stack; an electrode lead electrically connected to the positive electrode or the negative electrode and extending to the outside of the battery case; and an O2 sensor layer provided inside the battery case, wherein the O2 sensor layer comprises a material that changes its electrical properties upon reaction with O2.

[0006] In some embodiments, the O2 sensor layer may include zirconia (ZrO2).

[0007] In some embodiments, the battery case is a pouch case, and the O2 sensor layer may be provided between the sealing portion of the pouch case and the electrode laminate.

[0008] In some embodiments, the O2 sensor layer may be provided on the inner surface of the pouch case.

[0009] In some embodiments, the O2 sensor layer may be configured to extend from the inner surface of the pouch case and be electrically connected to the electrode lead.

[0010] In some embodiments, the O2 sensor layer may be configured to be in physical contact with the electrode lead.

[0011] In some embodiments, one end of the O2 sensor layer is physically in contact with the electrode lead, and the other end of the O2 sensor layer may be exposed to the outside through the sealing portion.

[0012] In some embodiments, the O2 sensor layer may be provided between the electrode lead and the sealing portion.

[0013] In some embodiments, the anode comprises an anode current collector and an anode active material layer disposed on the anode current collector, and the anode active material layer may comprise LiFeO2.

[0014] In some embodiments, the positive active material layer may further include a sacrificial positive material which is a compound of Formula 1.

[0015] <Chemical Formula 1>

[0016] Li a Fe 1-x M x O y

[0017] (Here, 1 <a≤5, 0≤x≤0.35, 2<y≤4, M은 Ga, Zr, Ti, Mg, Ca, Ba, Sc, Mn, Zn, Cu, V, Cr, Sr, In, Al, 또는 그 조합임)

[0018] In some embodiments, the content of LiFeO2 in the positive active material layer may be 0.1% to 5% by weight based on the total weight of the positive active material layer.

[0019] Another aspect of the present invention provides a lithium secondary battery comprising: a positive electrode including a positive current collector and a positive active material layer disposed on the positive current collector and comprising LiFeO2; a negative electrode including a negative current collector and a negative active material layer disposed on the negative current collector; a battery case surrounding the positive electrode and the negative electrode; and an O2 sensor layer provided inside the battery case and comprising zirconia (ZrO2), wherein the ZrO2 of the O2 sensor layer has a tetragonal crystal structure.

[0020] In some embodiments, the O2 sensor layer may contain about 3 wt% to about 8 wt% of a dopant.

[0021] In some embodiments, the dopant of the O2 sensor layer may include one or more selected from the group consisting of calcium, magnesium, and yttria.

[0022] In some embodiments, the lithium secondary battery further comprises an electrode lead that is electrically connected to the positive electrode or the negative electrode and extends to the outside of the battery case, and the O2 sensor layer may be electrically connected to the electrode lead.

[0023] The secondary battery of the present invention has the effect of being able to estimate the internal oxygen concentration more accurately and conveniently.

[0024] The effects obtainable from the exemplary embodiments of the present invention are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure belong from the following description. That is, unintended effects resulting from the implementation of the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

[0025] FIG. 1 is a front view showing a lithium secondary battery according to one embodiment of the present invention.

[0026] FIG. 2 is a cross-sectional view showing an electrode stack according to one embodiment of the present invention.

[0027] FIG. 3 is a cross-sectional view showing an anode according to one embodiment of the present invention.

[0028] FIG. 4 is a cross-sectional view showing a cathode according to one embodiment of the present invention.

[0029] FIG. 5 is a schematic diagram of a lithium secondary battery showing a battery case and an O2 sensor layer according to one embodiment of the present invention.

[0030] FIG. 6 is a partial cross-sectional view showing a cross- section of the lithium secondary battery along the AA' line of FIG. 5.

[0031] FIG. 7 is a schematic diagram of a lithium secondary battery showing a battery case and an O2 sensor layer according to one embodiment of the present invention.

[0032] FIG. 8 is a partial cross-sectional view showing a cross- section of the lithium secondary battery along the BB' line of FIG. 7.

[0033] FIG. 9 is a schematic diagram of a lithium secondary battery showing a battery case and an O2 sensor layer according to one embodiment of the present invention.

[0034] FIG. 10 is a perspective view of a battery pack according to exemplary embodiments of the present invention.

[0035] FIG. 11 is a perspective view showing some elements of a battery pack according to exemplary embodiments of the present invention.

[0036] FIG. 12 is a diagram schematically showing the configuration of a vehicle according to one embodiment of the present invention.

[0037] Hereinafter, preferred embodiments of the concept of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the concept of the present invention may be modified in various different forms, and the scope of the concept of the present invention should not be interpreted as being limited by the embodiments described below. It is preferable to interpret the embodiments of the concept of the present invention as being provided to more completely explain the concept of the present invention to those with average knowledge in the art. Identical reference numerals denote identical elements throughout. Furthermore, various elements and areas in the drawings are depicted schematically. Accordingly, the concept of the present invention is not limited by the relative sizes or spacing depicted in the accompanying drawings.

[0038] Terms such as first, second, etc. may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the concept of the present invention, the first component may be named the second component, and conversely, the second component may be named the first component.

[0039] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the concept of the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, expressions such as "comprising" or "having" are intended to indicate the existence of the features, number, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, actions, components, parts, or combinations thereof.

[0040] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by those skilled in the art to which the concept of the present invention pertains. Furthermore, it will be understood that commonly used terms, such as those defined in advance, should be interpreted as having meanings consistent with their intent in the context of the relevant technology, and should not be interpreted in an overly formal sense unless explicitly defined herein.

[0041] Where an embodiment can be implemented differently, a specific process sequence may be performed differently from the order described. For example, two processes described in succession may be performed substantially simultaneously or in the reverse order of the description.

[0042] In the accompanying drawings, variations of the depicted shapes may be anticipated, for example, depending on manufacturing techniques and / or tolerances. Accordingly, embodiments of the present invention should not be interpreted as being limited to specific shapes of the areas depicted herein, but should include, for example, variations in shape resulting from the manufacturing process. All terms "and / or" used herein include each of the mentioned components and all combinations of one or more of them.

[0043]

[0044] (1st embodiment)

[0045] FIG. 1 is a front view showing a lithium secondary battery (1) according to one embodiment of the present invention.

[0046] Referring to FIG. 1, a lithium secondary battery (1) according to one embodiment of the present invention comprises a positive electrode, a negative electrode, and a battery case (150) in which the electrode stack is mounted. In some embodiments, the lithium secondary battery (1) may further comprise an electrolyte together with an electrode stack (not shown) inside the battery case (150). In some embodiments, the lithium secondary battery (1) may further comprise a solid electrolyte between the positive electrode and the negative electrode.

[0047] For example, the above electrolyte or solid electrolyte allows ions to move between the positive and negative electrodes, and through this ion exchange between the positive and negative electrodes, the lithium secondary battery (1) can perform charging and discharging. Examples of the electrolyte or solid electrolyte used in the present invention include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used when manufacturing a lithium secondary battery, but are not limited to these.

[0048] Additionally, the battery case (150) includes a sealing portion (155) of a structure sealed by heat fusion along the outer circumference. The battery case (150) may be a laminate sheet comprising a resin layer and a metal layer. In some embodiments, the battery case (150) is made of a laminate sheet and may consist of an outer resin layer forming the outermost layer, a barrier metal layer that prevents the penetration of material, and an inner resin layer for sealing. However, the embodiments of the present invention are not limited to the structure described above and may be replaced with a battery case of a secondary battery of another general structure.

[0049] Additionally, the electrode laminate (not shown) may be formed in a jelly-roll type (wound type), stack type (laminated type), or composite type (stack and folding type) structure. In some embodiments, the electrode laminate (not shown) may include an anode, a cathode, and a separator disposed between them.

[0050] In addition, in this embodiment, the battery case (150) may be structured such that an electrode lead (140), which is electrically connected to a plurality of electrode tabs (not shown) extending from an electrode stack (not shown), is exposed to the outside. More specifically, the electrode lead (140) may protrude outwardly from the battery case (150) through the sealing portion (155). In addition, in this embodiment, a lead film (160) may be positioned between the electrode lead (140) and the sealing portion (155).

[0051] The lead film (160) can not only prevent a short circuit from occurring between the electrode lead (140) and the blocking metal layer of the battery case (150), but also improve the sealing performance of the battery case (150). When the lead film (160) is provided, the phenomenon of reduced adhesion during thermal fusion between the metal electrode lead (140) and the polymer battery case (150) can be prevented. In addition, it is preferable that the lead film (160) be an insulating material capable of blocking the application of current from the electrode lead (140) to the battery case (150). The lead film (160) is made of a film having insulating and thermal fusion properties. The lead film (160) may include one or more layers of material selected from, for example, polyimide (PI), polypropylene, polyethylene, and polyethylene terephthalate (PET). In some embodiments, the length of the lead film (160) may be increased to also serve the function of preventing a short circuit in the portion of the electrode lead (140) exposed outside the battery case (150).

[0052] In some embodiments, the electrode lead (140) includes an anode lead (141) electrically connected to an anode tab included in the electrode stack and a cathode lead (145) electrically connected to a cathode tab included in the electrode stack.

[0053] In some embodiments, the lithium secondary battery (1) may be a bidirectional pouch battery cell in which a positive lead (141) and a negative lead (145) protrude from each side of the battery case (150). However, not limited thereto, the lithium secondary battery (1) may be a unidirectional pouch battery cell in which a positive lead (141) and a negative lead (145) are arranged together on the same side of the battery case (150). In other embodiments, the lithium secondary battery (1) may be a secondary battery in which an electrode stack is housed within a prismatic or cylindrical battery case.

[0054] Although the following description is based on bidirectional pouch battery cells, it may be described in the same or similar manner for unidirectional pouch battery cells. A person skilled in the art will understand that the following description is applicable to unidirectional pouch battery cells, prismatic secondary batteries, and cylindrical battery cases.

[0055]

[0056] FIG. 2 is a cross-sectional view showing an electrode stack (40) according to one embodiment of the present invention.

[0057] Referring to FIG. 2, the electrode stack (40) is formed by alternately stacking a positive electrode (10) and a negative electrode (20) with a separator (30) in between. At this time, the electrode stack (40) may be provided with electrode tabs, and the electrode tabs are connected to the positive electrode (10) and the negative electrode (20) of the electrode stack (40), respectively, and may protrude outward from the electrode stack (40). A plurality of electrode tabs connected to the positive electrode (10) and a plurality of electrode tabs connected to the negative electrode (20) may protrude from the electrode stack (40) in different directions and / or the same direction. The manufactured electrode stack (40) may be housed in a battery case (150). As previously described, the lithium secondary battery (1) including the electrode stack (40) may be manufactured in a pouch type, a prismatic type, or a cylindrical type.

[0058]

[0059] FIG. 3 is a cross-sectional view showing an anode (10) according to one embodiment of the present invention.

[0060] Referring to FIG. 3, the anode (10) is formed by coating a primer layer (12) and anode active material layers (13, 14) on both sides of an anode current collector (11). In some embodiments, the primer layer (12) may be applied to the surface of the anode current collector (11). In some embodiments, the primer layer (12) may have a patterned structure and may be provided on the surface of the anode current collector (11). In some embodiments, the entire surface of the anode current collector (11) may be coated with a dot pattern primer layer (12).

[0061] In FIG. 3, the positive active material layer provided on one surface of the positive current collector (11) is shown as being provided in two layers, but it may be provided in one layer. Also, in FIG. 3, the positive active material layer is shown as being provided on both surfaces of the positive current collector (11), but the positive active material layer may be provided on only one surface.

[0062] The above positive current collector (11) is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. The above positive current collector (11) may include, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc.

[0063] In some embodiments, the positive current collector (11) may form fine irregularities on its surface to increase adhesion with the active material described later. In some embodiments, the positive current collector (11) may have various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0064] In some embodiments, the positive current collector (11) may have a thickness of about 10 μm to about 25 μm, but the present invention is not limited thereto.

[0065] The above positive active material layers (13, 14) may include a first positive active material layer (13) and a second positive active material layer (14). The first positive active material layer (13) may be disposed on the primer layer (12). In some embodiments, the second positive active material layer (14) may be disposed on the first positive active material layer (13).

[0066] The first positive active material layer (13) comprises a first positive active material, and the second positive active material layer (14) may comprise a second positive active material. The first positive active material and the second positive active material may each independently comprise a positive active material as described below.

[0067] The above-mentioned positive electrode active material may comprise, for example, lithium transition metal oxide; lithium metal iron phosphate; lithium nickel-manganese-cobalt oxide; an oxide in which a portion of lithium nickel-manganese-cobalt oxide is substituted with another transition metal; or two or more of these, but is not limited thereto. Specifically, the above-mentioned positive electrode active material may comprise, for example, a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; and a compound with 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 LiNi 1-x Ni-site type lithium nickel oxide represented by MxO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); chemical formula LiMn 2-x M x 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); Li in which part of the Li of the chemical formula is substituted with aluminum ions. 1+x (Ni a Co b Mn c Al d ) 1-x Examples include O2 (x = 0 to 0.03, a = 0.3 to 0.95, b = 0.01 to 0.35, c = 0.01 to 0.5, d = 0.001 to 0.03, a+b+c+d=1); lithium metal phosphate LiMPO4 (where M is M = Fe, Co, Ni, or Mn), disulfide compounds; Fe2(MoO4)3, etc., but are not limited to these.

[0068] In some embodiments, the first positive active material and the second positive active material may be of the same type. In some embodiments, both the first positive active material and the second positive active material may comprise a lithium metal phosphate material.

[0069] In some embodiments, the first positive electrode active material and the second positive electrode active material may be different materials. In some embodiments, one of the first positive electrode active material and the second positive electrode active material may include a lithium metal phosphate material and the other may include a lithium nickel-manganese-cobalt oxide material.

[0070] The above positive active materials can be connected and fixed to each other by a positive binder.

[0071] The above-mentioned anode binder is adhesive, stable in electrochemical reactions, and capable of maintaining a stable form by binding electrode materials such as the anode active material and the anode conductive material, and is not limited to specific components.Non-limiting examples of such anode binders include styrene butadiene rubber (SBR), butadiene rubber (BR), nitrile butadiene rubber (NBR), styrene butadiene styrene block polymer (SBS), styrene ethylene butadiene block polymer (SEB), styrene-(styrene butadiene)-styrene block polymer, natural rubber (NR), isoprene rubber (IR), ethylene-propylene-diene terpolymer (EPDM), poly(ethylene-co-propylene-co-5-methylene-2-norbornene) polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polyvinyl chloride, and polyvinylidene fluoride-co-hexafluoropropylene. It may be polyvinylidene fluoride-co-trichloroethylene, polymethyl(meth)acrylate, polyethylhexylacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene, polypropylene, ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide, polypropylene oxide, polyarylate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, or may contain two or more of these.Specifically, the binder may include styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), polymethyl methacrylate, polyethylhexyl acrylate, and polybutyl acrylate. In a specific embodiment, the anode binder may include one or more selected from these.

[0072] The above positive active material may further include a positive conductive material to reduce electrical resistance.

[0073] The above-mentioned positive electrode conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery. Non-limiting examples include graphite such as natural graphite or artificial graphite; carbon black-based carbon compounds such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. In a specific embodiment, the above-mentioned positive electrode conductive material may include one or more selected from these.

[0074] In some embodiments, at least one of the first positive active material layer (13) and the second positive active material layer (14) may include a positive active material based on an iron phosphate compound.

[0075] In some embodiments, the content of the iron phosphate compound-based positive active material in the first positive active material layer (13) may be about 50 wt% or more based on the total weight of the first positive active material layer (13). In some embodiments, the first positive active material layer (13) may contain about 55 wt% or more, about 60 wt% or more, about 65 wt% or more, about 70 wt% or more, about 75 wt% or more, about 80 wt% or more, or about 85 wt% or more based on the total weight of the first positive active material layer (13).

[0076] In some embodiments, the content of the iron phosphate compound-based positive active material in the second positive active material layer (14) may be about 50 wt% or more based on the total weight of the second positive active material layer (14). In some embodiments, the second positive active material layer (14) may contain about 55 wt% or more, about 60 wt% or more, about 65 wt% or more, about 70 wt% or more, about 75 wt% or more, about 80 wt% or more, or about 85 wt% or more based on the total weight of the second positive active material layer (14).

[0077] The above positive active material layer (13, 14) may include a sacrificial positive material comprising a compound of the following chemical formula 1.

[0078] <Chemical Formula 1>

[0079] Li a Fe 1-x M x O y

[0080] (Here, 1 <a≤5, 0≤x≤0.35, 2<y≤4, M은 Ga, Zr, Ti, Mg, Ca, Ba, Sc, Mn, Zn, Cu, V, Cr, Sr, In, Al, 또는 그 조합임)

[0081] In some embodiments, the compound of Formula 1 may include Li5FeO4. In some embodiments, the compound of Formula 1 may include Li3FeO 3.5 It may include.

[0082] In some embodiments, the positive active material layer (13, 14) may further include LiFeO2. The content of LiFeO2 in the positive active material layer (13, 14) may be about 0.3 weight% to about 8 weight% based on the total weight of the positive active material layer (13, 14). In some embodiments, the content of LiFeO2 in the positive active material layer (13, 14) is about 0.3 wt% to about 8 wt%, about 0.5 wt% to about 7.8 wt%, about 0.7 wt% to about 7.5 wt%, about 1 wt% to about 7.3 wt%, about 1.3 wt% to about 7 wt%, about 1.5 wt% to about 6.8 wt%, about 1.7 wt% to about 6.5 wt%, about 2 wt% to about 6.3 wt%, about 2.3 wt% to about 6 wt%, about 2.5 wt% to about 5.8 wt%, about 2.7 wt% to about 5.5 wt%, about 3 wt% to about 5.3 wt%, about 3.3 wt% to about 5 wt%, about 3.5 wt% to about 3.5 wt% to about 5 wt%, based on the total weight of the positive active material layer (13, 14). It may have a range of 4.8 wt%, about 3.7 wt% to about 4.5 wt%, about 4 wt% to about 4.3 wt%, or between any two of these figures.

[0083] If the content of LiFeO2 in the positive active material layer (13, 14) is too low, the charging capacity of the lithium secondary battery (1) may decrease. If the content of LiFeO2 in the positive active material layer (13, 14) is too high, the electrical resistance of the positive active material layer (13, 14) may increase excessively.

[0084]

[0085] FIG. 4 is a cross-sectional view showing a cathode (20) according to one embodiment of the present invention.

[0086] Referring to FIG. 4, the cathode (20) is formed by coating cathode active material layers (22, 23) on both sides of a cathode current collector (21).

[0087] In FIG. 4, the negative active material layer provided on one surface of the negative current collector (21) is shown as being provided in two layers, but it may be provided in one layer. Also, in FIG. 4, the negative active material layer is shown as being provided on both surfaces of the negative current collector (21), but the negative active material layer may be provided on only one surface.

[0088] The above negative current collector (21) is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. The above negative current collector (21) may be, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, a copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy.

[0089] In some embodiments, the negative current collector (21) may form fine irregularities on its surface to increase the bonding strength with the negative active material described later. In some embodiments, the negative current collector (21) may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0090] In some embodiments, the negative current collector (21) may have a thickness of about 1 μm to about 100 μm, but the present invention is not limited thereto.

[0091] In some embodiments, the negative active material layer (22, 23) may include a first negative active material layer (22) and a second negative active material layer (23).

[0092] The first cathode active material layer (22) and the second cathode active material layer (23) may each independently include a cathode active material as described below.

[0093] The above-mentioned cathode active material is carbon, for example, graphite-based carbon such as non-graphitized carbon, natural graphite, or artificial graphite; Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me y O z (wherein Me is one or more of Mn, Fe, Pb, and Ge, and Me' is one or more of Al, B, P, Si, elements of Group 1, Group 2, and Group 3 of the periodic table, and halogens, and 0 <x≤1, 1≤y≤3, 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SiO, SiO / C, SiO2등의 실리콘계 산화물; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료 등을 사용할 수 있으나, 이들만으로 한정되는 것은 아니다.

[0094] In some embodiments, the negative electrode active material may be a Si-based negative electrode active material and may include one or more of, for example, Li2SiO3, Li2Si2O5, Li3SiO3, and Li4SiO4.

[0095] In some embodiments, the negative electrode active material may include a Si-based negative electrode active material containing carbon. Specifically, the negative electrode active material may further include a carbon coating layer on the particle surface. In this case, the amount of the carbon coating may be 20% by weight or less, preferably about 1% to about 20% by weight, based on the total weight of the silicon-based negative electrode active material.

[0096] Referring again to FIG. 2, the electrode stack (40) may include a separator (30) between the positive electrode (10) and the negative electrode (20).

[0097] In some embodiments, the separator (30) separates the positive electrode (10) and the negative electrode (20) and provides a passage for the movement of lithium ions, and can be used without special limitations as long as it is a separator typically used in lithium-ion secondary batteries. In particular, it is desirable that the separator (30) has low resistance to the movement of ions of the electrolyte and excellent electrolyte retention capacity.

[0098] Specifically, a porous polymer film, such as a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used as the separator (30). Alternatively, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used as the separator (30). Additionally, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and the separator (30) may have a single-layer or multi-layer structure. In some embodiments, the separator (30) may include a safety reinforced separator (SRS) with a thin coating of a ceramic material on its surface.

[0099] In addition, conventional porous nonwoven fabrics, such as high-melting-point glass fibers, polyethylene terephthalate fibers, etc., may be used as the separation membrane (30), but are not limited thereto.

[0100] However, if the lithium secondary battery (1) described with reference to FIG. 1 is a solid-state secondary battery, the separator (30) may be omitted.

[0101] Referring again to FIG. 1, the lithium secondary battery (1) may further include an electrolyte.

[0102] The above electrolyte may be one or more mixed organic solvents selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), gamma butyrolactone (GBL), fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate, and butyl propionate.

[0103] In some embodiments, the electrolyte may further comprise a lithium salt, and the anion of the lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , F3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2- , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It may be one or more selected from a group consisting of

[0104] In some embodiments, the electrolyte may comprise a lithium salt, an organic solvent, and a coumarin-based additive. The electrolyte comprising the coumarin-based additive can effectively remove oxygen gas generated from the sacrificial cathode material.

[0105]

[0106] FIG. 5 is a schematic diagram of a lithium secondary battery (1) showing a battery case (150) and an O2 sensor layer (180a) according to one embodiment of the present invention. FIG. 6 is a partial cross-sectional view showing a cross- section of the lithium secondary battery (1) along the line AA' of FIG. 5.

[0107] Referring to FIGS. 5 and 6, an O2 sensor layer (180a) may be provided inside the battery case (150). The O2 sensor layer (180a) may include a material that changes its electrical properties by reacting with oxygen (O2).

[0108] In some embodiments, the O2 sensor layer (180a) may be provided between the sealing portion (155) of the battery case (150) and the electrode stack (40). In some embodiments, the battery case (150) may be a pouch case, and the O2 sensor layer (180a) may be provided between the sealing portion of the pouch case and the electrode stack (40).

[0109] In some embodiments, a portion of the O2 sensor layer (180a) may be located in the sealing portion (155), and the remaining portion of the O2 sensor layer (180a) may be located between the sealing portion (155) and the electrode laminate (40). That is, a portion of the O2 sensor layer (180a) may be interposed between the two ends of the pouch case that are joined at the sealing portion (155). A portion of the O2 sensor layer (180a) may extend in the width direction (horizontal direction in FIG. 6) of the sealing portion (155). In some embodiments, the O2 sensor layer (180a) may extend in the width direction over a portion of the width of the sealing portion (155) at the sealing portion (155).

[0110] In some embodiments, the O2 sensor layer (180a) may be extended along the long side of the sealing portion (155) in the longitudinal direction of the long side (horizontal direction in FIG. 5). Although FIG. 5 shows a single O2 sensor layer (180a) extended, the present invention is not limited thereto. In some embodiments, the O2 sensor layer (180a) may be extended along the long side of the sealing portion (155) for a length of less than half the length of the long side, for example, 1 / 2 to 1 / 30 of the length of the long side. In some embodiments, the O2 sensor layer (180a) may include a plurality of short O2 sensor layers arranged side by side along the long side of the sealing portion (155).

[0111] In some embodiments, the O2 sensor layer (180a) may extend along the inner surface of the battery case (150). In some embodiments, the O2 sensor layer (180a) may extend from the sealing portion (155) toward the interior of the battery case (150) and then extend along the inner surface of the battery case (150).

[0112] In some embodiments, the O2 sensor layer (180a) may comprise zirconia (ZrO2). In some embodiments, the ZrO2 of the O2 sensor layer (180a) may have a tetragonal crystal structure.

[0113] In some embodiments, the O2 sensor layer (180a) may be doped with a dopant. The dopant may include one or more selected from the group consisting of, for example, calcium (Ca), magnesium (Mg), and yttria.

[0114] In some embodiments, the concentration of the dopant in the O2 sensor layer (180a) may be about 3 wt% to about 8 wt%. In some embodiments, the concentration of the dopant in the O2 sensor layer (180a) may be about 3 wt% to about 8 wt%, about 4 wt% to about 7 wt%, about 5 wt% to about 6 wt%, or a range between any two of these values.

[0115] If the dopant concentration in the O2 sensor layer (180a) is too low, the sensitivity for sensing O2 may be insufficient. If the dopant concentration in the O2 sensor layer (180a) is too high, the crystal structure may collapse during the manufacturing process of the O2 sensor layer (180a), resulting in insufficient mechanical strength.

[0116] When oxygen is generated within the battery case (150), the electrical characteristics of the O2 sensor layer (180a) may change. By preparing the electrical characteristics of the O2 sensor layer (180a) in an environment where oxygen is absent and comparing this with the electrical characteristics of the O2 sensor layer (180a) within the battery case (150), it is possible to estimate whether oxygen is present within the battery case (150) and the concentration of the oxygen present.

[0117]

[0118] (2nd Example)

[0119] FIG. 7 is a schematic diagram of a lithium secondary battery (1b) showing a battery case (150) and an O2 sensor layer (180b) according to one embodiment of the present invention. FIG. 8 is a partial cross-sectional view showing a cross- section of the lithium secondary battery (1b) along the line BB' of FIG. 7.

[0120] Referring to FIGS. 7 and 8, an O2 sensor layer (180b) may be provided inside the battery case (150). The O2 sensor layer (180b) may include a material that changes its electrical properties by reacting with oxygen (O2).

[0121] In some embodiments, the O2 sensor layer (180b) may be electrically connected to the electrode lead (140). In some embodiments, one end (182) of the O2 sensor layer (180b) may be configured to be in physical contact with the electrode lead (140). In some embodiments, one end (182) of the O2 sensor layer (180b) may extend outside the battery case (150) while in physical contact with the electrode lead (140).

[0122] In some embodiments, when one end (182) of the O2 sensor layer (180b) is in physical contact with the electrode lead (140), the one end (182) of the O2 sensor layer (180b) may be provided between the electrode lead (140) and the short side of the sealing portion (155). In some embodiments, the one end (182) of the O2 sensor layer (180b) may be provided between the electrode lead (140) and the lead film (160).

[0123] In some other embodiments, one end (182) of the O2 sensor layer (180b) may be in physical contact with the electrode lead (140) but may not extend outside the battery case (150). In this case, the one end (182) of the O2 sensor layer (180b) may remain inside the battery case (150) while in physical contact with the electrode lead (140). In some embodiments, the one end (182) of the O2 sensor layer (180b) may be terminated inside the battery case (150) beyond the short side of the sealing portion (155). In some embodiments, the one end (182) of the O2 sensor layer (180b) may be terminated within the short side of the sealing portion (155).

[0124] In some embodiments, the end (182) of the O2 sensor layer (180b) may extend along the inner surface of the battery case (150) after contacting the electrode lead (140). In some embodiments, the O2 sensor layer (180b) may extend from the short side of the sealing portion (155) toward the interior of the battery case (150) and then extend along the inner surface of the battery case (150) while avoiding the electrode stack (40).

[0125] In some embodiments, a portion of the O2 sensor layer (180b) may be extended and exposed to the outside of the battery case (150) through the sealing portion (155). In some embodiments, the other end (181) of the O2 sensor layer (180b) may be extended and exposed to the outside of the battery case (150) through the sealing portion (155). In some embodiments, the other end (181) of the O2 sensor layer (180b) may be extended and exposed to the outside of the battery case (150) through the long side of the sealing portion (155).

[0126] In some embodiments, the O2 sensor layer (180b) may include a conductive electrode on the surface of the other end (181).

[0127] In some embodiments, the electrical characteristics of the O2 sensor layer (180b) can be investigated by connecting (i) an electrode lead (140) electrically connected to one end (182) of the O2 sensor layer (180b) and (ii) the other end (181) of the O2 sensor layer (180b) exposed outside the battery case (150) to two probes of a measuring device, respectively.

[0128] In some embodiments, the electrical characteristics of the O2 sensor layer (180b) can be investigated by connecting (i) one end (182) of the O2 sensor layer (180b) exposed to the outside through the short side of the sealing portion (155) and (ii) the other end (181) of the O2 sensor layer (180b) exposed to the outside of the battery case (150) to two probes of a measuring device, respectively.

[0129] In the embodiment described with reference to FIGS. 7 and 8, the electrical characteristics of the O2 sensor layer (180b) can be measured by directly contacting a probe from the outside, so the oxygen concentration inside the battery case (150) can be estimated more accurately and conveniently.

[0130]

[0131] (3rd Example)

[0132] FIG. 9 is a schematic diagram of a lithium secondary battery (1c) showing a battery case (150) and an O2 sensor layer (180c) according to one embodiment of the present invention.

[0133] Referring to FIG. 9, the O2 sensor layer (180c) may be provided between the sealing portion (155) of the battery case (150) and the electrode stack (40). In some embodiments, a portion of the O2 sensor layer (180c) may be located in the sealing portion (155), and the remaining portion of the O2 sensor layer (180c) may be located between the sealing portion (155) and the electrode stack (40). That is, a portion of the O2 sensor layer (180c) may be interposed between the two ends of the pouch case that are joined at the sealing portion (155). A portion of the O2 sensor layer (180c) may extend from the sealing portion (155) in the width direction of the sealing portion (155) (vertical direction in FIG. 9). In some embodiments, the O2 sensor layer (180c) may extend in the width direction over a portion of the width of the sealing portion (155) in the sealing portion (155).

[0134] In some embodiments, the O2 sensor layer (180c) may be extended along the long side of the sealing portion (155) in the longitudinal direction of the long side (horizontal direction in FIG. 9). Although FIG. 9 shows a single O2 sensor layer (180c) extended, the present invention is not limited thereto.

[0135] In some embodiments, one end (182) and the other end (181) of the O2 sensor layer (180c) may be exposed to the outside. In some embodiments, one end (182) and the other end (181) of the O2 sensor layer (180c) may be exposed to the outside of the battery case (150) at the long side of the sealing portion (155). The portion between one end (182) and the other end (181) of the O2 sensor layer (180c) may be substantially the same as the embodiment described with reference to FIGS. 5 and 6.

[0136] In some embodiments, the electrical characteristics of the O2 sensor layer (180c) can be investigated by connecting one end (182) and the other end (181) of the O2 sensor layer (180c) to two probes of a measuring device, respectively.

[0137] In the embodiment described with reference to FIG. 9, the electrical characteristics of the O2 sensor layer (180c) can be measured by directly contacting a probe from the outside, so the oxygen concentration inside the battery case (150) can be estimated more accurately and conveniently.

[0138]

[0139] (Fourth Example)

[0140] FIG. 10 is a perspective view of a battery pack (2) according to exemplary embodiments of the present invention. FIG. 11 is a perspective view showing some elements of a battery pack (2) according to exemplary embodiments of the present invention.

[0141] Referring to FIGS. 10 and 11, the battery pack (2) may include a lower case (211), secondary batteries (200), a center beam (213), a cross beam (216), a plurality of exhaust devices (214), a pack gasket (265), and an upper case (217). The battery pack (2) may be the final form of a battery system mounted on a mobility device, etc. Additionally, the secondary batteries (200) may be one or more of the secondary batteries (1, 1b, 1c) described with reference to FIGS. 1 and FIGS. 5 to 9.

[0142] The pack housing (201) defining the exterior of the battery pack (2) may include the lower case (211) and the upper case (217).

[0143] The lower case (211) may provide an internal space (219) for mounting a plurality of secondary batteries (200). In some embodiments, the lower case (211) may include a plate portion (211P) and a side wall (211S). Two directions substantially parallel to the plate portion (211P) are defined as a first direction (e.g., Z-axis direction) and a second direction (e.g., Y-axis direction), and a direction substantially perpendicular to the plate portion (211P) of the lower case (211) is defined as a third direction (e.g., X-axis direction).

[0144] A plurality of secondary batteries (200) may be disposed on a plate portion (211P) of a lower case (211). The plate portion (211P) may support the plurality of secondary batteries (200). The plate portion (211P) may include substantially parallel upper and lower surfaces. The upper surface of the plate portion (211P) may face the plurality of secondary batteries (200). The lower surface of the plate portion (211P) is the opposite side of the upper surface of the plate portion (211P).

[0145] The above side wall (211S) can horizontally surround a plurality of secondary batteries (200). The above side wall (211S) can protect a plurality of secondary batteries (200) from the side. The side wall (211S) may include a first side wall (211-1), a second side wall (211-2), a third side wall (211-3), and a fourth side wall (211-4). The first to fourth side walls (211-1, 211-2, 211-3, 211-4) may be fixed to each other by a method such as friction stir welding, spot welding, etc., and are not particularly limited.

[0146] The first and second side walls (211-1, 211-2) may be substantially perpendicular to the second direction (e.g., the Y-axis direction). The third and fourth side walls (211-3, 211-4) may be substantially perpendicular to the first direction (e.g., the Z-axis direction). In some embodiments, the first and second side walls (211-1, 211-2) may cover the sides of the plate portion (211P). In some embodiments, the third and fourth side walls (211-3, 211-4) may be disposed on the plate portion (211P).

[0147] In some embodiments, the first to fourth sidewalls (211-1, 211-2, 211-3, 211-4) may be provided by an extrusion process. According to exemplary embodiments, the first to fourth sidewalls (211-1, 211-2, 211-3, 211-4) may include an internal void space, and accordingly, the sidewall (211S) may be lightweight. According to exemplary embodiments, the void space of the first to fourth sidewalls (211-1, 211-2, 211-3, 211-4) may be either a gas venting path or a coolant channel.

[0148] Hereinafter, the technical concept of the present invention is explained with reference to an embodiment in which each of the plurality of secondary batteries (200) does not include a module frame. However, this is a non-limiting example and does not limit the technical concept of the present invention in any sense. A person skilled in the art will be able to easily arrive at a battery pack in which battery modules including a module frame that exposes one edge of the battery cells are employed, based on what is described herein.

[0149] The center beam (213) can isolate elements mounted on the lower case (211) from one another. Accordingly, the center beam (213) can protect multiple secondary batteries (200) while preventing unwanted short circuits between them.

[0150] The center beam (213) may extend between the third and fourth side walls (211-3, 211-4). The center beam (213) may extend in a first direction (e.g., the Z-axis direction). The center beam (213) may be in contact with the third side wall (211-3) and the fourth side wall (211-4). The center beam (213) may isolate a plurality of secondary batteries (200) from one another. The center beam (213) may be interposed between a plurality of secondary batteries (200). In some embodiments, the center beam (213) may divide the internal space (219) into two regions in a second direction (e.g., the Y-axis direction).

[0151] In some embodiments, the cross beam (216) may be provided to divide the internal space (219) into two or more regions in a first direction (e.g., the Z-axis direction). The cross beam (216) may additionally isolate elements isolated by the center beam (213).

[0152] Some cross beams (216) may extend in a second direction (e.g., in the Y-axis direction) between the center beam (213) and the first side wall (211-1). Other cross beams (216) may extend in a second direction (e.g., in the Y-axis direction) between the center beam (213) and the second side wall (211-2). In some embodiments, the cross beams (216) may be provided to define a space in which a stack of a secondary battery or a group of secondary batteries is accommodated.

[0153] The arrangement of the center beam (213), cross beam (216), and plurality of secondary batteries (200) disclosed in FIGS. 10 and 11 is a non-limiting example and does not limit the technical concept of the present invention in any sense. A person skilled in the art will be able to easily arrive at a battery pack including various arrangements and numbers of center beams and battery cells based on what is described herein.

[0154] In some embodiments, a plurality of exhaust devices (214) may be coupled to the fourth side wall (211-4). The fourth side wall (211-4) may include a plurality of exhaust holes connected to the plurality of exhaust devices (214). The plurality of exhaust holes may be configured to provide a path for discharging gas and heat inside the battery pack (2).

[0155] A plurality of exhaust devices (214) may be configured to delay thermal propagation by releasing high-temperature gas inside the battery pack (2) to the outside when at least one of the plurality of secondary batteries (200) is in a thermal runway state.

[0156] Here, thermal runaway of multiple secondary batteries (200) is a state in which a temperature change of multiple secondary batteries (200) further accelerates the temperature change, and is an uncontrollable positive feedback. Multiple secondary batteries (200) in a thermal runaway state exhibit a rapid temperature rise and can emit a large amount of high-pressure gas and combustion residue.

[0157] The battery pack (2) may further include electrical components. In some embodiments, the electrical components may be mounted on the lower case (211). In some embodiments, the electrical components may be positioned between a fourth side wall (211-4) where exhaust devices (214) are installed and a plurality of secondary batteries (200). In some embodiments, the electrical components may include any electronic components necessary to drive the battery pack.

[0158] In some embodiments, the electrical components may include, for example, a battery management system (BMS). The BMS may be configured to perform monitoring, balancing, and control of the battery pack. In some embodiments, monitoring of the battery pack (2) may include measuring the voltage and current of a specific battery cell among a plurality of secondary batteries (200) and measuring the temperature of set locations within the battery pack (2). In some embodiments, the battery pack (2) may include measuring instruments for measuring the voltage, current, and temperature described above.

[0159] Balancing of the battery pack (2) is an operation that reduces deviations between multiple secondary batteries (200). Control of the battery pack (2) includes preventing overcharging, over-discharging, and overcurrent. Through monitoring, balancing, and control, the battery pack (2) can operate under optimal conditions, and accordingly, the shortening of the lifespan of each of the multiple secondary batteries (200) can be prevented or reduced.

[0160] The above electrical components may further include a cooling device, a PRA (power relay assembly), a safety plug, etc. The cooling device may include a cooling fan. The cooling fan can prevent overheating of each of the multiple secondary batteries (200) by circulating air inside the battery pack (2). The PRA may be configured to supply or cut off power from the high-voltage battery to an external load (e.g., a vehicle motor). The PRA can protect the multiple secondary batteries (200) and the external load (e.g., a vehicle motor) by cutting off power supply to the external load (e.g., a vehicle motor) in situations where abnormal voltage occurs, such as a voltage surge.

[0161] The battery pack (2) may further include a plurality of busbars configured to electrically connect a plurality of secondary batteries (200). The plurality of secondary batteries (200) may be connected in series and / or parallel by the plurality of busbars. Accordingly, the battery pack (2) may be configured to output a high voltage to an external load (e.g., a vehicle motor).

[0162] The gasket (265) may include a material that has elasticity in response to applied pressure. The gasket (265) may include rubber synthesized from a material such as EPDM (ethylene-propylene diene monomer). When the lower case (211) and the upper case (217) are combined, the gasket (265) may be interposed between the lower case (211) and the upper case (217). The lower case (211) and the upper case (217) may press the gasket (265) to cause some deformation in the gasket (265). Accordingly, the battery pack (2) can be sealed, and external fluid can be blocked from the internal space of the battery pack (2).

[0163] The upper case (217) may be coupled to the lower case (211). In some embodiments, the upper case (217) may include a main surface and an edge portion. The main surface may cover elements mounted in the battery pack (2), such as a plurality of secondary batteries (200) and electrical components. The edge portion is a surface that contacts the lower case (211). In some embodiments, the upper case (217) may have a flat shape, in which case the edge portion may horizontally surround the main surface. In some embodiments, the main surface may be elevated relative to the edge portion, and the edge portion and the main surface may be connected by a curved portion.

[0164]

[0165] (5th Example)

[0166] FIG. 12 is a diagram schematically showing the configuration of a vehicle according to one embodiment of the present invention.

[0167] Referring to FIG. 12, a vehicle (V) according to one embodiment of the present invention may include a battery pack (2) according to one embodiment of the present invention as described above. Here, the vehicle (V) may include a specific vehicle that uses electricity as a driving source, such as an electric vehicle or a hybrid vehicle. In addition, the vehicle (V) may further include various other components included in the vehicle, such as a vehicle body or a motor, in addition to the battery pack (2) according to the present invention.

[0168] The battery pack (2) can be installed at a designated location within the vehicle (V). The battery pack (2) can be used as an electric energy source to drive the vehicle (V) by providing driving force to the motor of the electric vehicle. In this case, the battery pack (2) can have a high nominal voltage of 100V or more.

[0169] The battery pack (2) may be charged or discharged by an inverter depending on the operation of a motor and / or internal combustion engine. The battery pack (2) may be charged by a regenerative charging device combined with a brake. The battery pack (2) may be electrically connected to the motor of the vehicle (V) through an inverter.

[0170]

[0171] As described above, although embodiments of the present invention have been described in detail, a person skilled in the art to which the present invention pertains will be able to modify and implement the present invention in various ways without departing from the spirit and scope of the present invention as defined in the appended claims. Therefore, future modifications to the embodiments of the present invention will not depart from the technology of the present invention.

[0172]

[0173] [Explanation of the symbol]

[0174] 1, 1b, 1c: Lithium secondary battery

[0175] 2: Battery Pack

[0176] 10: Anode

[0177] 11: Positive current collector

[0178] 12: Primer layer

[0179] 13: First positive active material layer

[0180] 14: Second positive electrode active material layer

[0181] 20: Cathode

[0182] 21: Cathode current collector

[0183] 22: First cathode active material layer

[0184] 23: Second negative electrode active material layer

[0185] 30: Separator

[0186] 40: Electrode assembly

[0187] 140: Electrode Lead

[0188] 141: Positive lead

[0189] 145: Cathode Lead

[0190] 150: Battery case

[0191] 155: Sealing part

[0192] 160: Lead film

[0193] 180a, 180b, 180c: O2 sensor layer

[0194] 200: Secondary battery

[0195] 201: Pack Housing

[0196] 211: Lower case

[0197] 213: Center beam

[0198] 214: Exhaust system

[0199] 216: Cross Beam

[0200] 217: Upper case

[0201] 265: Pack gasket

Claims

1. An electrode laminate comprising an anode, a cathode, and a separator provided between the anode and the cathode; A battery case surrounding the above electrode stack; An electrode lead electrically connected to the positive electrode or the negative electrode and extending to the outside of the battery case; and O2 sensor layer provided inside the above battery case; Includes, The above O2 sensor layer is a lithium secondary battery comprising a material that changes its electrical properties upon reacting with O2.

2. In Paragraph 1, A lithium secondary battery characterized in that the above O2 sensor layer comprises zirconia (ZrO2).

3. In Paragraph 1, A lithium secondary battery characterized in that the battery case is a pouch case, and the O2 sensor layer is provided between the sealing portion of the pouch case and the electrode laminate.

4. In Paragraph 3, A lithium secondary battery characterized in that the above O2 sensor layer is provided on the inner surface of the pouch case.

5. In Paragraph 4, A lithium secondary battery characterized in that the above O2 sensor layer is configured to extend from the inner surface of the pouch case and be electrically connected to the electrode lead.

6. In Paragraph 5, A lithium secondary battery characterized in that the above O2 sensor layer is configured to physically contact the electrode lead.

7. In Paragraph 5, A lithium secondary battery characterized in that one end of the O2 sensor layer is physically in contact with the electrode lead, and the other end of the O2 sensor layer is exposed to the outside through the sealing portion.

8. In Paragraph 3, A lithium secondary battery characterized in that the above O2 sensor layer is provided between the electrode lead and the sealing portion.

9. In Paragraph 1, A lithium secondary battery characterized in that the positive electrode comprises a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer comprises LiFeO2.

10. In Paragraph 9, A lithium secondary battery characterized in that the above-mentioned positive active material layer further comprises a sacrificial positive material which is a compound of Chemical Formula 1. <Chemical Formula 1> Li a Feb 1-x M x O y (Here, 1 <a≤5, 0≤x≤0.35, 2<y≤4, M은 Ga, Zr, Ti, Mg, Ca, Ba, Sc, Mn, Zn, Cu, V, Cr, Sr, In, Al, 또는 그 조합임) 11. In Paragraph 9, A lithium secondary battery characterized in that the content of LiFeO2 in the positive active material layer is 0.3% to 8% by weight based on the total weight of the positive active material layer.

12. A positive electrode comprising a positive current collector and a positive active material layer disposed on the positive current collector and comprising LiFeO2; and A cathode comprising a cathode current collector and a cathode active material layer disposed on the cathode current collector; A battery case surrounding the above positive and negative electrodes; and An O2 sensor layer comprising zirconia (ZrO2) provided inside the above battery case; Includes, The ZrO2 in the above O2 sensor layer is a lithium secondary battery having a tetragonal crystal structure.

13. In Paragraph 12, A lithium secondary battery characterized in that the above O2 sensor layer comprises about 3 wt% to about 8 wt% of a dopant.

14. In Paragraph 13, A lithium secondary battery characterized in that the dopant of the above O2 sensor layer comprises one or more types selected from the group consisting of calcium, magnesium, and yttria.

15. In Paragraph 12, It further includes an electrode lead that is electrically connected to the positive electrode or the negative electrode and extends to the outside of the battery case, A lithium secondary battery characterized in that the above O2 sensor layer is electrically connected to the above electrode lead.

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