Cathode and secondary battery comprising same

Abstract

The present invention relates to a cathode and a secondary battery comprising same. The cathode comprises a lithium-rich compound represented by chemical formula 2, and thus can compensate for irreversible capacity loss occurring in an anode during initial charging and discharging, and a decrease in electrical conductivity due to the compound is reduced such that charging and discharging capacity characteristics are excellent. In addition, the cathode suppresses oxygen generation during charging and discharging, and thus a secondary battery comprising same has high safety and excellent cycle characteristics and lifetime characteristics.

Description

Anode and secondary battery including the same

[0001] The present invention relates to a positive electrode and a secondary battery including the same.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0016196 dated February 7, 2025, and all contents disclosed in the document of said patent application are incorporated herein as part of this specification.

[0003]

[0004] Recently, lithium-ion batteries are being widely applied not only to small devices such as portable electronic devices but also to medium-to-large devices such as battery packs or power storage systems for hybrid and electric vehicles. In particular, with the recent increase in concern for environmental issues, the demand base for high-capacity batteries is expanding due to the growth of the market for devices employing high-capacity batteries, such as electric vehicles and hybrid electric vehicles, which can replace fossil fuel-using vehicles like gasoline and diesel cars—a major cause of air pollution. To manufacture lithium-ion batteries that serve as the power source for these devices, there is a demand for high-capacity electrode designs that possess high energy density, high output, and high discharge voltage.

[0005] There are various research directions for increasing the capacity of such lithium secondary batteries, such as using non-carbon-based anode materials like silicon, which have a higher energy density than graphite, developing and using new cathode materials, or developing lithium metal batteries that utilize lithium metal as the anode.

[0006] However, these high-capacity lithium secondary batteries have the problem of high lithium consumption and significant irreversible capacity loss during initial charging and discharging. More specifically, during the initial charging and discharging process of lithium secondary batteries, lithium ions migrate to the negative electrode and cause side reactions, forming an SEI layer. Since high-capacity lithium secondary batteries consume a particularly large amount of lithium for processes such as the formation of this SEI layer, they have the disadvantage of increased irreversible capacity loss.

[0007] Previously, methods such as pre-lithiation or the application of lithium alloys were considered to compensate for lithium ion consumption and irreversible capacity loss, but these methods were found to be difficult to apply to the manufacture of commercially available batteries. Consequently, the most widely used method recently involves adding a lithium-rich metal oxide as an additive to the existing cathode active material to compensate for the irreversible capacity loss of the anode.

[0008] Various materials such as Li2NiO2, Li6CoO4, or Li5FeO4 are known as such cathode additives, and among them, the application of Li5FeO4 is being widely considered due to factors such as its relatively low cost.

[0009] However, the aforementioned Li5FeO4 has low electrical conductivity, which may result in insufficient compensation for irreversible capacity. Consequently, there is a limitation in that a significant amount of Li5FeO4 must be used to compensate for large irreversible capacity in high-capacity, next-generation lithium-ion batteries. Furthermore, Li5FeO4 remains in the positive active layer even after subsequent charge-discharge cycles, generating a significant amount of oxygen (O2) gas. This generated oxygen gas increases the internal pressure of the battery cell, which can deform and / or damage the battery case during use, thereby reducing the safety of the battery. In addition, the oxygen gas can form gas traps at the interface between the positive and / or negative electrodes, interfering with the electrochemical reactions of the electrodes or damaging the active layers of each electrode. Consequently, this can act as a factor that reduces the cycle and lifespan characteristics of the secondary battery, which is why the commercialization of Li5FeO4 is being delayed.

[0010]

[0011] [Prior Art Literature]

[0012] [Patent Literature]

[0013] Republic of Korea Published Patent Application No. 10-2023-0057858

[0014]

[0015] The objective of the present invention is to provide a positive electrode and a secondary battery including the same, which can compensate for initial irreversible capacity loss at the negative electrode while improving lifespan and cycle characteristics.

[0016]

[0017] In order to solve the aforementioned problem,

[0018] The present invention is,

[0019] Positive current collector,

[0020] A first layer provided on at least one surface of the anode current collector and comprising a first anode additive and a second anode additive, and

[0021] It includes a second layer provided on the first layer and comprising a positive electrode active material, and

[0022] The first anode additive comprises a compound in which the ratio of the activation voltage range overlapping with the operating voltage range of the anode active material is 50% or more based on the operating voltage of the anode active material, and

[0023] The above second anode additive comprises one or more compounds represented by the following chemical formula 1, and

[0024] The present invention provides an anode characterized in that the average particle size of the second anode additive is smaller than the average particle size of the first anode additive:

[0025] [Chemical Formula 1]

[0026] M 1 x M 2 y O z

[0027] (In the above chemical formula 1,

[0028] M 1 and M 2 are Li, W, Mo, Ni, Co, Nb, Ge, Ti, Ta, or Ce, respectively, where M 1 and M 2 It contains different metals,

[0029] x, y, and z are 1≤x≤3, 0≤y≤1, and 1≤z≤6, respectively.

[0030] At this time, the average particle size (D of the first anode additive) 50 ) may be in the range of 0.5㎛ to 20㎛.

[0031] The average particle size of the second anode additive may have a range ratio of 0.5 or more and less than 1.0 based on the average particle size of the first anode additive.

[0032] The above first anode additive may include one or more of the compounds represented by the following chemical formula 2:

[0033] [Chemical Formula 2]

[0034] Li a M 3 (1-b) M 4 b O c

[0035] In the above chemical formula 2,

[0036] M 3 is Fe, Co, Mn, Zn, Al, or Ga, and

[0037] M 4 is at least one metal selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Co, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, wherein M 3 and M 4 It includes different metals,

[0038] a, b, and c are 1≤a≤7, 0≤b≤0.5, and 1.8≤c≤4.5, respectively.

[0039] The first anode additive may be included in a range of 0.5% to 5% by weight based on the total weight of the first layer and the second layer.

[0040] The second anode additive may be included in a range of 5% to 25% by weight based on the total weight of the first anode additive.

[0041] The first layer may further comprise a third anode additive comprising at least one of a metal carbonate; a metal halide; a photosensitive dye; an unsaturated hydrocarbon; a polymer having repeating units including an amide group; catechols; sulfites; an ascorbic acid derivative; and an enzyme.

[0042] At this time, the metal carbonate or metal halide may include at least one metal among iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu).

[0043] The above third anode additive may be included in an amount of 1 to 25 parts by weight based on 100 parts by weight of the first anode additive.

[0044] The average thickness of the first layer may be in the range of 1㎛ to 30㎛.

[0045] The average thickness of the first layer may be in the range of 0.05 to 1 as a ratio to the average thickness of the second layer.

[0046] The first layer above may further include a positive electrode active material.

[0047] The positive electrode active material included in the first layer and the second layer may each include a lithium iron phosphate compound represented by the following chemical formula 3:

[0048] [Chemical Formula 3]

[0049] LiFe r M 5 (1-r) XO4

[0050] (In the above chemical formula 3,

[0051] M 5 is at least one element selected from W, Cu, Fe, V, Cr, CO, Ni, Mn, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and

[0052] X is at least one element among P, Si, S, As, and Sb, and

[0053] r is 0≤r≤0.9).

[0054]

[0055] The present invention is,

[0056] An electrode assembly comprising an anode, a cathode, and a separator interposed between the anode and the cathode according to the present invention as described above, and

[0057] A secondary battery comprising an electrolyte composition that impregnates the electrode assembly is provided.

[0058] At this time, the cathode may include a cathode active layer comprising a carbon-based cathode active material on at least one surface of the cathode current collector.

[0059] The above cathode active layer is made of Si, SiC, and SiO q (However, 0.5≤q≤2.5) may further include one or more silicon-based negative electrode active materials.

[0060]

[0061] The anode according to the present invention includes a lithium-over-compound represented by Formula 2, which can compensate for irreversible capacity loss occurring at the cathode during initial charging and discharging, and since the decrease in electrical conductivity caused by said compound is improved, the charge / discharge capacity characteristics are excellent. In addition, since the generation of oxygen gas, etc., is suppressed during charging and discharging after the initial charging and discharging, the secondary battery containing said anode has high safety, as well as excellent cycle characteristics and lifespan characteristics.

[0062]

[0063] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described in detail in the detailed description.

[0064] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0065] In this specification, "include as a main component" may mean including a defined component in an amount of 50 wt% or more (or 50 volume% or more), 60 wt% or more (or 60 volume% or more), 70 wt% or more (or 70 volume% or more), 80 wt% or more (or 80 volume% or more), 90 wt% or more (or 90 volume% or more), or 95 wt% or more (or 95 volume% or more) with respect to the total weight (or total volume). For example, "include carbon atoms as a main component" may mean including 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, or 95 wt% or more based on the total weight of the carbon-based compound. In some cases, it may mean that the entire carbon-based compound consists of carbon atoms and is included in an amount of 100 wt%.

[0066] In addition, in this specification, "average particle size (D 50 "" can be defined as the particle size corresponding to 50% of the cumulative volume in the particle size distribution curve. The above average particle size (D 50 ) can be measured, for example, using the laser diffraction method. For example, the average particle size (D 50 ) is the average particle size (D) corresponding to 50% of the volume accumulation from the results measured by the measuring device, after dispersing the particles in a dispersion medium and introducing them into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) to irradiate with ultrasound of approximately 28 kHz at an output of 60 W. 50 ) can be calculated. The above laser diffraction method generally enables the measurement of particle sizes ranging from the submicron region to several mm, and can obtain results with high reproducibility and high resolution.

[0067]

[0068] The present invention will be described in more detail below.

[0069]

[0070] anode

[0071] The present invention is,

[0072] Positive current collector,

[0073] A first layer provided on at least one surface of the anode current collector and comprising a first anode additive and a second anode additive, and

[0074] A positive electrode is provided having a second layer provided on the first layer and comprising a positive electrode active material.

[0075]

[0076] The positive electrode according to the present invention may be applied to a lithium secondary battery. The positive electrode may have a structure in which a first layer and a second layer are sequentially arranged on a positive electrode current collector.

[0077] At this time, the first layer may function as a functional layer to improve or enhance the physical properties of the anode. For example, the first layer may be positioned between the second layer and the anode current collector to perform the function of a primer layer that increases their bonding strength. Additionally, the first layer may perform the function of compensating for lithium lost due to the negative electrode during the initial charging of the secondary battery, or the function of removing oxygen (O2) gas generated during the charging and discharging of the secondary battery after the initial charging and discharging.

[0078] The first layer may have a patterned structure to increase the bonding strength between the anode current collector and the second layer. At this time, the patterned structure is not particularly limited as long as it is a shape that can increase the surface area of ​​the first layer, but it may have a stripe pattern structure or a dot pattern structure in consideration of productivity and processability during anode manufacturing.

[0079] In addition, the first layer may include a compound as a first cathode additive in which the ratio of the activation voltage range overlapping with the operating voltage range of the cathode active material is 50% or more of the operating voltage of the cathode active material in order to compensate for lithium lost during initial charging and discharging.

[0080] Specifically, the first anode additive may include one or more compounds represented by the following chemical formula 2:

[0081] [Chemical Formula 2]

[0082] Li a M 3 (1-b) M 4 b O c

[0083] In the above chemical formula 2,

[0084] M 3 is Fe, Co, Mn, Zn, Al, or Ga, and

[0085] M 4 is at least one metal selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Co, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, wherein M 3 and M 4 It includes different metals,

[0086] a, b, and c are 1≤a≤7, 0≤b≤0.5, and 1.8≤c≤4.5.

[0087] The compound represented by the above chemical formula 2 is a superlithium compound containing an excess amount of lithium element, and can compensate for irreversible lithium loss by releasing the excess amount of lithium element during initial charging.

[0088] Compounds represented by the above chemical formula 2 include Li6CoO4 and Li6Co 0.5 Zn 0.5 O4, Li6Co 0.7 Zn 0.3 O4, Li6Co 0.7 Zn0.2 Al 0.1 O4, Li5FeO4, Li6MnO4, Li6ZnO4, Li5AlO4, Li5GaO4, etc. may be included alone or in two or more types. For example, the compound represented by Chemical Formula 2 above is M 3 This is Li6CoO4, Li6Co where Fe, Co, or Mn is Fe, Co, or Mn 0.5 Zn 0.5 O4, Li6Co 0.7 Zn 0.3 O4, Li6Co 0.7 Zn 0.2 Al 0.1 O4, Li5FeO4, Li5Fe 0.7 Mn 0.3 O4, Li5Fe 0.5 Mn 0.5 It may include at least one of O4 and Li6MnO4.

[0089] The above compounds can compensate for lithium ion loss with a small amount because they release a significantly large amount of lithium ions during the charging of the secondary battery. Furthermore, the compounds have the advantage of being easy to apply to lithium secondary batteries because the minimum potential required for the compound to release lithium—namely, the activation voltage (or decomposition voltage)—exists within the charging potential range of the lithium secondary battery. Specifically, the first cathode additive decomposes during the initial charge / discharge due to structural instability, releasing lithium ions, and the released lithium ions compensate for the lithium lost during the initial charge / discharge of the secondary battery.

[0090] At this time, the degree of lithium ion compensation may vary depending on the degree of overlap between the activation voltage, which is the minimum potential at which the first cathode additive decomposes, and the operating voltage of the cathode active material that compensates for lithium. Accordingly, the first cathode additive according to the present invention may include a compound represented by Chemical Formula 2 and have an activation voltage range that overlaps with the operating voltage range of the cathode active material by 50% or more. Specifically, the ratio of the activation voltage range of the first cathode additive overlapping with the operating voltage range of the cathode active material may be 60% or more, 70% or more, 80% or more, 50% to 95%, 50% to 90%, 60% to 85%, or 65% to 85% based on the operating voltage range of the cathode active material. If the overlap ratio between the activation voltage range of the first cathode additive and the operating voltage range of the cathode active material is lower than the lower limit described above, the decomposition of the first cathode additive does not occur sufficiently during initial charging and discharging, so there is a problem in that the charge / discharge capacity of the secondary battery is not sufficiently realized. In addition, if the above overlap ratio is higher than the upper limit described above, the side reaction caused by the first anode additive increases, so there is a limitation in that the electrochemical performance and / or safety of the secondary battery are actually reduced.

[0091] For example, when using LiFePO4 with an operating voltage range of about 3.2 to 3.6 V as the cathode active material, Li6CoO4 with an activation voltage range of about 3.7 to 4.2 V does not have a voltage range overlap, but Li5FeO4 with an activation voltage range of about 3.3 to 3.8 V can have a voltage range overlap with the operating voltage of the cathode active material by about 73 to 77%. Therefore, Li5FeO4 can be included as the first cathode additive.

[0092] The above Li5FeO4 has excellent compatibility with the cathode active material in secondary batteries that use LiFePO4, etc. as the cathode active material. Since the above Li5FeO4 has a high overlap with the operating voltage range of LiFePO4, it has the characteristic of high charge / discharge performance of the cathode after initial charge / discharge. In addition, the above Li5FeO4 has the advantage of excellent economic efficiency as it has a relatively low price compared to other lithium-ion compounds.

[0093] Meanwhile, the first anode additive has low electrical conductivity, so when applied to an anode, there is a problem in that the charge / discharge capacity of the anode is not sufficiently realized. However, the present invention is characterized by the improvement of the problem of reduced charge / discharge capacity of the anode by including the first anode additive in a first layer adjacent to the anode current collector, thereby shortening the charge transfer distance realized from the first anode additive. In addition, generally, lithium-rich compounds have low structural stability and may be damaged under high temperature and / or pressure conditions, rendering them unable to function properly. In this regard, a rolling process is performed to increase energy density during the manufacture of the anode. In this case, since the pressure stress applied to the first layer during the rolling process may be relatively less compared to the second layer, there is an advantage of significantly less damage to the first anode additive.

[0094] The first anode additive may be included in an amount ranging from 0.5 wt% to 5 wt% based on the total weight of the first layer and the second layer. For example, the first anode additive may be included in an amount ranging from 0.5 wt% to 4 wt%; 0.5 wt% to 3 wt%; 0.5 wt% to 2 wt%; 0.5 wt% to 1 wt%; 1 wt% to 5 wt%; 2.5 wt% to 5 wt%; 1 wt% to 4 wt%; 1 wt% to 3 wt%; 2 wt% to 4 wt%; 0.5 wt% to 1.3 wt%; or 0.5 wt% to 0.9 wt% based on the total weight of the first layer and the second layer. By controlling the content of the first anode additive to the above range, the present invention can prevent a decrease in charge / discharge capacity that occurs when the content of the first anode additive is low and fails to sufficiently replenish lithium ions lost due to irreversible reactions. In addition, it is possible to prevent a large amount of oxygen gas from being generated during the charging and discharging of the battery due to an excess amount of the first anode additive.

[0095] In addition, the compound represented by the above chemical formula 2 is LiFeO2, Li3FeO 3.5 and may include at least one of Li3FeO4. If the compound represented by Chemical Formula 2 is Li5FeO4, the Li5FeO4 may remain in the first layer in the form of a decomposition product remaining after releasing excess lithium ions and oxygen (O2) gas following the initial charging of the secondary battery. At this time, when the secondary battery is charged at a charging voltage in the range of 3.5V to 4.0V, the decomposition product of the Li5FeO4 may include LiFeO2 and Li3FeO 3.5 It may include etc. Additionally, the decomposition product of the above Li5FeO4 may include Li3FeO4, etc. when the secondary battery is charged at a charging voltage of 4.0V or higher. Since the above LiFeO2 has a structure capable of lithium ion intercalation and deintercalation, it can participate in electrochemical reactions in the first layer during the charging and discharging of the secondary battery. In addition, the above Li3FeO3.5 Li3FeO4, etc., possess spare lithium ions, so they can contribute to the charge / discharge capacity of the anode after initial charge / discharge / activation.

[0096] When the first anode additive comprises Li5FeO4 and LiFeO2, they may have a predetermined content ratio. Specifically, when the first anode additive comprises Li5FeO4 and LiFeO2, the LiFeO2 may be included in an amount of 10 to 500 parts by weight relative to 1 part by weight of Li5FeO4. For example, the LiFeO2 may be included in an amount of 10 to 250 parts by weight; 10 to 100 parts by weight; 10 to 50 parts by weight; 50 to 200 parts by weight; 100 to 300 parts by weight; 250 to 500 parts by weight; 50 to 100 parts by weight; 10 to 30 parts by weight; 20 to 30 parts by weight; 10 to 19 parts by weight; or 11 to 29 parts by weight relative to 1 part by weight of Li5FeO4. The present invention can prevent a rapid increase in the electrical resistance of the anode caused by a high content ratio of LiFeO2 by controlling the content ratio of Li5FeO4 and LiFeO2 included in the first anode additive to the range described above. In addition, it can prevent a decrease in the charge / discharge capacity of the anode caused by insufficient compensation for irreversible lithium loss from the cathode due to a high content ratio of Li5FeO4.

[0097] The above-mentioned first anode additive has a predetermined average particle size (D) considering the irreversible reactivity of the compound represented by Chemical Formula 2 during initial charging. 50 1st ) may have. Specifically, the first anode additive may have an average particle size (D) in the range of 0.5 μm to 20 μm. 50 1st) may have. For example, the first anode additive may have an average particle size (D) in the range of 0.5 μm to 18 μm; 0.5 μm to 15 μm; 0.5 μm to 12 μm; 0.5 μm to 10 μm; 0.5 μm to 5 μm; 0.5 μm to 3 μm; 1 μm to 9 μm; 5 μm to 20 μm; 5 μm to 15 μm; 5 μm to 13 μm; 8 μm to 19 μm; 9 μm to 15 μm; 10 μm to 20 μm; 10 μm to 15 μm; 7 μm to 14 μm; or 8 μm to 12 μm. 50 1st Can have ).

[0098] The present invention relates to the average particle size (D) of the first anode additive. 50 1st By controlling ) to the range described above, it is possible to prevent a significant amount of unreacted compound represented by Formula 2 from remaining after initial charge / discharge / activation due to an average particle size larger than the upper limit described above. The compound represented by Formula 2 remaining after initial charge / discharge / activation can act as a factor in generating gas while releasing lithium ions during the charge / discharge process. This generated gas can increase the internal pressure of the secondary battery, thereby compromising the safety of the secondary battery. Therefore, in order to allow all or most of the compound represented by Formula 2 to participate in an irreversible reaction during initial charge / discharge / activation, the average particle size (D 50 1st It is desirable to adjust ) to be below the upper limit described above. In addition, the present invention relates to an average particle size (D) smaller than the lower limit described above. 50 1st Due to this, the amount lost due to non-uniform dispersion in the first layer or scattering of the first anode additive during anode manufacturing can be minimized.

[0099] In addition, the first layer comprises a second anode additive comprising at least one of the compounds represented by the following chemical formula 1 together with the first anode additive:

[0100] [Chemical Formula 1]

[0101] M 1 x M 2 y O z

[0102] In the above chemical formula 1,

[0103] M 1 and M 2 are Li, W, Mo, Ni, Co, Nb, Ge, Ti, Ta, or Ce, respectively, where M 1 and M 2 It contains different metals,

[0104] x, y, and z are 1≤x≤3, 0≤y≤1, and 1≤z≤6, respectively.

[0105]

[0106] The first anode additive mentioned above releases an excess amount of lithium during the charging of the secondary battery, generating a significant amount of oxygen (O2) gas in the process. Furthermore, the first anode additive and / or the decomposition oxide of the first anode additive remaining in the anode active layer after the initial charge / discharge can continue to decompose and generate additional oxygen (O2) gas even when subsequent charge / discharge cycles are performed. The generated oxygen (O2) gas increases the internal pressure of the battery cell, which can deform and / or damage the battery case during the use of the secondary battery, thereby reducing the safety of the battery. Additionally, the oxygen gas can form gas traps at the interface between the anode and / or cathode, which can interfere with the electrochemical reaction of the electrodes or damage the active layer of each electrode, thereby acting as a factor that reduces the cycle characteristics and lifespan characteristics of the secondary battery. However, the present invention can overcome this by including a second anode additive in the first layer of the anode.

[0107] The second anode additive comprises one or more compounds represented by Chemical Formula 1. The compounds represented by Chemical Formula 1 include oxides containing a single metal and / or a heterogeneous metal having an oxidation number of +2 to +6. The compounds allow for the transition of metal elements due to the activation of oxidation-reduction reactions during the charging and discharging of a secondary battery under voltage conditions in the range of 2.0 to 4.0 V. In this process, the metal elements within the metal oxides may react with oxygen ions. That is, the metal elements may react with oxygen ions and be oxidized, thereby allowing oxygen (O2) generated inside the anode and / or battery to be captured and / or removed. Examples of such second anode additives include WO, WO2, WO3, MoO, MoO2, MoO3, NiO, NiO2, CoO, CoO2, NbO, NbO2, Nb2O5, GeO, GeO2, TiO, TiO2, TaO, Ta2O5, CeO2, NbTiO2, NbTiO5, NbTaO2, NbTaO5, Li2NiO2, or combinations thereof.

[0108] The size of the second anode additive is not limited, but preferably, it may have an average particle size smaller than the average particle size of the first anode additive. In this case, the second anode additive has a larger specific surface area compared to the first anode additive that generates oxygen gas, so it can effectively remove oxygen (O2) gas generated in the first layer during the charging and discharging of the secondary battery, especially during the initial charging and discharging.

[0109] Average particle size (D) of the second anode additive above 50 2nd ) is the average particle size (D) of the first anode additive 50 1st It may have a size ratio in the range of 0.5 or more and less than 1.0 based on ). For example, the average particle size (D) of the second anode additive above 50 2nd ) is the average particle size (D) of the first anode additive 50 1stBased on ), it may have a size ratio in the range of 0.6 or more and less than 1.0; 0.7 or more and less than 1.0; 0.8 or more and less than 1.0; 0.9 or more and less than 1.0; 0.5 to 0.95; 0.5 to 0.9; 0.5 to 0.75; 0.5 to 0.6; 0.7 to 0.95; 0.8 to 0.95; 0.6 to 0.8; 0.75 to 0.9; or 0.8 to 0.9. The present invention may have an average particle size (D) of the first anode additive. 50 1st Average particle size (D) of the second anode additive for ) 50 2nd By adjusting the ratio to the range described above, oxygen gas generated in the first layer due to the first anode additive can be more effectively adsorbed and removed. Specifically, if the average particle size ratio of the second anode additive exceeds the upper limit, electrons may be obtained during charging and discharging, thereby promoting the generation of oxygen (O2) gas. Additionally, if the average particle size ratio of the second anode additive is lower than the lower limit, the specific surface area of ​​the second anode additive increases, but the second anode additive is not uniformly dispersed in the first layer during anode manufacturing. In this case, there is a problem in that the efficiency of removing oxygen gas generated in the first layer as well as inside the battery is reduced.

[0110] The second anode additive may be included in a range of 5% to 25% by weight based on the total weight of the first anode additive. For example, the second anode additive may be included in a range of 5% to 20% by weight; 5% to 15% by weight; 5% to 10% by weight; 10% to 25% by weight; 15% to 25% by weight; 20% to 25% by weight; 10% to 20% by weight; 11% to 25% by weight; 13% to 24% by weight; 11% to 19% by weight; or 8% to 17% by weight based on the total weight of the first anode additive. By adjusting the content of the second anode additive to the range described above, the present invention can more effectively remove oxygen gas generated during the charging and discharging of a secondary battery without degrading the energy density and cycle characteristics of the anode.

[0111] The above-mentioned second anode additive is uniformly dispersed in the first layer together with the first anode additive, thereby effectively removing oxygen (O2) gas generated inside the anode without degrading the charge / discharge characteristics and / or life characteristics of the anode. This can be compared to the case where the first anode additive is coated with the second anode additive. Most first anode additives have very low electrical conductivity. When the second anode additive is coated on the surface of such first anode additives, the electrical conductivity of the first anode additive becomes lower, and thus there is a limitation in that the charge / discharge characteristics and / or life characteristics of the anode containing it are degraded.

[0112] The first layer may further include additional additives, such as metal compounds, organic compounds, and polymer compounds, which have a high affinity for oxygen (O2) gas, in addition to the second anode additive. Specifically, the first layer may further include a third anode additive comprising one or more of metal carbonates; metal halides; photosensitive dyes; unsaturated hydrocarbons; polymers having repeating units including amide groups; catechols; sulfites; ascorbic acid derivatives; and enzymes. The third anode additive is a compound with a high affinity for oxygen (O2) gas, and when applied together with the second anode additive, it can further maximize the efficiency of removing oxygen (O2) gas generated inside the anode.

[0113] These third anode additives may include the following compounds:

[0114] - Metal carbonates such as iron carbonate (FeCO3);

[0115] - Metal halides such as cobalt chloride (CoCl2), cobalt bromide (CoBr2), cobalt iodide (CoI2), iron chloride (FeCl2), iron bromide (FeBr2), iron iodide (FeI2), nickel chloride (NiCl2), nickel bromide (NiBr2), nickel iodide (NiI2), copper chloride (CuCl2), copper bromide (CuBr2), and copper iodide (CuI2);

[0116] - Photosensitive dyes such as quercetin, luteolin, β-carotene, lycopene, astaxanthin, heme derivatives, chlorophyll derivatives, phthalocyanine derivatives, coumarin derivatives, indigo, and indirubin;

[0117] - Carotenoids, Resveratrol, Curcumin, Tocopherol, Squalene, Fullerene (C 60 , C 70 Unsaturated hydrocarbons such as (etc.);

[0118] - Polymers having repeating units containing amide groups, such as nylon-6, nylon-66, etc.;

[0119] - Catechols such as epicatechin, epigallocatechin gallate (EGCG), dopamine, pyrogallol, and hydroquinone;

[0120] - Sulfites such as sodium sulfite (Na2SO3), sodium metasulfite (Na2S2O5), and potassium metasulfite (K2S2O5);

[0121] - Ascorbic acid derivatives such as ascorbic acid or ascorbate with sodium bicarbonate (ascorbate with NaHCO3);

[0122] - Enzymes such as glucose oxidase, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), heme globin (Hb), myoglobin (Mb), tyrosinase, lipoxygenase (LOX), etc.

[0123]

[0124] The third anode additive may be included in an amount of 1 to 25 parts by weight based on 100 parts by weight of the first anode additive. For example, the third anode additive may be included in an amount of 1 to 20 parts by weight; 1 to 15 parts by weight; 1 to 10 parts by weight; 10 to 25 parts by weight; 15 to 25 parts by weight; 20 to 25 parts by weight; 10 to 20 parts by weight; 11 to 22 parts by weight; 13 to 24 parts by weight; 11 to 19 parts by weight; 8 to 17 parts by weight; 1 to 9 parts by weight; 1 to 5 parts by weight; or 1 to 3 parts by weight based on 100 parts by weight of the first anode additive. The present invention can more effectively remove oxygen gas generated during the charging and discharging of a secondary battery without degrading the energy density and cycle characteristics of the anode by adjusting the content of the third anode additive to the range described above.

[0125] The first layer may further include a first conductive material and a first binder together with a first anode additive and a second anode additive.

[0126] The first conductive material can perform the role of compensating for the decrease in electrical conductivity caused by the first anode additive. Examples of such first conductive materials include graphite; carbon black such as acetylene black, channel black, furnace black, lamp black, and thermal black; carbon nanostructures such as carbon nanotubes and graphene; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum powder, and nickel powder; conductive whiskies such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. These may be used alone or in combination.

[0127] The first conductive material may be included in a range of 0.1 to 5 weight% based on the total weight of the first layer and the second layer. For example, the first conductive material may be included in a range of 0.1 to 4 weight%; 2 to 4 weight%; 1.5 to 5 weight%; 1 to 3 weight%; 0.1 to 2 weight%; or 0.1 to 1 weight% based on the total weight of the first layer and the second layer.

[0128] The first binder can perform the role of fixing each component included in the first layer. The first binder can be one that is adhesive and electrochemically stable.Specifically, the first binder comprises 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, polyvinylidene fluoride-co-hexafluoropropylene, and polyvinylidene Examples include 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 combinations thereof.

[0129] The first binder may be included in a range of 0.1 to 5 weight% based on the total weight of the first layer and the second layer. For example, the first binder may be included in a range of 0.1 to 4 weight%; 2 to 4 weight%; 1.5 to 5 weight%; 1 to 3 weight%; 0.1 to 2 weight%; or 0.1 to 1 weight% based on the total weight of the first layer and the second layer.

[0130] Furthermore, the first layer may further include a positive active material, similar to the second layer. In this case, the first layer can function as a positive active layer that performs an electrochemical reaction by including a positive active material together with the second layer, thus having the advantage of contributing to increasing the charge / discharge capacity and energy density of the positive.

[0131] The positive active material included in the first layer above may be the same as or different from the positive active material included in the second layer.

[0132] Specifically, the cathode active materials included in the first and second layers are materials capable of causing an electrochemical reaction and may each include a lithium iron phosphate compound represented by the following chemical formula 3, which is capable of reversibly intercalating and deintercalating lithium ions:

[0133] [Chemical Formula 3]

[0134] LiFe r M 5 (1-r) XO4

[0135] In the above chemical formula 3,

[0136] M 5 is at least one element selected from W, Cu, Fe, V, Cr, CO, Ni, Mn, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and

[0137] X is at least one element among P, Si, S, As, and Sb, and

[0138] r is 0≤r≤0.9.

[0139] The lithium iron phosphate compound represented by Chemical Formula 3 above is a promising active material that possesses excellent lifespan characteristics and superior advantages in all aspects of safety, including overcharging and over-discharging, because it has the best structural stability due to having an olivin structure. In particular, the lithium iron phosphate compound is PO4 - Due to its strong bonding strength, it has excellent high-temperature stability and is more economical than the aforementioned LiCoO2, LiNiO2, or LiMn2O4 because it contains iron, which is abundant and inexpensive, and it has low toxicity, so it has less impact on the environment.

[0140] These lithium iron phosphate compounds are phosphates containing iron (Fe) among transition metals, and in some cases, other transition metals (M 5 It may have a doped form. For example, the lithium iron phosphate compound is LiFePO4, LiFe 0.9 Mn 0.1 PO4, LiFe 0.8 Mn 0.2 PO4, LiFe 0.7 Mn 0.3 PO4, LiFe 0.5 Mn 0.5 PO4, LiFe 0.3 Mn 0.7 PO4, LiFe 0.2 Mn 0.8 PO4, LiFe 0.1 Mn 0.9 It may include PO4, etc.

[0141] Meanwhile, the second layer may further include a second conductive material, a second binder, other additives, etc., together with the positive electrode active material.

[0142] At this time, since the second conductive material and the second binder have the same composition as the first conductive material and the second binder described above, a detailed description is omitted. However, the total weight of the first conductive material and the second conductive material may be in the range of 10 weight% or less, 7.5 weight% or less, 5 weight% or less, or 0.1 to 5 weight% based on the total weight of the first layer and the second layer. More specifically, the total weight of the first conductive material and the second conductive material may be in the range of 0.1 to 4 weight%; 2 to 4 weight%; 1.5 to 5 weight%; 1 to 3 weight%; 0.1 to 2 weight%; or 0.1 to 1 weight% based on the total weight of the first layer and the second layer.

[0143] Additionally, the total weight of the first binder and the second binder may be in the range of 10% by weight or less, 7.5% by weight or less, 5% by weight or less, or 0.1% to 5% by weight based on the total weight of the first layer and the second layer. More specifically, the total weight of the first binder and the second binder may be in the range of 0.1% to 4% by weight; 2% to 4% by weight; 1.5% to 5% by weight; 1% to 3% by weight; 0.1% to 2% by weight; or 0.1% to 1% by weight based on the total weight of the first layer and the second layer.

[0144] The first and second layers above may have a specific thickness considering the electrical performance and lifespan of the anode.

[0145] Specifically, the total thickness of the first and second layers is not particularly limited, but specifically may be in the range of 50 µm to 500 µm. For example, the total thickness of the first and second layers may be in the range of 100 µm to 500 µm; 200 µm to 500 µm; 300 µm to 500 µm; 400 µm to 500 µm; 100 µm to 400 µm; 100 µm to 300 µm; 100 µm to 350 µm; 200 µm to 400 µm; 150 µm to 430 µm; 100 µm to 200 µm; 80 µm to 150 µm; 120 µm to 170 µm; 150 µm to 300 µm; 200 µm to 300 µm; or 150 µm to 190 µm.

[0146] The average thickness of the first layer may have a range of 1 µm to 30 µm. For example, the average thickness of the first layer may have a range of 1 µm to 20 µm; 1 µm to 10 µm; 5 µm to 30 µm; 10 µm to 30 µm; 15 µm to 30 µm; 20 µm to 30 µm; 5 µm to 15 µm; 15 µm to 25 µm; 8 µm to 14 µm; 1 µm to 5 µm; or 11 µm to 19 µm.

[0147] The average thickness of the first layer may have a ratio to the average thickness of the second layer in the range of 0.05 to 1.0. For example, the average thickness of the first layer may have a thickness ratio to the average thickness of the second layer in the range of 0.05 to 0.8; 0.05 to 0.6; 0.05 to 0.5; 0.05 to 0.3; 0.05 to 0.2; 0.05 to 0.15; 0.1 to 0.2; 0.1 to 0.3; 0.2 to 0.4; 0.08 to 0.14; or 0.05 to 0.11.

[0148] The average thickness of the first layer and the average thickness of the second layer can be confirmed through scanning electron microscope (SEM) analysis of the cross-section in the thickness direction of the anode, and may refer to the average value of the thickness analyzed at any three or more points confirmed through the analysis.

[0149] By controlling the average thickness conditions of the first and second layers as described above, the present invention can prevent the energy density and output performance of the anode from deteriorating due to an excessively thick first layer. In addition, it can prevent problems such as reduced adhesion between the anode current collector and the second layer due to a significantly thin first layer, or ineffective removal of oxygen gas generated during charging and discharging.

[0150] The above positive electrode may be used as a positive electrode current collector that has high conductivity without causing chemical changes in the battery. For example, the above positive electrode current collector may be a thin sheet or film containing stainless steel, aluminum, nickel, titanium, calcined carbon, etc., and in the case of containing aluminum or stainless steel, a surface-treated one containing carbon, nickel, titanium, silver, etc. may be used. In addition, the average thickness of the above current collector may be appropriately applied from 3㎛ to 500㎛, taking into consideration the conductivity and total thickness of the manufactured positive electrode.

[0151]

[0152] The anode according to the present invention has the above-described configuration, thereby providing an effect of improving safety issues caused by oxygen gas generated during charging and discharging. In addition, the anode has the advantage of excellent cycle characteristics and lifespan characteristics.

[0153]

[0154] Method for manufacturing an anode

[0155] The present invention is,

[0156] Step (S1) of applying a first slurry comprising a first anode additive and a second anode additive to at least one surface of an anode current collector,

[0157] A step (S2) of applying a second slurry containing an anode active material onto a first slurry applied, and

[0158] A method for manufacturing an anode is provided, comprising the step (S3) of drying the applied first slurry and second slurry.

[0159]

[0160] The method for manufacturing an anode according to the present invention refers to the method for manufacturing an anode of the present invention described above.

[0161] A method for manufacturing an anode according to the present invention comprises the steps of: applying a first slurry containing a first anode additive and a second anode additive to at least one surface of an anode current collector (S1); applying a second slurry containing an anode active material onto the applied first slurry (S2); and drying the applied first slurry and the second slurry (S3).

[0162] At this time, steps (S1) and (S2) refer to a process of coating the surface of a moving positive current collector by simultaneously or continuously discharging a first slurry containing a first positive additive and a second positive additive and a second slurry containing a positive active material. Accordingly, the first slurry is applied to at least one surface of the positive current collector, and the second slurry is applied on the applied first slurry.

[0163] The above steps (S1) and (S2) may be applied without particular limitation as long as they are methods commonly applied in the industry, but preferably, a die coating method may be used. The die coating method may be performed through a slot die equipped with a shim for controlling the discharge conditions of the slurry. In this case, by controlling the shape, position, etc. of the shim, the loading amount and coating thickness of the slurry applied on the anode current collector can be easily controlled.

[0164] For example, the present invention can simultaneously apply a first slurry and a second slurry onto an anode current collector using a dual die. In this case, there is an advantage of significantly increasing process efficiency compared to applying each slurry sequentially.

[0165] The above step (S1) may be performed under specific conditions. The first anode additive included in the first slurry has low structural stability and may easily decompose under high temperature conditions or under water (H2O) and / or oxygen gas conditions. If the first anode additive decomposed in this way is included in the first layer of the anode, the effect of compensating for irreversibly lost lithium during the initial charge / discharge / activation of the secondary battery may be significantly reduced. Accordingly, the present invention may perform the application of the first slurry containing the first anode additive under specific conditions.

[0166] Specifically, the above step (S1) may be performed under an atmosphere in which one or more of the temperature conditions, humidity conditions, and gas conditions are present.

[0167] The above step (S1) may be performed at a temperature in the range of 30°C or lower. For example, the above step (S1) may be performed at a temperature in the range of 10°C to 30°C; 15°C to 30°C; 20°C to 30°C; 10°C to 25°C; 10°C to 20°C; 15°C to 25°C; 15°C to 22°C; 15°C to 20°C; or 11°C to 21°C.

[0168] The above step (S1) may be performed under relative humidity (RH) conditions in the range of 10% or less. For example, the above step (S1) may be performed under relative humidity (RH) conditions in the range of 0% to 10%; 0% to 8%; 0% to 6%; 0% to 5%; 0% to 4%; 0% to 3%; 0% to 1%; 0.001% to 0.9%; 1% to 9%; 2% to 8%; 4% to 5%; 0.001% to 0.1%; or 0.001% to 0.01%. Here, the relative humidity is (current water vapor amount / saturated water vapor amount) X 100, and can be calculated from the ratio of the measured internal humidity to the saturated water vapor amount based on the internal temperature of the reactor to which the first slurry is applied.

[0169] The above step (S1) may be performed under oxygen partial pressure conditions in the range of 5% or less. For example, the above step (S1) may be performed under oxygen partial pressure conditions in the range of 0% to 5%; 0% to 4%; 0% to 3%; 0% to 2%; 0% to 1%; 0.1% to 5%; 0.5% to 5%; 1% to 5%; 2.5% to 5%; 0.1% to 2%; 0.1% to 1%; 0.5% to 1%; or 0.01% to 0.9%.

[0170] The present invention can minimize structural damage to the first anode additive contained in the first slurry when the first slurry is applied due to conditions exceeding the upper limit of the range by adjusting the temperature condition, relative humidity condition, and / or oxygen partial pressure condition to the range described above. Additionally, it can prevent an increase in the cost of performing the step (S1) due to conditions lower than the lower limit of the range.

[0171] Meanwhile, since the first slurry and the second slurry have the same composition as the first and second layers of the anode described above, a detailed description is omitted.

[0172] The solid content of the first slurry can be controlled depending on whether a positive electrode active material is added. Specifically, the first slurry may have a solid content in the range of 1 to 20% when it includes a first positive electrode additive, a second positive electrode additive, a conductive material, and a binder. For example, the first slurry may have a solid content in the range of 1 to 15%, 1 to 10%, 1 to 9%, 5 to 15%, 5 to 10%, or 3 to 9% when it includes a first positive electrode additive, a second positive electrode additive, a conductive material, and a binder.

[0173] In addition, the first slurry may have a solid content in the range of 20 to 70% when it includes a positive electrode active material, a first positive electrode additive, a second positive electrode additive, a conductive material, and a binder. For example, the first slurry may have a solid content in the range of 25 to 70%, 30 to 70%, 40 to 70%, 45 to 70%, 50 to 70%, 25 to 60%, 25 to 50%, 25 to 40%, 30 to 60%, or 45 to 60% when it includes a positive electrode active material, a first positive electrode additive, a second positive electrode additive, a conductive material, and a binder.

[0174] The present invention allows not only to uniformly apply the first slurry by adjusting the solid content of the first slurry to the range described above depending on whether or not the positive electrode active material is included, but also to easily control the loading amount and / or thickness of the first slurry being applied.

[0175] The method for manufacturing an anode according to the present invention includes a step (S3) of drying the first slurry and the second slurry applied after the above step (S2) to form a first layer and a second layer on an anode current collector.

[0176] At this time, the above drying can be applied without particular limitation as long as it is a method that can be conventionally applied in the industry. For example, the above drying can be performed by applying thermal energy to the coated slurry using a hot air dryer, a vacuum oven, etc., to dry each slurry.

[0177] Additionally, the method may further include a step (S4) of rolling the first layer and the second layer formed by drying after the above step (S3). The rolling refers to a process of increasing the density of the entire layer by applying pressure to the surface of the first layer and the second layer formed using a roll press, etc.

[0178] At this time, the above rolling can be performed using rolling equipment such as a roll press, under linear pressure conditions applied up to the target thickness and target porosity, and then vacuum dried to manufacture an anode having a first layer and a second layer formed on an anode current collector.

[0179] For example, the above rolling can be performed under conditions where the target thickness (i.e., the average thickness of the first and second layers) is 100 μm to 400 μm and the target porosity (i.e., the porosity after rolling) is 21% to 30%.

[0180] Specifically, the rolling may be performed at a temperature in the range of 20°C to 100°C, more specifically at a temperature in the range of 20°C to 80°C; 20°C to 60°C; 20°C to 40°C; 20°C to 30°C; 30°C to 100°C; 40°C to 100°C; 60°C to 100°C; 75°C to 100°C; 85°C to 100°C; 50°C to 90°C; 60°C to 80°C; or 65°C to 90°C.

[0181] In addition, the above rolling may be performed at a rolling speed in the range of 2 m / s to 7 m / s, and more specifically, at a rolling speed in the range of 2 m / s to 6.5 m / s; 2 m / s to 6 m / s; 2 m / s to 5.5 m / s; 2 m / s to 5 m / s; 2 m / s to 4.5 m / s; 2 m / s to 4 m / s; 2.5 m / s to 4 m / s; 2.5 m / s to 3.5 m / s; 3.5 m / s to 5 m / s; 5 m / s to 7 m / s; 5.5 m / s to 6.5 m / s or 6 m / s to 7 m / s.

[0182] In addition, the above rolling can be performed under pressure conditions ranging from 50 MPa to 200 MPa, and specifically, under pressure conditions ranging from 50 MPa to 150 MPa; 50 MPa to 100 MPa; 100 MPa to 200 MPa; 150 MPa to 200 MPa; or 80 MPa to 140 MPa.

[0183] In addition, the above vacuum drying conditions can be performed for 1 to 15 hours at, for example, 100°C to 250°C, specifically 160°C to 200°C.

[0184] The present invention can maximize the energy density of the first layer and the second layer while minimizing structural damage to the first anode additive contained in the first layer by performing rolling under the above temperature, speed, and / or pressure conditions.

[0185]

[0186] lithium secondary battery

[0187] Furthermore, the present invention,

[0188] An electrode assembly comprising an anode, a cathode, and a separator disposed between the anode and the cathode according to the present invention as described above; and

[0189] A secondary battery comprising an electrolyte composition that impregnates the electrode assembly is provided.

[0190]

[0191] The secondary battery according to the present invention may be a lithium secondary battery. The lithium secondary battery includes the positive electrode of the present invention described above in an electrode assembly, exhibiting excellent safety and superior cycle and life characteristics.

[0192] In this case, the electrode assembly has a structure comprising a positive electrode, a negative electrode, and a separator positioned between the positive and negative electrodes to insulate them, and may have a stacked, stacked, or jelly-roll wound form. Since an electrode assembly of this type exhibits high energy density within a limited space, it offers the advantage of high utility in terms of energy density or output of a secondary battery.

[0193] The electrode assembly may be structured to be embedded in a state connected to each lead of the positive and negative electrodes formed outside the pouch case. Specifically, the positive lead and the negative lead may be formed to extend from the inside to the outside of the pouch case. In this case, the positive lead and the negative lead may be structured to be drawn out to the outside of the pouch case, extending in the same direction or in opposite directions.

[0194] Meanwhile, since the anode provided in the above electrode assembly has the same configuration as previously described, a detailed description is omitted.

[0195] In addition, the above cathode, like the anode, includes a cathode active layer comprising a cathode active material on at least one surface of the cathode current collector.

[0196] At this time, as the negative electrode active material, a material capable of reversibly intercalating / deintercalating lithium ions can be used.

[0197] Examples of materials capable of reversibly intercalating / deintercalating the above lithium ions include carbon materials, namely carbon-based negative electrode active materials commonly used in lithium secondary batteries. The above carbon-based negative electrode active material refers to a material having carbon atoms as its main component, and such carbon-based negative electrode active materials may include graphite-based compounds. For example, the above carbon-based negative electrode active material may include natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, carbon microbeads, as well as mesophase calcined carbon (bulk mesophase, liquid crystal pitch-based carbon fiber, etc.) made from tar and pitch as raw materials, or cokes (raw coke, green coke, pitch coke, needle coke, petroleum coke, coal coke, etc.) that have been graphitized.

[0198] The above carbon-based negative electrode active material may have the form of an assembly in which a plurality of particles are assembled. In this case, one graphite assembly may be formed by assembling 2 to 100 graphite particles, preferably 3 to 20.

[0199] The above-mentioned negative electrode active material may further include a silicon-based negative electrode active material. The silicon-based negative electrode active material is a material containing silicon (Si) as a main component, which can increase the charge / discharge capacity and energy density per unit volume of the negative electrode. Examples of such silicon-based negative electrode active materials include silicon (Si), silicon carbide (SiC), silicon monoxide (SiO), or silicon dioxide (SiO2), and these may be included alone or used in combination in the negative electrode active layer. When silicon monoxide (SiO) and silicon dioxide (SiO2) are uniformly mixed or composited and included in the negative electrode active layer as the silicon-based negative electrode active materials, they are silicon oxide (SiO2 q , provided that 0.5≤q≤2.5) can be expressed as.

[0200] In addition, the silicon-based negative electrode active material may be doped with or alloyed with C, Li, Mg, Al, Ca and / or Ti, etc. In addition, when the silicon-based negative electrode active material contains oxygen (O), the surface may be treated with a carbon coating layer or the like to suppress volume expansion during charging and simultaneously improve the electrical conductivity of the negative electrode active material.

[0201] In addition, the silicon-based negative electrode active material may be included in an amount of 0.1 to 30 weight% with respect to the total weight of the second negative electrode active layer. Specifically, the silicon-based negative electrode active material may be included in an amount of 0.1 to 25 weight%, 20 to 30 weight%, 10 to 30 weight%, 0.5 to 20 weight%, 1 to 9 weight%, 5 to 15 weight%, 3 to 7 weight%, 11 to 19 weight%, 13 to 17 weight%, 15 to 20 weight%, 3 to 13 weight%, or 1 to 15 weight% with respect to the total weight of the second negative electrode active layer. By adjusting the content ratio of the silicon-based negative electrode active material to the above range, the present invention can improve the charge capacity per unit mass while reducing lithium consumption and irreversible capacity loss during the initial charge and discharge of the secondary battery. In addition, by minimizing the volume change of the negative electrode active layer during charging and discharging of the secondary battery, the structural stability of the negative electrode active layer can be improved, thereby extending the lifespan of the secondary battery.

[0202] In addition, the above-mentioned cathode active layer may optionally include a conductive material, a binder, other additives, etc., along with the cathode active material which is the main component, as needed.

[0203] The above conductive material may include one or more types such as carbon black, acetylene black, ketjen black, carbon nanotubes, carbon fibers, etc., but is not limited thereto.

[0204] For example, the above-mentioned cathode active layer may contain carbon black, carbon nanotubes, carbon fibers, etc., as a conductive material, either alone or in combination.

[0205] At this time, the content of the conductive material may be 0.1 to 10 parts by weight per 100 parts by weight of the entire cathode active layer. Specifically, the conductive material may be 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, 2 to 6 parts by weight, or 0.5 to 2 parts by weight. By controlling the content of the conductive material within the above range, the present invention can prevent the decrease in charging capacity caused by an increase in the resistance of the cathode due to a low content of the conductive material. Furthermore, the present invention can prevent problems such as a decrease in charging capacity due to a decrease in the content of the cathode active material caused by an excessive amount of conductive material exceeding the above range, or an increase in electrical resistance due to an increase in the loading amount of the cathode active layer.

[0206] In addition, the binder is a component that assists in the bonding of the cathode active material and the conductive material, and the bonding to the current collector, and can be appropriately applied within a range that does not degrade the electrical properties of the cathode. For example, the binder may include one or more of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride (PVdF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene butadiene rubber (SBR), and fluororubber.

[0207] The content of the binder may be 0.1 to 10 parts by weight per 100 parts by weight of the entire cathode active layer. Specifically, the binder may be 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, or 2 to 6 parts by weight. By controlling the content of the binder contained in the cathode active layer to the above range, the present invention can prevent the adhesion of the active layer from being reduced due to a low content of binder or the electrical properties of the cathode from being reduced due to an excessive amount of binder.

[0208] In addition, the above-mentioned negative electrode may be used as a negative current collector that has high conductivity without causing chemical changes in the battery. For example, the above-mentioned positive current collector may be a thin sheet or film containing stainless steel, aluminum, nickel, titanium, calcined carbon, etc., and in the case of containing aluminum or stainless steel, a surface-treated one containing carbon, nickel, titanium, silver, etc. may be used. Furthermore, the average thickness of the above-mentioned current collector may be appropriately applied from 3㎛ to 500㎛, taking into consideration the conductivity and total thickness of the manufactured positive electrode.

[0209] The separator interposed between the positive and negative electrodes of the above-described lithium secondary battery is an insulating thin film having high ion permeability and mechanical strength, and is not particularly limited as long as it is one commonly used in the industry. Specifically, the separator may be one comprising one or more polymers selected from chemically resistant and hydrophobic polypropylene; polyethylene; and polyethylene-propylene copolymer. The separator may have the form of a porous polymer substrate, such as a sheet or nonwoven fabric, containing the aforementioned polymer, and in some cases, may have the form of a composite separator in which organic or inorganic particles are coated on the porous polymer substrate by an organic binder. In addition, the separator may have an average pore diameter of 0.01 μm to 10 μm and an average thickness of 5 μm to 300 μm.

[0210] Furthermore, the above electrolyte composition may include a non-aqueous organic solvent, a lithium salt, and an electrolyte additive.

[0211] The above-mentioned non-aqueous organic solvent can be applied without particular limitation as long as it is used in the industry for non-aqueous electrolytes. For example, the above-mentioned non-aqueous organic solvents include N-methyl-2-pyrrolidinone, ethylene carbonate (EC), propylene carbonate (PC), propylene carbonate, butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), gamma-butyrolactone, 1,2-dimethoxyethane (DME), tetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, ether, methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), etc. Aprotic organic solvents can be used.

[0212] In addition, the non-aqueous organic solvent used in the present invention may be used as a single type, or two or more types may be mixed in any combination or ratio according to the application. Among these, it is particularly desirable to mix propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, etc., from the perspective of electrochemical stability against oxidation and reduction and chemical stability against heat or reaction with solutes.

[0213] The above lithium salts may be applied without particular limitation as long as they are used in the industry for non-aqueous electrolytes. Specifically, the above lithium salts include LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10It may include one or more of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi and (FSO2)2NLi.

[0214] The lower limit of the appropriate concentration range for using the above lithium salt is 0.5 mol / L or higher, specifically 0.7 mol / L or higher, more specifically 0.9 mol / L or higher, and the upper limit is 2.5 mol / L or lower, specifically 2.0 mol / L or lower, more specifically 1.5 mol / L or lower. If the concentration of the lithium salt is lower than 0.5 mol / L, the ion conductivity decreases, which may lead to a decrease in the cycle characteristics and output characteristics of the non-aqueous electrolyte battery. In addition, if the concentration of the lithium salt exceeds 2.5 mol / L, the viscosity of the electrolyte for the non-aqueous electrolyte battery increases, which may also lead to a decrease in ion conductivity and a decrease in the cycle characteristics and output characteristics of the non-aqueous electrolyte battery.

[0215] In addition, when a large amount of lithium salt is dissolved in a non-aqueous organic solvent at once, the temperature of the electrolyte composition may rise due to the heat of dissolution of the lithium salt. If the temperature of the non-aqueous organic solvent rises significantly due to the heat of dissolution of the lithium salt in this way, in the case of a lithium salt containing fluorine, decomposition is accelerated, and there is a risk that hydrogen fluoride (HF) will be generated. Hydrogen fluoride (HF) is undesirable because it causes degradation of battery performance. Therefore, the temperature at which the lithium salt is dissolved in the non-aqueous organic solvent is not particularly limited, but can be controlled to -20 to 80°C, and specifically to 0 to 60°C.

[0216] Furthermore, the above electrolyte additive may be included as an additional auxiliary component to improve the physical properties of the electrolyte composition. Electrolyte additives generally used in the non-aqueous electrolyte of the present invention may be added in any proportion. Specifically, examples include compounds having an overcharge prevention effect, a negative electrode film formation effect, and a positive electrode protection effect, such as cyclohexylbenzene, biphenyl, t-butylbenzene, carbonate, vinylethylene carbonate, difluoroanisole, fluoroethylene carbonate, propanesulfone, succinonitrile, and dimethylvinylene carbonate. In addition, it is also possible to use an electrolyte for a non-aqueous electrolyte battery by solidifying it with a gelling agent or a crosslinking polymer, as in the case of use in a non-aqueous electrolyte battery called a lithium polymer battery.

[0217] For example, the above electrolyte additive may include a compound represented by the following chemical formula 4 to suppress the generation of oxygen gas inside the secondary battery during charging and discharging or to remove the generated oxygen gas:

[0218] [Chemical Formula 4]

[0219]

[0220] In the above chemical formula 4,

[0221] R1 to R6 are each hydrogen, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, wherein at least one of R1 to R6 is -L1-(CH) n It is -R7, and,

[0222] The above L1 is a direct bond, -O- or -COO-, and

[0223] The above R7 is an aliphatic unsaturated hydrocarbon group having 2 to 6 carbon atoms, and

[0224] The above n is an integer from 1 to 6.

[0225]

[0226] Specifically, in the above chemical formula 4,

[0227] R1 to R6 are each hydrogen, methyl group, ethyl group, propyl group, butyl group, methoxy group, ethoxy group, or propoxy group, wherein at least one of R1 to R6 is -L1-(CH) n It is -R7, and,

[0228] The above L1 is a direct bond, -O- or -COO-, and

[0229] The above R7 is an alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms, and

[0230] The above n is an integer from 1 to 3.

[0231]

[0232] More specifically, in the above chemical formula 4,

[0233] R1 to R6 are each hydrogen, a methyl group, an ethyl group, a methoxy group, or an ethoxy group, wherein at least one of R1 to R6 is -L1-(CH) n It is -R7, and,

[0234] The above L1 is a direct bond, -O- or -COO-, and

[0235] The above R7 is an ethenyl group or an ethylnyl group, and

[0236] The above n is 1 or 2.

[0237]

[0238] The compound represented by Chemical Formula 4 above has a structure in which an aliphatic unsaturated hydrocarbon group is introduced around a coumarin group serving as the core. The hydrocarbon group with a double-ring structure included in the coumarin group includes an ester group introduced within the ring, and thus has a higher affinity for oxygen than the non-aqueous organic solvent of the electrolyte composition. Therefore, the compound represented by Chemical Formula 4 can rapidly react with and remove oxygen gas present in the secondary battery. Furthermore, the aliphatic unsaturated hydrocarbon group introduced into the coumarin group can achieve the effect of suppressing the generation of oxygen gas inside the battery during charging and discharging by participating in the formation of an organic-inorganic film on the surface of the positive and / or negative electrode.

[0239] Examples of compounds represented by such Chemical Formula 4 include compounds represented by the following <Structural Formula 1> to <Structural Formula 11>:

[0240] <Structural Formula 1>

[0241]

[0242] <Structural Formula 2>

[0243]

[0244] <Structural Formula 3>

[0245]

[0246] <Structural Formula 4>

[0247]

[0248] <Structural Formula 5>

[0249]

[0250] <Structural Formula 6>

[0251]

[0252] <Structural Formula 7>

[0253]

[0254] <Structural Formula 8>

[0255]

[0256] <Structural Formula 9>

[0257]

[0258] <Structural Formula 10>

[0259]

[0260] <Structural Formula 11>

[0261]

[0262] The compounds represented by the above <Structural Formula 1> to <Structural Formula 11> have excellent reactivity to oxygen elements and can have the characteristic of high efficiency in removing oxygen gas present inside the secondary battery. In addition, the compounds participate in the formation of organic and inorganic films on the surface of the positive and / or negative electrodes, and thus have a high effect of suppressing side reactions between the electrode and the electrolyte composition, so they have an excellent effect in suppressing the generation of oxygen gas during charging and discharging.

[0263] When the anode additive is a compound represented by Chemical Formula 4, the anode additive may be included in a range of 0.01% to 5% by weight based on the total weight of the electrolyte composition. For example, if the anode additive is a compound represented by Chemical Formula 4, the anode additive may be included in an amount of 0.01 wt% to 4 wt%, 0.02 wt% to 4.5 wt%, 0.05 wt% to 4 wt%, 0.07 wt% to 3.7 wt%, 0.1 wt% to 3.5 wt%, 0.15 wt% to 3.3 wt%, 0.2 wt% to 3 wt%, 0.3 wt% to 2.7 wt%, 0.4 wt% to 2.5 wt%, 0.5 wt% to 2.2 wt%, 0.6 wt% to 2 wt%, 0.7 wt% to 1.8 wt%, 0.8 wt% to 1.5 wt%, or a range between any two of these values, based on the total weight of the electrolyte composition.

[0264] If the content of the above electrolyte additive is lower than the lower limit of the above range, the effect of removing oxygen gas may be negligible. Furthermore, if the content of the above electrolyte additive is higher than the upper limit of the above range, the resistance of the electrolyte composition increases significantly, leading to problems such as deterioration in the cycle characteristics and lifespan characteristics of the secondary battery.

[0265]

[0266] The present invention will be explained in more detail below through examples and comparative examples.

[0267] However, the following examples and comparative examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and comparative examples.

[0268]

[0269] Examples 1–10 and Comparative Examples 1–2. Preparation of anodes

[0270] LiFePO4(D as a positive electrode active material 50 : approximately 1㎛) is prepared, and Li5FeO4(D 50 1st : approximately 1㎛) was prepared. In addition, WO3, Li2NiO2, and TiO2 were prepared as the second anode additives, respectively, and carbon black (D) was prepared as the conductive material. 50 : (about 3~5㎛) and polyvinylidene fluoride (PVdF) as a binder were prepared.

[0271] Once preparation was complete, a first slurry (solid content: 45%) for forming the first layer was prepared by mixing the first cathode additive, the second cathode additive, the cathode active material, the conductive material, and the binder in N-methylpyrrolidone (NMP) such that the content ratios shown in Table 1 below were based on the total weight of the first and second layers provided on the cathode. At this time, ① the average particle size (D of the second cathode additive) 50 ) and ② the type of second anode additive was adjusted as shown in Table 1 below.

[0272] Separately, a second slurry (solid content: 50%) for forming a second layer was prepared by mixing a cathode active material, a conductive material, and a binder, respectively, with N-methylpyrrolidone (NMP) so that the content ratios are as shown in Table 2 below, based on the total weight of the first layer and the second layer provided on the cathode.

[0273] An anode was manufactured by sequentially applying a prepared first slurry and a second slurry onto an aluminum foil (average thickness: 10 μm) and then dry-rolling. At this time, the first slurry was applied under conditions of 20 ± 2°C, relative humidity (RH) of 5% or less, and an oxygen partial pressure of 0.1 to 1.0%. In addition, the average thickness (T) of the first layer of the manufactured anode 1st ) and the ratio of the average thickness of the first layer to the second layer (T 1st / T 2nd ) was adjusted as shown in Table 2 below.

[0274] Content Unit: Weight % 1st Slurry Composition Content of Cathode Active Material Content of 1st Cathode Additive 2nd Cathode Additive Conductor Content Binder Content Type D 50 Content Example 10 2.5 Li2NiO 20.6 µm 0.4 1.5 1.0 Example 24.7 2.5 WO 30.6 µm 0.4 1.5 1.0 Example 34.7 2.5 TiO 20.6 µm 0.4 1.5 1.0 Example 44.7 2.5 Li2NiO 20.6 µm 0.4 1.5 1.0 Example 54.7 2.5 Li2NiO 20.3 µm 0.4 1.5 1.0 Example 64.9 2.5 Li2NiO 20.6 µm 0.1 1.5 1.0 Example 74.5 2.5 Li2NiO 20.6 µm 0.8 1.5 1.0 Example 84.7 2.5 Li2NiO 20.6 µm 0.4 1.5 1.0 94.7 2.5 Li2NiO2 0.6 µm 0.4 1.5 1.0 Example 10 4.7 2.5 Li2NiO2 0.6 µm 0.4 1.5 1.0 Comparative Example 14.7 2.5 0 1.5 1.0 Comparative Example 24.7 2.5 Li2NiO2 1 µm 0.4 1.5 1.0

[0275] Content Unit: Weight % Component Content T of the Second Slurry 1st [㎛]T 1st / T 2ndCathode active material conductive agent binder Example 193.11.00.5150.08 Example 288.41.00.5150.08 Example 388.41.00.5150.08 Example 488.41.00.5150.08 Example 588.41.00.5150.08 Example 688.51.00.5150.08 Example 788.21.00.5150.08 Example 888.41.00.510.006 Example 988.41.00.5350.194 Example 1088.41.00.52001.11 Comparative Example 188.81.00.5150.08 Comparative Example 288.41.00.5150.08

[0276]

[0277]

[0278] Examples 11–20 and Comparative Examples 3–4. Preparation of secondary batteries

[0279] A cathode containing a cathode active layer was prepared by applying a cathode slurry containing 97 wt% artificial graphite as a carbon-based cathode active material and 3 wt% carboxymethylcellulose (CMC) and styrene butadiene rubber (SBR) mixed in a 1:1 weight ratio as a binder onto a copper foil (average thickness: 12 μm) and then dry rolling.

[0280] An electrode assembly was fabricated by alternately arranging nine positive electrodes and ten negative electrodes prepared in the previous examples or comparative examples, with an 18 μm polyethylene porous separator interposed between them. The fabricated electrode assembly was inserted into a battery case, and an electrolyte composition was injected to manufacture a small pouch-type lithium secondary battery.

[0281] Here, the electrolyte composition used was an organic solvent in which ethylene carbonate (EC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) were mixed in a volume ratio of 3:4:3 and LiPF6 was dissolved to a concentration of 1M.

[0282] Type of anode used Example 11 Anode prepared in Example 1 Example 12 Anode prepared in Example 2 Example 13 Anode prepared in Example 3 Example 14 Anode prepared in Example 4 Example 15 Anode prepared in Example 5 Example 16 Anode prepared in Example 6 Example 17 Anode prepared in Example 7 Example 18 Anode prepared in Example 8 Example 19 Anode prepared in Example 9 Example 20 Anode prepared in Example 10 Comparative Example 3 Anode prepared in Comparative Example 1 Comparative Example 4 Anode prepared in Comparative Example 2

[0283]

[0284]

[0285] Examples 21 and 22. Preparation of secondary batteries

[0286] A small pouch-type lithium secondary battery was manufactured by performing the same method as in Example 14, except that 0.1% by weight of an electrolyte additive represented by the following <Structural Formula 1> or <Structural Formula 10> was added based on the total weight of the electrolyte composition.

[0287] <Structural Formula 1>

[0288]

[0289] <Structural Formula 10>

[0290] .

[0291]

[0292]

[0293] Experimental Example.

[0294] To evaluate the performance of the anode according to the present invention and a secondary battery containing the same, the following experiment was performed.

[0295]

[0296] Oxygen removal capacity

[0297] The thickness of each lithium secondary battery prepared in the examples and comparative examples was measured for the first time. Subsequently, each lithium secondary battery was pre-aged at room temperature (22±2℃) for 2 days and then activated by charging at 0.1C until the state of charge (SOC) reached 30%. Afterward, each activated lithium secondary battery was aged at room temperature (22±2℃) and 60℃ for 1 day each, and the thickness of each lithium secondary battery was measured for the second time. The rate of change in the thickness measured for the second time was calculated based on the thickness of the secondary battery measured for the first time. It was determined that the lower the calculated rate of change in thickness, the higher the removal rate of gas generated during activation.

[0298] In addition, a total of 300 charge-discharge cycles were performed on each activated lithium secondary battery, and the thickness of each lithium secondary battery was measured three times. At this time, the charge-discharge cycle was set as one cycle by charging at 45±2℃ under constant current / constant voltage conditions of 2.0C, 3.65V, and 0.05C cut-off, and discharging under constant current conditions of 0.5C and 2.5V cut-off.

[0299] The rate of change in thickness of the secondary battery measured in the third measurement was calculated based on the thickness of the secondary battery measured in the first measurement. It was determined that the smaller the calculated rate of change in thickness, the higher the removal rate of gas generated during charging and discharging after activation. The calculated results are shown in Table 4 below.

[0300]

[0301] Cycle characteristics

[0302] Each lithium secondary battery prepared in the examples and comparative examples was activated by charging to 4.2V at a rate of 0.3C at 25℃ under CC-CV conditions and discharging to 2.5V at a rate of 0.3C under CC conditions.

[0303] One cycle was defined as charging each activated lithium secondary battery to 4.2V at a rate of 1.0C under CC-CV conditions at a temperature of 25°C and discharging to 2.5V at a rate of 1.0C under CC conditions, and one cycle of charge-discharge was performed on each lithium secondary battery prepared in the examples and comparative examples. At this time, the capacity was measured during charge-discharge to confirm the charge-discharge capacity of the first cycle. Subsequently, charge-discharge was performed on each lithium secondary battery 499 times for a total of 500 cycles. At this time, the charge-discharge capacity of the 500th cycle was confirmed during the final cycle. The charge-discharge capacity retention rate of the 500th cycle was calculated based on the measured charge-discharge capacity of the first cycle. The results are shown in Table 4 below.

[0304] Change in thickness of secondary battery Capacity retention rate Immediately after activation Immediately after 300 charge / discharge cycles Example 1 11 10% 131% 81% Example 12 109% 128% 87% Example 13 108% 128% 85% Example 14 108% 130% 86% Example 15 115% 150% 70% Example 16 121% 180% 65% Example 17 110% 130% 79% Example 18 145% 235% 78% Example 19 120% 140% 74% Example 20 107% 130% 72% Example 21 105% 123% 88% Example 22 106% 125% 86% Comparative Example 3 175% 295% 59% Comparative Example 4170%260%63%

[0305]

[0306]

[0307] As shown in Table 4 above, it can be seen that the anode manufactured in the example has an excellent effect in removing oxygen gas generated during the activation of the secondary battery and subsequent charging and discharging.

[0308] In addition, the anode was found to have an excellent charge / discharge capacity retention rate after 500 cycles by including a first anode additive and a second anode additive in a first layer adjacent to the anode current collector.

[0309] From these results, it can be seen that the anode according to the present invention includes a lithium-over-compound as a first anode additive, so that lithium lost from the cathode upon activation is compensated, and oxygen gas generated at that time is effectively removed. In addition, it can be seen that the anode has good electrical conductivity and excellent cycle characteristics and lifespan characteristics.

[0310]

[0311] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art or those with ordinary knowledge in the art will understand that various modifications and changes can be made to the invention without departing from the technical features of the invention as described in the claims set forth below.

[0312] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

Claims

1. Positive current collector, A first layer provided on at least one surface of the anode current collector and comprising a first anode additive and a second anode additive, and It includes a second layer provided on the first layer and comprising a positive electrode active material; The first anode additive comprises a compound in which the ratio of the activation voltage range overlapping with the operating voltage range of the anode active material is 50% or more based on the operating voltage of the anode active material; The second anode additive comprises one or more compounds represented by the following chemical formula 1; An anode characterized in that the average particle size of the second anode additive is smaller than the average particle size of the first anode additive: [Chemical Formula 1] M 1 x M 2 y O z In the above chemical formula 1, M 1 and M 2 are Li, W, Mo, Ni, Co, Nb, Ge, Ti, Ta, or Ce, respectively, where M 1 and M 2 It contains different metals, x, y, and z are 1≤x≤3, 0≤y≤1, and 1≤z≤6, respectively.

2. In Paragraph 1, Average particle size (D) of the first anode additive above 50 ) is an anode in the range of 0.5㎛ to 20㎛.

3. In Paragraph 1, An anode having an average particle size of the second anode additive having a ratio of 0.5 or more and less than 1.0 based on the average particle size of the first anode additive.

4. In Paragraph 1, The above-mentioned first anode additive is an anode comprising one or more of the compounds represented by the following chemical formula 2: [Chemical Formula 2] Li a M 3 (1-b) M 4 b O c In the above chemical formula 2, M 3 is Fe, Co, Mn, Zn, Al, or Ga, and M 4 is at least one metal selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Co, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, wherein M 3 and M 4 It includes different metals, a, b, and c are 1≤a≤7, 0≤b≤0.5, and 1.8≤c≤4.5, respectively.

5. In Paragraph 1, An anode in which the content of the first anode additive is in the range of 0.5% to 5% by weight based on the total weight of the first layer and the second layer.

6. In Paragraph 1, The above-mentioned second anode additive is included in a range of 5% to 25% by weight based on the total weight of the first anode additive.

7. In Paragraph 1, The first layer further comprises a third anode additive comprising one or more of metal carbonates; metal halides; photosensitive dyes; unsaturated hydrocarbons; polymers having repeating units including amide groups; catechols; sulfites; ascorbic acid derivatives; and enzymes, and The above metal carbonate or metal chloride is an anode comprising at least one metal selected from iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu).

8. In Paragraph 7, The above third anode additive is an anode included in an amount of 1 to 25 parts by weight based on 100 parts by weight of the first anode additive.

9. In Paragraph 1, An anode having an average thickness of the first layer in the range of 1㎛ to 30㎛.

10. In Paragraph 1, An anode in which the average thickness of the first layer is in the range of 0.05 to 1 as a ratio to the average thickness of the second layer.

11. In Paragraph 1, The above first layer is a positive electrode further comprising a positive electrode active material.

12. In Paragraph 11, The positive electrode active material included in the first and second layers above comprises a positive electrode comprising a lithium iron phosphate compound represented by the following chemical formula 3: [Chemical Formula 3] LiFe r M 5 (1-r) XO4 In the above chemical formula 3, M 5 is at least one element selected from W, Cu, Fe, V, Cr, CO, Ni, Mn, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and X is at least one element among P, Si, S, As, and Sb, and r is 0≤r≤0.

9.

13. An electrode assembly comprising an anode according to claim 1, a cathode, and a separator interposed between the anode and the cathode, and A secondary battery comprising an electrolyte composition that impregnates the above electrode assembly.

14. In Paragraph 13, The above-mentioned negative electrode is a secondary battery comprising a negative active layer containing a carbon-based negative active material on at least one surface of a negative current collector.

15. In Paragraph 13, The above cathode active layer is made of Si, SiC, and SiO q A secondary battery further comprising at least one silicon-based negative electrode active material among (wherein 0.5≤q≤2.5).

Images