Electrode active material, its manufacturing method, electrode and secondary battery including the same

Abstract

Disclosed is an electrode active material including a compound represented by the following Chemical Formula 1, an electrode including the same, and a secondary battery including the same. [Chemical formula 1] Li x (Ni 1-y M y ) z (P 2 O 7 ) 4 In Chemical Formula 1, 5≦x≦7, 0.2≦y<1, 4≦z≦6, and M is an element selected from the group 3 to group 11 elements or a combination thereof, except that M is iron (Fe).

Description

[Technical Field]

[0001] The present invention relates to an electrode active material, a method for producing the same, and an electrode and a secondary battery including the same. [Background technology]

[0002] Recently, industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in the fields of information-related equipment and communication equipment, but also in the automotive field. In the automotive field, safety is of particular importance because life depends on it.

[0003] Currently, commercially available lithium-ion batteries are required to have increased energy density and power density per mass or volume, and to this end, efforts are being made to improve the voltage of positive electrode active materials.

[0004] Lithium-ion batteries use electrolytes containing flammable organic solvents, which can lead to overheating and fires if a short circuit occurs. In response to this, all-solid-state batteries using solid electrolytes instead of electrolytes have been proposed.

[0005] By not using flammable organic solvents, solid-state batteries can significantly reduce the risk of fire or explosion even if a short circuit occurs. Therefore, such solid-state batteries can be significantly safer than lithium-ion batteries that use liquid electrolytes. Because solid-state batteries can be charged beyond the voltage limit of liquid electrolytes, there is an increasing need for high-voltage cathode materials.

[0006] To implement a battery using a high-voltage positive electrode material, it is necessary to reduce the interfacial resistance between the solid electrolyte and the positive electrode material. When using a phosphate-based solid electrolyte, the interfacial resistance between the solid electrolyte and the positive electrode material can be reduced by using a phosphate-based positive electrode material. However, the discharge voltage of known phosphate-based positive electrode materials is very low, at 3 V.

[0007] In particular, due to the limited selection of anode materials available for multi-layer ceramic (MLC) batteries, ceramic anodes with high redox potentials are currently used, resulting in low full-cell voltages and very low energy densities. Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to provide a novel electrode active material that can be used at high voltages.

[0009] Another object of the present invention is to provide an electrode including the above-mentioned electrode active material and a secondary battery including the same.

[0010] A further object of the present invention is to provide a method for producing the above-mentioned electrode active material. [Means for solving the problem]

[0011] According to one aspect, an electrode active material is provided that includes a compound represented by Formula 1. [Chemical formula 1] Li x (Ni 1-y M y ) z (P2O7)4 In chemical formula 1, 5≦x≦7, 0.2≦y<1, 4≦z≦6, M is an element selected from the group 3 to group 11 elements or a combination thereof, except that M is iron (Fe).

[0012] Another aspect provides an electrode comprising the electrode active material described above.

[0013] According to yet another aspect, there is provided a secondary battery including the above-described electrode.

[0014] The secondary battery is a lithium secondary battery or an all-solid-state battery, and the all-solid-state battery is, for example, a multi-layer ceramic (MLC) battery.

[0015] According to yet another aspect, mixing a nickel precursor, a lithium precursor, a phosphorus precursor, and an M precursor to obtain a precursor mixture; The method for preparing an electrode active material comprising a compound represented by the following Formula 1 is provided, which includes the step of: heat-treating the mixture. [Chemical formula 1] Li x (Ni 1-y M y ) z (P2O7)4 In chemical formula 1, 5≦x≦7, 0.2≦y<1, 4≦z≦6, M is an element selected from the group 3 to group 11 elements or a combination thereof, excluding iron (Fe). [Effects of the Invention]

[0016] The present invention provides an electrode active material capable of high voltage operation and excellent stability. By using an electrode containing this electrode active material, a secondary battery having an average discharge voltage of 4.4 V or more and improved energy density can be manufactured. [Brief explanation of the drawings]

[0017] [Figure 1A] 1 is a diagram showing the results of X-ray diffraction analysis of the positive electrode active materials of Preparation Examples 1 to 4 and Comparative Preparation Examples 1 and 2. [Figure 1B] 1B is an enlarged view of a portion of FIG. 1A. [Figure 1C] 1 is a diagram showing X-ray diffraction analysis spectra for the positive electrode active materials of Preparation Examples 5, 6, and 7. [Figure 1D] 1 is a diagram showing X-ray diffraction analysis spectra for the positive electrode active materials of Preparation Example 6 and Comparative Preparation Example 1. [Figure 1E] 1 is a diagram showing X-ray diffraction analysis spectra for the positive electrode active materials of Comparative Preparation Examples 3 to 5. [Figure 2] 1 is a graph showing calculated values ​​of voltage change depending on the amount of cobalt and nickel mixed in a positive electrode active material. [Figure 3A] 1 is a graph showing voltage changes depending on specific capacitance in coin cells manufactured according to Examples 1-4 and Comparative Examples 1-2. [Figure 3B] 1 is a graph showing the change in specific capacity and average voltage depending on the amount of cobalt and nickel mixed in the positive electrode active material in the coin cells of Examples 1-4 and Comparative Examples 1-2. [Figure 4A] 1 is a graph showing voltage changes depending on specific capacitance in coin cells of Examples 1-2 and Comparative Example 1. [Figure 4B] 1 is a graph showing discharge curves normalized by capacity in coin cells of Examples 1-2 and Comparative Example 1. [Figure 4C] 10 is a graph showing voltage changes depending on specific capacitance in the coin cell of Comparative Example 4. [Figure 5] 1 is a diagram showing dQ / dV plots for coin cells of Examples 1-2 and Comparative Example 1. [Figure 6] 1 is a diagram schematically illustrating a structure of a multilayer ceramic battery according to an embodiment. [Figure 7] 10 is a diagram schematically illustrating a structure of a secondary battery according to another embodiment. [Figure 8] 10 is a diagram schematically illustrating a structure of a secondary battery according to yet another embodiment; [Figure 9A] 10 is a diagram schematically illustrating a structure of a secondary battery according to yet another embodiment; [Figure 9B] 10 is a diagram schematically illustrating a structure of a secondary battery according to yet another embodiment; [Figure 10] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to an embodiment. [Figure 11] FIG. 10 is a cross-sectional view of an all-solid-state secondary battery according to another embodiment. [Figure 12] FIG. 10 is a cross-sectional view of an all-solid-state secondary battery according to yet another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an electrode active material according to an embodiment, an electrode including the same, and a secondary battery will be described in detail.

[0019] An electrode active material is provided, which includes a compound represented by the following Chemical Formula 1: [Chemical formula 1] Li x (Ni 1-y M y ) z (P2O7)4 In Chemical Formula 1, 5≦x≦7, 0.2≦y<1, 4≦z≦6, and M is a Group 3 to Group 11 element or a combination thereof, with the proviso that M does not represent iron (Fe).

[0020] In Chemical Formula 1, 5.5≦x≦6.5, 0.2≦y<1, and 4.8≦z≦5.2.

[0021] x is a number from 5.8 to 6.2, y is a number from 0.3 to 0.9, and z is a number from 4.9 to 5.1.

[0022] In Chemical Formula 1, M is Co, Mn, V, Ti, Cr, Cu, Sc, Y, La, Zr, Hf, Nb, Ta, Mo, W, Tc, Re, Ru, Os, Co, Rh, Ir, Pd, Pt, Ag, Au, or a combination thereof, for example, M is Co, Mn, V, Ti, Cr, Cu, Sc, or a combination thereof.

[0023] The electrode active material is, for example, a positive electrode active material or a negative electrode active material.

[0024] To implement a battery using a cathode material that can handle high voltages, it is necessary to reduce the interfacial resistance between the solid electrolyte and the cathode material. When using a phosphate-based solid electrolyte, the interfacial resistance between the solid electrolyte and the cathode material can be reduced by using a phosphate-based cathode material. However, known phosphate-based cathode materials have a very low discharge voltage of 3V.

[0025] Multi-layer ceramic (MLC) batteries use ceramic-type anodes with high redox potentials as their anodes. However, the voltage and energy density of such MLC batteries are low, and improvements are needed.

[0026] Li6Fe5(P2O7)4 and Li6Co5(P2O7)4 are known as positive electrode materials. Among them, Li6Fe5(P2O7)4 has a low discharge voltage of 3.5 V, making it difficult to use at high voltages. Li6Co5(P2O7)4 has excellent stability, but its voltage characteristics are not satisfactory, and improvements are required.

[0027] The positive electrode active material according to one embodiment has excellent high-voltage discharge characteristics and phase stability by essentially containing nickel, which has excellent high-voltage characteristics, and a phase-stabilizing element, M, as represented by Chemical Formula 1. An electrode including such a positive electrode active material can be used to produce a high voltage of 4.4 V or more, 4.8 V or more, for example, 5 V or more, and can have an energy density of 800 Wh / kg, thereby enabling the production of a high-energy-density secondary battery.

[0028] According to one embodiment, the cathode active material is a Li6M5(P2O7)4-type cathode active material having a triclinic crystal structure and a space group (p-1). When M in Li6M5(P2O7)4 is nickel, the phase is very unstable. However, when M contains at least one element selected from Groups 3 to 11 other than Ni, the phase is stabilized, resulting in excellent discharge capacity in the high-voltage region.

[0029] The compound represented by Chemical Formula 1 is at least one selected from the compounds represented by Chemical Formulas 2 to 4 below.

[0030] [Chemical formula 2] Li x (Ni 1-y Co y ) z (P2O7)4 In Chemical Formula 2, 5 ≤ x ≤ 7, 0.2 ≤ y < 1, 4 ≤ z ≤ 6, [Chemical Formula 3] Li x (Ni 1-y Mn y ) z (P2O7)4 In Chemical Formula 3, 5 ≤ x ≤ 7, 0.2 ≤ y < 1, 4 ≤ z ≤ 6, [Chemical Formula 4] Li x (Ni 1-y-a Mn y A a ) z (P2O7)4 In Chemical Formula 4, 5 ≤ x ≤ 7, 0.2 ≤ y < 1, 4 ≤ z ≤ 6, 0 < a ≤ 0.2, and A is V, Nb, Ta, or a combination thereof.

[0031] In Chemical Formulas 2 to 4, 5.5 ≤ x ≤ 6.5, 0.2 ≤ y < 1, 4.8 ≤ z ≤ 5.2.

[0032] The compound represented by Chemical Formula 1 is, for example, Li6Ni2Co3(P2O7)4, Li6Ni3Co2(P2O7)4, Li6Ni1Co4(P2O7)4, Li6Ni4Co1(P2O7)4, Li6Mn3Ni2(P2O7)4, Li6Mn2Ni3(P2O7)4, Li6Mn2Ni1(P2O7)4, Li6Mn2V1Ni2(P2O7)4, Li6Mn2Nb1Ni2(P2O7)4, Li6Mn2Ta1Ni2(P2O7)4, Li6Tc3Ni2(P2O7)4, Li6Re3Ni2(P2O7)4, Li6Ni2Rh3(P2O7)4, Li6Ni1Rh4(P2O7)4, Li6Ni2Ir3(P2O7)4, Li6Ni1Ir4(P2O7)4, Li6Ni2V3(P2O7)4, Li6Ni1V4(P2O7)4, Li6Ni2Nb3(P2O7)4, Li6Ni1Nb4(P2O7)4, Li6Ni2Ta3(P2O7)4, Li6Ni1Ta4(P2O7)4, Li6Co2V1Ni2(P2O7) 4、Li6Co2V2Ni1(P2O7)4, Li6Ti3Ni2(P2O7), Li6Cr3Ni2(P2O7)4, Li6Cu3Ni2(P2O7)4, Li6Sc3Ni2(P2O7)4, or combinations thereof.

[0033] X-ray diffraction analysis using CuKα radiation of the compound of Chemical Formula 1 reveals a main peak in the region where the diffraction angle 2θ is 28.5±2°. The ratio (P2 / P1) of the main peak intensity (P1) to the minor peak intensity (P2) of the compound of Chemical Formula 1 revealed by X-ray diffraction analysis using CuKα radiation is 0.4 or less, 0.1 to 0.4, or 0.2 to 0.35.

[0034] In this specification, the term "main peak" refers to a peak having the greatest intensity, and the term "minor peak" refers to a peak having a second highest intensity that is lower than the main peak.

[0035] In the dQ / dV charge / discharge differential curve for a battery with an electrode containing the compound of formula 1, the dQ / dV peak voltage (dQ / dV peak voltage) showing the maximum discharge curve area at a current of 0.025 C and a voltage range of 3.0 V to 5.5 V was 4.7 V (vs. Li / Li + ) or more. The dQ / dV peak voltage, which indicates the maximum discharge curve area shown at a voltage of 3.0 V to 5.5 V at a current of 0.025 C in the dQ / dV charge / discharge differential curve, is, for example, 4.8 V (vs. Li / Li + ) or higher, 4.8 to 5.2V, or 4.8 to 5.15V.

[0036] In a dQ / dV charge / discharge differential curve for a battery including an electrode containing the compound of Chemical Formula 1 according to one embodiment, the ratio (A2 / A1) of the area (A2) of the discharge curve from 4.7 V to 5.5 V to the area (A1) of the discharge curve from 3.5 V to 5.5 V under the condition of a current of 0.025 C and a voltage of 3.0 V to 5.5 V is 0.4, 0.4 to 1.0, 0.43 to 0.55, or 0.434 to 0.531. The electrode may be, for example, a positive electrode.

[0037] The compound represented by Chemical Formula 1 according to an embodiment can be prepared by a wet or dry method. Hereinafter, a method for preparing the compound represented by Chemical Formula 1 by a dry method will be described.

[0038] First, a lithium precursor, a nickel precursor, a phosphorus precursor, and an M precursor are mixed to obtain a precursor mixture.

[0039] The mixing can be carried out, for example, by mechanical milling. During the mechanical milling, a solvent can be added, if necessary. The solvent can be, for example, acetone, ethanol, water, ethylene glycol, isopropanol, or a combination thereof. The content of the solvent is 50 to 1,000 parts by weight, for example, 100 to 300 parts by weight, based on 100 parts by weight of the total weight of the precursor compounds. When a solvent is added, the precursors can be mixed more uniformly.

[0040] Mechanical milling can be carried out by methods known in the art, such as using a ball mill, air jet mill, bead mill, roll mill, planetary ball mill, etc.

[0041] The lithium precursor may be, for example, one or more selected from lithium oxide, lithium carbonate, lithium chloride, lithium sulfide, lithium nitrate (LiNO3), lithium phosphate, and lithium hydroxide.

[0042] Examples of phosphorus precursors include (NH4)2HP04, (NH4)H2P04, LiPO3, and LiH2PO4.

[0043] Examples of the M precursor include an oxide containing an M element, a carbonate containing an M element, a chloride containing an M element, a phosphate containing an M element, a hydroxide containing an M element, a nitrate containing an M element, a hydroxide containing an M element, an oxalate containing an M element, or a mixture thereof, such as cobalt oxide, cobalt sulfate, cobalt hydroxide, cobalt nitrate, manganese oxide, manganese sulfate, manganese hydroxide, manganese nitrate, manganese oxalate, vanadium oxide, vanadium sulfate, vanadium hydroxide, vanadium nitrate, titanium oxide, titanium sulfate, titanium hydroxide, titanium nitrate, titanium oxalate, chromium oxide, chromium sulfate, chromium hydroxide, chromium nitrate, chromium oxalate, copper oxide, copper sulfate, copper hydroxide, copper nitrate, copper oxalate, cobalt oxalate, iron oxalate, or a mixture thereof.

[0044] The nickel precursor may be nickel oxide, nickel chloride, nickel sulfate, nickel nitrate, or a combination thereof, and the phosphorus precursor may be, for example, (NH4)2HP04, (NH4)H2P04, LiPO3, LiH2PO4, or a mixture thereof.

[0045] After the above-mentioned mixing, the resultant product is heat-treated to obtain the compound represented by Chemical Formula 1. The heat treatment is carried out at 500°C to 1000°C, 550°C to 900°C, or 600°C to 750°C. The heat treatment is carried out in an inert gas atmosphere or a reducing gas atmosphere. The inert gas atmosphere uses an inert gas such as argon or nitrogen, and the reducing gas atmosphere can be formed by mixing the above-mentioned inert gas with hydrogen at 3% by volume or less, or 0.1 to 3% by volume. The temperature rise rate during the heat treatment is 1°C / min to 10°C / min.

[0046] A drying process may be optionally performed before the heat treatment process. If drying is performed, the drying may be performed at 30°C to 150°C, 50°C to 130°C, 60°C to 120°C, or 80°C to 100°C. By performing the drying process in this manner, a positive electrode active material with even better energy density can be obtained.

[0047] The compound of Formula 1 can be prepared using a liquid phase method in addition to the solid phase method described above.

[0048] Another aspect provides an electrode comprising the above-described electrode active material. The electrode may be, for example, an electrode comprising a positive electrode active material or a negative electrode comprising a negative electrode active material.

[0049] The electrode active material according to an embodiment may be included in a negative electrode.

[0050] According to yet another aspect, there is provided a secondary battery including the electrode described above, wherein the electrode is a positive electrode or a negative electrode.

[0051] The secondary battery is a lithium secondary battery or an all-solid-state battery.

[0052] The all-solid-state battery can include, for example, a multi-layer-ceramic (MLC) battery.

[0053] The multilayer ceramic battery has a laminate structure in which a plurality of cell units, each including a positive electrode layer including a positive active material layer, a solid electrolyte layer, and a negative electrode layer including a negative active material layer, are stacked so that the positive electrode active material layer faces the negative electrode active material layer. According to another embodiment, the multilayer ceramic battery further includes a positive electrode current collector and / or a negative electrode current collector. When the multilayer ceramic battery includes a positive electrode current collector, the positive electrode active material layer may be disposed on both sides of the positive electrode current collector. When the multilayer ceramic battery includes a negative electrode current collector, the negative electrode active material layer may be disposed on both sides of the negative electrode current collector.

[0054] The multilayer ceramic battery includes a laminate in which a plurality of cell units, each having a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer arranged in succession, are stacked with the positive electrode active material layer and the negative electrode active material layer of each cell unit facing each other.

[0055] According to one embodiment, a current collector layer is provided on one or both of the uppermost and lowermost layers of the stack, or the cell units are stacked with a metal layer interposed between the stack.

[0056] The positive electrode active material and the secondary battery according to the embodiment may be used as a power source for applications for the Internet of Things (IoT), a power source for wearable devices, and the like.

[0057] The cathode active material according to an embodiment may be applied to thin film batteries and MLC batteries, and may also be applied to small batteries and large batteries such as those used in electric vehicles (EVs) and energy storage systems (ESSs).

[0058] The secondary battery is an all-solid-state secondary battery including a positive electrode layer including a positive electrode active material layer, a negative electrode layer including a negative electrode current collector layer and a first negative electrode active material layer or a third negative electrode active material layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and the positive electrode active material layer includes a positive electrode active material containing a compound represented by the following Chemical Formula 1. [Chemical formula 1] Li x (Ni 1-y M y ) z (P2O7)4 In chemical formula 1, 5≦x≦7, 0.2≦y<1, 4≦z≦6, M is an element selected from the group 3 to group 11 elements or a combination thereof, except that M is iron (Fe).

[0059] The first negative electrode active material layer includes at least one selected from the group consisting of a carbon-based negative electrode active material and a metal or semi-metal negative electrode active material.

[0060] The carbon-based negative electrode active material includes at least one selected from the group consisting of amorphous carbon and crystalline carbon, and the metal or semi-metal negative electrode active material includes at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

[0061] The battery further includes a second negative electrode active material layer disposed at least between the negative electrode current collector and the first negative electrode active material layer and between the solid electrolyte layer and the first negative electrode active material layer, and the second negative electrode active material layer is a metal layer containing lithium or a lithium alloy.

[0062] In the all-solid-state secondary battery according to one embodiment, the third negative electrode active material layer is a metal layer containing lithium or a lithium alloy.

[0063] The secondary battery according to one embodiment is also an all-solid-state micro secondary battery.

[0064] FIG. 6 is a diagram schematically illustrating the structure of an MLC battery according to an embodiment.

[0065] Referring to FIG. 6, the MLC battery can be fabricated by sequentially stacking an oxide electrode and a solid electrolyte and then simultaneously heat-treating them.

[0066] 6, a cathode 110 is formed by disposing a cathode active material layer 112 containing a cathode active material according to an embodiment on both sides of a cathode current collector 111. Anode active material layers 122 are laminated on both sides of an anode current collector 121 to form anode 120. A solid electrolyte 130 may be disposed between the cathode 110 and the anode 120, as shown in FIG. 6. External electrodes 140 are formed on both ends of the battery body 150. The external electrodes 140 are connected to the cathode 110 and the anode 120, whose ends are exposed to the outside of the battery body 150, and may serve as external terminals that electrically connect the cathode 110, the anode 120, and an external device. One of the pair of external electrodes 140 has one end connected to the cathode 110, whose end is exposed to the outside of the battery body 150, and the other has the other end connected to the anode 120, whose end is exposed to the outside of the battery body 150.

[0067] A secondary battery according to one embodiment is also a stacked solid-state battery including at least first and second cells, each of which is composed of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked in sequence, and an internal current collecting layer disposed between the first and second cells, in contact with the positive electrode layer of each of the first and second cells or in contact with the negative electrode layer of each of the first and second cells.

[0068] The negative electrode active material of the negative electrode active material layer is an oxide containing a Group 2 to Group 14 element, and includes, for example, lithium titanium oxide, lithium transition metal oxide, lithium metal phosphate, titanium oxide, vanadium oxide, or a combination thereof.

[0069] Lithium metal phosphate is Li3Fe2(PO4)3 or Li x V2(PO4)3(0 <x≦5)である。

[0070] The oxide anode is, for example, Li 4 / 3 Ti 5 / 3 O4, LiTiO2, LiM1 s M2 t O u (M1 and M2 are transition metals, and s, t, and u are each any positive number), TiO x (0 <x≦3),V2O5,Lix A lithium compound selected from the group consisting of V2(PO4)3(0 < x ≦ 5) and Li3Fe2(PO4)3 is included, for example, Li 4 / 3 Ti 5 / 3 O4, LiTiO2. TiO x (0 < x ≦ 3) includes, for example, TiO2.

[0071] The negative electrode active material is, for example, vanadium oxide (V2O5), Li4Ti5O 12 , TiO2, LiTiO2, Li3V2(PO4)3, Li3Fe2(PO4)3, or a combination thereof.

[0072] When the current collector layer functions as a positive electrode current collector and a negative electrode current collector, it is made of any metal among Ni, Cu, Ag, Pd, Au, and Pt, or also made of an alloy containing any of Ni, Cu, Ag, Pd, Au, and Pt. In the case of an alloy, it is an alloy of two or more selected from Ni, Cu, Ag, Pd, Au, and Pt, for example, an Ag / Pd alloy. Also, these metals and alloys can be alone or a mixture of two or more. The materials of the current collector layer as the positive electrode current collector and the current collector layer as the negative electrode current collector can be the same or different. In particular, an alloy or mixed powder containing Ag and Pd can continuously and arbitrarily change the melting point from the silver melting point (962 °C) to the palladium melting point (1550 °C) depending on the mixing ratio, so it is possible to adjust the melting point according to the batch firing temperature, and since the electronic conductivity is also high, there is an advantage that the internal resistance of the battery can be minimized.

[0073] The metal layer can use the same material as the current collector layer. The materials of the metal layer and the current collector layer can be the same or different.

[0074] The solid electrolyte contains an ion-conductive inorganic substance. For example, an oxide-based solid electrolyte can be used.

[0075] The oxide-based solid electrolyte is, for example, Li 1+x+y Al x Ti 2-x Si y P3-y O 12 (0 < x < 2, 0 ≤ y < 3), BaTiO3, Pb(Zr, Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (0 ≤ x < 1, 0 ≤ y < 1), Pb(Mg3Nb 2 / 3 )O3 - PbTiO3 (PMN - PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, SiC, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), lithium germanium thiophosphate (LixGeyPzSw, 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride - based glass (Li x N y , 0 < x < 4, 0 < y < 2), SiS2 (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5 - based glass (Li x P y S z 、0 < x < 3, 0 < y < 3, 0 < z < 7), Li2O, LiF, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2 - based ceramic, garnet - based ceramic Li 3+x La3M2O 12(M=Te, Nb, or Zr) (x is an integer of 1 to 10), or a combination thereof.

[0076] The solid electrolyte is, for example, Li 3.25 Al 0.25 SiO4, Li3PO4, LiP x Si y O z (wherein x, y, and z are any positive numbers from 1 to 1), for example, Li 3.5 P 0.5 Si 0.5 It is O4.

[0077] 7 and 8 are diagrams schematically showing the cross-sectional structure of a stacked solid state battery according to an embodiment.

[0078] 7, in a stacked solid state battery 710, a unit cell 1 and a unit cell 2 are stacked with an internal current collecting layer 74 interposed therebetween. Each of the unit cells 1 and 2 is composed of a positive electrode layer 71, a solid electrolyte layer 73, and a negative electrode layer 72, which are stacked in this order. The positive electrode layer 71 includes a positive electrode active material according to one embodiment.

[0079] The unit cells 1 and 2 and the internal current collecting layer 74 are stacked such that the negative electrode layer 72 of the unit cell 2 is adjacent to one side of the internal current collecting layer 74 (the upper side in FIG. 7 ) and the negative electrode layer 72 of the unit cell 1 is adjacent to the other side of the internal current collecting layer 74 (the lower side in FIG. 7 ). In FIG. 7 , the internal current collecting layer 74 is arranged so as to be in contact with the negative electrode layers 72 of the unit cells 1 and 2, respectively, but it may also be arranged so as to be in contact with the positive electrode layers 71 of the unit cells 1 and 2, respectively. The internal current collecting layer 74 contains an electron conductive material. The internal current collecting layer 74 may further contain an ion conductive material. If the internal current collecting layer 74 further contains an ion conductive material, excellent voltage stabilization characteristics will be obtained.

[0080] In the stacked solid state battery 710 according to the embodiment configured as described above, the same pole is arranged on both sides of the internal current collecting layer 4, so that a monopolar stacked solid state battery 710 is obtained in which a plurality of cells are connected in parallel via the internal current collecting layer 74. This results in a high-capacity stacked solid state battery 710.

[0081] Furthermore, in the stacked solid state battery 710, the internal current collecting layer 74 interposed between the cell 1 and the cell 2 contains an electronically conductive material, which electrically connects two adjacent cells in parallel and allows the positive electrode layers 71 or negative electrode layers 72 of the two adjacent cells to conduct through ionic conduction. This allows the potentials of the adjacent positive electrode layers 71 or negative electrode layers 72 to be averaged via the internal current collecting layer 74, thereby obtaining a stable output voltage.

[0082] Furthermore, external current collecting members such as pull-out tabs can be eliminated, and the cells constituting the stacked solid state battery 710 can be electrically connected in parallel, thereby providing a stacked solid state battery 710 with excellent space utilization and cost efficiency.

[0083] 8, the laminate includes a positive electrode layer 81, a negative electrode layer 82, a solid electrolyte layer 83, and an internal current collecting layer 84. Such laminates are stacked and thermocompression bonded to obtain a stacked solid state battery laminate 810. However, the positive electrode layer 81 is composed of one positive electrode layer sheet, and the negative electrode layer 82 is composed of two negative electrode layer sheets. The positive electrode layer 81 includes a positive electrode active material according to one example.

[0084] 9A and 9B are diagrams illustrating a stack of another embodiment of an all-solid-state secondary battery according to an embodiment. The positive electrode active material layer of FIG. 9A and FIG. 9B includes a positive electrode active material, which is an electrode active material according to an embodiment.

[0085] 9A, the structure of the most basic cell unit 92 constituting an all-solid-state secondary battery is shown. The cell unit 92 has a structure in which a positive electrode active material layer 94, an ion-conductive inorganic material layer 96, and a negative electrode active material layer 95 are successively arranged in this order.

[0086] FIG. 9B shows the structure of the laminate that constitutes the all-solid-state secondary battery.

[0087] In the all-solid-state secondary battery, a positive electrode extraction electrode is provided at the lower end in contact with the positive electrode active material layer, and a negative electrode extraction electrode is provided at the upper end in contact with the negative electrode active material layer. In this specification, the upper end and the lower end indicate a relative positional relationship.

[0088] The laminate 923 has a structure in which a plurality of cell units 92 are stacked such that the positive electrode active material layer 94 and the negative electrode active material layer 95 of each cell unit 92 face each other, and the uppermost and lowermost current collector layers are provided. One of the uppermost and lowermost current collector layers is connected to the positive electrode active material layer to form a positive electrode current collector, and the other is connected to the negative electrode active material layer to form a negative electrode current collector. The lowermost current collector layer 97 is in contact with the positive electrode active material layer 94 to form a positive electrode current collector, and the uppermost current collector layer 98 is in contact with the negative electrode active material layer 95 to form a negative electrode current collector.

[0089] In this embodiment, the current collector layers can function as extraction electrodes. In Fig. 9B, the bottom current collector layer 97 can function as the positive electrode extraction electrode, and the top current collector layer 8 can function as the negative electrode extraction electrode. Alternatively, extraction electrodes can be separately provided on the current collector layers, for example, a positive electrode extraction electrode in contact with current collector layer 97 at the bottom and a negative electrode extraction electrode in contact with current collector layer 98 at the top.

[0090] 9B, the stack 923 has a structure in which the cell units 92 are stacked with a metal layer 920 interposed therebetween. By interposing the metal layer, ion movement is confined within the individual cell units, and it is expected that the battery will function more reliably as a series-connected all-solid-state secondary battery. Although the stack 923 in FIG. 9B includes a current collector layer, the current collector layer is optional as described above.

[0091] In the stack of the all-solid-state secondary battery, a so-called series-type all-solid-state secondary battery can be formed if the number of cell units 92 is two or more. The number of cell units can be changed widely based on the required capacity and voltage value of the all-solid-state secondary battery.

[0092] The secondary battery according to the embodiment is also an all-solid-state secondary battery. Hereinafter, the all-solid-state secondary battery according to the embodiment will be described in more detail with reference to the accompanying drawings.

[0093] 10 to 12, the all-solid-state secondary battery 1 includes an anode layer 20 including an anode current collector layer 21 and a first anode active material layer 22; a cathode layer 10 including a cathode current collector layer 11 and a cathode active material layer 12; and a solid electrolyte layer 30 disposed between the anode layer 20 and the cathode layer 10. The cathode layer 10 includes a solid electrolyte. The cathode active material layer and / or the anode active material layer of FIGS. 10 to 12 include an electrode active material according to an embodiment.

[0094] The positive electrode layer includes, for example, the above-described positive electrode active material, solid electrolyte, and conductive material.

[0095] (negative electrode layer) 10 to 12, the negative electrode layer 20 includes a negative electrode current collector layer 21 and a first negative electrode active material layer 22. The first negative electrode active material layer 22 includes a negative electrode active material. The negative electrode current collector layer 21 may be omitted.

[0096] The negative electrode active material contained in the first negative electrode active material layer 22 has, for example, a particulate form. The average particle size of the particulate negative electrode active material is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle size of the particulate negative electrode active material is, for example, 10 nm to 4 μm, 10 nm to 2 μm, 10 nm to 1 μm, or 10 nm to 900 nm. When the negative electrode active material has an average particle size within such a range, reversible absorbing and / or desorbing of lithium during charging and discharging is further facilitated. The average particle size of the negative electrode active material is, for example, the median diameter (D50) measured using a laser particle size distribution analyzer.

[0097] The negative electrode active material contained in the first negative electrode active material layer 22 includes, for example, one or more selected from a carbon-based negative electrode active material and a metal or semi-metal negative electrode active material.

[0098] The carbon-based negative electrode active material is particularly amorphous carbon. Examples of amorphous carbon include, but are not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene. Any amorphous carbon classified as amorphous carbon in the art can be used. Amorphous carbon is carbon that has no or very low crystallinity and is distinguished from crystalline carbon or graphite-based carbon.

[0099] The metal or semimetal negative electrode active material may include, but is not limited to, one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Any metal or semimetal negative electrode active material known in the art that forms an alloy or compound with lithium may be used. For example, nickel (Ni) is not a metal negative electrode active material because it does not form an alloy with lithium.

[0100] The first negative electrode active material layer 22 may include one of these negative electrode active materials or a mixture of multiple different negative electrode active materials. For example, the first negative electrode active material layer 22 may include only amorphous carbon, or may include one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the first negative electrode active material layer 22 may include a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio or weight ratio of the mixture of amorphous carbon and gold or the like is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to such ranges and is selected depending on the required characteristics of the all-solid-state secondary battery 1. When the negative electrode active material has such a composition, the cycle characteristics of the all-solid-state secondary battery 1 are further improved.

[0101] The negative electrode active material contained in the first negative electrode active material layer 22 includes, for example, a mixture of first particles made of amorphous carbon and second particles made of a metal or a metalloid. Examples of the metal or metalloid include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). In other embodiments, the metalloid is also a semiconductor. The content of the second particles is 8 to 60 wt %, 10 to 50 wt %, 15 to 40 wt %, or 20 to 30 wt %, based on the total weight of the mixture. When the content of the second particles is within such a range, for example, the cycle characteristics of the all-solid-state secondary battery 1 are further improved.

[0102] The first negative electrode active material layer 22 includes, for example, a binder. Examples of the binder include, but are not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. Any binder known in the art can be used. The binder can be a single binder or a combination of multiple different binders.

[0103] The inclusion of a binder in the first negative electrode active material layer 22 stabilizes the first negative electrode active material layer 22 on the negative electrode current collector 21. Furthermore, cracking of the first negative electrode active material layer 22 is suppressed despite volume changes and / or relative position changes of the first negative electrode active material layer 22 during charge and discharge. For example, if the first negative electrode active material layer 22 does not include a binder, the first negative electrode active material layer 22 can be easily separated from the negative electrode current collector 21. When the first negative electrode active material layer 22 is separated from the negative electrode current collector 21, the negative electrode current collector 21 is exposed and comes into contact with the solid electrolyte layer 30, increasing the possibility of short circuiting. The first negative electrode active material layer 22 is prepared, for example, by applying a slurry, in which materials constituting the first negative electrode active material layer 22 are dispersed, onto the negative electrode current collector 21 and drying the slurry. The inclusion of a binder in the first negative electrode active material layer 22 allows the negative electrode active material to be stably dispersed in the slurry. For example, when the slurry is applied onto the negative electrode current collector 21 by screen printing, clogging of the screen (for example, clogging due to aggregates of the negative electrode active material) can be suppressed.

[0104] The thickness (d22) of the first negative electrode active material layer is, for example, 50% or less, 30% or less, 10% or less, or 5% or less of the thickness (d12) of the positive electrode active material layer. The thickness (d22) of the first negative electrode active material layer is, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. When the thickness (d22) of the first negative electrode active material layer is in this range, the cycle characteristics of the all-solid-state secondary battery 1 are excellent.

[0105] The charge capacity of the first negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 2% or less of the charge capacity of the positive electrode active material layer 12. The charge capacity of the first negative electrode active material layer 22 is, for example, 0.1% to 50%, 0.1% to 40%, 0.1% to 30%, 0.1% to 20%, 0.1% to 10%, 0.1% to 5%, or 0.1% to 2% of the charge capacity of the positive electrode active material layer 12. When the charge capacity of the first negative electrode active material layer 22 is in the above range, the all-solid-state secondary battery 1 has excellent cycle characteristics. The charge capacity of the positive electrode active material layer 12 is obtained by multiplying the charge capacity density (mAh / g) of the positive electrode active material by the mass of the positive electrode active material of the positive electrode active material layer 12. The negative electrode current collector 21 is made of, for example, a material that does not react with lithium, i.e., does not form any alloy or compound. Materials constituting the negative electrode current collector 21 include, but are not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material used as an electrode current collector in the art can be used. The negative electrode current collector 21 can be made of one of the above-mentioned metals, or an alloy or coating material of two or more metals. The negative electrode current collector 21 is, for example, in the form of a plate or foil.

[0106] The first negative electrode active material layer 22 may further contain additives used in conventional all-solid-state secondary batteries 1, such as a filler, a dispersant, an ion conductive agent, and the like.

[0107] Referring to FIG. 11 , the all-solid-state secondary battery 1 further includes a thin film 24 on the anode current collector 21, the thin film 24 including an element capable of forming an alloy with lithium. The thin film 24 is disposed between the anode current collector 21 and the first anode active material layer 22. The thin film 24 includes, for example, an element capable of forming an alloy with lithium. Examples of elements capable of forming an alloy with lithium include, but are not limited to, gold, silver, zinc, tin, indium, silicon, aluminum, and bismuth. Any element known in the art that forms an alloy with lithium can be used. The thin film 24 may be composed of one of these metals or an alloy of multiple metals. By disposing the thin film 24 on the anode current collector 21, the deposition morphology of the second anode active material layer (not shown) deposited between the thin film 24 and the first anode active material layer 22 may be more even, thereby further improving the cycle characteristics of the all-solid-state secondary battery 1.

[0108] The thickness (d24) of the thin film is, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thickness of the thin film is within the above range, the energy density and cycle characteristics of the all-solid-state battery are excellent. The thin film 24 can be disposed on the negative electrode current collector 21 by, for example, vacuum deposition, sputtering, plating, or the like, but is not necessarily limited to such methods, and any method for forming the thin film 24 known in the art can be used.

[0109] 12 , the all-solid-state secondary battery 1 further includes, for example, a second anode active material layer 23 disposed between the anode current collector 21 and the solid electrolyte layer 30 upon charging. The all-solid-state secondary battery 1 further includes, for example, a second anode active material layer 23 disposed between the anode current collector 21 and the first anode active material layer 22 upon charging. Although not shown in the drawing, the all-solid-state secondary battery 1 further includes, for example, a second anode active material layer 23 disposed between the solid electrolyte layer 30 and the first anode active material layer 22 upon charging. Although not shown in the drawing, the all-solid-state secondary battery 1 further includes, for example, a second anode active material layer 23 disposed within the first anode active material layer 22 upon charging.

[0110] The second negative electrode active material layer 23 is a metal layer containing lithium or a lithium alloy. The metal layer contains lithium or a lithium alloy. Therefore, since the second negative electrode active material layer 23 is a metal layer containing lithium, it functions, for example, as a lithium reservoir. Examples of lithium alloys include, but are not limited to, Li-Al alloys, Li-Sn alloys, Li-In alloys, Li-Ag alloys, Li-Au alloys, Li-Zn alloys, Li-Ge alloys, and Li-Si alloys. Any lithium alloy known in the art can be used. The second negative electrode active material layer 23 may be composed of one of these alloys or lithium, or may be composed of multiple alloys.

[0111] The thickness (d23) of the second negative electrode active material layer is not particularly limited, and is, for example, 1 μm to 1000 μm, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. When the thickness (d23) of the second negative electrode active material layer is within this range, the cycle characteristics of the all-solid-state secondary battery are excellent. The second negative electrode active material layer 23 can also be, for example, a metal foil having a thickness within this range.

[0112] In the all solid state secondary battery 1, the second negative electrode active material layer 23 is, for example, disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before the all solid state secondary battery 1 is assembled, or is deposited between the negative electrode current collector 21 and the first negative electrode active material layer 22 by charging after the all solid state secondary battery 1 is assembled.

[0113] When the second negative electrode active material layer 23 is disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before assembling the all solid state secondary battery 1, the second negative electrode active material layer 23 is a metal layer containing lithium and therefore acts as a lithium reservoir. The cycle characteristics of the all solid state secondary battery 1 including the second negative electrode active material layer 23 are further improved. For example, a lithium foil is disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before assembling the all solid state secondary battery 1.

[0114] When the second anode active material layer 23 is disposed by charging after the all-solid-state secondary battery 1 is assembled, the energy density of the all-solid-state secondary battery 1 increases because the second anode active material layer 23 is not included during assembly of the all-solid-state secondary battery 1. For example, when charging the all-solid-state secondary battery 1, the first anode active material layer 22 is charged beyond its charge capacity. That is, the first anode active material layer 22 is overcharged. At the initial stage of charging, lithium is absorbed into the first anode active material layer 22. That is, the anode active material contained in the first anode active material layer 22 forms an alloy or compound with lithium ions transferred from the positive electrode layer 10. When the first anode active material layer 22 is charged beyond its capacity, for example, lithium is deposited on the back surface of the first anode active material layer 22, i.e., between the anode current collector 21 and the first anode active material layer 22, and the deposited lithium forms a metal layer corresponding to the second anode active material layer 23. The second negative electrode active material layer 23 is a metal layer composed mainly of lithium (i.e., metallic lithium). This result is achieved, for example, because the negative electrode active material contained in the first negative electrode active material layer 22 is composed of a material that forms an alloy or compound with lithium. During discharge, lithium in the first negative electrode active material layer 22 and the second negative electrode active material layer 23, i.e., the metal layer, is ionized and moves toward the positive electrode layer 10. This allows lithium to be used as the negative electrode active material in the all-solid-state secondary battery 1. Furthermore, the first negative electrode active material layer 22 covers the second negative electrode active material layer 23, thereby serving as a protective layer for the second negative electrode active material layer 23, i.e., the metal layer, and also serving to suppress the precipitation and growth of lithium dendrites. This prevents short circuits and capacity reduction in the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. Furthermore, when the second negative electrode active material layer 23 is disposed by charging after the all solid state secondary battery 1 is assembled, the negative electrode current collector 21, the first negative electrode active material layer 22, and the region therebetween are, for example, Li-free regions that do not contain lithium (Li) metal or lithium (Li) alloy in the initial state or after discharge of the all solid state secondary battery.

[0115] 12, the all-solid-state secondary battery 1 has a structure in which a second anode active material layer 23 is disposed on a negative electrode current collector 21, and a solid electrolyte layer 30 is disposed directly on the second anode active material layer 23. The second anode active material layer 23 is, for example, a lithium metal layer or a lithium alloy layer.

[0116] (solid electrolyte layer) 10 to 12, the solid electrolyte layer 30 includes an oxide-based solid electrolyte.

[0117] The oxide-based solid electrolyte is, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2、0≦y<3)、BaTiO3、Pb(Zr、Ti)O3(PZT)、Pb 1-x La x Zr 1-y Ti y O3(PLZT)(O≦x<1, O≦y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2、0<y<3)、Li x Al y Ti z (PO4)3(0 <x<2、0<y<1、0<z<3)、Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≦x≦10≦y≦1), Li x La y TiO3(0 <x<2、0<y<3)、Li2O、LiOH、Li2CO3、LiAlO2、Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2、Li 3+x La3M2O 12(M=Te, Nb, or Zr, x is an integer of 1 to 10).

[0118] The oxide-based solid electrolyte is, for example, Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (LLZO doped with M, M=Ga, W, Nb, Ta, or Al, x is an integer of 1 to 10, 0.05≦a≦0.7) is a garnet-type solid electrolyte selected from the group consisting of:

[0119] According to one embodiment, the solid electrolyte layer comprises an LLZO solid electrolyte.

[0120] The solid electrolyte layer is, for example, Li7La3Zr2O 12 (LLZO), Li 6.4 La3Zr 1.7 W 0.3 O 12、 Li 6.5 La3Zr 1.5 Ta 0.3 O 12、 Li7La3Zr 1.7 W 0.3 O 12 , Li 4.9 La 2.5 Ca 0.5 Zr 1.7 Nb 0.3 O 12、 Li 4.9 Ga 2.1 La3Zr 1.7 W 0.3 O 12 , Li 6.4 La3Zr 1.7 W 0.3 O 12 , Li7La3Zr 1.5 W 0.5 O 12 , Li7La 2.75 Ca 0.25 Zr 1.75 Nb 0.25 O 12 , Li7La3Zr 1.5 Nb 0.5 O12 , Li7La3Zr 1.5 Ta 0.5 O 12 , Li 6.272 La3Zr 1.7 W 0.3 O 12 , Li 5.39 Ga 1.61 La3Zr 1.7 W 0.3 O 12 , Li 6.5 La3Zr 1.5 Ta 0.3 O 12 , or a combination thereof.

[0121] (positive electrode layer) The positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 .

[0122] The positive electrode current collector 11 is, for example, a plate or foil made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The positive electrode current collector 11 is optional.

[0123] The cathode active material layer 12 includes a cathode active material and a solid electrolyte. The solid electrolyte included in the cathode layer 10 may be similar to or different from the solid electrolyte included in the solid electrolyte layer 30. For details regarding the solid electrolyte, refer to the solid electrolyte layer 30 section. According to an embodiment, the solid electrolyte may include an oxide-based solid electrolyte.

[0124] The positive electrode layer includes a positive electrode active material, which is an electrode active material according to one embodiment.

[0125] The shape of the positive electrode active material is, for example, a particle shape such as a spherical shape or an elliptical shape. The particle size of the positive electrode active material is not particularly limited, and is within a range applicable to positive electrode active materials of conventional all-solid-state secondary batteries. The content of the positive electrode active material in the positive electrode layer 10 is also not particularly limited, and is within a range applicable to positive electrode layers of conventional all-solid-state secondary batteries.

[0126] In addition to the above-described positive electrode active material and solid electrolyte, the positive electrode layer 10 may further include additives such as a conductive agent, a binder, a filler, a dispersant, and an ion-conducting aid. Examples of such conductive agents include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, and metal powder. Examples of binders include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Known materials commonly used in electrodes for solid-state secondary batteries can be used as coating agents, dispersants, and ion-conducting aids that can be incorporated into the positive electrode layer 10.

[0127] The all-solid-state secondary battery is manufactured by laminating a solid electrolyte layer 30 on top of a positive electrode layer 10, and laminating a negative electrode layer 20 on top of that.

[0128] According to another embodiment, the solid electrolyte layer 30 may be formed by coating a solid electrolyte layer-forming composition on a separate substrate, drying the coating, and separating the solid electrolyte layer from the substrate, or by forming a sheet containing the substrate. Non-limiting examples of the substrate include a polyethylene terephthalate film and a polyethylene nonwoven fabric.

[0129] According to yet another embodiment, the solid electrolyte layer 30 may be formed by coating a composition for forming a first solid electrolyte layer on the cathode layer 10 and drying or transferring the composition.

[0130] The positive electrode layer, the solid electrolyte layer, and the negative electrode layer may then be packaged in a packaging material and pressed to produce an all-solid-state battery. Pressing may be performed using a roll press, a hot press, a warm isostatic press, or the like.

[0131] When pressurizing, roll pressurization or hot pressurization can be used for mass production, and a tight interface can be formed during the compression process between the electrode layer and the solid electrolyte layer.

[0132] (Production of negative electrode layer) A slurry is prepared by adding materials constituting the first negative electrode active material layer 22, such as a negative electrode active material, a conductive material, a binder, and a solid electrolyte, to a polar or non-polar solvent. The prepared slurry is applied to the negative electrode current collector 21 and dried to prepare a first laminate. The dried first laminate is then pressed to prepare the negative electrode layer 20. The pressing method may be, for example, a roll press or a flat press, but is not limited to these methods and any pressing method commonly used in the art may be used. The pressing step may be omitted.

[0133] The negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer including a negative electrode active material disposed on the negative electrode current collector, the negative electrode active material including at least one selected from a carbon-based negative electrode active material and a metal or semimetal negative electrode active material, the carbon-based negative electrode active material including at least one selected from amorphous carbon and crystalline carbon, and the metal or semimetal negative electrode active material being at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

[0134] The battery further includes a second negative electrode active material layer disposed at least between the negative electrode current collector and the first negative electrode active material layer and between the solid electrolyte layer and the first negative electrode active material layer, and the second negative electrode active material layer is a metal layer containing lithium or a lithium alloy.

[0135] (Production of positive electrode layer) A slurry is prepared by adding materials constituting the positive electrode active material layer 12, such as a positive electrode active material, a conductive material, a binder, and a solid electrolyte, to a non-polar solvent. The positive electrode active material according to one embodiment is used as the positive electrode active material. The prepared slurry is applied to a positive electrode current collector 11 and dried. The resulting laminate is pressed to prepare the positive electrode layer 10. The pressing method may be, for example, a roll press, a flat press, or a hydrostatic press, but is not limited to these methods. Any pressing method commonly used in the art may be used. The pressing step may be omitted. Alternatively, the positive electrode layer 10 may be prepared by compacting a mixture of materials constituting the positive electrode active material layer 12 into a pellet or by stretching it into a sheet. When preparing the positive electrode layer 10 using this method, the positive electrode current collector 11 may be omitted.

[0136] (Manufacturing of solid electrolyte layer) The solid electrolyte layer 30 is manufactured by using, for example, a solid electrolyte formed from an oxide-based solid electrolyte material.

[0137] (Manufacturing all-solid-state secondary batteries) The positive electrode layer 10, the negative electrode layer 20, and the solid electrolyte layer 30 produced by the above-described method are stacked with the positive electrode layer 10 and the negative electrode layer 20 sandwiching the solid electrolyte layer 30, and then pressurized to produce an all-solid-state secondary battery 1.

[0138] For example, a second laminate is prepared by disposing a solid electrolyte layer 30 on a positive electrode layer 10. Then, an anode layer 20 is disposed on the second laminate so that the solid electrolyte layer 30 and the first anode active material layer are in contact with each other, thereby producing an all-solid-state secondary battery 1.

[0139] The configuration and manufacturing method of the all-solid-state secondary battery described above are one example of an embodiment, and the constituent materials, manufacturing procedures, etc. can be appropriately changed.

[0140] The all-solid-state secondary battery according to an embodiment can be installed in a small ITS or a large electric vehicle depending on the capacity and size of the battery.

[0141] The present invention will be specifically described below with reference to examples and comparative examples, but is not limited to the following examples.

[0142] (Production of positive electrode active material) Manufacturing Example 1 Li2CO3, CoO, NiO, and (NH4)2HPO4 were mixed to obtain a precursor mixture, which was then mixed with ethanol and milled in a ball mill for 10 hours. The contents of Li2CO3, CoO, NiO, and (NH4)2HPO4 were stoichiometrically controlled to obtain a cathode active material having the composition shown in Table 1 below, and 100 parts by weight of ethanol was used based on 100 parts by weight of the total content of Li2CO3, CoO, NiO, and (NH4)2HPO4.

[0143] The milled product was dried at 90°C for 12 hours, and the dried product was heat-treated in an air atmosphere at 750°C for 12 hours to obtain the positive electrode active material Li6Co4Ni1(P2O7)4.

[0144] Manufacturing Example 2-4 A cathode active material having the composition shown in Table 1 below was obtained by the same procedure as in Preparation Example 1, except that the contents of Li2CO3, CoO, NiO, and (NH4)2HPO4 were stoichiometrically controlled during the preparation of the precursor mixture so as to obtain a target product having the composition shown in Table 1 below.

[0145] Manufacturing Example 5 The same procedure as in Preparation Example 1 was carried out to prepare a precursor mixture, except that MnO2 was used instead of CoO, to obtain a positive electrode active material having the composition shown in Table 1 below.

[0146] Manufacturing Example 6 A cathode active material having the composition shown in Table 1 below was obtained by the same method as in Preparation Example 1, except that MnO was used instead of CoO when preparing the precursor mixture and the heat treatment temperature was changed to 700°C.

[0147] Manufacturing Example 7 A cathode active material having the composition shown in Table 1 below was obtained by the same method as in Preparation Example 1, except that MnO and V2O3 were used instead of CoO when preparing the precursor mixture and the heat treatment temperature was changed to 600°C.

[0148] Comparative Manufacturing Example 1 The precursor mixture was prepared in the same manner as in Preparation Example 1, except that NiO was not used, to obtain a positive electrode active material having the composition shown in Table 1 below.

[0149] Comparative Manufacturing Example 2 The precursor mixture was prepared in the same manner as in Preparation Example 1, except that CoO was not used, to obtain a positive electrode active material having the composition shown in Table 1 below.

[0150] Comparative Manufacturing Example 3 Li2CO3, FeC2O4·2H2O, NiC2O4·2H2O, and (NH4)2HPO4 were placed in a planetary ball mill container. The planetary ball mill container was then placed in a ball mill device, and the ball mill device was turned on to mix the raw materials. The contents of Li2CO3, FeC2O4·2H2O, NiC2O4·2H2O, and (NH4)2HPO4 were stoichiometrically adjusted to obtain the desired products shown in Table 1 below.

[0151] The mixture obtained through the above process was fired at 800° C. for 6 hours in an argon atmosphere to obtain a positive electrode active material having the composition shown in Table 1 below.

[0152] Comparative Manufacturing Example 4-5 Li2CO3, FeC2O4·2H2O, NiC2O4 . The same procedure as in Comparative Preparation Example 3 was carried out, except that the contents of 2H2O and (NH4)2HPO4 were stoichiometrically adjusted to obtain the target products shown in Table 1 below, to obtain positive electrode active materials having the compositions shown in Table 1 below.

[0153] [Table 1]

[0154] Li6Ni5(P2O7)4 obtained by Comparative Production Example 2 has a high discharge voltage, but it is difficult to maintain a stable phase. 2.5 Ni 2.5 As shown in Figure 4C below, (P2O7)4 did not exhibit high voltage discharge of 5 V or more.

[0155] Manufacturing Example 8-11 The same procedure as in Preparation Example 1 was carried out to prepare the precursor mixture, except that titanium oxide (TiO), CrO, CuO, and ScO were used instead of CoO, to obtain positive electrode active materials having the compositions shown in Table 2 below.

[0156] [Table 2]

[0157] (Lithium secondary battery manufacturing) Example 1 First, a positive electrode was prepared by the following process.

[0158] A composition for forming a positive electrode active material layer was prepared by mixing the positive electrode active material of Preparation Example 1, a conductive agent (Super-P; Timcal Ltd.), polyvinylidene fluoride (PVdF), and N-methylpyrrolidone. In the composition for forming a positive electrode active material layer, the mixing ratio of LiCoNi(P0), the conductive agent, and PVDF was 50:30:20 by weight, and the amount of N-methylpyrrolidone was approximately 20 g per 1 g of positive electrode active material.

[0159] The composition for forming a positive electrode active material layer was coated on an aluminum foil (thickness: about 15 μm) and dried at 25°C. The dried resultant was then dried in a vacuum at about 120°C and rolled to prepare a positive electrode having a thickness of about 5.5 μm.

[0160] A 2032-type coin cell was fabricated using a lithium metal counter electrode as the positive electrode and a porous polyethylene (PE) film separator (approximately 16 μm thick) between the positive electrode and the lithium metal counter electrode, and an electrolyte was injected to fabricate a 2032-type coin cell-type lithium secondary battery. The electrolyte used was a solution containing 1.1 M LiPF6 dissolved in a solvent made of a 3:5 volumetric mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC).

[0161] Example 2-11 Lithium secondary batteries were manufactured in the same manner as in Example 1, except that the positive electrode active materials of Preparation Examples 2 to 11 were used instead of the positive electrode active material of Preparation Example 1.

[0162] Comparative Examples 1-5 Lithium secondary batteries were manufactured in the same manner as in Example 1, except that the positive electrode active materials of Comparative Preparation Examples 1 to 5 were used instead of the positive electrode active material of Preparation Example 1.

[0163] Evaluation example 1: X-ray diffraction analysis X-ray diffraction analysis was carried out on the positive electrode active materials of Preparation Examples 1-4 and Comparative Preparation Examples 1-5 using X'pert pro (PANalytical) with CuKα radiation (1.54056 Å).

[0164] The results of X-ray diffraction analysis of the positive electrode active materials of Preparation Examples 1-4 and Comparative Preparation Examples 1-2 are shown in FIG. 1A, and a partial enlarged view of FIG. 1B is shown in FIG. 1A and FIG. 1B. For reference, Li 5.88 Co 5.06 (P2O7)4 is also shown.

[0165] 1A and 1B, it was found that the positive electrode active material of Preparation Example 1-4 was able to maintain a stable crystalline phase by incorporating cobalt, which has high phase stability.

[0166] The positive electrode active material of Comparative Preparation Example 1 had excellent phase stability, but the positive electrode active material of Comparative Preparation Example 2 was very unstable in phase, changing into other substances such as Li2Ni3(P2O7)2 and LiNiPO4 in the temperature range of 500 to 900°C.

[0167] In addition, the intensity ratios of the main peak and the minor peak determined by X-ray diffraction analysis for the positive electrode active material of Preparation Example 1-2 and the positive electrode active material of Comparative Preparation Example 1 were measured using the following formula 1 and are shown in Table 3. Here, the main peak is the peak showing the maximum absorption intensity and is indicated in the region where the diffraction angle 2θ is 28.5°, and the minor peak is a peak with a smaller absorption intensity than the main peak and is indicated in the region where the diffraction angle 2θ is 14.3°.

[0168] [Formula 1] Peak intensity ratio (P2 / P1) = minor peak intensity (P2) / main peak intensity (P1)

[0169] [Table 3]

[0170] It can be seen from Table 3 that the positive electrode active materials of Preparation Examples 1 and 2 are distinguished from the positive electrode active material of Comparative Preparation Example 1 in terms of physical properties such as crystallinity.

[0171] (2) Preparation Examples 5, 6 and 7 The X-ray diffraction analysis spectra of the positive electrode active materials of Preparation Examples 5, 6, and 7 are shown in FIG. 1C. For reference, Li 5.88 Co 5.06 (P2O7)4 is also shown.

[0172] Referring to FIG. 1C, it was found that the positive electrode active materials of Preparation Examples 5 to 7 had high phase stability because some nickel sites were substituted with other transition metals such as manganese or vanadium.

[0173] (3) Production Example 6 and Comparative Production Example 1 The X-ray diffraction analysis spectra of the positive electrode active materials of Preparation Example 6 and Comparative Preparation Example 1 are shown in FIG. 1D. For reference, FIG. 1D also shows the X-ray diffraction analysis spectra of Li 5.88 Co 5.06 (P2O7)4 is also shown.

[0174] Referring to FIG. 1D, it was found that the positive electrode active material of Preparation Example 6 has excellent phase stability because some nickel sites are substituted with manganese and vanadium.

[0175] (4) Comparative Manufacturing Example 3-5 The results of X-ray diffraction analysis of the positive electrode active materials of Comparative Preparation Examples 3 to 5 are shown in FIG. 1E.

[0176] 1E, the positive electrode active materials of Comparative Preparation Examples 3 to 5 had excellent phase stability, but as can be seen from the voltage change graph as a function of specific capacity described below, the high voltage characteristics were poor.

[0177] Evaluation example 2: Voltage calculation Cathode active material Li6Co 5-x The voltage was calculated for Nix(P2O7)4 depending on the amount of cobalt and nickel mixed. The voltage calculation was performed using quantum calculations. The quantum calculations were performed using density functional theory (DFT).

[0178] The voltage calculation results are shown in Figure 2.

[0179] Referring to Figure 2, in order to use a positive electrode active material with high voltage characteristics, nickel in the positive electrode active material was replaced with cobalt, which has excellent phase stability, and a high average voltage of 4.8 V or more was achieved while stably maintaining the crystal structure.

[0180] Evaluation example 3: Charge / discharge characteristics (1) Examples 1-4 and Comparative Examples 1-2 The charge-discharge characteristics of the coin cells manufactured in Examples 1-4 and Comparative Examples 1-2 were evaluated by the following charge-discharge test.

[0181] After leaving the cells at 25°C for 5 hours, they were charged at a constant current of 0.1C until the voltage reached 5.5V. The charged cells were then discharged at a constant current of 0.025C until the voltage reached 4.0V.

[0182] This charge-discharge cycle was repeated a total of 10 times. Some of the results are shown in Figures 3A and 3B. Figure 3A shows the voltage change as a function of specific capacity for the coin cells fabricated in Examples 1-4 and Comparative Examples 1-2. Figure 3B shows the specific capacity and average voltage change as a function of the amount of cobalt and nickel mixed in the positive electrode active material for the coin cells fabricated in Examples 1-4 and Comparative Examples 1-2.

[0183] 3A and 3B, the coin cells of Examples 1 to 5 exhibited superior average voltage, specific capacity, and charge / discharge characteristics compared to the coin cells of Comparative Examples 1 and 2.

[0184] The average voltage and specific capacitance characteristics of the coin cells of Examples 5-11 were evaluated in the same manner as in Example 1.

[0185] As a result of the evaluation, the average voltage and specific capacitance characteristics of the coin cells of Examples 5-11 showed excellent results similar to those of the coin cell of Example 1.

[0186] (2) Examples 1-2 and Comparative Examples 3-5 The charge-discharge characteristics of the coin cells manufactured in Examples 1-2 and Comparative Examples 3-5 were evaluated by the following charge-discharge test.

[0187] After leaving the cells at 25°C for 5 hours, they were charged at a constant current of 0.1 C until the voltage reached 5.5 V. The charged cells were then discharged at a constant current of 0.025 C until the voltage reached 3.0 V, 3.5 V, or 4.0 V, respectively.

[0188] Some of the evaluation results of the primary charge-discharge characteristics are shown in FIGS. 4A and 4B and Table 4 below.

[0189] 4A shows the voltage change depending on the specific capacity for the coin cells of Examples 1-2 and Comparative Example 1, FIG. 4B shows the discharge curves normalized by the capacity for the coin cells of Examples 1-2 and Comparative Example 1, and FIG. 4C shows the voltage change depending on the specific capacity for the coin cell of Comparative Example 4.

[0190] [Table 4]

[0191] Referring to Table 4, it was found that the average discharge voltage of the coin cells of Examples 1 and 2 was increased compared to that of Comparative Example 1. Also, referring to FIGS. 4A and 4B, the coin cells of Examples 1 and 2 exhibited superior average voltage, specific capacity, and charge / discharge characteristics compared to the coin cell of Comparative Example 1. Referring to FIG. 4C, the coin cell of Comparative Example 4 did not exhibit high-voltage discharge of 5 V or more. Furthermore, the coin cells of Comparative Examples 4 and 5 exhibited high-voltage discharge characteristics similar to that of the coin cell of Comparative Example 3.

[0192] Evaluation example 4: dQ / dV analysis The coin cells prepared in Example 1 and Comparative Examples 1 and 2 were evaluated for charge / discharge characteristics using a charger / discharger (manufacturer: TOYO, model: TOYO-3100).

[0193] The charge / discharge characteristic evaluation process will be described in more detail below.

[0194] After leaving the cells at 25°C for 5 hours, they were charged at a constant current of 0.1 C until the voltage reached 5.5 V. The charged cells were then discharged at a constant current of 0.025 C until the voltage reached 4.0 V. This charge-discharge cycle was repeated 10 times in total.

[0195] The positions of the main discharge peaks and the area ratios of the discharge curves were investigated for the dQ / dV charge / discharge differential curve distributions shown in the voltage range of 3.0 V to 5.55 V for the first cycle, and are shown in Table 5 and Figure 5. Figure 5 shows the dQ / dV discharge differential curves for the first cycle for the coin cells of Examples 1-2 and Comparative Example 1.

[0196] The discharge peak is the peak shown between 3.0 V and 5.5 V. The area ratio of the discharge curve was calculated using the following formula 2.

[0197] [Formula 2] Discharge curve area ratio = (4.7V~5.5V discharge curve area (A2) / 3.5V~5.5V discharge curve area (A1))

[0198] [Table 5]

[0199] 5 and Table 5, the coin cell of Comparative Example 1 had an electrode containing Li6Co5(P2O7)4 as the positive electrode active material, and in this case, the main discharge plateau was approximately 4.67 V. In contrast, the coin cells of Examples 1 and 2 formed a higher voltage plateau compared to the coin cell of Comparative Example 1, and the discharge amount increased in the high voltage region. In particular, the coin cell of Example 2, which had an electrode containing a positive electrode active material with a higher nickel substitution amount, formed a higher voltage plateau compared to the coin cell of Example 1, and showed a discharge plateau of 5.15 V.

[0200] Also, as shown in Table 5, the A2 / A1 ratios of the coin cells of Examples 1 and 2 were 0.434 and 0.531, respectively, and the area of ​​the high voltage discharge curve was further increased compared to the coin cell of Comparative Example 1, indicating that the discharge capacity in the high voltage region was even better.

[0201] Although one embodiment has been described above, it is not limited to this embodiment, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the accompanying drawings, and it goes without saying that these also fall within the scope of the invention.

[0202] 1 All-solid-state secondary battery 10 Positive electrode layer 11 Positive electrode current collector, positive electrode current collector layer 12 Cathode active material layer 20 negative electrode layer 21 Negative electrode current collector, negative electrode current collector layer 22 First negative electrode active material layer 23 Second negative electrode active material layer 24 Thin Film 30 Solid electrolyte layer 110 Positive electrode 111 Positive electrode current collector 112 Cathode active material layer 120 negative electrode 121 Negative electrode current collector 122 Negative electrode active material layer 130 Solid electrolyte 140 External electrode 150 Battery body 71 Positive electrode layer 72 negative electrode layer 73 Solid electrolyte layer 74 Internal current collecting layer 710 Stacked Solid-State Battery 81 Positive electrode layer 82 negative electrode layer 83 Solid electrolyte layer 84 Internal current collecting layer 810 Stacked solid-state battery stack 92 cells 94 Positive electrode active material layer 95 Negative electrode active material layer 96 Ion-conductive inorganic material layer 97 Current collector layer 98 Current collector layer 920 metal layer 923 Laminate

Claims

1. An electrode active material comprising a compound represented by the following Chemical Formula 1: [Chemical formula 1] Li ｘ (N １－ｙ My) ｚ (P ２ O ７ ) ４ In Chemical Formula 1, 5≦x≦7, 0.2≦y<1, and 4≦z≦6; M is Co, Mn, V, Ti, Cr, Cu, Sc, Y, La, Zr, Hf, Nb, Ta, Mo, W, Re, or a combination thereof.

2. 2. The electrode active material of claim 1, wherein M in Formula 1 is Co, Mn, V, Ti, Cr, Cu, Sc, or a combination thereof.

3. 2. The electrode active material according to claim 1, wherein, in Chemical Formula 1, x is a number from 5.5 to 6.5, y is a number from 0.3 to 0.9, and z is a number from 4.8 to 5.

2.

4. 4. The electrode active material according to claim 3, wherein, in Chemical Formula 1, x is 5.8 to 6.2, and z is 4.9 to 5.

1.

5. 2. The electrode active material according to claim 1, wherein the compound represented by Chemical Formula 1 is one selected from the compounds represented by the following Chemical Formulas 2 to 4: [Chemical formula 2] Li ｘ (N １－ｙ Co ｙ ) ｚ (P ２ O ７ ) ４ In Chemical Formula 2, 5≦x≦7, 0.2≦y<1, and 4≦z≦6; [Chemical formula 3] Li ｘ (N １－ｙ Mn ｙ ) ｚ (P ２ O ７ ) ４ In Chemical Formula 3, 5≦x≦7, 0.2≦y<1, and 4≦z≦6; [Chemical formula 4] Li ｘ (N １－ｙ－ａ Mn ｙ A ａ ) ｚ (P ２ O ７ ) ４ In Chemical Formula 4, 5≦x≦7, 0.2≦y<1, 4≦z≦6, 0<a≦0.2, and A is V, Nb, Ta, or a combination thereof.

6. The compound represented by the chemical formula 1 is Li ６ Ni ２ Co ３ (P ２ O ７ ) ４ Li ６ Ni ３ Co ２ (P ２ O ７ ) ４ Li ６ Ni １ Co ４ (P ２ O ７ ) ４ Li ６ Ni ４ Co １ (P ２ O ７ ) ４ Li ６ Mn ２ Ni ３ (P ２ O ７ ) ４ Li ６ Mn ２ Ni １ (P ２ O ７ ) ４ Li ６ Mn ２ V １ Ni ２ (P ２ O ７ ) ４ Li ６ Mn ２ Nb １ Ni ２ (P ２ O ７ ) ４ Li ６ Mn ２ Ta １ Ni ２ (P ２ O ７ ) ４ Li ６ Re ３ Ni ２ (P ２ O ７ ) ４ Li ６ Ni ２ V ３ (). ２ . ７ ) ４ 、i ６ i １ . ４ (). ２ . ７ ) ４ 、i ６ i ２ b ３ (). ２ . ７ ) ４ 、i ６ i １ b ４ (). ２ . ７ ) ４ 、i ６ i ２ () ３ (). ２ . ７ ) ４ 、i ６ i １ () ４ (). ２ . ７ ) ４ 、i ６ o ２ . １ i ２ (). ２ . ７ ) ４ 、i ６ o ２ . ２ i １ (). ２ . ７ ) ４ )、) ６ () ３ i ２ (). ２ . ７ )、) ６ . ３ i ２ (). ２ . ７ ) ４ 、i ６ u ３ i ２ (). ２ . ７ ) ４ 、または、! ６ 3 ３ i ２ (). ２ O ７ ) ４ The electrode active material according to claim 1 ,

7. 2. The electrode active material according to claim 1, wherein the compound of Formula 1 exhibits a main peak in a region where the diffraction angle 2θ is 28.5±2° when analyzed by X-ray diffraction using CuKα radiation.

8. 2. The electrode active material according to claim 1, wherein the ratio (P2 / P1) of the intensity of a main peak (P1) to the intensity of a minor peak (P2) determined by X-ray diffraction analysis using CuKα radiation for the compound of Chemical Formula 1 is 0.4 or less.

9. 2. The electrode active material of claim 1, wherein the compound of Chemical Formula 1 has a triclinic crystal structure and a space group (p-1).

10. 2. The electrode active material according to claim 1, wherein a dQ / dV peak voltage showing the maximum discharge curve area under the condition of a voltage of 3.0 V to 5.5 V at a current of 0.025 C in a dQ / dV charge / discharge differential curve for a battery including an electrode containing the compound of Chemical Formula 1 is 4.7 V vs. Li / Li+ or more.

11. 2. The electrode active material of claim 1, wherein in a dQ / dV charge / discharge differential curve for a battery including an electrode comprising the compound of Formula 1, the ratio (A2 / A1) of the area (A2) of the discharge curve from 4.7 V to 5.5 V to the area (A1) of the discharge curve from 3.5 V to 5.5 V under the conditions of a current of 0.025 C and a voltage of 3.0 V to 5.5 V is 0.4 or more.

12. An electrode comprising the electrode active material according to any one of claims 1 to 11.

13. A secondary battery comprising the electrode according to claim 12.

14. The secondary battery according to claim 13 , wherein the electrode in the secondary battery is a positive electrode, and the voltage of the electrode active material contained in the positive electrode is 4.8 V or more versus lithium.

15. The secondary battery according to claim 13 , wherein the secondary battery is a lithium secondary battery or an all-solid-state battery.

16. The secondary battery according to claim 15 , wherein the all-solid-state battery is a multilayer ceramic battery or a thin-film battery.

17. The multilayer ceramic battery comprises:

17. The secondary battery according to claim 16, comprising a laminate structure in which a plurality of cell units, each cell unit including a positive electrode layer including a positive electrode active material layer, a solid electrolyte layer, and a negative electrode layer including a negative electrode active material layer, are stacked such that the positive electrode active material layer and the negative electrode active material layer face each other.

18. The multilayer ceramic battery comprises:

17. The secondary battery according to claim 16, wherein the cell unit, in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are arranged in succession, comprises a stack of a plurality of cell units stacked together with the positive electrode active material layer and the negative electrode active material layer of each cell unit facing each other.

19. the secondary battery is an all-solid-state secondary battery including a positive electrode layer including a positive electrode active material layer, a negative electrode layer including a first negative electrode active material layer or a third negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; 14. The secondary battery of claim 13, wherein the positive electrode active material layer comprises a positive electrode active material comprising a compound represented by the following Chemical Formula 1: [Chemical formula 1] Li ｘ (N １－ｙ M ｙ ) ｚ (P ２ O ７ ) ４ In Chemical Formula 1, 5≦x≦7, 0.2≦y<1, 4≦z≦6, M is Co, Mn, V, Ti, Cr, Cu, Sc, Y, La, Zr, Hf, Nb, Ta, Mo, W, Re, or a combination thereof.

20. The secondary battery of claim 19 , wherein the first negative electrode active material layer comprises at least one selected from the group consisting of a carbon-based negative electrode active material and a metal or semi-metal negative electrode active material.

21. The carbon-based negative electrode active material includes at least one selected from amorphous carbon and crystalline carbon, 21. The secondary battery of claim 20, wherein the metal or semimetal negative electrode active material comprises one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

22. The secondary battery further includes a negative electrode current collector, a second negative electrode active material layer disposed between the negative electrode current collector and the first negative electrode active material layer, and / or between the solid electrolyte layer and the first negative electrode active material layer; The secondary battery of claim 19 , wherein the second negative electrode active material layer is a metal layer containing lithium or a lithium alloy.

23. 20. The secondary battery according to claim 19, wherein the third negative electrode active material layer is a metal layer containing lithium or a lithium alloy.

24. mixing a nickel precursor, a lithium precursor, a phosphorus precursor, and an M precursor to obtain a precursor mixture; and heat-treating the precursor mixture. [Chemical formula 1] Li ｘ (N １－ｙ M ｙ ) ｚ (P ２ O ７ ) ４ In Chemical Formula 1, 5≦x≦7, 0.2≦y<1, 4≦z≦6, M is Co, Mn, V, Ti, Cr, Cu, Sc, Y, La, Zr, Hf, Nb, Ta, Mo, W, Re, or a combination thereof.

25. The method for producing an electrode active material according to claim 24, wherein the heat treatment is carried out at 500°C to 1000°C.

26. 25. The method of claim 24, wherein the mixing is performed by mechanical milling.

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