WO2018038529A1 - Test cell with high reliability in electrode property test - Google Patents

Abstract

The present invention relates to a test cell for measuring electrode properties, in which an electrode assembly comprising a first reference electrode, a second reference electrode, and a first electrode subject to property measurement is stored and sealed alongside an electrolyte in a pouch-type cell case of a laminate sheet.

Description

Highly reliable test cell for electrode characteristic testing

The present invention relates to a test cell with high reliability for electrode characteristic testing.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, many researches on secondary battery cells capable of meeting various needs have been conducted.

In particular, there is a high demand for lithium secondary battery cells such as lithium ion batteries, lithium ion polymer batteries, etc., which have advantages such as high energy density, discharge voltage, and output stability.

On the other hand, for the development of new battery cells, to confirm the performance of the manufactured battery cells, etc., the potential, output, and capacity of the electrode are measured. This may be done in the development stage of the electrode or for quality discrimination of the mass produced electrode.

In general, the performance test of the electrode is a coin cell (combination) of a combination of the pure lithium electrode and the electrode to be measured, which is already known characteristics, such as electrode potential or electrode resistance to enable accurate characteristics measurement After manufacturing, while repeatedly charging and discharging, the life characteristics, output characteristics and capacitance characteristics of the electrode are measured.

However, even in such a test, due to the following problems, as the charge and discharge is repeated, there is a disadvantage that the reliability of the measured value is lowered.

First, as charging and discharging are repeated, the reversibility of the lithium electrode is lowered and an error occurs in the measured electrode characteristics.

Second, the can-type battery case used in manufacturing a coin cell has a high resistance, and thus, it is difficult to confirm precise output characteristics.

Therefore, there is a high need for a technique capable of measuring highly reliable electrode characteristics.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

Specifically, the object of the present invention, unlike the conventional coin cell, it is possible to minimize the error of the measurement of the electrode characteristics by using a second reference electrode that can measure the characteristic change of the lithium electrode, while allowing accurate output characteristics of low resistance. To provide a test cell that can.

The test cell of the present invention for achieving the above object is a test cell for measuring the electrode characteristics, the electrode assembly including a first reference electrode, a second reference electrode, and a first electrode to be measured characteristics, It is sealed with the electrolyte solution in the state accommodated in the pouch type battery case of a laminate sheet.

That is, the test cell according to the present invention, instead of the can type battery case having a high resistance, the battery case is composed of a laminate sheet having a relatively low contact resistance, so that the resistance due to the battery case compared to the conventional coin cell is more accurate output You can check the characteristics.

In addition, the test cell has a double check system for confirming electrode characteristics with the first reference electrode and the second reference electrode, and as described below, there is an advantage in that an error is significantly low in measuring the characteristics of the electrode.

In one specific example, a test cell according to the present invention measures an output characteristic and a capacitance characteristic of a first electrode by an electrochemical reaction between the first reference electrode and the first electrode;

As the second reference electrode, changes in electrochemical properties of the first reference electrode and the first electrode can be confirmed.

That is, the test cell of the present invention checks the change of the electrochemical characteristics of the first reference electrode and the first electrode through the second reference electrode, and double checks to confirm the electrochemical characteristics of the first electrode through the first reference electrode. As a system, it is possible to predict errors and errors in output characteristics and capacitance characteristics of the first electrode by reflecting the change in real time as the general characteristics of the first reference electrode according to the change of the electrochemical characteristics of the first reference electrode. Can be.

At this time, the electrochemical reaction between the second reference electrode and the first electrode is negligible, so it is necessary to largely reflect the change in the electrochemical characteristics of the second reference electrode in determining the characteristics of the first reference electrode or the first electrode. It may not be.

As described above, regardless of the characteristic change of the first reference electrode, it is possible to more accurately identify the first electrode characteristics in a state where the number of cycles is high, so that the test cell of the present invention can provide highly reliable measured values. It can be.

This is significant in that the life characteristics and the capacitance characteristics of only the electrode to be measured can be accurately confirmed, even though the performance of the test cell itself is degraded at a high cycle.

In the present invention, the first reference electrode is a lithium electrode made of pure lithium, the pure lithium can form a plate-shaped electrode.

The second reference electrode has a structure in which an electrode active material is coated on a main body of a wire structure made of copper (Cu) or aluminum (Al);

The test cell may have a structure in which the battery case is sealed while a part of the wire of the second reference electrode is led out of the battery case.

That is, in the test cell according to the present invention, since the second reference electrode is disposed between the first reference electrode and the first electrode, not only the relative potential with respect to each of the first reference electrode and the second reference electrode can be measured, By measuring the relative potential with respect to the first reference electrode at the location where the actual electrochemical reaction occurs, it is possible to precisely check the change in the electrochemical properties of the first reference electrode.

In addition, since the second reference electrode is disposed between the first reference electrode and the first electrode in a small wire structure, there is little increase in the overall volume of the battery cell due to the second reference electrode, and the surface area is also small. It has the advantage of low contact resistance.

In addition, the second reference electrode has a wire structure extending from the inside of the test cell to the outside, and the user can easily measure the relative potential by connecting a potential measuring device to the second reference electrode on the outside. You can also use the test cell with the wire cut.

The electrode active material constituting the second reference electrode should be a stable material having low reactivity with the electrolyte and not interfering with the reversibility of lithium ions, and having a constant voltage range in a wide capacitance range for use as a reference electrode. The material is not particularly limited, but in detail, the material may be lithium titanium oxide (LTO) having high structural stability and slow electrode degradation.

In the present invention, the first reference electrode serves as a cathode for the first electrode and the second reference electrode, and the second reference electrode serves as a reference electrode for the first reference electrode and the first electrode. do. In other words, in the test cell of the present invention, the first electrode acts only as an anode, and the second reference electrode acts as a reference electrode for the first reference electrode and the first electrode. However, the electrochemical reaction of the second reference electrode in the test cell is negligible and may hardly affect the capacity or the life of the actual test cell.

The second reference electrode may measure a relative potential with respect to each of the first electrode and the first reference electrode in the test cell.

In one specific example, the electrode assembly may have a structure in which the first reference electrode, the first separator, the second reference electrode, the second separator and the first electrode are sequentially stacked.

The present invention also provides a method for measuring the characteristics of the first electrode using the test cell,

(i) measuring output and capacity characteristics of the test cell at intervals of 10 cycles to 100 cycles while repeatedly charging and discharging the test cells;

(ii) further measuring an electrode potential change of the first reference electrode based on the second reference electrode during the measurement of step (i); And

(iii) correcting a measurement value of the output and capacitance characteristics of the step (i) based on the change of the electrode potential of the first reference electrode.

That is, in the method according to the present invention, the change of the electrochemical characteristics of the first reference electrode and the first electrode through the second reference electrode, and the double check of the electrochemical characteristics of the first electrode through the first reference electrode It is composed of a check system, according to the change in the electrochemical characteristics of the first reference electrode, and reflects the change in real time as the overall characteristics of the first reference electrode to the error and error of the output characteristics and capacitance characteristics of the first electrode It can be predicted.

As a result, the method of the present invention can more accurately confirm the first electrode characteristics, regardless of the number of cycles, and more accurately measure the electrode characteristics of the first electrode.

The internal resistance of the test cell may be 0.5Ω to 5Ω.

This has a resistance of approximately 10 to 100 times lower than that of a coin cell made of a can type battery case, and based on this characteristic, it is possible to more accurately identify output characteristics of an electrode.

In the test cell of the present invention, the first electrode may be an electrode for forming a positive electrode or a negative electrode of a lithium secondary battery.

In one specific example, the first electrode is prepared by applying a mixture of a positive electrode active material, a conductive material, and a binder to a positive electrode current collector, followed by drying, and optionally, a filler is further added to the mixture.

The positive electrode current collector is generally made to a thickness of 3 to 500 micrometers. The positive electrode current collector and the extension current collector are not particularly limited as long as they have high conductivity without causing chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum Surface treated with carbon, nickel, titanium, silver or the like on the surface of the stainless steel may be used. The positive electrode current collector and the extension current collector may form fine irregularities on the surface thereof to increase adhesion of the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ and the like; Ni-site type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3; Formula LiMn _{2 - x} M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like, but are not limited to these.

The conductive material is typically added in an amount of 1 to 30 wt% based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists the bonding of the active material and the conductive material to the current collector, and is generally added in an amount of 1 to 30 wt% based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for inhibiting expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery. Examples of the filler include olefinic polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.

In another specific example, the first electrode is manufactured by coating and drying a negative electrode active material on a negative electrode current collector, and optionally, the components as described above may be further included as necessary.

The negative electrode current collector is generally made to a thickness of 3 to 500 micrometers. Such a negative electrode current collector and / or an extension current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, Surface treated with carbon, nickel, titanium, silver, or the like on the surface of copper or stainless steel, aluminum-cadmium alloy, and the like can be used. In addition, like the positive electrode current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

As said negative electrode active material, For example, carbon, such as hardly graphitized carbon and graphite type carbon; Li _x Fe ₂ O ₃ (0≤≤x≤≤1), Li _x WO ₂ (0≤≤x≤≤1), Sn _x Me _{1 - x} Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me ': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 <x≤≤1;1≤≤y≤≤3; 1≤≤z≤≤8) Metal complex oxides such as these; Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , and metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

In the present invention, the separator is interposed between the anode and the cathode, an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally from 0.01 to 10 micrometers, the thickness is generally from 5 to 300 micrometers. Such a separator, in addition to the SRS (Safety-Reinforcing Separators) separator of the organic / inorganic composite porous described above; For example, olefin polymers, such as polypropylene of chemical resistance and hydrophobicity; Sheets or non-woven fabrics made of glass fibers or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The electrolyte may be a lithium salt-containing non-aqueous electrolyte, and consists of a non-aqueous electrolyte and a lithium salt. As the nonaqueous electrolyte, nonaqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like are used, but not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and gamma Butyl lactone, 1,2-dimethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxorone, formamide, dimethylformamide, dioxolon , Acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxy methane, dioxorone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbo Aprotic organic solvents such as nate derivatives, tetrahydrofuran derivatives, ethers, methyl pyroionate and ethyl propionate can be used.

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyedgetion lysine, polyester sulfides, polyvinyl alcohols, polyvinylidene fluorides, Polymers containing ionic dissociating groups and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, sulfates and the like of Li, such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , and the like, may be used.

The lithium salt is a good material to be dissolved in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

In addition, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, Nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride and the like may be added. have. In some cases, in order to impart nonflammability, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high temperature storage characteristics, and FEC (Fluoro-Ethylene) may be further included. Carbonate), PRS (Propene sultone) may be further included.

In one specific example, lithium salts such as LiPF ₆ , LiClO ₄ , LiBF ₄ , LiN (SO ₂ CF ₃ ) _2, and the like, may be prepared by cyclic carbonate of EC or PC, which is a highly dielectric solvent, and DEC, DMC, or EMC, which are low viscosity solvents. Lithium salt-containing non-aqueous electrolytes can be prepared by adding them to a mixed solvent of linear carbonates.

As described above, in the test cell according to the present invention, instead of the can type battery case having a high resistance, the battery case is composed of a laminate sheet having a relatively low contact resistance. Lower accuracy allows for more accurate output characteristics.

In addition, the test cell has a double check system that checks electrode characteristics with the first reference electrode and the second reference electrode, and has an advantage that the error is significantly low in measuring the characteristics of the electrode.

1 is a schematic diagram based on a vertical section of a test cell according to one embodiment of the present invention;

2 is a schematic diagram of the top of a test cell;

3 is a schematic diagram of a second reference electrode;

4 is a flowchart of a test cell using method according to an embodiment of the present invention.

Hereinafter, although described with reference to the drawings according to an embodiment of the present invention, this is for easier understanding of the present invention, the scope of the present invention is not limited thereto.

FIG. 1 is a schematic diagram based on a vertical cross section of a test cell according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of an upper portion of a test cell. 3 shows a schematic diagram of the second reference electrode.

Referring to these drawings, the test cell 100 includes a first reference electrode 110 made of pure lithium, a second reference electrode 120 including an LTO electrode active material, and a first electrode to be measured. The electrode assembly including 102 is sealed together with the electrolyte in a state of being housed in the pouch type battery case 104 of the laminate sheet.

That is, in the test cell 100 according to the present invention, instead of the can type battery case 104 having a high resistance, the battery case 104 is formed of a laminate sheet having a relatively low contact resistance. The resistance due to the case 104 is low. This allows for more accurate measurements when checking the output characteristics.

The electrode assembly has a structure in which the first reference electrode 110, the first separator, the second reference electrode 120, the second separator and the first electrode 102 are sequentially stacked.

The second reference electrode 120 is a structure in which an electrode active material 124 is coated on a main body 122 of a wire structure made of copper (Cu), and the test cell 100 includes a second reference electrode 120. A portion of the main body 122 of the wire structure of) may be a structure in which the battery case 104 is sealed in a state in which a part of the main body 122 is led out of the battery case 104.

Therefore, since the second reference electrode 120 is disposed between the first reference electrode 110 and the first electrode 102, relative potentials to the first reference electrode 110 and the second reference electrode 120, respectively. Not only can be measured, it is possible to accurately determine the change in the electrochemical properties of the first reference electrode 110 by measuring the relative potential with respect to the first reference electrode 110 at the location where the actual electrochemical reaction occurs.

In addition, the second reference electrode 120 is a wire structure extending from the inside of the test cell 100 to the outside, and the user can easily measure the relative potential by connecting a potential measuring device to the second reference electrode 120 on the outside. Can be. In some cases, the test cell 100 may be used while cutting the extended wire.

In the test cell 100, the first reference electrode 110 acts as a cathode for the first electrode 102 and the second reference electrode 120, and the second reference electrode 120 serves as the first reference electrode. It acts as a reference electrode for the 110 and the first electrode 102.

Here, the test cell 100 may measure the output characteristics and the capacitance characteristics of the first electrode 102 by an electrochemical reaction between the first reference electrode 110 and the first electrode 102, and the second reference electrode ( 120, a change in electrochemical properties of the first reference electrode 110 can be confirmed.

That is, the test cell 100 of the present invention checks the change in the electrochemical characteristics of the first reference electrode 110 through the second reference electrode 120, and the first electrode (1) through the first reference electrode 110. It consists of a double check system to confirm the electrochemical properties of 102.

However, the electrochemical reaction between the second reference electrode 120 and the first electrode 102 in the test cell 100 may be negligible.

Meanwhile, FIG. 4 provides a method of measuring characteristics of the first electrode 102 using the test cell 100. Referring to FIG. 4 together with FIGS. 1 to 3, in step 210, the first reference electrode 110, the first separator, the second reference electrode 120, the second separator and the first electrode 102 are formed. After the electrode assemblies having the sequentially stacked structure are accommodated together with the electrolyte in the pouch-type battery case 104, the battery case 104 is sealed to prepare a test cell 100.

The pouch type battery case may use a laminate sheet. The laminate sheet may have a multi-layered structure and may consist of an outermost outer coating layer, a metal layer that prevents penetration of material, and an inner sealant layer for sealing.

The inner sealant layer is thermally fused to each other by applied heat and pressure in a state in which the electrode assembly is embedded, and serves to provide a sealability, and mainly consists of CPP (non-stretched polypropylene film).

The metal layer may be aluminum (Al) to exhibit a function of preventing the inflow or leakage of foreign matter. The metal layer may have a structure in which a chromium oxide film is formed on a surface thereof, and the film serves to prevent oxidation and corrosion of the metal layer by forming an oxide film in air by combining chromium contained in the metal layer with oxygen. Specifically, the chromium oxide film may be made of chromium trivalent oxide (Cr ₂ O ₃ ).

In one specific example, the thickness of the laminate sheet may be 70 μm to 150 μm, specifically 80 μm to 140 μm, and more specifically 100 μm to 130 μm. The thickness of the laminate sheet is a thickness including all of the thicknesses of the resin layer, at least one metal layer, and the sealant layer. When the thickness of the laminate sheet is smaller than 70 μm, the thickness of the metal layer is also reduced in proportion to protect the battery cell from external shock. It may be difficult, and if it is larger than 150 ㎛ because the weight and volume of the entire secondary battery is increased, there is a problem that can be limited device applied is not preferable.

In one specific example, the laminate sheet may be configured to include one metal layer, in this case, the thickness of the metal layer may be formed from 10 ㎛ to 100 ㎛ within the range of the thickness of the laminate sheet described above And in detail, it may be formed of 15 ㎛ to 80 ㎛. When the thickness of the metal layer is thinner than 10 mu m, it is difficult to exert an effect of improving mechanical strength. When the thickness of the metal layer is thicker than 100 mu m, the thickness of the laminate sheet increases, which makes it difficult to provide a compact secondary battery.

In another specific example, the laminate sheet may be a composition including two metal layers. As such, when two metal layers are included, in order to prevent the thickness of the entire laminate sheet from increasing, it is preferable to use a thin metal layer as compared with the case where the metal layer has a thickness of 20 μm to 20 μm. It may be formed to 50 ㎛, in detail may be formed from 25 ㎛ to 40 ㎛.

On the other hand, between the metal layer and between the metal layer and the sealant layer further includes an adhesive layer for increasing the bonding force between the layers made of different materials, the adhesive layer is epoxy, phenolic, melamine, polyimide, polyester-based It may be made of one or more selected from the group consisting of urethane-based, polyethylene terephthalate-based and polyether urethane-based materials.

Thereafter, the charging and discharging of the test cell 100 is repeatedly performed in step 220, and when an arbitrary cycle in which the charging and discharging cycle is selected from 10 to 100 is completed, the process 230 is performed.

In operation 230, an operation 230a of measuring output and capacitance characteristics of the test cell 100 and an electrode potential change of the first reference electrode 110 are measured 230b.

The order of execution of steps 230a and 230b is irrelevant and may be performed simultaneously.

The characteristic of the test cell 100 measured in the process 230a may be assumed to be the characteristic of the first electrode 102, which indicates a state in which the overall performance of the first reference electrode 110 made of pure lithium is recognized in advance. On the premise.

In operation 230b, the change of the electrode potential of the first reference electrode 110 is further measured based on the second reference electrode 120 to measure the electrochemical change of the first reference electrode 110.

In this state, the process 240 proceeds to correct the measured value of the process 230a based on the change of the electrode potential of the first reference electrode 110, thereby adjusting the first value based on the electrochemical change of the first reference electrode 110. Errors and errors in the output characteristics and the capacitance characteristics of the electrode 102 are predicted and reflected.

Therefore, in operation 250, the characteristic of the first electrode 102 may be determined based on the corrected data.

After such a series of processes, when the charging and discharging cycle is selected from 10 to 100 while completing the process 220, the process 230 to 250 may be sequentially performed to sequentially perform the first cycle according to the cycle. The reduction of the output characteristic and the capacitance characteristic of the electrode 102 is measured precisely.

The present invention will be described in more detail with reference to the following examples. However, the following Examples and Experimental Examples are for illustrating the present invention and the scope of the present invention is not limited by these Examples and Experimental Examples.

Example

<Production of First Reference Electrode>

Plate-shaped pure lithium metal was prepared as a first reference electrode.

<Production of Second Reference Electrode>

90% by weight of Li ₄ Ti ₅ O _{12, 4} % by weight Denka black (conductor) and 6% by weight PVDF (polyvinylidene fluoride, binder) were added to N-Methyl-2-Pyrrolidone (NMP). The cathode mixture slurry prepared by coating was coated on a wire structure made of copper to prepare a second reference electrode.

<Production of First Electrode>

96% by weight of LiNiCoMnO ₂ , ₂ % by weight Denka black (conductive material) and 2% by weight PVDF (polyvinylidene fluoride, binder) were added to N-Methyl-2-Pyrrolidone (NMP) to slurry the cathode mixture. Was prepared. The prepared positive electrode mixture slurry was coated on one surface of an aluminum current collector to a thickness of 100 μm, dried and rolled, and then punched to a predetermined size to prepare a first electrode.

Fabrication of Triode Test Cell

Ethylene carbonate in the electrode assembly having a structure in which the first reference electrode, the first separator (polypropylene-based porous membrane), the second reference electrode, the second separator (polypropylene-based porous membrane), and the first electrode are sequentially stacked (EC) and an electrolyte solution in which 1M lithium hexafluorophosphate (LiPF ₆ ) was dissolved were injected into a solvent in which ethyl methyl carbonate (DEC) was mixed at a volume ratio of 50:50. Thereafter, the battery cell was sealed in a pouch-type battery case of a laminate sheet, and a test cell was manufactured by sealing the battery case.

Comparative example

96% by weight of LiNiCoMnO ₂ , ₂ % by weight Denka black (conductive material) and 2% by weight PVDF (polyvinylidene fluoride, binder) were added to N-Methyl-2-Pyrrolidone (NMP) to slurry the cathode mixture. Was prepared. The prepared positive electrode mixture slurry was coated on one surface of an aluminum current collector to a thickness of 100 μm, dried and rolled, and then punched to a predetermined size to prepare an electrode. As the counter electrode, a plate-shaped pure lithium metal was prepared. The electrode assembly obtained by sequentially stacking the prepared electrode, the separator (polypropylene-based porous membrane), and the prepared counter electrode was accommodated in a can-type battery case to manufacture a test cell.

Experimental Example 1 Dose retention rate and dose retention rate deviation

For the test cells prepared in Examples and Comparative Examples, the charge and discharge rate characteristics were measured in a condition of 0.5C / 2C within a range of 3 to 4.2V driving voltage at room temperature (25 ° C) and are shown in Table 1. Deviation calculations calculated standard deviations for five cells.

Experimental Example 2 EIS Resistance and Resistance Deviation

The interfacial resistance of SOC50 was measured by EIS, and the results are shown in Table 1, and the resistance deviation was calculated and shown in Table 1. Deviation calculations calculated standard deviations for five cells.

	2C discharge capacity retention rate (%)	Capacity maintenance rate deviation	EIS resistance (ohmcm2)	Resistance deviation
Example	90	0.36	3.3	0.5
Comparative example	85	5	14.9	11

As can be seen from the above results, the test cell of the embodiment has much smaller capacity retention variation and resistance variation than the test cell of the comparative example, and thus it can be confirmed that the reliability of the electrode characteristic test is high.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (13)

1. As a test cell for measuring electrode characteristics, an electrode assembly including a first reference electrode, a second reference electrode, and a first electrode to be measured is stored together with an electrolyte in a pouch-type battery case of a laminate sheet. And the test cell is sealed in a closed state.
2. The method of claim 1,

   Measuring an output characteristic and a capacitance characteristic of the first electrode by an electrochemical reaction between the first reference electrode and the first electrode;

   The test cell, characterized in that for confirming the change in the electrochemical characteristics of the first reference electrode as the second reference electrode.
3. The test cell of claim 2, wherein an error and an error of an output characteristic and a capacitance characteristic of the first electrode are predicted according to a change in the electrochemical characteristic of the first reference electrode.
4. The test cell according to claim 2, wherein the first reference electrode is a lithium electrode made of pure lithium, and the pure lithium forms a plate-shaped electrode.
5. The method of claim 2,

   The second reference electrode has a structure in which an electrode active material is coated on a main body of a wire structure made of copper (Cu) or aluminum (Al);

   The test cell is a test cell, characterized in that the structure of the battery case is sealed, a part of the wire of the second reference electrode is led to the outside of the battery case.
6. The test cell of claim 5, wherein the electrode active material is lithium titanium oxide (LTO).
7. The test cell of claim 2, wherein the first reference electrode serves as a cathode for the first electrode and the second reference electrode.
8. The test cell of claim 2, wherein the second reference electrode serves as a reference electrode with respect to the first reference electrode and the first electrode.
9. The test cell of claim 2, wherein the second reference electrode measures a relative potential with respect to each of the first electrode and the first reference electrode.
10. The test cell of claim 1, wherein the electrode assembly has a structure in which a first reference electrode, a first separator, a second reference electrode, a second separator, and a first electrode are sequentially stacked.
11. A method for measuring the characteristics of a first electrode using a test cell according to any one of claims 1 to 10,

    (i) measuring output and capacity characteristics of the test cell at intervals of 10 cycles to 100 cycles while repeatedly charging and discharging the test cells;

    (ii) further measuring an electrode potential change of the first reference electrode based on the second reference electrode during the measurement of step (i); And

    (iii) correcting a measurement value of the output and capacitance characteristics in the step (i) based on the change of the electrode potential of the first reference electrode;

    Method comprising a.
12. 12. The method of claim 11, wherein the method further comprises measuring internal resistance of the test cell using electrochemical impedance spectroscopy.
13. The method of claim 12, wherein the internal resistance of the test cell is 0.5Ω to 5Ω.

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