JP2012079582A - Secondary battery, method for measuring resistance of positive electrode or negative electrode of secondary battery, and method for diagnosing degree of deterioration in positive electrode or negative electrode of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery in which each resistance of a positive electrode and a negative electrode can be measured individually and highly precisely, so that the degree of deterioration can be diagnosed easily and highly precisely.SOLUTION: The secondary batty comprises: a positive electrode 101; a negative electrode 102; and an electrolyte-containing phase. The positive electrode 101 and the negative electrode 102 transfer charges via the electrolyte-containing phase, so that the secondary battery can be charged and discharged. The secondary batty further comprises: a reference electrode 103; and a counter electrode 104, while the reference electrode 103 and the counter electrode 104 are electrically connected with each other via the electrolyte-containing phase, and also are electrically connected to the positive electrode 101 and a negative electrode 102 via the electrolyte-containing phase.

Description

  The present invention relates to a secondary battery, a resistance measurement method for a positive electrode or a negative electrode of a secondary battery, and a diagnostic method for a degree of deterioration of a positive electrode or a negative electrode of a secondary battery.

  In recent years, secondary batteries tend to be used for a long time, as typified by secondary batteries for electric vehicles and household secondary batteries. Secondary batteries deteriorate with long-term use. For this reason, it is required that the degree of deterioration of the secondary battery can be diagnosed easily and accurately.

  In Patent Document 1, a charge current pulse or a discharge current pulse is applied to a secondary battery, and a resistance (internal resistance) is calculated from an input current and a response voltage after a predetermined frequency has elapsed, thereby diagnosing deterioration and continuing. There has been proposed a method for determining whether or not it can be used.

  Patent Document 2 proposes a four-pole electrochemical cell having a reference electrode in the vicinity of each of a positive electrode (working electrode) and a negative electrode (counter electrode). In this electrochemical cell, the potential of the positive electrode (working electrode) alone and the potential of the negative electrode (counter electrode) alone can be grasped more accurately, and the potential gradient generated between the positive electrode (working electrode) and the negative electrode (counter electrode) I can grasp it.

JP 2010-156702 A JP 2006-179329 A

  In the deterioration degree diagnosis method of Patent Document 1, since the resistance (internal resistance) of each of the positive electrode and the negative electrode cannot be measured individually, it is impossible to examine how much the positive electrode or the negative electrode has deteriorated, and the accuracy. Can not make a good diagnosis.

  On the other hand, according to the electrochemical cell of Patent Document 2, as described above, the potentials of the positive electrode and the negative electrode can be measured individually and accurately. However, when the resistance of the counter electrode (negative electrode) is larger than that of the working electrode (positive electrode), the electrode reaction is rate-controlled at the counter electrode when measuring the AC impedance of the working electrode (sometimes referred to as internal impedance or simply impedance). Therefore, the resistance of the working electrode cannot be measured with high accuracy.

  As described above, since the conventional secondary battery or the secondary battery deterioration degree diagnosis method cannot measure the resistances of the positive electrode and the negative electrode individually and accurately, the degree of deterioration of the secondary battery. Cannot be diagnosed accurately.

  Therefore, the present invention can measure the resistance of each of the positive electrode and the negative electrode individually and accurately, and can measure the degree of deterioration easily and accurately, and the resistance measurement of the positive electrode or the negative electrode of the secondary battery. It is an object to provide a method and a method for diagnosing the degree of deterioration of a positive electrode or a negative electrode of a secondary battery.

In order to achieve the above object, the secondary battery of the present invention comprises:
Including a positive electrode, a negative electrode and an electrolyte-containing phase,
The positive electrode and the negative electrode can be charged and discharged by transferring charge through the electrolyte-containing phase,
Furthermore, including a reference electrode and a counter electrode,
The reference electrode and the counter electrode are electrically connected to each other via the electrolyte-containing phase, and are electrically connected to the positive electrode and the negative electrode via the electrolyte-containing phase.

According to the present invention, a method for measuring resistance of a positive electrode or a negative electrode of a secondary battery is as follows:
AC impedance measurement step of measuring the AC impedance of the positive electrode or the negative electrode using the positive electrode or the negative electrode as a working electrode, and further using the reference electrode and the counter electrode;
The method of measuring resistance of the positive electrode or the negative electrode of the secondary battery of the present invention, comprising a resistance calculating step of calculating the resistance of the positive electrode or the negative electrode based on the AC impedance.

According to the present invention, a method for diagnosing the degree of deterioration of a positive electrode or negative electrode of a secondary battery is as follows:
A resistance measuring step of measuring the resistance of the positive electrode or the negative electrode after performing at least one of charging and discharging for a predetermined time and a predetermined number of times on the secondary battery of the present invention by the measuring method of the present invention; ,
Deterioration degree diagnosis step of diagnosing the degree of deterioration of the positive electrode or the negative electrode by comparing the resistance of the positive electrode or the negative electrode measured in the resistance measurement step with the resistance before performing at least one of the charging and discharging. It is characterized by including.

  According to the secondary battery, the method for measuring the resistance of the positive electrode or the negative electrode of the secondary battery, and the method for diagnosing the deterioration degree of the positive electrode or the negative electrode of the secondary battery, the resistance of each of the positive electrode and the negative electrode is individually and accurately It can be measured well and the degree of deterioration can be diagnosed easily and accurately.

It is a perspective view which shows the structure of an example of the secondary battery in this invention. FIG. 2 is an exploded perspective view of the secondary battery of FIG. 1. 3 is a graph illustrating AC impedance measurement results in the secondary batteries of Examples 1 and 2. FIG. 3A is a Nyquist diagram. FIG. 3B is a Bode diagram. 4 is a graph illustrating an AC impedance measurement result of a positive electrode and a negative electrode in the secondary battery of Example 1. FIG. 4A is a Nyquist diagram. FIG. 4B is a Bode diagram.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited by the following description. In the present invention, the “resistance” of each electrode (positive electrode, negative electrode, working electrode or counter electrode) of the secondary battery is sometimes referred to as “internal resistance”, “electric resistance” or “charge transfer resistance”. However, all are synonymous.

[Secondary battery]
1 and 2 schematically show an example of the structure of the secondary battery of the present invention. FIG. 1 is a perspective view, and FIG. 2 is an exploded perspective view.

  As shown in FIG. 1, in the secondary battery 110 of this example, each component (not shown in the figure) is sealed by an exterior body 109, and four electrodes are formed from the end of the exterior body 109. The lead 106 protrudes. Each of the constituent elements sealed in the outer package 109 includes a positive electrode, a negative electrode, a reference electrode, a counter electrode, and an electrolyte-containing phase. The positive electrode and the negative electrode can be charged and discharged by transferring charge through the electrolyte-containing phase. The reference electrode and the counter electrode are electrically connected to each other via the electrolyte-containing phase, and are electrically connected to the positive electrode and the negative electrode via the electrolyte-containing phase.

  As shown in FIG. 2, the secondary battery 110 of this example includes three current collectors 105, and the positive electrode 101, the negative electrode 102, and the counter electrode 104 are each formed on individual current collectors 105. . The reference electrode 103 is formed on the reference electrode current collector 111. Three of the four electrode leads 106 are connected to the current collector 105 for the positive electrode 101, the negative electrode 102, or the counter electrode 104, respectively, and the remaining one is connected to the reference electrode current collector 111. ing. Further, the secondary battery 110 includes two separators 107 and one counter electrode separator 108. Each separator 107 and counter electrode separator 108 are porous, and each includes an electrolyte-containing phase (not shown) in the pores.

  The positive electrode 101 formed on the current collector 105 having the electrode lead 106 and the negative electrode 102 formed on the current collector 105 having the electrode lead 106 sandwich one of the two separators 107. Are superimposed so that they face each other. The reference electrode 103 formed on the current collector 111 having the electrode lead 106 is disposed on the opposite side of the positive electrode 1 with the negative electrode 102 interposed therebetween, and another separator 107 is interposed between the negative electrode 102 and the reference electrode 103. The anode 102 is overlapped with the anode 102. The counter electrode 104 formed on the current collector 105 having the electrode lead 106 is disposed on the opposite side of the negative electrode 102 with the reference electrode 103 interposed therebetween, and the counter electrode separator 108 is interposed between the counter electrode 103 and the reference electrode 103. Thus, it is superimposed on the reference electrode 103. These laminated bodies are sealed with two exterior bodies 109 to form a secondary battery 110.

  Although the formation material of each component which comprises the secondary battery 110, a structure, etc. are not specifically limited, For example, it is as follows.

The positive electrode 101 includes, for example, a positive electrode active material, a conductivity imparting agent, and an adhesive. As the positive electrode active material, a metal oxide, an organic radical compound, a disulfide compound, or the like can be used. Examples of the metal oxide include lithium manganate such as LiMnO ₂ and Li _x Mn ₂ O ₄ (0 <x <2) or lithium manganate having a spinel structure, MnO ₂ , LiCoO ₂ , LiNiO ₂ , Li _y. V ₂ O ₅ (0 <y <2), olivine-based material LiFePO ₄ , materials obtained by substituting a part of Mn in the spinel structure with other transition metals LiNi _0.5 Mn _1.5 O ₄ , LiCr _0.5 Mn _1.5 O ₄ , LiCo _0.5 Mn _1.5 O ₄ , LiCoMnO ₄ , LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.33 Mn _0.33 Co _0.33 O ₂ , LiNi _{0. 8} Co _0.2 O ₂ , LiN _0.5 Mn _1.5-z Ti _z O ₄ (0 <z <1.5), and the like. The organic radical compound has an N-oxo-ammonium cation partial structure represented by the formula (1) in the following reaction formula (A) in the oxidized state, and the formula in the following reaction formula (A) in the reduced state. Examples thereof include a nitroxyl compound having a nitroxyl radical partial structure represented by (2). Examples of the disulfide compound include dithioglycol, 2,5-dimercapto-1,3,4-thiadiazole, S-triazine-2,4,6-trithiol and the like. These positive electrode active materials may be used alone or in combination of two or more.

  Examples of the material for the conductivity imparting agent include carbonaceous fine particles such as graphite, carbon black, and acetylene black, carbon fibers such as carbon nanotubes, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene. .

  Examples of the adhesive include polytetrafluoroethylene (PTFE), polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene / butadiene copolymer rubber, and polypropylene. , Resin binders such as polyethylene, polyimide, partially carboxylated cellulose, and various polyurethanes.

  The negative electrode 102 includes, for example, a negative electrode active material, a conductivity imparting agent, and an adhesive. As the negative electrode active material, lithium metal, lithium alloy, graphite or the like can be used. These shapes are not particularly limited, and may be, for example, a thin film, a powdered product, a fiber, or a flake. Moreover, these negative electrode active materials may be used independently and may be used together 2 or more types.

  As the reference electrode 103, lithium metal or the like can be used. A method for manufacturing the reference electrode 103 using lithium metal is not particularly limited, and examples thereof include pressure bonding, pasting, electrodeposition, or coating of lithium metal on a part of the surface of the reference electrode current collector 111.

  Although the forming material of the counter electrode 104 is not specifically limited, A carbon material, lithium metal, platinum, etc. are mentioned, A carbon material is preferable. Since the carbon material has a large specific surface area, the specific resistance is small and the projected area of the counter electrode can be reduced. Examples of the carbon material include graphite and activated carbon, and activated carbon is particularly preferable. Activated carbon has a large specific surface area among carbon materials, so that the specific resistance is further reduced and the projected area of the counter electrode can be further reduced. The specific resistance of the counter electrode 104 is preferably 200 Ω · cm or less, more preferably 100 Ω · cm or less, and particularly preferably 50 Ω · cm or less. Although the minimum of the specific resistance of the counter electrode 104 is not specifically limited, For example, it is a value exceeding 0 Ω · cm.

  As the current collector 105, a mesh made of nickel, aluminum, copper, gold, silver, an aluminum alloy, stainless steel, carbon, or the like can be used.

  As the electrode lead 106, aluminum metal, nickel metal, or the like can be used.

  As the separator 107, a porous film formed from polyethylene, polypropylene, or the like, a cellulose film, a nonwoven fabric, or the like can be used. With the separator 107, the positive electrode 101, the negative electrode 102, and the reference electrode 103 can be in a non-contact state.

  The electrolyte-containing phase may be an aqueous phase or a non-aqueous phase, but is preferably a non-aqueous phase. The electrolyte-containing phase may be solid or liquid, and in the case of a solid, for example, a gel (gel electrolyte) may be used. The electrolyte-containing phase may be formed by the electrolyte itself, or may be a solution (electrolyte) containing an electrolyte or a solid containing an electrolyte. When the electrolyte-containing phase is solid (so-called solid electrolyte, gel electrolyte, etc.), part or all of the separator 107 or the counter electrode separator 108 can be omitted. That is, in this case, instead of the separator 107 or the counter electrode separator 108, the electrolyte-containing phase itself may be interposed between the electrodes to form a separator.

  When the electrolyte-containing phase is included in the separator 107 or the counter electrode separator 108, the electrolyte-containing phase may be solid or liquid, but is preferably a solution (electrolyte) containing an electrolyte. The electrolyte solution is impregnated in each electrode of the positive electrode 101, the negative electrode 102, the reference electrode 103, and the counter electrode 104, and the electrolyte solution is in contact with each electrode, thereby transporting charge carriers between the electrodes by the electrolyte solution. It can be carried out. The charge carrier is, for example, an ion or an electron.

The ionic conductivity of the electrolytic solution is, for example, 10 ⁻⁵ to 10 ⁻¹ S / cm at 20 ° C. As the electrolytic solution, for example, an organic solvent in which an electrolyte salt is dissolved in a solvent can be used. The electrolyte salt is not particularly limited, and a known electrolyte salt or the like can be appropriately used. Examples of the electrolyte include alkali metal salts such as lithium salts. Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , Li (CF ₃ SO ₂ ) _3. C, Li (C ₂ F ₅ SO ₂ ) ₃ C and the like. Hereinafter, LiN (CF ₃ SO ₂ ) ₂ may be referred to as “LiTFSI”. In addition, LiN (C ₂ F ₅ SO ₂ ) ₂ may be referred to as “LiBETI” below.

  Examples of the organic solvent used for the non-aqueous electrolyte include carbonate, ester, ether, sulfone, and amide. Examples of the carbonate include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Examples of the ester include γ-butyrolactone. Examples of the ether include tetrahydrofuran and dioxolane. Examples of the sulfone include sulfolane. Examples of the amide include dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone and the like. These organic solvents may be used alone or in combination of two or more.

  For example, the electrolytic solution can be impregnated in a gel of a polymer compound and used as a gel electrolyte. Examples of the polymer compound include a vinylidene fluoride polymer and an acrylonitrile polymer. Examples of the vinylidene fluoride-based polymer include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-monofluoroethylene copolymer, and vinylidene fluoride. -Trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and the like. Examples of the acrylonitrile-based polymer include acrylonitrile-methyl methacrylate copolymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-ethyl methacrylate copolymer, acrylonitrile-ethyl acrylate copolymer, acrylonitrile-methacrylic acid copolymer, Examples include acrylonitrile-acrylic acid copolymer and acrylonitrile-vinyl acetate copolymer. Furthermore, examples of the polymer compound include polyethylene oxide, ethylene oxide-propylene oxide copolymers, and polymers of these acrylates and methacrylates. These polymer compounds may be used alone or in combination of two or more.

  Although it does not specifically limit as the separator 108 for counter electrodes, A cellulose, glass fiber (glass filter), a filter paper etc. can be used, A filter paper is especially preferable. When a filter paper is used as the counter electrode separator 108, the filter paper may be used singly or in an arbitrary number of two or more. The distance between the counter electrode 104 and the working electrode 103 can be adjusted by the number of the filter papers. In addition, the filter paper is likely to soak in the electrolytic solution, so that even if the thickness of the separator 108 is large, the movement of ions in the electrolytic solution is not easily inhibited.

  As the exterior body 109, a laminate film or the like formed from a metal foil such as an aluminum foil and a synthetic resin film can be used. In view of cost, usability, etc., an aluminum laminate outer package formed from an aluminum foil and a synthetic resin film is particularly preferable.

  The reference electrode current collector 111 is not particularly limited. For example, a metal foil such as platinum, nickel, copper, iron, and stainless steel, a metal wire, or the like can be used.

[Resistance measurement method and degradation degree diagnosis method]
As described above, the secondary battery of the present invention has a reference electrode and a counter electrode separately from the positive electrode and the negative electrode. As a result, the resistances of the positive electrode and the negative electrode can be measured individually and accurately, and the degree of deterioration can be easily and accurately diagnosed.

  As described above, the method for measuring the resistance of the positive electrode or the negative electrode of the secondary battery according to the present invention uses the three electrodes of the secondary battery of the present invention, the positive electrode or the negative electrode being a working electrode, and further adding a reference electrode and a counter electrode. The AC impedance at each frequency is measured (AC impedance measurement step), and the resistance of the positive electrode or the negative electrode is calculated based on the AC impedance (resistance calculation step). The AC impedance measurement step is not particularly limited except that the three electrodes are used. For example, the AC impedance measurement step can be performed in the same manner as a normal AC impedance measurement method. Although the resistance calculation step is not particularly limited, for example, a Nyquist diagram is plotted based on the AC impedance measurement result at each frequency, and the value of the diameter of the semicircle drawn in the figure is set as the charge transfer resistance. Can do.

  The method for diagnosing the degree of deterioration of the positive electrode or the negative electrode in the present invention can be performed, for example, as follows using the resistance measurement method for the positive electrode or the negative electrode of the secondary battery of the present invention. That is, first, the resistance of the positive electrode or the negative electrode after measuring at least one of charging and discharging for a predetermined time and a predetermined number of times with respect to the secondary battery of the present invention is measured by the measurement method of the present invention. (Resistance measurement process). Furthermore, the degree of deterioration of the positive electrode or the negative electrode is diagnosed by comparing the resistance of the positive electrode or the negative electrode measured in the resistance measurement step with the resistance before performing at least one of the charging and discharging (deterioration). Degree diagnosis process). The “predetermined time” and “predetermined number of times” in the charging / discharging (at least one of charging and discharging) are not particularly limited. The resistance before the charge / discharge may be measured in advance by the measurement method of the present invention, for example. For example, when the value of the resistance before the charge / discharge is known, the value may be used.

  Next, examples of the present invention will be described. However, the present invention is not limited at all by the following examples.

[Example 1]
The secondary battery of the present invention was manufactured as follows.

  First, 2.1 g of poly (2,2,6,6-tetramethylpiperidinoxyl methacrylate) (PTMA) as a positive electrode active material, 0.63 g of a carbon material as a conductivity-imparting agent, and carboxymethyl cellulose as an adhesive ( CMC) 0.24 g, polytetrafluoroethylene (PTFE) 0.03 g, and water 15 ml were stirred in a homogenizer to prepare a uniform slurry. The PTMA is a nitroxyl compound and an organic radical compound. Next, this slurry was applied on an aluminum mesh as a positive electrode current collector, further dried at 80 ° C. for 5 minutes, and further processed into a thickness of 200 μm by a roll press. The electrode thus obtained was used as a positive electrode.

  The nitroxyl polymer (poly (2,2,6,6-tetramethylpiperidinoxyl methacrylate) (PTMA)) used in this example was synthesized according to the method described in JP-A-2009-238612. did. That is, first, 20 g (0.089 mol) of 2,2,6,6-tetramethylpiperidine methacrylate monomer was placed in a 100 ml eggplant flask equipped with a reflux tube and dissolved in 80 ml of dry tetrahydrofuran. Thereto, 0.29 g (0.00187 mol) (monomer / AIBN = 50 / l) of azobisisobutyronitrile (AIBN) was added, and the mixture was reacted at 75 to 80 ° C. with stirring in an argon atmosphere. After reacting for 6 hours, it was allowed to cool to room temperature. Thereafter, the polymer was precipitated in hexane, separated by filtration, and dried under reduced pressure to obtain 18 g (yield 90%) of poly (2,2,6,6-tetramethylpiperidine methacrylate). Next, 10 g of the obtained poly (2,2,6,6-tetramethylpiperidine methacrylate) was dissolved in 100 ml of dry-treated dichloromethane. To this, 100 ml of a dichloromethane solution of 15.2 g (0.088 mol) of m-chloroperbenzoic acid was added dropwise over 1 hour with stirring at room temperature. After further stirring for 6 hours, the precipitated m-chlorobenzoic acid was removed by filtration, and the filtrate was washed with an aqueous sodium carbonate solution and water, and then dichloromethane was distilled off. The remaining solid was pulverized, and the resulting powder was washed with diethyl carbonate (DEC) and dried under reduced pressure to obtain poly (2,2,6,6-tetramethylpiperidinoxyl methacrylate) (PTMA) 7 0.2 g was obtained (yield 68.2%, brown powder). The structure of the resulting polymer compound was confirmed by IR. Moreover, as a result of measuring by GPC, the value of weight average molecular weight Mw = 89000 and dispersion degree Mw / Mn = 3.30 was obtained.

  The positive electrode obtained as described above was punched into a 22 × 20 mm rectangle, and an aluminum electrode lead having a length of 25 mm and a width of 0.4 mm was welded to the aluminum mesh surface.

  On the other hand, the negative electrode was produced as follows. That is, first, a non-graphitizable carbon slurry (manufactured by Hitachi Chemical Co., Ltd., GA1100) was applied on a copper mesh as a current collector and further dried at 80 ° C. for 5 minutes. This was processed into a thickness of 50 μm by a roll press to produce a negative electrode. The obtained negative electrode was punched into a rectangle of 23 × 21 mm in length and width, and a nickel electrode lead having a length of 25 mm and a width of 0.4 mm was welded to the copper mesh surface.

  As a reference electrode, a lithium-laminated copper foil (lithium thickness 30 μm) punched into an 8 × 5 mm rectangle, and a nickel electrode lead 25 mm long and 0.4 mm wide welded to the copper foil surface is used. It was.

  The counter electrode was produced as follows. That is, first, activated carbon slurry (manufactured by Hitachi Chemical Co., Ltd., GA1200) was applied on an aluminum mesh as a current collector and further dried at 80 ° C. for 5 minutes. This was processed into a thickness of 100 μm by a roll press machine to produce a counter electrode. The counter electrode (negative counter electrode) thus obtained was punched into a rectangle of 23 × 21 mm in length and width, and an aluminum electrode lead having a length of 25 mm and a width of 0.4 mm was welded to the aluminum mesh surface.

The positive electrode, porous polypropylene separator (27 × 25 mm rectangle), the negative electrode, porous polypropylene separator (27 × 25 mm rectangle), the reference electrode, glass fiber filter paper (27 × 25 mm rectangle), and the counter electrode are stacked in this order. In addition, a power storage unit was produced. Then, three sheets of two aluminum laminate films (length 35 mm × width 40 mm × thickness 0.12 mm) that can be heat-sealed are heat-sealed to form a bag-like aluminum laminate case, in which the power storage unit is placed. I put it in. Further, 500 mL of an electrolytic solution [ethylene carbonate / diethyl carbonate mixed solution containing 1.0 mol / L LiPF ₆ electrolyte salt (mixing volume ratio 3: 7)] was added to the aluminum laminate case. At this time, the ends of the aluminum electrode lead and the nickel electrode lead were protruded (exited) by 2.7 cm from the end of the aluminum laminate case. In that state, one side of the aluminum laminate case that was not welded was heat-sealed at a low pressure of 1.6 mmHg (2.1 × 10 ² Pa). Thus, the power storage unit including the electrodes and the electrolytic solution were completely sealed in the aluminum laminate case. In this way, the secondary battery of this example (Example 1) was manufactured.

[Example 2]
Instead of the counter electrode of Example 1, lithium-bonded copper foil (lithium thickness 30 μm) was punched into a 23 × 21 mm rectangle, and a nickel electrode lead having a length of 25 mm and a width of 0.4 mm was welded to the copper foil surface. A secondary battery of this example (Example 2) was manufactured in the same manner as Example 1 except that the obtained battery was used as the counter electrode.

[Example 3 (resistance measurement)]
Using the positive electrode in the secondary batteries of Example 1 and Example 2 as a working electrode, and using the three electrodes obtained by adding the reference electrode and the counter electrode to this, the impedance in the range of 10 mHz to 100 kHz is obtained by the AC impedance method. Measured and drawn Nyquist and Bode diagrams. The impedance of each frequency was measured using an impedance measuring device (1260 type manufactured by Solartron), and the applied voltage was in the range of −10 to 10 mV. FIG. 3 shows the Nyquist diagram and the Bode diagram. FIG. 3A is a Nyquist diagram, and FIG. 3B is a Bode diagram. In the Nyquist diagram of FIG. 3A, the x-axis represents the real part (Ω) of the impedance, and the y-axis represents the imaginary part (Ω) of the impedance. The x-axis of the Bode diagram (upper figure) in FIG. 3B represents the frequency (Hz), and the y-axis represents the absolute value (Ω) of the impedance. The x-axis of the Bode diagram (below) in FIG. 3B represents the frequency (Hz), and the y-axis represents the phase difference (°). The length of the diameter of the semicircle drawn in the Nyquist diagram of FIG. 3A indicates the magnitude of the charge transfer resistance.

As shown in FIG. 3, in both Example 1 and Example 2, the magnitude of the positive electrode resistance (charge transfer resistance) could be measured based on the positive electrode impedance measurement. From the Bode diagram (below), in Example 2, two peaks appeared at 10 ² to 10 ⁵ Hz, but in Example 1, the peak was not observed. Further, as shown in FIG. 3A, the measured resistance value in Example 1 was smaller than that in Example 2. That is, the measurement in Example 1 was possible with higher accuracy than in Example 2. This is because the resistance of the counter electrode (activated carbon) of Example 1 is smaller than that of the lithium counter electrode of Example 2 and is smaller than that of the positive electrode that is the working electrode, and therefore the influence of the resistance of the counter electrode is small. Conceivable.

[Example 4 (individual resistance measurement of positive electrode and negative electrode)]
AC impedance was measured individually in the range of 10 mHz to 100 kHz for the positive electrode and the negative electrode in the secondary battery of Example 1, and a Nyquist diagram and a Bode diagram were drawn. For the AC impedance of each frequency, an impedance measuring device (1260 type manufactured by Solartron) was used, and the applied voltage was in the range of −10 to 10 mV. Moreover, it measured using the said positive electrode or the said negative electrode as a working electrode, and also using 3 electrodes which added the reference electrode and the counter electrode. FIG. 4 shows a Nyquist diagram and a Bode diagram. FIG. 4A is a Nyquist diagram, and FIG. 4B is a Bode diagram. In the Nyquist diagram of FIG. 4A, the x-axis represents the real part (Ω) of the impedance, and the y-axis represents the imaginary part (Ω) of the impedance. The x-axis of the Bode diagram (upper figure) in FIG. 4B represents the frequency (Hz), and the y-axis represents the absolute value (Ω) of the impedance. The x-axis of the Bode diagram (below) in FIG. 4B represents the frequency (Hz), and the y-axis represents the phase difference (°).

  As shown in FIG. 4, the charge transfer resistance of the positive electrode of Example 1 was 46.0Ω, and the charge transfer resistance of the negative electrode was 53.0Ω. Thus, according to the present Example, each resistance of a positive electrode and a negative electrode was measurable individually and accurately.

  Furthermore, in the same manner, based on the alternating current impedance measurement of the positive electrode and the negative electrode of the secondary battery of the example before use (before charge / discharge) and after use (after a predetermined time and a predetermined number of times of charge / discharge). Resistance was calculated individually. By comparing the measured values (calculated values) of the resistance before and after use for the positive electrode and the negative electrode, respectively, the degree of individual deterioration of the positive electrode and the negative electrode could be easily and accurately diagnosed.

DESCRIPTION OF SYMBOLS 101 Positive electrode 102 Negative electrode 103 Reference electrode 104 Counter electrode 105 Current collector 106 Electrode lead 107 Separator 108 Counter electrode separator 109 Outer package 110 Secondary battery 111 Reference electrode current collector

Claims (10)

Including a positive electrode, a negative electrode and an electrolyte-containing phase,
The positive electrode and the negative electrode can be charged and discharged by transferring charge through the electrolyte-containing phase,
Furthermore, including a reference electrode and a counter electrode,
The reference electrode and the counter electrode are electrically connected to each other via the electrolyte-containing phase, and are electrically connected to the positive electrode and the negative electrode via the electrolyte-containing phase. Next battery.   The secondary battery according to claim 1, wherein the electrolyte-containing phase is a non-aqueous phase.   The secondary battery according to claim 1, wherein the counter electrode is made of a carbon material.   The secondary battery according to claim 3, wherein the carbon material is activated carbon.   5. The secondary battery according to claim 1, wherein a specific resistance of the counter electrode is 200 Ω · cm or less.   The secondary battery according to claim 1, wherein the reference electrode is made of lithium metal. In addition, a counter electrode separator is included,
The counter electrode separator is porous, and includes the electrolyte-containing phase in its pores.
The secondary electrode according to any one of claims 1 to 6, wherein the counter electrode is arranged in a non-contact state with the positive electrode, the negative electrode, and the reference electrode via the counter electrode separator. battery.   The secondary battery according to claim 7, wherein the counter electrode separator is filter paper. AC impedance measurement step of measuring the AC impedance of the positive electrode or the negative electrode using the positive electrode or the negative electrode as a working electrode, and further using the reference electrode and the counter electrode;
The resistance of the positive electrode or the negative electrode according to any one of claims 1 to 8, further comprising a resistance calculation step of calculating a resistance of the positive electrode or the negative electrode based on the AC impedance. Resistance measurement method. The resistance of the positive electrode or the negative electrode after the secondary battery according to any one of claims 1 to 8 is subjected to at least one of charging and discharging for a predetermined time and a predetermined number of times. A resistance measuring step of measuring by the measuring method of
Deterioration degree diagnosis step of diagnosing the degree of deterioration of the positive electrode or the negative electrode by comparing the resistance of the positive electrode or the negative electrode measured in the resistance measurement step with the resistance before performing at least one of the charging and discharging. A method for diagnosing the degree of deterioration of the positive electrode or the negative electrode of the secondary battery.

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