JP4952968B2 - Negative electrode for secondary battery and secondary battery - Google Patents

Description

The present invention relates to a negative electrode for a secondary battery containing a binder and a secondary battery using the same.

  In recent years, many portable electronic devices such as a camera-integrated VTR (video tape recorder), a mobile phone, or a laptop computer have appeared, and their size and weight have been reduced. Accordingly, as a power source for these electronic devices, research and development for improving the energy density of batteries, particularly secondary batteries, are being actively promoted. Among them, lithium ion secondary batteries using a carbon material for the negative electrode are widely put into practical use because a large energy density can be obtained as compared with conventional lead batteries and nickel cadmium batteries.

Recently, with the improvement in performance of portable electronic devices, further improvement in capacity has been demanded, and it is considered to use tin (Sn) or silicon (Si) instead of carbon material as the negative electrode active material. (For example, see Patent Document 1).
JP 2000-311681 A

  By the way, portable electronic devices are often used outdoors or used in foreign countries where the environment is different from Japan. For example, in the hot sun of countries such as the Middle East and South Africa, It is not uncommon to use it in hot and humid environments in countries like Southeast Asia. In addition, it may be left in places such as a window of strong sunlight even in the interior of a car, a cafe or an office.

  In such an environment, an insulating film is formed on the negative electrode surface mainly due to the decomposition reaction of the electrolyte, and when a binder such as polyvinylidene fluoride is used in the negative electrode, gas is released from the binder. As a result, hydrofluoric acid and trifluorobenzene are generated, an excessive insulating film is formed on the negative electrode surface, and the cycle characteristics at high temperatures are degraded.

  In addition, tin or silicon expands and contracts with charge and discharge, pulverizes, reduces current collection, or increases the surface area, which promotes the decomposition reaction of the electrolyte and produces an insulating film. There was a problem that the cycle characteristics would deteriorate.

The present invention has been made in view of such problems, and an object thereof is to provide a secondary battery capable of improving cycle characteristics even in a high temperature environment and a negative electrode for a secondary battery used therefor. is there.

The first negative electrode for a secondary battery of the present invention is a polyfluoride heated in an alkaline atmosphere containing the structural unit shown in Chemical Formula 1, the structural unit shown in Chemical Formula 2, and the structural unit shown in Chemical Formula 3. containing vinylidene as a binder, in a gas chromatogram obtained by the pyrolysis gas chromatography mass spectrometry using a temperature-temperature pyrolysis, 420 ° C. 280 ° C. or higher for the integral value a obtained by integrating the range of 680 ° C. 420 ° C. or higher The ratio (integral value B / integral value A) of the integral value B obtained by integrating the following ranges is 5% or less.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH-

The second negative electrode for a secondary battery according to the present invention is a polyfluoride heated in an alkaline atmosphere containing the structural unit shown in Chemical Formula 1, the structural unit shown in Chemical Formula 2, and the structural unit shown in Chemical Formula 3. containing vinylidene as a binder, in the mass chromatogram consisting of molecular ion 132 or fragment ions 132 obtained by thermal decomposition gas chromatograph mass spectrometry using a temperature-temperature pyrolysis, obtained by integrating the range of 580 ° C. or less 420 ° C. or higher The ratio (integral value D / integral value C) of the integral value D obtained by integrating the range of 180 ° C. to 420 ° C. with respect to the integral value C is 25% or less.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH-

A first secondary battery according to the present invention is provided with an electrolyte together with a positive electrode and a negative electrode. The negative electrode is represented by the structural unit shown in Chemical formula 1, the structural unit shown in Chemical formula 2, and the chemical formula shown in Chemical formula 3. polyvinylidene fluoride, which is heated under alkaline atmosphere containing constituent unit contained as a binder, and in a gas chromatogram obtained by the pyrolysis gas chromatography mass spectrometry using a temperature temperature pyrolysis, the range of 680 ° C. or less 420 ° C. or higher The ratio (integrated value B / integrated value A) of the integrated value B obtained by integrating the range of 280 ° C. or higher and 420 ° C. or lower with respect to the integrated value A obtained by integrating is 5% or lower.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH-

A second secondary battery according to the present invention is provided with an electrolyte together with a positive electrode and a negative electrode. The negative electrode is represented by the structural unit shown in Chemical formula 1, the structural unit shown in Chemical formula 2, and the chemical formula shown in Chemical formula 3. mass chromatogram of heated polyvinylidene fluoride in an alkaline atmosphere containing as a binder, and made of pyrolytic gas chromatography mass spectrometry molecular ion 132 or fragment ions 132 are obtained by using a temperature-temperature pyrolysis comprising a structural unit The ratio of the integrated value D obtained by integrating the range of 180 ° C. or higher and 420 ° C. or lower to the integrated value C obtained by integrating the range of 420 ° C. or higher and 580 ° C. or lower (integrated value D / integrated value C) is: 25% or less.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH-

According to the first or second negative electrode for a secondary battery of the present invention, in an alkaline atmosphere including the structural unit represented by Chemical Formula 1, the structural unit represented by Chemical Formula 2, and the structural unit represented by Chemical Formula 3 In a gas chromatogram obtained by pyrolysis gas chromatograph mass spectrometry by heating pyrolysis , containing heated polyvinylidene fluoride as a binder, the ratio of the integral value B to the integral value A is 5% or less, or In the mass chromatogram composed of molecular ions 132 or fragment ions 132 obtained by pyrolysis gas chromatograph mass spectrometry by temperature-enhanced pyrolysis, the ratio of the integrated value D to the integrated value C is set to 25% or less. Alternatively, the proportion of the structural unit shown in Chemical Formula 3 can be increased. Therefore, according to the first or the second secondary battery of the present invention using the anode for the secondary battery, it is suppressed that such gas component is removed from the binder, the excess insulating film in the negative electrode Formation can be suppressed, conductivity can be improved, and cycle characteristics can be improved even in a high temperature environment.

  Further, if the ratio of the integral value B to the integral value A is set to 3% or less, or the ratio of the integral value D to the integral value C is set to 15% or less, a higher effect can be obtained.

  In particular, it is possible to occlude and release electrode reactants in the negative electrode, and it contains a negative electrode material containing at least one of a metal element and a metalloid element as a constituent element, or it is composed of tin or silicon It is effective when the material which has as an element is contained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 illustrates a configuration of a negative electrode 10 according to an embodiment of the present invention. The negative electrode 10 includes, for example, a negative electrode current collector 11 having a pair of opposed surfaces, and a negative electrode active material layer 12 provided on one surface of the negative electrode current collector 11. Although not shown, the negative electrode active material layers 12 may be provided on both surfaces of the negative electrode current collector 11.

  The negative electrode current collector 11 preferably has good electrochemical stability, electrical conductivity, and mechanical strength, and is made of a metal material such as copper (Cu), nickel (Ni), or stainless steel. In particular, copper is preferable because it has high electrical conductivity.

  The negative electrode active material layer 12 includes, for example, any one or more negative electrode materials capable of inserting and extracting lithium or the like as a negative electrode active material. Examples of the negative electrode material capable of inserting and extracting lithium and the like include carbon materials, metal oxides, and polymer materials. Examples of carbon materials include non-graphitizable carbon, graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbons, cokes, graphites, glassy carbons, organic polymer compound fired bodies, activated carbon, and fibrous carbon. Any one or more of these carbon materials can be used. Among these, cokes include pitch coke, needle coke, and petroleum coke. Organic polymer compound fired bodies are carbonized by firing polymer compounds such as phenol resin and furan resin at an appropriate temperature. What you did. Examples of the metal oxide include tin oxide, and examples of the polymer material include polyacetylene or polypyrrole.

  As a negative electrode material capable of inserting and extracting lithium and the like, a material that can store and release lithium and the like and includes at least one of a metal element and a metalloid element as a constituent element is also included. Can be mentioned. This is because a high energy density can be obtained by using such a material. The negative electrode material may be a single element, alloy or compound of a metal element or metalloid element, or may have at least a part of one or more of these phases. In the present invention, alloys include those containing one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. Moreover, the nonmetallic element may be included. There are structures in which a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of them coexist.

  Examples of metal elements or metalloid elements constituting the negative electrode material include magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon, germanium (Ge), tin, and lead. (Pb), bismuth (Bi), cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd) or platinum (Pt). It is done. These may be crystalline or amorphous.

  Among these, as the negative electrode material, a material containing a 4B group metal element or a semimetal element in the short-period type periodic table as a constituent element is preferable, and at least one of silicon and tin is particularly preferable as a constituent element. This is because silicon and tin have a large ability to occlude and release lithium, and a high energy density can be obtained.

  Examples of tin alloys include silicon, nickel, copper, iron, cobalt (Co), manganese (Mn), zinc, indium, silver, titanium (Ti), germanium, and bismuth as the second constituent element other than tin. , Antimony (Sb), and chromium (Cr). As an alloy of silicon, for example, as a second constituent element other than silicon, among the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium The thing containing at least 1 sort (s) of these is mentioned.

  Examples of the tin compound or silicon compound include those containing oxygen (O) or carbon (C), and may contain the second constituent element described above in addition to tin or silicon.

The negative electrode active material layer 12 also contains a binder including the structural unit shown in Chemical Formula 1, the structural unit shown in Chemical Formula 2, and the structural unit shown in Chemical Formula 3.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH-

  In general, polyvinylidene fluoride containing the structural unit shown in Chemical Formula 1 as a main component reacts as shown in Chemical Formula 4 and is cyclized to produce trifluorobenzene. Since this trifluorobenzene causes deterioration of the cycle characteristics, it is preferable to suppress the deterioration of the cycle characteristics, for example, by increasing the temperature region where the cyclization reaction occurs. Specifically, in the molecular structure in which the structural unit represented by Chemical Formula 1 is polymerized, if the proportion of the structural units represented by Chemical Formula 2 and Chemical Formula 3, particularly the structural unit represented by Chemical Formula 3, is increased, the cyclization reaction will occur. It is thought that it is hard to happen.

  FIG. 2 shows an example of a mass chromatogram composed of molecular ions 132 or fragment ions 132 obtained by pyrolyzing the negative electrode 10 at elevated temperature and analyzing the generated gas components by pyrolysis gas chromatography mass spectrometry. FIG. 3 shows an example of a gas chromatogram. In this mass chromatogram, it is mainly separated into a peak P1 observed in the first region of 420 ° C. or lower and a peak P2 observed in the second region of 420 ° C. or higher, and these intersections are observed near 420 ° C. .

  As shown in FIG. 3, in the gas chromatogram, the range of 280 ° C. or more and 420 ° C. or less in the first region with respect to the integrated value A obtained by integrating the range of 420 ° C. or more and 680 ° C. or less in the second region. The ratio of the integrated value B obtained by integration (integrated value B / integrated value A) is preferably 5% or less, more preferably 3% or less. Further, as shown in FIG. 2, in the mass chromatogram composed of molecular ions 132 or fragment ions 132, the first value with respect to the integrated value C obtained by integrating the range of 420 ° C. or higher and 580 ° C. or lower in the second region. The ratio of the integrated value D (integrated value D / integrated value C) obtained by integrating the range of 180 ° C. to 420 ° C. in the region is preferably 25% or less, and more preferably 15% or less. If the ratio of the integral value is within these ranges, the proportion of the structural units shown in Chemical Formula 2 and Chemical Formula 3, especially the structural unit shown in Chemical Formula 3, is large, and the degassing reaction under high temperature environment This is because it is sufficiently suppressed and the conductivity is higher.

  The integrated value here means that in the gas chromatogram or mass chromatogram, x = each temperature, y = 0, where x is the horizontal axis (temperature axis) and y is the vertical axis (intensity axis). Means the area of the region surrounded by the outer periphery of the peak. For example, in the gas chromatogram, the integrated value obtained by integrating the range of 420 ° C. or higher and 680 ° C. or lower in the second region represents the area of the hatched region in the gas chromatogram shown in FIG. . That is, x = 420, x = 680, y = 0 and the area surrounded by the outer periphery of the peak.

  The proportion of the structural units shown in Chemical Formula 2 or Chemical Formula 3 in the binder can be increased by, for example, heating polyvinylidene fluoride in an alkaline atmosphere.

  The negative electrode 10 can be manufactured as follows, for example.

  First, for example, a negative electrode material and a binder are mixed to prepare a negative electrode mixture, and dispersed in a solvent such as N-methyl-2-pyrrolidone to prepare a negative electrode mixture slurry. Next, this negative electrode mixture slurry is applied to the negative electrode current collector 22A, dried to remove the solvent, and then compression molded by a roll press or the like to form the negative electrode active material layer 12. Thereby, the negative electrode 10 shown in FIG. 1 is obtained.

  This negative electrode 10 is used for a secondary battery as follows, for example. Note that in this embodiment, the case where lithium is used as an electrode reactant is described.

(First secondary battery)
FIG. 5 shows a cross-sectional structure of the secondary battery. This secondary battery is a so-called lithium ion secondary battery in which the capacity of the negative electrode is represented by a capacity component due to insertion and extraction of lithium. This secondary battery is a so-called cylindrical type, in which a strip-shaped positive electrode 31 and a strip-shaped negative electrode 10 are stacked and wound around a separator 32 in a substantially hollow cylindrical battery can 21. A rotating electrode body 30 is provided. The battery can 21 is made of, for example, iron plated with nickel, and has one end closed and the other end open. Inside the battery can 21, an electrolytic solution that is a liquid electrolyte is injected and impregnated in the separator 32. In addition, a pair of insulating plates 22 and 23 are respectively disposed perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 30.

  At the open end of the battery can 21, a battery lid 24, a safety valve mechanism 25 and a thermal resistance element (PTC element) 26 provided inside the battery lid 24 are interposed via a gasket 27. It is attached by caulking, and the inside of the battery can 21 is sealed. The battery lid 24 is made of the same material as the battery can 21, for example. The safety valve mechanism 25 is electrically connected to the battery lid 24 via the heat sensitive resistance element 26, and the disk plate 25A is reversed when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating. Thus, the electrical connection between the battery lid 24 and the wound electrode body 30 is cut off. When the temperature rises, the heat-sensitive resistor element 26 limits the current by increasing the resistance value, and prevents abnormal heat generation due to a large current. The gasket 27 is made of, for example, an insulating material, and asphalt is applied to the surface.

  The wound electrode body 30 is wound around a center pin 33, for example. A positive electrode lead 34 made of aluminum or the like is connected to the positive electrode 31 of the spirally wound electrode body 30, and a negative electrode lead 35 made of nickel or the like is connected to the negative electrode 10. The positive electrode lead 34 is welded to the safety valve mechanism 25 to be electrically connected to the battery lid 24, and the negative electrode lead 35 is welded to and electrically connected to the battery can 21.

  FIG. 6 shows an enlarged part of the spirally wound electrode body 30 shown in FIG. The negative electrode 10 has the above-described configuration. Thereby, the degassing reaction in a high temperature environment is suppressed, and the conductivity is improved. In FIG. 6, the negative electrode active material layer 12 is represented as being formed on both surfaces of the negative electrode current collector 11.

  The positive electrode 31 has, for example, a structure in which a positive electrode active material layer 31B is provided on both surfaces or one surface of a positive electrode current collector 31A having a pair of opposed surfaces. The positive electrode current collector 31A is made of, for example, a metal foil such as an aluminum foil. The positive electrode active material layer 31B includes, for example, any one or more of positive electrode materials capable of occluding and releasing lithium as a positive electrode active material, and artificial graphite or carbon black as necessary. And a binder such as polyvinylidene fluoride.

Examples of the positive electrode material capable of inserting and extracting lithium include metal sulfides or metal oxides that do not contain lithium, such as TiS ₂ , MoS ₂ , NbSe _{2, and} V ₂ O _5, and a chemical formula of Li _x M1O _2. (M1 represents one or more transition metals. X is different depending on the charge / discharge state of the battery, and generally 0.05 ≦ x ≦ 1.10.) Or a specific polymer etc. are mentioned. As the positive electrode material, one kind may be used alone, or two or more kinds may be mixed and used.

Among these, in the chemical formula Li _x M1O ₂ , a lithium composite oxide containing at least one member selected from the group consisting of cobalt, nickel, and manganese as the transition metal M1 is preferable. Specifically, LiCoO ₂ , LiNiO ₂ , Li _x Ni _y Co _1-y O ₂ (the value of y is 0.7 <y <1.0), LiMn ₂ O ₄ having a spinel structure, or the like. And lithium manganese composite oxide. This is because these lithium composite oxides can obtain a high voltage and a high energy density.

  In this secondary battery, the electrochemical equivalent of the negative electrode material capable of inserting and extracting lithium is larger than the electrochemical equivalent of the positive electrode 31, and lithium metal is deposited on the negative electrode 10 during charging. It is supposed not to.

  The separator 32 is made of, for example, a porous film made of synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of ceramic, and has a structure in which two or more kinds of porous films are laminated. May be.

  The separator 32 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution contains, for example, a solvent and an electrolyte salt dissolved in this solvent.

  Examples of the solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, Examples include 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, anisole, acetic acid ester, butyric acid ester or propionic acid ester. As the solvent, one kind may be used alone, or two or more kinds may be mixed and used.

For example, LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiCl, or LiBr is used as the electrolyte salt. These may be used alone or in combination of two or more.

  For example, the secondary battery can be manufactured as follows.

  First, for example, the negative electrode 10 is produced as described above. Next, for example, a positive electrode material and, if necessary, a conductive agent and a binder are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone. A mixture slurry is prepared. Next, this positive electrode mixture slurry is applied to the positive electrode current collector 31A, dried, and compression molded to form the positive electrode active material layer 31B, thereby producing the positive electrode 31.

  Subsequently, the positive electrode lead 34 is attached to the positive electrode current collector 31A by welding or the like, and the negative electrode lead 35 is attached to the negative electrode current collector 11 by welding or the like. After that, the positive electrode 31 and the negative electrode 10 are laminated and wound via the separator 32, and the tip of the positive electrode lead 34 is welded to the safety valve mechanism 25 and the tip of the negative electrode lead 35 is welded to the battery can 21. The wound positive electrode 31 and negative electrode 10 are sandwiched between a pair of insulating plates 22 and 23 and housed inside the battery can 21. Next, for example, an electrolytic solution is injected into the battery can 21 and impregnated in the separator 32. After that, the battery lid 24, the safety valve mechanism 25, and the heat sensitive resistance element 26 are fixed to the opening end of the battery can 21 by caulking through a gasket 27. Thereby, the secondary battery shown in FIGS. 5 and 6 is formed.

  In this secondary battery, when charged, lithium ions are released from the positive electrode active material layer 31 </ b> B and inserted in the negative electrode active material layer 12 through the electrolytic solution impregnated in the separator 32. Next, when discharging is performed, lithium ions are released from the negative electrode active material layer 12 and inserted in the positive electrode active material layer 31B through the electrolytic solution impregnated in the separator 32. In this secondary battery, the negative electrode 10 contains a binder containing the structural unit shown in Chemical formula 1, the structural unit shown in Chemical formula 2, and the structural unit shown in Chemical formula 3, and Since the proportion of the structural unit shown in FIG. 3, especially the structural unit shown in Chemical Formula 3, is increased, the degassing reaction in a high temperature environment is suppressed and the conductivity is improved.

  As described above, according to the secondary battery according to the present embodiment, the negative electrode 10 includes the structural unit represented by Chemical Formula 1, the structural unit represented by Chemical Formula 2, and the structural unit represented by Chemical Formula 3. In a gas chromatogram obtained by pyrolysis gas chromatograph mass spectrometry by thermal pyrolysis with temperature increase, the ratio of the integral value B to the integral value A (integral value B / integral value A) should be 5% or less, or In a mass chromatogram composed of molecular ions 132 or fragment ions 132 obtained by pyrolysis gas chromatograph mass spectrometry by temperature-enhanced pyrolysis, the ratio of the integrated value D to the integrated value C (integrated value D / integrated value C) is 25% or less. Therefore, the proportion of the constituent units shown in Chemical Formula 2 or Chemical Formula 3 can be increased. Therefore, separation of gas components and the like from the binder is suppressed, generation of an excessive insulating film in the negative electrode 10 can be suppressed, and conductivity can be improved. In addition, cycle characteristics can be improved.

  Further, if the ratio of the integral value B to the integral value A is set to 3% or less, or the ratio of the integral value D to the integral value C is set to 15% or less, a higher effect can be obtained.

  In particular, when the negative electrode 10 contains a negative electrode material capable of inserting and extracting lithium and containing at least one of a metal element and a metalloid element as a constituent element, or a constituent element of tin or silicon It is effective when it contains the material which has as.

(Secondary secondary battery)
In the second secondary battery, the capacity of the negative electrode includes a capacity component due to insertion and extraction of lithium and a capacity component due to precipitation and dissolution of lithium, and is expressed by the sum thereof.

  This secondary battery has the same configuration and effects as the first secondary battery except that the configuration of the negative electrode active material layer is different, and can be manufactured in the same manner. Therefore, here, description will be made using the same reference numerals with reference to FIGS. Detailed descriptions of the same parts are omitted.

  For example, the negative electrode active material layer 12 has an open circuit voltage (that is, a battery voltage) in the charging process by making the charge capacity of the negative electrode material capable of inserting and extracting lithium smaller than the charge capacity of the positive electrode 31. When lithium is lower than the overcharge voltage, lithium metal begins to deposit on the negative electrode 10. Therefore, in this secondary battery, both the negative electrode material capable of inserting and extracting lithium and lithium metal function as a negative electrode active material, and the negative electrode material capable of inserting and extracting lithium is lithium metal. It is a base material for precipitation. The negative electrode material capable of inserting and extracting lithium is preferably a carbon material capable of inserting and extracting lithium.

  The overcharge voltage refers to the open circuit voltage when the battery is overcharged. For example, the “lithium secondary battery” is one of the guidelines established by the Japan Storage Battery Industry Association (Battery Industry Association). Refers to a voltage that is higher than the open circuit voltage of a “fully charged” battery as defined and defined in the “Safety Evaluation Criteria Guidelines” (SBA G1101). In other words, it refers to a voltage higher than the open circuit voltage after charging using the charging method, standard charging method, or recommended charging method used when determining the nominal capacity of each battery.

  Accordingly, this secondary battery is similar to the lithium ion secondary battery in that a negative electrode material capable of inserting and extracting lithium is used for the negative electrode 10, and lithium metal is deposited on the negative electrode 10. In this respect, it is the same as the lithium metal secondary battery, but by depositing lithium metal on the negative electrode material capable of occluding and releasing lithium, high energy density can be obtained, cycle characteristics and The quick charge characteristics can be improved.

  In this secondary battery, when charged, lithium ions are released from the positive electrode 31 and are first inserted into the negative electrode material capable of inserting and extracting lithium contained in the negative electrode 10 through the electrolytic solution. When charging is further continued, lithium metal begins to deposit on the surface of the negative electrode material capable of inserting and extracting lithium in a state where the open circuit voltage is lower than the overcharge voltage. After that, lithium metal continues to deposit on the negative electrode 10 until charging is completed. Next, when discharging is performed, first, lithium metal deposited on the negative electrode 10 is eluted as ions, and is occluded in the positive electrode 31 through the electrolytic solution. When the discharge is further continued, lithium ions stored in the negative electrode material capable of inserting and extracting lithium in the negative electrode 10 are released and inserted into the positive electrode 31 through the electrolytic solution. In this secondary battery, the negative electrode 10 contains a binder containing the structural unit shown in Chemical formula 1, the structural unit shown in Chemical formula 2, and the structural unit shown in Chemical formula 3, and Chemical formula 2 and Chemical formula 3 Since the proportion of the structural units shown in (4), especially the structural units shown in Chemical Formula 3, is increased, the degassing reaction in a high temperature environment is suppressed and the conductivity is improved.

(Third secondary battery)
FIG. 7 shows the configuration of the third secondary battery. In this secondary battery, a wound electrode body 40 to which a positive electrode lead 41 and a negative electrode lead 42 are attached is accommodated in a film-like exterior member 50, and can be reduced in size, weight, and thickness. ing.

  The positive electrode lead 41 and the negative electrode lead 42 are led out from the inside of the exterior member 50 to the outside, for example, in the same direction. The positive electrode lead 41 and the negative electrode lead 42 are each made of a metal material such as aluminum, copper, nickel, or stainless steel, and each have a thin plate shape or a mesh shape.

  The exterior member 50 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. The exterior member 50 is disposed, for example, so that the polyethylene film side and the wound electrode body 40 face each other, and the outer edge portions are in close contact with each other by fusion or an adhesive. An adhesive film 51 for preventing the entry of outside air is inserted between the exterior member 50 and the positive electrode lead 41 and the negative electrode lead 42. The adhesion film 51 is made of a material having adhesion to the positive electrode lead 41 and the negative electrode lead 42, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 50 may be made of a laminated film having another structure, a polymer film such as polypropylene, or a metal film instead of the above-described aluminum laminated film.

  FIG. 8 shows a cross-sectional structure taken along line II of the spirally wound electrode body 40 shown in FIG. The wound electrode body 40 is formed by laminating the positive electrode 43 and the negative electrode 10 via the separator 44 and the electrolyte layer 45 and winding them, and the outermost peripheral portion is protected by a protective tape 46.

  The positive electrode 43 has a structure in which a positive electrode active material layer 43B is provided on one or both surfaces of the positive electrode current collector 43A. The negative electrode 10 has a structure in which a negative electrode active material layer 12 is provided on one side or both sides of a negative electrode current collector 11, and the negative electrode active material layer 12 side is disposed so as to face the positive electrode active material layer 43B. Yes. The configurations of the positive electrode current collector 43A, the positive electrode active material layer 43B, and the separator 44 are the same as those of the positive electrode current collector 31A, the positive electrode active material layer 31B, and the separator 32 described in the first or second secondary battery, respectively. is there.

  The electrolyte layer 45 includes an electrolytic solution and a polymer compound serving as a holding body that holds the electrolytic solution, and has a so-called gel shape. The gel electrolyte layer 45 is preferable because high ion conductivity can be obtained and battery leakage can be prevented. The configuration of the electrolytic solution (that is, the solvent and the electrolyte salt) is the same as that of the cylindrical secondary battery shown in FIG. The polymer compound is, for example, a fluorine polymer compound such as polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropropylene, an ether polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, or polyacrylonitrile. Etc. In particular, from the viewpoint of redox stability, a fluorine-based polymer compound is desirable.

  For example, the secondary battery can be manufactured as follows.

  First, a precursor solution containing a solvent, an electrolyte salt, a polymer compound, and a mixed solvent is applied to each of the positive electrode 43 and the negative electrode 10, and the mixed solvent is volatilized to form the electrolyte layer 45. After that, the positive electrode lead 41 is attached to the end of the positive electrode current collector 43A by welding, and the negative electrode lead 42 is attached to the end of the negative electrode current collector 11 by welding. Next, the positive electrode 43 and the negative electrode 10 on which the electrolyte layer 45 is formed are laminated through a separator 44 to form a laminated body, and then the laminated body is wound in the longitudinal direction, and the protective tape 46 is adhered to the outermost peripheral portion. Thus, the wound electrode body 40 is formed. Finally, for example, the wound electrode body 40 is sandwiched between the exterior members 50, and the outer edges of the exterior members 50 are sealed and sealed by thermal fusion or the like. At that time, the adhesive film 51 is inserted between the positive electrode lead 41 and the negative electrode lead 42 and the exterior member 50. Thereby, the secondary battery shown in FIGS. 7 and 8 is completed.

  Further, this secondary battery may be manufactured as follows. First, the positive electrode 43 and the negative electrode 10 are prepared as described above, and after the positive electrode lead 41 and the negative electrode lead 42 are attached to the positive electrode 43 and the negative electrode 10, the positive electrode 43 and the negative electrode 10 are stacked via the separator 44 and wound. Then, the protective tape 46 is adhered to the outermost peripheral portion to form a wound body that is a precursor of the wound electrode body 40. Next, the wound body is sandwiched between the exterior members 50, and the outer peripheral edge portion excluding one side is heat-sealed to form a bag shape and stored in the interior of the exterior member 50. Subsequently, an electrolyte composition including a solvent, an electrolyte salt, a monomer that is a raw material of the polymer compound, a polymerization initiator, and other materials such as a polymerization inhibitor as necessary is prepared, and the exterior Inject into the member 50.

  After injecting the electrolyte composition, the opening of the exterior member 50 is heat-sealed in a vacuum atmosphere and sealed. Next, heat is applied to polymerize the monomer to obtain a polymer compound, thereby forming the gel electrolyte layer 45, and assembling the secondary battery shown in FIGS.

  This secondary battery operates in the same manner as the first or second secondary battery, and can obtain the same effect.

  Further, specific embodiments of the present invention will be described in detail.

(Examples 1-1 to 1-4)
A negative electrode 10 was produced. First, artificial graphite as a negative electrode active material, acetylene black as a conductive agent, and a binder are mixed in a mass ratio of negative electrode active material: conductive agent: binder = 89.5: 0.5: 10, After being dispersed in N-methyl-2-pyrrolidone as a solvent to form a negative electrode mixture slurry, it is uniformly applied to the negative electrode current collector 11 made of copper foil, dried, and compression-molded with a roll press machine to produce a negative electrode active material. The material layer 12 was formed, and the negative electrode 10 was produced by punching into a pellet shape having a diameter of 15.5 mm. At that time, the binder was made by impregnating a general-purpose polyvinylidene fluoride with an alcoholic potassium hydroxide (KOH) solution and heating at 50 ° C. for 4, 3, 2, or 1 hour. A thing was used. The negative electrode active material layer 12 had a thickness of 150 μm.

The obtained negative electrode 10 was pyrolyzed at elevated temperature, and a gas chromatogram and a 132 mass chromatogram were obtained by pyrolysis gas chromatography mass spectrometry. At that time, any of GC / MS HP6890 / 5973, HP5890 / 5971, HP5890 / 5972, and HP5890 / 5973 was used as the apparatus. Moreover, Ultra alloy DTM was used for the column, and PY2020D (manufactured by Frontier Laboratories) was used for the pyrolysis furnace. Furthermore, each measurement condition was set as follows.
Temperature rising pyrolysis conditions: 80 ° C. to 700 ° C., 20 ° C./min.
GC inlet temperature: 250 ° C
Split ratio: 50: 1
GC oven temperature: 300 ° C
Carrier gas: Helium 1.5 ml / min.
Capture MS range: 45-500

  For the obtained gas chromatogram, the integral obtained by integrating the range of 280 ° C. to 420 ° C. in the first region with respect to the integral value A obtained by integrating the range of 420 ° C. to 680 ° C. in the second region. The ratio of value B [(integrated value B / integrated value A) × 100 (%)] was determined. For the 132 mass chromatogram, the integral obtained by integrating the range of 180 ° C. to 420 ° C. in the first region with respect to the integral value C obtained by integrating the range of 420 ° C. to 580 ° C. in the second region. The ratio of the value D [(integrated value D / integrated value C) × 100 (%)] was determined. These results are shown in Table 1. Moreover, the gas chromatogram and 132 mass chromatogram about the negative electrode 10 of Example 1-1 are shown to FIG. 9, 10, respectively.

  As Comparative Examples 1-1 and 1-2 for Examples 1-1 to 1-4, except that the heat treatment time in an alcoholic potassium hydroxide (KOH) solution was 0.25 hours or 0 hours, Otherwise, the negative electrode 10 was produced in the same manner as in Examples 1-1 to 1-4. The obtained negative electrodes 10 of Comparative Examples 1-1 and 1-2 were subjected to pyrolysis at elevated temperature in the same manner as in Examples 1-1 to 1-4, and gas chromatograms and 132 masses were obtained by pyrolysis gas chromatography mass spectrometry. The chromatogram was determined, and the ratio of the integral value B to the integral value A and the ratio of the integral value D to the integral value C were determined. The results are shown in Table 1.

  Next, the secondary battery shown in FIG. 11 was produced using the negative electrodes 10 of Examples 1-1 to 1-4 and Comparative Examples 1-1 and 1-2. This secondary battery is formed by laminating a positive electrode 61 and a negative electrode 10 through a separator 62 impregnated with an electrolytic solution, sandwiched between an outer can 63 and an outer cup 64, and caulked through a gasket 65. is there.

The positive electrode 61 was produced as follows. First, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed at a molar ratio of 0.5: 1, and calcined in air at 900 ° C. for 5 hours to obtain a lithium / cobalt composite oxide (LiCoO). ₂ ) got. Using this LiCoO ₂ as a positive electrode active material, LiCoO ₂ , graphite as a conductive agent, and polyvinylidene fluoride as a binder at a mass ratio of positive electrode active material: conductive agent: binder = 91: 6: 3 After mixing and dispersing in N-methyl-2-pyrrolidone as a solvent to form a positive electrode mixture slurry, this positive electrode mixture slurry is uniformly applied to a positive electrode current collector 61A made of an aluminum foil, dried, and compressed. The positive electrode active material layer 61B was formed by molding, and the positive electrode 31 was produced by punching into a pellet shape having a diameter of 15.5 mm. At that time, the thickness of the positive electrode active material layer 61B was 150 μm. The area density ratio between the negative electrode 10 and the positive electrode 61 was designed such that the capacity of the negative electrode 10 is represented by a capacity component due to insertion and extraction of lithium.

Next, after the positive electrode 61 and the negative electrode 10 were laminated via a separator 62 made of a microporous polypropylene film having a thickness of 25 μm, an electrolyte solution was injected into the separator 62. After that, they were put in an exterior cup 64 and an exterior can 63 made of stainless steel and caulked, thereby obtaining the secondary battery shown in FIG. 11 having a diameter of 20 mm and a height of 2.5 mm. As the electrolytic solution, a solution obtained by dissolving LiPF ₆ as an electrolyte salt to 1.0 mol / l in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 as a solvent was used.

  About the obtained secondary battery, the high temperature cycle characteristic was investigated as follows. First, constant current charging at 60 ° C. with a current value of 1 mA was performed until the battery voltage reached 4.2 V, then constant voltage charging was performed at a constant voltage of 4.2 V until the current value reached 0.05 mA, and then Thus, charging / discharging was performed in which constant current discharging with a current value of 1 mA was performed until the battery voltage reached 2.5V. The high-temperature cycle characteristics were determined from the discharge capacity retention rate at the 100th cycle when the discharge capacity at the first cycle was 100. The results are shown in Table 1.

  As can be seen from Table 1, according to Examples 1-1 to 1-4 in which the ratio of the integral value B to the integral value A is 5% or less, or the ratio of the integral value D to the integral value C is 25% or less. High-temperature cycle characteristics are improved as compared with Comparative Examples 1-1 and 1-2 outside these ranges, and in particular, the ratio of the integral value B to the integral value A is 3% or less, or the integral value D to the integral value C In Examples 1-1 and 1-2 in which the ratio was 15% or less, a high value was obtained for the high-temperature cycle characteristics.

  That is, if the ratio of the integral value B to the integral value A is 5% or less, or the ratio of the integral value D to the integral value C is 25% or less, the cycle characteristics are improved even in a high temperature environment. In particular, it has been found that it is preferable if the ratio of the integral value B to the integral value A is 3% or less, or the ratio of the integral value D to the integral value C is 15% or less.

(Examples 2-1 to 2-4, 3-1 to 3-4)
As Examples 2-1 to 2-4, a tin-copper alloy was used as the negative electrode active material, 54.5 parts by mass of this tin-copper alloy, and 35 parts by mass of artificial graphite that was a negative electrode active material and a conductive agent, In addition, 0.5 parts by mass of acetylene black as a conductive agent and 10 parts by mass of a binder are mixed, and N-methyl-2-pyrrolidone is added as a solvent to uniformly form a negative electrode current collector 11 made of copper foil. A negative electrode 10 and a secondary battery were produced in the same manner as in Examples 1-1 to 1-4 except that the negative electrode active material layer 12 having a thickness of 120 μm was formed by coating and drying. At that time, the same binders as in Examples 1-1 to 1-4 were used. The tin-copper alloy used was a mixture of 45 g of tin powder and 55 g of copper powder, heated to 1000 ° C. in an argon atmosphere, cooled to room temperature, and pulverized in a ball mill for 30 minutes in an argon atmosphere. It was. In addition, when the particle size was measured with a laser diffraction particle size distribution analyzer, the average particle size was 10 μm. As Comparative Examples 1-1 and 1-2 for Examples 2-1 to 2-4, except that the heat treatment time in an alcoholic potassium hydroxide (KOH) solution was 0.25 hours or 0 hours, That is, a negative electrode and a secondary battery were produced in the same manner as in Examples 2-1 to 2-4 except that the same binder as in Comparative Examples 1-1 and 1-2 was used.

  As Examples 3-1 to 3-4, silicon powder having an average particle diameter of 3 μm was used as the negative electrode active material, 90 parts by mass of this silicon powder and 10 parts by mass of the binder were mixed, and N-methyl was used as a solvent. Except that the negative electrode active material layer 12 having a thickness of 20 μm was formed by adding -2-pyrrolidone, uniformly applying to the negative electrode current collector 11 made of copper foil and drying, Example 1-1 to A negative electrode 10 and a secondary battery were produced in the same manner as in 1-4. As Comparative Examples 3-1 and 3-2 for Examples 3-1 to 3-4, except that the heat treatment time in an alcoholic potassium hydroxide (KOH) solution was 0.25 hours or 0 hours, That is, a negative electrode and a secondary battery were produced in the same manner as in Examples 3-1 to 3-4 except that the same binder as in Comparative Examples 1-1 and 1-2 was used.

  About the produced negative electrodes of Examples 2-1 to 2-4, 3-1 to 3-4 and Comparative Examples 2-1, 2-2, 3-1, 3-2, Examples 1-1 to 1-4 In the same manner as described above, thermal pyrolysis is performed, gas chromatogram and 132 mass chromatogram are obtained by pyrolysis gas chromatograph mass spectrometry, and the ratio of integral value B to integral value A and the ratio of integral value D to integral value C are obtained. It was. The results are shown in Tables 2 and 3. Moreover, also about the secondary battery, it carried out similarly to Examples 1-1 to 1-4, and investigated the high temperature cycling characteristic. The results are shown in Tables 2 and 3.

  As can be seen from Tables 2 and 3, as in Examples 1-1 to 1-4, the ratio of the integral value B to the integral value A is 5% or less, or the ratio of the integral value D to the integral value C is 25% or less. According to Examples 2-1 to 2-4 and 3-1 to 3-4, which are higher than those of Comparative Examples 2-1, 2-2, 3-1, 3-2 outside these ranges, Cycle characteristics improved. Moreover, the improvement effect was higher than Examples 1-1 to 1-4 using artificial graphite as the negative electrode active material. That is, it is possible to occlude and release the electrode reactant in the negative electrode 10, and the integral with respect to the integral value A is also included when the negative electrode material containing at least one of a metal element and a metalloid element is contained as a constituent element. If the ratio of the value B is 5% or less, or the ratio of the integral value D to the integral value C is 25% or less, the cycle characteristics can be improved even in a high temperature environment. It has been found that it is preferable if the ratio of the integral value B to A is 3% or less, or the ratio of the integral value D to the integral value C is 15% or less.

(Examples 4-1 to 4-4)
A negative electrode 10 and a secondary battery were produced in the same manner as in Examples 1-1 to 1-4 except that the thickness of the negative electrode active material layer 12 was 80 μm. The secondary battery was designed such that the capacity of the negative electrode 10 includes a capacity component due to insertion and extraction of lithium and a capacity component due to precipitation and dissolution of lithium, and is expressed by the sum thereof. As Comparative Examples 4-1 and 4-2 for Examples 4-1 to 4-4, except that the heat treatment time in the alcoholic potassium hydroxide (KOH) solution was 0.25 hours or 0 hours, That is, a negative electrode and a secondary battery were produced in the same manner as in Examples 4-1 to 4-4 except that the same binder as in Comparative Examples 1-1 and 1-2 was used.

  The produced negative electrodes of Examples 4-1 to 4-4 and Comparative Examples 4-1 and 4-2 were subjected to pyrolysis at elevated temperature in the same manner as in Examples 1-1 to 1-4, and pyrolysis gas chromatograph mass spectrometry. The gas chromatogram and 132 mass chromatogram were obtained by the method, and the ratio of the integral value B to the integral value A and the ratio of the integral value D to the integral value C were obtained. The results are shown in Table 4. Moreover, also about the secondary battery, it carried out similarly to Examples 1-1 to 1-4, and investigated the high temperature cycling characteristic. The results are shown in Table 4.

In addition, regarding the secondary batteries of Examples 4-1 to 4-4 and Comparative Examples 4-1 and 4-2, whether lithium metal and lithium ions are present in the negative electrode 10 by visual observation and ⁷ Li nuclear magnetic resonance spectroscopy I investigated whether or not.

As a result of ⁷ Li nuclear magnetic resonance spectroscopy, in the secondary batteries of Examples 4-1 to 4-4 and Comparative examples 4-1 and 4-2, a peak attributed to lithium metal in a fully charged state was confirmed, Moreover, the peak attributed to lithium ion was confirmed. On the other hand, no peak attributed to lithium metal was observed in the fully discharged state. Moreover, the lithium metal was also confirmed by visual inspection only in the fully charged state. That is, it was confirmed that the capacity of the negative electrode 10 includes a capacity component due to insertion and extraction of lithium and a capacity component due to precipitation and dissolution of lithium, and is expressed by the sum thereof.

  As can be seen from Table 4, as in Examples 1-1 to 1-4, the ratio of the integral value B to the integral value A is 5% or less, or the ratio of the integral value D to the integral value C is 25% or less. According to Examples 4-1 to 4-4, the high-temperature cycle characteristics were improved as compared with Comparative Examples 4-1 and 4-2 outside these ranges. That is, even in the case of a secondary battery in which the capacity of the negative electrode 10 includes a capacity component due to insertion and extraction of lithium and a component due to precipitation and dissolution of lithium and is represented by the sum thereof, If the ratio of the value B is 5% or less, or the ratio of the integral value D to the integral value C is 25% or less, the cycle characteristics can be improved even in a high temperature environment. It has been found that it is preferable if the ratio of the integral value B to A is 3% or less, or the ratio of the integral value D to the integral value C is 15% or less.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, a secondary battery having a winding structure or a coin-type secondary battery has been specifically described. However, the present invention is not limited to a sheet type, a button type, a square type, or the like. The present invention can be similarly applied to a secondary battery having another shape using an exterior member, or a secondary battery having a stacked structure in which a plurality of positive and negative electrodes are stacked.

  In the above embodiments and examples, the case where lithium is used as the electrode reactant has been described, but other group 1 elements in the long-period periodic table such as sodium (Na) or potassium (K), or magnesium Alternatively, the present invention can be applied to the case where a Group 2 element in a long-period periodic table such as calcium (Ca), another light metal such as aluminum, lithium, or an alloy thereof is used, and similar effects are obtained. Can be obtained. At that time, a positive electrode active material or a solvent that can occlude and release the electrode reactant is selected according to the electrode reactant.

  Furthermore, in the above-described embodiments and examples, the case where an electrolyte solution that is a liquid electrolyte is used or the case where a gel electrolyte in which the electrolyte solution is held in a polymer compound is used has been described. Other electrolytes may be used. Examples of the other electrolyte include a solid electrolyte having ion conductivity, a mixture of a solid electrolyte and an electrolytic solution, and a mixture of a solid electrolyte and a gel electrolyte.

  As the solid electrolyte, for example, a polymer solid electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, or an inorganic solid electrolyte made of ion conductive glass or ionic crystals can be used. At this time, as the polymer compound, for example, an ether polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, an ester polymer compound such as polymethacrylate, an acrylate polymer compound alone or mixed, Alternatively, it can be used by copolymerizing in the molecule. As the inorganic solid electrolyte, lithium nitride, lithium iodide, or the like can be used.

It is sectional drawing showing the structure of the negative electrode which concerns on one embodiment of this invention. It is a characteristic view showing an example of the mass chromatogram of the negative electrode of this invention. It is a characteristic view showing an example of the gas chromatogram of the negative electrode of this invention. It is a figure for demonstrating the integral value of this invention. It is sectional drawing showing the structure of the secondary battery using the negative electrode shown in FIG. FIG. 6 is an enlarged cross-sectional view illustrating a part of a wound electrode body in the secondary battery illustrated in FIG. 5. It is a disassembled perspective view showing the structure of the other secondary battery using the negative electrode shown in FIG. It is sectional drawing showing the structure along the II line of the winding electrode body shown in FIG. It is a characteristic view showing the gas chromatogram of the negative electrode produced in Example 1-1. It is the characteristic view showing the mass chromatogram of the negative electrode produced in Example 1-1. It is sectional drawing showing the structure of the secondary battery produced in the Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Negative electrode, 11 ... Negative electrode collector, 12 ... Negative electrode active material layer, 21 ... Battery can, 22, 23 ... Insulation board, 24 ... Battery cover, 25 ... Safety valve mechanism, 25A ... Disc board, 26 ... Heat resistance Element, 27, 65 ... Gasket, 30, 40 ... Winding electrode body, 31, 43, 61 ... Positive electrode, 31A, 43A, 61A ... Positive electrode current collector, 31B, 43B, 61B ... Positive electrode active material layer, 32, 44 , 62 ... separator, 33 ... center pin, 34, 41 ... positive electrode lead, 35, 42 ... negative electrode lead, 45 ... electrolyte layer, 46 ... protective tape, 50 ... exterior member, 51 ... adhesion film, 63 ... exterior can, 64 ... exterior cup.

Claims (15)

Containing 1 a constitutional unit shown in Chemical formula, a constituent unit represented by Chemical Formula 2, a polyvinylidene fluoride, which is heated under alkaline atmosphere containing a constituent unit represented by Chemical Formula 3 as a binder,
In a gas chromatogram obtained by pyrolysis gas chromatograph mass spectrometry using temperature rising pyrolysis, obtained by integrating the range of 280 ° C. to 420 ° C. with respect to the integral value A obtained by integrating the range of 420 ° C. to 680 ° C. The negative electrode for a secondary battery, wherein the ratio of the integral value B (integral value B / integral value A) is 5% or less.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH- 2. The negative electrode for a secondary battery according to claim 1 , wherein a ratio of the integrated value B to the integrated value A (integrated value B / integrated value A) is 3% or less. The negative electrode for a secondary battery according to claim 1, comprising a carbon material. 2. The negative electrode for a secondary battery according to claim 1 , wherein the negative electrode material is capable of inserting and extracting an electrode reactant and contains a negative electrode material containing at least one of a metal element and a metalloid element as a constituent element. The negative electrode for a secondary battery according to claim 1 , comprising a material containing at least one of tin (Sn) and silicon (Si) as a constituent element. Containing 1 a constitutional unit shown in Chemical formula, a constituent unit represented by Chemical Formula 2, a polyvinylidene fluoride, which is heated under alkaline atmosphere containing a constituent unit represented by Chemical Formula 3 as a binder,
In a mass chromatogram composed of molecular ions 132 or fragment ions 132 obtained by pyrolysis gas chromatograph mass spectrometry by temperature-enhanced pyrolysis, 180 ° C. or higher and 420 ° C. or higher with respect to an integral value C obtained by integrating the range of 420 ° C. or higher and 580 ° C. The negative electrode for a secondary battery, wherein the ratio of the integral value D (integral value D / integral value C) obtained by integrating the range below ° C. is 25% or less.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH- The negative electrode for a secondary battery according to claim 6 , wherein a ratio of the integrated value D to the integrated value C (integrated value D / integrated value A) is 15% or less. Bei example a cathode, an anode,
The negative electrode, a constitutional unit shown in Chemical formula 1, a constitutional unit shown in Chemical Formula 2, a polyvinylidene fluoride, which is heated under alkaline atmosphere containing a constitutional unit shown in Chemical Formula 3 contains as a binder, In a gas chromatogram obtained by pyrolysis gas chromatograph mass spectrometry by temperature-enhanced pyrolysis, obtained by integrating the range of 280 ° C to 420 ° C with respect to the integral value A obtained by integrating the range of 420 ° C to 680 ° C. The ratio of the integrated value B to be obtained (integrated value B / integrated value A) is a secondary battery having 5% or less.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH- The secondary battery according to claim 8 , wherein a ratio of the integrated value A to the integrated value B (integrated value B / integrated value A) is 3% or less. The negative electrode comprises a carbon material, a secondary battery according to claim 8. The negative electrode, it is possible to the electrode reactant occluding and releasing negative electrode material containing secondary battery according to claim 8 comprising at least one of metal elements and metalloid elements as an element. The negative electrode, tin (Sn) and contains a material containing as at least one of the constituent elements of silicon (Si), a secondary battery according to claim 8. The secondary battery according to claim 8 , wherein the capacity of the negative electrode includes a capacity component due to insertion and extraction of light metal and a capacity component due to precipitation and dissolution of light metal, and is expressed as a sum thereof. Bei example a cathode, an anode,
The negative electrode, a constitutional unit shown in Chemical formula 1, a constitutional unit shown in Chemical Formula 2, a polyvinylidene fluoride, which is heated under alkaline atmosphere containing a constitutional unit shown in Chemical Formula 3 contains as a binder, In addition, in a mass chromatogram composed of molecular ions 132 or fragment ions 132 obtained by pyrolysis gas chromatograph mass spectrometry based on thermal pyrolysis, 180 ° C. or higher with respect to an integral value C obtained by integrating a range of 420 ° C. or higher and 580 ° C. A secondary battery in which a ratio (integrated value D / integrated value C) of an integrated value D obtained by integrating a range of 420 ° C. or lower is 25% or lower.
(Chemical formula 1)
—CF ₂ —CH ₂ —
(Chemical formula 2)
-CF = CH-
(Chemical formula 3)
-CH = CH- The secondary battery according to claim 14 , wherein a ratio of the integrated value C to the integrated value D (integrated value D / integrated value C) is 15% or less.

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