JP2007299724A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery excellent in high temperature characteristics, in the case of using an aluminum material for a positive electrode collector or a positive electrode lead, capable of preventing leakage of an electrolyte composition caused by corrosion of above or degradation of a cycle maintenance rate. <P>SOLUTION: The battery is equipped with a positive electrode and a negative electrode capable of electrochemically doping/dedoping a lithium, electrolyte intervening between those positive and negative electrodes, and an external package material of a film shape storing above. At least either a positive electrode lead or a positive electrode collector is made of an aluminum material put under thermal treatment, desirably in a temperature range from 260°C to 480°C and more than 0.1 hour desirably more than 0.5 hour. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rechargeable battery including a positive electrode and a negative electrode that can be doped and dedoped with lithium, and an electrolyte, and is housed in, for example, a film-shaped exterior member or a metal can, and is particularly made of aluminum used for such a battery. The present invention relates to a positive electrode conductive member and a battery including such a positive electrode conductive member.

In recent years, many portable electronic devices such as a camera-integrated VTR (video tape recorder), a mobile phone, and a laptop computer have appeared, and their size and weight have been reduced. As a portable 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, a lithium ion secondary battery using carbon as a negative electrode active material, a lithium-transition metal composite oxide as a positive electrode active material, and a carbonate ester mixture as an electrolytic solution is a lead battery that is a conventional aqueous electrolyte secondary battery, Since a large energy density can be obtained as compared with a nickel cadmium battery, expectations are high (for example, see Patent Document 1).

As described above, the non-aqueous electrolyte is used for the lithium ion secondary battery, and a cylindrical metal container is used for the battery outer can (see, for example, Patent Document 2).
Batteries using such cylindrical metal containers have the advantage that even if electrode expansion or gas is generated in the battery due to its high strength, there is an advantage that the shape hardly changes. Electronic devices that are required to be made into a large number tend to employ many film-like ones typified by metal laminate films on the exterior (see, for example, Patent Document 3).
JP 04-332479 A JP 04-109551 A Japanese Patent Laid-Open No. 10-303084

However, in the battery as described above, when an aluminum material is used for the positive electrode conductive member, that is, the positive electrode lead or the positive electrode current collector, there are various problems due to corrosion of the aluminum material by an electrolyte composition such as an electrolytic solution. It is done.
For example, in a battery using a film-like exterior member, it cannot be said that there is no possibility of electrolyte leakage from an aluminum positive electrode lead, and when an aluminum positive electrode current collector is corroded (oxidized) by an electrolyte. In addition, aluminum may elute and deposit instead of lithium, which may reduce the cycle retention rate, and prevent such leakage due to corrosion of the positive electrode conductive member and the decrease in cycle retention rate. Has been a problem in conventional batteries.

  The present invention has been made in view of such problems of the prior art, and the object thereof is excellent in corrosion resistance, leakage of the electrolyte composition due to corrosion, and reduction in cycle maintenance rate. An object of the present invention is to provide an aluminum positive electrode conductive member that can be prevented and a battery using such a conductive member.

  As a result of repeating earnest studies to achieve the above object, the present inventors solved the above object by subjecting the aluminum material for the positive electrode conductive member such as the positive electrode lead and the positive electrode current collector to a heat treatment at a predetermined temperature. The present inventors have found that the present invention can be accomplished and have completed the present invention.

That is, the positive electrode conductive member of the present invention is characterized by being made of an aluminum material that has been heat-treated at a temperature of 240 ° C. or higher.
Further, the positive electrode conductive member of the present invention is made of an aluminum material, and when a current value at a potential of 5 V in a cyclic voltammogram using an aluminum O material as a working electrode is 1, a potential of 5 V using the aluminum material as a working electrode. When the current value at a potential of 5 V in a cyclic voltammogram using an aluminum H material as a working electrode is 1, the current value at the potential of 5 V using the aluminum material as a working electrode is The current value is 0.5 or less, or the average crystal grain size of the aluminum material is 11.5 μm or more, or within 30 ° from each crystal direction of <001>, <101> and <111> in the aluminum material. In the cross-sectional crystal distribution, the ratio within 30 ° from <111> is 0.7% or more, or the total grain boundary of the aluminum material It is characterized in that the ratio of Σ1 value for is not more than 62.7%.

  The battery of the present invention is a battery including a positive electrode and a negative electrode that can be electrochemically doped and dedoped with lithium, an electrolyte composition interposed between the positive electrode and the negative electrode, and an exterior member that accommodates them. The positive electrode lead and / or the positive electrode current collector is made of an aluminum material that has been heat-treated at a temperature of 240 ° C. or higher.

  According to the present invention, the positive electrode conductive member is made of an aluminum material that has been heat-treated at a temperature of 240 ° C. or higher, or the current value at a potential of 5 V in the cyclic voltammogram is 90% of the current value of the aluminum O material. Because it is made of the following aluminum material, or it is made of an aluminum material whose current value at a potential of 5 V in the cyclic voltammogram is 50% or less of the current value of the aluminum H material, or the average crystal grain size is 11.5 μm. Aluminum which is made of the above aluminum material or has a ratio of within 30 ° from <111> to 0.7% or more in the cross-sectional crystal distribution within 30 ° from each crystal direction of <001> <101> <111> Because it is made of material, or divided by the Σ1 value against the total number of grain boundaries Is made of an aluminum material of 62.7% or less, and therefore has excellent corrosion resistance. By using such a positive electrode conductive member as a positive electrode lead or a positive electrode current collector of a battery, an electrolyte composition based on these corrosions can be used. Leakage and reduction in cycle maintenance rate can be prevented.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. In the present specification and claims, “%” represents mass percentage unless otherwise specified.

FIG. 1 shows a cross-sectional structure of a cylindrical lithium ion secondary battery as an example of an embodiment of the present invention. The secondary battery has a negative electrode capacity of lithium (Li), which is an electrode reactant. It is represented by a capacity component due to occlusion and release.
The secondary battery includes a wound electrode body 20 in which a pair of belt-like positive electrodes 21 and a belt-like negative electrode 22 are stacked and wound via a separator 23 inside a substantially hollow cylindrical battery can 11. Have.

The battery can 11 is made of a steel material (Fe) plated with nickel (Ni), for example, and has one end closed and the other end open.
An electrolytic solution is injected into the battery can 11, and the separator 23 is impregnated with the electrolytic solution. In addition, a pair of insulating plates 12 and 13 are arranged perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 20.

  At the open end of the battery can 11, a battery lid 14, a safety valve mechanism 15 provided inside the battery lid 14, and a thermal resistance element (PTC element) 16 are interposed via a gasket 17. The battery can 11 is attached by being caulked, and the inside of the battery can 11 is sealed. The battery lid 14 is made of, for example, the same material as that of the battery can 11, and the gasket 17 is made of, for example, an insulating material, and the surface is coated with asphalt.

The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16, and when the internal pressure of the battery exceeds a predetermined value due to internal short circuit or external heating, the disk plate 15A is reversed and the electrical connection between the battery lid 14 and the wound electrode body 20 is cut off.
The heat sensitive resistance element 16 limits the current by increasing the resistance value when the temperature rises, and prevents abnormal heat generation due to a large current.

  For example, a center pin 24 is inserted in the center of the wound electrode body 20. On the other hand, a positive electrode lead 25 made of aluminum (Al) or the like is connected to the positive electrode 21 of the spirally wound electrode body 20, and a negative electrode lead 26 made of nickel or the like is connected to the negative electrode 22. The positive electrode lead 25 is electrically connected to the battery lid 14 by being welded to the safety valve mechanism 15, and the negative electrode lead 26 is welded to and electrically connected to the battery can 11.

FIG. 2 shows an enlarged part of the spirally wound electrode body 20 shown in FIG. 1, and the positive electrode 21 has a structure in which, for example, a positive electrode active material layer 21B is provided on both surfaces of a positive electrode current collector 21A. have.
Generally, a metal foil made of aluminum, copper, nickel, stainless steel, or the like is applied to the positive electrode current collector 21A. In the present invention, at least one of the positive electrode current collector 21A and the positive electrode lead 25 described above is used. In addition, an aluminum material that has been heat-treated at a temperature of 240 ° C. or higher is used, thereby preventing dissolution due to corrosion of the aluminum material and decomposition of the electrolyte, thereby improving cycle characteristics as a secondary battery. it can.

The positive electrode current collector 21A and the positive electrode lead 25 have different contact areas and contact forms with the electrolytic solution, and the corrosion ability of the electrolytic solution with respect to aluminum differs depending on the type. Although it is not necessary to heat-treat both of the leads 25, in the case of such a cylindrical lithium ion secondary battery, it is necessary to heat-treat the positive electrode current collector 21A having a large area with the electrolytic solution. In particular, when a highly oxidizing electrolytic solution using a cyclic imide salt, which will be described later, is used as the electrolyte salt, it is desirable to use a heat-treated aluminum material for the positive electrode lead 25 as well.
Note that an aluminum material that has been subjected to a predetermined heat treatment may be used for either the positive electrode current collector 21A or the positive electrode lead 25, and copper, nickel, stainless steel, or the like other than aluminum may be used for the other. .

As the heat treatment conditions for the aluminum material, when the heat treatment temperature is lower than 240 ° C., the annealing is insufficient and the above effect cannot be obtained sufficiently. The upper limit of the treatment temperature is not particularly limited, but it is preferable that the treatment is performed at a temperature of up to about 480 ° C. from the viewpoint of avoiding unnecessary energy consumption in the treatment at an excessively high temperature as well as the tendency to deteriorate. .
Further, the treatment time is preferably 0.1 hour (6 minutes) or longer. As the heat treatment conditions, it is more preferable that the heat treatment temperature is 260 ° C. and the time is 0.5 hours (30 minutes) or more from the viewpoint of ensuring the effect.

The positive electrode active material layer 21B includes, for example, one or two or more positive electrode materials that can be electrochemically doped and dedoped with lithium (Li) as a positive electrode active material. A conductive material such as a carbon material and a binder such as polyvinylidene fluoride may be included. As such a positive electrode material, for example, a chalcogenide containing no lithium such as titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), niobium selenide (NbSe ₂ ), or vanadium oxide (V ₂ O ₅ ), or The lithium containing compound containing lithium is mentioned.

Among these, lithium-containing compounds are preferable because some compounds can obtain a high voltage and a high energy density. Examples of such a lithium-containing compound include a composite oxide containing lithium and a transition metal element, or a phosphoric acid compound containing lithium and a transition metal element. Those containing at least one of cobalt (Co), nickel (Ni) and manganese (Mn) are preferred.
The chemical formula can be represented by, for example, Li _x MIO ₂ or Li _y MIIPO ₄ , where MI and MII represent one or more transition metal elements. On the other hand, the values of x and y vary depending on the charge / discharge state of the battery, and are usually in the range of 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Specific examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), and lithium nickel cobalt composite oxide (Li _x Ni _1-z Co _z O 2 (z <1)), lithium nickel cobalt manganese composite oxide (Li _x Ni _(1-vw) Co _v Mn _w O ₂ (v + w <1)), or spinel structure And lithium manganese composite oxide (LiMn ₂ O ₄ ).
In particular, a composite oxide containing nickel is preferable. This is because a high capacity can be obtained and excellent cycle characteristics can be obtained.

Specific examples of the phosphate compound containing lithium and a transition metal element include, for example, a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (u <1)). Is mentioned.

  The negative electrode 22 has, for example, a structure in which a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A, as with the positive electrode 21. The negative electrode current collector 22A is made of a metal foil such as copper (Cu), for example.

  This negative electrode material includes non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, glassy carbons, organic polymer compound firing Carbonaceous materials such as carbon (phenol resin, furan resin, etc., calcined and carbonized), carbon fiber, activated carbon, carbon black and the like can be used.

Examples of the metal element or metalloid element constituting the negative electrode material include a metal element or metalloid element capable of forming an alloy with lithium.
Specifically, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), Examples thereof include bismuth (Bi), cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd), and platinum (Pt). Among these, silicon or tin is particularly preferable because it has a large ability to occlude and release lithium and can obtain a high energy density.

As such a negative electrode material, for example, tin is a first constituent element, and a material containing a second constituent element and a third constituent element in addition to tin is preferable.
As the second constituent element, cobalt, iron (Fe), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese, nickel, copper, zinc (Zn), gallium (Ga) , Zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), indium (In), cerium (Ce), hafnium (Hf), tantalum (Ta), tungsten (W), bismuth (Bi) And at least one member of the group consisting of silicon.
The third constituent element is at least one selected from the group consisting of boron, carbon (C), aluminum, and phosphorus (P).
By including these second and third elements, the cycle characteristics can be improved.

  Among these, as such a negative electrode material, tin, cobalt, and carbon are included as constituent elements, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and tin and cobalt The ratio of cobalt to the total content of Co / (Sn + Co) is preferably an Sn—Co—C-containing material having a mass ratio of 30% to 70% by mass. That is, it is because a high energy density can be obtained in such a composition range, and excellent cycle characteristics can be obtained.

  This Sn—Co—C-containing material may further contain other constituent elements as necessary. As such other constituent elements, for example, silicon, iron, nickel, chromium, indium, niobium, germanium (Ge), titanium, molybdenum, aluminum, phosphorus, gallium, or bismuth are preferable. May be included. As a result, the capacity or cycle characteristics can be further improved.

Note that this Sn—Co—C-containing material has a phase containing tin, cobalt, and carbon, and this phase preferably has an amorphous or low crystallinity structure. In this Sn—Co—C-containing material, it is preferable that at least a part of carbon as a constituent element is bonded to a metal element or a metalloid element as another constituent element.
In other words, the decrease in cycle characteristics is thought to be due to the aggregation or crystallization of tin or the like, but the fact that such aggregation or crystallization can be suppressed by combining carbon with other elements. .

  As an analysis method for examining the bonding state of elements, for example, X-ray photoelectron spectroscopy (XPS) can be given.

In this XPS measurement, if the peak of carbon 1s orbital (C1s) is graphite, it is 284.5 eV in an apparatus calibrated so that the peak of gold atom 4f orbital (Au4f) is obtained at 84.0 eV. Appears in Moreover, if it is surface contamination carbon, it will appear at 284.8 eV. On the other hand, when the charge density of the carbon element is high, for example, when carbon is bonded to a metal element or a metalloid element, the C1s peak appears in a region lower than 284.5 eV.
That is, when the peak of the synthetic wave of C1s obtained for the Sn—Co—C containing material appears in a region lower than 284.5 eV, at least part of the carbon contained in the Sn—B—Co—C containing material is present. It is combined with other constituent elements, metal elements or metalloid elements.

  In XPS measurement, for example, the C1s peak is used to correct the energy axis of the spectrum. Usually, since surface-contaminated carbon exists on the surface, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, which is used as an energy standard. In the XPS measurement, the waveform of the C1s peak is obtained as a form including the surface contamination carbon peak and the carbon peak in the Sn-Co-C-containing material. Therefore, for example, analysis using commercially available software is required. Thus, the surface contamination carbon peak and the carbon peak in the Sn—Co—C-containing material are separated. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

  In this embodiment, by adjusting the amount of the positive electrode active material and the negative electrode material capable of doping and dedoping lithium, the negative electrode capable of doping and dedoping lithium rather than the charge capacity of the positive electrode active material. The charge capacity of the material can be increased, and lithium metal can be prevented from depositing on the negative electrode 22 even during complete charging.

  The separator 23 has a function of allowing the lithium ions to pass while isolating the positive electrode 21 and the negative electrode 22 and preventing a short circuit of current due to contact between the two electrodes. The separator 23 is made of, for example, a porous film made of a synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of a ceramic, and has a structure in which two or more kinds of porous films are laminated. It can also be.

The electrolytic solution impregnated in the separator 23 includes a solvent and an electrolyte salt dissolved in the solvent. Examples of the solvent include non-aqueous solvents such as carbonate esters.
Non-aqueous solvents are classified into, for example, a high-boiling solvent having a boiling point higher than 150 ° C. and a low-boiling solvent having a boiling point of 150 ° C. or lower at atmospheric pressure (1.01325 × 10 ⁵ Pa). It is preferable to use these because high ion conductivity can be obtained.

  Examples of the high boiling point solvent include ethylene carbonate, propylene carbonate, butylene carbonate, cyclic carbonates such as 1,3-dioxol-2-one, lactones such as γ-butyrolactone and γ-valerolactone, 2-methyl- Examples include lactams such as 1-pyrrolidone, cyclic carbamates such as 3-methyl-2-oxazolidinone, and cyclic sulfones such as tetramethylene sulfone.

Examples of the low boiling point solvent include chain carbonate esters such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl isobutyrate, or trimethylacetic acid. Chain carboxylic acid esters such as methyl, ketones such as pinacholine, 1,2-dimethoxyethane, tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 1,3-dioxane, ethers such as 1,4-dioxane, N, Examples thereof include chain amides such as N-dimethylformamide and N, N-dimethylacetamide, or chain carbamic acid esters such as methyl N, N-dimethylcarbamate and methyl N, N-diethylcarbamate.
Any one of these solvents may be used alone, or two or more thereof may be mixed and used.

  As the high boiling point solvent, 4-fluoro-1,3-dioxolan-2-one should be used because the decomposition reaction of the electrolytic solution in the negative electrode 22 can be suppressed and the cycle characteristics can be improved. Is more preferable. Vinylene carbonate and vinyl ethylene carbonate have the same effect. Further, propane sultone and propene sultone which are sultone compounds can be expected to have the same effect.

The electrolyte salt dissolved in the non-aqueous solvent preferably contains a cyclic imide salt represented by the chemical formula (1), whereby the surface of the positive electrode 21 or the negative electrode 22 is stable even at high temperatures. Thus, the decomposition reaction of the electrolytic solution at a high temperature can be suppressed, and the cycle retention rate can be improved.
The electrolyte containing such a cyclic imide salt is particularly strong in oxidization, and aluminum is easily eluted from the positive electrode current collector 21A and the positive electrode lead 25, thereby improving the cycle retention rate by the cyclic imide salt. Although there is a possibility that it will not be fully exhibited, the elution of aluminum is suppressed by heat-treating these aluminum agents, and the effect of the cyclic imide salt can be sufficiently obtained. When it is applied to a battery using an electrolytic solution containing, particularly remarkable effects are exhibited.

The cyclic imide salt is represented by the general formula of chemical formula (1), and specifically, in addition to 1,3-perfluoropropanedisulfonylimide lithium represented by the following chemical formula (2), 1,2-perfluoroethane disulfonylimide lithium, 1,3-perfluorobutane disulfonylimide lithium, 1,4-perfluorobutane disulfonylimide lithium, perfluoroheptane disulfonylimide lithium, etc. can be used. .
This imide salt may be used alone or in combination of two or more. In addition, as content in the electrolyte solution of the said cyclic imide salt, it is preferable to set it as the range of 0.01-2 mol / L or less. This is because if the cyclic imide salt content is less than 0.01 mol / L, the effect of suppressing the decomposition of the electrolyte solution is low, and if it exceeds 2 mol / L, the viscosity of the electrolyte solution increases and the ionic conductivity decreases. Due to the tendency.

In addition, the electrolyte salt in the non-aqueous electrolyte solution may be constituted only by the cyclic imide salt, but may be used by mixing with one or more other lithium salts.
Other lithium salts include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium bis (trifluoromethanesulfone) imide (LiN (CF ₃ SO ₂ ) ₂ ), lithium bis (Pentafluoroethanesulfone) imide (LiN (C ₂ F ₅ SO ₂ ) ₂ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium perchlorate (LiClO ₄ ), lithium methanesulfonate (CH ₃ SO ₃ Li ), Lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium chloride (LiCl), lithium bromide (LiBr), lithium tetraphenylborate (LiB (C ₆ H ₅ ) ₄ ), lithium tris (trifluoromethanesulfonyl) methide _{(LiC (CF 3 SO 2)} 3), lithium Bisuo Saleh oxalatoborate _{(LiB (C 2 O 4)} 2) , and the like. Among them, it is preferable to mix and use lithium hexafluorophosphate and lithium bisoxalate borate since higher characteristics can be obtained.

  In the present invention, the electrolyte composition includes not only the above-described non-aqueous electrolyte solution but also a solid electrolyte containing an electrolyte salt and a gel electrolyte in which an organic polymer is impregnated with a non-aqueous solvent and an electrolyte salt. In addition, in the cylindrical lithium ion secondary battery described so far, the non-aqueous electrolyte as described above is used as the electrolyte composition.

  Such a secondary battery can be manufactured as follows, for example.

First, for example, the positive electrode active material layer 21B is formed on the positive electrode current collector 21A to produce the positive electrode 21. The positive electrode active material layer 21B is prepared, for example, by mixing a positive electrode active material powder, a conductive material, and a binder to prepare a positive electrode mixture, and then using the positive electrode mixture in a solvent such as N-methyl-2-pyrrolidone. The positive electrode mixture slurry is dispersed to form a positive electrode mixture slurry, and the positive electrode mixture slurry is applied to the positive electrode current collector 21A, dried, and compression molded.
Then, in the same manner as the positive electrode 21, the negative electrode active material layer 22 </ b> B is formed on the negative electrode current collector 22 </ b> A to produce the negative electrode 22.

Next, the positive electrode lead 25 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A by welding or the like.
Subsequently, the positive electrode 21 and the negative electrode 22 are wound through the separator 23, and the tip of the positive electrode lead 25 is welded to the safety valve mechanism 15, and the tip of the negative electrode lead 26 is welded to the battery can 11. The positive electrode 21 and the negative electrode 22 are sandwiched between a pair of insulating plates 12 and 13 and stored in the battery can 11.

  After the positive electrode 21 and the negative electrode 22 are accommodated in the battery can 11, the electrolytic solution is injected into the battery can 11 and impregnated in the separator 23. After that, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are fixed to the opening end of the battery can 11 by a gasket 17, thereby the secondary battery shown in FIGS. Is completed.

In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution. When discharging is performed, for example, lithium ions are released from the negative electrode 22 and inserted in the positive electrode 21 through the electrolytic solution.
At that time, the positive electrode current collector 21A and the positive electrode lead 25 are made of an aluminum material that has been subjected to a predetermined heat treatment, so that the cyclic imide salt represented by the chemical formula (1) is contained as usual. Even when a highly oxidizable electrolyte is used, aluminum is not corroded and eluted into the electrolyte, and the chemical stability of the electrolyte at high temperatures can be improved. The high temperature characteristics of can be improved.

  FIG. 3 shows a configuration of a laminated film type secondary battery as another example of the embodiment of the present invention. The secondary battery includes a wound electrode to which a positive electrode lead 31 and a negative electrode lead 32 are attached. The body 30 is accommodated in a film-shaped exterior member 40.

The positive electrode lead 31 and the negative electrode lead 32 are respectively led out from the inside of the exterior member 40 to the outside, for example, in the same direction.
The positive electrode lead 31 and the negative electrode lead 32 are generally formed into a thin plate shape from a metal material such as aluminum, copper, nickel, or stainless steel. In the present invention, the positive electrode lead 31 is predetermined as described later. The aluminum material that has been subjected to the heat treatment is used.

The exterior member 40 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. For example, the exterior member 40 is disposed so that the polyethylene film side and the wound electrode body 30 face each other, and the outer edge portions are in close contact with each other by fusion bonding or an adhesive.
An adhesion film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32 to prevent intrusion of outside air. The adhesion film 41 is made of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 40 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.

Here, the general structure of an exterior member can be represented by the laminated structure of an exterior layer / metal foil / sealant layer (however, the exterior layer and the sealant layer may be composed of a plurality of layers), and the above. In this example, the nylon film corresponds to the exterior layer, the aluminum foil corresponds to the metal foil, and the polyethylene film corresponds to the sealant layer.
In addition, as metal foil, it is sufficient if it functions as a moisture-permeable barrier film, and not only aluminum foil but also stainless steel foil, nickel foil and plated iron foil can be used, but it is thin and lightweight. Thus, an aluminum foil excellent in workability can be suitably used.

  The structures that can be used as the exterior member are listed in the form of (exterior layer / metal foil / sealant layer): Ny (nylon) / Al (aluminum) / CPP (unstretched polypropylene), PET (polyethylene terephthalate) / Al / CPP, PET / Al / PET / CPP, PET / Ny / Al / CPP, PET / Ny / Al / Ny / CPP, PET / Ny / Al / Ny / PE (polyethylene), Ny / PE / Al / LLDPE (direct) Chain low density polyethylene), PET / PE / Al / PET / LDPE (low density polyethylene), and PET / Ny / Al / LDPE / CPP.

FIG. 4 shows a cross-sectional structure taken along line II of the spirally wound electrode body 30 shown in FIG. In the figure, an electrode winding body 30 is formed by laminating a pair of a positive electrode 33 and a negative electrode 34 via a separator 35 and an electrolyte layer 36, and the outermost peripheral portion is protected by a protective tape 37. .
FIG. 4 illustrates the case where the positive electrode 33 and the negative electrode 34 are wound in a state in which the separator 35 and the electrolyte layer 36 are interposed, but the present invention is not limited to such a winding method. Needless to say, the present invention can also be applied to a lamination method in which an electrode, a separator, and an electrolyte are sequentially laminated.

Here, the positive electrode 33 has a structure in which the positive electrode active material layer 33B is provided on both surfaces of the positive electrode current collector 33A. The negative electrode 34 has a structure in which a negative electrode active material layer 34B is provided on both surfaces of a negative electrode current collector 34A, and the negative electrode active material layer 34B and the positive electrode active material layer 33B are arranged to face each other.
The configuration of the positive electrode current collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, the negative electrode active material layer 34B, and the separator 35 is the same as that of the positive electrode current collector 21A, the positive electrode active material layer 21B in the cylindrical battery described above. This is substantially the same as the negative electrode current collector 22A, the negative electrode active material layer 22B, and the separator 23.

In the present invention, an aluminum material heat-treated at a temperature of 240 ° C. or higher is used for at least one of the positive electrode current collector 33A and the positive electrode lead 31 described above, thereby causing corrosion of the aluminum material. Cycle characteristics as a secondary battery can be improved by suppressing dissolution and decomposition of the electrolytic solution.
In such a laminate type battery, a boundary line is formed between a portion that contacts the electrolyte solution and a portion that does not contact the positive electrode lead 31, and aluminum is dissolved by forming a local battery at the boundary portion during charging. Since it is estimated that the electrolyte solution leaks from the melting portion, the leakage of the electrolyte solution from the positive electrode lead 31 portion can be prevented by applying the above-mentioned heat-treated aluminum material to the positive electrode lead 31 in particular. However, when a highly oxidizable electrolyte containing a cyclic imide salt is used, it is desirable to apply a heat-treated aluminum material to the positive electrode current collector 33A.

For the electrolyte layer 36, the same electrolytic solution as that of the cylindrical battery described above can be applied.
In such a laminate film type secondary battery, a so-called gel electrolyte containing the above electrolyte and a polymer compound that serves as a holding body for holding the electrolyte can also be used. The electrolyte is preferable because it can obtain high ionic conductivity and prevent battery leakage.

  Examples of the polymer compound include, for example, an ether polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, an ester polymer compound such as polymethacrylate, or an acrylate polymer compound, or polyvinylidene fluoride or vinylidene fluoride. A polymer of vinylidene fluoride such as a copolymer with hexafluoropropylene can be used, and any one or a mixture of two or more of these can be used. In particular, from the viewpoint of redox stability, it is desirable to use a fluorine-based polymer compound such as a vinylidene fluoride polymer.

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

First, a precursor solution containing an electrolytic solution, a polymer compound, and a mixed solvent is applied to each of the positive electrode 33 and the negative electrode 34, and the mixed solvent is volatilized to form the electrolyte layer 36. Next, the positive electrode lead 31 is attached to the positive electrode current collector 33A, and the negative electrode lead 32 is attached to the negative electrode current collector 34A.
Subsequently, the positive electrode 33 and the negative electrode 34 on which the electrolyte layer 36 is formed are laminated via a separator 35 to form a laminated body, and then the laminated body is wound in the longitudinal direction, and the protective tape 37 is attached to the outermost peripheral portion. The wound electrode body 30 is formed by bonding. After that, for example, the wound electrode body 30 is sandwiched between the exterior members 40, and the outer edge portions of the exterior members 40 are sealed and sealed by thermal fusion or the like. At that time, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40. Thereby, the secondary battery shown in FIGS. 3 and 4 is completed.

The secondary battery may be manufactured as follows.
That is, first, the positive electrode 33 and the negative electrode 34 are prepared as described above, the positive electrode lead 31 and the negative electrode lead 32 are attached to the positive electrode 33 and the negative electrode 34, respectively, and then the positive electrode 33 and the negative electrode 34 are stacked via the separator 35. Then, the protective tape 37 is adhered to the outermost peripheral portion to form a wound body that is a precursor of the wound electrode body 30.

  Next, the wound body is sandwiched between the exterior members 40, and the outer peripheral edge portion excluding one side is heat-sealed to form a bag shape, and is stored inside the exterior member 40. Subsequently, an electrolyte composition including an electrolytic solution, 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 interior of the exterior member 40 Then, the opening of the exterior member 40 is heat-sealed and sealed. Thereafter, heat is applied to polymerize the monomer to obtain a polymer compound, thereby forming the gel electrolyte layer 36, and assembling the secondary battery shown in FIGS.

  The secondary battery described above operates in the same manner as the cylindrical secondary battery described above, and the same effect can be obtained.

  In the battery of the present invention, as described above, the aluminum material used for the positive electrode current collector and the positive electrode lead is heat-treated (annealed) at a temperature of 240 ° C. or higher, and thereby, the cycle characteristics of the secondary battery. It is possible to prevent the leakage from the positive electrode lead due to corrosion.

Therefore, in order to investigate the reason why these characteristics and the reliability of the battery are improved by heat-treating the aluminum material, the reactivity between the electrolytic solution and the aluminum material was investigated.
That is, cyclic voltammetry was measured at a scanning speed of 10 mV / sec under a measurement environment of 25 ° C. using a three-electrode cell using an electrochemical measurement system HZ-3000 manufactured by Hokuto Denko Corporation.

The tripolar cell uses a lithium foil as a reference electrode (RE) and a counter electrode (CE), and as a working electrode (WE), an aluminum foil O material made of Japanese foil (corresponding to A8021-O defined in JIS H4160) and The H material (equivalent to A8021-H18) and the heat treatment material of the O material (350 ° C. × 7 hours heating and slow cooling) were used.
The electrolyte is propylene carbonate (PC), the electrolyte is lithium hexafluorophosphate (LiPF ₆ ), lithium bis (trifluoromethanesulfone) imide (LiN (CF ₃ SO ₂ ) ₂ ), and chemical formula (2). In addition, a solution in which 0.6 mol / L of 1,3-perfluoropropanedisulfonylimide lithium was dissolved, and three types of convenient electrolytes were used. The results are shown in FIGS.

FIG. 5 shows the result of evaluating each aluminum foil with an electrolytic solution using LiPF ₆ as an electrolyte. As can be seen from FIG. 5, the H material has a large current value at 5 V, and then the O material, It becomes small in order of the heat treatment material of O material.
Since the current value indicates dissolution of aluminum or decomposition of the electrolytic solution, the smaller the current value, the better the conductive member of the battery. This is considered to be the reason why the battery characteristics were improved by heat-treating the aluminum foil.

  Moreover, FIG. 6 shows the result evaluated using the electrolyte solution using the 1, 3- perfluoropropane disulfonyl imide lithium shown in Chemical formula (2) as an electrolyte, Comprising: It is the same as that of FIG. It shows a trend.

FIG. 7 shows the same cyclic voltammetry in which the surface of each aluminum foil of the O material and its heat-treated material was polished with a sandpaper (grain size # 220) and the aluminum surface film was removed as a working electrode. It is understood that even when the surface of the aluminum foil is treated with sandpaper and the surface film is removed, the current value of the heat-treated material is small.
5, 6, and 7, the current value at the potential of 5 V of the heat treatment material of the O material is 90% of the current value at the potential of 5 V of the non-heat treatment O material and the H material, respectively. Hereinafter, it is understood that it is 50% or less.

  FIG. 8, FIG. 9 and FIG. 10 show three kinds of aluminum materials, FIB heat treatment material (350 ° C. × slow cooling after 7 hours), O material non-heat treatment material and H material non-heat treatment material. (FocusedIon Beam) Each cross-section is formed by processing, and the structure is observed with a scanning ion microscope (SIM) of the same apparatus, and the heat treatment is performed. It is confirmed that the crystal particles are enlarged due to the crystallization, and the reactivity with the electrolytic solution is suppressed by increasing the crystal particles, and the corrosion of the aluminum material is suppressed. As the FIB apparatus, an FB-2000A type manufactured by Hitachi, Ltd. was used.

For such a corrosion inhibiting effect, it is desirable that the average crystal grain size is 11.5 μm or more, further 12.0 μm or more.
In addition, in order to obtain | require the average particle diameter of a crystal grain, it can obtain | require, for example by the EBSP (Electron Backscatter Diffraction Pattern: Electron back diffusion diffraction image) method. In this EBSP method, by analyzing a channeling pattern generated by applying an electron beam to a spectacle, the crystal orientation and crystal system of that point can be obtained, and high-speed processing of 10 to 30 points per second can be performed. Therefore, the grain boundary structure and crystal grain distribution can be analyzed.

Further, as a result of the analysis by the EBSP method, the longer the heat treatment time, the proportion within <30> from <111> from the cross-sectional crystal distribution diagram within 30 ° from each crystal direction of <001><101><111> Is known to increase.
Such a mechanism for preventing aluminum corrosion is currently under investigation. For such a corrosion inhibiting effect, a cross-sectional crystal distribution diagram within 30 ° from each crystal direction of <001>, <101> and <111>. The ratio within 30 ° from <111> is preferably 0.7% or more, more preferably 2% or more. When recognizing this crystal grain, a reference orientation difference is designated, and if the orientation difference between adjacent pixels is larger than the designated reference, the crystal grains are different.

Furthermore, it has been found that the ratio of the Σ1 value to the total number of grain boundaries from the cross-sectional crystal distribution diagram is lower as the heat treatment time is longer.
Σ1 is 15 to 180 ° (with an angle (orientation difference) between adjacent crystal grains, the crystal lattice fits at one point intervals while being aligned with the adjacent crystal grains, that is, Σ3 is three point intervals The crystal lattice fits and Σ5 means that the crystal lattice fits at an interval of 5 points, and among 15 to 180 °, the Σ value that does not match any integer multiple has a large tilt angle (random) It is defined as a grain boundary.

  The decrease in Σ1 that is a small-angle grain boundary as the heat treatment time is increased is considered to be due to the recrystallization and disappearance of the small-angle grain boundary due to the heat treatment. The ratio of the Σ1 value to the total number of grain boundaries is preferably 62.7% or less, and more preferably 60.1% or less.

  For example, by applying a heat treatment at a temperature of 240 ° C. or higher to an aluminum foil specified in JIS H4160, the average crystal grain size becomes 11.5 μm or more, and each of <001> <101> <111> The ratio within 30 ° from <111> from the cross-sectional crystal distribution map within 30 ° from the crystal direction is 0.7% or more, and the ratio of the Σ1 value to the total grain boundary number from the cross-sectional grain distribution map is 62.7. % Or less has been confirmed.

  Hereinafter, the present invention will be described based on specific examples, but it is needless to say that the present invention is not limited to these examples.

[1] First Example (Example 1-1)
In producing the laminate film type secondary battery shown in FIGS. 3 and 4, first, the negative electrode 34 was produced by the following method.
That is, 94 parts by weight of JEF Chemical graphite powder (MESOPHASE FINE CARBON GRAPHITE POWDER), 1 part by weight of Showa Denko's fibrous graphite powder (VGCF) and 5 parts by weight of polyvinylidene fluoride (PVDF) as a binder are mixed. Thus, a negative electrode mixture was prepared and dispersed in N-methylpyrrolidone serving as a solvent to obtain a paste slurry.

Next, as the negative electrode current collector 34A, a 10 μm-thick strip-shaped copper foil was used. The negative electrode mixture slurry obtained as described above was applied onto the negative electrode current collector, dried, and then compression molded at a predetermined pressure. A strip-shaped negative electrode 34 was produced as the negative electrode active material layer 34B.
Subsequently, the negative electrode lead 32 was attached to the negative electrode current collector 34 </ b> A of the negative electrode 34.

On the other hand, the positive electrode 33 was produced by the following method.
That is, 0.5 mol of lithium carbonate and 1 mol of cobalt carbonate were mixed, and the mixture was calcined in air at 880 ° C. for 5 hours.
As a result of X-ray diffraction measurement of the obtained material, a peak that closely coincided with the peak of LiCoO ₂ registered in the JCPDS file was confirmed.

The obtained LiCoO ₂ was pulverized to obtain a powder having an average particle size of 13 μm.
Next, 95 parts by weight of this powder, 2 parts by weight of Lion Corporation Ketjen Black (specific surface area: 800 m ² / g) as a conductive agent, and 3 parts by weight of polyvinylidene fluoride as a binder were mixed. A positive electrode mixture was prepared and similarly dispersed in N-methylpyrrolidone to obtain a paste slurry.

Next, a strip-shaped aluminum foil having a thickness of 20 μm was used as the positive electrode current collector 33A, and the positive electrode mixture slurry obtained as described above was applied thereon and dried, followed by compression molding to form a positive electrode active material layer A belt-like positive electrode 33 was prepared as 33B. Subsequently, the positive electrode lead 31 was attached to the current collector 31 </ b> A of the positive electrode 33.
In addition, as this positive electrode lead 31, it is 350 degreeC with the temperature increase rate from room temperature to about 4 degrees / min. After being heated up to this temperature, it was heated at this temperature for 7 hours, and then subjected to a heat treatment for cooling to a room temperature environment at a temperature drop rate of about 4 ° / min.

The separator 35 is polyethylene made of Tonen Chemical having a thickness of 12 μm, and the positive electrode 33 and the negative electrode 34 obtained above are laminated through the separator 35 and wound flatly to attach a protective tape 37 to the outermost periphery. A wound electrode body 30 was produced.
And the obtained wound electrode body 30 was inserted in the exterior member 40 which consists of a laminate film. At this time, an adhesive film 41 was inserted between the positive electrode lead 31 and the negative electrode lead 32 and the laminate exterior member 40.

The electrolyte layer 36 has a mass ratio of ethylene carbonate (EC): propylene carbonate (PC): diethyl carbonate (DEC): vinyl ethyl carbonate (VEC) of 20: 18: 60: 1: 1 as a non-aqueous solvent. The electrolyte was adjusted so that lithium hexafluorophosphate (LiPF ₆ ) was 0.9 mol / kg as an electrolyte salt.

After injecting this electrolytic solution into the laminate outer member 40 containing the wound electrode body 30, the battery of this example was obtained by sealing under reduced pressure at the top seal portion. In addition, the width | variety of the top seal part was 2.5 mm.
Then, the battery was molded by pressing at a pressure of 1 N / cm ² for 3 minutes in an environment of 80 ° C.

(Example 1-2)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment temperature of the aluminum material used as the positive electrode lead 31 was set to 430 ° C.

(Example 1-3)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment temperature of the aluminum material was 480 ° C.

(Example 1-4)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment temperature of the aluminum material was 300 ° C.

(Example 1-5)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment temperature of the aluminum material was 260 ° C.

(Example 1-6)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment temperature of the aluminum material was 240 ° C.

(Example 1-7)
The same operation as in Example 1-1 except that instead of the aluminum O material, an aluminum H material made of Japanese foil (equivalent to AlN99H-H18 defined in JIS H4170) was used as the positive electrode lead 31. Was repeated to obtain the battery of this example.

(Comparative Example 1-1)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment temperature of the aluminum material used as the positive electrode lead 31 was set to 130 ° C.

(Comparative Example 1-2)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the aluminum O material was used as the positive electrode lead 31 without heat treatment.

(Comparative Example 1-3)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the aluminum H material was used as the positive electrode lead 31 without heat treatment.

(Reliability evaluation)
For each battery of the above examples and comparative examples, after performing constant-current low-voltage charging in an atmosphere of 23 ° C. under conditions of an upper limit voltage of 4.2 V, a current of 1 C, and 3 hours, a temperature of 60 ° C. and a humidity of 90 % For 1 month, and the presence or absence of liquid leakage from the positive electrode lead 11 of each battery was visually confirmed.
The liquid leakage rate (%) was calculated by (number of leaked batteries) / (number of evaluated batteries) × 100. If this value is high, it means a battery with low reliability. The results are shown in Table 1.

  As apparent from the results in Table 1, it was confirmed that leakage of the electrolyte solution can be prevented by setting the heat treatment temperature of the positive electrode lead 31 to 240 ° C. or higher.

[2] Second Example (Example 2-1)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment time of the aluminum material used as the positive electrode lead 31 was set to 24 hours.

(Example 2-2)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment time of the aluminum material was 1 hour.

(Example 2-3)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment time of the aluminum material was changed to 0.5 hour (30 minutes).

(Example 2-4)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment time of the aluminum material was changed to 0.1 hour (6 minutes).

(Example 2-5)
A battery of this example was obtained by repeating the same operation as in Example 1-1 except that the heat treatment time of the aluminum material was changed to 0.01 hour (36 seconds).

(Reliability evaluation)
The presence or absence of leakage from the positive electrode lead 31 in each battery of the above example was investigated by the same method as described above, and the reliability of each battery was evaluated. The results are shown in Table 2.

  As is clear from the results in Table 2, it was confirmed that the electrolyte solution could be prevented from leaking by heat-treating the positive electrode lead 31 for 0.1 hour or longer.

[3] Third Example For the purpose of investigating the physical properties of the positive electrode lead according to the first and second examples, the above Examples 1-1, 2-1, 2-2, 2-3, 2-4, 2 -5, and each positive electrode lead of Comparative Example 1-2, using a FB-2000A type FIB apparatus manufactured by Hitachi, Ltd., the cross-sectional shape was formed by FIB processing, and the cross-sectional structure was analyzed by the EBSP method. <001><101><111> From each crystal direction of <001><101><111> The ratio within 30 ° from <111> from the cross-sectional crystal distribution map, and the total grain boundary from the cross-sectional crystal distribution map The ratio of the Σ1 value to the number was determined. The results are shown in Table 3. In Table 3, the liquid leakage rates obtained in the first and second examples are also shown.

As is clear from the results in Table 3, the longer the heat treatment time at 350 ° C., the larger the crystal grain size, compared to the O material not subjected to heat treatment (Comparative Example 1-2). It was confirmed that the ratio within 30 ° from <111> of the above increased, and that the ratio of the Σ1 value to the total number of grain boundaries from the cross-sectional crystal distribution diagram decreased.
In order to suppress the leakage of the electrolyte, at least the average particle diameter of the crystal particles is 11.5 μm or more, the ratio within 30 ° from <111> is 0.7% or more, and the total number of grain boundaries It is necessary to set the ratio of Σ1 value to 62.7% or less, and in order to further ensure the effect of preventing leakage, 12.0 μm or more, 2.0% or more, and 60.1% or less, respectively. It turned out to be desirable.

[4] Fourth Example (Example 4-1)
As an electrolyte salt, 0.45 mol / kg of cyclic imide salt (1,3-perfluoropropane disulfonylimide lithium) represented by chemical formula (2) and 0.45 mol / L of lithium hexafluorophosphate were mixed. A battery of this example was obtained by repeating the same operation as in Example 1-1 except that it was used.

(Example 4-2)
As an electrolyte salt, lithium bis (trifluoromethanesulfone) imide (LiN (CF ₃ SO ₂ ) ₂ ) 0.45 mol / kg, which is a chain imide salt, and lithium hexafluorophosphate 0.45 mol / L are mixed. The battery of this example was obtained by repeating the same operation as in Example 1-1 except that it was used.

(Comparative Example 4-1)
A battery of this example was obtained by repeating the same operation as in Example 5-1, except that the heat treatment temperature of the aluminum material used as the positive electrode lead 31 was set to 130 ° C.

(Comparative Example 4-2)
A battery of this example was obtained by repeating the same operation as in Example 5-2 except that the heat treatment temperature of the aluminum material used as the positive electrode lead 31 was set to 130 ° C.

(Reliability evaluation)
The presence or absence of leakage from the positive electrode lead 31 in each battery of the above example was investigated by the same method as described above, and the reliability of each battery was evaluated. The results are shown in Table 4.

  As is clear from the results in Table 4, even when an electrolytic solution to which a cyclic imide salt or a chain imide was added was used, no leakage occurred when heat treatment was performed, and the effect of improving reliability was confirmed.

[5] Fifth Example (Example 5-1)
In producing the cylindrical secondary battery shown in FIGS. 1 and 2, first, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) were mixed at a molar ratio of 0.5: 1, Were calcined at 890 ° C. for 5 hours to obtain lithium-cobalt composite oxide (LiCoO ₂ ). For LiCoO ₂ obtained was subjected to X-ray diffraction, it was confirmed that good agreement with the JCPDS (Joint Committee of Power Diffraction Standard ) LiCoO 2 of the peak, which is registered in the file.
Subsequently, the lithium / cobalt composite oxide was pulverized into a powder having an average particle size of 10 μm, and this was used as a positive electrode active material.

Next, 95 parts by mass of LiCoO ₂ and 5 parts by mass of Li ₂ CO ₃ powder are mixed, 91 parts by mass of the mixture, 6 parts by mass of artificial graphite (KS-15 manufactured by Lonza) as a conductive material, and a binder. And 3 parts by mass of polyvinylidene fluoride were mixed and dispersed in N-methyl-2-pyrrolidone as a solvent to obtain a positive electrode mixture slurry.
Next, it is made of Japanese foil aluminum O material, heated for 7 hours at a temperature of 350 ° C., then cooled to 100 ° C. over 1 hour, and then subjected to a heat treatment for cooling in a room temperature environment to a 20 μm-thick strip shape The positive electrode current collector 21 </ b> A was uniformly coated on both surfaces and dried, followed by compression molding to form the positive electrode active material layer 21 </ b> B, thereby producing the positive electrode 21. Then, an aluminum positive electrode lead 25 that was similarly heat-treated was attached to one end of the positive electrode current collector 21A.

On the other hand, the negative electrode active material was synthesized using a mechanochemical reaction, and composition analysis was performed on the obtained negative electrode active material powder. As a result, 50% Sn-29.4% Co-19.6% C (mass ratio) Met.
The above analysis results are obtained by measuring the carbon content with a carbon / sulfur analyzer and measuring the content of other elements by ICP (Inductive Coupled Plasma) emission analysis.

  80 parts by mass of the obtained negative electrode active material powder, 14 parts by mass of artificial graphite (KS-15 made by Lonza), 1 part by mass of acetylene black, and 5 parts by mass of polyvinylidene fluoride as a binder were mixed. The negative electrode 22 was produced by dispersing in N-methyl-2-pyrrolidone as a solvent and coating the negative electrode current collector 22A to form the negative electrode active material layer 22B. Subsequently, a negative electrode lead 26 made of nickel was attached to one end of the negative electrode current collector 22A.

  After preparing the positive electrode 21 and the negative electrode 22, a polyethylene separator 23 having a thickness of 25 μm is prepared, and the negative electrode 22, the separator 23, the positive electrode 21, and the separator 23 are laminated in this order, and this laminate is wound many times in a spiral. The wound electrode part 20 was produced by fixing the winding end part using an adhesive tape.

After the wound electrode body 20 is fabricated, the wound electrode body 20 is sandwiched between a pair of insulating plates 12 and 13, the negative electrode lead 26 is welded to the nickel-plated steel battery can 11, and the positive electrode lead 25 is a safety valve mechanism. 15 and the wound electrode body 20 was accommodated in the battery can 11.
And the electrolyte solution was inject | poured by the pressure_reduction | reduced_pressure method inside the battery can 11, and the cylindrical secondary battery of diameter 18mm and height 65mm was produced.

  The electrolyte was prepared by mixing 20% by mass of 4-fluoro-1,3-dioxolan-2-one (FEC), 20% by mass of ethylene carbonate, and 60% by mass of dimethyl carbonate as a solvent. As the electrolyte salt, cyclic imide salt (1,3-perfluoropropane disulfonylimide lithium) 0.5 mol / L shown in chemical formula (2) and lithium hexafluorophosphate 0.5 mol / L And used in combination.

(Example 5-2)
By repeating the same operation as in Example 5-1, except that the addition amounts of the cyclic imide salt and lithium hexafluorophosphate as the electrolyte salt were 0.7 mol / L and 0.3 mol / L, respectively. A battery of this example was obtained.

(Example 5-3)
By repeating the same operation as in Example 5-1, except that only 1 mol / L of the cyclic imide salt was added without adding lithium hexafluorophosphate as an electrolyte salt, the battery of this example was manufactured. Obtained.

(Example 5-4)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that only 2 mol / L of the cyclic imide salt was added without adding lithium hexafluorophosphate as the electrolyte salt. Obtained.

(Example 5-5)
By repeating the same operation as in Example 5-1, except that the addition amounts of the cyclic imide salt and lithium hexafluorophosphate as the electrolyte salt were 0.3 mol / L and 0.7 mol / L, respectively. A battery of this example was obtained.

(Example 5-6)
By repeating the same operation as in Example 5-1, except that the addition amounts of the cyclic imide salt and lithium hexafluorophosphate as the electrolyte salt were 0.05 mol / L and 0.95 mol / L, respectively. A battery of this example was obtained. By repeating, the battery of this example was obtained.

(Example 5-7)
By repeating the same operation as in Example 5-1, except that the addition amounts of the cyclic imide salt and lithium hexafluorophosphate as the electrolyte salt were 0.01 mol / L and 0.99 mol / L, respectively. A battery of this example was obtained.

(Example 5-8)
By repeating the same operation as in Example 5-1, except that only 1 mol / L of lithium hexafluorophosphate was added as the electrolyte salt without adding the cyclic imide salt, the battery of this example was obtained. Obtained.

(Comparative Example 5-1)
A battery of this example was obtained by repeating the same operation as in Example 5-1, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 5-2)
By repeating the same operation as Comparative Example 5-1, except that only 1 mol / L of the cyclic imide salt was added without adding lithium hexafluorophosphate as an electrolyte salt, the battery of this example was manufactured. Obtained.

(Comparative Example 5-3)
By repeating the same operation as Comparative Example 5-1, except that only 1 mol / L of lithium hexafluorophosphate was added as the electrolyte salt without adding the cyclic imide salt, the battery of this example was obtained. Obtained.

(Comparative Example 5-4)
As the positive electrode current collector 21A, in place of the heat-treated aluminum O material, an aluminum H material made of Japanese foil (equivalent to AlN99H-H18 defined in JIS H4170) was used as it was without heat treatment. The battery of this example was obtained by repeating the same operation as in Example 5-3.

(Discharge capacity evaluation)
Each battery of the above examples and comparative examples was subjected to constant current constant voltage charge of 2500 mA up to an upper limit voltage of 4.2 V at 25 ° C. and 50 ° C., respectively, and then constant current discharge of 2000 mA was applied to a final voltage of 2.6 V The discharge capacity maintenance rate (%) at the 150th cycle when the discharge capacity at the first cycle was set to 100 was determined.
The results are shown in Table 5.

  As is apparent from the results in Table 5, the discharge capacity retention rate is improved by heat-treating the aluminum positive electrode current collector, and the discharge capacity retention rate is also improved by using a cyclic imide salt as the electrolyte salt. It was confirmed that Further, the effect is improved as the amount of the cyclic imide salt added increases, but when it is excessively added, a tendency to decrease is observed, and the peak seems to be in the vicinity of 1 mol / L.

[6] Sixth Example (Example 6-1)
The same operation as in Example 5-3 (electrolyte salt: cyclic imide salt 1 mol / L, heat treatment temperature 350 ° C.) is repeated except that the heat treatment temperature of the aluminum material used as the positive electrode current collector 21A is 430 ° C. Thus, the battery of this example was obtained.

(Example 6-2)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment temperature of the aluminum material was 480 ° C.

(Example 6-3)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment temperature of the aluminum material was 300 ° C.

(Example 6-4)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment temperature of the aluminum material was 260 ° C.

(Example 6-5)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment temperature of the aluminum material was 240 ° C.

(Example 6-6)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment temperature of the aluminum material was 520 ° C.

(Comparative Example 6-1)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment temperature of the aluminum material was 130 ° C.

(Discharge capacity evaluation)
The discharge capacity maintenance rate (%) was determined for each battery of the above Examples and Comparative Examples by conducting the same test as in Example 5 above. The results are shown in Table 6 together with the data of Example 5-3.

  From Table 6, in the case of the treatment for 7 hours, the aluminum material for the positive electrode current collector is subjected to a heat treatment at 240 ° C. or more, and the effect of improving the discharge capacity retention rate can be obtained, and reaches a peak at around 350 ° C. On the other hand, when it exceeded 480 degreeC, the tendency for an effect to reduce on the contrary was recognized.

[7] Seventh Example (Example 7-1)
The same operation as in Example 5-3 (electrolyte salt: cyclic imide salt 1 mol / L, heat treatment temperature: 350 ° C.) is repeated except that the heat treatment time of the aluminum material used as the positive electrode current collector 21A is 24 hours. Thus, the battery of this example was obtained.

(Example 7-2)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment time of the aluminum material was 1 hour.

(Example 7-3)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment time of the aluminum material was 0.5 hour (30 minutes).

(Example 7-4)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment time of the aluminum material was 0.1 hour (6 minutes).

(Example 7-5)
A battery of this example was obtained by repeating the same operation as in Example 5-3 except that the heat treatment time of the aluminum material was 0.01 hour (36 seconds).

(Discharge capacity evaluation)
The discharge capacity maintenance rate (%) was obtained by performing the same test as in Example 5 for each battery of the above example. The results are shown in Table 7 together with the data of Example 5-3.

  As can be seen from Table 7, in the case of 350 ° C. treatment, it was confirmed that the discharge capacity retention rate improved as the heat treatment time applied to the aluminum material for the positive electrode current collector was increased.

[8] Eighth Example (Example 8-1)
Regarding the negative electrode 22, 90 parts by mass of artificial graphite (KS-75 manufactured by Lonza) was mixed with 10 parts by mass of polyvinylidene fluoride as a binder, and dispersed in N-methyl-2-pyrrolidone as a solvent, thereby collecting the negative electrode The negative electrode active material layer 22B is applied to the body 22A, and 5% by mass of propylene carbonate, 33% by mass of ethylene carbonate, 2% by mass of vinylene carbonate, and 60% by mass of dimethyl carbonate are used as a nonaqueous solvent for the electrolytic solution. A battery of this example was obtained by repeating the same operation as in Example 5-1 except that the mixture of was used.

(Example 8-2)
By repeating the same operation as Example 8-1 except that the addition amounts of the cyclic imide salt and lithium hexafluorophosphate as the electrolyte salt were 0.7 mol / L and 0.3 mol / L, respectively. A battery of this example was obtained.

(Example 8-3)
A battery of this example was obtained by repeating the same operation as Example 8-1 except that only 1 mol / L of the cyclic imide salt was added as the electrolyte salt.

(Example 8-4)
A battery of this example was obtained by repeating the same operation as Example 8-1 except that only 2 mol / L of the cyclic imide salt was added as the electrolyte salt.

(Example 8-5)
As the electrolyte salt, the same operations as in Example 8-1 were repeated except that the addition amounts of the cyclic imide salt and lithium hexafluorophosphate were 0.3 mol / L and 0.7 mol / L, respectively.

(Example 8-6)
By repeating the same operation as Example 8-1 except that the addition amount of the cyclic imide salt and lithium hexafluorophosphate as the electrolyte salt was 0.05 mol / L and 0.95 mol / L, respectively. A battery of this example was obtained. By repeating, the battery of this example was obtained.

(Example 8-7)
By repeating the same operations as in Example 8-1 except that the addition amounts of the cyclic imide salt and lithium hexafluorophosphate as the electrolyte salt were 0.01 mol / L and 0.99 mol / L, respectively. A battery of this example was obtained.

(Example 8-8)
A battery of this example was obtained by repeating the same operation as in Example 5-1, except that only 1 mol / L of lithium hexafluorophosphate was added as the electrolyte salt.

(Comparative Example 8-1)
A battery of this example was obtained by repeating the same operation as in Example 8-8, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 8-2)
A battery of this example was obtained by repeating the same operation as in Comparative Example 8-1, except that only 1 mol / L of the cyclic imide salt was added as the electrolyte salt.

(Comparative Example 8-3)
As the positive electrode current collector 21A, in place of the heat-treated aluminum O material, an aluminum H material made of Japanese foil (equivalent to AlN99H-H18 defined in JIS H4170) was used as it was without heat treatment. The battery of this example was obtained by repeating the same operation as in Example 8-8.

(Comparative Example 8-4)
A battery of this example was obtained by repeating the same operation as in Comparative Example 8-3 except that only 1 mol / L of the cyclic imide salt was added as the electrolyte salt.

(Discharge capacity evaluation)
The discharge capacity maintenance rate (%) was determined for each battery of the above Examples and Comparative Examples by conducting the same test as in Example 5 above. The results are shown in Table 8.

  As is apparent from Table 8, even when the composition of the negative electrode active material and the nonaqueous solvent is different, the discharge capacity retention rate is improved by the same heat treatment, and the discharge is achieved by using a cyclic imide salt as the electrolyte salt. It was confirmed that the capacity maintenance rate was improved.

[9] Ninth Example (Example 9-1)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Fe-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-2)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Mg-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-3)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Ti-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-4)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% V-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-5)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Cr-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-6)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Mn-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-7)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Ni-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-8)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Cu-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-9)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Zn-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-10)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Ga-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-11)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Zr-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Examples 9-12)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Nb-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-13)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Mo-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Examples 9-14)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Ag-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Examples 9-15)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% In-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-16)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Ce-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Examples 9-17)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Hf-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Examples 9-18)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Ta-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Examples 9-19)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% W-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-20)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Bi-19.6% C (mass ratio) was used as the negative electrode active material. Got.

(Example 9-21)
By repeating the same operation as in Example 5-1, except that 49% Sn-23.4% Co-5.0In-19.6% C (mass ratio) was used as the negative electrode active material, The battery of this example was obtained.

(Example 9-22)
The same operation as in Example 5-1, except that 49% Sn-23.4% Co-5.0In-2.0Ti-19.6% C (mass ratio) was used as the negative electrode active material. By repeating, the battery of this example was obtained.

(Examples 9-23)
The same operation as in Example 5-1 is repeated except that 49% Sn-3.9% Si-29.4% Co-19.6% C (mass ratio) is used as the negative electrode active material. Thus, the battery of this example was obtained.

(Comparative Example 9-1)
A battery of this example was obtained by repeating the same operation as Example 9-1 except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-2)
A battery of this example was obtained by repeating the same operation as in Example 9-2, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-3)
A battery of this example was obtained by repeating the same operation as in Example 9-2, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-4)
A battery of this example was obtained by repeating the same operation as in Example 9-4, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-5)
A battery of this example was obtained by repeating the same operation as Example 9-5 except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-6)
A battery of this example was obtained by repeating the same operation as in Example 9-6, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-7)
A battery of this example was obtained by repeating the same operation as in Example 9-7, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-8)
A battery of this example was obtained by repeating the same operation as in Example 9-8, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-9)
A battery of this example was obtained by repeating the same operation as in Example 9-9, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-10)
A battery of this example was obtained by repeating the same operation as in Example 9-10, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-11)
A battery of this example was obtained by repeating the same operation as in Example 9-11, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-12)
A battery of this example was obtained by repeating the same operation as Example 9-12, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-13)
A battery of this example was obtained by repeating the same operation as in Example 9-13, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-14)
A battery of this example was obtained by repeating the same operation as in Example 9-14, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-15)
A battery of this example was obtained by repeating the same operation as Example 9-15 except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-16)
A battery of this example was obtained by repeating the same operation as in Example 9-16, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-17)
A battery of this example was obtained by repeating the same operation as in Example 9-17, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-18)
A battery of this example was obtained by repeating the same operation as in Example 9-18, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-19)
A battery of this example was obtained by repeating the same operation as in Example 9-19, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-20)
A battery of this example was obtained by repeating the same operation as in Example 9-20, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-21)
A battery of this example was obtained by repeating the same operation as in Example 9-21, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-22)
A battery of this example was obtained by repeating the same operations as in Examples 9-22 except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 9-23)
A battery of this example was obtained by repeating the same operation as in Examples 9-23 except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Discharge capacity evaluation)
The discharge capacity maintenance rate (%) was determined for each battery of the above Examples and Comparative Examples by conducting the same test as in Example 5 above. The results are shown in Table 9 and Table 10 together with the data of Example 5-1 and Comparative Example 5-1.

[10] Tenth Example (Example 10-1)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Co-19.6% B (mass ratio) was used as the negative electrode active material. Got.

(Example 10-2)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Co-19.6% Al (mass ratio) was used as the negative electrode active material. Got.

(Example 10-3)
The battery of this example was obtained by repeating the same operation as in Example 5-1, except that 50% Sn-29.4% Co-19.6% P (mass ratio) was used as the negative electrode active material. Got.

(Comparative Example 10-1)
A battery of this example was obtained by repeating the same operation as in Example 10-1, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 10-2)
A battery of this example was obtained by repeating the same operation as Example 10-2 except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Comparative Example 10-3)
A battery of this example was obtained by repeating the same operation as in Example 9-2, except that the aluminum O material was used as it was without being heat-treated as the positive electrode current collector 21A.

(Discharge capacity evaluation)
The discharge capacity maintenance rate (%) was determined for each battery of the above Examples and Comparative Examples by conducting the same test as in Example 5 above. The results are shown in Table 11 together with the data of Example 5-1 and Comparative Example 5-1.

[11] Eleventh Example (Example 11-1)
The battery of this example was obtained by repeating the same operation as in Example 8-1 except that the amount of vinylene carbonate contained in the nonaqueous solvent of the electrolytic solution was 0 and ethylene carbonate was increased by that amount. It was.

(Example 11-2)
By repeating the same operation as in Example 8-1 except that the amount of vinylene carbonate contained in the nonaqueous solvent of the electrolytic solution was 0.1% by mass and the amount of ethylene carbonate was increased by that amount, this example was repeated. Battery was obtained.

(Example 11-3)
By repeating the same operation as in Example 8-1 except that the amount of vinylene carbonate contained in the non-aqueous solvent of the electrolytic solution was 0.05% by mass and the amount of ethylene carbonate was increased by this amount, this example was repeated. Battery was obtained.

(Example 11-4)
The battery of this example was obtained by repeating the same operation as in Example 8-1 except that the amount of vinylene carbonate contained in the nonaqueous solvent of the electrolytic solution was 10% by mass, and ethylene carbonate was reduced accordingly. Got.

(Example 11-5)
The battery of this example was obtained by repeating the same operation as in Example 8-1 except that the amount of vinylene carbonate contained in the non-aqueous solvent of the electrolytic solution was 20% by mass and ethylene carbonate was reduced accordingly. Got.

(Example 11-6)
A battery of this example was obtained by repeating the same operation as in Example 8-1 except that vinylethylene carbonate was mixed instead of vinylene carbonate contained in the nonaqueous solvent of the electrolytic solution.

(Example 11-7)
By repeating the same operation as in Example 11-6 except that the amount of vinyl ethylene carbonate contained in the non-aqueous solvent of the electrolytic solution was 0.1% by mass and the amount of ethylene carbonate was increased by that amount, An example battery was obtained.

(Example 11-8)
By repeating the same operation as in Example 11-6 except that the amount of vinyl ethylene carbonate contained in the non-aqueous solvent of the electrolytic solution was 0.05% by mass and the amount of ethylene carbonate was increased by that amount, An example battery was obtained.

(Example 11-9)
By repeating the same operation as in Example 11-6 except that the amount of vinyl ethylene carbonate contained in the non-aqueous solvent of the electrolytic solution was 10% by mass and the amount of ethylene carbonate was reduced accordingly, A battery was obtained.

(Example 11-10)
By repeating the same operation as in Example 11-6 except that the amount of vinyl ethylene carbonate contained in the non-aqueous solvent of the electrolytic solution was 20% by mass and the amount of ethylene carbonate was reduced by that amount, A battery was obtained.

(Example 11-11)
By repeating the same operation as in Example 8-1 except that 1% by mass of propane sultone was mixed instead of vinylene carbonate contained in the non-aqueous solvent of the electrolytic solution and ethylene carbonate was increased by that amount, An example battery was obtained.

(Examples 11-12)
The battery of this example was obtained by repeating the same operation as in Example 11-11 except that the amount of propane sultone contained in the nonaqueous solvent of the electrolyte was 3% by mass and the amount of ethylene carbonate was reduced accordingly. Got.

(Examples 11-13)
The battery of this example was obtained by repeating the same operation as in Example 11-11 except that the amount of propane sultone contained in the nonaqueous solvent of the electrolytic solution was 5% by mass and the amount of ethylene carbonate was reduced by that amount. Got.

(Examples 11-14)
By repeating the same operation as in Example 11-11 except that the amount of propane sultone contained in the nonaqueous solvent of the electrolytic solution was 0.05% by mass and the amount of ethylene carbonate was increased by that amount, this example was repeated. Battery was obtained.

(Examples 11-15)
By repeating the same operation as in Example 11-11 except that the amount of propane sultone contained in the non-aqueous solvent of the electrolytic solution was 0.01% by mass and the amount of ethylene carbonate was increased accordingly, this example was repeated. Battery was obtained.

(Examples 11-16)
By repeating the same operation as in Example 8-1 except that 1% by mass of propene sultone was mixed instead of vinylene carbonate contained in the nonaqueous solvent of the electrolytic solution and ethylene carbonate was increased by that amount, An example battery was obtained.

(Examples 11-17)
The battery of this example was obtained by repeating the same operations as in Examples 11-16 except that the amount of propene sultone contained in the nonaqueous solvent of the electrolytic solution was 3% by mass and the amount of ethylene carbonate was reduced accordingly. Got.

(Examples 11-18)
By repeating the same operation as in the above Example 11-16 except that the amount of propellon contained in the nonaqueous solvent of the electrolytic solution was 5% by mass and the amount of ethylene carbonate was reduced by that amount, A battery was obtained.

(Examples 11-19)
By repeating the same operation as in Example 11-16 except that the amount of propene sultone contained in the nonaqueous solvent of the electrolytic solution was 0.05% by mass and the amount of ethylene carbonate was increased by that amount, this example was repeated. Battery was obtained.

(Examples 11-20)
By repeating the same operation as in Example 11-16 except that the amount of propane sultone contained in the non-aqueous solvent of the electrolytic solution was 0.01% by mass and the amount of ethylene carbonate was increased accordingly, this example was repeated. Battery was obtained.

(Discharge capacity evaluation)
The discharge capacity maintenance rate (%) was determined for each battery of the above Examples and Comparative Examples by conducting the same test as in Example 5 above. The results are shown in Table 12 together with the data of Example 8-1.

As is apparent from the results shown in Table 11, the effect of improving the discharge capacity retention rate was recognized by mixing an additive such as vinylene carbonate, vinylethyl carbonate, propene sultone, or propane sultone with the nonaqueous solvent of the electrolytic solution. It was.
In addition, the effect improves as the mixing amount of these additives increases. However, when added excessively, a tendency to decrease is recognized. The peak is around 2% by mass for vinylene carbonate and vinylethyl carbonate, propene sultone and propane. It seems that sultone is in the vicinity of 1% by mass.

It is sectional drawing which shows the structural example of a cylindrical secondary battery as embodiment of this invention. FIG. 2 is a partial enlarged cross-sectional view of a wound electrode body in the cylindrical secondary battery shown in FIG. 1. It is sectional drawing which shows the structural example of the laminate film type secondary battery as other embodiment of this invention. It is sectional drawing along the II line | wire of the winding electrode body in the laminate film type secondary battery shown in FIG. It is a cyclic voltammogram which shows the result of having investigated the influence of the heat processing on the reactivity of electrolyte solution and aluminum material. It is a cyclic voltammogram which shows the result of having investigated the influence of the heat processing on the reactivity of the electrolyte solution containing a cyclic imide salt, and an aluminum material. It is a graph which shows the cyclic voltammogram using the aluminum material which carried out file processing. It is a SIM observation image which shows the cross-sectional structure | tissue of heat processing O material. It is a SIM observation image which shows the cross-sectional structure | tissue of non-heat-processing O material. It is a SIM observation image which shows the cross-sectional structure | tissue of non-heat-processing H material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Battery can, 12, 13 ... Insulation board, 14 ... Battery cover, 15 ... Safety valve mechanism, 15A ... Disc board, 16 ... Heat sensitive resistance element, 17 ... Gasket, 20, 30 ... Winding electrode body, 21, 33 ... Positive electrode, 21A, 33A ... Positive electrode current collector, 21B, 33B ... Positive electrode active material layer, 22, 34 ... Negative electrode, 22A, 34A ... Negative electrode current collector, 22B, 34B ... Negative electrode active material layer, 23, 35 ... Separator 24 ... Center pin, 25, 31 ... Positive electrode lead, 26, 32 ... Negative electrode lead, 36 ... Electrolyte layer, 37 ... Protective tape, 40 ... Exterior member, 41 ... Adhesion film

Claims (24)

  A conductive member for a positive electrode comprising an aluminum material that has been heat-treated at a temperature of 240 ° C. or higher.   The conductive member for positive electrode according to claim 1, wherein the heat treatment time is 0.1 hour or more.   When the current value at a potential of 5 V in a cyclic voltammogram made of an aluminum material and having an aluminum O material as a working electrode is 1, the current value at a potential of 5 V with the aluminum material as a working electrode is 0.9 or less. A positive electrode conductive member.   When a current value at a potential of 5 V in a cyclic voltammogram made of an aluminum material and having an aluminum H material as a working electrode is 1, the current value at a potential of 5 V using the aluminum material as a working electrode is 0.5 or less. A positive electrode conductive member.   A conductive member for a positive electrode comprising an aluminum material, wherein the aluminum material has an average crystal grain size of 11.5 μm or more.   It consists of an aluminum material, and in the cross-sectional crystal distribution within 30 ° from each crystal direction of <001> <101> <111>, the proportion within 30 ° from <111> is 0.7% or more. A conductive member for a positive electrode characterized by the above.   A conductive member for a positive electrode comprising an aluminum material, wherein the ratio of the Σ1 value to the total number of grain boundaries of the aluminum material is 62.7% or less.   It is a positive electrode lead, The electrically conductive member for positive electrodes as described in any one of Claim 1, 3-7 characterized by the above-mentioned.   It is a positive electrode electrical power collector, The electrically conductive member for positive electrodes as described in any one of Claim 1, 3-7 characterized by the above-mentioned. A positive and negative electrode capable of electrochemically doping and undoping lithium;
An electrolyte composition interposed between the positive electrode and the negative electrode;
In a battery provided with an exterior member that accommodates these,
A battery characterized in that the positive electrode lead and / or the positive electrode current collector is made of an aluminum material that has been heat-treated at a temperature of 240 ° C. or higher. A positive and negative electrode capable of electrochemically doping and undoping lithium;
An electrolyte composition interposed between the positive electrode and the negative electrode;
In a battery provided with an exterior member that accommodates these,
When the positive electrode lead and / or the positive electrode current collector is made of an aluminum material and the current value at a potential of 5 V in a cyclic voltammogram using an aluminum O material as a working electrode is 1, the potential is 5 V using the aluminum material as a working electrode. The battery has a current value of 0.9 or less. A positive and negative electrode capable of electrochemically doping and undoping lithium;
An electrolyte composition interposed between the positive electrode and the negative electrode;
In a battery provided with an exterior member that accommodates these,
When the positive electrode lead and / or the positive electrode current collector is made of an aluminum material and the current value at a potential of 5 V in the cyclic voltammogram using the aluminum H material as the working electrode is 1, the potential is 5 V using the aluminum material as the working electrode. The battery has a current value of 0.5 or less. A positive and negative electrode capable of electrochemically doping and undoping lithium;
An electrolyte composition interposed between the positive electrode and the negative electrode;
In a battery provided with an exterior member that accommodates these,
A battery, wherein the positive electrode lead and / or the positive electrode current collector is made of an aluminum material, and the average crystal grain size of the aluminum material is 11.5 μm or more. A positive and negative electrode capable of electrochemically doping and undoping lithium;
An electrolyte composition interposed between the positive electrode and the negative electrode;
In a battery provided with an exterior member that accommodates these,
The positive electrode lead and / or the positive electrode current collector is made of an aluminum material, and in the aluminum material, the cross-sectional crystal distribution within 30 ° from each crystal direction of <001><101><111> is within 30 ° from <111>. A battery having a ratio of 0.7% or more. A positive and negative electrode capable of electrochemically doping and undoping lithium;
An electrolyte composition interposed between the positive electrode and the negative electrode;
In a battery provided with an exterior member that accommodates these,
A battery, wherein the positive electrode lead and / or the positive electrode current collector is made of an aluminum material, and the ratio of the Σ1 value to the total number of grain boundaries of the aluminum material is 62.7% or less.   The battery according to claim 10, wherein the heat treatment time is 0.1 hour or more. The battery according to claim 10, wherein the electrolyte composition contains a cyclic imide salt represented by the following chemical formula (1).

[R1 in the formula represents a linear or branched alkylene group having 2 to 5 carbon atoms, or a group in which at least a part of hydrogen thereof is substituted with fluorine. ]   The battery according to claim 11, wherein the content of the cyclic imide salt in the electrolyte composition is 0.01 to 2 mol / L.   11. The battery according to claim 10, wherein the electrolyte composition contains at least one selected from the group consisting of vinylene carbonate, vinyl ethyl carbonate, propene sultone, and propane sultone.   14. The battery according to claim 13, wherein the total content of the vinylene carbonate and / or vinyl ethyl carbonate with respect to the liquid in the electrolyte composition is 0.05 to 20% by mass ratio.   14. The battery according to claim 13, wherein a total content of the propene sultone and / or propane sultone with respect to the liquid in the electrolyte composition is 0.01 to 5% by mass ratio.   The battery according to claim 10, wherein the electrolyte composition contains lithium hexafluorophosphate.   The battery according to claim 10, wherein the negative electrode active material contained in the negative electrode is a carbon material. The negative electrode contains a negative electrode active material containing tin as a first constituent element, a second constituent element, and a third constituent element,
The second constituent element is cobalt (Co), iron (Fe), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu ), Zinc (Zn), gallium (Ga), zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), indium (In), cerium (Ce), hafnium (Hf), tantalum (Ta) ), Tungsten (W), bismuth (Bi) and silicon (Si), at least one element selected from the group consisting of
The third constituent element is at least one element selected from the group consisting of boron (B), carbon (C), aluminum (Al) and phosphorus (P);
The battery according to claim 10, wherein the electrolyte composition contains a cyclic imide salt represented by the following chemical formula (1) and 4-fluoro-1,3-dioxolan-2-one.

[R1 in the formula represents a linear or branched alkylene group having 2 to 5 carbon atoms, or a group in which at least a part of hydrogen thereof is substituted with fluorine. ]

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