JP2007173147A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-life nonaqueous electrolyte secondary battery capable of suppressing increase of resistance of the battery in using it at high temperatures and over a long time. <P>SOLUTION: This nonaqueous electrolyte secondary battery is provided with: a positive electrode containing a substance storing/releasing lithium as a constituent; a negative electrode containing a substance storing/releasing lithium as a constituent; and a nonaqueous electrolyte; and is characterized in that the nonaqueous electrolyte contains a compound represented by chemical formula (1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte secondary battery.

  Along with the rapid miniaturization and diversification of consumer mobile phones, portable devices and personal digital assistants, etc., the battery that is the power source is small, lightweight, high energy density, and repeatedly charged and discharged for a long time. There is a strong demand for the development of secondary batteries that can be realized. Among them, non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are the most promising and active as secondary batteries that satisfy these needs compared to lead batteries and nickel cadmium batteries that use aqueous electrolytes. Research has been conducted.

The positive electrode active material of the nonaqueous electrolyte secondary battery includes general formula Li _x such as titanium disulfide, vanadium pentoxide and molybdenum trioxide, lithium cobalt composite oxide, lithium nickel composite oxide and spinel type manganese oxide. Various compounds represented by MO ₂ (where M is one or more transition metals) have been studied. Among these, lithium cobalt composite oxide, lithium nickel composite oxide, spinel-type lithium manganese composite oxide, and the like can be charged and discharged at an extremely noble potential of 4 V (vs Li / Li ⁺ ) or more. As a result, a battery having a high discharge voltage can be realized.

  Various negative electrode active materials for non-aqueous electrolyte secondary batteries, such as metallic lithium, lithium alloys, and carbon materials capable of occluding / releasing lithium, have been studied. There is an advantage that a battery having a long life can be obtained and safety is high.

For the electrolyte of a non-aqueous electrolyte secondary battery, a supporting salt such as LiPF ₆ or LiBF ₄ is generally mixed with a mixed solvent of a high dielectric constant solvent such as ethylene carbonate or propylene carbonate and a low viscosity solvent such as dimethyl carbonate or diethyl carbonate. A dissolved electrolyte is used.

  In recent years, the demand for non-aqueous electrolyte secondary batteries as a power source for mobile bodies such as hybrid cars has been increasing, and it is necessary to further extend the service life of mobile phones for consumer use. As a method for improving battery life characteristics, it has been found that mixing a specific compound with a non-aqueous electrolyte is effective. For example, vinylene carbonate described in Patent Document 1 or 1,3-propane described in Patent Document 2 Sulton has been proposed.

However, even when these compounds are used as additives, the resistance of the battery increases when used at a high temperature for a long period of time, and the effect is not sufficient, and an additive capable of further improving the characteristics is desired. It was.
Japanese Patent Laid-Open No. 5-13088 JP-A-11-162551

  The invention according to claim 1 is a non-aqueous electrolyte secondary battery comprising a positive electrode comprising a substance that occludes / releases lithium, a negative electrode comprising a substance that occludes / releases lithium, and a non-aqueous electrolyte. And the said non-aqueous electrolyte contains the compound represented by Chemical formula (1), It is characterized by the above-mentioned.

（ここで、ｎは１〜３の整数であり、Ｒ１およびＲ２の少なくとも一方は炭素-炭素不飽和結合を含む鎖状または分岐鎖状の基であり、Ｒ３およびＲ４は水素原子、ハロゲンおよび置換基を有していても良い有機基からなる群の中の１種である。）
請求項２の発明は、請求項１において、前記化学式（１）記載の化合物がビス（ビニルスルホニル）メタンおよびビス（アリルスルホニル）メタンのうち少なくとも1種であることを特徴とする請求項１記載の非水電解質二次電池である。

(Where n is an integer of 1 to 3, at least one of R1 and R2 is a chain or branched chain group containing a carbon-carbon unsaturated bond, and R3 and R4 are hydrogen atoms, halogens, and substituents. It is one of the group consisting of organic groups that may have a group.)
The invention of claim 2 is characterized in that, in claim 1, the compound represented by the chemical formula (1) is at least one of bis (vinylsulfonyl) methane and bis (allylsulfonyl) methane. This is a non-aqueous electrolyte secondary battery.

  The invention according to claim 3 is a non-aqueous electrolyte secondary battery characterized in that a non-aqueous electrolyte secondary battery is produced by injecting a non-aqueous electrolyte containing a compound represented by the chemical formula (1) into the battery. It is a manufacturing method of a battery.

  According to the first aspect of the present invention, there is provided a non-aqueous electrolyte comprising: a positive electrode having a substance that occludes / releases lithium; a negative electrode having a substance that occludes / releases lithium; and a non-aqueous electrolyte. In the secondary battery, when the non-aqueous electrolyte contains the compound represented by the chemical formula (1), the increase in the resistance of the battery can be reduced even during high temperature and long-term use.

  According to the invention of claim 2, by using at least one of bis (vinylsulfonyl) methane and bis (allylsulfonyl) methane as the compound of the chemical formula (1), the resistance of the battery even at high temperature and for a long period of use. The rise can be particularly small.

  According to the invention of claim 3, a nonaqueous electrolyte secondary battery is produced by injecting a nonaqueous electrolyte containing a compound represented by the chemical formula (1) into the battery. This is a secondary battery manufacturing method, and the non-aqueous electrolyte secondary battery obtained by this manufacturing method can particularly reduce the increase in resistance of the battery even when used at a high temperature for a long time.

  The present invention is a non-aqueous electrolyte secondary battery comprising a positive electrode comprising a substance that occludes / releases lithium, a negative electrode comprising a substance that occludes / releases lithium, and a non-aqueous electrolyte. The non-aqueous electrolyte contains a compound represented by the chemical formula (1).

（ここで、ｎは１〜３の整数であり、Ｒ１およびＲ２の少なくとも一方は炭素-炭素不飽和結合を含む鎖状または分岐鎖状の基であり、Ｒ３およびＲ４は水素原子、ハロゲンおよび置換基を有していても良い有機基からなる群の中の１種である。）
ここで、化学式（１）で示される具体例としては、Ｒ１およびＲ２の少なくともいずれか一方がビニル基、アリル基、イソプロペニル基、２−プロピニル基、２−プロペニル基、２−ブテニル基、１，３−ブタジエニル基、２−ペンテニル基、２−ペンテン−４−イニル基などから選択される一価の不飽和基をもつ官能基である化合物を上げることができる。Ｒ３およびＲ４が水素原子の場合、例えばメチルスルホニルビニルスルホニルメタン、エチルスルホニルビニルスルホニルメタン、プロピルスルホニルビニルスルホニルメタン、メチルスルホニルアリルスルホニルエタン、エチルスルホニルアリルスルホニルエタン、プロピルスルホニルアリルスルホニルエタン、ビニルスルホニルフェニルスルホニルメタン、ビニルスルホニルフェニルスルホニルエタン、ビニルスルホニルフェニルスルホニルプロパン、アリルスルホニルフェニルスルホニルメタン、アリルスルホニルフェニルスルホニルエタン、アリルスルホニルフェニルスルホニルプロパン、イソプロペニルスルホニルフェニルスルホニルメタン、イソプロペニルスルホニルフェニルスルホニルエタン、イソプロペニルスルホニルフェニルスルホニルプロパン、ビス（ビニルスルホニル）メタン、ビス（アリルスルホニル）メタン、ビス（イソプロペニルスルホニル）メタン、ビス（ビニルスルホニル）エタン、ビス（アリルスルホニル）エタン、ビス（イソプロペニルスルホニル）エタン、ビス（ビニルスルホニル）プロパン、ビス（アリルスルホニル）プロパン、ビス（イソプロペニルスルホニル）プロパン、アリルスルホニルビニルスルホニルメタン、アリルスルホニルビニルスルホニルエタンおよびアルルスルホニルビニルスルホニルプロパン等があげられる。ここで、Ｒ３とＲ４に相当する部分は水素原子、ハロゲンおよび置換基を有していても良い有機基からなる群の中の１種である。また、これらを単独または混合して使用することができる。これらの中で特に好適なのは、化学式（１）においてＲ１とＲ２がともに炭素−炭素不飽和結合を有する鎖状または分岐鎖状の不飽和基であり、Ｒ３およびＲ４を水素原子としたときであり、特に、ビス（ビニルスルホニル）メタンまたはビス（アリルスルホニル）メタンを用いると特に電池の抵抗上昇を抑制する効果が高く、より好適である。これらの化合物を用いた場合に高温かつ長期使用時の電池抵抗上昇が抑制される理由は現時点で明らかではないが、本発明の化合物を用いることで、正極および負極に安定な被膜が形成し、非水電解質の分解を効果的に抑制していることが考えられる。

(Where n is an integer of 1 to 3, at least one of R1 and R2 is a chain or branched chain group containing a carbon-carbon unsaturated bond, and R3 and R4 are hydrogen atoms, halogens, and substituents. It is one of the group consisting of organic groups that may have a group.)
Here, as specific examples represented by the chemical formula (1), at least one of R1 and R2 is vinyl group, allyl group, isopropenyl group, 2-propynyl group, 2-propenyl group, 2-butenyl group, 1 , 3-butadienyl group, 2-pentenyl group, 2-pentene-4-ynyl group, and the like, a compound that is a functional group having a monovalent unsaturated group can be raised. When R3 and R4 are hydrogen atoms, for example, methylsulfonylvinylsulfonylmethane, ethylsulfonylvinylsulfonylmethane, propylsulfonylvinylsulfonylmethane, methylsulfonylallylsulfonylethane, ethylsulfonylallylsulfonylethane, propylsulfonylallylsulfonylethane, vinylsulfonylphenylsulfonyl Methane, vinylsulfonylphenylsulfonylethane, vinylsulfonylphenylsulfonylpropane, allylsulfonylphenylsulfonylmethane, allylsulfonylphenylsulfonylethane, allylsulfonylphenylsulfonylpropane, isopropenylsulfonylphenylsulfonylmethane, isopropenylsulfonylphenylsulfonylethane, isopropenylsulfonylphenol Rusulfonylpropane, bis (vinylsulfonyl) methane, bis (allylsulfonyl) methane, bis (isopropenylsulfonyl) methane, bis (vinylsulfonyl) ethane, bis (allylsulfonyl) ethane, bis (isopropenylsulfonyl) ethane, bis ( Vinylsulfonyl) propane, bis (allylsulfonyl) propane, bis (isopropenylsulfonyl) propane, allylsulfonylvinylsulfonylmethane, allylsulfonylvinylsulfonylethane and allylsulfonylvinylsulfonylpropane. Here, the portion corresponding to R3 and R4 is one of the group consisting of a hydrogen atom, a halogen, and an organic group which may have a substituent. Moreover, these can be used individually or in mixture. Particularly preferred among these is when R1 and R2 in the chemical formula (1) are both chain-like or branched-chain unsaturated groups having a carbon-carbon unsaturated bond, and R3 and R4 are hydrogen atoms. In particular, when bis (vinylsulfonyl) methane or bis (allylsulfonyl) methane is used, the effect of suppressing an increase in battery resistance is particularly high, which is more preferable. The reason why the increase in battery resistance during high-temperature and long-term use is suppressed when these compounds are used is not clear at present, but by using the compound of the present invention, a stable film is formed on the positive electrode and the negative electrode, It is considered that the decomposition of the nonaqueous electrolyte is effectively suppressed.

  The addition amount of the compound of the chemical formula (1) is not particularly limited, but if the addition amount is too small, the effect of addition is small. Conversely, if it is added excessively, not only does the cost of the additive increase, but the effect is also high. Since it tends to be small, the amount of addition to the whole nonaqueous electrolyte when producing the nonaqueous electrolyte is preferably 0.2 wt% to 2.0 wt% with respect to the whole nonaqueous electrolyte, 0.5 wt% to More preferably, it is 1.0 wt%. Here, since the additive is consumed on the electrode when the battery is manufactured and charged and discharged, the amount remaining in the battery is smaller than the amount added to the non-aqueous electrolyte when the battery is manufactured. The amount added here is the amount added to the non-aqueous electrolyte at the time of battery preparation, and the amount remaining in the battery after charge / discharge is smaller than the amount added.

  As the non-aqueous electrolyte, either an electrolytic solution or a solid electrolyte can be used. When an electrolytic solution is used, the electrolytic solution solvent is ethylene carbonate, propylene carbonate, butylene carbonate, trifluoropropylene carbonate, γ-butyrolactone, γ-valerolactone, sulfolane, 1,2-dimethoxyethane, 1,2-diethyl. Ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyl-1,3-dioxolane and dioxolane, fluoroethyl methyl ether, ethylene glycol diacetate, propylene glycol diacetate, ethylene glycol dipropionate, propylene glycol dipropionate, acetic acid Methyl, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, dimethyl carbonate, diethyl carbonate , Ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl isopropyl carbonate, ethyl isopropyl carbonate, diisopropyl carbonate, dibutyl carbonate, acetonitrile, fluoroacetonitrile, ethoxypentafluorocyclotriphosphazene, diethoxytetrafluorocyclo Alkoxy and halogen-substituted cyclic phosphazenes such as triphosphazene and phenoxypentafluorocyclotriphosphazene and chain phosphazenes, phosphate esters such as triethyl phosphate, trimethyl phosphate and trioctyl phosphate, triethyl borate and tributyl borate Boric acid esters such as N-methyloxazolidinone, N-ethyloxa A non-aqueous solvent such as Rijinon, alone or can be used mixed solvents thereof.

The nonaqueous electrolyte is used by dissolving the supporting salt in these nonaqueous solvents. Examples of the supporting salt include LiClO ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ CO ₂ , LiCF ₃ SO ₃ , LiCF ₃ CF ₂ SO ₃ , LiCF ₃ CF ₂ CF ₂ SO ₃ , LiN (SO ₂ CF ₃ ). ₂ , LiN (SO ₂ CF ₂ CF ₃ ) ₂ , LiN (COCF ₃ ) ₂ , LiN (COCF ₂ CF ₃ ) ₂ , LiBF ₂ C ₂ O ₄ , LiBC ₄ O ₈ , LiPF ₂ (C ₂ O ₄ ) ₂ And salts such as LiPF ₃ (CF ₂ CF ₃ ) ₃ or mixtures thereof can be used.

  In order to improve battery characteristics, a small amount of compound may be mixed in the non-aqueous electrolyte, such as vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, propyl vinylene carbonate, phenyl vinylene carbonate, vinyl ethylene carbonate, divinyl ethylene carbonate. , Carbonates such as dimethyl vinylene carbonate, diethyl vinylene carbonate, fluoroethylene carbonate, vinyl esters such as vinyl acetate and vinyl propionate, diallyl sulfide, allyl phenyl sulfide, allyl vinyl sulfide, allyl ethyl sulfide, propyl sulfide, diallyl disulfide, Sulfides such as allylethyl disulfide, allylpropyl disulfide, allylphenyl disulfide, , 3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, cyclic sulfonic acid esters such as 1,4-butene sultone, methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, ethanesulfone Acid methyl, ethyl ethane sulfonate, propyl ethane sulfonate, methyl benzene sulfonate, ethyl benzene sulfonate, propyl benzene sulfonate, phenyl methane sulfonate, phenyl ethane sulfonate, phenyl propane sulfonate, methyl benzyl sulfonate, benzyl sulfone Chain sulfonates such as ethyl acrylate, propyl benzyl sulfonate, benzyl methanesulfonate, benzyl ethanesulfonate, benzyl propanesulfonate, dimethyl sulfite, diethyl sulfite, Tylmethyl sulfite, methyl propyl sulfite, ethyl propyl sulfite, diphenyl sulfite, methyl phenyl sulfite, ethylene sulfite, vinyl ethylene sulfite, divinyl ethylene sulfite, propylene sulfite, vinyl propylene sulfite, butylene sulfite , Sulfites such as vinyl butylene sulfite, vinylene sulfite, phenylethylene sulfite, sulfate esters such as dimethyl sulfate, diethyl sulfate, ethylene glycol sulfate, propylene glycol sulfate, butylene glycol sulfate, pentene glycol sulfate , Benzene, toluene, xylene, fluorobenzene, biphenyl, cyclohexylbenzene, 2-fluoro Aromatic compounds such as phenyl, 4-fluorobiphenyl, diphenyl ether, tert-butylbenzene, orthoterphenyl, metaterphenyl, naphthalene, fluoronaphthalene, cumene, fluorobenzene, 2,4-difluoroanisole, halogens such as perfluorooctane A substituted alkane, tristrimethylsilyl borate, bistrimethylsilyl sulfate, tristrimethylsilyl phosphate, silyl esters such as tetrakistrimethylsilyl titanate, and the like may be added depending on the purpose.

  When a solid electrolyte is used, a porous polymer solid electrolyte membrane may be used as the polymer solid electrolyte, and an electrolyte solution may be further contained in the polymer solid electrolyte. Moreover, when using a gel-like polymer solid electrolyte, the electrolyte solution which comprises gel and the electrolyte solution contained in the pore etc. may differ. When such a polymer solid electrolyte is used, the compound described in the chemical formula (1) of the present invention may be contained in the electrolytic solution. However, when high output is required as in HEV applications, it is more preferable to use a non-aqueous electrolyte alone as the electrolyte than to use a solid electrolyte or a polymer solid electrolyte.

There is no restriction | limiting in particular as a positive electrode active material of the nonaqueous electrolyte secondary battery to which this invention is applied, A various material can be used suitably. For example, transition metal compounds such as manganese dioxide, spinel type lithium manganate, vanadium pentoxide, transition metal chalcogen compounds such as iron sulfide and titanium sulfide, and composite oxides of these transition metals and lithium LixMO _{2− δ} (wherein M represents Co, Ni, or Mn, and 0.4 ≦ x ≦ 1.2 and 0 ≦ δ ≦ 0.5), or these composite oxides include Al, Mn, A compound containing at least one element selected from Fe, Ni, Co, Cr, Ti, Zn, and Zr, or a nonmetallic element such as P and B can be used. Further, preferably a composite oxide of lithium and nickel, that is, a positive electrode active material represented by LixNipM1qM2rO _2-δ (where M1 and M2 are at least selected from Al, Mn, Fe, Co, Cr, Ti, Zn, Zr) It may be a kind of element or a nonmetallic element such as P or B. Furthermore, 0.4 ≦ x ≦ 1.2, 0.8 ≦ p + q + r ≦ 1.2, and 0 ≦ δ ≦ 0.5. Can be used. Examples of the organic compound include conductive polymers such as polyaniline. . Furthermore, the above various active materials may be mixed and used regardless of whether they are inorganic compounds or organic compounds.

Further, as a negative electrode material compound, Al, Si, Pb, Sn, Zn, Cd and lithium alloy, LiFe ₂ O ₃ , WO ₂ , MoO ₂ , SiO, CuO and other metal oxides, non-graphitized Amorphous carbonaceous materials such as carbon and easily graphitizable carbon, crystalline carbon materials such as graphite, lithium nitride such as Li ₃ N, lithium titanate, metallic lithium, or a mixture thereof may be used. A complex may be used. It is particularly preferable to use an amorphous carbon material.

  Moreover, as a separator of the nonaqueous electrolyte battery according to the present invention, a woven fabric, a non-woven fabric, a synthetic resin microporous membrane, or the like can be used, and a synthetic resin microporous membrane can be particularly preferably used. Among them, polyolefin-based microporous membranes such as polyethylene and polypropylene microporous membranes, polyethylene and polypropylene microporous membranes combined with aramid and polyimide, or microporous membranes composited with these have thickness, membrane strength, membrane It is preferably used in terms of resistance and the like.

  Furthermore, a separator can also be used by using a solid electrolyte such as a polymer solid electrolyte. Further, a synthetic resin microporous membrane and a polymer solid electrolyte may be used in combination. In this case, a porous polymer solid electrolyte membrane may be used as the polymer solid electrolyte, and the polymer solid electrolyte may further contain an electrolytic solution. However, in this case, since the battery output is reduced, it is preferable to keep the polymer solid electrolyte in a minimum amount.

  The shape of the battery is not particularly limited, and can be applied to non-aqueous electrolyte secondary batteries having various shapes such as a rectangular shape, a long cylindrical shape, a coin shape, a button shape, a sheet shape, and a cylindrical battery.

  Hereinafter, specific examples to which the present invention is applied will be described. However, the present invention is not limited to the examples, and can be appropriately modified and implemented without departing from the scope of the present invention. .

[Example 1]
FIG. 1 is a schematic cross-sectional view of a prismatic nonaqueous electrolyte secondary battery of the present example. In this rectangular nonaqueous electrolyte secondary battery 1, a positive electrode 3 formed by applying a positive electrode mixture to an aluminum current collector and a negative electrode 4 formed by applying a negative electrode mixture to a copper current collector are interposed via a separator 5. The wound flat flat electrode group 2 and the non-aqueous electrolyte are housed in a battery case 6 and have a width of 34 mm × a height of 50 mm × a thickness of 5.0 mm.

  A battery lid 7 provided with a safety valve 8 is attached to the battery case 6 by laser welding, a negative electrode terminal 9 is connected to the negative electrode 4 via a negative electrode lead 11, and a positive electrode 3 is connected to the battery lid via a positive electrode lead 10. Has been.

The positive electrode plate is composed of 8% by weight of polyvinylidene fluoride as a binder, 6% by weight of acetylene black as a conductive agent, and a positive electrode active material LiCo _0.34 Ni _0.33 Mn which is a lithium-cobalt-nickel-manganese composite oxide. N-methylpyrrolidone is added to a positive electrode mixture obtained by mixing 86% by weight of _0.33 O ₂ to prepare a paste, which is then applied to both sides of a 20 μm thick aluminum foil current collector and dried. It was prepared by.

  A negative electrode plate was prepared by adding 95% by weight of non-graphitizable carbon and 5% by weight of polyvinylidene fluoride to N-methylpyrrolidone to prepare a paste, which was then applied to both sides of a 10 μm thick copper foil current collector and dried. Made by doing.

A polyethylene microporous membrane was used for the separator. In addition, in the electrolytic solution, a mixed solvent of ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) = 3: 2: 5 (volume ratio) was further adjusted to 1 mol / L after adjusting LiPF _6. In addition, bis (vinylsulfonyl) methane [BBSM: CH ₂ CHS (O ₂ ) CH ₂ S (O ₂ ) CHCH ₂ ] is adjusted to a concentration of 0.05 wt% with respect to the entire nonaqueous electrolyte. Each was added to the battery and poured into the battery.

  Three cells of the nonaqueous electrolyte secondary battery of Example 1 were produced by the above-described configuration and procedure.

[Examples 2 to 9]
For the six types of batteries of Examples 2 to 9, as shown in Table 1, the nonaqueous electrolyte secondary battery was exactly the same as Example 1 except that the amount of BBSM added to the nonaqueous electrolyte was changed. Three batteries each were produced.

[Example 10]
For the battery of Example 10, bis (allylsulfonyl) methane [BASM: CH ₂ CHCH ₂ S (O ₂ ) CH ₂ S (O ₂ ) CH ₂ CHCH ₂ ] was used instead of bis (vinylsulfonyl) methane. A nonaqueous electrolyte secondary battery was fabricated in the same manner as in Example 1 except for the above.

[Example 11]
For the battery of Example 11, bis (vinylsulfonyl) propane [BBSP: CH ₂ CHS (O ₂ ) CH ₂ CH ₂ CH ₂ S (O ₂ ) CHCH ₂ ] was used instead of bis (vinylsulfonyl) methane. A nonaqueous electrolyte secondary battery was fabricated in the same manner as in Example 1 except for the above.

[Comparative Example 1]
For the battery of Comparative Example 1, a nonaqueous electrolyte secondary battery was produced in exactly the same manner as in Example 1 except that bis (vinylsulfonyl) methane was not added.

以上のようにして作製した実施例１〜１１および比較例１の角形非水電解質二次電池について、２５℃における初期放電容量を測定し、いずれも４７０ｍＡとほぼ同等の放電容量が得られていることを確認した。なお、放電容量は、２５℃において、充電電流９０ｍＡ、充電電圧４．２８Ｖの定電流−定電圧充電で６時間充電した後、すなわち、９０ｍＡの電流値で充電して電圧が４．２８Ｖに達したのち、定電圧充電をおこない、合計で６時間の充電をおこなった後、放電電流９０ｍＡ、終止電圧２．５０Ｖの条件で定電流放電をおこなうことにより測定した。

With respect to the rectangular nonaqueous electrolyte secondary batteries of Examples 1 to 11 and Comparative Example 1 manufactured as described above, the initial discharge capacity at 25 ° C. was measured, and a discharge capacity almost equal to 470 mA was obtained in each case. It was confirmed. The discharge capacity was 25 ° C. After charging for 6 hours with a constant current-constant voltage charge with a charge current of 90 mA and a charge voltage of 4.28 V, that is, with a current value of 90 mA, the voltage reached 4.28 V. Thereafter, constant voltage charging was performed, charging was performed for a total of 6 hours, and then, constant current discharging was performed under conditions of a discharge current of 90 mA and a final voltage of 2.50 V.

  The DC resistance was measured by setting the battery SOC to 50% by charging for 1 hour at a current value of 0.5 CmA (235 mA) at 25 ° C., and the voltage when discharged at 0.2 CmA for 10 seconds. Measure the voltage when discharged at 0.5 CmA for 10 seconds and the voltage when discharged at 1 CmA for 10 seconds, and measure the slope of the voltage drop (E) with respect to the discharge current (I) (R = E / I) It was measured by.

  The neglect test was conducted by the following method. After measuring the initial DC resistance Ra, the battery was charged at a current value of 0.4 CmA (188 mA) for 2 hours to set the SOC of the battery to 80%, and stored in a constant temperature bath at 60 ° C. for 30 days. After cooling to 25 ° C., the battery was discharged in the same manner as the condition for confirming the initial discharge capacity, and then the DC resistance Rb after the test was measured in the same manner as the condition for measuring the initial DC resistance Ra.

  The increase rate of the DC resistance was calculated from the DC resistance Ra before the 60 ° C. standing test and the DC resistance Rb after the 60 ° C. standing test using the following formula.

DC resistance increase rate (%) = ((Rb / Ra) −1) * 100
Table 2 shows the DC resistance increase rates of Examples 1 to 11 and Comparative Example 1.

比較例１の添加剤未添加の場合は６０℃で３０日放置後の直流抵抗が３７％上昇したのに対し、ＢＢＳＭを０．０５ｗｔ％添加した場合では３５％の増加にとどまった。また、ＢＢＳＭの添加量を５．０ｗｔ％まで増やしていくと、０．０５ｗｔ％から１．０ｗｔ％では添加量が多いほど直流抵抗の増加率は小さくなり、さらに１．０から５．０ｗｔ％と添加量を増やしていくと逆に効果が小さくなる傾向がみられた。いずれの添加量でも比較例１の未添加と比較して直流抵抗の増加率は小さく、直流抵抗増加を低減できることが確認された。しかし、添加量が０．０５ｗｔ％の実施例１や０．１ｗｔ％の実施例２ではその効果が十分大きなものではなく、逆に添加量が３．０ｗｔ％と多過ぎるとＢＢＳＭを添加した効果が小さくなっていくこと、また添加量が０．２ｗｔ％〜２．０ｗｔ％とすることで直流抵抗の増加率が比較例１よりも１５％以上も低かったことから、ＢＢＳＭの添加量としては０．２ｗｔ〜２．０ｗｔ％が好ましいことがわかった。さらに、添加量が０．５ｗｔ％〜１．５ｗｔ％の時に直流抵抗の増加率が比較例１よりも２５％〜２９％低く、直流抵抗の増大抑制効果が著しかったことから、より好ましい添加量は０．５ｗｔ％〜１．５ｗｔ％であることがわかった。ここで、添加量が多い場合に直流抵抗の増加率が実施例５の１．０ｗｔ％添加よりも大きかった理由としては、添加量が過剰であったために、過剰のＢＢＳＭが電池内で好ましくない副反応をおこしたためであると考えられる。

When the additive of Comparative Example 1 was not added, the direct current resistance after standing for 30 days at 60 ° C. increased by 37%, whereas when BBSM was added by 0.05 wt%, the increase was only 35%. Further, when the addition amount of BBSM is increased to 5.0 wt%, the increase rate of DC resistance decreases as the addition amount increases from 0.05 wt% to 1.0 wt%, and further from 1.0 to 5.0 wt%. On the contrary, when the amount added was increased, the effect tended to decrease. In any addition amount, the increase rate of the DC resistance was small compared with the non-addition of Comparative Example 1, and it was confirmed that the increase in DC resistance could be reduced. However, in Example 1 where the addition amount is 0.05 wt% and in Example 2 where the addition amount is 0.05 wt%, the effect is not sufficiently large. Conversely, if the addition amount is too large as 3.0 wt%, the effect of adding BBSM Since the rate of increase in DC resistance was 15% or more lower than that of Comparative Example 1 by adding 0.2 wt% to 2.0 wt%, the amount of BBSM added was It turned out that 0.2 wt-2.0 wt% is preferable. Furthermore, when the addition amount is 0.5 wt% to 1.5 wt%, the rate of increase in DC resistance is 25% to 29% lower than that of Comparative Example 1, and the effect of suppressing the increase in DC resistance was remarkable. Was found to be 0.5 wt% to 1.5 wt%. Here, the reason why the increase rate of the DC resistance was larger than the addition of 1.0 wt% of Example 5 when the addition amount was large was that the addition amount was excessive, and therefore excessive BBSM was not preferable in the battery. This is probably because of a side reaction.

  Further, in Example 10 to which BASM, which is a similar compound of BBSM, was added, the same effect as in Example 4 was obtained. Further, in Example 11 to which BBSP was added, the increase in DC resistance was clearly smaller than that in Comparative Example 1 although it was slightly inferior to Example 4 and Example 10. In addition, although the mixed system of EC: EMC was described here, when the ratio of the cyclic carbonate and the chain carbonate was changed, when the type and concentration of the electrolyte salt were changed, and as the chain carbonate, diethyl The same tendency is observed when using carbonate or methylpropyl carbonate, or when using a carboxylic acid ester such as ethyl acetate, and the same tendency is obtained when propylene carbonate is used as the cyclic carbonate. It was.

The figure which shows the cross-section of the square battery of the Example and comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Square nonaqueous electrolyte secondary battery 2 Winding type electrode group 3 Positive electrode 4 Negative electrode 5 Separator 6 Battery case 7 Battery cover 8 Safety valve 9 Negative electrode terminal 10 Positive electrode lead 11 Negative electrode lead

Claims (3)

A positive electrode having a substance that occludes / releases lithium as a constituent element, a negative electrode having a substance that occludes / releases lithium as a constituent element, and a nonaqueous electrolyte, wherein the nonaqueous electrolyte is represented by chemical formula (1) A non-aqueous electrolyte secondary battery comprising a compound.

(Where n is an integer of 1 to 3, at least one of R1 and R2 is a chain or branched chain group containing a carbon-carbon unsaturated bond, and R3 and R4 are hydrogen atoms, halogens, and substituents. It is one of the group consisting of organic groups that may have a group.) The nonaqueous electrolyte secondary battery according to claim 1, wherein the compound represented by the chemical formula (1) is at least one of bis (vinylsulfonyl) methane and bis (allylsulfonyl) methane. A method for producing a nonaqueous electrolyte secondary battery, which comprises injecting a nonaqueous electrolyte solution containing a compound represented by the chemical formula (1) into a battery to produce a nonaqueous electrolyte secondary battery.

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