JP2003187867A - Nonaqueous electrolyte secondary battery - Google Patents
Nonaqueous electrolyte secondary batteryInfo
- Publication number
- JP2003187867A JP2003187867A JP2001389791A JP2001389791A JP2003187867A JP 2003187867 A JP2003187867 A JP 2003187867A JP 2001389791 A JP2001389791 A JP 2001389791A JP 2001389791 A JP2001389791 A JP 2001389791A JP 2003187867 A JP2003187867 A JP 2003187867A
- Authority
- JP
- Japan
- Prior art keywords
- battery
- secondary battery
- negative electrode
- electrolyte secondary
- solvent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、リチウムイオンを
吸蔵放出できる正極と、リチウムイオンを吸蔵放出でき
る負極とが、溶媒及び電解質から成る電解液が含浸され
たセパレータを介して配置された電極体を有する非水電
解質二次電池に関する。TECHNICAL FIELD The present invention relates to an electrode body in which a positive electrode capable of occluding and releasing lithium ions and a negative electrode capable of occluding and releasing lithium ions are arranged via a separator impregnated with an electrolytic solution containing a solvent and an electrolyte. And a non-aqueous electrolyte secondary battery having
【０００２】[0002]
【従来の技術】近年、携帯用情報端末の発達は目覚し
く、電源として使用される二次電池も大きく需要を伸ば
してきた。特に、リチウムイオン電池に代表される非水
電解質二次電池は、高いエネルギー密度を有し、高容量
化が可能であるということから、広く使用されるように
なってきた。2. Description of the Related Art In recent years, the development of portable information terminals has been remarkable, and the demand for secondary batteries used as a power source has greatly increased. In particular, non-aqueous electrolyte secondary batteries typified by lithium-ion batteries have been widely used because they have high energy density and can have high capacity.
【０００３】ここで、この種の非水系二次電池に用いら
れるセパレータ材料としては、強度が大きく、且つ製造
コストの低減が可能なものであることが要求されるが、
このような要求に答えうるものの一つとして、ポリエチ
レンテレフタレート（以下、ＰＥＴと略す）が提案され
ている。特に、近年では、セパレータの薄膜化を図りつ
つ保液性を向上させるべく、セパレ−タとして不織布を
用いられることが多くなっている。この場合、セパレー
タの薄膜化を実施するにはセパレータの強度を保持しつ
つ繊維自体をより細くする必要があるが、この点におい
て、上記の如く機械的強度の大きなＰＥＴが最適であ
る。一方、電解質としては、ＬｉＢＦ4 、ＬｉＰＦ6 等
多数のものが提案されているが、電導度が高いというこ
とからＬｉＰＦ6が一般的に用いられている。Here, the separator material used in this type of non-aqueous secondary battery is required to have high strength and to be capable of reducing the manufacturing cost.
Polyethylene terephthalate (hereinafter abbreviated as PET) has been proposed as one that can meet such requirements. In particular, in recent years, a non-woven fabric is often used as a separator in order to improve the liquid retaining property while making the separator thin. In this case, in order to reduce the thickness of the separator, it is necessary to make the fiber itself thinner while maintaining the strength of the separator. From this point, PET having a large mechanical strength is optimal. On the other hand, a large number of electrolytes such as LiBF 4 and LiPF 6 have been proposed, but LiPF 6 is generally used because of its high conductivity.
【０００４】しかしながら、セパレータにＰＥＴを用
い、電解質に負極表面上で還元反応を起こしラジカルを
生成する化合物を含む電池では、ＰＥＴが著しく劣化す
る。これは、以下に示す理由によるものと考えられる。
即ち、通常のリチウムイオン二次電池の場合、負極中に
リチウムイオンが挿入されることにより、負極電位は対
金属リチウムで０．１Ｖ程度の値を示す。この際、電解
液中の上記化合物の一部は負極表面で還元反応を起こ
し、ラジカルを形成する。このラジカルが存在する系で
は、ＰＥＴと溶媒との間でエステル交換による分解反応
が進行するため、ＰＥＴが劣化してＰＥＴの分子が切断
されたり、反応副生成物が発生して、電池特性が大きく
低下する。この場合、上記ラジカルは、上記分解反応に
おいて触媒的な役割を担うため、微量のラジカルが発生
しただけで、上記分解反応は連続的に継続する。However, in a battery in which PET is used as the separator and the electrolyte contains a compound that causes a reduction reaction on the surface of the negative electrode to generate radicals, the PET is significantly deteriorated. This is considered to be due to the following reasons.
That is, in the case of an ordinary lithium ion secondary battery, the lithium ion is inserted into the negative electrode, so that the negative electrode potential shows a value of about 0.1 V against lithium metal. At this time, a part of the compound in the electrolytic solution causes a reduction reaction on the surface of the negative electrode to form a radical. In a system in which this radical is present, a decomposition reaction due to transesterification proceeds between PET and a solvent, so that PET is deteriorated and the PET molecule is cleaved, or a reaction by-product is generated to improve the battery characteristics. Greatly reduced. In this case, since the radical plays a catalytic role in the decomposition reaction, only a small amount of the radical is generated and the decomposition reaction continues continuously.
【０００５】また、上記分解反応は高温環境下で加速さ
れるため、高温環境下では活発な分解反応により不純物
が多量に生成され、この不純物の影響により電池特性が
大きく低下する。即ち、上記構成の電池では、高温保存
特性に劣ることになる。Further, since the above decomposition reaction is accelerated in a high temperature environment, a large amount of impurities are generated by the active decomposition reaction in a high temperature environment, and the battery characteristics are greatly deteriorated due to the influence of the impurities. That is, the battery having the above structure is inferior in high temperature storage characteristics.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、以上の事情
に鑑みなされたものであって、 ラジカルがエステル交
換によるＰＥＴの分解反応において触媒的な役割を担う
のを抑制することにより、高温環境下等における上記分
解反応を抑え、これによって、高温環境下等における電
池特性の低下を防止することができる非水電解質二次電
池を提供することを目的としている。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses the radicals from playing a catalytic role in the decomposition reaction of PET by transesterification, thereby suppressing the high temperature environment. An object of the present invention is to provide a non-aqueous electrolyte secondary battery capable of suppressing the above decomposition reaction in the lower part or the like and thereby preventing the deterioration of the battery characteristics in the high temperature environment or the like.
【０００７】[0007]
【課題を解決するための手段】上記目的を達成するため
に、本発明のうちで請求項１記載の発明は、リチウムイ
オンを吸蔵放出できる正極と、リチウムイオンを吸蔵放
出できる負極とが、溶媒及び電解質とから成る電解液が
含浸されたセパレータを介して配置された電極体を有す
る非水電解質二次電池において、上記セパレータとして
ＰＥＴを用い、上記電解質には負極表面上で還元反応を
起こしラジカルを生成する化合物を含み、且つ、上記溶
媒には上記ラジカルによる上記ＰＥＴの分解反応を抑制
する化合物が添加されていることを特徴とする。In order to achieve the above object, the invention according to claim 1 of the present invention is characterized in that a positive electrode capable of occluding and releasing lithium ions and a negative electrode capable of occluding and releasing lithium ions are solvents. And a non-aqueous electrolyte secondary battery having an electrode body disposed via a separator impregnated with an electrolytic solution consisting of an electrolyte, PET is used as the separator, and a radical that causes a reduction reaction on the surface of the negative electrode is used as the electrolyte. And a compound that suppresses the decomposition reaction of PET by the radicals is added to the solvent.
【０００８】前述の如く、通常の非水電解質二次電池の
場合、負極中にリチウムイオンが挿入されると、電解液
中の電解質の一部は負極表面で還元反応を起こし、ラジ
カルを形成する。この場合、上記構成の如く、分解反応
を抑制する化合物が溶媒に添加されていれば、 ラジカ
ルとこの化合物との間で容易に反応が進行するため、ラ
ジカルがＰＥＴの分解反応における触媒的な役割を果た
すのを阻止できる。したがって、ＰＥＴと溶媒との間で
エステル交換による分解反応が生じるのを抑制すること
ができるので、ＰＥＴが劣化してＰＥＴの分子が切断さ
れたり、反応副生成物が発生して、電池特性が大きく低
下するのを抑制することができる。また、高温環境下で
あっても分解反応が抑制されるので、不純物が多量に生
成されるのを防止でき、不純物の影響による電池特性の
劣化を抑えることができる。これらのことから、高温保
存特性が向上する。As described above, in the case of a normal non-aqueous electrolyte secondary battery, when lithium ions are inserted into the negative electrode, a part of the electrolyte in the electrolytic solution causes a reduction reaction on the negative electrode surface to form a radical. . In this case, if a compound that suppresses the decomposition reaction is added to the solvent as in the above-described configuration, the reaction easily proceeds between the radical and this compound, so that the radical plays a catalytic role in the decomposition reaction of PET. Can be fulfilled. Therefore, it is possible to suppress the decomposition reaction due to transesterification between PET and the solvent, so that the PET is deteriorated and the PET molecule is cleaved or a reaction by-product is generated to improve the battery characteristics. It is possible to suppress a large decrease. Further, since the decomposition reaction is suppressed even in a high temperature environment, it is possible to prevent a large amount of impurities from being generated, and it is possible to suppress deterioration of battery characteristics due to the influence of impurities. From these, the high temperature storage characteristics are improved.
【０００９】また、請求項２記載の発明は請求項１記載
の発明において、上記電解質にはＬｉＰＦ6が含まれる
ことを特徴とする。このように負極表面上で還元反応を
起こして、ラジカルを生成する化合物としては、ＬｉＰ
Ｆ6が例示される。The invention according to claim 2 is the invention according to claim 1, characterized in that the electrolyte contains LiPF 6 . As a compound that causes a reduction reaction on the surface of the negative electrode to generate a radical, LiP
F 6 is exemplified.
【００１０】また、請求項３記載の発明は請求項１又は
２の発明において、上記分解反応を抑制する化合物がビ
ニレンカーボネート（以下、ＶＣと略す）であることを
特徴とする。このようにラジカルによるＰＥＴの分解反
応を抑制する化合物としてＶＣが好ましい。The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the compound that suppresses the decomposition reaction is vinylene carbonate (hereinafter abbreviated as VC). VC is preferable as the compound that suppresses the decomposition reaction of PET by radicals.
【００１１】尚、本来ＶＣは負極表面の官能基と反応し
て被膜を形成する働きを有するが、当該被膜は電池に悪
影響を及ぼすことはなく、逆に、当該被膜は負極活物質
と電解液の間の反応を抑制するなど、電池特性に対して
有用な働きを有する。このため、 ラジカルとＶＣとの
反応により生成した副生成物も、電池特性に対して悪影
響を及ぼすことはない。Although VC originally has a function of reacting with a functional group on the surface of the negative electrode to form a film, the film does not adversely affect the battery, and conversely, the film is a negative electrode active material and an electrolytic solution. It has a useful function for the battery characteristics such as suppressing the reaction between the two. Therefore, the by-product generated by the reaction between the radical and VC does not adversely affect the battery characteristics.
【００１２】また、請求項４記載の発明は請求項２又は
３記載の発明において、上記溶媒に対する上記ＬｉＰＦ
6 の割合が、０．０５モル／リットル以上に規制される
ことを特徴とする。このように規制するのは、溶媒に対
するＬｉＰＦ6 の割合が、０．０５モル／リットル未満
であれば、ラジカル生成量が微量であるために、ＰＥＴ
の分解反応の抑制に大きさ効果が得られないからであ
る。Further, the invention according to claim 4 is the same as the invention according to claim 2 or 3, wherein the LiPF is added to the solvent.
The ratio of 6 is regulated to 0.05 mol / liter or more. The reason for regulating in this way is that if the ratio of LiPF 6 to the solvent is less than 0.05 mol / liter, the amount of radicals produced is very small, so that PET
This is because the size effect cannot be obtained in suppressing the decomposition reaction of.
【００１３】また、請求項５記載の発明は請求項３又は
４記載の発明において、上記溶媒の総量に対する上記Ｖ
Ｃの割合が、０．１質量％以上１０質量％以下に規制さ
れることを特徴とする。このように規制するのは、ＶＣ
の割合が０．１質量％未満の場合には、電解液中で発生
するラジカル全てと反応するのに十分な量のＶＣ添加さ
れていないため、 ラジカルの発生を完全には抑制する
ことができず、サイクル特性等の電池特性を飛躍的に向
上させることができない一方、ＶＣの割合が１０質量％
を越えると、 ラジカルによるＰＥＴの劣化は発生しな
いが、ラジカルとの反応や負極表面での被膜形成に消費
されなかったＶＣが電解液特性に影響を与え、電池特性
が劣化するからである。The invention according to claim 5 is the same as the invention according to claim 3 or 4, in which the above V with respect to the total amount of the above solvent is used.
It is characterized in that the proportion of C is regulated to 0.1% by mass or more and 10% by mass or less. It is VC to regulate in this way
When the ratio is less than 0.1% by mass, VC is not added in an amount sufficient to react with all the radicals generated in the electrolytic solution, so that the generation of radicals can be completely suppressed. Therefore, while battery characteristics such as cycle characteristics cannot be dramatically improved, the proportion of VC is 10% by mass.
If it exceeds, the deterioration of PET due to radicals does not occur, but VC not consumed for reaction with radicals and film formation on the surface of the negative electrode affects the electrolytic solution characteristics and deteriorates the battery characteristics.
【００１４】また、請求項６記載の発明は請求項１〜５
記載の発明において、上記ＰＥＴから成るセパレータの
表面には、ポリフッ化ビニリデン（以下ＰＶｄＦと略
す）が付着されていることを特徴とする。上記構成の如
くセパレータ表面にＰＶｄＦが存在する場合には、ＰＶ
ｄＦは電解液を保持してゲル化するため、電解液の移動
やラジカルの運動性が非常に制限されて、分解反応の進
行は最小レベルに抑制される。したがって、高温保存特
性を、一層向上させることができる。The invention according to claim 6 is defined by claims 1 to 5.
In the invention described above, polyvinylidene fluoride (hereinafter abbreviated as PVdF) is attached to the surface of the PET separator. When PVdF is present on the surface of the separator as in the above configuration, PVdF
Since dF retains the electrolytic solution and gels, the movement of the electrolytic solution and the mobility of radicals are extremely limited, and the progress of the decomposition reaction is suppressed to a minimum level. Therefore, the high temperature storage characteristics can be further improved.
【００１５】[0015]
【発明の実施の形態】本発明の実施の形態を、図１〜図
４に基づいて、以下に説明する。図１は本発明に係る非
水電解質二次電池の正面図、図２は図１のＡ−Ａ線矢視
断面図、図３は本発明に係る非水電解質二次電池に用い
るラミネート外装体の断面図、図４は本発明に係る非水
電解質二次電池に用いる電極体の斜視図である。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 is a front view of a non-aqueous electrolyte secondary battery according to the present invention, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a laminated exterior body used for the non-aqueous electrolyte secondary battery according to the present invention. And FIG. 4 is a perspective view of an electrode body used in the non-aqueous electrolyte secondary battery according to the present invention.
【００１６】図２に示すように、本発明の非水電解質二
次電池は電極体１を有しており、この電極体１は収納空
間２内に配置されている。この収納空間２は、図１に示
すように、ラミネート外装体３の上下端と中央部とをそ
れぞれ封止部４ａ・４ｂ・４ｃで封口することにより形
成される。また、上記収納空間内には、エチレンカーボ
ネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）とが
体積比で５０：５０の割合で混合された混合溶媒にＶＣ
が２質量％添加され、更にＬｉＰＦ6 から成るリチウム
塩が１．０モル／リットルの割合で溶解された電解液が
含浸されている。上記電極体１は、ＬｉＣｏＯ2 を主体
とする正極５（厚み：０．１７ｍｍ）と、天然黒鉛（ｄ
値＝３．３６オングストローム）を主体とする負極６
（厚み：０．１４ｍｍ）と、これら両電極を離間するセ
パレータ（図４においては図示せず）とを偏平渦巻き状
に巻回することにより作製される。上記セパレータは、
ポリエチレンテレフタレート（ＰＥＴ）から成る微多孔
膜（厚み：２５μｍ）から構成されている。As shown in FIG. 2, the non-aqueous electrolyte secondary battery of the present invention has an electrode body 1, and the electrode body 1 is arranged in a storage space 2. As shown in FIG. 1, the storage space 2 is formed by sealing the upper and lower ends and the central portion of the laminated outer casing 3 with sealing portions 4a, 4b and 4c, respectively. Further, in the storage space, VC was added to a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 50:50.
2% by mass, and further impregnated with an electrolytic solution in which a lithium salt composed of LiPF 6 is dissolved at a ratio of 1.0 mol / liter. The electrode body 1 includes a positive electrode 5 (thickness: 0.17 mm) mainly composed of LiCoO 2 and natural graphite (d).
Negative electrode 6 whose main value is (3.36 angstrom)
(Thickness: 0.14 mm) and a separator (not shown in FIG. 4) that separates these electrodes from each other are wound in a flat spiral shape. The separator is
It is composed of a microporous film (thickness: 25 μm) made of polyethylene terephthalate (PET).
【００１７】ここで、上記正極５は、アルミニウム箔等
の金属箔から成る正極芯体（厚み：２０μｍ）と、この
正極芯体に活物質が塗布された正極活物質層と、上記正
極芯体に活物質が塗布されていない正極芯体露出部とを
有し、この正極芯体露出部にはアルミニウムから成る正
極集電タブ７が接続されている。また、上記負極６は、
銅箔等の金属箔から成る負極芯体（厚み：２０μｍ）
と、この負極芯体に活物質が塗布された負極活物質層
と、上記負極芯体に活物質が塗布されていない負極芯体
露出部とを有し、この負極芯体露出部には銅から成る負
極集電タブ８が接続されている。そして、上記両集電タ
ブ７・８により、電池内部で生じた化学エネルギーを電
気エネルギーとして外部へ取り出し得るようになってい
る。Here, the positive electrode 5 is a positive electrode core body (thickness: 20 μm) made of metal foil such as aluminum foil, a positive electrode active material layer in which an active material is applied to the positive electrode core body, and the positive electrode core body. To the positive electrode core exposed portion to which the active material is not applied, and the positive electrode current collector tab 7 made of aluminum is connected to the positive electrode core exposed portion. The negative electrode 6 is
Negative electrode core made of metal foil such as copper foil (thickness: 20 μm)
And a negative electrode active material layer in which an active material is applied to the negative electrode core body, and a negative electrode core body exposed portion in which the active material is not applied to the negative electrode core body. And a negative electrode current collecting tab 8 made of Then, both of the current collecting tabs 7 and 8 allow the chemical energy generated inside the battery to be taken out as electric energy.
【００１８】尚、図３に示すように、上記ラミネート外
装体３の具体的な構造は、アルミニウム層１１の一方の
面に、変性ポリプロピレンから成る接着剤層１２を介し
てポリプロピレンから成る樹脂層１３が接着される一
方、アルミニウム層１１の他方の面に、変性ポリプロピ
レンから成る接着剤層１２を介してポリエチレンテレフ
タレートから成る樹脂層１４が接着される構造である。As shown in FIG. 3, the specific structure of the laminated outer package 3 is as follows. A resin layer 13 made of polypropylene is formed on one surface of the aluminum layer 11 via an adhesive layer 12 made of modified polypropylene. While the resin layer 14 made of polyethylene terephthalate is bonded to the other surface of the aluminum layer 11 via the adhesive layer 12 made of modified polypropylene.
【００１９】ここで、上記構造の電池を、以下のように
して作製した。
（正極の作製）先ず、炭酸リチウム（Ｌｉ2 ＣＯ3 ）と
酸化コバルト（Ｃｏ3 Ｏ4 ）とを７００〜９００℃の温
度で焼成して得られたコバルト酸リチウム（ＬｉＣｏＯ
2 ）から成る正極活物質と、導電剤としての黒鉛及びケ
ッチェンブラックと、結着剤としてのフッ素樹脂とを、
質量比で９０：３：２：５の割合で混合し、これをＮ−
メチル−２−ピロリドン（ＮＭＰ）から成る有機溶剤に
溶解してペーストを作製した。次に、このペーストをド
クターブレード法等によりアルミニウム箔（厚み２０μ
ｍ）から成る正極芯体の両面に均一に塗布した。次い
で、加熱された乾燥炉中を通過させ、１００〜１５０℃
の温度で真空熱処理し、ペースト作製時に必要であった
有機溶剤を除去した後、厚さ０．１７ｍｍになるように
ロールプレス機で圧延して正極を作製した。この際、上
記正極集電タブの近傍における上記正極芯体の両面に
は、正極活物質層を形成しない正極芯体露出部を形成し
た。Here, the battery having the above structure was manufactured as follows. (Production of Positive Electrode) First, lithium cobalt oxide (LiCoO 2 ) obtained by firing lithium carbonate (Li 2 CO 3 ) and cobalt oxide (Co 3 O 4 ) at a temperature of 700 to 900 ° C.
2 ) a positive electrode active material, graphite and Ketjen black as a conductive agent, and a fluororesin as a binder,
They were mixed in a mass ratio of 90: 3: 2: 5, and this was mixed with N-
A paste was prepared by dissolving in an organic solvent composed of methyl-2-pyrrolidone (NMP). Next, this paste is applied to an aluminum foil (thickness: 20 μm) by a doctor blade method or the like.
m) was uniformly applied to both surfaces of the positive electrode core. Then, it is passed through a heated drying oven to 100 to 150 ° C.
After vacuum heat treatment at a temperature of 1 to remove the organic solvent necessary for producing the paste, the positive electrode was produced by rolling with a roll press to a thickness of 0.17 mm. At this time, a positive electrode core exposed portion where the positive electrode active material layer was not formed was formed on both surfaces of the positive electrode core near the positive electrode current collector tab.
【００２０】（負極の作製）先ず、天然黒鉛（ｄ値＝
３．３６オングストローム）よりなる負極活物質と、結
着剤としてのフッ素樹脂とを、質量比で９５：５で混合
し、これをＮ−メチル−２−ピロリドンから成る有機溶
剤等に溶解してペーストを作製した。次に、このペース
トをドクターブレード法等により銅箔（厚み：２０μ
ｍ) から成る負極芯体の両面に均一に塗布した。次い
で、加熱された乾燥炉中を通過させ、１００〜１５０℃
の温度で真空熱処理し、ペースト作製時に必要であった
有機溶剤を除去した後、厚さ０．１４ｍｍになるように
ロールプレス機で圧延して負極を作製した。この際、上
記負極集電タブの近傍における上記負極芯体の両面に
は、負極活物質層を形成しない負極芯体露出部を形成し
た。(Production of Negative Electrode) First, natural graphite (d value =
A negative electrode active material composed of 3.36 angstrom) and a fluororesin serving as a binder are mixed at a mass ratio of 95: 5, and the mixture is dissolved in an organic solvent composed of N-methyl-2-pyrrolidone or the like. A paste was made. Next, a copper foil (thickness: 20μ
m) was uniformly applied to both surfaces of the negative electrode core body. Then, it is passed through a heated drying oven to 100 to 150 ° C.
After vacuum heat treatment at a temperature of 1 to remove the organic solvent required at the time of producing the paste, the negative electrode was produced by rolling with a roll press machine to a thickness of 0.14 mm. At this time, negative electrode core exposed portions where the negative electrode active material layer was not formed were formed on both surfaces of the negative electrode core near the negative electrode current collector tab.
【００２１】（電極体の作製）上記正極の正極芯体露出
部に正極集電タブを取り付ける一方、上記負極の負極芯
体露出部に負極集電タブを取り付けた後、これら正負極
間にＰＥＴ製の微多孔膜（厚み：２５μｍ）から成るセ
パレータを配置して重ね合わせた。この後、巻き取り機
を用いて巻回し、最外周をテープ止めして渦巻状の電極
体を作製した後、この渦巻状電極体を扁平に押しつぶし
て扁平渦巻状電極体を作製した。(Preparation of Electrode Body) While the positive electrode current collector tab was attached to the exposed portion of the positive electrode core body of the positive electrode, the negative electrode current collector tab was attached to the exposed portion of the negative electrode core body of the negative electrode, and PET was provided between the positive and negative electrodes. A separator made of a microporous film (thickness: 25 μm) manufactured by the company was placed and superposed. Then, after winding with a winder and tapering the outermost periphery to produce a spiral electrode body, the spiral electrode body was crushed flat to produce a flat spiral electrode body.
【００２２】（電解液の調製）エチレンカーボネート
（ＥＣ）とジエチルカーボネート（ＤＥＣ）とを体積比
が５０：５０となるように混合した混合溶媒に、電解質
塩としてＬｉＰＦ6 を１．０モル／リットルとなるよう
溶解させた。ここに、上記混合溶媒の総量に対する割合
が２質量％となるようにビニレンカーボネート（ＶＣ）
を溶解させて電解液を調製した。(Preparation of Electrolyte Solution) LiPF 6 as an electrolyte salt was added at 1.0 mol / liter in a mixed solvent prepared by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 50:50. It was dissolved so that Here, vinylene carbonate (VC) was added so that the ratio of the mixed solvent to the total amount was 2% by mass.
Was dissolved to prepare an electrolytic solution.
【００２３】（電池の作製）図３に示す５層構造のラミ
ネート材を用意した後、このラミネート材における端部
近傍同士を重ね合わせ、更に、重ね合わせ部を溶着し
て、封止部４ｃを形成した。次に、この筒状のラミネー
ト材の収納空間２内に扁平渦巻状の電極体１を挿入し
た。この際、筒状のラミネート材の一方の開口部から両
集電タブ７・８が突出するように電極体１を配置した。
次に、この状態で、両集電タブ７・８が突出している開
口部のラミネート材を溶着して封止し、封止部４ａを形
成した。この際、溶着は高周波誘導溶着装置を用いて行
った。(Preparation of Battery) After preparing a laminated material having a five-layer structure shown in FIG. 3, the end portions of the laminated material are overlapped with each other, and the overlapped portion is welded to form the sealing portion 4c. Formed. Next, the flat spiral-shaped electrode body 1 was inserted into the accommodating space 2 for the cylindrical laminated material. At this time, the electrode body 1 was arranged such that both current collecting tabs 7 and 8 were projected from one opening of the tubular laminate material.
Next, in this state, the laminate material of the opening from which both the current collecting tabs 7 and 8 project was welded and sealed to form the sealing portion 4a. At this time, the welding was performed using a high frequency induction welding apparatus.
【００２４】次いで、この状態で、真空加熱乾燥（温
度：１０５℃）を２時間行い、ラミネート材及び電極体
１の水分を除去した。この後、上記のようにして調製し
た電解液を収納空間２内に５ｍｌ注液した後、上記封止
部４ａとは反対側のラミネート材の端部を超音波溶着装
置を用いて溶着し、封止部４ｂを形成することにより、
非水電解質二次電池を作製した。このようにして作製し
た電池の容量は５００ｍＡｈであった。尚、正極材料と
しては上記コバルト酸リチウムに限定するものではな
く、リチウムマンガン酸化物、リチウムニッケル酸化
物、リチウム鉄酸化物、又は酸化マンガン等或いはこれ
らの複合体が好適に用いられ、また負極材料としては上
記黒鉛の他、カーボンブラック、コークス、ガラス状炭
素、炭素繊維或いはこれらの焼成体等が好適に用いられ
る。Then, in this state, vacuum heating and drying (temperature: 105 ° C.) were carried out for 2 hours to remove the water content of the laminate material and the electrode body 1. After that, 5 ml of the electrolytic solution prepared as described above was poured into the storage space 2, and then the end of the laminate material on the side opposite to the sealing portion 4a was welded using an ultrasonic welding device, By forming the sealing portion 4b,
A non-aqueous electrolyte secondary battery was produced. The capacity of the battery thus manufactured was 500 mAh. The positive electrode material is not limited to the above lithium cobalt oxide, and lithium manganese oxide, lithium nickel oxide, lithium iron oxide, manganese oxide, or the like or a composite thereof is preferably used, and the negative electrode material is also used. In addition to the above graphite, carbon black, coke, glassy carbon, carbon fiber, or a fired body thereof is preferably used.
【００２５】また、用いられる溶媒としては上記のもの
に限らず、プロピレンカーボネネート、γ−ブチロラク
トンなどの比較的比誘電率が高い溶液と、ジメチルカー
ボネート、メチルエチルカーボネート、テトラヒドロフ
ラン、１，２−ジメトキシエタン、１，３−ジオキソラ
ン、２−メトキシテトラヒドロフラン、ジエチルエーテ
ル等の低粘度低沸点溶媒とを適度な比率で混合した溶媒
を用いることができる。但し、ガス発生抑制の点から、
酸化電位が、４．８Ｖ（ｖｓ Ｌｉ／Ｌｉ+ ）以上のも
のを用いるのが望ましい。更に、外装体としては、アル
ミラミネート外装体に限定されるものではなく、鉄、ア
ルミニウム等の金属から成る外装体を有するものであっ
ても、本発明を適用しうることは勿論である。The solvent used is not limited to the above-mentioned ones, but a solution having a relatively high relative dielectric constant such as propylene carbonate or γ-butyrolactone, dimethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, 1,2- A solvent obtained by mixing a low-viscosity low-boiling point solvent such as dimethoxyethane, 1,3-dioxolane, 2-methoxytetrahydrofuran, or diethyl ether in an appropriate ratio can be used. However, from the viewpoint of suppressing gas generation,
It is desirable to use one having an oxidation potential of 4.8 V (vs Li / Li + ) or more. Further, the exterior body is not limited to the aluminum laminate exterior body, and it goes without saying that the present invention can be applied even if the exterior body is made of a metal such as iron or aluminum.
【００２６】[0026]
【実施例】（第１実施例）
〔実施例〕実施例としては、上記発明の実施の形態で示
した電池を用いた。このようにして作製した電池を、以
下、本発明電池Ａと称する。
〔比較例〕電解液にＶＣを添加しない他は、上記実施例
と同様にして電池を作製した。このようにして作製した
電池を、以下、比較電池Ｘと称する。EXAMPLES (First Example) [Example] As an example, the battery shown in the embodiment of the present invention was used. The battery thus manufactured is hereinafter referred to as Battery A of the invention. [Comparative Example] A battery was produced in the same manner as in the above-described example except that VC was not added to the electrolytic solution. The battery thus manufactured is hereinafter referred to as comparative battery X.
【００２７】〔実験〕上記本発明電池Ａと比較電池Ｘと
を、下記の実験条件で満充電状態とし高温で保存したと
きの、電池電圧の変化と電池厚みの変化とを調べたの
で、その結果を表１に示す。
・実験条件
各電池を５００ｍＡ（１．０Ｉｔ）の充電電流で４．２
Ｖになるまで定電流充電し、その後４．２Ｖの定電圧で
２時間充電して満充電状態とした。次に、各電池の電圧
と厚みとを測定した後、８０℃の恒温槽中で４日間保存
し、保存前後での電池電圧の変化及び電池厚みの変化を
観測した。[Experiment] The battery A of the present invention and the comparative battery X were examined for the change in battery voltage and the change in battery thickness when the battery was fully charged under the following experimental conditions and stored at high temperature. The results are shown in Table 1. -Experimental conditions 4.2 with a charging current of 500 mA (1.0 It) for each battery.
The battery was charged with a constant current until it reached V, and then charged with a constant voltage of 4.2 V for 2 hours to be in a fully charged state. Next, after measuring the voltage and thickness of each battery, the battery was stored in an 80 ° C. constant temperature bath for 4 days, and changes in the battery voltage and changes in the battery thickness before and after storage were observed.
【００２８】[0028]
【表１】 [Table 1]
【００２９】表１から明らかなように、ＶＣを添加して
いない比較電池Ｘでは、高温保存により電池電圧が大き
く低下し、しかも、電池厚みが増大していた。これに対
して、ＶＣを添加した電解液を用いた本発明電池Ａで
は、電池電圧の低下が抑制され、しかも、電池厚みの増
大も抑制されていた。そこで、高温保存試験終了後に両
電池を解体したところ、ＶＣを添加した本発明電池Ａで
は内部に大きな変化は観測されなかったのに対して、Ｖ
Ｃを添加していない比較電池Ｘでは通常白色のセパレー
タが濃赤色に変色している様子が観測された。そして、
変色したセパレータの強度を測定したところ、大きく低
下していることも確認された。As is clear from Table 1, in the comparative battery X to which VC was not added, the battery voltage was greatly lowered and the battery thickness was increased due to high temperature storage. On the other hand, in the battery A of the present invention using the electrolytic solution containing VC, the decrease in battery voltage was suppressed and the increase in battery thickness was also suppressed. Therefore, when both batteries were disassembled after the high temperature storage test was completed, no large internal change was observed in the battery A of the present invention to which VC was added.
In the comparative battery X to which C was not added, it was observed that the normally white separator turned dark red. And
When the strength of the discolored separator was measured, it was also confirmed that it was greatly reduced.
【００３０】ここで、通常のリチウムイオン二次電池の
場合、負極中にリチウムイオンが挿入されることによ
り、負極電位は対金属リチウムで０．１Ｖ程度の値を示
す。この際、電解液中のＬｉＰＦ6 の一部は負極表面で
還元反応を起こし、ＰＦ5 - ラジカルを形成する。この
ＰＦ5 - ラジカルが存在する系では、ＰＥＴと溶媒の間
でエステル交換による分解反応が進行するため、ＰＥＴ
が劣化して、ＰＥＴの分子が切断されたり、反応副生成
物が発生して、電池特性が大きく低下する。この場合、
上記ＰＦ5 - ラジカルは上記分解反応において触媒的な
役割を担うため、微量のＰＦ5 - ラジカルが発生しただ
けで、分解反応は連続的に継続する。また、上記分解反
応は高温環境下で加速されるため、高温環境下では分解
反応により不純物が多量に生成され、この不純物の影響
により電池特性が著しく劣化する。この結果、比較電池
Ｘでは電池電圧の大幅な低下を生じたものと考えられ
る。Here, in the case of a normal lithium ion secondary battery, the lithium ion is inserted into the negative electrode, so that the negative electrode potential shows a value of about 0.1 V against lithium metal. At this time, part of LiPF 6 in the electrolytic solution causes a reduction reaction at the negative electrode surface, PF 5 - to form a radical. The PF 5 - In a system where the radical is present, the decomposition reaction by transesterification between PET and the solvent proceeds, PET
Deteriorates, the molecules of PET are cleaved, reaction by-products are generated, and the battery characteristics are greatly deteriorated. in this case,
Since the PF 5 − radical plays a catalytic role in the decomposition reaction, the decomposition reaction continues continuously even if only a small amount of PF 5 − radical is generated. Further, since the decomposition reaction is accelerated in a high temperature environment, a large amount of impurities are generated by the decomposition reaction in a high temperature environment, and the battery characteristics are significantly deteriorated due to the influence of the impurities. As a result, it is considered that in Comparative Battery X, the battery voltage dropped significantly.
【００３１】これに対して、ＶＣを添加した本発明電池
Ａでは、ＰＦ5 - ラジカルとＶＣとの間で容易に反応が
進行するため、ＰＦ5 - ラジカルが分解反応における触
媒的な役割を果たすのを阻止できる。したがって、ＰＥ
Ｔと溶媒との間でエステル交換による分解反応が抑制さ
れるので、ＰＥＴが劣化してＰＥＴの分子が切断された
り、反応副生成物が発生して、電池特性が大きく低下す
るのを抑制することができる。また、高温環境下であっ
ても分解反応が抑制されるので、不純物が多量に生成さ
れるのを防止でき、不純物の影響による電池特性の劣化
を抑えることができる。この結果、上記の如く、本発明
電池Ａでは高温保存特性が向上するものと考えられる。[0031] In contrast, in the present invention battery A was added VC, PF 5 - for easy reaction between the radicals and the VC proceeds, PF 5 - play a catalytic role in the radical decomposition reaction Can be prevented. Therefore, PE
Since the decomposition reaction due to transesterification between T and the solvent is suppressed, it is possible to prevent the deterioration of the PET, the molecules of the PET being cleaved, and the reaction by-products to be generated, thereby significantly reducing the battery characteristics. be able to. Further, since the decomposition reaction is suppressed even in a high temperature environment, it is possible to prevent a large amount of impurities from being generated, and it is possible to suppress deterioration of battery characteristics due to the influence of impurities. As a result, as described above, it is considered that the battery A of the present invention has improved high temperature storage characteristics.
【００３２】尚、本来ＶＣは負極表面の官能基と反応し
て被膜を形成する働きを有するが、当該被膜は電池に悪
影響を及ぼすことはなく、逆に、当該被膜は負極活物質
と電解液の間の反応を抑制するなど、電池特性に対して
有用な働きを有する。このため、ラジカルとＶＣとの反
応により生成した副生成物も、電池特性に対して害を及
ぼすことはない。また、ここでは詳細には示さないが、
セパレータとしてＰＥＴから成る微多孔膜の代わりに、
ＰＥＴから成る不織布を用いた場合にも、上記と同様の
傾向であることを実験により確認している。Although VC originally has a function of reacting with a functional group on the surface of the negative electrode to form a film, the film does not adversely affect the battery, and conversely, the film is a negative electrode active material and an electrolytic solution. It has a useful function for the battery characteristics such as suppressing the reaction between the two. Therefore, the by-product generated by the reaction between radicals and VC does not harm the battery characteristics. Also, although not shown in detail here,
Instead of a microporous membrane made of PET as a separator,
It has been confirmed by experiments that the same tendency as described above is obtained when a non-woven fabric made of PET is used.
【００３３】（第２実施例）
〔実施例１〜４〕電解質として、それぞれ、０．０２モ
ル／リットル（以下、Ｍと略す）のＬｉＰＦ6 と０．９
８ＭのＬｉＢＦ4 との混合物、０．０５ＭのＬｉＰＦ6
と０．９５ＭのＬｉＢＦ4 との混合物、０．１ＭのＬｉ
ＰＦ6 と０．９ＭのＬｉＢＦ4 との混合物、及び、０．
５ＭのＬｉＰＦ6 と０．５ＭのＬｉＢＦ4 との混合物を
用いた他は、上記第１実施例の実施例と同様にして電池
を作製した。このようにして作製した電池を、以下、そ
れぞれ本発明電池Ｂ１〜Ｂ４と称する。Second Example [Examples 1 to 4] As electrolytes, 0.02 mol / liter (hereinafter abbreviated as M) of LiPF 6 and 0.9, respectively.
Mixture with 8M LiBF 4 , 0.05M LiPF 6
And 0.95M LiBF 4 mixture, 0.1M Li
A mixture of PF 6 and 0.9 M LiBF 4 , and 0.
A battery was made in the same manner as in the example of the first example except that a mixture of 5M LiPF 6 and 0.5M LiBF 4 was used. The batteries thus manufactured are hereinafter referred to as present batteries B1 to B4, respectively.
【００３４】〔比較例１〕電解質として、１．０ＭのＬ
ｉＢＦ4 を用いた他は、上記実施例１と同様にして電池
を作製した。このようにして作製した電池を、以下、比
較電池Ｙ１と称する。
〔比較例２〜６〕ＶＣを添加しない他は、それぞれ、上
記実施例１〜４及び比較例Ｙ１と同様にして電池を作製
した。このようにして作製した電池を、以下、それぞれ
比較電池Ｙ２〜Ｙ６と称する。Comparative Example 1 1.0 M L was used as the electrolyte.
A battery was produced in the same manner as in Example 1 except that iBF 4 was used. The battery thus manufactured is hereinafter referred to as comparative battery Y1. [Comparative Examples 2 to 6] Batteries were produced in the same manner as in Examples 1 to 4 and Comparative Example Y1 except that VC was not added. The batteries thus manufactured are hereinafter referred to as comparative batteries Y2 to Y6, respectively.
【００３５】〔実験〕上記本発明電池Ａ及びＢ１〜Ｂ４
と、比較電池Ｘ及びＹ１〜Ｙ６とを、下記の実験条件で
満充電状態とし高温で保存したときの、電池電圧の変化
を調べたので、その結果を表２に示す。
・実験条件
各電池を５００ｍＡ（１．０Ｉｔ）の充電電流で４．２
Ｖになるまで定電流充電し、その後４．２Ｖの定電圧で
２時間充電して満充電状態とした。次に、各電池の電圧
を測定した後、８０℃の恒温槽中で４日間保存し、保存
前後での電池電圧の変化を観測した。[Experiment] Batteries A and B1 to B4 of the present invention
And the comparative batteries X and Y1 to Y6 were examined for changes in battery voltage when the batteries were fully charged under the following experimental conditions and stored at high temperature. The results are shown in Table 2. -Experimental conditions 4.2 with a charging current of 500 mA (1.0 It) for each battery.
The battery was charged with a constant current until it reached V, and then charged with a constant voltage of 4.2 V for 2 hours to be in a fully charged state. Next, after measuring the voltage of each battery, the battery was stored in an 80 ° C. constant temperature bath for 4 days, and changes in the battery voltage before and after storage were observed.
【００３６】[0036]
【表２】 [Table 2]
【００３７】表２から明らかなように、電解液中のＬｉ
ＰＦ6 濃度が０の場合には、ＶＣの添加の有無に係わら
ず殆ど差異は認められず（比較電池Ｙ１と比較電池Ｙ６
との対比）、また電解液中のＬｉＰＦ6 濃度が０．０５
Ｍ未満の場合には、ＶＣを添加すると、若干電池電圧の
降下が小さくなっていることが認められる（本発明電池
Ｂ１と比較電池Ｙ２との対比）。一方、電解液中にＬｉ
ＰＦ6 が０．０５Ｍ以上の存在する場合には、ＶＣを添
加していない電池（比較電池Ｘ、比較電池Ｙ３〜Ｙ５）
では大きな電池電圧の降下が発生していたのに対して、
電解液中にＶＣを添加した電池（本発明電池Ａ、本発明
電池Ｂ２〜Ｂ４）では、電池電圧の降下は大きく抑制さ
れていることが認められる。As is clear from Table 2, Li in the electrolytic solution
When the PF 6 concentration is 0, almost no difference is observed regardless of whether or not VC is added (comparative battery Y1 and comparative battery Y6).
In contrast, the LiPF 6 concentration in the electrolyte is 0.05
When it is less than M, it is observed that the addition of VC causes a slight decrease in the battery voltage (comparison between the present battery B1 and the comparative battery Y2). On the other hand, Li in the electrolytic solution
When PF 6 is present in an amount of 0.05 M or more, batteries containing no VC (Comparative battery X, Comparative batteries Y3 to Y5)
Then, while a large drop in battery voltage occurred,
It is recognized that in the batteries in which VC is added to the electrolytic solution (the present invention battery A, the present invention batteries B2 to B4), the battery voltage drop is greatly suppressed.
【００３８】これは、負極上でのＰＦ5 - ラジカル形成
はＬｉＰＦ6 に特有の反応であり、他の電解質（例え
ば、上記ＬｉＢＦ4 ）では発生しない。また、詳細には
判明していないが、ごく少量添加されたＬｉＰＦ6 は電
池作製初期において正極表面での固体電解質膜形成など
により消費されるために、ＰＥＴの劣化を発生させるＰ
Ｆ5 - ラジカルを生じないものと推測される。したがっ
て、電解液中のＬｉＰＦ 6 - 濃度が０の場合や、０．０
５Ｍ未満の場合には、ＶＣの添加による高温保存特性の
向上は余り認められないと考えられる。これに対して、
電解液中にＬｉＰＦ6 が０．０５Ｍ以上の存在する場合
にはＰＦ5 - ラジカルが発生するため、ＶＣが添加され
ていない電池では、ＰＥＴ分子が切断し、それに起因し
た電池特性の低下が生じるものと考えられる。This is the PF on the negative electrode.Five - Radical formation
Is LiPF6 It is a reaction peculiar to
For example, the above LiBFFour) Does not occur. Also, in detail
Not known, but a very small amount of LiPF6 Is electric
Formation of solid electrolyte membrane on the surface of positive electrode in the early stage of pond preparation
Is consumed by P, which causes deterioration of PET.
FFive - It is presumed that it does not generate radicals. According to
And LiPF in the electrolyte 6 -When the concentration is 0 or 0.0
If it is less than 5M, the addition of VC may result in high temperature storage characteristics.
It seems that the improvement is not so much recognized. On the contrary,
LiPF in the electrolyte6Is above 0.05M
PFFive - Since radicals are generated, VC is added
Not in the battery, the PET molecules are cleaved and
It is considered that the battery characteristics deteriorate.
【００３９】（第３実施例）
（実施例１〜８）溶媒の総量に対するＶＣの割合を、そ
れぞれ、０．０５質量％、０．１質量％、０．５質量
％、１．０質量％、３．０質量％、５．０質量％、１０
質量％、及び２０質量％とする他は、上記第１実施例の
実施例と同様にして電池を作製した。このようにして作
製した電池を、以下、それぞれ本発明電池Ｃ１〜Ｃ８と
称する。(Third Example) (Examples 1 to 8) The proportions of VC with respect to the total amount of the solvent are 0.05% by mass, 0.1% by mass, 0.5% by mass and 1.0% by mass, respectively. , 3.0% by mass, 5.0% by mass, 10
A battery was made in the same manner as in the above-described first example except that the amounts were set to 20% by mass and 20% by mass. The batteries thus manufactured are hereinafter referred to as the present batteries C1 to C8, respectively.
【００４０】（実験）上記本発明電池Ｃ１〜Ｃ８、及び
前記第１実施例で示した本発明電池Ａ及び比較電池Ｘを
下記の条件で充放電し、各電池のサイクル特性を調べた
ので、その結果を表３に示す。
・充放電条件
５００ｍＡ（１．０Ｉｔ）の充電電流で４．２Ｖになる
まで定電流充電し、その後４．２Ｖの定電圧で２時間充
電して満充電状態とし、５分間放置後、５００ｍＡ
（１．０Ｉｔ）の放電電流で２．７５Ｖになるまで放電
するという条件。尚、放電容量維持率とは、１サイクル
目の放電容量に対する５００サイクル終了後放電容量の
比率である。(Experiment) The batteries C1 to C8 of the present invention, and the battery A of the present invention and the comparative battery X shown in the first embodiment were charged and discharged under the following conditions, and the cycle characteristics of each battery were examined. The results are shown in Table 3. -Charging / discharging condition: Constant current charging was performed at a charging current of 500 mA (1.0 It) until the voltage reached 4.2 V, and then charged at a constant voltage of 4.2 V for 2 hours to reach a fully charged state and left for 5 minutes, then 500 mA.
A condition of discharging to 2.75 V with a discharge current of (1.0 It). The discharge capacity retention rate is the ratio of the discharge capacity after the end of 500 cycles to the discharge capacity of the first cycle.
【００４１】[0041]
【表３】 [Table 3]
【００４２】上記表３から明らかなように、電解液中に
ＶＣが添加されていない比較電池Ｘでは、充放電サイク
ルを繰り返すと放電容量が大きく低下していることが認
められたのに対して、電解液中にＶＣが添加された本発
明電池Ａ及び本発明電池Ｃ１〜Ｃ８では、充放電サイク
ルを繰り返しても放電容量の低下が抑制されていること
が認められた。特に、０．１質量％以上１０質量％以下
のＶＣを添加した本発明電池Ａ及び本発明電池Ｃ２〜Ｃ
７では、充放電サイクルを繰り返しても放電容量の低下
が極めて抑制されていることが認められた。As is apparent from Table 3 above, in Comparative Battery X in which VC was not added to the electrolytic solution, it was found that the discharge capacity was significantly reduced when the charge / discharge cycle was repeated. It was confirmed that in the battery A of the present invention and the batteries C1 to C8 of the present invention in which VC was added to the electrolytic solution, the decrease in discharge capacity was suppressed even after repeating the charge / discharge cycle. In particular, the battery A of the present invention and the batteries C2 to C of the present invention to which 0.1% by mass or more and 10% by mass or less of VC are added.
In No. 7, it was confirmed that the decrease in discharge capacity was extremely suppressed even when the charge / discharge cycle was repeated.
【００４３】上記結果となったのは、以下に示す理由に
よるものと考えられる。即ち、ＶＣは負極活物質表面に
皮膜を形成し、電解液と負極活物質との間の反応を抑制
することから、一般にＶＣを添加するとサイクル特性は
向上する。しかし、上記実験におけるＶＣの添加の有無
による差は、従来のＶＣを添加したことによるサイクル
特性の改善に比べ著しく大きくなることがわかった。こ
れは、ＶＣを添加することにより、 ＰＦ5 - ラジカル
によるＰＥＴの分解反応の発生が抑制されたためである
ものと考えられる。但し、ＶＣの添加量が少ない場合
（ＶＣの添加量が０．０５質量％の本発明電池Ｃ１の場
合）、電解液中で発生するＰＦ5 - ラジカル全てと反応
するのに十分な量のＶＣ添加されていないため、 ＰＦ5
- ラジカルの発生を完全には抑制することができず、
サイクル特性を飛躍的に向上させることができない。一
方、ＶＣの割合が１０質量％を越えた場合（ＶＣの添加
量が２０質量％の本発明電池Ｃ８の場合）、 ＰＦ5 -
ラジカルによるＰＥＴの劣化は発生しないが、ＰＦ5 -
ラジカルとの反応や負極表面での被膜形成に消費されな
かったＶＣが電解液特性に影響を与え、サイクル特性の
劣化が発生しているものと推測される。The above results are considered to be due to the following reasons. That is, since VC forms a film on the surface of the negative electrode active material and suppresses the reaction between the electrolytic solution and the negative electrode active material, the addition of VC generally improves the cycle characteristics. However, it was found that the difference between the presence and absence of the addition of VC in the above experiment was significantly larger than the improvement of the cycle characteristics due to the addition of the conventional VC. This is because the addition of VC, PF 5 - occurrence of decomposition reaction of PET by radicals believed because that is inhibited. However, (when the additive amount of VC is 0.05% by weight of the present battery C1) When the amount of VC is low, generated in the electrolytic solution PF 5 - in an amount sufficient to react with all radicals VC Since it is not added, PF 5
- it can not be suppressed completely the generation of radicals,
Cycle characteristics cannot be dramatically improved. On the other hand, (When the amount of VC is 20 weight% of the present battery C8) If the percentage of VC exceeds 10 wt%, PF 5 -
Although deterioration of PET does not occur by a radical, PF 5 -
It is presumed that VC that was not consumed in the reaction with the radicals and the film formation on the surface of the negative electrode affected the electrolytic solution characteristics, and the cycle characteristics were deteriorated.
【００４４】（第４実施例）
〔実施例〕セパレータとして、ＰＥＴ製の微多孔膜の表
面にＰＶｄＦ層（厚み：１０μｍ）を形成したものを用
いた他は、上記第１実施例の実施例と同様にして電池を
作製した。このようにして作製した電池を、以下、本発
明電池Ｄと称する。(Fourth Embodiment) [Embodiment] The embodiment of the above-mentioned first embodiment except that a PVdF layer (thickness: 10 μm) formed on the surface of a PET microporous film is used as the separator. A battery was prepared in the same manner as in. The battery thus manufactured is hereinafter referred to as Battery D of the invention.
【００４５】〔実験〕上記本発明電池Ｄ及び上記第１実
施例の実施例に示した本発明電池Ａとを、下記の実験条
件で満充電状態とし高温で保存したときの、残存容量比
を調べたので、その結果を表４に示す。
・実験条件
各電池を５００ｍＡ（１．０Ｉｔ）の充電電流で４．２
Ｖになるまで定電流充電し、その後４．２Ｖの定電圧で
２時間充電して満充電状態とした。次に、各電池の電池
容量を測定し、再度上記と同様の条件で満充電状態とし
た後、８０℃の恒温槽中で４日間保存し、保存後の電池
容量を測定した。尚、残存容量比は、保存前の電池容量
に対する保存後の電池容量の比率を算出することにより
求めた。[Experiment] The remaining capacity ratio when the battery D of the present invention and the battery A of the present invention shown in the examples of the first embodiment were stored at high temperature in a fully charged state under the following experimental conditions. The results are shown in Table 4. -Experimental conditions 4.2 with a charging current of 500 mA (1.0 It) for each battery.
The battery was charged with a constant current until it reached V, and then charged with a constant voltage of 4.2 V for 2 hours to be in a fully charged state. Next, the battery capacity of each battery was measured, and after fully charged again under the same conditions as above, the battery was stored in an 80 ° C. thermostat for 4 days, and the battery capacity after storage was measured. The remaining capacity ratio was determined by calculating the ratio of the battery capacity after storage to the battery capacity before storage.
【００４６】[0046]
【表４】 [Table 4]
【００４７】表４から明らかなように、本発明電池Ｄは
本発明電池Ａと比べて高温保存後における残存容量比が
高くなっていることが認められる。これは、以下に示す
理由によるものと考えられる。即ち、ＶＣを添加するこ
とによってＬｉＰＦ6 に起因するＰＦ5 - ラジカルによ
るＰＥＴの分解反応は大きく抑制されるが、特に充電状
態で長時間保存した場合、電解液はより長時間低い電位
にされた状態となるため、僅かずつではあるがＰＦ5 -
ラジカルの発生が進行する。この場合、本発明電池Ａの
如く、セパレータの表面にＰＶｄＦ層が存在しない場合
には、電解液が自由に移動でき、 ＰＦ5 - ラジカルの運
動性が高いため、分解反応がある程度進行する。これに
対して、本発明電池Ｄの如くセパレータ表面にＰＶｄＦ
層が存在する場合には、ＰＶｄＦは電解液を保持してゲ
ル化する。このように、ＰＶｄＦによりゲル化した電解
質中では、電解液の移動やＰＦ5 - ラジカルの運動性が
非常に制限されて、分解反応の進行は最小レベルに抑制
されるという理由によるものと考えられる。As is apparent from Table 4, the battery D of the present invention
Compared to the battery A of the present invention, the residual capacity ratio after high temperature storage is
It is recognized that it has become higher. This is shown below
This is probably due to the reason. That is, VC should be added.
And by LiPF6 PF caused byFive - By radicals
The decomposition reaction of PET is greatly suppressed.
If stored for a long period of time, the electrolyte will have a lower potential for a longer period of time.
However, the PFFive -
Radical generation proceeds. In this case, the battery A of the present invention
If the PVdF layer does not exist on the separator surface,
The electrolyte can move freely in theFive - Radical luck
Due to its high mobility, the decomposition reaction proceeds to some extent. to this
On the other hand, as in Battery D of the present invention, PVdF is formed on the separator surface.
If a layer is present, PVdF will retain the electrolyte and
To convert Thus, PVdF gelled electrolysis
In quality, movement of electrolyte and PFFive - Radical motility
Very limited, the progress of the decomposition reaction is suppressed to the minimum level
It is thought to be due to the fact that it is done.
【００４８】[0048]
【発明の効果】以上説明したように、本発明によれば、
ＰＦ5 - ラジカルがエステル交換による分解反応にお
いて触媒的な役割を担うのを抑制することができるの
で、高温環境下における分解反応を抑え、これによっ
て、高温環境下における電池特性の劣化を防止でき、且
つサイクル特性を向上させることができるといった優れ
た効果を奏する。As described above, according to the present invention,
PF 5 - since radicals can be inhibited from play a catalytic role in the decomposition reaction by transesterification, suppressing a decomposition reaction in a high temperature environment, thereby, possible to prevent the deterioration of the battery characteristics under high temperature conditions, Further, it has an excellent effect that the cycle characteristics can be improved.
【図１】本発明に係る非水電解質二次電池の正面図。FIG. 1 is a front view of a non-aqueous electrolyte secondary battery according to the present invention.
【図２】図１のＡ−Ａ線矢視断面図。FIG. 2 is a sectional view taken along the line AA of FIG.
【図３】本発明に係る非水電解質二次電池に用いるアル
ミラミネート外装体の断面図。FIG. 3 is a cross-sectional view of an aluminum laminate exterior body used for the non-aqueous electrolyte secondary battery according to the present invention.
【図４】本発明に係る非水電解質二次電池に用いる発電
要素の斜視図。FIG. 4 is a perspective view of a power generation element used in the non-aqueous electrolyte secondary battery according to the present invention.
１：発電要素 ２：収納空間 ３：アルミラミネート外装体 ５：正極 ６：負極 1: Power generation element 2: Storage space 3: Aluminum laminated exterior body 5: Positive electrode 6: Negative electrode
フロントページの続き (72)発明者 生川 訓 大阪府守口市京阪本通２丁目５番５号 三 洋電機株式会社内 Ｆターム(参考） 5H021 CC04 EE08 EE10 EE23 HH01 HH07 5H029 AJ01 AJ05 AK03 AL07 AM02 AM03 AM04 AM05 AM07 BJ02 BJ14 DJ04 DJ09 EJ04 EJ12 HJ01 HJ10 Continued front page (72) Inventor, Kun Ikukawa 2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture Within Yo Denki Co., Ltd. F-term (reference) 5H021 CC04 EE08 EE10 EE23 HH01 HH07 5H029 AJ01 AJ05 AK03 AL07 AM02 AM03 AM04 AM05 AM07 BJ02 BJ14 DJ04 DJ09 EJ04 EJ12 HJ01 HJ10
Claims (6)
と、リチウムイオンを吸蔵放出できる負極とが、溶媒及
び電解質から成る電解液が含浸されたセパレータを介し
て配置された電極体を有する非水電解質二次電池におい
て、 上記セパレータとしてポリエチレンテレフタレートを用
い、上記電解質には負極表面上で還元反応を起こしラジ
カルを生成する化合物を含み、且つ、上記溶媒には上記
ラジカルによる上記ポリエチレンテレフタレートの分解
反応を抑制する化合物が添加されていることを特徴とす
る非水電解質二次電池。1. A non-aqueous electrolyte having an electrode body in which a positive electrode capable of occluding and releasing lithium ions and a negative electrode capable of occluding and releasing lithium ions are arranged with a separator impregnated with an electrolytic solution composed of a solvent and an electrolyte. In the secondary battery, polyethylene terephthalate is used as the separator, the electrolyte contains a compound that causes a reduction reaction on the surface of the negative electrode to generate a radical, and the solvent suppresses the decomposition reaction of the polyethylene terephthalate by the radical. A non-aqueous electrolyte secondary battery containing a compound.
とを特徴とする請求項１記載の非水電解質二次電池。2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the electrolyte contains LiPF 6 .
ンカーボネートであることを特徴とする請求項１又は２
記載の非水電解質二次電池。3. The compound according to claim 1, wherein the compound suppressing the decomposition reaction is vinylene carbonate.
The non-aqueous electrolyte secondary battery described.
が、０．０５モル／リットル以上に規制されることを特
徴とする請求項２又は３記載の非水電解質二次電池。4. The non-aqueous electrolyte secondary battery according to claim 2, wherein the ratio of the LiPF 6 to the solvent is regulated to 0.05 mol / liter or more.
ーボネートの割合が、０．１質量％以上１０質量％以下
に規制されることを特徴とする請求項３又は４記載の非
水電解質二次電池。5. The non-aqueous electrolyte secondary battery according to claim 3, wherein the ratio of the vinylene carbonate to the total amount of the solvent is regulated to 0.1% by mass or more and 10% by mass or less.
セパレータの表面には、ポリフッ化ビニリデンが付着さ
れている、請求項１〜５記載の非水電解質二次電池。6. The non-aqueous electrolyte secondary battery according to claim 1, wherein polyvinylidene fluoride is attached to the surface of the separator made of polyethylene terephthalate.
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|---|---|---|---|
| JP2001389791A JP2003187867A (en) | 2001-12-21 | 2001-12-21 | Nonaqueous electrolyte secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001389791A JP2003187867A (en) | 2001-12-21 | 2001-12-21 | Nonaqueous electrolyte secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2003187867A true JP2003187867A (en) | 2003-07-04 |
Family
ID=27597906
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|---|---|---|---|
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| Country | Link |
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| JP2008047398A (en) * | 2006-08-14 | 2008-02-28 | Sony Corp | Nonaqueous electrolyte secondary battery |
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2001
- 2001-12-21 JP JP2001389791A patent/JP2003187867A/en active Pending
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| JP2004319325A (en) * | 2003-04-17 | 2004-11-11 | Samsung Sdi Co Ltd | Lithium secondary battery and method for manufacturing lithium secondary battery |
| WO2006123811A1 (en) * | 2005-05-17 | 2006-11-23 | Teijin Limited | Separator for lithium ion secondary battery and lithium ion secondary battery |
| JPWO2006123811A1 (en) * | 2005-05-17 | 2008-12-25 | 帝人株式会社 | Lithium ion secondary battery separator and lithium ion secondary battery |
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| JP2008047398A (en) * | 2006-08-14 | 2008-02-28 | Sony Corp | Nonaqueous electrolyte secondary battery |
| WO2014046094A1 (en) | 2012-09-19 | 2014-03-27 | 旭化成株式会社 | Separator, manufacturing method thereof, and lithium ion secondary cell |
| US10811658B2 (en) | 2012-09-19 | 2020-10-20 | Asahi Kasei Kabushiki Kaisha | Separator and method of preparing the same, and lithium ion secondary battery |
| WO2016140311A1 (en) * | 2015-03-05 | 2016-09-09 | 日本電気株式会社 | Separator, manufacturing method for said separator, and lithium ion secondary battery using said separator |
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