JP2007173064A - Nonaqueous electrolyte solution secondary battery and its manufacturing method - Google Patents
Nonaqueous electrolyte solution secondary battery and its manufacturing method Download PDFInfo
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Abstract
Description
本発明は、リチウムイオンを利用する非水電解液二次電池に関し、特に高温保存特性および放電特性特性やサイクル寿命特性に優れた非水電解液二次電池およびその製造方法に関する。 The present invention relates to a non-aqueous electrolyte secondary battery using lithium ions, and more particularly to a non-aqueous electrolyte secondary battery excellent in high-temperature storage characteristics, discharge characteristics, and cycle life characteristics, and a method for manufacturing the same.
近年、民生用電子機器のポータブル化、コードレス化が急激に進んでおり、これら電子機器の駆動用電源を担う小型、軽量で高エネルギー密度を有する電池への要望が高まっている。非水電解液二次電池、とりわけリチウムイオン二次電池は、高電圧、高エネルギー密度を有する電池であることから、ノートパソコン、携帯電話、ＡＶ機器などを中心に使用されている。特にノート型パソコン等ではパソコンの内部が比較的発熱するため、リチウムイオン二次電池は高温下で長時間使用されることとなり、良好な高温保存特性および放電特性や長いサイクル寿命特性が求められる。 In recent years, consumer electronic devices have become increasingly portable and cordless, and there is an increasing demand for small, lightweight, high energy density batteries that serve as power sources for driving these electronic devices. Non-aqueous electrolyte secondary batteries, particularly lithium ion secondary batteries, are batteries having a high voltage and a high energy density, and are therefore mainly used for notebook computers, mobile phones, AV devices and the like. In particular, since notebook computers and the like generate relatively heat inside the personal computer, the lithium ion secondary battery is used at a high temperature for a long time, and good high-temperature storage characteristics, discharge characteristics, and long cycle life characteristics are required.
しかしながら、起電力が高いリチウムイオン二次電池が高温下で使用されると充放電サイクルに伴い、図３の活物質の表面に被覆層を具備しない構成を示す模式図に示したように、活物質８の表面と非水電解液が直接接触し活物質８の表面で非水電解液が分解され、ガス発生や副反応生成物の堆積によりインピーダンスが増大し、充放電特性の低下やサイクル寿命特性の劣化を引き起すという問題があった。 However, when a lithium ion secondary battery having a high electromotive force is used at a high temperature, as shown in the schematic diagram showing a configuration in which the surface of the active material in FIG. The surface of the material 8 and the non-aqueous electrolyte are in direct contact with each other, the non-aqueous electrolyte is decomposed on the surface of the active material 8, the impedance is increased by the generation of gas and by-products, the deterioration of charge / discharge characteristics and the cycle life There was a problem of causing deterioration of characteristics.
そこで図４の予め被覆層を形成した活物質を用いて作製した構成を示す模式図に示したように、活物質８の表面を無機化合物や高分子化合物で予め被覆した活物質８を用いて極板を作製する方法（例えば、特許文献１参照）により、それらの極板を用いて作製された電池において、活物質８の表面の無機化合物や高分子化合物の被覆層９により非水電解液と活物質の反応を抑制する方法が提案されている。
しかしながら、無機化合物や高分子化合物で予め被覆した活物質を用いて極板を作製した場合、次のような問題が発生する。以下、図４を参照して説明する。
（１）極板材料は練合時に大きな負荷をかけて分散させるため、被覆層９を予め形成した活物質８は、その負荷により活物質８同士が擦れ合い活物質８の表面の被覆層９が部分的に剥がれて活物質８の表面に露出部１０を生じる。そのために充放電サイクルの進行に伴い活物質８の露出部１０で非水電解液が分解され、ガス発生や副反応生成物の堆積によりインピーダンスが増大し、充放電特性の低下やサイクル寿命特性の劣化を引き起す。
（２）活物質８の表面と導電剤１１、或は活物質８同士が接触する部分にもこの被覆層９が介在するため、活物質８と導電剤１１、或は活物質８同士が直接接触できないため極板の導電性が低下し放電特性が低下する。
（３）活物質８同士や活物質８と導電剤１１が接触している活物質８自体が露出していない場所にも無機化合物や高分子化合物の被覆層９が存在しており、非水電解液の分解抑制に効果を発揮しない無駄な無機化合物や高分子化合物を含有してしまうため、電池容量の向上において不利となる。
However, when an electrode plate is produced using an active material previously coated with an inorganic compound or a polymer compound, the following problems occur. Hereinafter, a description will be given with reference to FIG.
(1) Since the electrode plate material is dispersed by applying a large load during kneading, the active material 8 in which the coating layer 9 is formed in advance is rubbed against the active material 8 by the load, and the coating layer 9 on the surface of the active material 8 Is partially peeled off to form an exposed portion 10 on the surface of the active material 8. Therefore, as the charge / discharge cycle progresses, the non-aqueous electrolyte is decomposed at the exposed portion 10 of the active material 8, the impedance increases due to gas generation and side reaction product deposition, and the charge / discharge characteristics are reduced and cycle life characteristics are reduced. Causes deterioration.
(2) Since the coating layer 9 is also present at the portion where the surface of the active material 8 and the conductive agent 11 or the active materials 8 are in contact with each other, the active material 8 and the conductive agent 11 or the active materials 8 are directly connected to each other. Since it cannot contact, the electroconductivity of an electrode plate will fall and a discharge characteristic will fall.
(3) A coating layer 9 of an inorganic compound or a polymer compound is also present in a place where the active materials 8 themselves are in contact with each other, or where the active material 8 itself where the active material 8 and the conductive agent 11 are in contact with each other. Since wasteful inorganic compounds and polymer compounds that do not exhibit the effect of suppressing the decomposition of the electrolytic solution are contained, it is disadvantageous in improving the battery capacity.
本発明は、非水電解液二次電池において、充放電サイクルに伴い極板の活物質の表面で非水電解液が分解され、ガス発生や副反応生成物の堆積によりインピーダンスが増大し、充放電特性の低下やサイクル特性の劣化を引き起す課題を解決するものであり、高容量で
且つ放電特性やサイクル寿命特性に優れた非水電解液二次電池を実現することを目的とする。
In the non-aqueous electrolyte secondary battery, the non-aqueous electrolyte is decomposed on the surface of the active material of the electrode plate during the charge / discharge cycle, and the impedance increases due to gas generation and deposition of side reaction products. An object of the present invention is to solve the problems that cause deterioration of discharge characteristics and deterioration of cycle characteristics, and to realize a non-aqueous electrolyte secondary battery having high capacity and excellent discharge characteristics and cycle life characteristics.
上記目的を達成するために本発明は、正極板と、負極板と、セパレータまたはイオン導電性層と、非水電解液とを備えた非水電解液二次電池であって、前記正極板および前記負極板の少なくともいずれか一方の活物質の前記非水電解液と接触する表面のみに、非水溶媒に不溶もしくは溶解度が極めて小さく水に可溶な化合物からなる群より選択される少なくとも一種類の化合物からなるイオンを通す被覆層を設けたことを特徴とする。 To achieve the above object, the present invention provides a non-aqueous electrolyte secondary battery comprising a positive electrode plate, a negative electrode plate, a separator or an ion conductive layer, and a non-aqueous electrolyte solution, the positive electrode plate and At least one selected from the group consisting of compounds soluble in water or insoluble in a non-aqueous solvent only on the surface of the negative electrode plate in contact with the non-aqueous electrolyte of at least one of the active materials It is characterized by providing a coating layer through which ions made of the above compound pass.
本発明によれば、正極板および負極板の少なくともいずれか一方の活物質の表面が、非水溶媒に不溶もしくは溶解度が極めて小さく水に可溶な化合物からなる群より選択される少なくとも一種類の化合物からなるイオンを通す被覆層で覆われており、その被覆層により極板の活物質の表面での非水電解液の分解が抑制されることにより、高容量で且つ放電特性やサイクル寿命特性に優れた非水電解液二次電池を提供できる。 According to the present invention, the surface of the active material of at least one of the positive electrode plate and the negative electrode plate is at least one selected from the group consisting of compounds that are insoluble in a non-aqueous solvent or have extremely low solubility and are soluble in water. It is covered with a coating layer through which ions made of a compound pass, and the coating layer suppresses the decomposition of the non-aqueous electrolyte on the surface of the active material of the electrode plate, resulting in high capacity, discharge characteristics and cycle life characteristics. It is possible to provide a non-aqueous electrolyte secondary battery that is excellent in performance.
本発明においては、正極板と、負極板と、セパレータまたはイオン導電性層と、非水電解液とを備えた非水電解液二次電池であって、前記正極板および前記負極板の少なくともいずれか一方の活物質の前記非水電解液と接触する表面のみに、非水溶媒に不溶もしくは溶解度が極めて小さく水に可溶な化合物からなる群より選択される少なくとも一種類の化合物からなるイオンを通す被覆層を設けたことを特徴とする。 In the present invention, a nonaqueous electrolyte secondary battery comprising a positive electrode plate, a negative electrode plate, a separator or an ion conductive layer, and a nonaqueous electrolyte solution, wherein at least one of the positive electrode plate and the negative electrode plate Only the surface of one of the active materials that comes into contact with the non-aqueous electrolyte has ions composed of at least one compound selected from the group consisting of compounds that are insoluble or have a very low solubility in a non-aqueous solvent. A covering layer is provided.
この構成によれば、充放電サイクルに伴い極板の活物質の表面で非水電解液が分解され、ガス発生や副反応生成物の堆積によりインピーダンスが増大する課題を解決できるため導電性に優れた、高容量で且つ放電特性やサイクル寿命特性に優れた非水電解液二次電池が得られる効果を奏する。 According to this configuration, the non-aqueous electrolyte is decomposed on the surface of the active material of the electrode plate in accordance with the charge / discharge cycle, and the problem that the impedance increases due to gas generation and deposition of side reaction products is excellent. In addition, the non-aqueous electrolyte secondary battery having a high capacity and excellent discharge characteristics and cycle life characteristics can be obtained.
また、非水溶媒に不溶もしくは溶解度が極めて小さく水に可溶な化合物は、水溶性ポリマーもしくは無機化合物を用いることが好ましい。活物質を被覆する材料として、非水溶媒に不溶もしくは溶解度が極めて小さいこれらの化合物を用いることにより、形成された活物質表面の被覆層は電池内において非水電解液へ溶解しない（もしくは非常に小さい）ことからさらに長期間の被覆効果を維持することができる。また、水に可溶な化合物であることにより、被覆する際に化合物を溶解する溶剤として水を用いることが可能である。 Moreover, it is preferable to use a water-soluble polymer or an inorganic compound as the compound that is insoluble in a non-aqueous solvent or has a very low solubility and is soluble in water. By using these compounds that are insoluble or have very low solubility in the non-aqueous solvent as the material for coating the active material, the formed active material surface coating layer does not dissolve in the non-aqueous electrolyte in the battery (or very It is possible to maintain a long-term covering effect. Moreover, since it is a compound soluble in water, it is possible to use water as a solvent for dissolving the compound when coating.
水溶性ポリマーの具体例としては、高ビニル化合物、アクリル酸系水溶性ポリマー、エチレンオキサイド系水溶性ポリマー、ビニルアルコール系水溶性ポリマー、セルロース系水溶性ポリマー、マレイン酸及びフマル酸等の不飽和カルボン酸とビニルエステルとの共重合体の鹸化物等を好ましく用いることができる。これらは単独で用いてもよく、２種以上を組み合わせて用いてもよい。 Specific examples of water-soluble polymers include high vinyl compounds, acrylic acid-based water-soluble polymers, ethylene oxide-based water-soluble polymers, vinyl alcohol-based water-soluble polymers, cellulose-based water-soluble polymers, unsaturated carboxylic acids such as maleic acid and fumaric acid. A saponified product of a copolymer of an acid and a vinyl ester can be preferably used. These may be used alone or in combination of two or more.
無機化合物の具体例としては、リチウムやナトリウム等のアルカリ金属含有無機化合物等があげられる。これらも単独で用いてもよく、２種以上を組み合わせて用いてもよい。 Specific examples of the inorganic compound include alkali metal-containing inorganic compounds such as lithium and sodium. These may be used alone or in combination of two or more.
これらの材料を用いることにより、活物質の表面での非水電解液の分解抑制効果を長期間維持可能な被膜を形成でき、放電特性やサイクル寿命特性に優れた非水電解液二次電池が得られる効果を奏する。 By using these materials, it is possible to form a coating that can maintain the effect of inhibiting decomposition of the non-aqueous electrolyte on the surface of the active material for a long period of time, and a non-aqueous electrolyte secondary battery having excellent discharge characteristics and cycle life characteristics can be obtained. The effect obtained is produced.
製造方法としては、正極板および負極板の少なくともいずれか一方の金属箔上に活物質
層を形成し、この活物質層に、非水溶媒に不溶もしくは溶解度が極めて小さく水に可溶な化合物からなる群より選択される少なくとも一種類の化合物を溶解させた水溶液を付着させる工程と、その後水分を乾燥させる工程とを含み、前記活物質層の非水電解液と接触する活物質の表面のみに前記化合物からなるイオンを通す被覆層を均一に形成させた。
As a production method, an active material layer is formed on at least one of the metal foil of the positive electrode plate and the negative electrode plate, and the active material layer is made of a compound that is insoluble in water or has a very low solubility and is soluble in water. Including a step of adhering an aqueous solution in which at least one compound selected from the group is dissolved, and a step of drying the water thereafter, and only on the surface of the active material in contact with the non-aqueous electrolyte of the active material layer A coating layer through which ions composed of the above-mentioned compound pass was uniformly formed.
この製造方法により、正極または負極活物質層の非水電解液と接触する正極活物質または負極活物質の表面のみに前記化合物からなるイオンを通す被覆層を均一に、且つ容易に形成できる。 By this manufacturing method, a coating layer that allows ions made of the above compound to pass through only the surface of the positive electrode active material or the negative electrode active material that is in contact with the non-aqueous electrolyte of the positive electrode or the negative electrode active material layer can be easily and uniformly formed.
尚、正極板、負極板とも、活物質と導電剤と結着剤とから構成されるため、図２にこれら活物質の表面のみに前記化合物からなるイオンを通す被覆層を形成した模式図を示した。よって、以下実施例の正極活物質、負極活物質は図２の活物質８に相当する。 Since both the positive electrode plate and the negative electrode plate are composed of an active material, a conductive agent, and a binder, FIG. 2 is a schematic diagram in which a coating layer that allows ions made of the above compound to pass only on the surface of these active materials. Indicated. Therefore, the positive electrode active material and the negative electrode active material in the following examples correspond to the active material 8 in FIG.
以下、図面を参照して本発明の好ましい実施例について説明する。 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
尚、ここで示す図は本発明の電池の一例であって、本発明の請求項に表す構成を有していれば、同様の効果を得ることができる。
＜実施例１＞
（電池の作成）
図１は本実施例１の非水電解液二次電池の一実施例を示す一部切欠斜視図であり、図２は本発明の活物質の露出面にのみ被覆層を具備した極板の構成を示す模式図である。
In addition, the figure shown here is an example of the battery of this invention, Comprising: If it has the structure represented to the claim of this invention, the same effect can be acquired.
<Example 1>
(Battery creation)
FIG. 1 is a partially cutaway perspective view showing an embodiment of the nonaqueous electrolyte secondary battery of Example 1, and FIG. 2 shows an electrode plate having a coating layer only on the exposed surface of the active material of the present invention. It is a schematic diagram which shows a structure.
図１に示したように、セパレータを介して帯状の正極板と負極板を複数回渦巻状に巻回して、極板群１が構成される。正極板と負極板にはそれぞれアルミニウム製の正極リード２およびニッケル製の負極リード３を接続している。それをアルミニウム製の電池ケース４内に収容する。正極リード２の他端をアルミニウム製の封口板５にスポット溶接し、また負極リード３の他端は封口板５の中心部にあるニッケル製の負極端子６の下部にスポット溶接する。電池ケース４の開口部周囲と封口板５とをレーザ溶接し、所定量の非水電解液を注入口７から注入する。最後に注入口７をアルミニウム製の栓を用いてレーザー溶接し、電池が完成する。 As shown in FIG. 1, the electrode plate group 1 is configured by winding a belt-like positive electrode plate and a negative electrode plate in a spiral shape through a separator. A positive electrode lead 2 made of aluminum and a negative electrode lead 3 made of nickel are connected to the positive electrode plate and the negative electrode plate, respectively. It is accommodated in a battery case 4 made of aluminum. The other end of the positive electrode lead 2 is spot welded to the aluminum sealing plate 5, and the other end of the negative electrode lead 3 is spot welded to the lower part of the nickel negative electrode terminal 6 at the center of the sealing plate 5. The periphery of the opening of the battery case 4 and the sealing plate 5 are laser welded, and a predetermined amount of non-aqueous electrolyte is injected from the inlet 7. Finally, the inlet 7 is laser welded using an aluminum stopper to complete the battery.
（１）正極板の作製
ＬｉＣｏ0.94Ｍｇ0.05Ａｌ0.01Ｏ2を正極活物質とした。この正極活物質１００重量部に導電剤１１としてアセチレンブラック３重量部、結着剤１２としてポリフッ化ビニリデンが５重量部になるようにポリフッ化ビニリデンのＮ−メチルピロリジノン溶液を調整し、撹拌混合してペースト状の正極合剤を得た。次に、厚さ２０μｍのアルミニウム箔を集電体とし、その両面に前記ペースト状正極合剤を塗布し、乾燥後圧延ローラーで圧延を行い、所定寸法に裁断して正極板とした。
(1) Production of positive electrode plate LiCo 0.94 Mg 0.05 Al 0.01 O 2 was used as a positive electrode active material. An N-methylpyrrolidinone solution of polyvinylidene fluoride is adjusted to 100 parts by weight of the positive electrode active material so that 3 parts by weight of acetylene black as the conductive agent 11 and 5 parts by weight of polyvinylidene fluoride as the binder 12 are mixed with stirring. Thus, a paste-like positive electrode mixture was obtained. Next, an aluminum foil having a thickness of 20 μm was used as a current collector, the paste-like positive electrode mixture was applied to both surfaces thereof, dried and then rolled with a rolling roller, and cut into predetermined dimensions to obtain a positive electrode plate.
尚、正極用の導電剤１１としては、構成された電池において実質的に化学安定な電子伝導性材料であればよい。例えば、グラファイト類、カーボンブラック類、導電性繊維類、金属粉末類、導電性ウィスカー類、導電性金属酸化物あるいはポリフェニレン誘導体などの有機導電性材料などが挙げられ、これらを単独または混合物として用いても良い。 The conductive agent 11 for the positive electrode only needs to be an electron conductive material that is substantially chemically stable in the constructed battery. Examples include graphites, carbon blacks, conductive fibers, metal powders, conductive whiskers, organic conductive materials such as conductive metal oxides or polyphenylene derivatives, and these are used alone or as a mixture. Also good.
正極用の結着剤１２としては、熱可塑性樹脂、熱硬化性樹脂などが用いられる。例えば、ポリフッ化ビニリデン（ＰＶＤＦ）の他、ポリテトラフルオロエチレン（ＰＴＦＥ）などが好ましい。 As the positive electrode binder 12, a thermoplastic resin, a thermosetting resin, or the like is used. For example, polytetrafluoroethylene (PTFE) is preferable in addition to polyvinylidene fluoride (PVDF).
（２）負極板の作製
平均粒径が約２０μｍになるように粉砕、分級した鱗片状黒鉛１００重量部と結着剤１２のスチレンブタジエンゴム３重量部を混合した後、黒鉛に対しカルボキシメチルセルロースが１％となるようにカルボキシメチルセルロ−ス水溶液を加え、撹拌混合しペースト状負極合剤とした。厚さ１５μｍの銅箔を集電体とし、その両面にペースト状の負極合剤を塗布し、乾燥後圧延ローラーを用いて圧延を行い、所定寸法に裁断して負極板とした。
(2) Production of negative electrode plate After mixing 100 parts by weight of flaky graphite pulverized and classified so as to have an average particle size of about 20 μm and 3 parts by weight of styrene butadiene rubber of binder 12, carboxymethyl cellulose is added to graphite. A carboxymethyl cellulose aqueous solution was added so as to be 1%, and the mixture was stirred and mixed to obtain a paste-like negative electrode mixture. A copper foil having a thickness of 15 μm was used as a current collector, a paste-like negative electrode mixture was applied to both surfaces thereof, dried and then rolled using a rolling roller, and cut into a predetermined size to obtain a negative electrode plate.
尚、負極活物質としては、例えばリチウムをドープ・脱ドープすることが可能な炭素質を主体とする材料として、熱分解炭素類、コークス類（ピッチコークス、ニードルコークス、石油コークス等）、グラファイト類、ガラス状炭素類、有機高分子化合物焼成体（フェノール樹脂、フラン樹脂等を適当な温度で焼成し炭素化したもの）、炭素繊維、活性炭素等が挙げられ、これらを単独もしくは２種以上を混合して用いることができる。負極活物質の平均粒径は特に限定されないが、１〜３０μｍのものが好ましい。 Examples of the negative electrode active material include pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, and the like, which are mainly carbonaceous materials that can be doped and dedoped with lithium. , Glassy carbons, organic polymer compound fired bodies (phenol resins, furan resins, etc., fired at a suitable temperature and carbonized), carbon fibers, activated carbon, etc., and these may be used alone or in combination of two or more. It can be used by mixing. The average particle diameter of the negative electrode active material is not particularly limited, but is preferably 1 to 30 μm.
負極用の導電剤１１としては、電子伝導性材料であれば特に限定されないが、例えば、人造黒鉛、アセチレンブラック、炭素繊維などが好ましい。 The conductive agent 11 for the negative electrode is not particularly limited as long as it is an electron conductive material. For example, artificial graphite, acetylene black, carbon fiber, and the like are preferable.
負極用の結着剤１２としては、スチレンブタジエンゴム、ポリフッ化ビニリデン、エチレン−アクリル酸共重合体または前記材料の（Ｎａ+）イオン架橋体、エチレン−メタクリル酸共重合体または前記材料の（Ｎａ+）イオン架橋体、エチレン−アクリル酸メチル共重合体または前記材料の（Ｎａ+）イオン架橋体、エチレン−メタクリル酸メチル共重合体または前記材料の（Ｎａ+）イオン架橋体などが好ましい。 As the binder 12 for the negative electrode, styrene butadiene rubber, polyvinylidene fluoride, ethylene-acrylic acid copolymer or (Na +) ion crosslinked product of the above material, ethylene-methacrylic acid copolymer or (Na of the material) A +) ion-crosslinked product, an ethylene-methyl acrylate copolymer, or a (Na +) ion-crosslinked product of the material, an ethylene-methyl methacrylate copolymer, or a (Na +) ion-crosslinked product of the material is preferable.
（３）水溶液の調製
（表１）に示した各化合物の水溶液１〜９を作製した。
(3) Preparation of aqueous solution The aqueous solutions 1-9 of each compound shown in (Table 1) were produced.
エチレンカーボネートとエチルメチルカーボネートを２０℃において３０：７０の体積割合で調整した溶媒に１．０ｍｏｌ／ｌのＬｉＰＦ6を溶解したものを用いた。
（５）電池の組立
（実施例１の電池Ａ１〜Ａ９）
前記（３）で調整した各化合物の水溶液１〜９を、（１）の正極板の合剤層にグラビア塗布し、その後水分を温風乾燥させて、図２に示したような活物質８の露出面にのみ被覆層９を具備した正極板を作製した。そして、被覆層９を具備した正極板と、負極板および厚さ２５μｍの微多孔性ポリエチレン樹脂製のセパレータを渦巻状に巻回し、これに前記（４）で調整した非水電解液を注液した後密封栓した。このようにして作製した電池を本発明の実施例１の電池Ａ１からＡ９とした。
(5) Battery assembly (Batteries A1 to A9 of Example 1)
The aqueous solutions 1 to 9 of the respective compounds prepared in the above (3) are gravure-coated on the mixture layer of the positive electrode plate in (1), and then the water is dried with hot air, so that the active material 8 as shown in FIG. A positive electrode plate having a coating layer 9 only on the exposed surface was prepared. Then, the positive electrode plate provided with the coating layer 9, the negative electrode plate, and a separator made of a microporous polyethylene resin having a thickness of 25 μm are wound in a spiral shape, and the nonaqueous electrolytic solution prepared in the above (4) is injected into this. And then sealed. The batteries thus produced were designated as batteries A1 to A9 of Example 1 of the present invention.
（実施例１の電池Ｂ１〜Ｂ９）
負極板の合剤層に、前記（３）で調整した各化合物の水溶液１〜９を塗布した以外は電池Ａ１〜Ａ９と同様にして作製した電池を本発明の実施例１の電池Ｂ１〜Ｂ９とした。
(Batteries B1 to B9 of Example 1)
Batteries produced in the same manner as the batteries A1 to A9, except that the aqueous solutions 1 to 9 of the respective compounds prepared in (3) were applied to the mixture layer of the negative electrode plate, the batteries B1 to B9 of Example 1 of the present invention. It was.
（実施例１の電池Ｃ１〜Ｃ９）
正極板および負極板の両合剤層に、前記（３）で調整した各化合物の水溶液１〜９を塗布した以外は電池Ａ１〜Ａ９と同様にして作製した電池を本発明の実施例１の電池Ｃ１〜Ｃ９とした。
(Batteries C1 to C9 of Example 1)
A battery produced in the same manner as the batteries A1 to A9, except that the aqueous solutions 1 to 9 of the respective compounds prepared in (3) above were applied to both the mixture layers of the positive electrode plate and the negative electrode plate, was used in Example 1 of the present invention. The batteries C1 to C9 were used.
（比較例の電池Ｄ）
前記（３）で調整した各化合物の水溶液を塗布せず、図３に示したように被覆層を具備しない正極板および負極板を作製した以外は、実施例１と同様にして作製した電池を比較例の電池Ｄとした。
(Comparative battery D)
A battery produced in the same manner as in Example 1 except that the aqueous solution of each compound prepared in (3) above was not applied and a positive electrode plate and a negative electrode plate not provided with a coating layer were produced as shown in FIG. A battery D of Comparative Example was obtained.
（比較例の電池Ｅ、Ｆ）
正極活物質および負極活物質のそれぞれに、予め炭酸リチウムおよびポリアクリル酸ナトリウムで被覆処理を行い、図４に示したような正極板および負極板を得た以外は、比較例Dと同様にして作製した電池を比較例の電池Ｅおよび電池Ｆとした。
(Comparison batteries B and E)
Each of the positive electrode active material and the negative electrode active material was previously coated with lithium carbonate and sodium polyacrylate to obtain a positive electrode plate and a negative electrode plate as shown in FIG. The produced batteries were referred to as Comparative Example Battery E and Battery F.
（サイクル寿命特性評価）
実施例１および比較例の電池Ｄ〜Ｆを用い、環境温度２０℃で充放電サイクルを５００回行った。充電条件は最大電流６００ｍＡ、充電終止電位が４．２０Ｖでの定電圧充電を２時間とした。放電条件は電流値６００ｍＡ、放電終止電位３．０Ｖの定電流で行い、５００サイクル経過後の放電容量を測定し、初期容量に対する比率で評価結果を示した。
(Cycle life characteristics evaluation)
Using the batteries D to F of Example 1 and Comparative Example, the charge / discharge cycle was performed 500 times at an environmental temperature of 20 ° C. The charging conditions were a constant voltage charge at a maximum current of 600 mA and a charge end potential of 4.20 V for 2 hours. The discharge conditions were a constant current with a current value of 600 mA and a discharge end potential of 3.0 V, the discharge capacity after 500 cycles had been measured, and the evaluation results were shown as a ratio to the initial capacity.
（放電特性評価）
実施例１および比較例の電池Ｄ〜Ｆを用い、環境温度２０℃、および０℃で電池容量測定を行った。充電条件は最大電流６００ｍＡ、充電終止電位が４．２０Ｖでの定電圧充電を２時間とした。放電条件は電流値６００ｍＡ、放電終止電位３．０Ｖの定電流で行い、それぞれの電池の放電容量を測定した。それぞれの電池において、２０℃の放電容量に対する０℃の放電容量を比率で表し比較を行った。
(Discharge characteristic evaluation)
Using the batteries D to F of Example 1 and Comparative Example, the battery capacity was measured at an environmental temperature of 20 ° C. and 0 ° C. The charging conditions were constant voltage charging with a maximum current of 600 mA and a charge end potential of 4.20 V for 2 hours. The discharge conditions were a constant current with a current value of 600 mA and a discharge end potential of 3.0 V, and the discharge capacity of each battery was measured. In each battery, the discharge capacity at 0 ° C. with respect to the discharge capacity at 20 ° C. was expressed as a ratio and compared.
（表２）に実施例１の電池Ａ１〜Ａ９，Ｂ１〜Ｂ９，Ｃ１〜Ｃ９、（表３）に比較例の電池Ｄ〜Ｆの５００サイクル後容量維持率、および放電特性の評価結果を示す。 (Table 2) shows the battery A1 to A9, B1 to B9, C1 to C9 of Example 1, and (Table 3) shows the capacity retention rate after 500 cycles and the evaluation results of the discharge characteristics of the batteries D to F of the comparative example. .
一方、（表３）からわかる通り、図３に示したような活物質８の表面に被覆層を具備しない比較例の電池Ｄの容量維持率は３１％と大きく低下した。また、活物質の状態で予め被覆処理を施し、図４に示したような活物質８の表面に露出部１０を生じた比較例の電池Ｅ，Ｆの容量維持率は各々５８％，６１％となり、比較例の電池Ｄに比べれば改善されているものの実施例１の電池ほどの改善効果は認められなかった。 On the other hand, as can be seen from (Table 3), the capacity retention rate of the battery D of Comparative Example which does not have a coating layer on the surface of the active material 8 as shown in FIG. Further, the capacity retention ratios of the batteries E and F of Comparative Examples in which the exposed portion 10 was generated on the surface of the active material 8 as shown in FIG. Thus, although improved compared to the battery D of the comparative example, the improvement effect as the battery of Example 1 was not recognized.
容量維持率の低下が大きい５００サイクル後の比較例の電池Ｄを分解し観察を行った結果、極板の表面で明らかに非水電解液が涸渇している部位が認められた。そのような部位周辺の正極板のＸ線回折分析を行うと、正極活物質の結晶構造が変化しており充電の不均一化が発生して正極活物質が顕著に劣化していることがわかった。そのような部位周辺の負極板においては、充電の不均一化によりリチウム析出が認められた。また、活物質の状態で予め被覆処理を施した比較例の電池Ｅを同様に分解し観察を行った結果、比較例の電池Ｄに比べれば非水の涸渇は抑制されているが、正極のＸ線回折分析によれば正極活物質の結晶構造に少なからず変化が認められ、負極板においてもリチウム析出が認められた。これは活物質の状態で形成された被覆層が極板を作製するまでの工程、特に練合時に大き
な負荷がかかり被覆層が剥離したことが原因と考えられる。
As a result of disassembling and observing the battery D of the comparative example after 500 cycles in which the decrease in the capacity retention rate was large, a portion where the nonaqueous electrolyte was clearly depleted was observed on the surface of the electrode plate. When X-ray diffraction analysis of the positive electrode plate around such a part is performed, it is found that the crystal structure of the positive electrode active material has changed, the charge becomes non-uniform, and the positive electrode active material has deteriorated significantly. It was. In the negative electrode plate around such a region, lithium deposition was observed due to nonuniform charging. In addition, as a result of similarly disassembling and observing the battery E of the comparative example that was previously coated in the active material state, non-water depletion was suppressed as compared with the battery D of the comparative example. According to the X-ray diffraction analysis, a considerable change was observed in the crystal structure of the positive electrode active material, and lithium deposition was also observed in the negative electrode plate. This is presumably because the coating layer formed in the state of the active material was subjected to a process until the electrode plate was produced, particularly when a large load was applied during kneading and the coating layer was peeled off.
正極板および負極板の両方に被覆処理をした５００サイクル後の実施例１の電池Ｃ２を分解し観察を行った結果、極板の表面で非水電解液が涸渇している部位は認められなかった。正極板のＸ線回折分析によれば正極活物質の結晶構造に顕著な変化はなく、負極板においてもリチウム析出は認められなかった。 As a result of disassembling and observing the battery C2 of Example 1 after 500 cycles in which both the positive electrode plate and the negative electrode plate were coated, a portion where the nonaqueous electrolyte was depleted on the surface of the electrode plate was not recognized. It was. According to the X-ray diffraction analysis of the positive electrode plate, there was no significant change in the crystal structure of the positive electrode active material, and no lithium deposition was observed in the negative electrode plate.
放電特性（０℃／２５℃）の評価結果は、実施例１の電池Ａ１〜Ａ９，Ｂ１〜Ｂ９，Ｃ１〜Ｃ９および比較例の電池Ｄが７９％〜８４％と良好であったのに比べ、比較例の電池Ｅ，Ｆが各々６６％，６４％と明かに放電特性の低下が認められた。比較例の電池Ｅ，Ｆは、図４に示したように活物質８同士或は活物質８と導電剤１１が接触する部分にも被覆層９が介在し導電性が低下したため放電特性の低下を引き起こしたと考えられる。極板作製後に被覆処理を施した実施例１の電池Ａ１〜Ａ９，Ｂ１〜Ｂ９，Ｃ１〜Ｃ９および被覆処理を施していない比較例の電池Ｄは、放電特性の低下は認められなかった。実施例１の電池は、図２に示したように極板状態において非水電解液と接触する活物質８の表面にのみ被覆層９が存在しており、活物質８同士或は活物質８と導電剤１１の直接の接触が維持されていることにより放電特性が良好であったと考えられる。比較例の電池Ｄは図３に示したように活物質８の表面に被覆層を具備しないため導電性が確保され、初期の放電特性は良好であったと考えられる。 The evaluation results of the discharge characteristics (0 ° C./25° C.) were higher than those in which the batteries A1 to A9, B1 to B9, C1 to C9 of Example 1 and the battery D of the comparative example were 79% to 84%. The batteries E and F of the comparative example clearly showed a decrease in discharge characteristics of 66% and 64%, respectively. As shown in FIG. 4, the batteries E and F of the comparative examples have a decrease in discharge characteristics because the covering layer 9 is also interposed between the active materials 8 or portions where the active material 8 and the conductive agent 11 are in contact with each other. It is thought that caused. In the batteries A1 to A9, B1 to B9, C1 to C9 of Example 1 subjected to the coating treatment after the electrode plate was produced, and the battery D of the comparative example not subjected to the coating treatment, no deterioration in discharge characteristics was observed. In the battery of Example 1, as shown in FIG. 2, the coating layer 9 exists only on the surface of the active material 8 in contact with the non-aqueous electrolyte in the electrode plate state. It is considered that the discharge characteristics were good because the direct contact between the conductive material 11 and the conductive agent 11 was maintained. As shown in FIG. 3, the battery D of the comparative example does not have a coating layer on the surface of the active material 8, so that conductivity is ensured and the initial discharge characteristics are considered good.
以上の結果より、実施例１においては活物質８の非水電解液と接触する表面にのみ被覆層９を具備することにより、充放電サイクルにおける活物質８の表面での非水電解液の分解が抑制され、サイクルを経ても非水電解液の涸渇が起こらず、充放電に伴う極板の反応の均一性が保たれることから活物質８が劣化せず、良好なサイクル寿命特性が得られることがわかった。また、活物質８の状態で予め被覆処理を施した場合と比べて、放電特性の低下を引き起こすこともないことがわかった。 From the above results, in Example 1, the coating layer 9 is provided only on the surface of the active material 8 in contact with the non-aqueous electrolyte solution, so that the non-aqueous electrolyte solution is decomposed on the surface of the active material 8 in the charge / discharge cycle. And the non-aqueous electrolyte is not depleted even after cycling, and the uniformity of the reaction of the electrode plate during charging and discharging is maintained, so that the active material 8 does not deteriorate and good cycle life characteristics are obtained. I found out that Moreover, it turned out that it does not cause the fall of a discharge characteristic compared with the case where a coating process is performed previously in the state of the active material 8.
さらに、活物質８同士や活物質８と導電剤１１が接触している活物質８自体が露出していない場所に無機化合物や高分子化合物の被覆層９が存在せず、非水電解液の分解抑制に効果を発揮しない無駄な無機化合物や高分子化合物を含有しないため、電池容量の向上において有利となることは明白である。 Furthermore, the coating layer 9 of the inorganic compound or the polymer compound does not exist in a place where the active materials 8 themselves are in contact with each other, or the active material 8 itself where the active material 8 and the conductive agent 11 are in contact with each other. It is clear that it is advantageous in improving battery capacity because it does not contain useless inorganic compounds and polymer compounds that do not exhibit the effect of inhibiting decomposition.
本発明にかかる非水電解液二次電池は、高容量で且つ放電特性やサイクル寿命特性に優れるので非水電解液二次電池として有用である。 The non-aqueous electrolyte secondary battery according to the present invention is useful as a non-aqueous electrolyte secondary battery because of its high capacity and excellent discharge characteristics and cycle life characteristics.
１ 極板群
２ 正極リード
３ 負極リード
４ 電池ケース
５ 封口板
６ 負極端子
７ 注入口
８ 活物質
９ 被覆層
１０ 露出部
１１ 導電剤
１２ 結着剤
DESCRIPTION OF SYMBOLS 1 Electrode plate group 2 Positive electrode lead 3 Negative electrode lead 4 Battery case 5 Sealing plate 6 Negative electrode terminal 7 Inlet 8 Active material 9 Covering layer 10 Exposed part 11 Conductive agent 12 Binder
Claims (4)
前記正極板、前記負極板の少なくともいずれか一方の活物質の前記非水電解液と接触する表面のみに、非水溶媒に不溶もしくは溶解度が極めて小さく水に可溶な化合物からなる群より選択される少なくとも一種類の化合物からなるイオンを通す被覆層を設けた非水電解液二次電池。 A non-aqueous electrolyte secondary battery comprising a positive electrode plate, a negative electrode plate, a separator or an ion conductive layer, and a non-aqueous electrolyte solution,
The active material of at least one of the positive electrode plate and the negative electrode plate is selected from the group consisting of a compound that is insoluble in a non-aqueous solvent or has a very low solubility and is soluble in water only on the surface in contact with the non-aqueous electrolyte. A nonaqueous electrolyte secondary battery provided with a coating layer through which ions made of at least one kind of compound pass.
前記正極板および前記負極板の少なくともいずれか一方の金属箔上に活物質層を形成し、この活物質層に非水溶媒に不溶もしくは溶解度が極めて小さく水に可溶な化合物からなる群より選択される少なくとも一種類の化合物を溶解させた水溶液を付着させる工程と、その後水分を乾燥させる工程とを含み、前記活物質層の前記非水電解液と接触する活物質の表面のみに前記化合物からなるイオンを通す被覆層を形成させる非水電解液二次電池の製造方法。
A method for producing a non-aqueous electrolyte secondary battery comprising a positive electrode plate, a negative electrode plate, a separator or ion conductive layer, and a non-aqueous electrolyte solution,
An active material layer is formed on at least one metal foil of the positive electrode plate and the negative electrode plate, and the active material layer is selected from the group consisting of compounds that are insoluble in a non-aqueous solvent or have extremely low solubility and are soluble in water. A step of adhering an aqueous solution in which at least one kind of compound is dissolved, and a step of drying the water thereafter, from the compound only on the surface of the active material in contact with the non-aqueous electrolyte of the active material layer The manufacturing method of the non-aqueous-electrolyte secondary battery which forms the coating layer which lets the ion which becomes.
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| JP2009037891A (en) * | 2007-08-02 | 2009-02-19 | Panasonic Corp | Lithium-ion secondary battery |
| JP2009245921A (en) * | 2008-03-13 | 2009-10-22 | Denso Corp | Electrode for secondary battery, method of manufacturing the same, and secondary battery employing the same |
| JP2010108679A (en) * | 2008-10-29 | 2010-05-13 | Panasonic Corp | Electrode group for nonaqueous secondary battery and nonaqueous secondary battery using the same |
| CN101872860A (en) * | 2009-04-22 | 2010-10-27 | 索尼公司 | Positive active material, its manufacture method and nonaqueous electrolyte battery |
| JP2012079493A (en) * | 2010-09-30 | 2012-04-19 | Sekisui Chem Co Ltd | Electrode for lithium-ion secondary battery and lithium-ion secondary battery |
| JP2012164624A (en) * | 2011-01-20 | 2012-08-30 | Toyota Industries Corp | Negative electrode active material for lithium ion secondary battery, and lithium ion secondary battery comprising the negative electrode active material |
| JP2012248441A (en) * | 2011-05-30 | 2012-12-13 | Hitachi Maxell Energy Ltd | Cathode active material and cathode for lithium ion secondary battery and lithium ion secondary battery using the same |
| JP2018061021A (en) * | 2016-09-30 | 2018-04-12 | 旭化成株式会社 | Nonaqueous alkali metal type power storage element |
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2005
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| JP2009037891A (en) * | 2007-08-02 | 2009-02-19 | Panasonic Corp | Lithium-ion secondary battery |
| JP2009245921A (en) * | 2008-03-13 | 2009-10-22 | Denso Corp | Electrode for secondary battery, method of manufacturing the same, and secondary battery employing the same |
| JP2010108679A (en) * | 2008-10-29 | 2010-05-13 | Panasonic Corp | Electrode group for nonaqueous secondary battery and nonaqueous secondary battery using the same |
| CN101872860A (en) * | 2009-04-22 | 2010-10-27 | 索尼公司 | Positive active material, its manufacture method and nonaqueous electrolyte battery |
| JP2012079493A (en) * | 2010-09-30 | 2012-04-19 | Sekisui Chem Co Ltd | Electrode for lithium-ion secondary battery and lithium-ion secondary battery |
| JP2012164624A (en) * | 2011-01-20 | 2012-08-30 | Toyota Industries Corp | Negative electrode active material for lithium ion secondary battery, and lithium ion secondary battery comprising the negative electrode active material |
| JP2012248441A (en) * | 2011-05-30 | 2012-12-13 | Hitachi Maxell Energy Ltd | Cathode active material and cathode for lithium ion secondary battery and lithium ion secondary battery using the same |
| US8685573B2 (en) | 2011-05-30 | 2014-04-01 | Hitachi Maxell, Ltd. | Cathode active material and lithium ion rechargeable battery using the material |
| JP2018061021A (en) * | 2016-09-30 | 2018-04-12 | 旭化成株式会社 | Nonaqueous alkali metal type power storage element |
| JP7057085B2 (en) | 2016-09-30 | 2022-04-19 | 旭化成株式会社 | Non-aqueous alkali metal type power storage element |
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