【０００１】[0001]
【発明の属する技術分野】本発明は、リチウムイオン二
次電池等の蓄電池、あるいは電気二重層キャパシタ等の
蓄電装置全般に属する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery such as a lithium ion secondary battery or a power storage device such as an electric double layer capacitor.
【０００２】[0002]
【従来の技術】一般に電気化学電池の構造は、正極及び
負極と、両極間に介在する電解質とを備え、これらが電
池ケースに収容されている。電池ケースには安全弁が設
けられて、爆発時に安全弁のみが破裂してケース全体の
飛散を防止している。電解質が液体の場合は、正負両極
の短絡防止のための多孔質のセパレータが両極間に介在
させられ、そのセパレータの気孔内部に電解液が浸透さ
せられる。固体電解質の場合は、それが両極の間隔を維
持するので、セパレータに代わって短絡防止機能も有す
る。いずれの場合も正極及び負極は、電気化学反応に直
接関与する活物質、あるいは電気化学反応に関与するイ
オンを吸蔵及び放出する物質（以下、「ホスト物質」と
いう。）に結着剤などを混ぜ合わせた合剤を導電性の正
極又は負極の集電体に保持したものとされる。2. Description of the Related Art Generally, an electrochemical battery has a structure including a positive electrode, a negative electrode, and an electrolyte interposed between the two electrodes, which are housed in a battery case. A safety valve is provided in the battery case, and only the safety valve ruptures in the event of an explosion to prevent the entire case from scattering. When the electrolyte is a liquid, a porous separator for preventing a short circuit between the positive and negative electrodes is interposed between the electrodes, and the electrolytic solution penetrates into the pores of the separator. In the case of a solid electrolyte, it also has a function of preventing short-circuiting in place of the separator since it maintains the distance between the electrodes. In each case, the positive electrode and the negative electrode are prepared by mixing a binder and the like with an active material directly involved in the electrochemical reaction or a material that absorbs and releases ions involved in the electrochemical reaction (hereinafter, referred to as a “host substance”). The combined mixture is held on a conductive positive or negative electrode current collector.
【０００３】例えば、近年携帯電話、携帯用パソコン等
の小型携帯電子機器用の電源として広範な利用が期待さ
れているリチウムイオン電池においては、リチウムイオ
ンを吸蔵及び放出できる炭素をホスト物質として含む負
極合剤を負極集電体に保持してなる負極板と、リチウム
コバルト複合酸化物やリチウムニッケル複合酸化物のよ
うにリチウムイオンと可逆的に電気化学反応をする正極
活物質を含む正極合剤を正極集電体に保持してなる正極
板と、電解質を保持するとともに負極板と正極板との間
に介在して両極の短絡を防止するセパレータとを備えて
いる。電解質は通常ＬｉＣｌＯ4、ＬｉＰＦ6等のリチウ
ム塩を溶解した非プロトン性の有機溶媒からなるが、固
体電解質でも良い。ただし、電解質が固体の場合は前述
の通りセパレータは必須でない。極板の集電体として
は、それ自体の導電性が必要であることから、銅、アル
ミニウムなどの金属の箔が一般的に用いられている。For example, in a lithium ion battery, which is expected to be widely used as a power source for small portable electronic devices such as mobile phones and portable personal computers in recent years, a negative electrode containing carbon capable of occluding and releasing lithium ions as a host material has been proposed. A negative electrode plate holding the mixture on the negative electrode current collector and a positive electrode mixture containing a positive electrode active material that reversibly electrochemically reacts with lithium ions, such as a lithium cobalt composite oxide or a lithium nickel composite oxide. A positive electrode plate held by a positive electrode current collector and a separator that holds an electrolyte and is interposed between the negative electrode plate and the positive electrode plate to prevent a short circuit between the two electrodes are provided. The electrolyte is usually made of an aprotic organic solvent in which a lithium salt such as LiClO4 or LiPF6 is dissolved, but may be a solid electrolyte. However, when the electrolyte is solid, the separator is not essential as described above. As the current collector of the electrode plate, a metal foil such as copper or aluminum is generally used because the current collector itself is required.
【０００４】一方、ＩＣやメモリのバックアップ用の小
電力直流電源として使用されている電気二重層キャパシ
タの場合、その構成は、活性炭のような表面積の大きい
材料と結着剤とで成形した２枚の電極を、多孔質のセパ
レータを介して対向させて配置し、セパレータに電解液
を浸透させたものである。On the other hand, in the case of an electric double-layer capacitor used as a low-power DC power supply for backup of ICs and memories, its structure is composed of two sheets formed of a material having a large surface area such as activated carbon and a binder. Are disposed facing each other with a porous separator interposed therebetween, and the separator is impregnated with an electrolytic solution.
【０００５】[0005]
【発明が解決しようとする課題】しかし、電気化学電池
にしろ電気二重層キャパシタにしろ、電極材料はいずれ
も上記の如く粉末であるから、たとえ板状に成形されて
いても、極表面においては凹凸を有する。このためセパ
レータと電極との間隔は厳密には電極の面方向に一様で
はない。その結果、面方向で充放電時の電流分布が異な
り、例えば負極の充電時にセパレータとの間隔が狭い部
分では完全充電となっていても電極全体としては完全充
電となっていないので、充電が続けられ、局部的に過充
電となる。そして、電極や電解質の種類にもよるが、過
充電は電解液の分解やリチウム金属の電析（リチウム電
池の場合）等の不可逆反応を伴い、容量を低下させる。
また、電析したリチウム金属は、放電しないから異常高
温時に溶けて正極へ移動し爆発する危険がある。そこ
で、従来は局部的な過充電を防止するために、充電容量
を負極の理論容量の６０〜８０％に抑制しなければなら
なかった。それ故、本発明の目的は、従来のセパレータ
と異なる構成により、高容量で安全な蓄電装置を提供す
ることにある。However, regardless of whether it is an electrochemical cell or an electric double layer capacitor, the electrode material is a powder as described above, so that even if it is formed into a plate, the electrode material is not It has irregularities. Therefore, the distance between the separator and the electrode is not strictly uniform in the surface direction of the electrode. As a result, the current distribution at the time of charge / discharge differs in the plane direction.For example, when the negative electrode is charged, even if the space between the separator and the separator is small, the electrode is not fully charged even if it is fully charged. Is locally overcharged. And, depending on the type of electrodes and electrolyte, overcharging involves irreversible reactions such as decomposition of the electrolytic solution and electrodeposition of lithium metal (in the case of lithium batteries), and reduces the capacity.
Further, since the deposited lithium metal does not discharge, it melts at an abnormally high temperature, moves to the positive electrode, and may explode. Therefore, conventionally, in order to prevent local overcharge, the charging capacity has to be suppressed to 60 to 80% of the theoretical capacity of the negative electrode. Therefore, an object of the present invention is to provide a high-capacity and safe power storage device having a configuration different from a conventional separator.
【０００６】[0006]
【課題を解決するための手段】その目的を達成するため
に、本発明の蓄電装置は、正負の電極と、これら電極の
間に存在して電極の間隔を定めるとともに電解質を保持
する多孔質のセパレータとを備えた蓄電装置において、
セパレータの気孔率が、正極側から負極側に向かって減
少していることを特徴とする。In order to achieve the object, a power storage device of the present invention comprises a positive electrode and a negative electrode, and a porous electrode which is located between the electrodes to determine an interval between the electrodes and to hold an electrolyte. In a power storage device including a separator,
The porosity of the separator decreases from the positive electrode side to the negative electrode side.
【０００７】本発明の作用を図面とともに説明する。図
１は、蓄電装置の負極とセパレータとの界面を示す断面
図である。既述の通り、負極１の極表面は凹凸を有す
る。また、セパレータ２の気孔率は負極に近づくに連れ
て減少しているが、図示及び説明の便宜上、図面では負
極１に近づくに連れて気孔３の内径を小さくしてある。
従って、セパレータ２の負極側表面付近の抵抗は、セパ
レータ２と負極１との凹凸状の間隔の抵抗よりも大き
い。このため、充電時にセパレータの気孔内部を正極か
ら負極に向かう正電荷（Ｌｉ+等）の移動は、セパレー
タの負極側表面が律速段階となり、そこで電流分布が均
一化される。その結果、局部的な過充電がなくなり充電
容量を増やすことができる。リチウムイオン二次電池に
おいて、万一リチウムイオンが電析しても、電析によっ
て負極に生じるリチウム金属は面方向に均一で微細なも
のに止まり、放電可能である。従って、安全である。The operation of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating an interface between a negative electrode of a power storage device and a separator. As described above, the surface of the negative electrode 1 has irregularities. Although the porosity of the separator 2 decreases as it approaches the negative electrode, the inside diameter of the pore 3 decreases as it approaches the negative electrode 1 in the drawings for convenience of illustration and description.
Therefore, the resistance in the vicinity of the negative electrode side surface of the separator 2 is larger than the resistance of the uneven space between the separator 2 and the negative electrode 1. For this reason, the movement of positive charges (such as Li+ ) from the positive electrode to the negative electrode in the pores of the separator during charging is limited on the negative electrode side surface of the separator, where the current distribution is uniformed. As a result, local overcharge does not occur and the charge capacity can be increased. In a lithium ion secondary battery, even if lithium ions are electrodeposited, the lithium metal generated on the negative electrode by the electrodeposition remains uniform and fine in the plane direction and can be discharged. Therefore, it is safe.
【０００８】これに対し、従来の蓄電装置は、セパレー
タの気孔分布が一様であるから、負極側表面が電荷移動
の律速段階とならない。そのため、セパレータと負極と
の間隔が狭い部分（図中の一点鎖線Ａの範囲）で局部的
に完全充電されているのに、間隔が広い部分（図中の一
点鎖線Ｂの範囲）では充電不足であるから、充電が続け
られる。その結果、Ａの部分で局部的に過充電となる。On the other hand, in the conventional power storage device, since the pore distribution of the separator is uniform, the surface of the negative electrode does not become a rate-determining stage of the charge transfer. For this reason, the battery is partially and fully charged in a portion where the distance between the separator and the negative electrode is small (the range of the dashed line A in the figure), but is insufficiently charged in a portion where the distance is large (the range of the dashed line B in the drawing). Therefore, charging is continued. As a result, overcharging occurs locally at the portion A.
【０００９】[0009]
【発明の実施の形態】前記セパレータは、例えばポリプ
ロピレンやポリエチレン等の有機高分子からなる多孔質
フィルムであり、それに電解液が浸透させられる。電解
質としてポリフッ化ビニリデン、ポリアクリロニトリル
等の固体電解質を用いる場合は、それ自体が電極の間隔
を定めてセパレータを兼ねるので、別個のセパレータは
必要でない。ただし、その場合も電解液を固体電解質に
浸透させておくと電池反応の効率上良い。DESCRIPTION OF THE PREFERRED EMBODIMENTS The separator is a porous film made of an organic polymer such as polypropylene or polyethylene, and an electrolyte is permeated therein. When a solid electrolyte such as polyvinylidene fluoride or polyacrylonitrile is used as the electrolyte, a separate separator is not required because the electrolyte itself determines the interval between the electrodes and also functions as a separator. However, also in this case, it is effective in terms of the efficiency of the battery reaction if the electrolyte is allowed to penetrate the solid electrolyte.
【００１０】前記蓄電装置として好適なものは、リチウ
ムイオン二次電池である。本発明によりリチウムイオン
の電析が防止されるか又は電析しても均一で微量に止ま
るからである。また、前記蓄電装置は電気二重層キャパ
シタであっても良い。電気二重層キャパシタの電極の極
表面も凹凸を有するが、本発明により電気二重層キャパ
シタの過充電も防止されるからである。A preferred power storage device is a lithium ion secondary battery. This is because, according to the present invention, electrodeposition of lithium ions is prevented, or even when the electrodeposition is performed, the amount is uniform and the amount is small. Further, the power storage device may be an electric double layer capacitor. The reason is that the electrode of the electric double layer capacitor also has uneven surfaces, but the present invention also prevents overcharging of the electric double layer capacitor.
【００１１】[0011]
−実施例１− これは、本発明をリチウムイオン二次電池に適用した実
施例である。この電池は、正極板、負極板及びセパレー
タからなる電極群が非水系の電解液とともに電池ケース
に収納された角形リチウムイオン二次電池である。-Example 1-This is an example in which the present invention is applied to a lithium ion secondary battery. This battery is a prismatic lithium ion secondary battery in which an electrode group including a positive electrode plate, a negative electrode plate, and a separator is housed in a battery case together with a nonaqueous electrolyte.
【００１２】正極板は、厚さ２０μｍ、幅２９ｍｍのＡ
ｌ箔からなる集電体に活物質としてのリチウムコバルト
複合酸化物を含む合剤層が保持されたものである。正極
合剤は、結着剤であるポリフッ化ビニリデン８部と導電
剤であるアセチレンブラック５部とを活物質８７部とと
もに混合してペースト状に調製された。その合剤を、そ
の集電体材料の両面に塗布、乾燥し、加圧することによ
って正極板が製作された。The positive electrode plate has a thickness of 20 μm and a width of 29 mm.
A mixture layer containing a lithium-cobalt composite oxide as an active material is held on a current collector made of a 1-foil. The positive electrode mixture was prepared in the form of a paste by mixing 8 parts of polyvinylidene fluoride as a binder and 5 parts of acetylene black as a conductive agent together with 87 parts of an active material. The mixture was applied to both sides of the current collector material, dried, and pressed to produce a positive electrode plate.
【００１３】負極板は、厚さ１４μｍ、幅３１ｍｍのＣ
ｕ箔からなる集電体にホスト物質としての黒鉛を含む合
剤層が保持されたものである。負極合剤は、黒鉛粉末８
６部と結着剤としてのポリフッ化ビニリデン１４部とを
混合してペースト状に調製された。その合剤を、その集
電体材料の両面に塗布、乾燥し、加圧することによって
負極板が製作された。The negative electrode plate has a thickness of 14 μm and a width of 31 mm.
A current collector made of a u-foil holds a mixture layer containing graphite as a host material. The negative electrode mixture is graphite powder 8
6 parts and 14 parts of polyvinylidene fluoride as a binder were mixed to prepare a paste. The mixture was applied to both sides of the current collector material, dried, and pressed to produce a negative electrode plate.
【００１４】セパレータは、ポリイミド微多孔膜であ
る。これは、分子量約８０００のポリイミド粉末をＮ−
メチルピロリドン（ＮＭＰ）中に溶解しペースト状に調
整し、これを離型紙に展開した後、水中に浸けてＮＭＰ
を除去し乾燥し離型紙を剥離することによって製作され
た。得られたセパレータの断面を走査型電子顕微鏡で観
察したところ、離型紙側の表面のほうが、その反対側の
表面よりも気孔率が４０％小さかった。The separator is a microporous polyimide membrane. This means that N-polyimide powder having a molecular weight of about 8000
Dissolve in methylpyrrolidone (NMP) to prepare a paste, spread it on release paper, immerse it in water
And dried and peeled off the release paper. When the cross section of the obtained separator was observed with a scanning electron microscope, the surface on the release paper side had a porosity 40% smaller than the surface on the opposite side.
【００１５】各々の寸法は、正極板が厚さ１８０μｍ、
幅２９ｍｍで、セパレータ５が厚さ２５μｍ、幅３３ｍ
ｍで、負極板が厚さ２２０μｍ、幅３１ｍｍとなってお
り、セパレータの気孔率の少ない方が負極板と対向する
ように順に重ね合わせてポリエチレンの巻芯を中心とし
て、その周囲に長円渦状に巻いた後、負極端子を兼ねる
電池ケースに収納し、電解液を注入した。電解液は、Ｌ
ｉＰＦ6を１ｍｏｌ／ｌ含むエチレンカーボネート：ジ
エチルカーボネート＝１：１（体積比）の混合液であ
る。Each of the dimensions is such that the positive electrode plate has a thickness of 180 μm,
29 mm wide, separator 5 is 25 μm thick and 33 m wide
m, the negative electrode plate has a thickness of 220 μm and a width of 31 mm, and the separator having the smaller porosity is superimposed in order so as to face the negative electrode plate. After that, the battery was housed in a battery case also serving as a negative electrode terminal, and an electrolyte was injected. The electrolyte is L
iPF6 to 1 mol / l comprising ethylene carbonate: a mixture of 1 (volume ratio): diethyl carbonate = 1.
【００１６】この電池を負極の理論容量の８８％まで充
電した後、６００ｍＡ、４．１Ｖの定電流定電圧で１．
５時間充電し、６００ｍＡの定電流で２．７５Ｖまで放
電するサイクルを繰り返したところ、５００サイクル経
っても初期の放電容量に対して８０％の放電容量を維持
することができた。After charging the battery to 88% of the theoretical capacity of the negative electrode, the battery was charged at a constant current and voltage of 600 mA and 4.1 V for 1.
When a cycle of charging for 5 hours and discharging to 2.75 V at a constant current of 600 mA was repeated, 80% of the initial discharge capacity was maintained even after 500 cycles.
【００１７】−比較例− セパレータとして市販のポリエチレン微多孔膜を使用し
た以外は実施例１と同一条件で電池を製造し、充放電サ
イクルを実施したところ、１００サイクルの時点で放電
容量が初期の５０％に低下した。Comparative Example A battery was manufactured under the same conditions as in Example 1 except that a commercially available microporous polyethylene membrane was used as a separator, and a charge / discharge cycle was carried out. It has dropped to 50%.
【００１８】−実施例２− これは、セパレータに代えてポリマー固体電解質を使用
したリチウムイオン二次電池の例である。本例では電解
質は、ポリフッ化ビニリデンからなる多孔質の固体電解
質膜である。これは、ポリフッ化ビニリデンをＮ−メチ
ルピロリドン（ＮＭＰ）中に溶解しペースト状に調整
し、これを離型紙に展開した後、水中に浸けてＮＭＰを
除去し乾燥し離型紙を剥離することによって製作され
た。得られた固体電解質の断面を走査型電子顕微鏡で観
察したところ、離型紙側の表面のほうが、その反対側の
表面よりも気孔率が５５％小さかった。Example 2 This is an example of a lithium ion secondary battery using a polymer solid electrolyte instead of a separator. In this example, the electrolyte is a porous solid electrolyte membrane made of polyvinylidene fluoride. This is accomplished by dissolving polyvinylidene fluoride in N-methylpyrrolidone (NMP), adjusting it into a paste, spreading it on release paper, immersing it in water to remove NMP, drying and releasing the release paper. Was made. When the cross section of the obtained solid electrolyte was observed with a scanning electron microscope, the surface on the release paper side had a porosity 55% smaller than the surface on the opposite side.
【００１９】セパレータに代えてこの固体電解質を用い
る以外は実施例１と同一条件で電池を製造し、充放電サ
イクルを実施したところ、５００サイクル経っても初期
の８２％の放電容量を維持することができた。A battery was manufactured under the same conditions as in Example 1 except that this solid electrolyte was used in place of the separator, and a charge / discharge cycle was carried out. As a result, the initial discharge capacity was maintained at 82% even after 500 cycles. Was completed.
【００２０】[0020]
【発明の効果】以上のように、本発明によれば、蓄電装
置を高容量で安全なものとすることができるので、携帯
用電子機器の部品として有益である。As described above, according to the present invention, the power storage device can be made high-capacity and safe, which is useful as a component of a portable electronic device.
【図１】 本発明の作用を説明するためのセパレータと
負極の厚さ方向断面図である。FIG. 1 is a cross-sectional view in the thickness direction of a separator and a negative electrode for explaining the operation of the present invention.
１ 負極 ２ セパレータ ３ 気孔 Reference Signs List 1 negative electrode 2 separator 3 pore
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9090280AJPH10270004A (en) | 1997-03-24 | 1997-03-24 | Storage battery |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9090280AJPH10270004A (en) | 1997-03-24 | 1997-03-24 | Storage battery |
| Publication Number | Publication Date |
|---|---|
| JPH10270004Atrue JPH10270004A (en) | 1998-10-09 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9090280APendingJPH10270004A (en) | 1997-03-24 | 1997-03-24 | Storage battery |
| Country | Link |
|---|---|
| JP (1) | JPH10270004A (en) |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001102089A (en)* | 1999-09-29 | 2001-04-13 | Tdk Corp | Solid electrolyte, electrolyte chemical device, lithium secondary cell and electricity double-layer capacitor |
| WO2002027855A1 (en)* | 2000-09-29 | 2002-04-04 | Sharp Corporation | Lithium polymer secondary battery |
| WO2002027858A1 (en)* | 2000-09-29 | 2002-04-04 | Dai-Ichi Kogyo Seiyaku Co., Ltd. | Lithium secondary cell |
| JP2002187925A (en)* | 2000-09-29 | 2002-07-05 | Samsung Sdi Co Ltd | Polymer electrolyte and lithium battery using the same |
| JP2024535838A (en)* | 2022-02-21 | 2024-10-02 | エルジー エナジー ソリューション リミテッド | Separator for lithium-sulfur battery and lithium-sulfur battery including same |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001102089A (en)* | 1999-09-29 | 2001-04-13 | Tdk Corp | Solid electrolyte, electrolyte chemical device, lithium secondary cell and electricity double-layer capacitor |
| WO2002027855A1 (en)* | 2000-09-29 | 2002-04-04 | Sharp Corporation | Lithium polymer secondary battery |
| WO2002027858A1 (en)* | 2000-09-29 | 2002-04-04 | Dai-Ichi Kogyo Seiyaku Co., Ltd. | Lithium secondary cell |
| JP2002187925A (en)* | 2000-09-29 | 2002-07-05 | Samsung Sdi Co Ltd | Polymer electrolyte and lithium battery using the same |
| US7192675B2 (en) | 2000-09-29 | 2007-03-20 | Sharp Kabushiki Kaisha | Lithium polymer secondary battery |
| JP2024535838A (en)* | 2022-02-21 | 2024-10-02 | エルジー エナジー ソリューション リミテッド | Separator for lithium-sulfur battery and lithium-sulfur battery including same |
| Publication | Publication Date | Title |
|---|---|---|
| US5597659A (en) | Manufacturing method of a separator for a lithium secondary battery and an organic electrolyte lithium secondary battery using the same separator | |
| JP4570271B2 (en) | High energy rechargeable lithium battery separator | |
| JP4777593B2 (en) | Method for producing lithium ion secondary battery | |
| CN1284261C (en) | Nonaqueous electrolyte secondary battery and its manufacture | |
| US20140272526A1 (en) | Porous separator for a lithium ion battery and a method of making the same | |
| US5368958A (en) | Lithium anode with conductive for and anode tab for rechargeable lithium battery | |
| JPH09213338A (en) | Battery and lithium-ion secondary battery | |
| JP4088755B2 (en) | Nonaqueous electrolyte secondary battery | |
| US20160211523A1 (en) | Electrode for lithium ion secondary cells, and lithium ion secondary cell | |
| JP2003308877A (en) | Method for producing polymer secondary battery | |
| JP2000077061A (en) | Lithium ion battery | |
| KR100306870B1 (en) | Polymer electrolyte and lithium-polymer battery using the same | |
| JP2005129446A (en) | Electrochemical energy storage device | |
| JPH11120993A (en) | Nonaqueous electrolyte secondary battery | |
| JPH10270004A (en) | Storage battery | |
| JP4664455B2 (en) | Non-aqueous electrolyte secondary battery | |
| JP2001035471A (en) | Non-aqueous electrolyte secondary battery | |
| JPH10261437A (en) | Polymer electrolyte and lithium polymer battery using the same | |
| JPH11195410A (en) | Lithium secondary battery | |
| JPH10106545A (en) | Organic electrolyte secondary battery and manufacture of electrode thereof | |
| JPH05190208A (en) | Lithium secondary battery | |
| JPH11135107A (en) | Lithium secondary battery | |
| JP2002198088A (en) | Lithium secondary cell | |
| JP2000306607A (en) | Nonaqueous electrolyte battery | |
| JPH10270005A (en) | Storage battery |