JP4436464B2

JP4436464B2 - Lithium ion battery

Info

Publication number: JP4436464B2
Application number: JP23403897A
Authority: JP
Inventors: 束伊藤; 訓生川
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1997-08-29
Filing date: 1997-08-29
Publication date: 2010-03-24
Anticipated expiration: 2017-08-29
Also published as: JPH1173973A

Description

【０００１】
【発明の属する技術分野】
本発明は、リチウムを挿入，離脱可能な材料から成る正極活物質及びこの正極活物質を保持する帯状の正極集電体を含む正極と、リチウムを挿入，離脱可能な材料から成る負極活物質及びこの負極活物質を保持する帯状の負極集電体を含む負極とが、セパレータを介して配置される構造のリチウムイオン電池に関する。
【０００２】
【従来の技術】
従来より、アルカリ蓄電池用の電極に係る分野においては、特開昭６２−１３３６７０号公報に示されるように、発泡金属板（集電部材）の多孔部に電極を構成する活物質のほぼ全部を含有させることにより、活物質と発泡金属板との密着強度を高めると共に、電極の内部抵抗を低減するような技術が提案されている。
また、上記公報においては、集電タブと電極本体部との界面において、機械的な破断が生じるのを抑制すべく、スポンジ状金属多孔体のリード溶着部の隣にテーパ部分を有する活物質充填部を設けるような構造のものが提案されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、このような技術を、アルカリ電池用電極に用いられるような比較的厚みが大きいスポンジニッケル多孔体に適用する場合には所定の効果を有するものの、リチウムイオン電池用電極に用いられるような厚みが小さいフレキシブル銅スポンジなどに適用した場合には、テーパ部端部とリード溶着部との界面において破断応力に対する強度低下を招くため、充分に強度を向上させることができないという課題がある。
【０００４】
本発明は、上記従来の課題を考慮してなされたものであって、厚みが小さな電極の集電部材に金属多孔体を用いた場合であっても、充分な強度を備えるリチウムイオン電池を提供することを目的としている。
【０００５】
【課題を解決するための手段】
上記目的を達成するために、本発明のリチウムイオン電池は、リチウムを挿入，離脱可能な材料から成る正極活物質及びこの正極活物質を保持する帯状の正極集電体を含む正極と、リチウムを挿入，離脱可能な材料から成る負極活物質及びこの負極活物質を保持する帯状の負極集電体を含む負極とが、セパレータを介して配置されると共に、上記正極集電体及び／又は上記負極集電体が三次元網目構造を有する金属多孔体から成るリチウムイオン電池であって、上記金属多孔体は、活物質を保持するための本体部と、
上記金属多孔体を構成する金属を追加メッキしてなる部分であって、上記金属多孔体の幅方向端部に設けられた電流導出端子部と、を有し、上記本体部の一部には更に、上記追加メッキ金属により上記電流導出端子部と一体的に形成された集電部が設けられ、上記集電部は、上記電流導出端子部に対して垂直方向に延設され、
上記電流導出端子部と集電部とにおける金属の目付が、上記集電部を除く本体部の金属の目付より大きくなるように構成されていることを特徴とする。
【０００６】
上記構成の如く、活物質を保持するための本体部と電流導出端子部とが一体的に形成されていれば、金属多孔体（発泡金属基体）の端部を単に圧延することにより電流導出端子部（集電端子部）を形成する場合に比べて、本体部と集電端子部との間における強度が大きくなるので、この部分での破損率を小さくすることができる。
【０００７】
また、集電効果の高い３次元網目構造を有する金属多孔体を正、負極活物質の保持体兼集電部材として用いているので、正、負極活物質と集電部材との密着強度を高めることができるとともに、電池の内部抵抗を低減することができる。特に、当該技術を負極に適用した場合には、極板から脱落し易い黒鉛等の負極活物質の結着性を向上させることができるという効果も発揮しうる。
加えて、本体部の一部には当該本体部の金属の目付より大なる集電部が設けられているので、電池の内部抵抗が更に低減し、この結果高率放電特性を飛躍的に向上させることができる。
【０００８】
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、本体部の面積に対する集電部の面積の割合が５〜１５％であることを特徴とする。
集電部の面積の割合を上記範囲内に規制するのは、以下に示す理由による。
即ち、集電部の面積の割合が１５％を超えると、活物質の充填量が減少する結果、電池容量の低下を招く一方、集電部の面積の割合が５％未満になると、電池の内部抵抗が増大するために高率放電特性が低下するからである。
【０００９】
【発明の実施の形態】
本発明の実施の形態を、図１及び図２に基づいて、以下に説明する。
（負極の作製）
ウレタンフォームを出発原料とし、このウレタンフォームに銅の無電解メッキを施し、更に銅の電解メッキを施した後、ウレタン樹脂を酸化脱煤除去し、更に銅スポンジ体を還元アニール処理することにより、Ａ４サイズの電池に対応する銅の発泡体（多孔度９７％、厚み０．５ｍｍ、目付１５０ｇ／ｍ²）を得た。次いで、上記銅の発泡体の片面に特定パターン（図１の斜線部が開口しているようなパターン）の樹脂製遮蔽板を介在させた状態で、追加の銅の電解メッキを行って負極集電体用の銅スポンジ部材を作製した。尚、上記追加の銅の電解メッキにより、樹脂製遮蔽板の開口部に対応する銅の発泡体の部分においては、更に銅メッキがされることとなり、当該部分においては多孔度が約７８％で、目付が約２２５ｇ／ｍ²となった。
【００１０】
ここで、図１に示すように、上記工程により得られた負極集電体（銅スポンジ部材）１の具体的な構造は、多孔度が９７％、目付が１５０ｇ／ｍ²の本体部４と、多孔度が約７８％、目付が約２２５ｇ／ｍ²で且つ銅の発泡体の長手方向に延設される電流導出端子部２とが一体形成されると共に、上記本体部４の一部には、多孔度が約７８％、目付が約２２５ｇ／ｍ²で且つ上記電流導出端子部２に対して略垂直方向に延設されると共に上記電流導出端子部２と接続された集電部３…が形成される構造である。尚、上記本体部４の面積に対する上記集電部３…の面積の割合は５％となるように構成されている。
【００１１】
次に、粒子径５〜２５μｍの天然黒鉛粉末９５重量部と、ポリフッ化ビニリデンを固形分として５重量部だけ溶解させたＮ−メチル−２−ピロリドン溶液とを混合して負極活物質スラリーを作製した。
次いで、前記銅スポンジ部材を平坦なガラス板上に載置した後、銅スポンジ部材の中央部に上方から上記負極活物質スラリーを所定量だけ徐々に滴下しながら、へらで負極活物質スラリーを銅スポンジ部材の内部に擦り込むようにして、全面均等に負極活物質スラリーを充填した。その後、乾燥，圧延処理した後、所定寸法に切断することにより、負極を作製した。
【００１２】
（正極の作製）
ＬｉＣｏＯ₂を８５重量部と、人造黒鉛粉末を５重量部と、カーボンブラック５重量部とを充分に混合した後、この混合物とポリフッ化ビニリデンを固形分として５重量部だけ溶解させたＮ−メチル−２−ピロリドン溶液とを混合することにより正極活物質スラリーを作製した。次に、この正極活物質スラリーを、厚み２０μｍのアルミニウム箔から成る集電体の両面に塗布した後、乾燥，圧延処理し、更に所定寸法に切断することにより、正極を作製した。
【００１３】
（電池の作製）
上記正、負極板の間に、セパレータである微多孔膜（旭化成のハイポア微多孔膜であって、空孔率が８０％、厚みが３０μｍ）を狭着した後、これらを円筒状に巻き取って電極体を作製し、更にこの電極体をプレスすることにより長円形状に成形した。次に、この電極体をアルミニウム製の角形電池用の外装缶に挿入した後、エチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）の等容積混合溶媒に１．０モル／リットルの割合でＬｉＣｌＯ₄を溶解させた電解液を所定量注液し、更に負極端子付き電池封口蓋で封口した。この際、正極の端部には、活物質を除去された芯体露出部が形成されており、この芯体露出部と上記外装缶とにはアルミニウム製のリード板がそれぞれ電気溶接法にて溶着され、これにより正極と外装缶とが電気的に接続される。一方、負極の電流導出端子部と電池封口蓋に形設された負極端子とには銅製のリード板がそれぞれ電気溶接法にて溶着され、これにより負極と負極端子とが電気的に接続される。これらの製造工程を経て、タイプ８１２２４８（厚み８．１ｍｍ、幅２２．５ｍｍ、高さ４８ｍｍ）で、電圧３．６Ｖ、公称容量５５０ｍＡｈのリチウムイオン電池が作製される。
【００１４】
ここで、上記発明の実施の形態では、イオン電池について説明したが、本発明はこれに限定するものではなく、ゲル状の電解質を用いたゲル化電池にも適用しうることは勿論である。
また、本発明は負極に適用される場合に限定するものではなく、正極にも適用しうる。
【００１５】
更に、上記発明の実施の形態では、電流導出端子部２と集電部３…とは、銅の発泡体の片面に特定パターンを有する遮蔽板を介在させた状態で、追加の銅の電解メッキを行うことによって形成されたが、このような方法に限定するものではなく、例えば、電流導出端子部２及び集電部３…に対応する対極（アノード）と電流導出端子部２等との距離を、本体部４に対応する対極と本体部４との距離より短くして電解メッキするような方法であっても良い。このような方法で電解メッキすれば、メッキ処理が１回で済むという利点がある。また、メッキ方法としては、電解メッキ法に限定するものではなく、無電解メッキ法を用いることも可能である。
加えて、集電部３…の形状としては、図１に示すような形状に限定するものではなく、例えば図２に示すような先細り形状であっても良い。
【００１６】
【実施例】
〔実施例１〕
実施例１としては、上記発明の実施の形態に示したリチウムイオン電池を用いた。
このような構造の電池を、以下本発明電池Ａ１と称する。
【００１７】
〔実施例２〕
本体部の面積に対する集電部の面積の割合（以下、集電部の面積の割合と略す）が１０％となるように構成する他は、上記実施例１と同様にして電池を作製した。
このような構造の電池を、以下本発明電池Ａ２と称する。
【００１８】
〔実施例３〕
電解質として、下記の製造方法にて作製されるゲル状電解質を用いる他は、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、本発明電池Ａ３と称する。
尚、電解質の作製は、上記実施例１のイオン電池の組み立て手順において、上記電解液に代えて、熱重合開始剤としてのパーロイルＴＣＰ〔化学式（ｔＢｕ−Ｈｅ−ＯＣＯＯ）₂で表される。尚、Ｈｅはシクロヘキシルである。〕を５００ＰＰＭ添加したモノマー組成物〔ＰＥＧウレタンアクリレート系プレポリマーと、ＥＣとＤＥＣとの等容積混合溶媒に１．０モル／リットルの割合でＬｉＣｌＯ₄を溶解させた電解液との重量比が１：６の組成物〕を外装缶内に注液した後、電池の封口を行い、更に封口完了後電池を、恒温槽（７５℃）に３０分間投入することにより、電解液をポリマーゲル化した。
【００１９】
〔実施例４〕
集電部の面積の割合が１０％となるように構成する他は、上記実施例３と同様にして電池を作製した。
このような構造の電池を、以下本発明電池Ａ４と称する。
【００２０】
〔比較例１〕
集電部の面積の割合が０％となる構成（即ち、集電部が形成されていない構成）とする他は、上記実施例１と同様にして電池を作製した。尚、比較例１の電池の負極を作製する際に用いられる追加メッキ用の遮蔽板は、電流導出端子部に対応する部位のみ矩形状に開口しているものを用いた。
このような構造の電池を、以下比較電池Ｘ１と称する。
【００２１】
〔比較例２〕
集電部の面積の割合が０％となる構成（即ち、集電部が形成されていない構成）とする他は、上記実施例３と同様にして電池を作製した。
このような構造の電池を、以下比較電池Ｘ２と称する。
【００２２】
〔実験１〕
上記本発明電池Ａ１〜Ａ４と比較電池Ｘ１、Ｘ２とにおいて、下記の条件で充放電を行い、電流値が０．２Ｃでの電池容量と、電流値が２Ｃでの電池容量と、電流値が０．２Ｃでの電池容量に対する電流値が２Ｃでの電池容量の比率を求めたので、それらの結果を下記表１に示す。
【００２３】
・充放電条件

尚、１サイクル目と２サイクル目との充放電は、電池の活性化のための充放電であり、また、３サイクル目の放電時における電池容量を電流値が０．２Ｃでの電池容量とし、４サイクル目の放電時における電池容量を電流値が２Ｃでの電池容量とした。
【００２４】
【表１】

【００２５】
上記表１から明らかなように、本発明電池Ａ１、Ａ２は比較電池Ｘ１に比べてまた、本発明電池Ａ３、Ａ４は比較電池Ｘ２に比べて、それぞれ高率放電特性に優れていることが認められ、特に、ゲル化電池の場合に（本発明電池Ａ３、Ａ４と比較電池Ｘ２との対比において）、高率放電特性が飛躍的に向上するることが認められる。
したがって、高率放電特性の向上という観点からは、集電部の面積の割合は５％以上であることが望ましい。
【００２６】
〔実験２〕
集電部の面積の割合を変化させて、各割合における充填可能な活物質量について調べたので、その結果を下記表２に示す。尚、表２においては、集電部の面積の割合が０％となる場合（即ち、集電部が形成されていない場合）の充填可能な活物質量を１００として表している。
【００２７】
【表２】

【００２８】
表２から明らかなように、集電部の面積の割合が１５％を超えると、充填可能な活物質量が極めて減少していることが認められる。
したがって、充填可能な活物質量の増大という観点からは、集電部の面積の割合は１５％以下であることが望ましい。
上記実験１及び実験２より、高率放電特性の向上を図りつつ、充填可能な活物質量の増大を図るには、集電部の面積の割合が５〜１５％であるのが望ましい。
【００２９】
【発明の効果】
以上で説明したように本発明によれば、本体部と集電端子部との間における強度が高くなるので、この部分での破損率を小さくすることができ、且つ正、負極活物質と集電部材との密着強度を高めることができると共に、電池の内部抵抗を低減して、高率放電特性を飛躍的に向上させることができるといった優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明に用いられる金属多孔体の一例を示す正面図である。
【図２】本発明に用いられる金属多孔体の他の例を示す正面図である。
【符号の説明】
１：負極
２：電流導出端子部
３：集電部
４：本体部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positive electrode active material made of a material capable of inserting and removing lithium, a positive electrode including a strip-shaped positive electrode current collector holding the positive electrode active material, a negative electrode active material made of a material capable of inserting and removing lithium, and The present invention relates to a lithium ion battery having a structure in which a negative electrode including a strip-shaped negative electrode current collector holding the negative electrode active material is disposed via a separator.
[0002]
[Prior art]
Conventionally, in the field related to electrodes for alkaline storage batteries, as disclosed in Japanese Patent Application Laid-Open No. 62-133670, almost all of the active material constituting the electrodes is formed in the porous portion of the metal foam plate (current collecting member). There has been proposed a technique for increasing the adhesion strength between the active material and the metal foam plate and reducing the internal resistance of the electrode.
Further, in the above publication, in order to suppress mechanical breakage at the interface between the current collecting tab and the electrode main body portion, the active material filling having a tapered portion adjacent to the lead welded portion of the sponge metal porous body is provided. The thing of the structure which provides a part is proposed.
[0003]
[Problems to be solved by the invention]
However, when such a technique is applied to a sponge nickel porous body having a relatively large thickness as used in an alkaline battery electrode, it has a predetermined effect, but has a thickness as used in a lithium ion battery electrode. When applied to a flexible copper sponge or the like having a small thickness, there is a problem that the strength cannot be sufficiently improved because the strength against the breaking stress is reduced at the interface between the end of the tapered portion and the lead welded portion.
[0004]
The present invention has been made in consideration of the above-described conventional problems, and provides a lithium ion battery having sufficient strength even when a metal porous body is used as a current collecting member for an electrode having a small thickness. The purpose is to do.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a lithium ion battery of the present invention comprises a positive electrode active material made of a material into which lithium can be inserted and removed, a positive electrode including a strip-shaped positive electrode current collector holding the positive electrode active material, and lithium. A negative electrode active material composed of a material that can be inserted and removed, and a negative electrode including a strip-shaped negative electrode current collector that holds the negative electrode active material are disposed via a separator, and the positive electrode current collector and / or the negative electrode The current collector is a lithium ion battery comprising a porous metal body having a three-dimensional network structure, the porous metal body having a main body for holding an active material,
A portion formed by additionally plating the metal constituting the metal porous body, the current lead-out terminal portion provided at the end in the width direction of the metal porous body, and a part of the main body portion Furthermore, a current collecting part formed integrally with the current deriving terminal part by the additional plating metal is provided, and the current collecting part extends in a direction perpendicular to the current deriving terminal part,
The metal basis weight of the current lead-out terminal portion and the current collector portion is configured to be larger than the metal basis weight of the main body portion excluding the current collector portion.
[0006]
If the main body for holding the active material and the current deriving terminal are integrally formed as in the above configuration, the current deriving terminal is simply rolled by rolling the end of the metal porous body (foamed metal substrate). Since the strength between the main body portion and the current collecting terminal portion is increased as compared with the case where the portion (current collecting terminal portion) is formed, the breakage rate at this portion can be reduced.
[0007]
In addition, since a porous metal body having a three-dimensional network structure having a high current collecting effect is used as a positive and negative electrode active material holder and a current collecting member, the adhesion strength between the positive and negative electrode active materials and the current collecting member is increased. And the internal resistance of the battery can be reduced. In particular, when the technology is applied to a negative electrode, the effect of improving the binding property of a negative electrode active material such as graphite that easily falls off from the electrode plate can be exhibited.
In addition, a part of the main body is provided with a current collector that is larger than the metal weight of the main body, so that the internal resistance of the battery is further reduced, resulting in a dramatic improvement in high-rate discharge characteristics. Can be made.
[0008]
The invention according to claim 2 is characterized in that, in the invention according to claim 1, the ratio of the area of the current collector to the area of the main body is 5 to 15%.
The reason why the area ratio of the current collector is regulated within the above range is as follows.
That is, if the area ratio of the current collector exceeds 15%, the amount of the active material is reduced, resulting in a decrease in battery capacity. On the other hand, if the area ratio of the current collector is less than 5%, This is because high-rate discharge characteristics deteriorate due to an increase in internal resistance.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.
(Preparation of negative electrode)
Using urethane foam as a starting material, after applying electroless plating of copper to this urethane foam, and further applying electrolytic plating of copper, the urethane resin is oxidized and degreased and removed, and the copper sponge body is further subjected to reduction annealing treatment, A copper foam (porosity 97%, thickness 0.5 mm, basis weight 150 g / m ² ) corresponding to an A4 size battery was obtained. Then, with a resin shielding plate having a specific pattern (a pattern in which the hatched portion in FIG. 1 is opened) interposed on one side of the copper foam, additional copper electrolytic plating is performed to perform negative electrode collection. A copper sponge member for an electric body was produced. By the additional copper electroplating, the copper foam portion corresponding to the opening of the resin shielding plate is further plated with copper, and the porosity is about 78% in that portion. The basis weight was about 225 g / m ² .
[0010]
Here, as shown in FIG. 1, the specific structure of the negative electrode current collector (copper sponge member) 1 obtained by the above-described process is as follows: the main body 4 having a porosity of 97% and a basis weight of 150 g / m ² ; The current lead-out terminal portion 2 having a porosity of about 78%, a basis weight of about 225 g / m ² and extending in the longitudinal direction of the copper foam is integrally formed, and part of the main body portion 4 Has a porosity of about 78%, a basis weight of about 225 g / m ² , and extends in a direction substantially perpendicular to the current deriving terminal portion 2 and connected to the current deriving terminal portion 2. Is a structure in which ... is formed. In addition, the ratio of the area of the said current collection part 3 ... with respect to the area of the said main-body part 4 is comprised so that it may be 5%.
[0011]
Next, 95 parts by weight of natural graphite powder having a particle size of 5 to 25 μm and an N-methyl-2-pyrrolidone solution in which only 5 parts by weight of polyvinylidene fluoride is dissolved as a solid content are mixed to prepare a negative electrode active material slurry. did.
Next, after placing the copper sponge member on a flat glass plate, the negative electrode active material slurry is copper-coated with a spatula while gradually dropping a predetermined amount of the negative electrode active material slurry from above onto the center of the copper sponge member. The negative electrode active material slurry was filled evenly over the entire surface so as to rub into the sponge member. Then, after drying and rolling, the negative electrode was produced by cutting to a predetermined size.
[0012]
(Preparation of positive electrode)
After thoroughly mixing 85 parts by weight of LiCoO ₂ , 5 parts by weight of artificial graphite powder, and 5 parts by weight of carbon black, N-methyl in which only 5 parts by weight of this mixture and polyvinylidene fluoride were dissolved as a solid content was dissolved. A positive electrode active material slurry was prepared by mixing the -2-pyrrolidone solution. Next, this positive electrode active material slurry was applied to both sides of a current collector made of an aluminum foil having a thickness of 20 μm, then dried and rolled, and further cut into predetermined dimensions to produce a positive electrode.
[0013]
(Production of battery)
Between the positive and negative plates, a microporous membrane as a separator (Asahi Kasei's hypoporous microporous membrane having a porosity of 80% and a thickness of 30 μm) is tightly wound, and these are wound into a cylindrical shape to form an electrode. A body was prepared, and the electrode body was further pressed into an oval shape. Next, after inserting this electrode body into an aluminum can outer battery can, LiClO ₄ was added to an equal volume mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) at a rate of 1.0 mol / liter. A predetermined amount of the dissolved electrolyte solution was poured, and further sealed with a battery sealing lid with a negative electrode terminal. At this time, a core exposed portion from which the active material has been removed is formed at the end of the positive electrode, and an aluminum lead plate is formed on each of the core exposed portion and the outer can by an electric welding method. By welding, the positive electrode and the outer can are electrically connected. On the other hand, a copper lead plate is welded to the negative electrode current lead-out terminal portion and the negative electrode terminal formed on the battery sealing lid by an electric welding method, whereby the negative electrode and the negative electrode terminal are electrically connected. . Through these manufacturing steps, a lithium ion battery of type 81248 (thickness 8.1 mm, width 22.5 mm, height 48 mm), voltage 3.6 V, and nominal capacity 550 mAh is manufactured.
[0014]
Here, in the embodiment of the present invention, the ion battery has been described. However, the present invention is not limited to this, and can be applied to a gelled battery using a gel electrolyte.
Moreover, this invention is not limited to the case where it applies to a negative electrode, It can apply also to a positive electrode.
[0015]
Furthermore, in the embodiment of the present invention, the current deriving terminal portion 2 and the current collecting portions 3... Are added with electrolytic plating of additional copper with a shielding plate having a specific pattern interposed on one side of the copper foam. However, the present invention is not limited to such a method. For example, the distance between the counter electrode (anode) corresponding to the current deriving terminal portion 2 and the current collecting portions 3. Alternatively, a method may be employed in which electrolytic plating is performed by making the distance shorter than the distance between the counter electrode corresponding to the main body 4 and the main body 4. If electrolytic plating is performed by such a method, there is an advantage that only one plating process is required. The plating method is not limited to the electrolytic plating method, and an electroless plating method can also be used.
In addition, the shape of the current collectors 3 is not limited to the shape as shown in FIG. 1, and may be a tapered shape as shown in FIG. 2, for example.
[0016]
【Example】
[Example 1]
As Example 1, the lithium ion battery described in the embodiment of the invention was used.
The battery having such a structure is hereinafter referred to as the present invention battery A1.
[0017]
[Example 2]
A battery was fabricated in the same manner as in Example 1 except that the ratio of the area of the current collector to the area of the main body (hereinafter abbreviated as the ratio of the area of the current collector) was 10%.
The battery having such a structure is hereinafter referred to as the present invention battery A2.
[0018]
Example 3
A battery was produced in the same manner as in Example 1 except that a gel electrolyte produced by the following production method was used as the electrolyte.
The battery thus produced is hereinafter referred to as the present invention battery A3.
In addition, in the assembly procedure of the ion battery of Example 1, the production of the electrolyte is represented by perloyl TCP [chemical formula (tBu-He-OCOO) ₂ as a thermal polymerization initiator instead of the electrolytic solution. He is cyclohexyl. The weight ratio of the PEG urethane acrylate prepolymer and the electrolyte solution in which LiClO ₄ is dissolved in an equal volume mixed solvent of EC and DEC at a rate of 1.0 mol / liter is 1 : 6 composition] was poured into the outer can, the battery was sealed, and after the sealing was completed, the battery was charged into a thermostat (75 ° C.) for 30 minutes to polymerize the electrolyte. .
[0019]
Example 4
A battery was fabricated in the same manner as in Example 3 except that the area ratio of the current collector was 10%.
The battery having such a structure is hereinafter referred to as “invention battery A4”.
[0020]
[Comparative Example 1]
A battery was fabricated in the same manner as in Example 1 above, except that the area ratio of the current collector was 0% (that is, the structure in which the current collector was not formed). In addition, the shielding plate for additional plating used when producing the negative electrode of the battery of Comparative Example 1 was a plate that opened in a rectangular shape only at a portion corresponding to the current lead-out terminal portion.
The battery having such a structure is hereinafter referred to as a comparative battery X1.
[0021]
[Comparative Example 2]
A battery was fabricated in the same manner as in Example 3, except that the area ratio of the current collector was 0% (that is, the structure in which the current collector was not formed).
The battery having such a structure is hereinafter referred to as a comparative battery X2.
[0022]
[Experiment 1]
In the present invention batteries A1 to A4 and the comparative batteries X1 and X2, charging and discharging are performed under the following conditions, the battery capacity at a current value of 0.2C, the battery capacity at a current value of 2C, and the current value are Since the ratio of the battery capacity when the current value with respect to the battery capacity at 0.2 C was 2 C was determined, the results are shown in Table 1 below.
[0023]
・ Charging / discharging conditions

The charge / discharge in the first cycle and the second cycle is charge / discharge for activation of the battery, and the battery capacity at the time of discharge in the third cycle is defined as the battery capacity at a current value of 0.2C. The battery capacity at the time of discharging at the fourth cycle was defined as the battery capacity at a current value of 2C.
[0024]
[Table 1]

[0025]
As is clear from Table 1 above, the present invention batteries A1 and A2 are superior to the comparative battery X1, and the present invention batteries A3 and A4 are superior to the comparative battery X2 in terms of high rate discharge characteristics. In particular, in the case of a gelled battery (in comparison with the batteries A3 and A4 of the present invention and the comparative battery X2), it is recognized that the high rate discharge characteristics are dramatically improved.
Therefore, from the viewpoint of improving the high rate discharge characteristics, the area ratio of the current collector is preferably 5% or more.
[0026]
[Experiment 2]
The amount of the active material that can be filled at each ratio was examined by changing the ratio of the area of the current collector, and the results are shown in Table 2 below. In Table 2, the amount of active material that can be filled when the area ratio of the current collector is 0% (that is, when the current collector is not formed) is represented as 100.
[0027]
[Table 2]

[0028]
As is apparent from Table 2, when the ratio of the area of the current collector exceeds 15%, it is recognized that the amount of active material that can be filled is extremely reduced.
Therefore, from the viewpoint of increasing the amount of active material that can be filled, the ratio of the area of the current collector is preferably 15% or less.
From Experiment 1 and Experiment 2, it is desirable that the ratio of the area of the current collector is 5 to 15% in order to increase the amount of active material that can be filled while improving the high rate discharge characteristics.
[0029]
【The invention's effect】
As described above, according to the present invention, since the strength between the main body portion and the current collecting terminal portion is increased, the breakage rate at this portion can be reduced, and the positive and negative electrode active materials and the current collector can be reduced. The adhesive strength with the electric member can be increased, and the excellent effect of reducing the internal resistance of the battery and dramatically improving the high rate discharge characteristics can be achieved.
[Brief description of the drawings]
FIG. 1 is a front view showing an example of a porous metal body used in the present invention.
FIG. 2 is a front view showing another example of a porous metal body used in the present invention.
[Explanation of symbols]
1: Negative electrode 2: Current deriving terminal part 3: Current collecting part 4: Body part

Claims

A positive electrode including a positive electrode active material made of a material capable of inserting and removing lithium, and a strip-shaped positive electrode current collector holding the positive electrode active material;
A negative electrode active material made of a material capable of inserting and removing lithium and a negative electrode including a strip-shaped negative electrode current collector that holds the negative electrode active material are disposed via a separator, and the positive electrode current collector and / or The negative electrode current collector is a lithium ion battery comprising a porous metal body having a three-dimensional network structure,
The metal porous body includes a main body for holding an active material,
A portion formed by additionally plating the metal constituting the metal porous body, and having a current derivation terminal portion provided at an end in the width direction of the metal porous body,
A part of the main body is further provided with a current collector formed integrally with the current lead-out terminal by the additional plating metal,
The current collector extends in a direction perpendicular to the current derivation terminal,
The metal basis weight of the current lead-out terminal part and the current collector part is configured to be larger than the metal basis weight of the main body part excluding the current collector part,
The lithium ion battery characterized by the above-mentioned.

The lithium ion battery according to claim 1, wherein a ratio of the area of the current collector to the area of the main body is 5 to 15%.