JP3750490B2

JP3750490B2 - battery

Info

Publication number: JP3750490B2
Application number: JP2000164582A
Authority: JP
Inventors: 昭白神; 広明漆畑; 久塩田; 淳荒金; 隆西村; 純一細川; 省二吉岡; 万希子吉瀬; 茂相原; 大吾竹村; 宏徳栗木; 将光岡村; 琢也大賀; 修大徳
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2000-06-01
Filing date: 2000-06-01
Publication date: 2006-03-01
Anticipated expiration: 2020-06-01
Also published as: JP2001345115A

Description

【０００１】
【発明の属する技術分野】
この発明は渦巻型構造を持つ電池の構造に関するもので、特に正極もしくは負極を接着する渦巻き型電池の生産性と安全性とエネルギー密度を向上させるものである。
【０００２】
【従来の技術】
近年における携帯用電子機器の小型、薄型化のために、この電子機器の電源として用いる電池、特に繰り返し充電可能な二次電池に対しての小型、薄型化性能向上が求められてきている。電子機器をより長時間駆動する事ができ、軽量で持ち運びが容易でかつ高容量な電池としてリチウムイオン二次電池が注目されている。そこで本発明ではリチウムイオン電池を例として説明する。
【０００３】
負極、セパレータ、正極からなる電極体の構造は、ボビン型、積層型、渦巻き型が知られているが、パソコンや携帯電話等の一般の携帯機器には高パルス放電が必要であり一般的に渦巻き型の電極体構造が用いられる。
【０００４】
渦巻き型構造の電極体は通常円筒型がよく使用されるが、薄型化のためには偏平状に巻き取るか、もしくはプレスして平板化する必要がある。このとき、形状維持のためには、テープ等を巻いて固定し外装缶に封入するか、電極を接着することで電極形状を維持させる必要がある。例えば特開平１０−３０２８４３号公報に後者の構造の例が開示されている。後者は頑丈な外装缶に封入しなくても形状が維持されるというメリットを持つ。また、電極とセパレータを接着することで短絡時の安全性も増すというメリットも持つ。
【０００５】
【発明が解決しようとする課題】
渦巻状電極体を作製する場合には、渦巻状に巻くための巻芯が必要であり、電極の一部分を巻芯に巻きつけたり挟みつけて巻状電極体を作成するが、接着しながら渦巻状に電極を巻くと、電極に塗布された接着剤が巻芯に接着剤が付着してしまうために、巻芯が汚れるだけでなく、巻芯に接着剤が付着して電極に接着剤未塗布部が生じたり、巻芯に付着した接着剤が他の部位に付着してしまうという問題が生じる。また、固まった接着剤が電極体内部に混入することで電極間に内部空間が生じたりセパレータを貫通して電極が短絡する原因となる恐れも考えられる。例えば図９に示すように正極集電端子１と正極活物質層３が近接している場合、接着剤１０は正極集電端子１上にも塗布されてしまう。そのため、接着剤を塗布した正極を巻芯に接触しないように図９のように配置すると負極の余剰分Fが生じる。
【０００６】
この発明は上記の問題を解決するためになされたもので、安全性および生産性が高く、高エネルギー密度が得られる電池を提供することを目的とするものである。
【０００７】
【課題を解決するための手段】
この発明に係わる第１の電池は、絶縁性を有し電解液を保持するセパレータに挟まれた第１の活物質層と第１の集電体とを備えた第１の電極の端部は第１の集電端子に接続され、電解液を保持する接着層に挟まれた第２の活物質層と第２の集電体とを備えた第２の電極の端部は第２の集電端子に接続され、前記第１の電極と前記第２の電極とを巻き込み、前記第１の電極を挟むセパレータと前記第２の電極とを、前記第２の電極を挟む接着層を介して一体化する電池であって、前記第１の電極、あるいは第２の電極を巻き込む中心部には、前記第１の電極の第１の集電端子と、この第１の電極の第１の集電端子に半周遅れた位置に前記第２の電極の第２の集電端子とが配置されており、前記巻き込む中心部の前記第２の電極の端部は前記第２の集電体の露出した部位を有し、この露出した部位が折曲部を構成したものである。
【０００８】
【発明の実施の形態】
実施の形態１．
以下、本発明の実施の形態を図に基づいて説明する。図１は本発明の実施の形態１における電池の正極の展開図、図２は図１のX−X'断面図、図３は正極の展開図であり図１の裏面を示す。図４は電池の負極の展開図、図５は図４のY−Y'断面図、図６は負極の展開図であり図４の裏面を示す。図において、１は正極集電端子、２は正極集電体、３は正極活物質層、４は負極集電端子、５は負極集電体、６は負極活物質層、７は例えば高分子多孔膜よりなるセパレータ、８は保護テープである。また、図１に示す正極において正極が巻芯と接触する部分に接着剤未塗布部分Ａを設ける。図３に示す裏面では直接巻芯とは接触しないので、接着剤未塗布Ｂは設けても設けなくてもよい。図４乃至図６に示す負極における活物質層の未塗工部分Ｃ乃至Ｅは、電極を巻いて渦巻状電極体にした場合に対向する正極活物質が存在しないため設けている。すなわち活物質層の未塗工部分Ｃ、Ｄは巻き芯に面するため、活物質層の未塗工部分Ｅは渦巻状電極体の最外層に当たるため、対向する正極が存在しない。また、この例ではあらかじめ負極の両面にセパレータ７を接着している。
【０００９】
図７、および図８は上記作成した正極と負極を巻き込んで形成した電池の断面図であり、図において、９は巻芯、１０は接着剤、１１は折曲部である。この電池では、まず、対向する１対の巻芯９でセパレータ付き負極の活物質層の未塗工部分Ｃ及びＤを挟んで巻芯９を一回折り曲げる。次に、図７に示すように、接着剤１０を両面の正極活物質層３に塗布した正極を負極間に挿入し巻き込んでいく。このとき巻芯に接触する正極には接着剤未塗布部分ＡおよびＢを設ける。最外層には負極の活物質層の未塗工部分Ｅが配置されている。その後、巻芯９を抜き取りプレスして密着させ、図８に示すような渦巻状電極体が得られる。このように電池を製造することにより、折曲部１１には接着層は形成されない。ただし、図８では接着剤層、セパレータは記載していない。図８の渦巻状電極体は中心部にセパレータ７つきの負極集電体５すなわち負極を連続して２層有し、負極の先端から半周遅れた位置に正極集電体２の先端が位置し、この外周に正極集電体２と負極集電体５すなわち正極と負極がセパレータを介して順次巻き込まれている構造となっている。また、最外層の集電体５の外側には活物質層が形成されていない。
【００１０】
本実施の形態によれば、セパレータ付き負極を巻芯９で挟み一回折り曲げられた後に、捲芯に接触する部分に接着剤１０を塗布していない正極が挿入されて巻き込まれた構造であるので、接着剤１０塗布面が巻芯９に触れず巻芯９に接着剤１０が付着しにくく、巻芯９が汚れて巻芯９に付着した接着剤１０が他の部分に付着したり、電極に接着剤１０の未塗工部が生じたり、固まった接着剤１０が電極体内部に混入して電極間に内部空間が生じたりセパレータ７を貫通して電極が短絡するなどの不都合を防止でき、信頼性の高い電池が生産性良く得られる。また、正極集電端子１を図７の位置に配置する事で正極活物質３と負極活物質６はほぼ同じ対向面積を得ることが出来、活物質の無駄が無い構造となったことでエネルギー密度を向上させることができる。
【００１１】
また、対向する正極が無く電池反応が期待できない電極（本実施の形態では負極）の巻芯９に面する部分Ａ、Ｂや電極（本実施の形態では負極）の最外層の外側は、活物質層を形成しないことで体積エネルギー密度を向上させることができる。
【００１２】
また、正極および負極の少なくとも一方（本実施の形態では負極）にセパレータを予め接着しておくことにより巻き込みの作業性が向上する。
【００１３】
なお、本実施の形態では負極を第１の電極とし、セパレータ７を予め接着し、正極を第２の電極として、２つの電極を巻き込み、中心部の折曲部に接着層を設けない例を示したが、正極を第１の電極、負極を第２の電極としてもよい。
【００１４】
【実施例】
上記のような電池の構造を形成するための具体的な実施例について説明する。
（正極の作製）
ＬｉＣｏ０２からなる正極活物質９１重量部と、導電剤としての人造黒鉛６重量部と、結着剤としてのポリフッ化ビニリデン（以下、ＰＶｄＦと略す）３重量部をＮ−メチルピロリドン（以下、ＮＭＰと略す）に分散することにより調整した正極活物質ペーストを、正極集電体となる厚み２０μｍのＡｌ箔上に塗布し、正極活物質膜を形成した後乾燥した。更に裏面にも正極活物質ペーストを塗工し乾燥して、Ａｌ箔の両面に正極活物質膜を成形した後、プレスして厚さ１６０μｍの正極を作成した。上記作製した正極を、電極寸法４６ｍｍ×２５８ｍｍに切断し、集電端子を溶接するためと、接着剤未塗布部を設けるために、正極活物質ペーストの未塗工部を電極端部に４６ｍｍ×１５ｍｍ設けた。片面の正極活物質膜の厚みは７０μｍとした。正極のＡｌ箔の未塗工部分の端部にはリードとしての厚み０．１ｍｍ、幅３ｍｍのＡｌ集電端子を超音波溶接により取り付け、図１乃至図３に示すような正極を作製した。
【００１５】
（負極の作製）
メソフェーズカーボンマイクロビーズからなる負極活物質９０重量部とＰＶｄＦ１０重量部をＮＭＰに分散することにより調整した負極活物質ペーストを、負極集電体となる厚さ１０μｍのＣｕ箔の一方に図４〜６のようにパターン塗工し、負極活物質の塗工部と未塗工部を持つ負極活物質膜を形成したあと乾燥した。更に、裏面にも負極活物質ペーストをパターン塗工して乾燥し、Ｃｕ箔の両面に負極活物質膜を形成した後、プレスして負極を作成した。
次に、作製した負極を電極寸法４８ｍｍ×３４０ｍｍに切断した。未塗工部Ｃ及びＤは４８ｍｍ×２９ｍｍ、未塗工部Ｅは４８ｍ×６４ｍｍ、片面の負極活物質膜の厚さは７５μｍとした。未塗工部Ｃ及びＤは巻芯９と同じ幅で、未塗工部Ｅは巻き終えた電極体の最外周の長さである。なお、未塗工部Ｃ乃至Ｅは形成しなくてもかまわないが、電極活物質の有効利用のため形成したほうが望ましい。
次に、負極集電体であるＣｕ箔の未塗工部分Ｃの端部にリードとして厚み０．１ｍｍ、幅３ｍｍの表面をＮｉメッキしたＣｕ集電端子を超音波溶接により取り付けた。
なお、集電端子の取り付け位置は図４乃至図６の位置に限らず、例えば未塗工部Ｅ位置に取り付けてもかまわない。また、集電端子は表面をＮｉメッキしたＣｕに限らずＣｕ、Ｎｉ等の導電性金属でもよい。
【００１６】
（セパレータ付負極の作製）
セパレータとして厚さ２５μｍ、幅４８ｍｍの多孔性ポリエチレンシートを使用し、２枚のセパレータの片面ずつに接着剤を塗布した。接着剤としてはＰＶｄＦを溶解させ、酸化アルミニウム粉末を分散させたＮＭＰ溶液を用いた。この接着剤による接着層は電解液を注液した場合に電解液を保持し、イオン伝導性を有する接着層を形成する。その後、接着剤が乾燥する前に上記作製した負極の両面に密着させ、張り合わせた後乾燥することで図４乃至図６に示すようなセパレータ付負極を作製した。
なお、ここでは電極を切断してからセパレータを接着しているが、セパレータを電極に接着してから切断しても良い。
なお、接着剤は一例であり、ＰＶｄＦに限らず、例えばポリビニルアルコールやポリビニルブチラート、ポリメタクリル酸メチル等の高分子でもよい。
また、酸化アルミニウム粉末は接着層が多孔体になりやすいように添加しており、微粉末であれば黒鉛やシリカゲル等でも良いし、必ずしも添加しなくてもよい。また、溶剤もＮＭＰに限らない。
【００１７】
（渦巻状電極体の作製）
上記のように作製したセパレータ付負極の活物質未塗工部Ｃ及びＤを図７のように対向する２枚の巻芯で挟み、巻芯を半回転させて負極を固定する。接着剤として、ＰＶｄＦを溶解させ、酸化アルミニウムを分散させたＤＭＦ溶液を用いた。この接着剤による接着層は電解液を注液した場合に電解液を保持し、イオン伝導性を有する接着層を形成する。この接着剤を図１の正極のＡ，Ｂの部分以外の両面に塗布して、捲芯に巻き付けた負極の間に挿入し、接着剤を塗布した正極を巻き込みながら長円状に捲き、巻き終わりをテープで止めた。接着剤は図１の正極のＡ，Ｂの部分には塗布せず、巻芯に接着剤が付着する事を防いだ。次に、巻芯を抜き取り、接着剤が乾燥する前に、所定の圧力でプレスする事で仮成形する。その後、所定の圧力で加重をかけながら真空乾燥を行って図８ような接着平板状渦巻電極体を作製した。
このように電極やセパレータの巻芯に接触する部分には接着剤を塗布しないことにより、接着剤塗布面が巻芯に触れないようにすることで量産性の向上とエネルギー密度を向上する事が出来る。
【００１８】
【発明の効果】
以上のように、本発明に係る電池は、絶縁性を有し電解液を保持するセパレータに挟まれた第１の活物質層と第１の集電体とを備えた第１の電極の端部は第１の集電端子に接続され、電解液を保持する接着層に挟まれた第２の活物質層と第２の集電体とを備えた第２の電極の端部は第２の集電端子に接続され、前記第１の電極と前記第２の電極とを巻き込み、前記第１の電極を挟むセパレータと前記第２の電極とを、前記第２の電極を挟む接着層を介して一体化する電池であって、前記第１の電極、あるいは第２の電極を巻き込む中心部には、前記第１の電極の第１の集電端子と、この第１の電極の第１の集電端子に半周遅れた位置に前記第２の電極の第２の集電端子とが配置されており、前記巻き込む中心部の前記第２の電極の端部は前記第２の集電体の露出した部位を有し、この露出した部位が折曲部を構成する構造としたので、巻芯に接着剤が付着するのを防止して電池の生産性及び信頼性、エネルギー密度を向上させることができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１による電池の正極の展開図である。
【図２】本発明の実施の形態１による電池の正極の展開図のX−X'断面図である。
【図３】本発明の実施の形態１による電池の正極の展開図であり、図１の裏面を示す。
【図４】本発明の実施の形態１による電池の負極の展開図である。
【図５】本発明の実施の形態１による電池の負極の展開図のY−Y'断面図である。
【図６】本発明の実施の形態１による電池の負極の展開図であり、図４の裏面を示す。
【図７】本発明の実施の形態１による電池の構造を説明する断面図である。
【図８】本発明の実施の形態１による電池の構造を説明する断面図である。
【図９】従来の渦巻状電極体の構造を説明する断面図である。
【符号の説明】
１正極集電端子、２正極集電体、３正極活物質層、４負極集電端子、５負極集電体、６負極活物質層、７セパレータ、8 保護テープ、９巻芯、１０接着剤、１１折曲部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the structure of a battery having a spiral structure, and in particular, improves the productivity, safety, and energy density of a spiral battery in which a positive electrode or a negative electrode is bonded.
[0002]
[Prior art]
In recent years, in order to reduce the size and thickness of portable electronic devices, there has been a demand for improvement in size and thickness of batteries used as power sources for such electronic devices, particularly secondary batteries that can be repeatedly charged. Lithium ion secondary batteries have attracted attention as batteries that can drive electronic devices for a longer period of time, are lightweight, easy to carry, and have high capacity. Therefore, in the present invention, a lithium ion battery will be described as an example.
[0003]
Bobbin type, laminated type, and spiral type electrode structures are known, consisting of a negative electrode, separator, and positive electrode, but high pulse discharge is generally required for general portable devices such as personal computers and mobile phones. A spiral electrode structure is used.
[0004]
In general, a cylindrical electrode body is often used for the spiral structure. However, in order to reduce the thickness of the electrode body, it is necessary to take up a flat shape or flatten it by pressing. At this time, in order to maintain the shape, it is necessary to maintain the electrode shape by winding and fixing the tape or the like and enclosing it in an outer can, or by adhering the electrode. For example, JP-A-10-302843 discloses an example of the latter structure. The latter has the merit that the shape is maintained without being enclosed in a sturdy outer can. Moreover, it has the merit that the safety | security at the time of a short circuit also increases by adhere | attaching an electrode and a separator.
[0005]
[Problems to be solved by the invention]
When producing a spiral electrode body, a winding core is required to be wound in a spiral shape, and a wound electrode body is created by winding or sandwiching a part of the electrode around the winding core. When the electrode is wound around, the adhesive applied to the electrode adheres to the core, so that the core is not only soiled, but the adhesive adheres to the core and the adhesive is not applied to the electrode. There arises a problem that a part is formed or an adhesive attached to the core adheres to other parts. Moreover, there is a possibility that an internal space is formed between the electrodes due to the hardened adhesive mixed in the electrode body, or the electrode may be short-circuited through the separator. For example, as shown in FIG. 9, when the positive electrode current collector terminal 1 and the positive electrode active material layer 3 are close to each other, the adhesive 10 is also applied onto the positive electrode current collector terminal 1. Therefore, when the positive electrode coated with the adhesive is arranged as shown in FIG. 9 so as not to contact the core, an excess F of the negative electrode is generated.
[0006]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery that has high safety and productivity, and that can obtain a high energy density.
[0007]
[Means for Solving the Problems]
In the first battery according to the present invention, an end portion of a first electrode including a first active material layer and a first current collector sandwiched between separators that have insulating properties and hold an electrolytic solution is An end portion of a second electrode, which is connected to the first current collecting terminal and includes a second active material layer and a second current collector sandwiched between adhesive layers for holding an electrolytic solution, is a second current collector. Connected to an electrical terminal, wraps around the first electrode and the second electrode, and connects the separator sandwiching the first electrode and the second electrode via an adhesive layer sandwiching the second electrode In the battery unit to be integrated, a first current collecting terminal of the first electrode and a first current collecting terminal of the first electrode are disposed at a central portion around which the first electrode or the second electrode is wound. A second current collecting terminal of the second electrode is arranged at a position delayed by a half turn with respect to the electric terminal, and an end portion of the second electrode at the central portion to be wound is the second electrode Has an exposed portion of the current collector, the exposed site is obtained by constituting the bending portion.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a development view of a positive electrode of a battery according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view taken along the line XX ′ of FIG. 1, and FIG. 3 is a development view of the positive electrode. 4 is a development view of the negative electrode of the battery, FIG. 5 is a cross-sectional view taken along line YY ′ of FIG. 4, and FIG. 6 is a development view of the negative electrode, showing the back surface of FIG. In the figure, 1 is a positive electrode current collector terminal, 2 is a positive electrode current collector, 3 is a positive electrode active material layer, 4 is a negative electrode current collector terminal, 5 is a negative electrode current collector, 6 is a negative electrode active material layer, and 7 is a polymer, for example. A separator made of a porous film, 8 is a protective tape. Moreover, the adhesive non-application part A is provided in the part which a positive electrode contacts with a core in the positive electrode shown in FIG. Since the back surface shown in FIG. 3 is not in direct contact with the core, the adhesive-uncoated B may or may not be provided. The uncoated portions C to E of the active material layer in the negative electrode shown in FIGS. 4 to 6 are provided because there is no positive electrode active material facing when the electrode is wound into a spiral electrode body. That is, since the uncoated portions C and D of the active material layer face the winding core, the uncoated portion E of the active material layer hits the outermost layer of the spiral electrode body, so there is no opposing positive electrode. In this example, the separator 7 is bonded to both surfaces of the negative electrode in advance.
[0009]
7 and 8 are cross-sectional views of the battery formed by winding the positive electrode and the negative electrode prepared as described above, in which 9 is a winding core, 10 is an adhesive, and 11 is a bent portion. In this battery, first, the core 9 is bent once by sandwiching the uncoated portions C and D of the active material layer of the negative electrode with the separator between a pair of opposing cores 9. Next, as shown in FIG. 7, the positive electrode in which the adhesive 10 is applied to the positive electrode active material layers 3 on both sides is inserted between the negative electrodes and rolled up. At this time, the adhesive-uncoated portions A and B are provided on the positive electrode in contact with the core. An uncoated portion E of the active material layer of the negative electrode is disposed on the outermost layer. Thereafter, the core 9 is extracted and pressed to be brought into close contact, and a spiral electrode body as shown in FIG. 8 is obtained. By manufacturing the battery in this way, no adhesive layer is formed on the bent portion 11. However, the adhesive layer and the separator are not shown in FIG. The spiral electrode body of FIG. 8 has two negative electrode current collectors 5 with a separator 7 at the center, that is, two negative electrodes in succession, and the tip of the positive electrode current collector 2 is located at a position half a lap behind the tip of the negative electrode. A positive electrode current collector 2 and a negative electrode current collector 5, that is, a positive electrode and a negative electrode are sequentially wound around the outer periphery via a separator. Further, no active material layer is formed outside the outermost current collector 5.
[0010]
According to the present embodiment, the negative electrode with a separator is sandwiched between the core 9 and bent once, and then the positive electrode not coated with the adhesive 10 is inserted into the portion in contact with the core and is wound. Therefore, the adhesive 10 application surface does not touch the core 9, and the adhesive 10 is difficult to adhere to the core 9, the core 9 becomes dirty and the adhesive 10 attached to the core 9 adheres to other parts, Prevents inconveniences such as uncoated areas of adhesive 10 on the electrodes, solidified adhesive 10 mixing inside the electrode body, creating internal spaces between the electrodes, and shorting the electrodes through the separator 7 And a highly reliable battery can be obtained with high productivity. Further, by disposing the positive electrode current collecting terminal 1 at the position shown in FIG. 7, the positive electrode active material 3 and the negative electrode active material 6 can obtain substantially the same facing area, and the energy is not generated because the active material is not wasted. The density can be improved.
[0011]
Further, the outer sides of the outermost layers of the portions A and B facing the core 9 of the electrode (negative electrode in the present embodiment) and the electrode (negative electrode in the present embodiment) that are not expected to have a battery reaction are not active. By not forming the material layer, the volume energy density can be improved.
[0012]
In addition, the workability of entrainment is improved by previously bonding a separator to at least one of the positive electrode and the negative electrode (in this embodiment, the negative electrode).
[0013]
In this embodiment, the negative electrode is used as the first electrode, the separator 7 is bonded in advance, the positive electrode is used as the second electrode, two electrodes are wound, and the adhesive layer is not provided at the bent portion at the center. Although shown, the positive electrode may be the first electrode and the negative electrode may be the second electrode.
[0014]
【Example】
A specific embodiment for forming the battery structure as described above will be described.
(Preparation of positive electrode)
91 parts by weight of a positive electrode active material made of LiCo02, 6 parts by weight of artificial graphite as a conductive agent, and 3 parts by weight of polyvinylidene fluoride (hereinafter abbreviated as PVdF) as a binder are combined with N-methylpyrrolidone (hereinafter referred to as NMP). The positive electrode active material paste prepared by dispersing in abbreviated) was applied onto an Al foil having a thickness of 20 μm to be a positive electrode current collector to form a positive electrode active material film and then dried. Further, a positive electrode active material paste was applied to the back surface and dried to form a positive electrode active material film on both sides of the Al foil, and then pressed to prepare a positive electrode having a thickness of 160 μm. In order to cut the above-prepared positive electrode into an electrode size of 46 mm × 258 mm, weld a current collecting terminal, and provide an adhesive-uncoated portion, an uncoated portion of the positive electrode active material paste is formed at the end of the electrode at 46 mm × 15 mm was provided. The thickness of the positive electrode active material film on one side was 70 μm. An Al current collecting terminal having a thickness of 0.1 mm and a width of 3 mm as a lead was attached to the end of the uncoated portion of the Al foil of the positive electrode by ultrasonic welding to produce a positive electrode as shown in FIGS.
[0015]
(Preparation of negative electrode)
A negative electrode active material paste prepared by dispersing 90 parts by weight of mesophase carbon microbeads and 10 parts by weight of PVdF in NMP was applied to one of 10 μm-thick Cu foils serving as a negative electrode current collector as shown in FIGS. Then, after pattern coating, a negative electrode active material film having a negative electrode active material coated portion and an uncoated portion was formed, and then dried. Further, a negative electrode active material paste was applied on the back surface by pattern coating and dried, and after forming a negative electrode active material film on both surfaces of the Cu foil, the negative electrode was formed by pressing.
Next, the produced negative electrode was cut into an electrode size of 48 mm × 340 mm. The uncoated portions C and D were 48 mm × 29 mm, the uncoated portion E was 48 m × 64 mm, and the thickness of the negative electrode active material film on one side was 75 μm. The uncoated portions C and D have the same width as the core 9, and the uncoated portion E is the length of the outermost periphery of the electrode body that has been wound. The uncoated portions C to E may not be formed, but are preferably formed for effective use of the electrode active material.
Next, a Cu current collector terminal with a surface of Ni having a thickness of 0.1 mm and a width of 3 mm as a lead was attached to the end of an uncoated portion C of the Cu foil as the negative electrode current collector by ultrasonic welding.
In addition, the attachment position of a current collection terminal is not restricted to the position of FIG. 4 thru | or FIG. 6, For example, you may attach to the uncoated part E position. Further, the current collecting terminal is not limited to Cu whose surface is Ni-plated, but may be a conductive metal such as Cu or Ni.
[0016]
(Preparation of negative electrode with separator)
A porous polyethylene sheet having a thickness of 25 μm and a width of 48 mm was used as a separator, and an adhesive was applied to each side of the two separators. As the adhesive, an NMP solution in which PVdF was dissolved and aluminum oxide powder was dispersed was used. The adhesive layer made of this adhesive retains the electrolytic solution when the electrolytic solution is injected, and forms an adhesive layer having ion conductivity. Then, the negative electrode with a separator as shown in FIG. 4 thru | or FIG. 6 was produced by making it closely_contact | adhere to both surfaces of the said produced negative electrode before drying an adhesive agent, bonding, and drying.
Although the separator is bonded after the electrode is cut here, the separator may be bonded to the electrode and then cut.
The adhesive is an example, and is not limited to PVdF, and may be a polymer such as polyvinyl alcohol, polyvinyl butyrate, or polymethyl methacrylate.
Further, the aluminum oxide powder is added so that the adhesive layer is easily formed into a porous body. If it is a fine powder, graphite, silica gel, or the like may be used, or it may not be added. Further, the solvent is not limited to NMP.
[0017]
(Production of spiral electrode body)
The active material uncoated portions C and D of the negative electrode with separator prepared as described above are sandwiched between two opposing cores as shown in FIG. 7, and the negative electrode is fixed by rotating the core halfway. As an adhesive, a DMF solution in which PVdF was dissolved and aluminum oxide was dispersed was used. The adhesive layer made of this adhesive retains the electrolytic solution when the electrolytic solution is injected, and forms an adhesive layer having ion conductivity. This adhesive is applied on both sides of the positive electrode other than the portions A and B of FIG. 1, inserted between the negative electrodes wound around the core, and rolled into an oval shape while winding the positive electrode coated with the adhesive. Tape the end. The adhesive was not applied to the portions A and B of the positive electrode in FIG. 1 to prevent the adhesive from adhering to the core. Next, the winding core is extracted and temporarily molded by pressing at a predetermined pressure before the adhesive is dried. Thereafter, vacuum drying was performed while applying a load at a predetermined pressure to produce a bonded flat spiral electrode body as shown in FIG.
In this way, by not applying the adhesive to the electrode or separator core contact portion, it is possible to improve the mass productivity and energy density by preventing the adhesive application surface from touching the core. I can do it.
[0018]
【The invention's effect】
As described above, the battery according to the present invention has an end of the first electrode including the first active material layer and the first current collector sandwiched between separators that have insulating properties and hold an electrolytic solution. The second electrode is connected to the first current collecting terminal, and the end of the second electrode including the second active material layer and the second current collector sandwiched between the adhesive layers holding the electrolytic solution is the second An adhesive layer sandwiching the second electrode and a separator sandwiching the first electrode between the first electrode and the second electrode. A first current collecting terminal of the first electrode and a first electrode of the first electrode at a central portion around which the first electrode or the second electrode is wound . The second current collecting terminal of the second electrode is disposed at a position delayed by a half turn with respect to the current collecting terminal, and the end portion of the second electrode at the center portion to be wound is It has an exposed portion of the second current collector, since the exposed portion is a structure constituting the folded portion, battery productivity and reliability by preventing the adhesive on the winding core is attached, Energy density can be improved.
[Brief description of the drawings]
FIG. 1 is a development view of a positive electrode of a battery according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view taken along the line XX ′ of the developed view of the positive electrode of the battery according to the first embodiment of the present invention.
FIG. 3 is a development view of the positive electrode of the battery according to Embodiment 1 of the present invention, showing the back surface of FIG.
FIG. 4 is a development view of the negative electrode of the battery according to Embodiment 1 of the present invention.
FIG. 5 is a YY ′ cross-sectional view of a developed view of the negative electrode of the battery according to Embodiment 1 of the present invention.
6 is a development view of the negative electrode of the battery according to Embodiment 1 of the present invention, showing the back side of FIG. 4;
FIG. 7 is a cross-sectional view illustrating the structure of a battery according to Embodiment 1 of the present invention.
FIG. 8 is a cross-sectional view illustrating the structure of a battery according to Embodiment 1 of the present invention.
FIG. 9 is a cross-sectional view illustrating the structure of a conventional spiral electrode body.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Positive electrode current collector terminal, 2 Positive electrode current collector, 3 Positive electrode active material layer, 4 Negative electrode current collection terminal, 5 Negative electrode current collector, 6 Negative electrode active material layer, 7 Separator, 8 Protective tape, 9 Winding core, 10 Adhesive 11 Folding part

Claims

絶縁性を有し電解液を保持するセパレータに挟まれた第１の活物質層と第１の集電体とを備えた第１の電極の端部は第１の集電端子に接続され、電解液を保持する接着層に挟まれた第２の活物質層と第２の集電体とを備えた第２の電極の端部は第２の集電端子に接続され、前記第１の電極と前記第２の電極とを長円状に巻き込み、前記第１の電極を挟むセパレータと前記第２の電極とを、前記第２の電極を挟む接着層を介して一体化する電池であって、
前記第１の電極、あるいは第２の電極を前記長円状に巻き込む中心部には、前記第１の電極の第１の集電端子と、この第１の電極の第１の集電端子に半周遅れた位置に前記第２の電極の第２の集電端子とが配置されており、前記巻き込む中心部の前記第２の電極の端部は前記第２の活物質層と前記接着層とが形成されていない前記第２の集電体が露出した部位を有し、この露出した部位が前記長円状に巻き込まれたときの折曲部を構成することを特徴とする電池。An end portion of the first electrode provided with a first active material layer and a first current collector sandwiched between separators having insulating properties and holding an electrolyte solution is connected to the first current collector terminal, An end portion of a second electrode including a second active material layer and a second current collector sandwiched between adhesive layers that hold an electrolytic solution is connected to a second current collecting terminal, and the first current collecting terminal is connected to the first current collecting terminal. A battery in which an electrode and the second electrode are wound in an oval shape, and a separator that sandwiches the first electrode and the second electrode are integrated via an adhesive layer that sandwiches the second electrode. And
In the central part where the first electrode or the second electrode is wound into the ellipse , the first current collecting terminal of the first electrode and the first current collecting terminal of the first electrode The second current collecting terminal of the second electrode is arranged at a position delayed by a half circumference, and the end of the second electrode at the center of the winding is formed by the second active material layer and the adhesive layer. The battery has a portion where the second current collector not formed with an exposed portion, and the exposed portion constitutes a bent portion when wound into the ellipse .