JPH0992288A - Electrode film for nonaqueous electrolyte secondary battery - Google Patents
Electrode film for nonaqueous electrolyte secondary batteryInfo
- Publication number
- JPH0992288A JPH0992288A JP7248180A JP24818095A JPH0992288A JP H0992288 A JPH0992288 A JP H0992288A JP 7248180 A JP7248180 A JP 7248180A JP 24818095 A JP24818095 A JP 24818095A JP H0992288 A JPH0992288 A JP H0992288A
- Authority
- JP
- Japan
- Prior art keywords
- binder
- electrode film
- electrolyte secondary
- secondary battery
- nonaqueous electrolyte
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】ニッケル・カドミウム電池な
どに代わる二次電池として、例えば負極にリチウムイオ
ンを吸蔵放出可能な炭素材料を用い、正極にリチウムコ
バルト複合酸化物等のリチウム複合酸化物を用いた非水
電解液二次電池用の電極フィルムに関するものである。BACKGROUND OF THE INVENTION As a secondary battery replacing a nickel-cadmium battery or the like, for example, a carbon material capable of inserting and extracting lithium ions is used for the negative electrode, and a lithium composite oxide such as a lithium cobalt composite oxide is used for the positive electrode. The present invention relates to an electrode film for a non-aqueous electrolyte secondary battery.
【０００２】[0002]
【従来の技術】近年、電子機器の小型化・高性能化が進
み、これら電子機器に搭載される二次電池に対して高エ
ネルギー化や小型軽量化の要求が強まっている。従来、
これらの電子機器には、ニッケル・カドミウム二次電池
や鉛二次電池が使用されているが、これらの二次電池は
放電電圧が低く、小型軽量・高エネルギー化の期待に沿
えていない。最近、これらの二次電池に代わるものとし
て、負極にリチウムイオンを吸蔵放出可能な炭素材料を
用い、正極にリチウムコバルト複合酸化物等のリチウム
複合酸化物を用いた非水電解液二次電池の開発がなされ
ている。この非水電解液二次電池は、高い放電電圧と高
エネルギー密度を有しており、二次電池に対する高エネ
ルギー化や小型軽量化の要求に沿うものと期待されてい
る。2. Description of the Related Art In recent years, miniaturization and high performance of electronic devices have been advanced, and demands for high energy, small size, and light weight of secondary batteries mounted on these electronic devices have increased. Conventionally,
These electronic devices use nickel-cadmium secondary batteries or lead secondary batteries, but these secondary batteries have a low discharge voltage and do not meet the expectation of small size, light weight and high energy. Recently, as an alternative to these secondary batteries, non-aqueous electrolyte secondary batteries using a lithium composite oxide such as lithium cobalt composite oxide for the positive electrode using a carbon material capable of inserting and extracting lithium ions for the negative electrode Development is being done. This non-aqueous electrolyte secondary battery has a high discharge voltage and a high energy density, and is expected to meet the demand for higher energy and smaller and lighter secondary batteries.
【０００３】従来の非水電解液二次電池に使用されてい
る電極フィルムの概要を負極フィルムを例にとって述べ
る。負極フィルムは、優れた可とう性やリチウムの析出
の恐れが少ないことから、コークス・黒鉛・炭素繊維等
の炭素材料が好ましく使用され、これらの炭素材料を結
着剤溶液に分散させて炭素粒子スラリーとしたものを集
電体金属箔上に塗布し、溶剤を乾燥後、ローラープレス
機により圧縮成形して電極を得る方法等により作製され
る。従来は、結着剤溶液として、ポリフッ化ビニリデン
（ＰＶＤＦ）をＮ−メチル−２−ピロリドン（ＮＭＰ）
に溶解した溶液やポリテトラフルオロエチレン（ＰＴＦ
Ｅ）のディスパージョン溶液等のフッ素樹脂系が多く使
用されてきた。しかし、結着剤としてＰＶＤＦやＰＴＦ
Ｅ等のフッ素樹脂を使用した場合、可とう性は優れてい
るものの、集電体金属箔との密着性が劣るため、充放電
を繰り返すと炭素粒子が集電体金属箔から剥離・脱落し
て電池容量が次第に低下するという問題があった。更
に、種々の要因で電池内の温度が異常に上昇した場合、
結着剤中のＰＶＤＦやＰＴＦＥが分解してフッ化水素
（ＨＦ）が発生し、負極上に析出したリチウムと反応・
発熱してしまうため、電池が破裂する恐れがあった。An outline of an electrode film used in a conventional non-aqueous electrolyte secondary battery will be described by taking a negative electrode film as an example. For the negative electrode film, carbon materials such as coke, graphite, and carbon fiber are preferably used because of their excellent flexibility and little risk of lithium precipitation.These carbon materials are dispersed in a binder solution to form carbon particles. A slurry is applied on a current collector metal foil, and the solvent is dried. The slurry is then compression molded by a roller press to obtain an electrode. Conventionally, polyvinylidene fluoride (PVDF) is used as a binder solution and N-methyl-2-pyrrolidone (NMP) is used.
Solution or polytetrafluoroethylene (PTF)
Fluororesin systems such as the dispersion solution of E) have been widely used. However, as a binder PVDF or PTF
When a fluororesin such as E is used, the flexibility is excellent, but the adhesion with the current collector metal foil is poor, so carbon particles peel and fall off from the current collector metal foil after repeated charge and discharge. There was a problem that the battery capacity gradually decreased. Furthermore, if the temperature inside the battery rises abnormally due to various factors,
PVDF or PTFE in the binder decomposes to generate hydrogen fluoride (HF), which reacts with the lithium deposited on the negative electrode.
Since the heat is generated, the battery may explode.
【０００４】[0004]
【発明が解決しようとする課題】充放電を繰り返しても
電極中の炭素粒子等が集電体金属箔から剥離・脱落して
電池容量が次第に低下することがない、集電体金属箔と
の密着性が高く、屈曲性に富み、電池内の温度が異常上
昇した場合にも電池が破裂する危険性が少ない、安全性
の高い非水電解液二次電池用の電極フィルムを提供す
る。With the current collector metal foil, carbon particles and the like in the electrode do not peel off / fall off from the current collector metal foil even when charging / discharging is repeated, and the battery capacity gradually decreases. (EN) Provided is an electrode film for a non-aqueous electrolyte secondary battery, which has high adhesiveness, is highly flexible, and has a low risk of the battery exploding even when the temperature inside the battery abnormally rises, and which is highly safe.
【０００５】[0005]
【課題を解決するための手段】少なくともリチウム複合
酸化物と導電剤と結着剤よりなる活物質層を集電体上に
設けてなる正極と、少なくともリチウムイオンを吸蔵放
出可能な炭素材料と結着剤よりなる炭素粒子層を集電体
上に設けてなる負極と、非水電解液とを有する非水電解
液二次電池において、該結着剤がスチレン系熱可塑性エ
ラストマーからなり、更に結着剤であるスチレン系熱可
塑性エラストマーの破断伸度が３００％以上、破断強度
が５０ｋｇｆ／ｃｍ2以上であり、スチレン系熱可塑性
エラストマーの無水マレイン酸変性した酸価が２ｍｇＣ
Ｈ3ＯＮａ／ｇ以上である非水電解液二次電池用電極フ
ィルムである。A positive electrode having an active material layer comprising at least a lithium composite oxide, a conductive agent and a binder on a current collector, and a carbon material capable of inserting and extracting at least lithium ions. In a non-aqueous electrolyte secondary battery having a negative electrode having a carbon particle layer made of a binder provided on a current collector and a non-aqueous electrolyte, the binder is made of a styrene-based thermoplastic elastomer, and a binder The breaking elongation of the styrene-based thermoplastic elastomer as a binder is 300% or more, the breaking strength is 50 kgf / cm 2 or more, and the maleic anhydride-modified acid value of the styrene-based thermoplastic elastomer is 2 mgC.
It is an electrode film for a non-aqueous electrolyte secondary battery having H 3 ONa / g or more.
【０００６】[0006]
【発明の実施の形態】本発明で用いる結着剤としては、
硬質相にポリスチレン、軟質相にポリブタジエン、ポリ
イソプレンあるいはポリブタジエンブロックの二重結合
を水素添加により飽和させたスチレン系熱可塑性エラス
トマーが使用される。一般に熱可塑性エラストマーは、
ゴム弾性を示す均質な軟質相に三次元網目の結び目とな
る硬質相が分散した二層構造を示し、ゴムとプラスチッ
クの中間領域に存在する。例えばポリスチレン−ポリブ
タジエン−ポリスチレンのトリブロック共重合体では、
ポリブタジエンの海相中にポリスチレンの島相がミクロ
ドメイン的に分散した状態となり、ミクロドメイン同士
がトリブロック共重合体で連結した物理的な架橋構造を
形成する。このような架橋構造のため加硫ゴムのような
高弾性・高強度を発現する。特にスチレン系熱可塑性エ
ラストマーは、加硫ゴムに近い性質を持っており、トル
エン、キシレン等の汎用の有機溶剤に容易に溶解するの
で溶液製膜方法には好適である。ところで、本発明のス
チレン系熱可塑性エラストマーの結着剤の代わりに加硫
ゴムを使用することが考えられるが、加硫ゴムを使用し
た場合、非常に長時間の加硫工程が必要となり生産性、
安定性等に問題があるため好ましくない。BEST MODE FOR CARRYING OUT THE INVENTION As the binder used in the present invention,
Polystyrene is used as the hard phase, and styrene-based thermoplastic elastomer in which the double bond of polybutadiene, polyisoprene or polybutadiene block is saturated by hydrogenation is used as the soft phase. Generally, thermoplastic elastomers are
It exhibits a two-layer structure in which a homogeneous soft phase exhibiting rubber elasticity and a hard phase serving as a knot of a three-dimensional network are dispersed, and exists in an intermediate region between rubber and plastic. For example, in a polystyrene-polybutadiene-polystyrene triblock copolymer,
The islands of polystyrene are dispersed in the sea phase of polybutadiene in the form of microdomains, forming a physical crosslinked structure in which the microdomains are linked by a triblock copolymer. Due to such a cross-linked structure, it exhibits high elasticity and high strength like vulcanized rubber. In particular, the styrene-based thermoplastic elastomer has properties close to those of vulcanized rubber and is easily dissolved in a general-purpose organic solvent such as toluene and xylene, and is suitable for a solution film-forming method. By the way, it is conceivable to use vulcanized rubber instead of the binder of the styrene-based thermoplastic elastomer of the present invention, but when vulcanized rubber is used, a very long vulcanization step is required and productivity is increased. ,
This is not preferable because of problems with stability and the like.
【０００７】本発明に使用されるスチレン系熱可塑性エ
ラストマーは、破断伸度が３００％以上で、破断強度が
５０ｋｇｆ／ｃｍ2以上の機械特性を持つものが好まし
く、特に好ましくは破断伸度が５００％以上で、破断強
度が１００ｋｇｆ／ｃｍ2以上の機械特性を持つもので
ある。破断伸度が３００％未満のものや、破断強度が５
０ｋｇｆ／ｃｍ2未満のものは、電極フィルムを電池セ
ルに組み込む際に、屈曲性や密着性が不足し、炭素粒子
等が集電体金属箔から剥離・脱落する恐れがある。更
に、本発明に使用されるスチレン系熱可塑性エラストマ
ーは、無水マレイン酸変性した酸価が２ｍｇＣＨ3ＯＮ
ａ／ｇ以上のものが好ましく使用される。官能基を付与
していないスチレン系熱可塑性エラストマーでも十分性
能は発揮されるが、無水マレイン酸変性した酸価が２ｍ
ｇＣＨ3ＯＮａ／ｇ以上のものを使用することによって
官能基を付与することができ、集電体金属箔との密着性
や電池セル組立時の屈曲性等を極めて向上することがで
きる。また、本発明に使用されるスチレン系熱可塑性エ
ラストマーは、従来の電池に使用されているＰＶＤＦ等
のフッ素系結着剤と異なり、分子中にフッ素を含有しな
いため、電池内の温度が異常上昇した場合にも分解した
フッ素による悪影響が無い。The styrene-based thermoplastic elastomer used in the present invention preferably has a breaking elongation of 300% or more and a breaking strength of 50 kgf / cm 2 or more, and particularly preferably has a breaking elongation of 500. %, The breaking strength is 100 kgf / cm 2 or more. Those with a breaking elongation of less than 300% or a breaking strength of 5
If it is less than 0 kgf / cm 2 , flexibility and adhesion are insufficient when the electrode film is incorporated into a battery cell, and carbon particles or the like may be peeled off from the current collector metal foil. Further, the styrene-based thermoplastic elastomer used in the present invention has a maleic anhydride-modified acid value of 2 mg CH 3 ON.
Those having a / g or more are preferably used. Styrene-based thermoplastic elastomers with no functional groups will exhibit sufficient performance, but the acid value modified with maleic anhydride will be 2m.
By using gCH 3 ONa / g or more, a functional group can be added, and the adhesion with the metal foil of the current collector, the flexibility during battery cell assembly, etc. can be extremely improved. In addition, the styrene-based thermoplastic elastomer used in the present invention does not contain fluorine in the molecule unlike the fluorine-based binders such as PVDF used in conventional batteries, so that the temperature inside the battery rises abnormally. Even if it does, there is no adverse effect of decomposed fluorine.
【０００８】次に電極フィルムの製造方法を具体的に述
べる。まず、負極フィルムの製造方法の一例を述べる。
本発明の負極フィルムのリチウムイオンを吸蔵放出可能
な炭素材料の粒子としては、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）、熱分解炭素
類、黒鉛、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、フラン樹脂等を焼成し、炭素化した
もの）、炭素繊維、活性炭等が挙げられる。この中でも
黒鉛がリチウムの吸蔵放出量が多い点で好ましい。黒鉛
の平均粒径は０．５〜２０μｍが好ましく、特に好まし
くは３〜１０μｍである。黒鉛の平均粒径が０．５μｍ
未満の場合は、黒鉛の凝集や分散不良等の問題が起きや
すく、２０μｍを超えると塗工面の状態や塗工性等に悪
影響を及ぼす。例えば、スチレン系熱可塑性エラストマ
ーのトルエン溶液に上記炭素材料を分散させて炭素粒子
スラリーとしたものを集電体金属箔となる厚さ１２μｍ
の電解銅箔上に塗布し、溶剤を乾燥後、ローラープレス
機により所望の空隙度まで圧縮成形して得る方法等によ
り作製される。スチレン系熱可塑性エラストマーは、炭
素材料１００重量部に対して、０．５〜１５重量部使用
され、好ましくは３〜１２重量部使用する。過剰になる
と電気絶縁性が大きくなり容量の低下の原因になるので
１５重量部を越える添加は好ましくない。炭素材料を分
散安定性のためには無水マレイン酸変性した酸価が２ｍ
ｇＣＨ3ＯＮａ／ｇ以上のスチレン系熱可塑性エラスト
マーを用いることが好ましい。Next, a method for manufacturing the electrode film will be specifically described. First, an example of a method for manufacturing a negative electrode film will be described.
The particles of the carbon material capable of inserting and extracting lithium ions in the negative electrode film of the present invention include cokes (pitch coke, needle coke, petroleum coke, etc.), pyrolytic carbons, graphite, glassy carbons, organic polymer compounds. Examples include fired bodies (carbonized products obtained by firing phenol resin, furan resin, etc.), carbon fibers, activated carbon, and the like. Among these, graphite is preferred because it has a large amount of insertion and extraction of lithium. The average particle size of graphite is preferably 0.5 to 20 μm, particularly preferably 3 to 10 μm. Average particle size of graphite is 0.5 μm
If it is less than 20 μm, problems such as agglomeration of graphite and poor dispersion are likely to occur, and if it exceeds 20 μm, the state of the coated surface and coatability are adversely affected. For example, a carbon particle slurry obtained by dispersing the above carbon material in a toluene solution of a styrene-based thermoplastic elastomer is used as a current collector metal foil and has a thickness of 12 μm.
It is prepared by a method such as coating on the electrolytic copper foil, drying the solvent, and then compression molding to a desired porosity with a roller press machine. The styrene-based thermoplastic elastomer is used in an amount of 0.5 to 15 parts by weight, preferably 3 to 12 parts by weight, based on 100 parts by weight of the carbon material. If the amount is excessive, the electrical insulating property is increased and the capacity is lowered. Therefore, addition in excess of 15 parts by weight is not preferable. The acid value of the maleic anhydride modified carbon material is 2m for dispersion stability.
It is preferable to use a styrene-based thermoplastic elastomer of gCH 3 ONa / g or more.
【０００９】次に正極フィルムの製造方法の一例を述べ
る。本発明の正極フィルムには、例えば、正極活物質の
ＬｉＸＯ2(Ｘ＝Ｃｏ、Ｎｉ、Ｍｎ等の遷移金属の一種又
は複数種）と黒鉛等の導電剤をスチレン系熱可塑性エラ
ストマーのトルエン溶溶液に分散させてスラリーとした
ものを集電体金属箔となる厚さ２０μｍのアルミニウム
箔上に塗布し、溶剤を乾燥後、ローラープレス機により
所望の空隙度まで圧縮成形して得る方法等により作製さ
れる。スチレン系熱可塑性エラストマーは、正極活物質
１００重量部に対して、０．５〜１５重量部使用され、
好ましくは３〜１２重量部使用する。過剰になると電気
絶縁性が大きくなり容量の低下の原因になるので１５重
量部を越える添加は好ましくない。正極側も正極活物質
の分散安定性のためには無水マレイン酸変性した酸価が
２ｍｇＣＨ3ＯＮａ／ｇ以上のスチレン系熱可塑性エラ
ストマーを用いることが好ましい。Next, an example of a method for producing the positive electrode film will be described. In the positive electrode film of the present invention, for example, LiXO 2 (one or more kinds of transition metals such as X = Co, Ni, Mn) as a positive electrode active material and a conductive agent such as graphite are dissolved in a toluene solution of a styrene-based thermoplastic elastomer. It is prepared by a method in which a slurry obtained by dispersing the above into a current collector metal foil is applied onto an aluminum foil having a thickness of 20 μm, and the solvent is dried, followed by compression molding to a desired porosity with a roller press machine. To be done. The styrene-based thermoplastic elastomer is used in an amount of 0.5 to 15 parts by weight based on 100 parts by weight of the positive electrode active material,
Preferably 3 to 12 parts by weight are used. If the amount is excessive, the electrical insulating property is increased and the capacity is lowered. Therefore, addition in excess of 15 parts by weight is not preferable. On the positive electrode side as well, in order to stabilize the dispersion of the positive electrode active material, it is preferable to use a styrene-based thermoplastic elastomer modified with maleic anhydride and having an acid value of 2 mg CH 3 ONa / g or more.
【００１０】以上のようにして製造された電極フィルム
を微多孔性ポリプロピレンフィルム製等のセパレータを
介して、例えばＬｉＣｌＯ4、ＬｉＡｓＦ6、ＬｉＰＦ6、Ｌ
ｉＰＦ4、ＬｉＢＦ4、ＬｉＢ（Ｃ6Ｈ5)4、ＬｉＣｌ、Ｌｉ
Ｂｒ、ＣＨ3ＳＯ3Lｉ、ＣＦ3ＳＯ3Lｉ等のリチウム塩を
電解質とし、これを例えばプロピレンカーボネート、エ
チレンカーボネート、１，２−ジメトキシエタン、１，
２−ジエトキシエタン、ジエチルカーボネート、γ−ブ
チルラクトン、テトラヒドロフラン、１，３−ジオキソ
ラン、４−メチル−１，３−ジオキソラン、ジエチルエ
ーテル、スルホラン、メチルスルホラン、アセトニトリ
ル、プロピオニトリル等の単独もしくは二種類以上の混
合溶媒に溶解した非水系電解液に浸せきして電池を作製
する。The electrode film produced as described above is, for example, LiClO 4 , LiAsF 6 , LiPF 6 , and LPF via a separator made of a microporous polypropylene film or the like.
iPF 4 , LiBF 4 , LiB (C 6 H 5 ) 4 , LiCl, Li
A lithium salt such as Br, CH 3 SO 3 Li, CF 3 SO 3 Li or the like is used as an electrolyte, and this is used, for example, as propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,
2-diethoxyethane, diethyl carbonate, γ-butyl lactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, etc., alone or in combination. A battery is manufactured by immersing it in a non-aqueous electrolytic solution dissolved in a mixed solvent of at least one kind.
【００１１】[0011]
【実施例】以下本発明を実施例及び比較例により、更に
詳細に説明するが、本発明はこれらに限定されるもので
はない。 《実施例１》 ＜負極フィルムの作製＞結着剤として破断伸度６５０
％、破断強度１１０ｋｇｆ／ｃｍ2、酸価１０ｍｇＣＨ3
ＯＮａ／ｇの無水マレイン酸変性ポリブタジエンブロッ
ク水素添加スチレン系熱可塑性エラストマー（商品名：
タフテックＭ１９４３［旭化成工業（株）製］）１０重
量部をトルエンに溶解させた樹脂溶液に平均粒径７μｍ
の黒鉛粒子１００重量部を分散させて炭素粒子スラリー
とした後、集電体金属箔となる厚さ１２μｍの電解銅箔
上に塗布し、溶剤を乾燥後、ローラープレス機により圧
縮成形して負極フィルムを作製した。 成形後の炭素粒
子層の厚さは２００μｍであり、炭素粒子層の密度は
１．５１ｇ／ｃｍ3であった。 ＜正極フィルムの作製＞結着剤として負極フィルムと同
一のポリブタジエンブロック水素添加スチレン系熱可塑
性エラストマー（商品名：タフテックＭ１９４３［旭化
成工業（株）製］）１０重量部をトルエンに溶解させた
樹脂溶液に、正極活物質としてＬｉＣｏＯ2を１００重
量部と、導電剤として黒鉛６．６重量部とを分散させて
活物質スラリーとした後、集電体金属箔となる厚さ２０
μｍのアルミニウム箔上に塗布し、溶剤を乾燥後、ロー
ラープレス機により圧縮成形して正極フィルムを作製し
た。成形後の活物質層の厚さは１８０μｍであり、活物
質層の密度は３．６０ｇ／ｃｍ3であった。EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. << Example 1 >><Production of negative electrode film> Elongation at break 650 as a binder
%, Breaking strength 110 kgf / cm 2 , acid value 10 mg CH 3
ONa / g maleic anhydride modified polybutadiene block hydrogenated styrene thermoplastic elastomer (trade name:
Tough tech M1943 [Asahi Kasei Kogyo KK] 10 parts by weight dissolved in toluene is added to a resin solution to give an average particle size of 7 μm.
100 parts by weight of the graphite particles are dispersed to form a carbon particle slurry, which is then applied onto an electrolytic copper foil having a thickness of 12 μm to be a collector metal foil, dried with a solvent, and then compression-molded with a roller press machine to form a negative electrode. A film was made. The thickness of the carbon particle layer after molding was 200 μm, and the density of the carbon particle layer was 1.51 g / cm 3 . <Production of Positive Electrode Film> 10 parts by weight of the same polybutadiene block hydrogenated styrene thermoplastic elastomer (trade name: Tuftec M1943 [manufactured by Asahi Chemical Industry Co., Ltd.]) as a binder as a binder was dissolved in toluene to obtain a resin solution. Then, 100 parts by weight of LiCoO 2 as a positive electrode active material and 6.6 parts by weight of graphite as a conductive agent are dispersed into an active material slurry, and a thickness of a collector metal foil having a thickness of 20 is obtained.
A positive electrode film was prepared by applying the solution on a μm aluminum foil, drying the solvent, and then compression-molding it with a roller press. The thickness of the active material layer after molding was 180 μm, and the density of the active material layer was 3.60 g / cm 3 .
【００１２】《比較例１》 ＜負極フィルムの作製＞結着剤として破断伸度２５０
％、破断強度１４０ｋｇｆ／ｃｍ2のＰＶＤＦ（商品
名：ＫＦポリマーＷ＃１３００［呉羽化学工業（株）
製］）１０重量部をＮＭＰに溶解させた樹脂溶液に平均
粒径７μｍの黒鉛粒子１００重量部を分散させて炭素粒
子スラリーとした後、集電体金属箔となる厚さ１２μｍ
の電解銅箔上に塗布し、溶剤を乾燥後、ローラープレス
機により圧縮成形して負極フィルムを作製した。 成形
後の炭素粒子層の厚さは２００μｍであり、炭素粒子層
の密度は１．５５ｇ／ｃｍ3であった。 ＜正極フィルムの作製＞結着剤として負極フィルムと同
一のＰＶＤＦ（商品名：ＫＦポリマーＷ＃１３００［呉
羽化学工業（株）製］）１０重量部をＮＭＰに溶解させ
た樹脂溶液に、正極活物質としてＬｉＣｏＯ2を１００
重量部と、導電剤として黒鉛６．６重量部とを分散させ
て活物質スラリーとした後、集電体金属箔となる厚さ２
０μｍのアルミニウム箔上に塗布し、溶剤を乾燥後、ロ
ーラープレス機により圧縮成形して正極フィルムを作製
した。 成形後の活物質層の厚さは１８０μｍであり、
活物質層の密度は３．６３ｇ／ｃｍ3であった。Comparative Example 1 <Preparation of Negative Electrode Film> Elongation at Break 250 as Binder
%, PVDF with a breaking strength of 140 kgf / cm 2 (trade name: KF Polymer W # 1300 [Kureha Chemical Industry Co., Ltd.]
]) 10 parts by weight of graphite particles having an average particle size of 7 μm are dispersed in a resin solution having 10 parts by weight dissolved in NMP to form a carbon particle slurry, and a current collector metal foil has a thickness of 12 μm.
Was applied on an electrolytic copper foil, and the solvent was dried, followed by compression molding with a roller press to produce a negative electrode film. The thickness of the formed carbon particle layer was 200 μm, and the density of the carbon particle layer was 1.55 g / cm 3 . <Production of Positive Electrode Film> 10 parts by weight of PVDF (trade name: KF polymer W # 1300 [Kureha Chemical Industry Co., Ltd.]), which is the same as the negative electrode film, was used as a binder in a resin solution prepared by dissolving NMP in the positive electrode LiCoO 2 100 as a substance
2 parts by weight of graphite and 6.6 parts by weight of graphite as a conductive agent are dispersed to form an active material slurry, and a thickness of a current collector metal foil 2
It was applied on a 0 μm aluminum foil, dried with a solvent, and then compression-molded with a roller press to prepare a positive electrode film. The thickness of the active material layer after molding is 180 μm,
The density of the active material layer was 3.63 g / cm 3 .
【００１３】＜集電体金属箔との密着強度の測定＞実施
例１及び比較例１の各々で作製した電極フィルムの表面
に粘着テープを貼り付け、３００ｍｍ／ｍｉｎの速度で
１８０°方向に引張り、密着強度を測定した。その結果
を表１に示す。<Measurement of Adhesion Strength with Current Collector Metal Foil> An adhesive tape was attached to the surface of the electrode film produced in each of Example 1 and Comparative Example 1, and pulled in the 180 ° direction at a speed of 300 mm / min. The adhesion strength was measured. Table 1 shows the results.
【００１４】 表１．電極フィルムの密着強度 [単位：kg/cm] ──────────────────────────── 実施例１ 比較例１ ──────────────────────────── 負 極 正 極 負 極 正 極 2.03 1.98 0.78 0.65 ──────────────────────────── 実施例１の電極フィルムは、比較例１の電極フィルムに
比べて集電体金属箔との密着強度が３倍程度高くなるこ
とが確認された。Table 1. Adhesion strength of electrode film [unit: kg / cm] ──────────────────────────── Example 1 Comparative Example 1 ──── ──────────────────────── Negative pole Positive pole Negative pole Positive pole 2.03 1.98 0.78 0.65 ────────────── ────────────── It was confirmed that the electrode film of Example 1 had about three times higher adhesion strength with the current collector metal foil than the electrode film of Comparative Example 1. It was
【００１５】＜充放電サイクル特性の確認＞実施例１及
び比較例１で作製した電極フィルムを使用し、非水電解
液二次電池を作製して、充電電流６０ｍＡで、充電終止
電圧４．２Ｖまで充電した後、放電電流２００ｍＡで、
放電終止電圧２．５Ｖまで放電する工程を１サイクルと
するサイクル試験を行い、充放電サイクル特性を調べ
た。その結果を表２に示す。<Confirmation of Charge / Discharge Cycle Characteristics> Using the electrode films prepared in Example 1 and Comparative Example 1, a non-aqueous electrolyte secondary battery was prepared, and the charging end voltage was 4.2 V at a charging current of 60 mA. After charging up to 200mA,
A cycle test in which the process of discharging to a discharge end voltage of 2.5 V was defined as one cycle was performed to examine the charge / discharge cycle characteristics. The results are shown in Table 2.
【００１６】 表２．充放電サイクル特性 [単位：mAh/g] ────────────────────────────── サイクル数 実施例１ 比較例１ ────────────────────────────── ５０サイクル ３７０ ３５１ １００サイクル ３６８ ３４５ ５００サイクル ３６７ ２９８ １０００サイクル ３６７ １８９ ────────────────────────────── 実施例１の電極フィルムは、１０００サイクル目でも容
量低下が殆ど認められないのに対し、比較例１の電極フ
ィルムでは、１０００サイクル目においては、かなりの
容量低下が認められる。１０００サイクル終了後の電極
フィルムを取り出して観察すると、実施例１の電極フィ
ルムは何ら変化がないのに対し、比較例１の電極フィル
ムは粒子の剥離・脱落が認められた。このことより実施
例１の電極フィルムが集電体金属箔との密着性に優れて
いることが確認された。Table 2. Charge / Discharge Cycle Characteristics [Unit: mAh / g] ────────────────────────────── Cycle number Example 1 Comparative example 1 ─ ───────────────────────────── 50 cycles 370 351 100 cycles 368 345 500 cycles 367 298 1000 cycles 367 189 ───── ───────────────────────── In the electrode film of Example 1, almost no decrease in capacity was observed even at the 1000th cycle, while in Comparative Example. In the electrode film No. 1, a considerable capacity decrease is recognized at the 1000th cycle. When the electrode film after 1000 cycles was taken out and observed, the electrode film of Example 1 did not change at all, whereas the electrode film of Comparative Example 1 was found to have particles peeled / dropped off. From this, it was confirmed that the electrode film of Example 1 had excellent adhesion to the metal foil of the current collector.
【００１７】＜信頼性試験＞実施例１及び比較例１で作
製した電極フィルムを使用した電池をオーブン中に入
れ、室温から１５０℃まで昇温速度５℃／ｍｉｎで昇温
させたところ、実施例１の電極フィルムを使用した電池
は何ら変化が認められなかったのに対し、比較例１の電
極フィルムを使用した電池は１３０℃の時点で電池蓋が
飛んだ。このことより、実施例１の電極フィルムは、安
全性が高いのに対して、比較例１の電極フィルムは、電
池内の温度が異常上昇した場合に、電池が破裂する危険
性があることが分かる。<Reliability Test> The batteries using the electrode films prepared in Example 1 and Comparative Example 1 were placed in an oven and heated from room temperature to 150 ° C. at a heating rate of 5 ° C./min. The battery using the electrode film of Example 1 did not show any change, whereas the battery using the electrode film of Comparative Example 1 had the battery lid blown off at 130 ° C. From this, the electrode film of Example 1 is highly safe, whereas the electrode film of Comparative Example 1 may have a risk of bursting when the temperature inside the battery rises abnormally. I understand.
【００１８】[0018]
【発明の効果】本発明の非水電解液二次電池用電極フィ
ルムは、結着剤として従来のＰＶＤＦ等のフッ素系結着
剤に代えて、スチレン系熱可塑性エラストマーを使用し
ているので、集電体金属箔との密着力や屈曲性に優れて
いる。このため、充放電を繰り返しても炭素粒子等が集
電体金属箔から剥離・脱落することなく、電池容量が低
下しにくいという利益が得られる。更に、ＰＶＤＦ等の
フッ素系結着剤と異なり、分子中にフッ素を含有しない
ため、電池内の温度が異常上昇した場合にも、ＰＶＤＦ
のように結着剤の熱分解により生成したフッ化水素とリ
チウムが反応して電池が破裂するという危険性がない信
頼性が高い電池が作製可能となる。The electrode film for a non-aqueous electrolyte secondary battery of the present invention uses a styrene-based thermoplastic elastomer instead of a conventional fluorine-based binder such as PVDF as a binder. Excellent adhesion and flexibility with the current collector metal foil. Therefore, even if the charge and discharge are repeated, the carbon particles and the like are not peeled off from the current collector metal foil, and the battery capacity is less likely to decrease. Furthermore, unlike fluorine-based binders such as PVDF, since it does not contain fluorine in the molecule, PVDF can be used even when the temperature inside the battery rises abnormally.
As described above, it is possible to manufacture a highly reliable battery without the risk that the hydrogen fluoride generated by the thermal decomposition of the binder reacts with lithium to burst the battery.
Claims (3)
と結着剤よりなる活物質層を集電体上に設けてなる正極
と、少なくともリチウムイオンを吸蔵放出可能な炭素材
料と結着剤よりなる炭素粒子層を集電体上に設けてなる
負極と、非水電解液とを有する非水電解液二次電池にお
いて、該結着剤がスチレン系熱可塑性エラストマーから
なることを特徴とする非水電解液二次電池用電極フィル
ム。1. A positive electrode comprising an active material layer comprising at least a lithium composite oxide, a conductive agent and a binder on a current collector, and a carbon material capable of inserting and extracting at least lithium ions and a binder. A non-aqueous electrolyte secondary battery having a negative electrode having a carbon particle layer provided on a current collector and a non-aqueous electrolyte, wherein the binder is a styrene-based thermoplastic elastomer. Electrode film for electrolyte secondary battery.
断強度が５０ｋｇｆ／ｃｍ2以上のスチレン系熱可塑性
エラストマーを用いることを特徴とする請求項１記載の
非水電解液二次電池用電極フィルム。2. The non-aqueous electrolyte secondary according to claim 1, wherein a styrene thermoplastic elastomer having a breaking elongation of 300% or more and a breaking strength of 50 kgf / cm 2 or more is used as the binder. Battery electrode film.
２ｍｇＣＨ3ＯＮａ／ｇ以上のスチレン系熱可塑性エラ
ストマーを用いることを特徴とする請求項１または２記
載の非水電解液二次電池用電極フィルム。3. The non-aqueous electrolyte secondary battery according to claim 1, wherein a styrene-based thermoplastic elastomer having an acid value modified with maleic anhydride of 2 mg CH 3 ONa / g or more is used as a binder. Electrode film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7248180A JPH0992288A (en) | 1995-09-26 | 1995-09-26 | Electrode film for nonaqueous electrolyte secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7248180A JPH0992288A (en) | 1995-09-26 | 1995-09-26 | Electrode film for nonaqueous electrolyte secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0992288A true JPH0992288A (en) | 1997-04-04 |
Family
ID=17174396
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7248180A Pending JPH0992288A (en) | 1995-09-26 | 1995-09-26 | Electrode film for nonaqueous electrolyte secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0992288A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0821225A1 (en) * | 1996-07-26 | 1998-01-28 | Saft | Method for characterizing electrode binders |
| US6225003B1 (en) | 1998-10-26 | 2001-05-01 | Mitsubishi Chemical Corporation | Electrode materials having an elastomer binder and associated electrochemical and fabrication process |
| JP2007173047A (en) * | 2005-12-22 | 2007-07-05 | Mitsui Chemicals Inc | Binder for secondary battery |
| KR20140124321A (en) * | 2013-04-16 | 2014-10-24 | 삼성에스디아이 주식회사 | Seaparator and lithium battery containing the separator |
| KR20140124322A (en) * | 2013-04-16 | 2014-10-24 | 삼성에스디아이 주식회사 | Seaparator and lithium battery containing the separator |
| WO2024204220A1 (en) * | 2023-03-31 | 2024-10-03 | 日本ゼオン株式会社 | Binder composition for non-aqueous secondary battery electrode, slurry composition for non-aqueous secondary battery electrode, electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
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|---|---|---|---|---|
| JPS63181258A (en) * | 1987-01-21 | 1988-07-26 | Asahi Chem Ind Co Ltd | Cell electrode |
| JPH0574461A (en) * | 1991-09-13 | 1993-03-26 | Asahi Chem Ind Co Ltd | Secondary battery negative electrode |
| JPH05226004A (en) * | 1991-09-13 | 1993-09-03 | Asahi Chem Ind Co Ltd | Secondary battery |
| JPH07161348A (en) * | 1993-12-09 | 1995-06-23 | Fuji Photo Film Co Ltd | Nonaqueous secondary battery |
| JPH0831408A (en) * | 1994-05-13 | 1996-02-02 | Matsushita Electric Ind Co Ltd | Positive electrode for non-aqueous electrolyte lithium secondary battery and manufacture thereof |
| JPH08213022A (en) * | 1995-02-09 | 1996-08-20 | Fuji Photo Film Co Ltd | Nonaqueous secondary battery |
| JPH08250123A (en) * | 1995-03-07 | 1996-09-27 | Japan Synthetic Rubber Co Ltd | Aqueous binder for forming battery electrode |
| JPH0987571A (en) * | 1995-09-25 | 1997-03-31 | Nippon Zeon Co Ltd | Organic-solvent-base binder composition, electrode, and cell |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63181258A (en) * | 1987-01-21 | 1988-07-26 | Asahi Chem Ind Co Ltd | Cell electrode |
| JPH0574461A (en) * | 1991-09-13 | 1993-03-26 | Asahi Chem Ind Co Ltd | Secondary battery negative electrode |
| JPH05226004A (en) * | 1991-09-13 | 1993-09-03 | Asahi Chem Ind Co Ltd | Secondary battery |
| JPH07161348A (en) * | 1993-12-09 | 1995-06-23 | Fuji Photo Film Co Ltd | Nonaqueous secondary battery |
| JPH0831408A (en) * | 1994-05-13 | 1996-02-02 | Matsushita Electric Ind Co Ltd | Positive electrode for non-aqueous electrolyte lithium secondary battery and manufacture thereof |
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| JPH0987571A (en) * | 1995-09-25 | 1997-03-31 | Nippon Zeon Co Ltd | Organic-solvent-base binder composition, electrode, and cell |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0821225A1 (en) * | 1996-07-26 | 1998-01-28 | Saft | Method for characterizing electrode binders |
| US6225003B1 (en) | 1998-10-26 | 2001-05-01 | Mitsubishi Chemical Corporation | Electrode materials having an elastomer binder and associated electrochemical and fabrication process |
| JP2007173047A (en) * | 2005-12-22 | 2007-07-05 | Mitsui Chemicals Inc | Binder for secondary battery |
| KR20140124321A (en) * | 2013-04-16 | 2014-10-24 | 삼성에스디아이 주식회사 | Seaparator and lithium battery containing the separator |
| KR20140124322A (en) * | 2013-04-16 | 2014-10-24 | 삼성에스디아이 주식회사 | Seaparator and lithium battery containing the separator |
| WO2024204220A1 (en) * | 2023-03-31 | 2024-10-03 | 日本ゼオン株式会社 | Binder composition for non-aqueous secondary battery electrode, slurry composition for non-aqueous secondary battery electrode, electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
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