JPH1197026A - Electrode for li cell - Google Patents
Electrode for li cellInfo
- Publication number
- JPH1197026A JPH1197026A JP9255091A JP25509197A JPH1197026A JP H1197026 A JPH1197026 A JP H1197026A JP 9255091 A JP9255091 A JP 9255091A JP 25509197 A JP25509197 A JP 25509197A JP H1197026 A JPH1197026 A JP H1197026A
- Authority
- JP
- Japan
- Prior art keywords
- binder
- electrode
- active material
- electrode active
- 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.)
- Withdrawn
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】本発明はＬｉ電池用電極に関
し、さらに詳しくは特定の結着剤を使用したＬｉ電池用
電極に関する。The present invention relates to an electrode for a Li battery, and more particularly to an electrode for a Li battery using a specific binder.
【０００２】[0002]
【従来の技術】近年、エネルギー問題を背景に従来の二
次電池（鉛電池、Ｎｉ／Ｃｄ電池等）よりも高いエネル
ギー密度を有するＬｉ二次電池が注目されており、国家
プロジェクトをはじめ各方面で鋭意研究が行われてい
る。このＬｉ二次電池の充放電を担う電極においては、
電極活物質として導電性高分子（ポリアニリン、ポリピ
ロール等）や無機系酸化物材料（コバルト酸リチウム、
マンガン酸リチウム等）及び炭素材料等が用いられてい
る。これらの電極材料は通常粉体として得られるため、
電極成形時には、集電体（基材）への担持と活物質粒子
相互の結着を強めるため、結着剤を添加する必要があ
る。従来、この種の結着剤には、力学的な柔軟性及び電
気化学的な安定性の観点からポリフッ化ビニリデン（Ｐ
ＶＤＦ）やポリテトラフルオロエチレン（ＰＴＦＥ）等
が用いられてきた。2. Description of the Related Art In recent years, attention has been paid to Li secondary batteries having a higher energy density than conventional secondary batteries (lead batteries, Ni / Cd batteries, etc.) due to the energy problem. Research is being conducted in earnest. In the electrode responsible for charging and discharging of this Li secondary battery,
Conductive polymers (polyaniline, polypyrrole, etc.) and inorganic oxide materials (lithium cobaltate,
Lithium manganate, etc.) and carbon materials. Since these electrode materials are usually obtained as powder,
At the time of electrode molding, it is necessary to add a binder in order to strengthen the support on the current collector (base material) and the binding between the active material particles. Conventionally, this kind of binder includes polyvinylidene fluoride (P) in view of mechanical flexibility and electrochemical stability.
VDF), polytetrafluoroethylene (PTFE) and the like have been used.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、前記の
従来用いられている結着剤は以下のような問題点を有し
ている。 結着剤に電子伝導性及びイオン伝導性がほとんど無
いため、結着剤が電極活物質の酸化還元反応を阻害す
る。そのため、電極の本来有する充放電性能を引き出し
にくい。 結着剤に用いられるフッ素系高分子材料は、電解液
（又は有機溶媒）との親和性が低い。このため、Ｌｉ二
次電池等の電気化学セル製造時に電極内の微細な空孔へ
の電解液の浸透が困難になり、電極活物質の利用率の低
下をもたらす。 特にＰＴＦＥの場合には、可溶な溶媒が無いことか
ら、加熱溶融等の手法により成膜する必要があり、導電
性高分子等の有機材料を用いた電極の結着剤として使用
することはできない。また、加熱溶融法は溶媒キャスト
法に比べて大面積成膜には不向きである。 ＰＶＤＦ、ＰＴＦＥ共に汎用高分子材料としては比
較的高価である。However, the above-mentioned conventional binders have the following problems. Since the binder has little electron conductivity and ionic conductivity, the binder inhibits the oxidation-reduction reaction of the electrode active material. Therefore, it is difficult to draw out the charge / discharge performance inherent in the electrode. The fluorine-based polymer material used for the binder has a low affinity for an electrolytic solution (or an organic solvent). For this reason, it becomes difficult for the electrolyte solution to penetrate into the fine pores in the electrode at the time of producing an electrochemical cell such as a Li secondary battery or the like, and the utilization rate of the electrode active material is reduced. In particular, in the case of PTFE, since there is no soluble solvent, it is necessary to form a film by a method such as heating and melting, and it is not possible to use it as a binder for an electrode using an organic material such as a conductive polymer. Can not. Further, the heat melting method is not suitable for forming a large area film as compared with the solvent casting method. Both PVDF and PTFE are relatively expensive as general-purpose polymer materials.
【０００４】本発明は前記従来技術における問題点を解
決し、電極活物質の有効利用率が向上し、Ｌｉ電池（一
次電池及び二次電池）に適用した際の充放電性能が改善
されたＬｉ電池用電極を提供することを目的とする。The present invention solves the above-mentioned problems of the prior art, improves the effective utilization rate of the electrode active material, and improves the charge / discharge performance when applied to Li batteries (primary batteries and secondary batteries). An object is to provide an electrode for a battery.
【０００５】[0005]
【課題を解決するための手段】本発明は前記課題を解決
する手段として次の（１）〜（４）の構成を有する。 （１）粉末状又は粒状の電極活物質を集電体に結着させ
た電極であって、非水電解液及び導電性粉末を含み、平
均分子量６０〜６００の１分子当たり２個以上の水酸基
を有するポリオール化合物をイソシアネート化合物によ
り架橋反応させたゴム状結着剤により、前記電極活物質
どうし及び該電極活物質と集電体とを結着させてなるこ
とを特徴とするＬｉ電池用電極。The present invention has the following constitutions (1) to (4) as means for solving the above-mentioned problems. (1) An electrode in which a powdery or granular electrode active material is bound to a current collector, comprising a non-aqueous electrolyte and a conductive powder, and having two or more hydroxyl groups per molecule having an average molecular weight of 60 to 600. An electrode for a Li battery, wherein the electrode active materials are bound to each other and the current collector with a rubber-like binder obtained by subjecting a polyol compound having the following to a crosslinking reaction with an isocyanate compound.
【０００６】（２）非水電解液がリチウム塩を溶解させ
た有機溶剤であることを特徴とする前記（１）のＬｉ電
池用電極。 （３）導電性粉末が炭素粉末及び／又は金属粉末である
ことを特徴とする前記（１）又は（２）のＬｉ電池用電
極。 （４）電極活物質が導電性高分子であることを特徴とす
る前記（１）〜（３）のいずれか１つのＬｉ電池用電
極。(2) The electrode for a Li battery according to the above (1), wherein the non-aqueous electrolyte is an organic solvent in which a lithium salt is dissolved. (3) The electrode for a Li battery according to the above (1) or (2), wherein the conductive powder is a carbon powder and / or a metal powder. (4) The electrode for a Li battery according to any one of the above (1) to (3), wherein the electrode active material is a conductive polymer.
【０００７】本発明のＬｉ電池用電極は、分子レベルで
混合した状態で、三次元網目構造を持つ高分子（以下、
架橋高分子と称する）中に導電性粉末と電解質を分散・
溶解させた有機溶媒からなる非水電解液（以下、結着剤
電解液と称する）を含む粘着性ゴム状化合物からなる組
成物を結着剤として、電極活物質どうし及び該電極活物
質と集電体とを結着させてなることを特徴としている。
ここで架橋高分子は、結着剤電解液を安定保持する機能
を有するものである。また、架橋高分子と結着剤電解液
の分子レベルでの混合は、架橋高分子の原料（以下、マ
トリクス材料と称する）と結着剤電解液を混合した溶液
状態で架橋させることにより可能である。マトリクス材
料には電解液と相溶性のある材料を用いるため結着剤と
電解液との親和性がよく、電極活物質の利用率が向上す
る。更にマトリクス材料に汎用高分子材料であるポリエ
チレングリコール（ＰＥＧ）を用いることにより結着剤
のコストを下げることができる。本発明のＬｉ電池用電
極に使用する結着剤組成物において、結着剤電解液はイ
オン伝導性を担い、導電性粉末は電子伝導性を担うもの
である。それらの効果によって、本発明に係る結着剤組
成物は従来結着剤として使用されている材料と同様の結
着機能を有するほか、従来の材料にはないイオン伝導性
及び電子伝導性を有するものとなっている。[0007] The electrode for a Li battery of the present invention is a polymer having a three-dimensional network structure (hereinafter, referred to as "mixed") at a molecular level.
Conductive powder and electrolyte dispersed in a cross-linked polymer)
A composition comprising an adhesive rubber-like compound containing a non-aqueous electrolyte solution containing a dissolved organic solvent (hereinafter referred to as a binder electrolyte solution) is used as a binder to collect electrode active materials and collect the electrode active material. It is characterized by being bonded to an electric body.
Here, the crosslinked polymer has a function of stably holding the binder electrolyte. In addition, mixing of the crosslinked polymer and the binder electrolyte at the molecular level can be performed by crosslinking in a solution state in which a raw material (hereinafter, referred to as a matrix material) of the crosslinked polymer and the binder electrolyte are mixed. is there. Since a material compatible with the electrolytic solution is used as the matrix material, the affinity between the binder and the electrolytic solution is good, and the utilization rate of the electrode active material is improved. Further, by using polyethylene glycol (PEG) which is a general-purpose polymer material for the matrix material, the cost of the binder can be reduced. In the binder composition used for the electrode for a Li battery of the present invention, the binder electrolyte is responsible for ionic conductivity, and the conductive powder is responsible for electron conductivity. Due to these effects, the binder composition according to the present invention has a binding function similar to that of a material conventionally used as a binder, and has ionic conductivity and electronic conductivity that are not present in conventional materials. It has become something.
【０００８】[0008]
【発明の実施の形態】以下、リチウム二次電池の場合を
例にとって、本発明の実施の形態を説明する。本発明の
電極を構成する粉末状あるいは粒状の電極活物質として
は、正極活物質としてはポリアニリンなどの導電性高分
子、ＬｉＣｏＯ2 やＬｉＭｎＯ2 のような遷移金属系Ｌ
ｉ酸化物、負極活物質としてグラファイトなどの炭素材
料を例示することができる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below by taking a lithium secondary battery as an example. Examples of the powdery or granular electrode active material constituting the electrode of the present invention include a conductive polymer such as polyaniline as a positive electrode active material, and a transition metal based L such as LiCoO 2 or LiMnO 2.
Examples of the i-oxide and the negative electrode active material include carbon materials such as graphite.
【０００９】正極活物質である導電性高分子としては、
公知の方法によって製造されるポリアニリン、ポリピロ
ール、ポリチオフェンなどが使用できるが、中でも特開
平７−１７９５７８号公報に開示されている１分子中に
スルホン酸基を１個もしくは２個有するアニオン性低分
子量化合物であるアルキルスルホン酸を均一に等電荷量
だけドーピングさせた導電性高分子が好適である。As the conductive polymer which is a positive electrode active material,
Polyaniline, polypyrrole, polythiophene and the like produced by a known method can be used. Among them, an anionic low molecular weight compound having one or two sulfonic acid groups in one molecule disclosed in JP-A-7-179578 can be used. It is preferable to use a conductive polymer obtained by uniformly doping an alkyl sulfonic acid as described above with an equal charge amount.
【００１０】本発明に係る結着剤組成物における架橋高
分子は、マトリクス材料である平均分子量６０〜６００
の１分子当たり２個以上の水酸基を有するポリオール化
合物とイソシアネート化合物とを架橋反応させることに
よって形成される。マトリクス材料に架橋反応を行わせ
る方法としては、分子構造の末端にＯＨ基を２個以上有
するエチレングリコールやジエチレングリコールのよう
な低分子又はポリエチレングリコールやポリプロピレン
グリコールのような高分子のポリオールとイソシアネー
ト化合物の熱架橋反応（ウレタン生成反応）を用いるこ
とができる。この場合、マトリクス材料の分子量が低い
程イソシアネートとの反応性が高く、硬化は短時間で済
む。しかしながら、低分子量にすると分子構造上の架橋
点密度が増加するため、硬化に伴う体積変化（収縮）と
イオン伝導性の低下が起こる。従って、過度に低分子量
の材料を用いることは好ましくない。逆に、分子量が高
くなる程、架橋点密度が減少するためイオン伝導性は向
上するが、硬化に長時間を要する。以上の兼ね合いから
マトリクス材料の平均分子量は２００〜６００程度が好
ましい。The crosslinked polymer in the binder composition according to the present invention is a matrix material having an average molecular weight of 60 to 600.
Is formed by a crosslinking reaction between a polyol compound having two or more hydroxyl groups per molecule and an isocyanate compound. As a method of causing the matrix material to perform a crosslinking reaction, a low molecular weight such as ethylene glycol or diethylene glycol having two or more OH groups at the terminal of the molecular structure or a high molecular weight polyol such as polyethylene glycol or polypropylene glycol and an isocyanate compound are used. A thermal crosslinking reaction (urethane-forming reaction) can be used. In this case, the lower the molecular weight of the matrix material, the higher the reactivity with the isocyanate, and the shorter the curing time. However, when the molecular weight is reduced, the density of cross-linking points on the molecular structure increases, so that a volume change (shrinkage) due to curing and a decrease in ion conductivity occur. Therefore, it is not preferable to use a material having an excessively low molecular weight. Conversely, the higher the molecular weight, the lower the crosslinking point density and the higher the ionic conductivity, but the longer the curing time. From the above balance, the average molecular weight of the matrix material is preferably about 200 to 600.
【００１１】結着剤電解液として用いる有機溶媒の例と
しては、炭酸エチレン、γ−ブチロラクトン等の環状エ
ステル類、ジメチルホルムアミド、ジメトキシエタン、
ジエチルカーボネート等があり、これらの溶媒単独もし
くは複数の混合溶液を用いることが可能である。ただ
し、電解液の電気化学的安定性及び後述する電解質の溶
解性の点から少なくとも誘電率の高い（比誘電率３９以
上）環状エステル類を主溶媒とすることが好ましい。Examples of the organic solvent used as the binder electrolyte include cyclic esters such as ethylene carbonate and γ-butyrolactone, dimethylformamide, dimethoxyethane, and the like.
There are diethyl carbonate and the like, and a single solution or a mixed solution of a plurality of these solvents can be used. However, in view of the electrochemical stability of the electrolytic solution and the solubility of the electrolyte described later, it is preferable to use a cyclic ester having at least a high dielectric constant (relative dielectric constant of 39 or more) as the main solvent.
【００１２】前記有機溶媒中に分散・溶解させる電解質
は、リチウム二次電池においては、通常、リチウム塩が
使用される。リチウム塩の例としては、過塩素酸リチウ
ム（ＬｉＣｌＯ4 ）、四フッ化ホウ素酸リチウム（Ｌｉ
ＢＦ4 ）、六フッ化リン酸リチウム（ＬｉＰＦ6 ）、チ
オシアン酸リチウム（ＬｉＳＣＮ）、トリフルオロメタ
ンスルホン酸リチウム（ＬｉＣＦ3 ＳＯ3 ）等が挙げら
れるが、前記有機溶媒に溶解してＬｉイオンと対アニオ
ンに解離するものであれば、原理的にどのようなリチウ
ム塩であってもよい。As the electrolyte to be dispersed and dissolved in the organic solvent, a lithium salt is usually used in a lithium secondary battery. Examples of lithium salts include lithium perchlorate (LiClO 4 ) and lithium tetrafluoroboronate (Li
BF 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium thiocyanate (LiSCN), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), and the like. In principle, any lithium salt may be used as long as it dissociates into anions.
【００１３】しかしながら、結着剤電解液組成（溶媒
種、リチウム塩種及び濃度）がＬｉ電池全体（正極−負
極間）の電解液の組成と異なると、浸透圧の不一致によ
る結着剤の膨潤収縮が起こり、電極活物質の集電体から
の剥離が起こるおそれがある。このため、結着剤に含ま
れる電解液の組成は、Ｌｉ電池全体の電解液と同一であ
る必要がある。また、電解液中におけるリチウム塩の濃
度は、伝導度の観点から通常０．５〜２モル／リットル
程度に調製されており、本発明に係る結着剤組成物中の
結着剤電解液におけるリチウム塩濃度もその範囲とする
のが好ましい。However, if the composition of the binder electrolyte (solvent type, lithium salt type and concentration) is different from that of the entire Li battery (between the positive electrode and the negative electrode), the swelling of the binder due to the osmotic pressure mismatch will occur. Shrinkage may occur, and the electrode active material may be separated from the current collector. For this reason, the composition of the electrolyte contained in the binder needs to be the same as the electrolyte of the whole Li battery. In addition, the concentration of the lithium salt in the electrolyte is usually adjusted to about 0.5 to 2 mol / L from the viewpoint of conductivity, and the concentration of the lithium salt in the binder electrolyte in the binder composition according to the present invention is adjusted. It is preferable that the lithium salt concentration is also in the range.
【００１４】結着剤組成物中の電解液分率は結着剤のイ
オン伝導性に大きく影響し、電解液分率が高くなるほ
ど、結着剤のイオン伝導性は増大する。しかしながら、
電解液分率が過度に高くなると、結着剤全体の力学的強
度が低下し、電極材料の安定担持ができなくなる。ま
た、マトリクスポリマーの硬化に長時間を要する。した
がって、結着剤組成物中の電解液分率は、全結着剤組成
物重量に対して６０〜７０ｗｔ％にすることが好まし
い。The electrolytic solution fraction in the binder composition greatly affects the ionic conductivity of the binder, and the higher the electrolytic solution fraction, the higher the ionic conductivity of the binder. However,
When the electrolytic solution fraction is excessively high, the mechanical strength of the entire binder decreases, and the electrode material cannot be stably supported. Further, it takes a long time to cure the matrix polymer. Therefore, it is preferable that the electrolytic solution fraction in the binder composition is 60 to 70 wt% based on the total weight of the binder composition.
【００１５】結着剤組成物中に添加する導電性粉末とし
ては、アセチレンブラックや黒鉛粉末等の炭素粉末類や
Ａｌ粉末等の金属微粉末も原理的に使用可能である。た
だし、金属微粉末を用いる場合には、電気化学的安定性
を考慮する必要があり、電極活物質材料の酸化還元（充
放電）電位範囲内で溶解せず安定である材料が好まし
い。結着剤電解液中の導電性粉末が多いほど、電子伝導
性は向上するが、過度に添加量を増すと導電性粉末の嵩
高い性質により溶液がゲル化し、十分な均一混合ができ
なくなるため、導電性粉末の添加量は結着剤組成物全体
に対して３〜７ｗｔ％とするのが好ましく、より好まし
くは５ｗｔ％程度である。なお、電極活物質が炭素材料
である陰極の場合には、活物質である炭素材料が導電性
粉末の役割を兼ねるので特に導電性粉末を添加する必要
はない。As the conductive powder to be added to the binder composition, carbon powders such as acetylene black and graphite powder and fine metal powders such as Al powder can be used in principle. However, when metal fine powder is used, it is necessary to consider electrochemical stability, and a material that is stable without being dissolved within the oxidation-reduction (charge / discharge) potential range of the electrode active material is preferable. As the amount of the conductive powder in the binder electrolyte increases, the electron conductivity improves, but if the amount is excessively increased, the solution gels due to the bulky nature of the conductive powder, and sufficient uniform mixing cannot be performed. The amount of the conductive powder to be added is preferably 3 to 7% by weight, more preferably about 5% by weight, based on the whole binder composition. In the case where the electrode active material is a cathode made of a carbon material, it is not particularly necessary to add a conductive powder since the carbon material serving as the active material also serves as a conductive powder.
【００１６】本発明のＬｉ電池用電極を製造する一般的
な手法は次のとおりである。電極活物質と結着剤組成物
との配合割合は、用いる電極活物質材料の種類と必要と
される力学的強度によって異なるが、通常は、結着剤と
電極活物質との合計量に対して結着剤が１０〜５０ｗｔ
％程度とするのが好ましい。本発明に係る結着剤は、ポ
リオールの水酸基とイソシアネート化合物のイソシアネ
ート基との付加反応により硬化するため、電極活物質と
混合、成膜後、加熱により反応を促進させる必要があ
る。加熱温度は６０〜８０℃前後の比較的温和な条件と
するのが好ましい。加熱温度が高くなると、硬化に要す
る時間は短縮されるが、ポリオール材料の熱分解や結着
剤電解液中の溶媒の揮発が著しくなる。過度の電解液溶
媒の揮発は、硬化後の結着剤のイオン伝導性を低下させ
る要因となるので好ましくない。また、逆に加熱温度が
低すぎると硬化に長時間を要し、製造工程上効率的でな
い。A general method for producing the electrode for a Li battery of the present invention is as follows. The mixing ratio of the electrode active material and the binder composition varies depending on the type of the electrode active material used and the required mechanical strength, but is usually based on the total amount of the binder and the electrode active material. 10-50 wt binder
% Is preferable. Since the binder according to the present invention is cured by an addition reaction between the hydroxyl group of the polyol and the isocyanate group of the isocyanate compound, it is necessary to promote the reaction by heating after mixing with the electrode active material and forming a film. The heating temperature is preferably set to a relatively mild condition of about 60 to 80 ° C. When the heating temperature is increased, the time required for curing is reduced, but the thermal decomposition of the polyol material and the volatilization of the solvent in the binder electrolyte become significant. Excessive volatilization of the electrolyte solvent is not preferable because it causes a decrease in the ionic conductivity of the binder after curing. On the other hand, if the heating temperature is too low, it takes a long time for curing, which is not efficient in the production process.
【００１７】また、加熱時の雰囲気に水分が混入してい
ると、水分子とイソシアネート基の反応により炭酸ガス
が発生し、結着剤中における気泡発生により、硬化後の
結着剤の電極活物質の結着性や電気的特性（イオン伝導
性及び電子伝導性）の低下をもたらす。したがって、加
熱時の環境は乾燥空気とするか、窒素、アルゴン等の不
活性ガス雰囲気下で行うことが好ましい。If water is mixed in the atmosphere at the time of heating, a reaction between water molecules and isocyanate groups generates carbon dioxide gas, and bubbles are generated in the binder, so that the electrode activity of the cured binder is reduced. This leads to a decrease in the binding properties and electrical properties (ionic conductivity and electronic conductivity) of the substance. Therefore, it is preferable that the heating is performed in dry air or in an atmosphere of an inert gas such as nitrogen or argon.
【００１８】結着剤の硬化の判断は、巨視的には結着剤
電解液の流動性がなくなったことで判断し得るが、より
詳細には結着剤溶液に針状若しくは板状の微小な２電極
を挿入し、電極間に微細な交流振幅（１０〜１００ｍＶ
程度）を印加して、電極間のインピーダンス特性の時間
変化を追跡することで硬化状態を監視することができ
る。すなわち、結着剤中の電解液に溶解しているイオン
は、硬化による架橋構造の形成にともなってその運動を
阻害される。これは結着剤溶液のイオン伝導性の低下と
して現れ、電極間のインピーダンスを増加させる。イン
ピーダンス特性が一定となった時点（約２〜３％／ｈに
なった時点）で架橋反応が終了したと判断できる。The hardening of the binder can be determined macroscopically by the loss of the fluidity of the binder electrolyte. More specifically, the needle solution or the plate-like minute Two electrodes are inserted, and a fine AC amplitude (10 to 100 mV) is applied between the electrodes.
The degree of curing can be monitored by applying a degree of change and tracking the change over time of the impedance characteristic between the electrodes. That is, the movement of ions dissolved in the electrolyte solution in the binder is inhibited with the formation of a crosslinked structure by curing. This manifests itself as a decrease in the ionic conductivity of the binder solution, increasing the impedance between the electrodes. It can be determined that the cross-linking reaction has been completed when the impedance characteristic becomes constant (when the impedance characteristic becomes about 2-3% / h).
【００１９】[0019]
（１）結着剤溶液調製 平均分子量６００のポリエチレングリコール（ＰＥＧ）
６．０ｇと炭酸プロピレンとの混合物中に過塩素酸リチ
ウムを１モル／リットルの濃度となるように溶解させて
作製した電解液２４．４ｇを、結着剤溶液中の電解液が
７０ｗｔ％となるよう混合し、架橋剤として芳香族系イ
ソシアネート（ミリオネートＭＲ−３００、イソシアネ
ート基含有率３０％、日本ポリウレタン（株））２．８
ｇを混合した。架橋剤の添加量は、ＰＥＧのＯＨ基と架
橋剤の混合比が１：１となるように、次式に従ってＰＥ
Ｇ１ｇに対して０．４６７ｇの割合で添加した。 〔所要架橋剤量〕＝〔ＰＥＧのＯＨ基モル数〕×４２×１００／３０ ＝〔２×ＰＥＧ重量／６００〕×４２×１００／３０ ＝０．４６７×〔ＰＥＧ重量〕 更に導電助剤として、アセチレンブラック（デンカブラ
ック、電気化学工業）を１．７ｇ（５ｗｔ％）添加し
て、結着剤溶液を調製した。(1) Preparation of binder solution Polyethylene glycol (PEG) having an average molecular weight of 600
24.4 g of an electrolyte prepared by dissolving lithium perchlorate at a concentration of 1 mol / liter in a mixture of 6.0 g and propylene carbonate was added to a mixture containing 70 wt% of an electrolyte in a binder solution. And an aromatic isocyanate (Millionate MR-300, isocyanate group content 30%, Nippon Polyurethane Co., Ltd.) 2.8 as a crosslinking agent.
g were mixed. The amount of the cross-linking agent to be added is determined according to the following formula so that the mixing ratio between the OH group of the PEG and the cross-linking agent is 1: 1.
0.467 g was added to 1 g of G. [Required amount of crosslinking agent] = [molar number of OH groups of PEG] × 42 × 100/30 = [2 × PEG weight / 600] × 42 × 100/30 = 0.467 × [PEG weight] And 1.7 g (5 wt%) of acetylene black (Denka Black, Denki Kagaku Kogyo) were added to prepare a binder solution.
【００２０】（２）成膜・硬化 （１）により得られた溶液を口の字型のシリコンゴム
（内径 ３ｃｍ×３ｃｍ、厚さ０．５ｍｍ）を敷いたＰ
ＴＦＥ板上に流し込んだ後、別のＰＴＦＥ板で溶液を覆
い、大気圧窒素雰囲気下に８０℃で２４時間加熱して硬
化させた。(2) Film formation and curing The solution obtained in (1) was coated with a silicone rubber (inner diameter 3 cm × 3 cm, thickness 0.5 mm) spread over a mouth.
After pouring onto the TFE plate, the solution was covered with another PTFE plate and cured by heating at 80 ° C. for 24 hours under a nitrogen atmosphere at atmospheric pressure.
【００２１】（３）電子伝導性評価・イオン伝導性評価 得られた結着剤膜の電子伝導性及びイオン伝導性を評価
した。電子伝導性は、結着剤膜の両面をＳＵＳ電極で挟
んで１Ｖの電圧を印加し、十分時間が経過して電流が一
定となったときの電流値から導電率を測定した。また、
イオン伝導性の評価は、結着剤膜を上記同様ＳＵＳ電極
で挟んだ後、振幅１Ｖの正弦波信号を１０ＭＨｚから５
Ｈｚまで変化させながらインピーダンスを測定し、得ら
れた複素インピーダンスをＣｏｌｅ−Ｃｏｌｅプロット
により解析して求めた。電子伝導度、イオン伝導度はそ
れぞれ１Ｓ／ｃｍ、１×１０-3Ｓ／ｃｍであり、実用上
十分な伝導性を有していることが確認された。(3) Evaluation of electron conductivity / ion conductivity The obtained binder film was evaluated for electron conductivity and ionic conductivity. The electron conductivity was measured by applying a voltage of 1 V with both surfaces of the binder film sandwiched between SUS electrodes, and measuring the electric conductivity from the current value when a sufficient time passed and the current became constant. Also,
Evaluation of ionic conductivity was performed by sandwiching the binder film between SUS electrodes as described above, and then outputting a sinusoidal signal having an amplitude of 1 V from 10 MHz to 5 MHz.
The impedance was measured while changing the frequency up to Hz, and the obtained complex impedance was determined by analyzing the Cole-Cole plot. The electron conductivity and the ionic conductivity were 1 S / cm and 1 × 10 −3 S / cm, respectively, and it was confirmed that they had sufficient conductivity for practical use.
【００２２】（実施例２） 〔結着剤のＬｉ二次電池セルへの適用〕 （１）正極作製 化学酸化重合により合成したポリアニリン／エタンジス
ルホン酸複合体粉末（重量％でポリアニリン：６５．９
８％、エタンジスルホン酸：２４．６７％、水分：９．
３４％）２．１ｇをアセトンで希釈してアルミニウム箔
集電体（厚さ２５μｍ）上の１４ｃｍ×１０ｃｍの範囲
にコーティングした。真空乾燥によりアセトンを蒸発さ
せた後、実施例１と同一組成の結着剤溶液２．１ｇをロ
ールコータにより均一にポリアニリン／エタンジスルホ
ン酸複合体膜上に塗布した。結着剤のポリアニリン／エ
タンジスルホン酸複合体膜内への浸透性を改善するた
め、上記正極膜を室温下で減圧脱気した後、窒素雰囲気
下大気圧中で８０℃、２４時間加熱した。次に、実施例
１と同様に加熱してバインダーゲル溶液の硬化を行わせ
て、厚さ０．３ｍｍの正極膜を得た。また、比較のため
にＰＶＤＦ（Ｎ−メチルピロリドン溶液）を結着剤に用
いた同一組成の正極も作製した。(Example 2) [Application of binder to Li secondary battery cell] (1) Preparation of positive electrode Polyaniline / ethanedisulfonic acid composite powder synthesized by chemical oxidation polymerization (polyaniline in weight%: 65.9)
8%, ethanedisulfonic acid: 24.67%, moisture: 9.
(34%) 2.1 g was diluted with acetone and coated on a 14 cm × 10 cm area on an aluminum foil current collector (25 μm thick). After evaporating acetone by vacuum drying, 2.1 g of a binder solution having the same composition as in Example 1 was uniformly applied on the polyaniline / ethanedisulfonic acid composite membrane by a roll coater. In order to improve the permeability of the binder into the polyaniline / ethanedisulfonic acid composite membrane, the positive electrode membrane was degassed under reduced pressure at room temperature, and then heated at 80 ° C. for 24 hours in a nitrogen atmosphere at atmospheric pressure. Next, the binder gel solution was cured by heating in the same manner as in Example 1 to obtain a positive electrode film having a thickness of 0.3 mm. For comparison, a positive electrode having the same composition using PVDF (N-methylpyrrolidone solution) as a binder was also prepared.
【００２３】（２）セル組立 上記により作製した正極膜を図１に示す充放電試験セル
（ポリプロピレン製）内にセットした。ここで、図１
中、符号１０はセル、１１は正極、１２は負極、１３は
炭酸プロピレンに過塩素酸リチウム１ｍｏｌ／ｌ溶解し
てなる電解液、１４はＯリング、１５は外部端子（ＳＵ
Ｓ製）、１６は脱気口、１７は固定ボルト、１８は締結
手段をそれぞれ示す。図１に示すように、充放電セル１
０内に固定ボルト１７で正極１１をセットした後、負極
１２として７ｗｔ％Ａｌを添加したＬｉ／Ａｌ合金（３
ｃｍ×３ｃｍ×０．３ｍｍ）を固定ボルト１７によりセ
ットした。その後、セル１０を締結手段１８により密閉
し、脱気口１６から電解液１３をセル１０内に充填し
た。以上の工程は、Ｌｉの大気との接触による酸化を防
ぐため、アルゴン雰囲気にしたグローブボックス内で行
った。次に、組み上がったセル１０を室温条件下１Ｔｏ
ｒｒ以下の真空中で３時間脱気した。脱気によりセル外
へ漏れた電解液１３を脱気口１６から補充した後にセル
を密閉し、充放電試験に供した。(2) Cell Assembly The positive electrode film produced as described above was set in a charge / discharge test cell (made of polypropylene) shown in FIG. Here, FIG.
Reference numeral 10 denotes a cell, 11 denotes a positive electrode, 12 denotes a negative electrode, 13 denotes an electrolyte obtained by dissolving 1 mol / l of lithium perchlorate in propylene carbonate, 14 denotes an O-ring, and 15 denotes an external terminal (SU).
S), 16 is a deaeration port, 17 is a fixing bolt, and 18 is a fastening means. As shown in FIG.
After setting the positive electrode 11 with the fixing bolts 17 in the 0, the Li / Al alloy (3
cm × 3 cm × 0.3 mm) was set with the fixing bolt 17. Thereafter, the cell 10 was closed by the fastening means 18, and the electrolytic solution 13 was filled into the cell 10 through the deaeration port 16. The above steps were performed in a glove box in an argon atmosphere in order to prevent oxidation of Li due to contact with the atmosphere. Next, the assembled cell 10 is subjected to 1 To
Degassed for 3 hours in a vacuum below rr. After replenishing the electrolyte 13 leaked out of the cell by degassing from the degassing port 16, the cell was sealed and subjected to a charge / discharge test.
【００２４】（３）充放電試験 上記セルを端子間電圧２．５〜４．０Ｖの範囲で０．１
ｍＡ／ｃｍ2 の一定電流密度で充放電試験を行った。正
極活物質（ポリアニリン／エタンジスルホン酸複合体高
分子）当たりのエネルギー密度は、本発明に係る結着剤
及びＰＶＤＦを使用した場合でそれぞれ２０５Ｗ・ｈ／
ｋｇ、１５０Ｗ・ｈ／ｋｇであり、エネルギー密度の改
善が達成されており、電子、イオン混合伝導性結着剤を
使用することにより、正極活物質の利用率が増加してい
ることを確認できた。(3) Charging / discharging test The above cell was tested at a terminal voltage of 2.5 to 4.0 V in a range of 0.1 to 0.1.
A charge / discharge test was performed at a constant current density of mA / cm 2 . The energy density per positive electrode active material (polyaniline / ethanedisulfonic acid composite polymer) was 205 W · h / h when the binder according to the present invention and the PVDF were used.
kg, 150 W · h / kg, the improvement of energy density has been achieved, and it can be confirmed that the use rate of the positive electrode active material is increased by using the mixed conductive binder of electrons and ions. Was.
【００２５】[0025]
【発明の効果】本発明により、電極活物質の有効利用率
が向上し、充放電性能が改善されたエネルギー密度の高
いＬｉ二次電池を得ることができる。According to the present invention, it is possible to obtain a high energy density Li secondary battery in which the effective utilization rate of the electrode active material is improved and the charge / discharge performance is improved.
【図１】実施例２で使用した充放電試験セルの構造図。FIG. 1 is a structural diagram of a charge / discharge test cell used in Example 2.
Claims (4)
結着させた電極であって、非水電解液及び導電性粉末を
含み、平均分子量６０〜６００の１分子当たり２個以上
の水酸基を有するポリオール化合物をイソシアネート化
合物により架橋反応させたゴム状結着剤により、前記電
極活物質どうし及び該電極活物質と集電体とを結着させ
てなることを特徴とするＬｉ電池用電極。1. An electrode in which a powdered or granular electrode active material is bound to a current collector, comprising a non-aqueous electrolyte and a conductive powder, two or more per molecule having an average molecular weight of 60 to 600. For a Li battery, wherein the electrode active material is bound to each other and the electrode active material and a current collector by a rubbery binder obtained by subjecting a polyol compound having a hydroxyl group to a crosslinking reaction with an isocyanate compound. electrode.
機溶剤であることを特徴とする請求項１に記載のＬｉ電
池用電極。2. The electrode for a Li battery according to claim 1, wherein the non-aqueous electrolyte is an organic solvent in which a lithium salt is dissolved.
末であることを特徴とする請求項１又は２に記載のＬｉ
電池用電極。3. The Li according to claim 1, wherein the conductive powder is a carbon powder and / or a metal powder.
Electrodes for batteries.
特徴とする請求項１〜３のいずれか１項に記載のＬｉ電
池用電極。4. The electrode for a Li battery according to claim 1, wherein the electrode active material is a conductive polymer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9255091A JPH1197026A (en) | 1997-09-19 | 1997-09-19 | Electrode for li cell |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9255091A JPH1197026A (en) | 1997-09-19 | 1997-09-19 | Electrode for li cell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH1197026A true JPH1197026A (en) | 1999-04-09 |
Family
ID=17274005
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9255091A Withdrawn JPH1197026A (en) | 1997-09-19 | 1997-09-19 | Electrode for li cell |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH1197026A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006054779A1 (en) * | 2004-11-19 | 2006-05-26 | Fukoku Co., Ltd. | Charge storing rubber and electric double-layer capacitor, and lithium battery employing it |
| US7488557B2 (en) * | 2002-01-30 | 2009-02-10 | Panasonic Corporation | Electrode for lead-acid battery |
| WO2013172222A1 (en) * | 2012-05-14 | 2013-11-21 | 日東電工株式会社 | Electricity storage device, positive electrode and porous sheet used in electricity storage device, and method for improving dope rate |
| JP2013239306A (en) * | 2012-05-14 | 2013-11-28 | Nitto Denko Corp | Dual-mode type electricity storage device |
| JP2015501519A (en) * | 2011-10-28 | 2015-01-15 | ルブリゾル アドバンスド マテリアルズ， インコーポレイテッド | Electrode binder composition derived from polyurethane for electrochemical cells and electrode thereof |
| WO2020217730A1 (en) * | 2019-04-22 | 2020-10-29 | 第一工業製薬株式会社 | Binder composition for electrode, coating composition for electrode, electrode for power storage device, and power storage device |
-
1997
- 1997-09-19 JP JP9255091A patent/JPH1197026A/en not_active Withdrawn
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7488557B2 (en) * | 2002-01-30 | 2009-02-10 | Panasonic Corporation | Electrode for lead-acid battery |
| WO2006054779A1 (en) * | 2004-11-19 | 2006-05-26 | Fukoku Co., Ltd. | Charge storing rubber and electric double-layer capacitor, and lithium battery employing it |
| JP2015501519A (en) * | 2011-10-28 | 2015-01-15 | ルブリゾル アドバンスド マテリアルズ， インコーポレイテッド | Electrode binder composition derived from polyurethane for electrochemical cells and electrode thereof |
| WO2013172222A1 (en) * | 2012-05-14 | 2013-11-21 | 日東電工株式会社 | Electricity storage device, positive electrode and porous sheet used in electricity storage device, and method for improving dope rate |
| JP2013239306A (en) * | 2012-05-14 | 2013-11-28 | Nitto Denko Corp | Dual-mode type electricity storage device |
| JP2013239305A (en) * | 2012-05-14 | 2013-11-28 | Nitto Denko Corp | Electricity storage device, positive electrode used for the same, porous sheet, and method for improving doping ratio |
| WO2020217730A1 (en) * | 2019-04-22 | 2020-10-29 | 第一工業製薬株式会社 | Binder composition for electrode, coating composition for electrode, electrode for power storage device, and power storage device |
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