JPH031442A - Paste form cadmium negative electrode for alkaline storage battery - Google Patents
Paste form cadmium negative electrode for alkaline storage batteryInfo
- Publication number
- JPH031442A JPH031442A JP1137115A JP13711589A JPH031442A JP H031442 A JPH031442 A JP H031442A JP 1137115 A JP1137115 A JP 1137115A JP 13711589 A JP13711589 A JP 13711589A JP H031442 A JPH031442 A JP H031442A
- Authority
- JP
- Japan
- Prior art keywords
- polyvinyl alcohol
- cadmium
- electrode plate
- electrode
- cathode
- 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
- 229910052793 cadmium Inorganic materials 0.000 title claims abstract description 43
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 title claims description 43
- 238000003860 storage Methods 0.000 title claims description 6
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 51
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 51
- 229910052751 metal Inorganic materials 0.000 claims abstract description 20
- 239000002184 metal Substances 0.000 claims abstract description 20
- 239000011230 binding agent Substances 0.000 claims abstract description 12
- -1 polytetrafluoroethylene Polymers 0.000 claims abstract description 11
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims abstract description 11
- 239000004810 polytetrafluoroethylene Substances 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- PLLZRTNVEXYBNA-UHFFFAOYSA-L cadmium hydroxide Chemical compound [OH-].[OH-].[Cd+2] PLLZRTNVEXYBNA-UHFFFAOYSA-L 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- CXKCTMHTOKXKQT-UHFFFAOYSA-N cadmium oxide Inorganic materials [Cd]=O CXKCTMHTOKXKQT-UHFFFAOYSA-N 0.000 claims description 4
- CFEAAQFZALKQPA-UHFFFAOYSA-N cadmium(2+);oxygen(2-) Chemical compound [O-2].[Cd+2] CFEAAQFZALKQPA-UHFFFAOYSA-N 0.000 claims description 4
- 230000007423 decrease Effects 0.000 abstract description 14
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 abstract description 6
- 229910001882 dioxygen Inorganic materials 0.000 abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 abstract description 3
- 238000006116 polymerization reaction Methods 0.000 abstract description 2
- 238000007127 saponification reaction Methods 0.000 abstract description 2
- 239000013543 active substance Substances 0.000 abstract 2
- 238000007599 discharging Methods 0.000 abstract 2
- 230000001815 facial effect Effects 0.000 abstract 2
- 239000011149 active material Substances 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 12
- 238000000034 method Methods 0.000 description 10
- 238000001035 drying Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 239000000654 additive Substances 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 5
- 230000000996 additive effect Effects 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 230000002411 adverse Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 230000006911 nucleation Effects 0.000 description 3
- 238000010899 nucleation Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- IMROMDMJAWUWLK-UHFFFAOYSA-N Ethenol Chemical compound OC=C IMROMDMJAWUWLK-UHFFFAOYSA-N 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- OJIJEKBXJYRIBZ-UHFFFAOYSA-N cadmium nickel Chemical compound [Ni].[Cd] OJIJEKBXJYRIBZ-UHFFFAOYSA-N 0.000 description 1
- XIEPJMXMMWZAAV-UHFFFAOYSA-N cadmium nitrate Inorganic materials [Cd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XIEPJMXMMWZAAV-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000006232 furnace black Substances 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- NMHMNPHRMNGLLB-UHFFFAOYSA-N phloretic acid Chemical compound OC(=O)CCC1=CC=C(O)C=C1 NMHMNPHRMNGLLB-UHFFFAOYSA-N 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000012744 reinforcing agent Substances 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、アルカリ蓄電池等に用いられるペースト式カ
ドミウム陰極の改良に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to improvements in paste-type cadmium cathodes used in alkaline storage batteries and the like.
従来の技術
一般的にニッケルーカドミウム蓄電池等に用いられるカ
ドミウム陰極としては、多孔性ニッケル焼結基板に硝酸
カドミウムなどの所望活物質の塩溶液を含浸し、アルカ
リ液中で処理して該活物質塩を水酸化物に変化させるこ
とで活物質化するといった充填方法により製造される焼
結式カドミウム陰極と、活物質としての酸化カドミウム
や水酸化カドミウム、予備充電生成物マ
とヰしの金属カドミウム等を結着剤を用いてぺ／＼
一スト状に練合し、電極基板に塗着・乾燥して得られる
ペースト式カドミウム陰極がある。とくにペースト式カ
ドミウム陰極は、焼結式カドミウム陰極に比べて製造工
程が簡単であり、低コストでカドミウム陰極を作ること
ができるという利点がある。2. Description of the Related Art In general, a cadmium cathode used in nickel-cadmium storage batteries is made by impregnating a porous nickel sintered substrate with a salt solution of a desired active material such as cadmium nitrate, and treating it in an alkaline solution to remove the active material. A sintered cadmium cathode manufactured by a filling method in which salt is converted into an active material by converting it into hydroxide, cadmium oxide or hydroxide as an active material, and metallic cadmium as a pre-charge product matrix. There is a paste-type cadmium cathode that is obtained by kneading the mixture into a paste using a binder, applying it to an electrode substrate, and drying it. In particular, a paste type cadmium cathode has the advantage that the manufacturing process is simpler than a sintered type cadmium cathode, and the cadmium cathode can be manufactured at a lower cost.
しかしながらペースト式カドミウム陰極は、焼結式カド
ミウム陰極に比べると活物質の導電性が低いため過充電
時に陽極より発生する酸素ガスの吸収能力が低く、密閉
型電池にペースト式カドミウム陰極を用いると、電池缶
内圧が上昇しやすいという欠点を有している。However, paste-type cadmium cathodes have lower conductivity of the active material than sintered-type cadmium cathodes, and therefore have a lower ability to absorb oxygen gas generated from the anode during overcharging. This has the disadvantage that the internal pressure of the battery can tends to rise.
一方、焼結式カドミウム陰極は充放電サイクルを重ねて
いくと、活物質が不動態化し、放電不能の金属カドミウ
ムが蓄積し、極板容量が低下するという欠点を有してい
る。On the other hand, the sintered cadmium cathode has the disadvantage that, as charge and discharge cycles are repeated, the active material becomes passivated, metal cadmium that cannot be discharged accumulates, and the plate capacity decreases.
充放電サイクルの進行に伴なう容量低下の対策としては
、有機系添加物による方法が広くとられている。例えば
特開昭６３−１２１２５５号公報に記載されているよう
に、ポリビニルアルコールを添加することにより容量低
下を防止する方法がある。この場合は焼結式カドミウム
陰極ポリビニルアルコール水溶液を含浸した後、ポリビ
ニルアルコールの水溶液性を低下させるため熱処理を施
しており、ペースト式極板については本来導電性が低い
ため、未放電金属カドミウムの蓄積が生じる以前に他の
原因で寿命となるとし、その検討が加えられていない。As a countermeasure against capacity reduction as the charge/discharge cycle progresses, methods using organic additives are widely used. For example, as described in JP-A No. 63-121255, there is a method of preventing capacity reduction by adding polyvinyl alcohol. In this case, after the sintered cadmium cathode is impregnated with a polyvinyl alcohol aqueous solution, heat treatment is applied to reduce the aqueous properties of the polyvinyl alcohol, and since paste-type electrode plates inherently have low conductivity, undischarged metal cadmium accumulates. It is assumed that the lifespan will end due to other causes before this occurs, and this has not been considered.
発明が解決しようとする課題
前述のように、ペースト式カドミウム陰極の性能を向上
させるには、活物質の導電性の増加が必要となる。とこ
ろが、導電性が高まると充放電サイクルの進行に伴ない
不動態化した金属カドミウムの蓄積により極板容量の低
下を招くといった、従来焼結式陰極で大きな問題とされ
ていたことが重要な課題となる。Problems to be Solved by the Invention As mentioned above, improving the performance of paste-type cadmium cathodes requires increasing the electrical conductivity of the active material. However, as the conductivity increases, the accumulation of passivated metal cadmium as the charge/discharge cycle progresses, leading to a decrease in electrode plate capacity, which has been a major problem with conventional sintered cathodes. becomes.
では、ペースト式陰極であってもその導電性が向上すれ
ば、ポリビニルアルコールの如き添加物を利用すること
により、高導電性でサイクル特性のよいものが得られる
かということになるが、本発明者の検討によると実際に
導電性の向上したペースト式陰極性に先に示した方法を
適用しても、サイクル進行に伴う容量低下を防ぐことは
不可能である。なぜならば、含浸により極板内部にとり
込まれたポリビニルアルコール等の添加物は、金属カド
ミウムの不動態化を防ぐどころか、逆に活物質の導電性
を低下させるといった悪影響をもたらすからである。So, if the conductivity of a paste-type cathode can be improved, is it possible to obtain a cathode with high conductivity and good cycle characteristics by using additives such as polyvinyl alcohol? According to the research conducted by the authors, even if the method described above is applied to a paste-type cathode with improved conductivity, it is impossible to prevent the capacity from decreasing as the cycle progresses. This is because additives such as polyvinyl alcohol incorporated into the electrode plate through impregnation do not prevent passivation of metal cadmium, but instead have an adverse effect of reducing the conductivity of the active material.
本発明は、ポリビニルアルコールを添加物として用いた
際の悪影響をなくし、高導電性でしかも長期にわたって
極板容量の低下が小さいペースト式カドミウム陰極を提
供しようとするものである。The present invention aims to eliminate the adverse effects of using polyvinyl alcohol as an additive, and to provide a paste-type cadmium cathode that is highly conductive and exhibits a small decrease in plate capacity over a long period of time.
課題を解決するための手段
本発明のアルカリ蓄電池用ペースト式カドミウム陰極は
、カドミウム活物質とポリテトラフルオロエチレンを結
着剤として含み、がっ、極板表面にポリビニルアルコー
ルを含有するものである。Means for Solving the Problems The paste-type cadmium cathode for alkaline storage batteries of the present invention contains a cadmium active material and polytetrafluoroethylene as a binder, and also contains polyvinyl alcohol on the surface of the electrode plate.
ここで、カドミウム活物質は、酸化カドミウム、水酸化
カドミウム、金属カドミウムのいずれか一種以上から成
る。ただし、金属カドミウムを用いる場合は、その重量
は金属カドミウム以外のカドミウム活物質１００ｇに対
し、５〜３０ｇとするのが適当である。またポリテトラ
フルオロエチレンは、上記の１００ ｇに対して１〜８
ｇの重量とすれば、活物質の充填密度、利用率が向上す
る。この場合、ディスバージョンを用いることはまった
く問題なく、その粘度は１５〜２５ｃｐとするのが適当
である。Here, the cadmium active material is made of one or more of cadmium oxide, cadmium hydroxide, and metal cadmium. However, when metal cadmium is used, it is appropriate that its weight be 5 to 30 g per 100 g of cadmium active material other than metal cadmium. Moreover, polytetrafluoroethylene is 1 to 8 per 100 g of the above.
If the weight is 1.5 g, the packing density and utilization rate of the active material will be improved. In this case, there is no problem in using a dispersion, and the appropriate viscosity is 15 to 25 cp.
＾
ポリビニルアルコールは重合度５００〜３００，９．、
［囲で使用するのが望ましい。鹸化度は８０％以上が使
用に適し、８０〜９８％の部分鹸化物が物性上好ましい
が、９８％以上の完全鹸化物も用いることができる。水
溶液として用いる場合には、５〜１５重量％の濃度が適
当である。５％以下にすると溶液の粘度が低いため極板
内部へポリビニルアルコールが侵入する恐れがあり、１
５％以上では乾燥後ポリビニルアルコール皮膜の剥離が
見られ、良好な添加状態が得られない。ポリビニルアル
コールの添加は掻板の厚みの４分の１の深さまでが含有
の程度として適当であり、それ以上の添加は導電性の低
下を招く。^ Polyvinyl alcohol has a degree of polymerization of 500 to 300,9. ,
[It is preferable to use the A degree of saponification of 80% or more is suitable for use, and a partially saponified product of 80 to 98% is preferable in terms of physical properties, but a completely saponified product of 98% or more can also be used. When used as an aqueous solution, a concentration of 5 to 15% by weight is suitable. If it is less than 5%, the viscosity of the solution is low, so there is a risk of polyvinyl alcohol entering the inside of the electrode plate.
If it exceeds 5%, peeling of the polyvinyl alcohol film after drying is observed, and a good addition state cannot be obtained. It is appropriate to add polyvinyl alcohol to a depth of one-fourth of the thickness of the scraping plate, and addition beyond that will result in a decrease in conductivity.
またカーボンことビニルアルコールを表面に共存させる
ことにより、導電性や酸素ガス吸収性を向上させること
ができる。この場合、カーボンＭ１ｇに対してポリビニ
ルアルコールを０．１〜２ｇの範囲で調整することで種
々の添加方法に対応できる。カーボンの種類としては、
ファーネスブラック、アセチレンブラック、グラファイ
ト、活性炭等が適している。Furthermore, by coexisting carbon, also known as vinyl alcohol, on the surface, conductivity and oxygen gas absorbability can be improved. In this case, by adjusting the amount of polyvinyl alcohol in the range of 0.1 to 2 g per 1 g of carbon M, various methods of addition can be applied. The types of carbon are
Furnace black, acetylene black, graphite, activated carbon, etc. are suitable.
ポリビニルアルコールは一般に水溶性を示すため、極板
表面にポリビニルアルコールを含有させた後、ポリビニ
ルアルコールを架橋させ、電解液中への溶解を防止する
必要がある。ポリビニルアルコールの架橋方法としては
、ポリビニルアルコールを添加後、極板を１００°Ｃ以
上〜２００°Ｃ以下で乾燥処理することが好適である。Since polyvinyl alcohol generally exhibits water solubility, it is necessary to incorporate polyvinyl alcohol into the surface of the electrode plate and then crosslink the polyvinyl alcohol to prevent dissolution into the electrolytic solution. As a method for crosslinking polyvinyl alcohol, it is preferable to dry the electrode plate at a temperature of 100°C or more and 200°C or less after adding polyvinyl alcohol.
ため、電解液への溶解が防止でき、長期にわたって前記
効果を持続することが可能である。ただし、２００°Ｃ
以上になるとポリビニルアルコールは熱分解をおこすた
め、乾燥は１００°Ｃ以上２００石
°Ｃ以下の温度で按；なうことが必要である。さらに１
５０“０〜２００℃とすれば部分鹸化物で３０分〜１時
間、完全鹸化物で１分〜１０分の乾燥時間で十分である
。Therefore, dissolution in the electrolyte can be prevented, and the above effect can be maintained over a long period of time. However, 200°C
If the temperature is higher than that, polyvinyl alcohol will undergo thermal decomposition, so it is necessary to dry it at a temperature of 100°C or higher and 200°C or lower. 1 more
When the temperature is 0 to 200°C, a drying time of 30 minutes to 1 hour is sufficient for partially saponified products, and 1 minute to 10 minutes for completely saponified products.
作用
結着剤としてポリテトラフルオロエチレンを用いること
により、活物質充填密度および活物質利用率が向上し、
さらに導電性の増加に伴ない酸化ガス吸収性能も向上し
、極板性能は大きく改善される。しかし、極板の導電性
が柔りなると、充放電サイクルの進行に伴なう極板容量
の低下という新たな問題に直面する。By using polytetrafluoroethylene as a functional binder, the active material packing density and active material utilization rate are improved,
Furthermore, as the conductivity increases, the oxidizing gas absorption performance also improves, and the electrode plate performance is greatly improved. However, when the conductivity of the electrode plate becomes softer, a new problem arises: the plate capacity decreases as the charge/discharge cycle progresses.
前述のように、カドミウム極板は充放電サイクルを重ね
ることにより極板容量が低下する。As mentioned above, the capacitance of a cadmium plate decreases with repeated charge/discharge cycles.
これは放電時に金属カドミウムのまわりを放電生成物で
ある水酸化カドミウムがおおってしまい、金属カドミウ
ムと電解液と遮断され、内部の金属カドミウムが放電不
能となって残存し、蓄積していくことによるものである
。This is because cadmium hydroxide, which is a discharge product, covers the metal cadmium during discharge, and the metal cadmium and electrolyte are cut off, and the metal cadmium inside becomes unable to discharge and remains and accumulates. It is something.
ポリビニルアルコールが存在すると、放電時に起こる水
酸化カドミウムの金属カドミウム表面への核形成が抑え
られ、金属カドミウム表面が水酸化カドミウムの被膜で
おおわれ、内部の金属カドミウムが不動態化するのを防
止することが可能である。The presence of polyvinyl alcohol suppresses nucleation of cadmium hydroxide on the metal cadmium surface that occurs during discharge, and the metal cadmium surface is covered with a cadmium hydroxide film, preventing the metal cadmium inside from becoming passivated. is possible.
しかし、添加物としてポリビニルアルコールを用いる場
合は、その添加方法により効果は大きく異なる。即ち、
活物質の結着剤としてポリビニルアルコールを用いた場
合がそうであるように、ペースト内部にポリビニルアル
コールが存在する芒と、活物質の導電性を著しく阻害し
、結果としてはポリビニルアルコールの添加により極板
の性能を低下させることになる。これに対し、ポリビニ
ルアルコールを極板の表面近傍にのみ存在させると、ペ
ーストの導電性に悪影響を与えることなく、添加物とし
て効果を発揮させることができる。なぜならば、前述の
ように極板の容量低下は氷結化カドミウムの核形成が重
要な因子となっており、金属カドミウムの不動態化が水
酸化カドミウムの核形成の活発に行われる状況下、すな
わち電解液と接している極板表面近くで主として起こる
からである。このため、添加物としてのポリビニルアル
コールは極板表面近傍に存在するだけで十分であり、こ
の場所に存在している限りはペーストの導電性を低下さ
せることもないのである。However, when polyvinyl alcohol is used as an additive, the effects vary greatly depending on the method of addition. That is,
As is the case when polyvinyl alcohol is used as a binder for the active material, the presence of polyvinyl alcohol inside the paste will significantly inhibit the conductivity of the active material, and as a result, the addition of polyvinyl alcohol will cause polarization. This will reduce the performance of the board. On the other hand, when polyvinyl alcohol is present only near the surface of the electrode plate, it can be effective as an additive without adversely affecting the conductivity of the paste. This is because, as mentioned above, the nucleation of frozen cadmium is an important factor in reducing the capacity of the electrode plate, and the passivation of metallic cadmium occurs under conditions where the nucleation of cadmium hydroxide is active, i.e. This is because it mainly occurs near the surface of the electrode plate that is in contact with the electrolyte. Therefore, it is sufficient for polyvinyl alcohol as an additive to be present near the surface of the electrode plate, and as long as it is present at this location, it will not reduce the conductivity of the paste.
また、ポリビニルアルコールの役割としては、金属カド
ミウムが電解液と完全に遮断されるのを防ぐことで、こ
れには水酸化カドミウムの核の生成をある程度に抑える
ことが必要であるが、１００％阻止する必要はない。む
しろ少数の核が存在し、それらがある程度の大きさに成
長することにより、金属カドミウムをすき間なく覆うこ
とができなくなる状態が理想的である。それには、極板
表面をポリビニルアルコールで被ｆｆする必要はなく、
不均一に存在してもその効果は十分にある。In addition, the role of polyvinyl alcohol is to prevent metal cadmium from being completely isolated from the electrolyte, and this requires suppressing the generation of cadmium hydroxide nuclei to a certain extent, but 100% inhibition is required. do not have to. Rather, it is ideal that a small number of nuclei exist and that they grow to a certain size so that they cannot cover the metal cadmium without any gaps. For this purpose, there is no need to coat the surface of the electrode plate with polyvinyl alcohol.
Even if it exists unevenly, its effect is sufficient.
以上の方法で、ポリテトラフルオロエチレンの利用によ
り、利用率、導電性等の緒特性改善を果だ古すたに生じ
た極板容量低下の問題もポリビニルアルコールの最適な
添加方法を見い出すことにより解決することができる。By using the above method, the problem of decrease in electrode plate capacity that occurred even after improvement of initial properties such as utilization rate and conductivity by using polytetrafluoroethylene can be solved by finding the optimal method for adding polyvinyl alcohol. It can be solved.
実施例
実施例１
生活物質としての酸化カドミウム１００ｇに、金属カド
ミウム粉末２０ｇを混合し、この混合粉末に結着剤とし
てのポリテトラフルオロエチレン３ｇ、さらに補強剤と
してナイロン繊維、導電材としてグラファイトを一定量
加えた後、十分に混練してペースト状とし、導電芯体に
塗着・乾燥した。次いでこの極板表面上へ、カーボン粉
末とポリビニルアルコールを混練、塗着し、１２０°Ｃ
，１６０°Ｃ，２００°Ｃの温度で乾燥し、それぞれ本
発明陰極Ａ、Ｂ、Ｃを得た。Examples Example 1 100 g of cadmium oxide as a living material is mixed with 20 g of metal cadmium powder, and this mixed powder is mixed with 3 g of polytetrafluoroethylene as a binder, nylon fiber as a reinforcing agent, and graphite as a conductive material. After adding the amount, it was sufficiently kneaded to form a paste, which was applied to a conductive core and dried. Next, carbon powder and polyvinyl alcohol were kneaded and applied onto the surface of the electrode plate, and heated at 120°C.
, 160°C, and 200°C to obtain cathodes A, B, and C of the present invention, respectively.
実施例２
実施例１に示したものと同じペースト組成の極板表面に
、ポリビニルアルコールの８％水溶液を噴霧し、１６０
°Ｃの温度で乾燥して本発明陰極りを得た。Example 2 An 8% aqueous solution of polyvinyl alcohol was sprayed onto the surface of an electrode plate having the same paste composition as that shown in Example 1.
The cathode of the present invention was obtained by drying at a temperature of °C.
実施例３
実施例１に示したものと同じペースト組成の極板表面に
、Ｐ液なる懸濁液を噴霧し、１６０°Ｃの温度で乾燥し
て本発明陰極Ｅを得た。Example 3 A suspension called P solution was sprayed onto the surface of an electrode plate having the same paste composition as that shown in Example 1, and dried at a temperature of 160° C. to obtain a cathode E of the present invention.
ここでＰ液とは、ポリビニルアルコールの８％水溶液に
、ポリビニルアルコールに対する重量比で１：ｌに相当
する量のカーボン粉末を懸濁させたものである。Here, the P liquid is a suspension of carbon powder in an amount corresponding to a weight ratio of 1:1 to polyvinyl alcohol in an 8% aqueous solution of polyvinyl alcohol.
比較例１
実施例１において、その乾燥温度を２５°Ｃ１９０”Ｃ
，２２０’Ｃとし、それぞれ比較陰極Ｆ、ＧＪとした。Comparative Example 1 In Example 1, the drying temperature was changed to 25°C and 190"C.
, 220'C, and were used as comparison cathodes F and GJ, respectively.
比較例２
実施例１において、カーボン粉末とポリビニルアルコー
ルの混練・塗着以降の過程を行わなかったものを比較陰
極■とした。Comparative Example 2 Comparative cathode (2) was prepared in Example 1 without performing the steps after kneading and coating the carbon powder and polyvinyl alcohol.
比較例３
比較陰極ｉにおいて、その極板組成中、結着剤をポリテ
トラフルオロエチレンの代わりにポリビニルアルコール
とし、他はＩと同様に作成したものを比較陰極Ｊとした
。Comparative Example 3 Comparative cathode J was prepared in the same manner as in Comparative cathode I except that polyvinyl alcohol was used as the binder in place of polytetrafluoroethylene in the electrode plate composition.
比較例４
比較陰極Ｉにおいて、その表面にカーボン粉末ヲ塗着し
、次いで８％ポリビニルアルコール水溶液を含浸させた
後、１６０″Ｃの温度で乾燥して比較陰極にとした。Comparative Example 4 Carbon powder was coated on the surface of Comparative Cathode I, and then impregnated with 8% polyvinyl alcohol aqueous solution, and dried at a temperature of 160''C to obtain a comparative cathode.
上記陰極ＡないしＫをそれぞれ水酸化カリウム水溶液中
で白金網を対極として繰り返し充放電し、充放電サイク
ルの進行にともなう極板容量の変化を調べ、さらに焼結
式ニッケル陽極と組み合わせで密閉型電池を試作し、過
充電時の酸素ガス吸収能力について調べた。Each of the above cathodes A to K was repeatedly charged and discharged in an aqueous potassium hydroxide solution using a platinum wire mesh as a counter electrode, and the changes in electrode plate capacity as the charge and discharge cycles progressed were investigated. We made a prototype and investigated its ability to absorb oxygen gas during overcharging.
第１図にＡ、Ｅ、Ｆ、■、Ｊの極板容量変化の様子を示
す。また第２図にＡ、Ｊ、Ｋを陰極とした場合の電池の
内圧の変化の様子を示す。Figure 1 shows the changes in capacitance of the electrode plates A, E, F, ■, and J. Furthermore, FIG. 2 shows how the internal pressure of the battery changes when A, J, and K are used as cathodes.
これらの図よりわかるように、表面にポリビニルアルコ
ールが存在し１６０°Ｃの温度で乾燥した本発明陰極Ａ
、Ｅは、比較陰極Ｆ、■にくらべ、極板容量低下が少な
い。Ｆは極板表面にポリビニルアルコールが存在するも
のの、熱処理を行っていないためにポリビニルアルコー
ルが電解液中に溶出し、その効果が２０サイクル程度し
か持続しなかったものである。またＪは極板容量の低下
が少ないが、これは結着剤としてポリビニルアルコール
を用いているため活物質の導電性が低く、前記のような
金属カドミウムの不動態化がおこらなかったためである
。第２図は陰極の酸素ガス吸収性能を示すものであるが
、本発明陰極Ａはこの点でもすぐれている。比較陰極Ｊ
は極板容量の低下については問題はなかったが、第２図
で明らかなように、ポリビニルアルコールを結着剤とし
たためにガス吸収性能痘
が著しく劣っている。また比較種板Ｋについては、ポリ
テトラフルオロエチレンを用い、さらに極板表面にカー
ボンを有しているにもかかわらずガス吸収性能が低い。As can be seen from these figures, the cathode A of the present invention has polyvinyl alcohol on its surface and has been dried at a temperature of 160°C.
, E show less decrease in electrode plate capacity than comparative cathodes F and ①. In F, although polyvinyl alcohol was present on the surface of the electrode plate, the polyvinyl alcohol was eluted into the electrolyte because no heat treatment was performed, and the effect lasted only about 20 cycles. Further, in J, the decrease in electrode plate capacity was small, but this was because polyvinyl alcohol was used as a binder, so the conductivity of the active material was low, and the metal cadmium was not passivated as described above. FIG. 2 shows the oxygen gas absorption performance of the cathode, and the cathode A of the present invention is also excellent in this respect. Comparative cathode J
Although there was no problem with the decrease in electrode plate capacity, as is clear from FIG. 2, the gas absorption performance was significantly inferior due to the use of polyvinyl alcohol as a binder. Comparative seed plate K has low gas absorption performance despite using polytetrafluoroethylene and having carbon on the surface of the electrode plate.
これはポリビニルアルコールを添加する際、水液液に極
板を浸漬する方法をとっているため、ポリビニルアルコ
ールが極板表面近傍のみならず内部まで侵入してしまい
、活物質の導電性を低下させてしまったためである。This is because when adding polyvinyl alcohol, the electrode plate is immersed in an aqueous liquid, so the polyvinyl alcohol penetrates not only near the surface of the electrode plate but also inside, reducing the conductivity of the active material. This is because it happened.
第３図にポリビニルアルコールの乾燥温度と極板容量変
化の関係を示した。この図は陰極Ａ〜ＣおよびＦ−Ｈに
ついて、１サイクル目と３０サイクル目の容量比をプロ
ットしたものである。FIG. 3 shows the relationship between the drying temperature of polyvinyl alcohol and the change in electrode plate capacity. This figure plots the capacity ratios of the 1st cycle and the 30th cycle for cathodes A to C and FH.
この図からもわかるように、乾燥温度が１００°Ｃ〜２
００°Ｃのものは容量低下が少なく、この範囲外の温度
で乾燥すると長期にわたって容量低下を抑制することが
できなくなる。As you can see from this figure, the drying temperature is 100°C~2
If the temperature is 00°C, the capacity decrease is small, and if dried at a temperature outside this range, the capacity decrease cannot be suppressed for a long period of time.
発明の効果
本発明は、ペースト式陰極への添加物としてポリビニル
アルコールを検討する上で、ポリビニルアルコールが極
板へ悪影響を及ぼすことのない添加方法を適用し、結着
与ξ−ボンとの組み合わせの最適化を計ったものであり
、導電性、酸素ガス吸収性にすぐれ、充放電サイクルに
伴なう極板容量低下が少ないものである。Effects of the Invention The present invention, in considering polyvinyl alcohol as an additive to paste-type cathodes, applied an addition method in which polyvinyl alcohol does not have an adverse effect on the electrode plate, and combined it with a binding agent ξ-bon. It has excellent conductivity and oxygen gas absorption, and has little decrease in plate capacity due to charge/discharge cycles.
【図面の簡単な説明】
第１図は充放電サイクルと極板容量比の関係を示す図、
第２図は充放電時間と電池缶内圧の関係を示す図、第３
図はポリビニルアルコール乾燥温度と極板容量比の関係
を示す図である。
Ａ−Ｅ・・・本発明陰極[Brief explanation of the drawings] Figure 1 is a diagram showing the relationship between charge/discharge cycles and plate capacity ratio.
Figure 2 is a diagram showing the relationship between charge/discharge time and battery can internal pressure.
The figure is a diagram showing the relationship between polyvinyl alcohol drying temperature and electrode plate capacity ratio. A-E... Cathode of the present invention
Claims (2)
ウムの中から選んだ少なくとも１種と、結着剤としての
ポリテトラフルオロエチレンとをその成分に含み、極板
表面にポリビニルアルコールを含有することを特徴とす
るアルカリ蓄電池用ペースト式カドミウム陰極。(1) Features include at least one selected from metal cadmium, cadmium oxide, and cadmium hydroxide, and polytetrafluoroethylene as a binder, and polyvinyl alcohol on the surface of the electrode plate. Paste-type cadmium cathode for alkaline storage batteries.
ていることを特徴とする特許請求の範囲第１項記載のア
ルカリ蓄電池用ペースト式カドミウム陰極。(2) The paste-type cadmium cathode for an alkaline storage battery according to claim 1, characterized in that carbon and polyvinyl alcohol are mixed on the surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1137115A JPH031442A (en) | 1989-05-30 | 1989-05-30 | Paste form cadmium negative electrode for alkaline storage battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1137115A JPH031442A (en) | 1989-05-30 | 1989-05-30 | Paste form cadmium negative electrode for alkaline storage battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH031442A true JPH031442A (en) | 1991-01-08 |
Family
ID=15191183
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1137115A Pending JPH031442A (en) | 1989-05-30 | 1989-05-30 | Paste form cadmium negative electrode for alkaline storage battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH031442A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996030445A1 (en) * | 1995-03-31 | 1996-10-03 | Daikin Industries, Ltd. | Aqueous polytetrafluoroethylene dispersion composition and use thereof |
| KR100800969B1 (en) * | 2006-01-18 | 2008-02-11 | 주식회사 엘지화학 | Electrode Material Containing Polyvinyl Alcohol as Binder and Rechargeable Lithium Battery Comprising the Same |
| KR20160034063A (en) * | 2014-09-19 | 2016-03-29 | 김용운 | Kitchen appliance having measuring function |
-
1989
- 1989-05-30 JP JP1137115A patent/JPH031442A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996030445A1 (en) * | 1995-03-31 | 1996-10-03 | Daikin Industries, Ltd. | Aqueous polytetrafluoroethylene dispersion composition and use thereof |
| CN1125131C (en) * | 1995-03-31 | 2003-10-22 | 大金工业株式会社 | Aqueous polytetrafluoroethylene dispersion composition and use thereof |
| KR100800969B1 (en) * | 2006-01-18 | 2008-02-11 | 주식회사 엘지화학 | Electrode Material Containing Polyvinyl Alcohol as Binder and Rechargeable Lithium Battery Comprising the Same |
| KR20160034063A (en) * | 2014-09-19 | 2016-03-29 | 김용운 | Kitchen appliance having measuring function |
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