CA1204154A - Electrically conductive plastic electrode having a porous surface - Google Patents

Electrically conductive plastic electrode having a porous surface

Info

Publication number
CA1204154A
CA1204154A CA000441756A CA441756A CA1204154A CA 1204154 A CA1204154 A CA 1204154A CA 000441756 A CA000441756 A CA 000441756A CA 441756 A CA441756 A CA 441756A CA 1204154 A CA1204154 A CA 1204154A
Authority
CA
Canada
Prior art keywords
electrode
electrically conductive
bromine
conductive plastic
porous
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.)
Expired
Application number
CA000441756A
Other languages
French (fr)
Inventor
Akihiko Hirota
Toshinobu Fujii
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Meidensha Corp
Original Assignee
Meidensha Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Meidensha Corp filed Critical Meidensha Corp
Application granted granted Critical
Publication of CA1204154A publication Critical patent/CA1204154A/en
Expired legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/86Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96Carbon-based electrodes
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/36Accumulators not provided for in groups H01M10/05-H01M10/34
    • H01M10/365Zinc-halogen accumulators
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/64Carriers or collectors
    • H01M4/66Selection of materials
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/64Carriers or collectors
    • H01M4/66Selection of materials
    • H01M4/663Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30Hydrogen technology
    • Y02E60/50Fuel cells

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Inert Electrodes (AREA)
  • Hybrid Cells (AREA)
  • Electrotherapy Devices (AREA)

Abstract

Abstract Described is an electrically conductive plastic elec-trode having a porous surface for a bromine side electrode of zinc-bromine secondary cell comprising an electrically conductive plastic electrode proper to the surface of which is affixed a porous sheet of an electrically conduct-ing material with or without the intermediary of an adhesive layer. The plastic electrode is capable of improving and stably maintaining the efficiency of the electro-chemical reaction of bromine.

Description

~2q3~LS4 Title of the Invention Electrically Conductive Plas~ic Electrode ha~:ing a porous surface Field of the Invention This invention relates to an electrically conductive carbon plastic electrode havin~ a porous sur-ace used in a bromine side electrode of z~nc~xom~ne seccndary cell stack battery to the surface of which a layer of electrically conductive porous material is formed for improving and maintaining an energy efficiency of the electro-chemical reaction of bromine in the cell.

Back~round of the Invention The electrode in an electric cell stack ba.tery is required in order to provide a site of the electro-chemical reaction and stably prosecute the reaction in the cell. The electrode so far used to this purpose for the ~inc-~ro7mine secondary cell stack battery may be classified into a metallic electrode made of metallic material, carbon elec-trode made of carbon itself and an electrically conductive plastic electrode made from a plastic material ~ixed and blended with an electrically conducting material, such as carbon powder for imparting electrical conduc~ivity to the resulting electrode.

The metallic material for the metallic electrode is limited to noble metals such as platinum in vie~ of the corrosive action of molecular hromine that is produced in 4~5~ -charging the cell. The noble metals are usually rather lo~ in electric resistance and excellent in coulomb efficiency while also providing an acceptable voltage efficiency during a discharge period and a prolonged useful discharge time. However, the noble metals are expensive and thus are not practically used as electrode material.
Carbon electrodes are less costly than the noble metals and hence used widely from dry cell electrodes to electrodes for plant-size electro-chemical reactions.
However, these carbon electrodes are generally poor in operational reliability because they are extremely low in mechanical strength and tend to crack under the effect of mechanical impacts. Moreover, carbon electrodes are generally porous and thus are not usable in a series stack of cells bipolar battery system i21 which the electrode itself is designed to play the role of a partition plate.
As to an electrically conductive plastic electrodes of bromine side electrode one must accept the consequence of lower voltage and ~oulomb efficiencies in view of higher electric resistance and lower reactivity wlth bromine active material, although they are fairly sufficient in mechanical strength.
One of the present inventors has devised a bromine side electrode material which is higher in energy efficiency and free from the above inconvenience of the prior-art electrically conductive plastic electrode(Japanese Patent Laid Open No. 57-1194633. However, the electrode material proposed in this elder zpplication in use of brom~ e side electrode is not comple~ely sufficient to overcome the ~26~4154 drawback as to long endurance life ti~e operational ener~y efficiency and costs. In shor-t, there is not known so far in the art an electrode material that shows a proven qualit~
when used in a bromine side electr~de of zinc-bromine secon-dar~ cell stack battery.
Summar~ of the Invention As a result of our repeated researches into bro-mine side electrode material that is durable and inexpensive and provides an improved energy efficiency, the present inventors have found that the voltage efficiency and the coulomb efficiency of the bromine side electrically con-ductive plastic electrode may be i~proved by providing a porous sheet of the electrically conductiYe material on the electrode surface, and also found that especially good re-sults may be attained by using a specific pore size and porosity for the electrically conductive sheet material.
The present invention is based on this finding.
According to an aspect of the invention there is provided a bromine side, electrically conductive plastic electrode for a zinc-bromine secondary cell stact battery, the electrode comprising: an electrode body comprised of an electrically conductive plastic material; a porous sheet made of a fabric of carbon fibers and treated for affording numerous small pores, the porous sheet ha~ing a pore side of from 3 to 700 nm and a porosity higher than 2.0 volume %; and an adhesive layer affixing the porous sheet to the surface of the electrode body.
Brief Description of the Drawings Figs. 1 through 3 are graphic charts sho~ing the effects of an electrically conductive plastic electrode having a P~ 3 -~2~4~L54 porous surface of the present invention.

Detailed Description of the Invention Polyolefin resins are pre~erred to use as base polymer o~ the electrode in that the material is not degraded on long contact period with molecular or ionized bromine.
Typical o~ the polyolefin resins are polyethylene resins, polypropy~ene resins, chlorinated polyethylene reslns and chloxinated polypropylene resins, these being used singly or in combination as mixture. Any other resin constituents that may be used in the electrically conductive plastic electrode composition may be added to the afore-mentioned polyolefin resins for realizing desired elec-trode properties insofar as these additional components do not detract fr~m the properties usually re~uired of the electrode material.
An electrically conductive plastic electrode may be usually prepared by heat press ~orming of a compound contained the electrically conductive materials and a base polymer of polyolefin resins selected from the aforementioned resins.
When polyethylene resin is used as base polymer by way of an example, 50 weight parts of carbon black are mixed with 100 weight parts of high density polyethylene (with density, higher than 0.94 g/cm3) to an electrode compound which is then formed in a press heated to approximately 180 to 200C to the ultimate electrically conductive plastic electrode.
The electrically conductive material provided as a sheet tO the electrically conductive electrode surface in accordance with the present invention is a felted, knit-ted .. .. . . .

~;204~
or woven fabric of elec-trically conductiye carbon ~ibers having numerous small pores. The carbon fibers are usually made from a polyacrylic fiber or pitch ~iber.
Carbon fibers per se are in the form o ~ibers, however, in view of formability, they are preferably in the form of a sheet when formed as layer on the electrically conductive electrode surface.
The carbon fiber sheet employed in the present invention has a pore size in the range from 3 to 700 nm and a porosity higher than approximately 2.0%. The electri-cally conductive porous sheet may also be prepared from a carbon fiber sheet having the small pores and the porosity defined above. The porosity is defined by the following formula.
. total pore~volume (ml/g) ~ sheet weight (g/m2 x 10 6 x 100 pO~Slty P = Sheet thicknesS (m) As a result of our researches, it has been found that a linear relation exists between this porosity and the mean discharge electric potential~
By way of testing, several sheets (supplied by Toyobo Co., Ltd. under trade marks KF-M302, KF-M303 and KF-M304) of the electrically conductive carbon fibre in the form of cloths having different value of porosity were affixed hy heat pressing to respective samples of the electri-cally conductive carbon plastic electrodes. These porous surface electrodes were immersed in an electrolyte contain-ing 0.4 to 1.0 mole of Br2 per liter Pg/`~`~ - 5 ~

~Z~ ;i4 corresponding to the values occurriny before the expir-ation of discharge and mean electric potential of electrode V20 at the bromine side in the course of the constant discharge current of 20 mA/cm2 was measured by using Ag - AgCl as reference electrode. The resul-ts are tabulated as follows.

Cloth Used KF-M302 KF-~13 KF-M303KF~M304 (trade mark) Porosi-ty . 0.0 3.2 7.2 13.7 0(%) mOtennetlaelctric 0.723 0~739 0.788 0.796 v~o Fig. 1 shows a straight line adapted by the least square method from a curve obtained from the above Table.
The relation between the two variables P and V20 is given by a formula V = 5.7 x 10 3 P + 0.73 (correlative coefficient r = 0.928).
On the other hand, electrically conductive sheets in the form of knitted fabric (trade marks KF-M202 and KF-M203, supplied by Toyobo Co., Ltd.) and cloths (trade marks XF-M302 and KF-M303, supplied by Toyobo Co~, ~td.) were treated for affording a porosity of approximately 14% and the resulting sheets were affixed by heat pressing to the electrically con-ductive plastic electrode test pieces to the electrically conductive plastic electrode having a porous surface sample A (KF-M303 cloths; and KF-M203 knitted). Similarly, electrically conductive carbon fibre sheets which had not undergone the porous treatment were affixed by heat press-ing to other electrically conductive plastic test pieces to the electrically conductive plastic electrode havin~ a nonporous surface sample B (KF-M302 cloths; and KF-M202 knitted). The electrically conductive plastic electrode Pg/~ - 6 -LS~ , samples C were not treated in this ma~ner. The discharge electric potential characteristics of the respective saIQples ~, B, C were measured at room temperature with us0 of an electrolyte of 3 moles of ZnBr2 ~ Br2 per liter and at the current density of 40 mA/cm2. The results a.re sho~n in Figs. 2 and 3 for knitted Eabric and cloths respectively.
These test results are indicative o~ the excellent pro-perties of the inventive electrode A.
In a further test, zinc-bromine secondary cell with current density of 40 mA/Cm2, charging state of 80%, and an electrode-to-electrode distance equal to 2mmr was used as a test cell in which.a conventional electrically conductive plastic electrode ~ was used as a negative electrode (zinc side electrode) and the inventive electrode A provided with a porous electrically conductive layer wi.th porposity of 14%, the electrode B with affixed non-porous electrically conductive carbon fibre s:~eet and the conventional electrically conductive plastic electrode C were al-ternately used as positive electrodes (bromine side electrodes), and the energy efficiency was measured for the respec-tive anodes~ It was found that the efficiency was 72% for electrode A, 64 for electrode B and 56% for electrode C.
From the foregoing it is appa~ent that the arrange-ment of the present invention enables the electric resistance of electrode to be reduced and the reaction area to be in-creased through the use of the electrically conductive porous sheets with variable porosity levels w~ereby the energy efficiency of the cell may be improved. In addition, electri-cally conductive plastic electrodes having a porous surface may be manufactured according to diffe~ent usage require-ments and by a process substantially similar to that of the conventional process.

Pg/~

~2~4~5~

The electrode surface may become homogeneous due to pressure heat bonding of the elect.ically conducti~e porous sheet on the electrically cond~ctive elec-~rode thus reducing fluctuations in electrode characteristics.
An adhesive layer may option~lly be provided when providing the electrically conductive porous sheek to the surface of the electrically conductive plastic electrode.
The adhesive need have at least some affinity with both the plastic electrode material and the electrically con-ductive sheet. In general, one may use dispersion of small particles of silver or electrically conductive carbon in a liquid thermoplastic resin such as polyolefin resin.
The electrically conductive plastic electrode having a porous surface obtained in the manner described ; in the foregoing may be used not only in a zinc-bromine secondary cell for lmproving and main~aining the energy efficiency of the electro-chemical reaction but as an electrode for a bipolar type cell stack secondary battery.

p~ - 8 -

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A bromine side, electrically conductive plastic electrode for a zinc-bromine secondary cell stack battery, said electrode comprising:
an electrode body comprised of an electrically conductive plastic material;
a porous sheet made of a fabric of carbon fibers and treated for affording numerous small pores, said porous sheet having a pore side of from 3 to 700 nm and a porosity higher than 2.0 volume %; and an adhesive layer affixing said porous sheet to the surface of said electrode body.
2. An electrode according to claim 1, wherein the adhesive layer is a bromine-durable adhesive layer.
CA000441756A 1982-11-24 1983-11-23 Electrically conductive plastic electrode having a porous surface Expired CA1204154A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP57-204460 1982-11-24
JP57204460A JPS5996662A (en) 1982-11-24 1982-11-24 Plastic electrodes for zinc-bromine batteries

Publications (1)

Publication Number Publication Date
CA1204154A true CA1204154A (en) 1986-05-06

Family

ID=16490896

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000441756A Expired CA1204154A (en) 1982-11-24 1983-11-23 Electrically conductive plastic electrode having a porous surface

Country Status (5)

Country Link
EP (1) EP0112068B1 (en)
JP (1) JPS5996662A (en)
AT (1) ATE25169T1 (en)
CA (1) CA1204154A (en)
DE (1) DE3369433D1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0711969B2 (en) * 1983-03-23 1995-02-08 東洋紡績株式会社 Metal-halogen secondary battery
JPS6145567A (en) * 1984-08-08 1986-03-05 Meidensha Electric Mfg Co Ltd Method for manufacturing porous carbon plastic electrodes
JPS6145572A (en) * 1984-08-08 1986-03-05 Meidensha Electric Mfg Co Ltd Method of operating zinc-bromine battery
JPS61158673A (en) * 1984-08-16 1986-07-18 Meidensha Electric Mfg Co Ltd Zinc-halogen battery with porous electrodes
JPS628469A (en) * 1985-07-04 1987-01-16 Meidensha Electric Mfg Co Ltd Rotary zinc-bromine cell
JPH01183065A (en) * 1988-01-11 1989-07-20 Meidensha Corp Metal halogen battery
CN113193158B (en) * 2021-04-23 2022-04-12 东南大学 Three-dimensional zinc composite negative electrode and preparation method and application thereof

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3719526A (en) * 1971-02-03 1973-03-06 Zito Co Rechargeable metal halide battery
US3811945A (en) * 1972-08-24 1974-05-21 Consiglio Nazionale Ricerche Electric battery
US3772085A (en) * 1971-11-18 1973-11-13 Occidental Energy Dev Co Method and apparatus for improving efficiency of high energy density batteries of metal-metal halide-halogen type by boundary layer
US4104197A (en) * 1975-12-17 1978-08-01 Licentia Patent-Verwaltungs-G.M.B.H. Method of making gas diffusion electrodes for electrochemical cells with acid electrolytes
US4064207A (en) * 1976-02-02 1977-12-20 United Technologies Corporation Fibrillar carbon fuel cell electrode substrates and method of manufacture
US4104447A (en) * 1977-09-26 1978-08-01 Eco-Control, Inc. Halogen complexing alkyl salts for use in halogen cells

Also Published As

Publication number Publication date
EP0112068B1 (en) 1987-01-21
EP0112068A1 (en) 1984-06-27
ATE25169T1 (en) 1987-02-15
DE3369433D1 (en) 1987-02-26
JPS5996662A (en) 1984-06-04

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Effective date: 20031123