Cutlery
Patent
1995-05-02
1997-09-09
Bell, Bruce F.
Cutlery
204280, 204290R, 204291, 204286, 204294, 429 40, 429 42, 429191, 429192, 429212, 429213, 429218, 429232, 429233, 429241, 252500, 252502, 428408, C25D 1704
Patent
active
056652127
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention is directed to a flexible, conducting plastic electrode and a process for the preparation of the same. The electrodes have application in redox flow batteries, particularly vanadium redox flow batteries, as well as in other electrochemical applications such as electrodepositing and electrowinning.
BACKGROUND ART
The desired characteristics for electrode materials which are to be used in redox cells to and other electrolytic processes include: low electrical resistivity, good mechanical properties and chemical stability and optionally low weight and low volume. The electrode material should not be attacked by reactants or products during cell operation. Thus there is a need for an electrode material which has good mechanical properties to withstand the hydraulic pressure and cell assembling operation without cracking and which is solution impermeable so that penetration and attack of the metal current collector (in end-electrodes) and loss in current efficiency (due to electrolytes crossing the bipolar electrodes) is low.
OBJECTS OF THE INVENTION
Objects of the present invention are to provide a flexible, conducting plastic electrode and a process for the preparation of the same.
DISCLOSURE OF THE INVENTION
The present inventors have surprisingly found that by combining a thermo-plastic polymer, an elastomeric polymer and a conductive filler material, a superior flexible, conducting plastic electrode is produced which has good physical strength, chemical stability and electrical conductivity. In particular, the inventors have found that by combining, for example, high density polyethylene (HDPE) resin, an elastomeric polymer such as, for example, styrene-ethene/butene-styrene (SEBS) block copolymer and conductive filler material such as carbon black particles or a mixture of carbon black particles and graphite fibres, a commercially useable plastic electrode is produced.
According to a first embodiment of this invention there is provided a flexible, conducting plastic electrode comprising:
(a) a conductive filler material;
(b) a thermo-plastic polymer; and
(c) an elastomeric polymer at least partially cross-linked with (b); conducting and the degree of cross-linking of (b) with (c) is such that the electrode is flexible and has high tensile strength.
According to another embodiment of this invention there is provided a flexible, conducting plastic electrode comprising:
(a) a conductive filler material;
(b) a thermo-plastic polymer: and
(c) an elastomeric polymer; conducting and the amounts of (a):(b):(c) are such that the electrode is flexible and has high tensile strength.
The conducting plastic electrode of the first embodiment may be pressure and heat welded onto at least one metal mesh, a metal mesh and graphite felt or at least one graphite felt. Hence, in the case when the electrode is in the form of a sheet the following configurations may be employed, for example:
(1) a metal mesh may be pressure and heat welded onto at least one side of the sheet;
(2) a metal mesh may be pressure and heat welded onto one side of the sheet and a graphite felt pressure and heat welded onto the other side of the sheet;
(3) a graphite felt may be pressure and heat welded onto at least one side of the sheet; and
(4) a metal mesh sheet or foil may be pressure and heat welded between two of the flexible, conducting plastic electrodes.
Carbon and graphite felts are generally woven from yarns which are bundles of individual carbon monofilaments generally having a diameter in the range from about 1 to 50 .mu.m, usually in the range from about 5 to 10 .mu.m. The yarns will typically include from about 100 to 20,000 monofilaments, usually having from about 3,000 to 6,000 filaments. The denier of the yarns used as in fabricating the carbon felts will typically be in the range from about 500 to 5,000 mg/m, usually being in the range from about 1,000 to 2,000 mg/m. Denier is equal to the number of grams which yield 9,000 meters of the yarn or filament. The yarns are woven by convent
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patent: 4164068 (1979-08-01), Snropshire
patent: 4379814 (1983-04-01), Tsien et al.
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patent: 4920017 (1990-04-01), Herscovici
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International Search Report (Sep. 04, 1992).
Abstract of Japanese Application No. JP 880134998, filed Jun. 01, 1988.
Haddadi-Asl Vahid
Kazacos Maria Skyllas
Kazacos Michael
Zhong Shihuang
Bell Bruce F.
Unisearch Limited ACN 000 263 025
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