US4758473A — Stable carbon-plastic electrodes and method of pr…

Claim 1

Independent Claim 138 words

A bipolar electrode element for electrochemical cells comprising: a pressure-molded composite of heat-treated electrically conductive graphite particles having a particle size distribution before molding of 0 to 45 μm, said graphite being heat-treated at a temperature of at least 800° C. in air for 2 hours prior to forming said composite; and thermoplastic fluoropolymer resin particles having a particle size distribution before molding of 0 to 45 μm, said graphite and said resin in said composite being in a weight ratio of from 1:5 to 1:1; said composite characterized by less than 4.0% weight loss and less than 0.1% dimensional increase in length upon immersion at 60° C. into polybromide oil for 1600 hours; and said composite being formed by pressure-molding a mixture comprising said graphite and said resin at 400 kg/cm 2 or above at 190° C.

Claim 2

Dependent Claim 138 words

A bipolar electrode element for electrochemical cells comprising: a pressure-molded composite of heat-treated electrically conductive graphite particles having a particle size distribution before molding of 0 to 45 μm, said graphite being heat-treated at a temperature of at least 800° C. in air for 2 hours prior to forming said composite; and thermoplastic fluoropolymer resin particles having a particle size distribution before molding of 0 to 45 μm, said graphite and said resin in said composite being in a weight ratio of from 1:5 to 1:1; said composite characterized by less than 4.0% weight loss and less than 0.1% dimensional increase in length upon immersion at 60° C. into polybromide oil for 1600 hours; and said composite being formed by pressure-molding a mixture comprising said graphite and said resin at 400 kg/cm 2 or above at 190° C.

Claim 3

Dependent Claim 38 words

A bipolar element according to claim 1 characterized by a resistivity of less than 0.8 ohm-cm and a flexural strength of at least 2400 psi upon immersion at 60° C. into polybromide oil for at least 2300 hours.

Claim 4

Dependent Claim 42 words

A bipolar element according to claim 1 further comprising up to 2% by weight of a perfluorohydrocarbon wherein said graphite, said resin and said perfluorohydrocarbon are calendered with a hydrocarbon carrier into preformed shapes prior to being subjected to said pressure molding.

Claim 5

Dependent Claim 12 words

A bipolar element according to claim 3 wherein said perfluorohydrocarbon comprises polytetrafluoroethylene.

Claim 6

Dependent Claim 14 words

A bipolar element according to claim 1 wherein said thermoplastic resin comprises polyvinylidene difluoride.

Claim 7

Dependent Claim 23 words

A bipolar element according to claim 5 wherein said graphite and said resin in said composite are in a weight ratio of 1:1.

Claim 8

Dependent Claim 29 words

A bipolar assembly comprising a bipolar element according to claim 1 and a composite carbon felt, said felt and said element being held in interfacial contact with an adhesive.

Claim 9

Dependent Claim 19 words

A bipolar assembly according to claim 7 wherein said adhesive is formed from carbon, polyvinylidene difluoride resin and dimethylformmide.

Claim 10

Independent Claim 157 words

A method of making a bipolar element for electrochemical cells comprising the steps of: (a) dry mixing electrically conductive graphite particles with thermoplastic resin particles, said graphite particles having a particle size distribution of 0 to 45 μm, said graphite further being heat-treated at a temperature of at least 800° in air for 2 hours; said graphite and said resin being in a weight ratio of from 1:5 to 1:1, with up to 2% by weight of a perfluorohydrocarbon binder; (b) screening the mixture from step (a) to form a particulate mixture of average particle size of 0 to 45 μm; (c) forming a wet mixture of the particulate mixture from step (b) with a liquid hydrocarbon carrier and calendering said wet mixture into sheets; (d) drying said sheets from step (c); (e) compression molding said sheets from step (d) under a pressure of at least 400 kg/cm 2 at 190° C. to form said bipolar elements.

Claim 11

Independent Claim 157 words

A method of making a bipolar element for electrochemical cells comprising the steps of: (a) dry mixing electrically conductive graphite particles with thermoplastic resin particles, said graphite particles having a particle size distribution of 0 to 45 μm, said graphite further being heat-treated at a temperature of at least 800° in air for 2 hours; said graphite and said resin being in a weight ratio of from 1:5 to 1:1, with up to 2% by weight of a perfluorohydrocarbon binder; (b) screening the mixture from step (a) to form a particulate mixture of average particle size of 0 to 45 μm; (c) forming a wet mixture of the particulate mixture from step (b) with a liquid hydrocarbon carrier and calendering said wet mixture into sheets; (d) drying said sheets from step (c); (e) compression molding said sheets from step (d) under a pressure of at least 400 kg/cm 2 at 190° C. to form said bipolar elements.

Claim 12

Dependent Claim 14 words

A method according to claim 9 wherein said perfluorohydrocarbon in step (a) comprises polytetrafluoroethylene.

Claim 13

Dependent Claim 13 words

A method according to claim 9 wherein said thermoplastic resin comprises polyvinylidene difluoride.

Claim 14

Independent Claim 114 words

A method of making a bipolar element for electrochemical cells comprising the steps of: (a) dry mixing electrically conductive graphite particles and thermoplastic resin particles, said graphite having a particle size distribution of 0 to 45 μm, said graphite further being heat-treated at a temperature of at least 800° C. for 2 hours; said graphite and said resin being in a weight ratio of from 1:5 to 1:1; (b) screening the mixture from step (a) to form a particle mixture of average particle size of 0 to 45 μm; (c) compression molding said mixture from step (b) under a pressure of at least 400 kg/cm 2 at 190° C. to form said bipolar element.

Claim 15

Independent Claim 114 words

A method of making a bipolar element for electrochemical cells comprising the steps of: (a) dry mixing electrically conductive graphite particles and thermoplastic resin particles, said graphite having a particle size distribution of 0 to 45 μm, said graphite further being heat-treated at a temperature of at least 800° C. for 2 hours; said graphite and said resin being in a weight ratio of from 1:5 to 1:1; (b) screening the mixture from step (a) to form a particle mixture of average particle size of 0 to 45 μm; (c) compression molding said mixture from step (b) under a pressure of at least 400 kg/cm 2 at 190° C. to form said bipolar element.

Claim 16

Dependent Claim 14 words

A method according to claim 12 wherein said thermoplastic resin particles comprise polyvinylidene difluoride.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-07-19	1992-01-18	1992-07-19	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-07-19	1996-01-18	1996-07-19	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-07-19	2000-01-18	2000-07-19	$7700.00	Window Closed / Lapsed

Stable carbon-plastic electrodes and method of preparation thereof

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag