초록 ▼

The present disclosure is directed to an electrode active layer or sheet containing from about 60 to about 85 wt. % active carbon in intimate admixture with 15 to 40 wt. % fibrillated PTFE. This electrode has improved strength and is capable of operation at high current density with resistance to me

The present disclosure is directed to an electrode active layer or sheet containing from about 60 to about 85 wt. % active carbon in intimate admixture with 15 to 40 wt. % fibrillated PTFE. This electrode has improved strength and is capable of operation at high current density with resistance to mechanical failure due to blistering of the electrode, and to a process for producing same. The process is characterized by combining a dilute dispersion of smaller polytetrafluoroethylene particles with a suspension of catalyzed or uncatalyzed larger active carbon particles to discontinuously coat active carbon with PTFE; fibrillating same; comminuting said fibrillated PTFE/active carbon mix; and then rolling same into a self-sustaining, coherent sheet form. Alternatively, the sheet form can be provided by deposition of the heat treated polytetrafluoroethylenated active carbon on a filter paper or like medium.

대표청구항 ▼

1. A process for forming active layer or sheet comprising adding a dilute aqueous dispersion of polytetrafluoroethylene particles to an aqueous suspension of larger active carbon particles to discontinuously coat said active carbon particles with smaller polytetrafluoroethylene particles; fibrillati

1. A process for forming active layer or sheet comprising adding a dilute aqueous dispersion of polytetrafluoroethylene particles to an aqueous suspension of larger active carbon particles to discontinuously coat said active carbon particles with smaller polytetrafluoroethylene particles; fibrillating said discontinuously coated particles by shear blending at between about 15° C. and 75° C. to form an intimate mix of carbon particles having attenuated adherent polytetrafluoroethylene particles; chopping said intimate mix to yield a granular mix to reduce any compression of the intimate mix during shear blending and nonsinteringly forming said granular mix into a sheet. 2. A process as in claim 1 wherein said granular mix is formed by rolling at temperatures of from about 60° to 90° C. 3. A process as in claim 1 wherein said active carbon particles have a particle size ranging from about 1 to 30 microns. 4. A process as in claim 1 wherein a soluble or volatile particulate pore-forming agent is added to said suspension and blended therewith prior to fibrillating and the pore-forming agent is subsequently removes from the sheet. 5. A process as in claim 1 wherein said granular mix is formed by filtration upon a salt bed filter medium. 6. A process as in claim 1 wherein said granular mix contains from about 60 to 85 wt.% active carbon the remainder being polytetrafluoroethylene. 7. A process as in claim 1 wherein said active carbon particles have an ash content of less than about 4 wt.% and a B.E.T. surface area of about 1000 m 2 /g and higher. 8. A process as in claim 1 which includes depositing a precious metal catalyst on said active carbon particles before adding said dilute polytetrafluoroethylene dispersion thereto. 9. A process as in claim 8 wherein said precious metal is platinum. 10. A process as in claim 8 wherein said precious metal is silver.