Electrochemical cells including secondary batteries and fuel cells are provided employing polyanilines having improved reversibility, stability and electrochemical properties. In accordance with a preferred embodiment polyaniline is employed as a cathode active polymer in a secondary battery at a pH between about 1 and 11. In accordance with other embodiment, fuel cells employing polyaniline are provided as are batteries wherein polyanilines are used as anodes.
A battery electrode is obtained by coating an electrically conductive film serving as a collector with an aqueous solution of formic acid containing polypyridine, which is an active material, in dissolved form as well as carbon powder serving as a conduction aid, and drying the solution on the film. A secondary battery is manufactured using such electrodes.
Carbon steel substrates are protected from corrosive environments by a coating of nonconductive poly(aniline) which has been chemically prepared and cast onto the substrate from solution. The coating can also include other polymers which are miscible with the poly(aniline) but do not protonate it so as to make it conductive. Such polymers can include polyimides, epoxies, and urethane linked diisocyanates, among others. In these blends, a weight composition of at least 5% poly(aniline) to the other polymer is preferred. Overall, the nonconductive form of polyaniline has been found to be more effective in this service than the conductive form. Air oxidation of the poly(aniline) coating before exposure to a corrosive environment enhances the benefits.
The invention provides a fuel cell which comprises a solid polymer electrolyte sandwiched between a cathode to which an oxidizing agent gas is supplied and an anode to which a reducing agent gas is supplied, wherein at least one of the electrodes has an electroconductive organic polymer which has an oxidation-reduction function as an electrode catalyst. The invention further provides a fuel cell in which the electrode catalyst comprises a mixture of an electroconductive organic polymer and an inorganic oxidation-reduction catalyst, and has a higher output power.
An electrode comprises a porous carbon sheet comprising (a) carbon fibers and (b) a carbon matrix which comprises carbon particles and is integrally combined with the carbon fibers, having continuous through-holes. This electrode can be used as a cathode or anode for a battery. This type of electrode is prepared by depositing a phenolic resin on a phenolic resin sheet comprising phenolic resin fibers, and carbonizing the phenolic resin and the phenolic resin sheet in an oxygen-free atmosphere at temperatures in the range of 500.degree. C. to 3000.degree. C.
