US 4,485,154 AGranted

Electrically rechargeable anionically active reduction-oxidation electrical storage-supply system

AssigneeInstitute of Gas Technology

InventorsRobert J. Remick, Peter G. P. Ang

Life of this patent

Estimating the term…

Loading patent…

Abstract

An electrically rechargeable anionically active reduction-oxidation electric storage-supply system and process is disclosed using a sodium or potassium sulfide-polysulfide anolyte reaction and an iodide-polyiodide, chloride-chlorine or bromide-bromine species catholyte reaction. The catholyte and anolyte are separated by an ion selective membrane permeable to positive sodium and potassium ions and substantially impermeable to negative bromide, chloride, iodide, sulfide and polysulfide ions. A flowing electrolyte system is disclosed with external electrolyte storage vessels. The apparatus and process provide an electrically rechargeable anionically active reduction-oxidation system in which the electrolytes may be maintained at near neutral or slightly basic pH, with virtually no parasitic side reactions upon charging, such as hydrogen or oxygen evolution, and the disclosed storage and supply system provides higher energy densities than referenced prior art systems.

Claims47

Dependent claims

An electrically rechargeble anionically active reduction-oxidation electrical energy storage and supply system comprising:

an electrochemical cell comprising an anolyte compartment and a catholyte compartment separated by an ion selective membrane permeable to positive sodium and potassium ions and substantially impermeable to negative bromide, chloride, iodide, sulfide and polysulfide ions and a first and a second electrode disposed in said anolyte and catholyte compartments, respectively;
anolyte supply means providing anionically active ions in an aqueous solution electrochemically reactable anolyte in contact with said first electrode, said first electrode being substantially chemically non-reactive with said anolyte;
catholyte supply means providing anionically active ions in an aqueous solution electrochemically reactable catholyte in contact with said second electrode, said second electrode being substantially chemically non-reactive with said catholyte;
said anolyte and said catholyte having all active reduction-oxidation couples as anions;
and
an external electrical circuit in electrical communication with said first and second electrodes, said electrical circuit comprising an electrical load means and a direct current supply means for applying charging voltage to said electrodes electrically connected in parallel in said circuit between said electrodes, and switching means for electrical circuit selection between said load means, said supply means, and an open circuit.

3 more elements

A process for electrical energy storage and supply by an electrically rechargeable anionically active reduction-oxidation system having all active reduction-oxidation couples as anions comprising:

A. storing electrical energy in said system by the steps comprising:
passing direct current charging voltage across a first and second electrode providing electrons to said first electrode;
reducing polysulfide compounds selected from the group consisting of sodium and potassium and mixtures thereof to corresponding lower polysulfide and sulfide compounds in an anolyte in contact with said first electrode;
oxidizing halide ions selected from the group consisting of iodide, chloride, bromide and mixtures thereof to corresponding polyiodide, chlorine and bromine species in a catholyte in contact with said second electrode;
and
positive ions selected from the group consisting of sodium, potassium and mixtures thereof passing through an ion selective membrane, substantially impermeable to negative bromide, chloride, iodide, sulfide and polysulfide ions, from said catholyte to said anolyte to complete the electrical circuit;
and
B. supplying electrical energy from said system by the steps comprising:
passing current from said first and second electrode to an electrical load providing electrons to said second electrode;
oxidizing said sulfide and lower polysulfide compounds to corresponding higher polysulfide compounds in an anolyte in contact with said first electrode;
reducing said polyiodide, chlorine or bromine species to said halide ions in a catholyte in contact with said second electrode;
and
said positive ions passing through said ion selective membrane from said anolyte to said catholyte to complete the electrical circuit.

10 more elements

Dependencies are inferred from the claim text.