National Power Plc

Ralph Zito

An electrochemical apparatus for energy storage and/or power delivery comprises multi-compartment cells with the +.sup.ve chamber and the -.sup.ve chamber of each cell being separated by at least one buffer chamber through which an idler electrolyte circulates, the electrolyte circulating through the -.sup.ve chamber during power delivery containing sulfide and the apparatus comprising means for restoring the electrolyte balance of the -.sup.ve electrolyte by the oxidation of any S.sup.2- and/or HS.sup.- ions contained in the idler electrolyte to form sulfur, means for the collection of precipitated sulfur and means for the reintroduction of the precipitated sulfur into the -.sup.ve electrolyte.

Process for energy storage and/or power delivery with means for

An electrochemical apparatus for power delivery employs an array of electrochemical cells which comprises an end +.sup.ve electrode and an end -.sup.ve electrode separated by one or more bipolar mid-electrodes each with a +.sup.ve side and a -.sup.ve side, the +.sup.ve side of each bipolar electrode comprising an electrically conductive substrate with a porous conductive surface. A bubbly dispersion of air/oxygen in an electrolyte is contacted with the +.sup.ve sides of the bipolar electrodes. The electrochemical apparatus of the invention may be used with an oxygen-sulfur couple with these reagents being provided for example as sodium salts in aqueous solutions, the overall reaction being:

Electrochemical apparatus for power delivery utilizing an air electrode

An electrochemical apparatus for energy storage and power generation comprises a single cell or an array of unit cells (10), each cell comprising a +.sup.ve electrode (12) and a -.sup.ve electrode (14) with a dual membrane in each cell dividing it into +.sup.ve chambers (22C and 24C) for posilyte and anolyte solutions (22, 24) which are recirculated through separate pumps (26, 28) and storage tanks (32, 34) and back to the chambers. The dual membranes in each cell provide a third chamber (23C) between the +.sup.ve chamber (22C) and the -.sup.ve chamber (24C), through which an idler electrolyte is circulated. During the operation of the cell, any ionic species which cross the cation exchange membranes, which in an ideal system would remain in either the +.sup.ve chamber or the -.sup.ve chamber of the cell, will collect in the buffer chamber or chambers.

Electrochemical apparatus for energy storage and/or power delivery

An electrochemical process for energy storage and/or power generation and apparatus comprises cell array of unit cells (10), each cell comprising a +.sup.ve electrode (12) and a -.sup.ve electrode (14) with a membrane in each cell dividing it into +.sup.ve and -.sup.ve chambers (22C and 24C) for catholyte and anolyte solutions (22, 24) which are recirculated through separate pumps (26, 28) and storage tanks (32, 34) and back to the chambers. Mid electrodes, between adjacent cells in the array, provide both a +.sup.ve side and a -.sup.ve side. A bromine-sulfur couple may be employed. Means are provided to compensate for pH changes and/or changes in hydroxyl ion concentration in the +.sup.ve and/or the -.sup.ve sides of the array of cells. Means are provided to affect some limited occurrence of trans-membrane migration or other losses of bromine, sulfur and/or water and to limit the effects of bromine acidification, while affording high energy storage and high power with stable operation over long periods and to maintain output power and voltage at high levels throughout substantially all the discharge cycle.

Electrochemical energy storage and/or power delivery cell with pH control

An electrochemical process for energy storage and power generation comprises a single cell or an array of unit cells (10), each cell comprising a positive electrode (12) and a negative electrode (14) with a membrane in each cell dividing it into positive and negative chambers (22C and 24C) for posilyte and anolyte solutions (22, 24) which are recirculated through separate pumps (26, 28) and storage tanks (32, 34) and back to the chambers. An iron-sulfur couple is employed, the overall reaction being:

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Chapel Hill, NC, United States of America

Ralph Zito