Wick-and-pool electrodes for electrochemical cell

Abstract

An electrode system includes a reservoir of liquid-metal reactant, and a wick extending from a submersed location within the reservoir into the molten electrolyte of an electrochemical cell structure. The wick is flooded with the liquid metal and thereby serves as one electrode within the cell. This electrode system has application in high-temperature batteries employing molten alkali metals or their alloys as active material within an electrode submersed within a molten salt electrolyte. It also can be used in electrochemical cells where the purification, separation or electrowinning of liquid metals is accomplished.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: .[.1. A liquid-metal electrode system for providing electrode reactant into an electrode within an electrochemical cell also including a second electrode of opposite polarity, said system comprising a cell structure containing a volume of liquid electrolyte, a reservoir containing said liquid metal outside said volume of liquid electrolyte, a wick having a first portion of its length in contact with said liquid metal within said reservoir, and having a second portion of its length opposite to said first portion submerged within said volume of electrolyte, said wick having sufficiently more attraction for said liquid metal than for said electrolyte to draw said liquid metal into said second portion submerged within said electrolyte..]. .[.2. The electrode system of claim 1 wherein said liquid 
     
        metal comprises liquid lithium or a molten lithium alloy..]. 3. The electrode system of claim .[.1.]. .Iadd.10 .Iaddend.wherein said electrolyte includes .[.an alkali metal or alkaline earth metal 
     
     
        fluoride.]. .Iadd.at least 2 weight percent LiF.Iaddend.. 4. The electrode system of claim .[.1.]. .Iadd.10 .Iaddend.wherein a plurality of wicks are submerged within a single reservoir of liquid metal at their first portions and each of said wicks extending to one of a number of cell structures within which their second portions are submerged in molten electrolyte to serve as electrodes. .[.5. The electrode system of claim 1 wherein said wick comprises a pleated metal structure having a portion submerged within said liquid electrolyte for use as an electrode within said electrochemical cell, said pleated structure includes a V-shaped channel containing liquid metal for use as an electrode reactant..]. .[.6. The electrode system of claim 5 wherein said V-shaped channel has greater 
     
     
        depth than width..]. 7. The electrode system of claim .[.6.]. .Iadd.10 .Iaddend.wherein said V-shaped channels have a depth to width ratio of about 4. .[.8. The electrode system of claim 5 wherein said pleated metal structure comprises a plurality of screen layers of chromium alloy 
     
     
        steel..]. 9. The electrode system of claim .[.1.]. .Iadd.10 .Iaddend.wherein said wick is formed into an inverted U-shape having two side portions, the first of said side portions being submersed in said 
     
     
        liquid metal and the second in said liquid electrolyte. .Iadd.10.  In a liquid-metal electrode system for providing electrode reactant consisting of liquid lithium alloy with about 10 weight percent copper into a negative electrode within a secondary electrochemical cell also including a positive electrode containing FeS as a reactant, said system comprising a cell structure containing a volume of liquid alkali-metal halide electrolyte, a reservoir containing said lithium-copper alloy, an austenitic stainless steel wick having a first portion of its length in contact with said liquid lithium-copper alloy within said reservoir and having a second portion of its length opposite to said first portion, submerged within said volume of electrolyte to serve as said negative electrode, said wick having sufficiently more attraction for said liquid lithium-copper alloy than for said electrolyte to draw said liquid lithium-copper alloy into said second portion submerged within said electrolyte, the improvement wherein said austenitic stainless steel wick throughout its first and second portions consists of a plurality of screen layers pleated so as to have a plurality of longitudinal V-shaped channels alternating with longitudinal V-shaped ridges across the width of the screen layers, said channels having greater depth than width to effectively retain lithium-copper alloy within said first portion as a reservoir and within said second portion as the negative electrode, said first portion of said wick extending above the upper surface and outside the volume of said first electrolyte..Iaddend.