Zinc electrode particle form

Abstract

A primary electrochemical cell with an anode comprising zinc alloy particles suspended in a fluid medium is disclosed. The zinc alloy particles include at least about 10 percent, by weight, of fines (particles of −200 mesh size) or dust (particles of −325 mesh size). The zinc particles are preferably alloyed with indium or bismuth and of acicular or flake form. The anode has a low resistivity at low zinc loadings, and the cell demonstrates good mechanical stability and overall performance.

What is claimed is:  
     
         1 . A negative electrode for an electrochemical cell, comprising zinc alloy particles suspended in a fluid medium, at least about 10 percent, by weight, of the zinc alloy particles being of −200 mesh size or smaller.  
     
     
         2 . The negative electrode of  claim 1 , wherein at least about 25 percent, by weight, of the zinc alloy particles are of −200 mesh size or smaller.  
     
     
         3 . The negative electrode of  claim 2 , wherein at least about 50 percent, by weight, of the zinc alloy particles are of −200 mesh size or smaller.  
     
     
         4 . The negative electrode of  claim 3 , wherein at least about 80 percent, by weight, of the zinc alloy particles are of −200 mesh size or smaller.  
     
     
         5 . The negative electrode of  claim 1 , wherein at least about 10 percent, by weight, of the zinc alloy particles are of −325 mesh size or smaller.  
     
     
         6 . The negative electrode of  claim 5 , wherein at least about 45 percent, by weight, of the zinc alloy particles are of −325 mesh size or smaller.  
     
     
         7 . The negative electrode of  claim 6 , wherein at least about 80 percent, by weight, of the zinc alloy particles are of −325 mesh size or smaller.  
     
     
         8 . The negative electrode of  claim 1  further including a surfactant.  
     
     
         9 . The negative electrode of  claim 1  wherein the fluid medium comprises an electrolyte and a thickening agent.  
     
     
         10 . The negative electrode of  claim 9  wherein the zinc alloy particles include a plating material from the group consisting of indium and bismuth.  
     
     
         11 . The negative electrode of  claim 1  wherein at least about 25 percent, by weight, of the zinc alloy particles are between about 20 and 200 mesh size.  
     
     
         12 . The negative electrode of  claim 11  wherein at least about 50 percent, by weight, of the zinc alloy particles are between about 20 and 200 mesh size.  
     
     
         13 . The negative electrode of  claim 1  wherein the zinc alloy particles are generally acicular, having a length along a major axis at least two times a length along a minor axis.  
     
     
         14 . The negative electrode of  claim 1  wherein the zinc alloy particles are generally flakes, each flake generally having a thickness of no more than about 20 percent of the maximum linear dimension of the particle.  
     
     
         15 . A negative electrode mixture for an electrochemical cell, comprising zinc alloy particles suspended in a fluid medium with the zinc alloy particles comprising less than about 55 percent of the electrode mixture, by weight; the zinc alloy particles including a sufficient proportion of particles of about −200 mesh size or smaller to provide an electrode resistivity of less than about 0.2 ohm-centimeters.  
     
     
         16 . The negative electrode mixture of  claim 15  wherein the zinc alloy particles comprise less than about 45 percent, by weight, of the electrode mixture.  
     
     
         17 . The negative electrode mixture of  claim 15 , wherein at least about 10 percent, by weight, of the zinc alloy particles are of −200 mesh size or smaller.  
     
     
         18 . The negative electrode mixture of  claim 17 , wherein at least about 10 percent, by weight, of the zinc alloy particles are of −325 mesh size or smaller.  
     
     
         19 . The negative electrode mixture of  claim 15  wherein at least about 25 percent, by weight, of the zinc alloy particles are between about 20 and 200 mesh size.  
     
     
         20 . A primary electrochemical cell having 
 a cathode,    an anode comprising zinc alloy particles suspended in a fluid medium, at least 10 percent, by weight, of the zinc alloy particles being of −200 mesh size or smaller, and    a separator between the cathode and the anode.    
     
     
         21 . The primary electrochemical cell of  claim 20 , wherein at least about 25 percent, by weight, of the zinc alloy particles are of −200 mesh size or smaller.  
     
     
         22 . The primary electrochemical cell of  claim 21 , wherein at least about 50 percent, by weight, of the zinc alloy particles are of −200 mesh size or smaller.  
     
     
         23 . The primary electrochemical cell of  claim 22 , wherein at least about 80 percent, by weight, of the zinc alloy particles are of −200 mesh size or smaller.  
     
     
         24 . The primary electrochemical cell of  claim 20 , wherein at least about 10 percent, by weight, of the zinc alloy particles are of −325 mesh size or smaller.  
     
     
         25 . The primary electrochemical cell of  claim 24 , wherein at least about 45 percent, by weight, of the zinc alloy particles are of −325 mesh size or smaller.  
     
     
         26 . The primary electrochemical cell of  claim 25 , wherein at least about 80 percent, by weight, of the zinc alloy particles are of −325 mesh size or smaller.  
     
     
         27 . A negative electrode slurry for an electrochemical cell, comprising zinc alloy particles suspended in a fluid medium including an electrolyte, the slurry having a resistivity of less than about 0.2 ohm-centimeters and the zinc alloy particles comprising less than about 55 percent, by weight, of the slurry.  
     
     
         28 . A method of generating an electric current, comprising accumulating ions on the surface of zinc alloy particles suspended in a fluid medium containing an electolyte, at least about 10 percent, by weight, of the zinc alloy particles being of −200 mesh size or smaller.