Aluminum anodes and method of manufacture thereof

Abstract

A process of making an aluminum alloy anodic material having improved electrochemical properties for use in an electrochemical cell and battery, the alloy consisting essentially of 95-99.5% w/w Al and 0.5-5.0 cumulative w/w additive metal selected from Group II-Group V metals of the Periodic Table, the process comprising heating 95-99.5% w/w Al and 0.5-5.0 cumulative % w/w additive metal in admixture to a temperature to form a homogeneous matrix of melted alloy; cooling the melted alloy at a liquidus/solidius cooling rate to produce a solid, non-equilibrium alloy of a non-homogenous multiphase matrix comprising discrete, relatively large crystals of pure aluminum and relatively smaller crystals of the additive metal included at the interface with the aluminum crystals; rolling the solid alloy to reduce its thickness to a factor of 0.2 to 0.01 to produce a rolled sheet of the alloy having a microstructure comprising an aluminum matrix having elongate inclusions of the additive metal and small, satellite ovoidal inclusions of the additive metal dispersed in the matrix.

1 . A process of making an aluminum alloy anodic material having improved electrochemical properties for use in an electrochemical cell, said alloy consisting essentially of 95-99.5% w/w Al and 0.5-5.0 cumulative w/w additive metal selected from Group II-Group V metals of the Periodic Table, said process compromising heating 95-99.5% w/w Al and 0.5-5.0 cumulative % w/w additive metal in admixture to a temperature to form a homogeneous matrix of melted alloy; 
 cooling said melted alloy at a liquidus/solidus cooling rate to produce a solid, non-equilibrium alloy of a multiphase matrix comprising discrete, relatively large crystals of pure aluminum and relatively smaller crystals of said additive metal included at the interface with said aluminum crystals;    rolling said solid alloy to reduce its thickness to a factor of 0.2 to 0.01 to produce a rolled sheet of said alloy having a microstructure comprising an aluminum matrix having elongate inclusions of said additive metal and small, satellite ovoidal inclusions of said additive metal dispersed in said matrix.    
     
     
         2 . A process as defined in  claim 1  wherein said cooling rate of said melted alloy is selected from 1° to 10° C. per minute.  
     
     
         3 . A process as defined in  claim 2  wherein said cooling rated is selected from 2-5° C. per minute.  
     
     
         4 . A process as defined in  claim 1  wherein about 80-90% w/w of said additive metal in said rolled alloy is in the form of said elongate inclusions and about 10-20% w/w is in the form of said ovoidal inclusions.  
     
     
         5 . A process as defined in  claim 1  wherein said elongate inclusion has a length selected from 2-30 microns, a width selected from 0.4-3 microns; and said ovoidal inclusion has a diameter selected from 0.1-0.3 microns.  
     
     
         6 . A process as defined in  claim 1  wherein said additive metal is selected from Ga, In, Tl, Cd, Sn, Pb, Mn, Fe, and Mg.  
     
     
         7 . A process as defined in  claim 6  wherein said additive metal is selected from Sn, In, Mn and Fe.  
     
     
         8 . A process as defined in  claim 6  wherein said alloy consists essentially of 99.4% w/w Al and 0.6% w/w In.  
     
     
         9 . A process as defined in  claim 1  wherein said solid alloy is hot rolled to 10-20% of original thickness and subsequently cold rolled to 2-10% of original thickness.  
     
     
         10 . A process as defined in  claim 1  wherein said solid alloy is rolled to a thickness selected from 0.2-1mm.  
     
     
         11 . A process as defined in  claim 1  wherein said aluminum crystals in said pre-rolled solid alloy have an average length selected from up to 5 cm and a width of 0.2-1 mm.  
     
     
         12 . An aluminum alloy having improved electrochemical properties for use as an anode in an electrochemical cell consisting essentially of 95-99.5% w/w aluminum and 0.5-5.0 cumulative % w/w additive metal selected from Group II-Group V metals of the Periodic Table, and having a microstructure comprising an aluminum matrix having elongate inclusions of said additive metal and smaller, satellite ovoidal inclusions of said additive metal dispersed in said matrix.  
     
     
         13 . An alloy as defined in  claim 12  wherein about 80-90% w/w of said additive metal is in the form of said elongate inclusions dispersed in said matrix.  
     
     
         14 . An alloy as defined in  claim 12  wherein said elongate inclusion has a length selected from 2-30 microns and a width selected from 0.4-3 microns; and said ovoidal inclusions has a diameter selected from 0.1-0.3 microns.  
     
     
         15 . An alloy as defined in  claim 12  wherein said additive metal is selected from Ga, In, Tl, Cd, Sn, Pb, Mn, Fe, and Mg.  
     
     
         16 . An alloy as defined in  claim 12  wherein said additive metal is In at a concentration of about 0.5% w/w.  
     
     
         17 . An electrochemical cell comprising an anode, a cathode, and an electrolyte, wherein said anode is formed of an alloy as defined in  claim 12 .  
     
     
         18 . A battery comprising an anode, a gas-diffusion cathode, and an alkali metal electrolyte; wherein said anode is formed of an alloy as defined  claim 12  and is in the form of a tape, foil or sheet having a thickness selected from 0.05 mm-2 cm.