Hydrogen-absorbing alloy electrode for use in an alkaline storage cell and its manufacturing method

Abstract

A hydrogen-absorbing alloy electrode for use in an alkaline storage cell, comprising a hydrogen-absorbing alloy for reversibly absorbing and desorbing hydrogen; and a metal oxide or metal hydroxide existing in the state of a metal in a range of electric potential where said hydrogen-absorbing alloy electrochemically absorbs and desorbs hydrogen in an alkaline electrolyte.

What is claimed is: 
     
       1. A hydrogen-absorbing alloy electrode for use in an alkaline storage cell, the electrode comprising: a hydrogen-absorbing alloy for reversibly absorbing and desorbing hydrogen; and   a metal oxide existing in the state of a metal in a range of electric potential where said hydrogen-absorbing alloy electrochemically absorbs and desorbs hydrogen in an alkaline electrolyte;   wherein said metal oxide is at least one selected from the group consisting of CuO, Cu 2  O, Ag 2  O, Ag 2  O 2 , PbO, .[.Ti 2  O 3 ,.]. AuO 2  and Au 2  O 3 .   
     
     
       2. A hydrogen-absorbing alloy electrode of claim 1, wherein said metal oxide has an average grain size of 50 μm at the maximum. 
     
     
       3. A hydrogen-absorbing alloy electrode of claim 1, wherein an amount of said metal oxide is set so that an amount of electricity required to reduce said metal oxide into a metal is 15% at the maximum of a capacity of the hydrogen-absorbing alloy electrode. 
     
     
       4. A hydrogen-absorbing alloy electrode for use in an alkaline storage cell, the electrode comprising: a hydrogen-absorbing alloy for reversibly absorbing and desorbing hydrogen; and   a metal hydroxide existing in the state of a metal in a range of electric potential where said hydrogen-absorbing alloy electrochemically absorbs and desorbs hydrogen in an alkaline electrolyte;   wherein said metal hydroxide is at least one selected from the group consisting of Cu(OH) 2  .[., Ti(OH) 3  .]. and Au(OH) 3 .   
     
     
       5. A hydrogen-absorbing alloy electrode of claim 4, wherein said metal hydroxide has an average grain size of 50 μm at the maximum. 
     
     
       6. A hydrogen-absorbing alloy electrode of claim 4, wherein an amount of said metal hydroxide is set so that an amount of electricity required to reduce said metal hydroxide into a metal is 15% at the maximum of a capacity of the hydrogen-absorbing alloy electrode. 
     
     
       7. A manufacturing method of a hydrogen-absorbing alloy electrode for use in an alkaline storage cell, comprising the steps of: producing hydrogen-absorbing alloy powders;   kneading the above powders, a metal oxide existing in the state of a metal in a range of electric potential where the hydrogen-absorbing alloy electrochemically absorbs and desorbs hydrogen in an alkaline electrolyte, and a binder into a paste, wherein the metal oxide is at least one selected from the group consisting of CuO, Cu 2  O, Ag 2  O, Ag 2  O 2 , PbO, .[.Ti 2  O 3 ,.]. AuO 2  and Au 2  O 3  ;   coating the paste on a conductive substrate.   
     
     
       8. A manufacturing method of claim 7, wherein the metal oxide has an average grain size of 50 μm at the maximum. 
     
     
       9. A manufacturing method of claim 7, wherein an amount of the metal oxide is set so that an amount of electricity required to reduce the metal oxide into a metal is 15% at the maximum of a capacity of the hydrogen-absorbing alloy electrode. 
     
     
       10. A manufacturing method of a hydrogen-absorbing alloy electrode for use in an alkaline storage cell, comprising the steps of: producing hydrogen-absorbing alloy powders;   kneading the above powders, a metal hydroxide existing in the state of a metal in a range of electric potential where the hydrogen-absorbing alloy electrochemically absorbs and desorbs hydrogen in an alkaline electrolyte, and a binder into a paste, wherein the metal hydroxide is at least one selected from the group consisting of Cu(OH) 2  .[., Ti(OH) 3  .]. and Au(OH) 3  ; and   coating the paste on a conductive substrate.   
     
     
       11. The method of claim 10, wherein the metal hydroxide has an average grain size of 50 μm at the maximum. 
     
     
       12. The method of claim 10, wherein an amount of the metal hydroxide is set so that an amount of electricity required to reduce said metal hydroxide into a metal is 15% at the maximum of a capacity of the hydrogen-absorbing alloy electrode.