Lithium Metal Electrodes and Methods of Manufacturing

Abstract

A lithium metal electrode is manufactured according to a process that bonds a layer of lithium metal to a conductive substrate on one side and to an ion selective membrane on another side. The lithium metal electrode may be integrated into lithium metal batteries. The inventive lithium metal electrode may be manufactured by a process involving electrolysis of lithium ions from an aqueous lithium salt solution through an ion selective membrane, carried out under a blanketing atmosphere having no more than 10 ppm of non-metallic elements, the electrolysis being performed at a constant current between about 10 mA/cm2 and about 50 mA/cm2, and wherein the constant current is applied for a time between about 1 minute and about 60 minutes.

What is claimed is: 
     
         1 . A method of manufacturing a lithium metal electrode, the method comprising the steps of:
 (1) providing a gas-impermeable container, the container enclosing:
 a blanketing atmosphere, the blanketing atmosphere having no more than 10 ppm of lithium reactive components on a molar basis;
 an electrolytic cell, the electrolytic cell being blanketed completely by the blanketing atmosphere, and including: 
 a first chamber containing a positive electrode, water, and a lithium salt dissolved in the water, thereby forming an aqueous lithium salt solution in contact with the positive electrode; 
 a second chamber containing a conductive substrate configured as a negative electrode, the conductive substrate being immovable within the second chamber, a lithium ion-selective membrane separating the first chamber from the second chamber, the electrolytic cell being configured to allow passage of lithium ions through the lithium ion selective membrane between the first and the second chambers, and to preclude the passage of the water between the first and the second chambers; 
 
   (2) applying a variable voltage in order to maintain a constant current across the negative electrode and the positive electrode, thereby causing lithium ions to cross from the first chamber to the second chamber, through the lithium ion selective membrane, and electroplate a layer of lithium onto the conductive substrate, thereby bonding an inner face of the layer of lithium to the conductive substrate and an outer face of the layer of lithium to the ion selective membrane, thereby forming the lithium metal electrode.   
     
     
         2 . The method of manufacturing a lithium metal electrode according to  claim 1 ,
 wherein prior to step (2), disposing a non-aqueous electrolyte in a space that separates the conductive substrate and the lithium ion-selective membrane, the non-aqueous electrolyte physically contacting both the conductive substrate and the lithium ion selective membrane, and   wherein as lithium ions cross from the first chamber to the second chamber, through the lithium ion selective membrane the lithium ions traverse the non-aqueous electrolyte, and electroplate the layer of lithium onto the conductive substrate, so that as the layer of lithium is formed, the layer of lithium displaces non-aqueous electrolyte from the space between the conductive substrate and the lithium ion-selective membrane thereby bonding an inner face of the first layer of lithium to the conductive substrate and the outer face of the first layer of lithium to the ion selective membrane, thereby forming the lithium metal electrode.   
     
     
         3 . The method of manufacturing a lithium metal electrode according to  claim 1 ,
 wherein prior to step (2) the lithium ion-selective membrane covers the conductive substrate, providing a solid state electrolyte that forms a barrier separating the aqueous lithium salt solution and the conductive substrate, and   wherein as lithium ions cross from the first chamber to the second chamber, through the lithium ion selective membrane, and electroplate the layer of lithium onto the conductive substrate, the inner face of the layer of lithium thereupon bonds to the conductive substrate, and the outer face bonds to the lithium ion selective membrane, thereby forming the lithium metal electrode.   
     
     
         4 . The method of manufacturing a lithium metal electrode according to  claim 1 , wherein the constant current is between about 10 mA/cm 2  and about 50 mA/cm 2 , and wherein the constant current is applied for a time between about 1 minute and about 60 minutes. 
     
     
         5 . The method of manufacturing a lithium metal electrode according to any of  claim 1 , wherein the constant current is between about 25 mA/cm 2  and about 50 mA/cm 2 , and wherein the constant current is applied for a time between about 1 minute and about 60 minutes 
     
     
         6 . A lithium metal electrode, manufactured according to the method of  claim 1 . 
     
     
         7 . The lithium metal electrode according to  claim 6 , wherein the electrode has a specific capacity of greater than about 3800 mAh per gram of lithium metal. 
     
     
         8 . The lithium metal electrode according to  claim 6  wherein the layer of lithium metal has a density of between about 0.45 g/cm 3  and about 0.543 g/cm 3 . 
     
     
         9 . The lithium metal electrode according to  claim 6 , wherein the conductive substrate is selected from the group consisting of copper, aluminum, graphite coated copper, and nickel. 
     
     
         10 . The lithium metal electrode according to  claim 6 , the layer of lithium metal having a thickness between about 1 micron and about 50 microns. 
     
     
         11 . The lithium metal electrode according to  claim 6 , the layer of lithium metal having a thickness between about 1 micron and about 10 microns. 
     
     
         12 . A lithium metal battery comprising the lithium metal electrode according to  claim 6 . 
     
     
         13 . The lithium metal battery of  claim 12 , the lithium ion-selective membrane being configured as a solid state electrolyte. 
     
     
         14 . The method of manufacturing a lithium metal electrode according to  claim 1 , wherein the aqueous lithium salt solution comprises a lithium salt selected from the group consisting of Li 2 SO 4 , Li 2 CO 3 , and combinations thereof. 
     
     
         15 . The method of manufacturing a lithium metal electrode according to  claim 14 , wherein the aqueous lithium salt solution comprises Li 2 SO 4 . 
     
     
         16 . The lithium metal electrode according to any of  claim 6 , wherein the lithium ion selective membrane comprises a polymeric matrix and a plurality of ion-conducting particles disposed within the polymeric matrix. 
     
     
         17 . The method of manufacturing a lithium metal electrode according to  claim 1 , wherein the blanketing atmosphere comprises argon with a purity of greater than 99.999 mole percent. 
     
     
         18 . The lithium metal electrode according to  claim 6 , wherein the layer of lithium metal has a purity of no more than 5 ppm of non-metallic elements by mass. 
     
     
         19 . A lithium metal electrode, comprising:
 a conductive substrate;   a lithium ion-selective membrane;   a layer of lithium metal having an inner face and an outer face, the inner face bonded to the conductive substrate, and the outer face bonded to the lithium ion-selective membrane.   
     
     
         20 . The lithium metal electrode according to  claim 19 , wherein the electrode has a specific capacity of greater than about 3800 mAh per gram of lithium metal. 
     
     
         21 . The lithium metal electrode according to  claim 19 , wherein the layer of lithium metal has a density of between about 0.45 g/cm 3  and about 0.543 g/cm 3 . 
     
     
         22 . The lithium metal electrode according to  claim 19 , wherein the conductive substrate is selected from the group consisting of copper, aluminum, graphite coated copper, and nickel. 
     
     
         23 . The lithium metal electrode according to  claim 19 , the layer of lithium metal having a thickness between about 1 micron and about 50 microns. 
     
     
         24 . The lithium metal electrode according to  claim 19 , the layer of lithium metal having a thickness between about 1 micron and about 10 microns. 
     
     
         25 . A lithium metal battery comprising the lithium metal electrode according to  claim 19 . 
     
     
         26 . The lithium metal battery of  claim 25 , the lithium ion-selective membrane being configured as a solid state electrolyte.