Electroplating Transitional Metal Oxides

Abstract

The present disclosure generally relates to a method for electroplating (or electrodeposition) a transition metal oxide composition that may be used in gas sensors, biological cell sensors, supercapacitors, catalysts for fuel cells and metal air batteries, nano and optoelectronic devices, filtration devices, structural components, and energy storage devices. The method includes electrodepositing the electrochemically active transition metal oxide composition onto a working electrode in an electrodeposition bath containing a molten salt electrolyte and a transition metal ion source. The electrode structure can be used for various applications such as electrochemical energy storage devices including high power and high-energy primary or secondary batteries.

What is claimed is: 
     
         1 . A method of electrodepositing a transition metal oxide, doped transition metal oxide or sodiated transition metal oxide onto the surface of a working electrode comprising the steps of:
 (a) immersing a working electrode into a molten salt electrolyte comprising a transition metal ion source in the presence of an inert atmosphere,   (b) electrodepositing an electrochemically active transition metal oxide onto a surface of the working electrode from the molten salt electrolyte at a temperature in excess of the melting temperature of the molten salt electrolyte,   (c) removing the working electrode from the bath,   (d) rinsing the electrodeposited transition metal oxide,   (e) followed by heat treatment of the electrodeposited transition metal oxide.   
     
     
         2 . The method of  claim 1  wherein the transition metal oxide is Co 3 O 4 , CoO, MnO 2 , Mn 2 O 3 , Mn 3 O 4  or a mixture of Mn and Co metal oxide Mn x Co y O z  where x, y and z range from 0.1 to 4. 
     
     
         3 . The method of  claim 1  wherein the molten salt electrolyte comprises a hydroxide salt, a halide salt, a nitrate salt, a sulfate salt or a combination thereof. 
     
     
         4 . The method of  claim 3  wherein the molten salt electrolyte comprises a hydroxide salt selected from the group consisting of KOH, NaOH, RbOH, and CsOH, a halide salt selected from the group consisting of KF, KCl, NaCl, NaF, NaBr, KBr, NaI, KI, and AlCl 3 , a nitrate salt selected from the group consisting of NaNO 3 , and KNO 3 , a nitrite salt selected from the group consisting of NaNO 2 , and KNO 2 , a sulfate salt selected from the group consisting of Na 2 SO 4 , and K 2 SO 4 , or a combination thereof. 
     
     
         5 . The method of  claim 4  wherein the molten salt comprises NaOH and Co(OH) 2 , and the electrodeposited transition metal oxide is Na x Co y O 2 , wherein x is between 0.1 to 1 and y is between 1 to 0.1. 
     
     
         6 . The method of  claim 4  wherein the molten salt comprises NaOH and MnCl 2 , and the electrodeposited transition metal oxide is Na x Mn y O 2 , wherein x is between 0.1 to 1 and y is between 1 to 0.1. 
     
     
         7 . The method of  claim 1  wherein the working electrode comprises an electrically conductive material selected from the group consisting of electrically conductive carbon, metal, metal alloys, metallic ceramics, oxides, polymers, and combinations thereof. 
     
     
         8 . The method of  claim 7  wherein the working electrode is an electrically conductive metal selected from the group consisting of aluminum, copper, chromium, cobalt, manganese, nickel, silver, gold, tin, platinum, zinc, tungsten, tantalum, rhodium, molybdenum, titanium, iron, zirconium, vanadium, hafnium, and the alloys thereof. 
     
     
         9 . The method of  claim 1 , wherein the transition metal ion source comprises at least one of cobalt, manganese, nickel, copper, iron, chromium, vanadium, titanium, molybdenum, and tungsten, and combinations thereof. 
     
     
         10 . The method of  claim 9 , wherein the transition metal ion source in the plating bath further comprises at least one of an oxide doping agent selected from the group consisting of A 1   2 O 3 , AlOH 3 , and combinations thereof. 
     
     
         11 . The method  claim 1  wherein the transition metal oxide is confonnally coating onto the working electrode. 
     
     
         12 . The method  claim 11  wherein the working electrode is a porous nanostructured component and wherein the transition metal oxide is conformally coating onto the porous nanostructured component. 
     
     
         13 . The method of  claim 12 , wherein the working electrode used for electrodeposition of the transition metal oxides is porous with 3D interconnected pore structures. 
     
     
         14 . The method of  claim 1 , wherein the electrodeposition temperature is from about 150° to about 600° C. 
     
     
         15 . The method of  claim 14 , wherein the electrodeposition temperature is from about 300° to about 500° C. 
     
     
         16 . The method of  claim 1  wherein the thickness of the electrodeposited transition metal oxide ranges from 10 nm to 100 μm. 
     
     
         17 . The method of  claim 1  wherein the electrodeposited transition metal oxide material is in the form of a powder and wherein the powder can be scraped off. 
     
     
         18 . A method of electrochemical deposition of transition metal oxides, doped transition metal oxides and sodiated transition metal oxide, the method comprising: making a plating bath, comprising NaOH, KOH, or fused melts of an NaOH/KOH eutectic mixture, dissolving a transition metal, providing a conductive substrate, and depositing an electrochemically active transition metal oxide material on the substrate at relatively low temperatures ranging from 150° C. to 600° C. 
     
     
         19 . The method of  claim 18 , wherein the conductive substrate used for electrodeposition comprises at least one of nickel, tungsten, copper, gold, platinum, titanium, and carbon. 
     
     
         20 . The method of  claim 19 , wherein the conductive substrate used for electrodeposition is porous with 3D interconnected pore structures.