Rechargeable Cells with Modified MnO2 Cathodes

Abstract

The recent invention of rechargeable "modified" manganese oxide materials paves the way to the development of secondary batteries suitable for numerous applications. This includes alternatives to primary dry cells, and secondary lead/ acid and nickel-cadmium batteries. Present results describe the performance of cells in which the modified materials are coupled with zinc and iron. As opposed to iron which does not affect the longevity and capacity retention of the modified electrodes, zinc has a pejorative effect on modified MnO2 materials, owing to the formation of hetaerolite at the positive electrode. Methods to alleviate this effect and produce viable modified MnO2/Zn systems are described. At present, these systems retain about 50% of their theoretical one-electron capacity even after two hundred fast charge-discharge cycles.

Examining manganese dioxide electrode in KOH electrolyte using TEM technique

“…As the active material loading decreases, the internal resistance decreases and the capacity utilization and working voltage increase. Wroblowa et al [8,26] who reported a cycling of 1.9 electrons at 10% active material loading. Hence this could be accounted for the observed higher discharge capacity.…”

Thermal stabilization of tin- and cobalt-doped manganese dioxide

“…The mentioned processes in alkaline cells are based on several electrochemical reactions of Mn oxides, particularly on electrochemical redox cycling of Mn IV /Mn III /Mn II , and possibly on chemical reactions of the reduced Mn species with oxygen [27][28][29][30][31][32]. Figure 10 depicts the typical cyclic voltammograms of MnO 2 //C alkaline cells using undoped-and doped-MnO 2 cathode materials.…”

Power generation/energy storage by a fuel cell/battery system: Regeneration of the MnO2 positive electrode with gaseous oxygen

“…The electrochemical discharge of electrodeposited manganese dioxide (EMD) can be represented as follows [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]:…”

“…We thus expect that MnO 2 would satisfy the requirements for the positive electrode of the FCB system as it can be charged by oxygen gas and by the supply of electric power. Many papers have reported rechargeable manganese dioxide electrodes in aqueous solutions by restricting the depth of discharge [25,26,42], by adding metals [26][27][28][29][30][31][32][33][34][35]42] and by oxygenregeneration of the discharged manganese dioxide electrodes (MnOOH) [40][41][42][43]. However, few studies exist describing the gaseous charging of discharged manganese dioxide (MnOOH) by oxygen.…”