350041 The Effect of Varying the Ionic Conductivity, Discharge Rate, Electrode Composition and Thickness on Alkaline MnO2 Cathode

Monday, November 4, 2013
Grand Ballroom B (Hilton)
Rodolfo Ramirez, Chemical Engineering Department, The City College of New York, White Plains, NY, Nilesh Ingale, Chemical Engineering Department, The City College of New York and Sanjoy Banerjee, CUNY Energy Institute, New York, NY; Chemical Engineering Department, City College of New York

Zinc-manganese dioxide (Zn-MnO2) batteries have a long shelf life, have a high energy density and are inexpensive compared to other rechargeable batteries. Yet a rechargeable Zn-MnO2 battery does not exist which is able to recharge more than five hundred times because MnO2 is not rechargeable after its first electron reaction. This research was focused on understanding the discharge behavior of MnO2 electrode in a Zn-MnO2 battery under various conditions. Hence, the effect of ionic conductivity, discharge rates, electrode composition, MnO2 material supplier and electrode thickness on the accessible discharge capacity is studied and analyzed. The MnO2 electrode was discharged to its 1-electron reaction (i.e. 100% depth of discharge, DOD). A galvanostatic technique is used to discharge the MnO2 electrodes in classical three electrode half-cell experiments. In these experiments, the ionic conductivity, controlled by the electrolyte concentration (potassium hydroxide, KOH), was varied by varying the electrolyte concentration from 0wt% to 45wt% KOH.  The effect of discharged rates (C-rates) was studied from 1C to C/20 rate in 30 wt% KOH electrolyte. As MnO2 is not conductive, graphite was added to improve the electronic conductivity. The effect of graphite content was studied on the discharge behavior. This research was able to find the best electrolyte concentration, electrode composition and studied the effect of C-rates on the discharge capacity.


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