Authors: John Cushman
We create a 1.7 volt, 1/3 amp flow-battery using vanadium-zinc chemistry in two polar immiscible fluids with porous media stabilization. The immiscible fluids are salt water and methanol or ethanol. We use a porous zinc anode with a carbon-cloth current collector and a neutral electrolyte NH4Cl (MeOH) which is lighter than H2O so it sits atop the acidic salt-water cathode electrolyte which consists on Na2SO4 (aq) + H2SO4(aq) +V5+ (aq) with a graphite electrode. A neutral, non-reacting, porous medium is employed to stabilize the system. The porous zinc anode oxidizes with a -0.7 volt potential while the V5+reduces to V4+ at the cathode with a 1.0 volt potential giving a 1.7 volt battery. Current has been measured at 1 ohm resistance to be 0.3 amps. The chemistry is
Anode: Zn (s) + 2(NH4Cl) – 2NH4+ - 2e-→Zn2+Cl2 in methanol
Cathode: 2(VO2)+SO4 (aq)+ NaHSO4 (aq)+ 2H+ + 2e-→ 2[VO2+SO4] (aq) +H2O + NaOH (aq)
The battery can be run with flowing electrolytes so charging is not necessary, or it can be run in stand-alone mode on a charge/discharge cycle.