Dear Mukund Vadrev ,

You incorrectly interpret anode-cathode (positive-negative). During charge Zinc is cathode, but connected to the minus of external power source (and electrodeposited from solutions if Zn2+ is present, or hydrogen evolution if not), and V2O5 is anode connected to the plus (intercalation reaction of some anions). In opposite case zinc as anode will be dissolved and deposited to V2O5.

2-3 volts? That is too high, the paper only cycles 0.2 - 1.6 V vs Zn. What voltage do you use for discharge? You won't see any Zn2+ intercalation until below 1 V according to the paper.

I think Branimir N. Grgur is correct, you must have the anode and cathode leads switched. Above 1V vs Zn, zinc should plate on your anode (zinc), not V2O5. But if your leads are switched, you could expect to see Zn plating on the V2O5/graphite because your voltage is actually -2 to -3V vs Zn.

Make Zn your anode (black/green wires usually), and V2O5 the cathode (red/white wires usually). Cycle between 0.2 - 1.6 V if you are following the paper. Too high or too low you will break down the electrolyte.

Which Electrolyte you are using? The same one as mentioned in the paper or any non-aqueous electrolyte? Even in non-aqueous electrolytes, 2-3V is too high.

Whoops. .. I connect the zinc to the negative of my power supply and my v2o5+graphite to the positive during charging. I am using zinc sulphate 1molar. When I use 1.25- 1.6 volts, I almost have no current (10ma). When I charge at 2.5-3 volts, atleast the motor (17ma inductive draw) runs for a few minutes. Anything else that could be affecting the intercalaction?

Mukund, how much V2O5 do you use? I am used to using milligrams of material, so 10mA is a lot.

Are you using anything to control voltage during discharge? Or are you letting the battery short circuit through the motor?

What does your charging profile look like? Constant current, constant voltage? When do you end charging? Ideally you would use a CCCP profile with a small current and then hold upper voltage for some time or until current drops below a threshold value.

At 2.5 V to 3V, the current shouldn't be due to zinc intercalation. It can be due to some parasitic reactions. The adviced voltage is between 0.2 V to 1.6 V (1.4 V per cell) . If you would like to use the cell for operating some devices, it is better to connect two 1.4V cells in series so that you will get 2.8 V. From a single aqueous ZIB cell, achieving beyond 2 V seems not reliable.

turned out to be a dodgy power supply connection. Everything is working great now. Thanks. I am charging at 3v now