Fabrication and evaluation of a Sri Lankan graphite based rechargeable battery

Abstract

Renewable sources such as solar, wind and tidal have been recognized as suitable low cost and environmental friendly solutions for energy production. To store their energy to meet the continuous demand of power, energy storage devices are of utmost importance. Batteries and capacitors are the two main storage devices use commonly. At present, there is a huge concern over their safety as well as their price. This paper reports about fabrication and evaluation of a Zn and graphite based battery that uses a gel polymer electrolyte (GPE) instead of a liquid electrolyte. Graphite was mixed with polyvinylidenefluoride as a binder in the weight ratio 85 % : 15 %. GPE was consisted with polyvinylidenefluoride, ethylene carbonate, propylene carbonate and zinc trifluoromethanesulfonate. Hot pressed method was used to prepare the GPE. Assembling of the battery was done inside an Ar filled glove box. The open circuit potential was found to be about 1.03 V. Cyclic Voltammetry (CV), Galvanostatic Charge Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) techniques were used to analyse the performance of batteries. The capacity values were satisfactory and the capacity fade over continuous cycling was rather low. With the CV test as well as the GCD, it was noted a sudden drop of capacity initially. But, after some cyclings, the rate of reduction has decreased. It may be due to material stabilization, electrolyte - electrode interface formation. No parasitic effects or resistive layer growth was observed in the impedance plot. Further studies are being carried out to improve the performance further.