Improving Performance and Cyclability of Printed Flexible Zinc-Air Batteries Using Carbopol Gel Electrolyte

Thursday, 1 June 2017: 11:40
Grand Salon C - Section 18 (Hilton New Orleans Riverside)
S. Chaduang, W. Lao-atiman, and S. Kheawhom (Chulalongkorn University)
Rechargeable batteries are critical as power sources used in various applications such as electrical vehicles, grid-scale storages and portable electronics. Zinc-air batteries are attractive because these batteries use raw materials which are relatively low cost, have low toxicity and are environmentally friendly but exhibit high specific energy density. Moreover, zinc is relatively safe and stable. However, under repeated charging and recharging, zinc anodes undergo a dendrite formation problem. Zinc anode dissolves into electrolyte during discharge and deposited back during recharge. During recharge, dendritic zinc is formed easily and can cause internal short circuits resulting in shortening cycle life of the batteries.

Gel polymer electrolyte have been extensively studied for their ability to improve performance of the batteries in various ways. Specifically, gel polymer electrolytes have shown promise as candidates to suppress zinc dendrite growth. However, the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials.

Thus, this work aims at investigating and discussing the role of carbopol gel electrolyte in rechargeable flexible printed zinc-air batteries. The rechargeable zinc-air batteries are fabricated using an inexpensive screen-printing technique. The anode and cathode current collectors are printed using commercial nanosilver conductive ink on a polyethylene terephthalate (PET) substrate and polytetrafluoroethylene (PTFE) laminated with polypropylene (PP) membrane, respectively. Nylon membrane is used as the separator. Air cathodes are fabricated using blended graphite powder with MnO2 and sodium silicate. Anode electrodes are fabricated using formulations consisting of zinc, graphite powder and sodium silicate.

Carbopol gel electrolyte is investigated in order to elucidate the nature of the different microstructures of the gel in relation to the concentration of carbopol. In addition, the effects of the concentration of carbopol (0.1–5 wt.%) on ionic conductivity is investigated. Electrochemical impedance spectroscopy (EIS) is employed to investigate the electrochemical properties of the gel electrolyte. Moreover, the effects of the concentration of carbopol on polarization curve, discharge-recharge profile of the batteries at various current densities are analyzed. The morphology of the anodes and its electrochemical parameters are studied as a function of discharge-recharge cycle. The results showed that carbopol gel electrolyte significantly inhibit the formation of dendrites, and significantly increasing the number of achievable cycles.