Environmentally friendly high performance Zn-air rechargeable battery using cellulose derivatives: A 3D-printed prototype
Tibor Nagy, Lajos Nagy, Zoltán Erdélyi, E. Baradács, György Deák, Miklós Zsuga, Sándor Kéki
Abstract
In this paper an environmentally friendly high performance prototype of rechargeable Zn-air battery using cellulose based biodegradable matters as additive and diaphragm is reported. During designing we were aspired to construct a heavy metal free cell containing nontoxic, commercially available biodegradable feedstock. The fix cell geometry was granted by 3D-printing. Charging/discharging cycle tests were performed using cotton lattice or cellophane diaphragms separately. The presence of carboxymethyl cellulose sodium salt (CMC-Na, Mn: 90 kDa and 250 kDa with f = 0.7 or f = 1.2 average functionality) additives in the electrolyte was also tested. Significant difference was found between the cells operated with and without additives. Two main benefits of the application of CMC-Na salts were observed: (i) by increasing the viscosity of the electrolyte the rate of evaporization of the water was decreased; (ii) owing to the higher viscosity of the lye and the good chelating agent properties of the carboxyl functional groups more stable cell operation was obtained. Using cotton lattice as diaphragm, 100% Coulomb efficiency was detected during the entire measurement (more than 1000 cycles), while the weight of zinc electrode was constant and its surface remained smooth. Additional cyclic voltammetry tests were also carried out to investigate the electrode processes and the change of the electrode surface was monitored by scanning electron microscopy.