High-voltage liquid-electrolyte microbatteries composed of serial unit cells defined by the surface-tension effect

Abstract

We present high-voltage liquid-electrolyte microbatteries, inspired by the high-voltage generation mechanism of electric eels using serially connected unit cells. Compared to the previous stacked micropower sources, the present microbatteries achieve easy liquid-electrolyte filling with reduced charging time. In order to isolate each cell, we purge air into the liquid electrolyte filled in a channel layer, with three types of surface-tension valves (cell-front, outlet and cell-end valves). We design and characterize four different prototypes of microbatteries: C1, C10, C20 and C40, composed of the serial interconnection of 1, 10, 20 and 40 unit cells, respectively. In the experimental study, we measure threshold pressures of the three surface tension valves of cell-front, outlet and cell-end valves as 460 +/- 47, 1000 +/- 53 and 2800 +/- 170 Pa, respectively. The average charging time of C40 has been measured as 26.8 +/- 4.9 s where the electrolyte and air flow rates are 100 and 200 mu 1 min(-1), respectively. The prototypes of the microbattery C40 show a maximum voltage of 12 V, a maximum power density of 110 mu W cm(-2) and a maximum power capacity of 2.1 mu Ah cm(-2). The present microbatteries have the potential for application in high-voltage portable power sources.