Pouch Type Cells for Practical Evaluation and Application of Large-Scale Li-Air Batteries

Abstract

Thanks to high theoretical specific capacity and energy density, Li-air batteries are considered as candidates for next-generation battery systems in place of conventional Li-ion batteries for advanced applications such as electric vehicles (EV).1-3 However, low energy efficiency, poor cycle life and Li-metal safety issues make the use of Li-air batteries yet impractical. In addition, actual cell capacities are very low and, since only small-scale electrodes are currently tested, it is hard to predict the properties of large-size electrodes and cells, thus evaluating and judging real practical challenges related to this battery technology. Here, we report on fabrication, operation and evaluation of pouch-type Li-air cells using 3×5 cm2 sized electrodes, in which we intend deal with higher capacity (mAh) of the electrodes, compared to most previous studies in the field. With the relatively large-sized cells, operating at high current density and capacity, we could recognize some remarkable problems that may not be significant in small cells. In relatively large cells as those explored in this work issues related to non-uniform current distribution, mechanical and electronic integrity of electrodes are much more influencing compared to small cells. Hence, problems such as lithium dendrites formation and non-uniform deposition of oxygen reduction product become severe. This study can help to determine which parameters are the most important for developing practical Li-air batteries.