High-Energy-Density Li-O2 Battery at Cell Scale with Folded Cell Structure

As potential successors to intercalation-based battery systems, Li-air batteries have attracted enormous research attention because of their higher theoretical specific energy compared with conventional batteries, in terms of unit of energy per active material mass. However, this unit complicates the estimation of realistically attainable cell-scale energy densities because all other indispensable cell components are excluded. Here, we report Li-O-2 batteries with an ultrathin, customized gas-diffusion layer, highly conductive, stable polymeric ionic-liquid separator, and folded cell structure that reduce the volume and mass of multiple cell components. A complete cell-scale specific energy and energy density of 1,214 Wh kg(cell)(-1) and 896 Wh L-cell(-1), respectively, were experimentally achieved. Cell-scale electrochemical phenomena were simulated using a multi-physics model that included the oxygen flow caused by the cathode reaction, dynamic porosity changes, and resistance increase during Li2O2 formation. Both the cell geometry and cathode composition dramatically affected the cell's capacity.