Highly porous carbon nanotube air-electrode combined with low-viscosity amide-based electrolyte enabling high-power, high-energy lithium-air batteries

Abstract

Lithium-air batteries (LABs) develop high-energy-density battery storages, but the low-rate capabilities limit their practical applications. This study demonstrates an innovative approach for enhancing the power of LABs by integrating a highly porous carbon nanotube (CNT) air-electrode with a low-viscosity amide-based electrolyte. CNT air-electrodes with high surface area enable high-rate discharges, and increasing the electrode porosity allows for sustained discharges at high rates. Amide-based electrolytes with low viscosity, such as 1 M lithium nitrate (LiNO3) dissolved in N,N-dimethylacetamide (DMA) having a one-sixth viscosity of typical LAB electrolytes based on tetraethyleneglycol dimethylether (TEG) solvent, decreased cathode resistance by half by facilitating oxygen transport, enabling an ever-high current density discharge of 4.0 mA cm−2 to provide a capacity of 4.6 mAh cm−2 under dry air, i.e., ∼21 % oxygen atmosphere. Cell assembly suppressing electrolyte solvent evaporation produced high-power rechargeable LAB cells with a power density of 447 W kg−1, providing 447 Wh kg−1 of energy with respect to the total cell weight. This represents the first case of discharge–charge cycles of LABs with high power output specifically focused on drone hovering. The high-power, high-energy density LABs demonstrated in this study pave the way for developing ultra-lightweight aircraft batteries.