Simple and Cost-Effective Method to Increase the Capacity of Carbon Nanotube Sheet Cathodes for Lithium–Air Batteries

Thin sheets for the cathode of lithium–air batteries were prepared from a mixture of long carbon nanotubes and a fibrous carbon with a larger diameter. These sheets were found to have sufficient strength and high inner permeability. The discharge capacity of the sheets tended to increase with the decrease in their gas permeation resistance. The sheet with an optimized structure showed high capacity of 17.7 mAh cm –2 at 0.1 mA cm –2 and a moderate rate performance of 9.3 mAh cm –2 at 0.5 mA cm –2 . Analysis of the sheets after discharging revealed that improving the permeability of the sheets through the introduction of large pores by fibrous carbon addition leads to a significant improvement in cathode performance.