Synergistic Enhancement of Li-O2 Battery Capacity and Cycle Life Using Carbon Nanochain/Multiwall Carbon Nanotube Composites

Multiwalled carbon nanotube (MWCNT) Li-O2 cathodes can achieve high gravimetric capacity. However, the macropores of these cathodes require a relatively large mass of electrolyte to fill, resulting in lower true gravimetric and volumetric capacities. Here we report a simple method to incorporate a mesoporous material, carbon nanochains (CNCs), into the macropores of MWCNTs, resulting in composite cathodes that fully utilize their pore structure to store Li2O2 product. The composite cathodes exhibit additional mesopores with an average diameter of ~100 nm. This results in dramatic increases in true gravimetric (21% to 870 mAh/g) and volumetric (>200% to 5664 mAh/cm3) capacities. The composite cathodes demonstrate improved electrochemical reversibility, increasing the cycle life by more than 50%.