Nanoconfinement of low-conductivity products in rechargeable sodium-air batteries

Abstract

To alleviate the high polarization and short cycle lifetime of rechargeable Na-air batteries, ordered mesoporous carbon (OMC) was synthesized and evaluated as a nanostructured conductive matrix to host low-conductivity products generated during the discharge of Na-air batteries. The OMC had high specific surface area (1544 m(2)/g) and a narrow pore size (2.7 nm), with the voltage polarization of 1.5 V, lower than that of the commonly used Super P carbon black (-1.8 V). Although the carbonate-based electrolyte was decomposed to produce Na2CO3, the OMC cathode allowed reversible formation and decomposition of Na2CO3 and exhibited stable cycling behavior with low polarization for 20 cycles with a delivered capacity of 500 mAh/g at the current density of 100 mA/g.