Making Better Sodium-Ion Batteries

The performance of sodium-ion batteries can be markedly improved by substituting common carbon-based anode materials with a templated carbon featuring pores and channels on the micro- and nanometer scales, according to researchers in Germany (Energy Environ. Sci., DOI: 10.1039/c1ee01744f). Similarities between sodium- and lithium-ion electrochemistry coupled with sodium’s abundance relative to lithium have motivated researchers to develop experimental sodium-ion cells. Such batteries could provide a low-cost way to store electricity generated by wind turbines and solar farms. Until now, however, sodium-ion batteries have exhibited weak charge-discharge behavior except when operated at high temperatures (>60 °C)—an indication of sluggish sodium-storage kinetics in standard carbon anodes. To speed up ion transport in and out of the anode, Sebastian Wenzel, Philipp Adelhelm, and coworkers at Justus Liebig University, Giessen, used porous silica as a template to prepare carbon with interconnected pores in two size ranges. Battery tests comparing the templated carbon anode with ones made from a series of commercial porous and reference carbons show that the new material provides improved charge-storage capacity and recyclability and a 15-fold increase in room-temperature charge-discharge rates.