Energy storage and generation from thermopower waves: covalently functionalized thermal and electrical conduits

We have demonstrated through simulation and experiment that the nonlinear coupling between an exothermic chemical reaction and a nanowire or nanotube with large axial heat conduction accelerates the thermal reaction wave along the nano-conduit. The thermal conduit rapidly transports energy to unreacted fuel regions, and the reaction wave induces a concomitant thermopower wave of high power density, producing electrical current in the same direction. At up to 7 W/g, this can be substantially larger than the power density offered by current micro-scale power sources (e.g. fuel cells, batteries) and even about seven times greater than that of commercial Li-ion batteries. MEMS devices and wireless sensor networks would benefit from such high power density sources to enable functions such as communications and acceleration hampered by present power sources. Recently, we have covalently attached energetic molecules of mono-, di-, and trinitrobenzenes to single-walled carbon nanotubes via diazonium chemistry. Although covalent functionalization introduces defects that can scatter electrons and phonons, thermopower waves can still rapidly propagate and produce electricity on these decorated nanotubes. Differential scanning calorimetry confirms that the energetic molecules release heat, but thermopower waves require additional fuel adsorbed on the nanotubes to propagate.