Energy storage devices containing a carbon nanotube aerogel and methods for making the same

Conventional rechargeable batteries, such as lithium-ion batteries, are somewhat limited in their energy storage density. Sulfur-based batteries can provide improved energy storage density, but their use can be hampered by sulfur's low electrical conductivity. Energy storage devices, particularly batteries, can have a first electrode that includes a carbon nanotube aerogel, and an electroactive material containing sulfur that is incorporated in the carbon nanotube aerogel. Methods for forming an energy storage device can include incorporating an electroactive material containing sulfur in a carbon nanotube aerogel, compressing the carbon nanotube aerogel to form a compressed carbon nanotube aerogel, and disposing a first electrode containing the compressed carbon nanotube aerogel and the electroactive material in an electrolyte with a second electrode and a plurality of lithium ions, such that a separator material permeable to the lithium ions is between the first electrode and the second electrode.