Three-Dimensional Carbon Nanotube/Transition-Metal Oxide Sponges as Composite Electrodes with Enhanced Electrochemical Performance

Innovative three-dimensional (3D) carbon nanotube (CNT)/transition-metal oxide (TMO) sponge electrodes are synthesized by freeze-drying and calcination processes. The high specific surface area and porosity of the CNT sponge provide more attachment sites for the TMO nanoparticles, a larger contact area with electrolytes, and more space for volume expansion, which enable the CNT/TMO sponge electrodes to exhibit ultrahigh reversible capacity and excellent cycling stability. The continuous CNT network in this new type of electrode can fully satisfy fast electron-transfer kinetics; thus, excellent rate performance is realized. Furthermore, the unique structural characteristics of the 3D CNT sponge make it suitable for making almost all kinds of CNT/TMO composite electrodes, reflecting its versatility for use in many battery systems