Carbon Nanotubes for Electrochemical Capacitors

In recent years, much research has been conducted in the application of carbon nanotubes (CNTs) in supercapacitors. Considering that the performance of supercapacitors largely depends more on the electrode architectures than on the intrinsic properties of CNTs, especially in the case of hybrid electrodes whose synergetic effect plays a crucial role, the designing (or controlling) of CNT architectures is thus of great importance. Because architectures with suitable design can provide a highly conductive network with highly accessible specific surface area (SSA) and proper pore size distribution (PSD), which are crucial for charge transportation and ion diffusion, a review focusing more on the electrode architectures is necessary. This chapter focuses particularly on the elaboration of designing and controlling the architecture/structure of CNT-based electrodes, as well as their effects on material properties such as effective SSA and PSD as well as the device performance of electrochemical capacitors (ECs). After a brief introduction of energy storage mechanisms of ECs and the effect of PSD, the development and challenges for the electrode based on CNTs and nanocarbon hybrid architectures are discussed in detail.