Flexible Supercapacitors Based on Two-Dimensional Materials

As an alternative to batteries, supercapacitors were created after capacitors had been developed for more than 100 years. This chapter introduces the flexible supercapacitors based on 2D materials. It demonstrates that the conductivity of electrode materials plays a vital role in the performance of flexible supercapacitors. In electric double-layer supercapacitors (EDLCs), the electrical energy is directly stored through an electrostatic way, as positive and negative charges store on the surface of two electrodes. The advantages of EDLCs and pseudocapacitors lies in the asymmetric supercapacitors, which are constitutive of pseudocapacitive materials in one electrode and electric double-layer capacitive materials in the other electrode. For practical application, it is crucial to develop flexible supercapacitors with higher energy density, high power density, and excellent cycling stability. Numerous materials (from 0D to 3D) have been developed as electrode materials of flexible supercapacitors. The chapter summarizes the recent developments in flexible supercapacitors using nanomaterials of different morphologies.