Carbon Allotrope-based Materials as Supercapacitors
Abstract
Carbon allotropes, for instance, graphene, carbon nanotubes (CNTs), and activated carbon (AC), along with hybrid structures, have appeared as promising electrode materials for supercapacitors owing to their distinct properties and versatile structures. This chapter examines recent developments in carbon allotrope-based materials for supercapacitor applications, focusing on significant advances in material design, synthesis, and performance optimization. Significant advancements in carbon allotrope-based supercapacitors have been discovered across a full extent of materials. Graphene-based electrodes have exceptional specific capacitances up to 392 F g−1 at 5 mV s−1 scan rate, while functionalized or doped CNT electrodes have improved specific surface areas of up to 1300 m2 g−1, specific capacitances of 180 F g−1, along with power densities of 210 kW kg−1. Advanced activation and templating methods have enabled activated carbon materials to achieve tunable pore structures and high specific surface areas, thereby improving capacitive performance. Hybrid structures that combine different carbon allotropes or incorporate pseudocapacitive materials have shown synergistic effects, as demonstrated by AC–MoS2 composites with an exact capacitance of 216 F g−1 along with an energy density of 6.2 W h kg−1. Furthermore, heteroatom doping, particularly with nitrogen, has been shown to significantly improve electrochemical performance, with N-doped CNTs achieving a specific capacitance of 215 F g−1 at 0.2 A g−1, which is 3.1 times better than that of pristine CNTs. These developments demonstrate the enormous potential of carbon allotrope-based materials in advancing supercapacitor technology. This chapter also discusses current challenges such as scalability, cost-effectiveness, and long-term stability, as well as future research directions for improving carbon allotrope-based materials in supercapacitor applications.