A review of carbon nanotubes in modern electrochemical energy storage

The quest for sustainable energy storage solutions is more critical than ever, with the rise in global energy demand and the urgency of transition from fossil fuels to renewable sources. Carbon nanotubes (CNTs), with their exceptional electrical conductivity and structural integrity, are at the forefront of this endeavor, offering promising ways for the advance of electrochemical energy storage (EES) devices. This review provides an analysis of the synthesis, properties, and applications of CNTs in the context of EES. We explore the evolution of CNT synthesis methods, including arc discharge, laser ablation, and chemical vapor deposition, and highlight the recent developments in metal-organic framework-derived CNTs and a novel CNT aggregate with a three-dimensional ordered macroporous structure. We also examine the role of CNTs in improving the performance of various EES devices such as lithium-ion, lithium-metal, lithium-sulfur, sodium, and flexible batteries as well as supercapacitors. We underscore the challenges that remain, including the scalability of CNT synthesis and the integration of CNTs in electrode materials, and propose potential solutions and future research directions. The review presents a forward-looking perspective on the pivotal role of CNTs in shaping the future of sustainable EES technologies.