A review on applications and challenges of carbon nanotubes in lithium-ion battery

Carbon nanotubes (CNTs) have many excellent properties that make them ideally suited for use in lithium-ion batteries (LIBs). In this review, the recent research on applications of CNTs in LIBs, including their usage as freestanding anodes, conductive additives, and current collectors, are discussed. Challenges, strategies, and progress are analyzed by selecting typical examples. Particularly, when CNTs are used with relatively large mass fractions, the relevant interfacial electrochemistry in such a CNT-based electrode, which dictates the quality of the resulting solid–electrolyte interface, becomes a concern. Hence, in this review the different lithium-ion adsorption and insertion mechanisms inside and outside of CNTs are compared; the influence of not only CNT structural features (including their length, defect density, diameter, and wall thickness) but also the electrolyte composition on the solid–electrolyte interfacial reactions is analyzed in detail. Strategies to optimize the solid–solid interface between CNTs and the other solid components in various composite electrodes are also covered. By emphasizing the importance of such a structure–performance relationship, the merits and weaknesses of various applications of CNTs in various advanced LIBs are clarified.