N-doped carbon nanotube sponges and their excellent lithium storage performances

Abstract Preparation, analysis and lithium storage performance of a series of nitrogen‐doped carbon nanotube sponges (CNX) is presented in this work. The synthesis was performed using an aerosol‐assisted chemical vapor deposition (AACVD) in a bi‐sprayer system by using various carbon and nitrogen precursors made of mixtures of benzylamine with toluene, urea, pyridine and 1,2‐dichlorbenzene, with ferrocene as catalyst. A series of physico‐chemical analysis techniques are used to characterize the composition and the morphology of the obtained materials, and a correlation of these with the lithium storage performances is attempted. The samples reveal an interconnected core‐shell CNX fiber morphology with a CNT‐core surrounded by an amorphous carbon shell. Appealing lithium storage performances are attained, while also considering aspects of safety, low potential, and long‐term cycling stability. The best performing sponges display a high specific capacity (223 mAh g−1) when cycled in a practically relevant voltage window (0.01–1V vs. Li), high first cycle (90%) and long‐term cycling (99.3%) coulombic efficiencies and excellent capacity retention after 1500 cycles. This study further analyses the interplay between the morphology and the physico‐chemistry of nitrogen‐doped carbon nanotube materials for Lithium storage and provides guidelines for future developments.