Root-whisker structured 3D CNTs-CNFs network based on coaxial electrospinning: A free-standing anode in lithium-ion batteries

Highlights: • According to the principles of bionics, a kind of root-whisker structured CNTs-CNFs anode in LIBs was designed. • The CNTs-CNFs anode was synthesized by growing CNTs vertically to the surface of CNFs via a CVD technique. • The CNTs-CNFs anode shows high specific capacity, stable rate performance, and long-term cycling performance. • Based on the coaxial electrospinning strategy, the preparation process was simplified significantly. -- Abstract: A root-whisker structured 3D CNTs-CNFs network was designed to work as a free-standing anode in lithium-ion batteries (LIBs). Nickel catalyst was uniformly dispersed on the surface of carbon nanofibers (CNFs) based on a coaxial electrospun technology followed with a regular carbonization process. After then, carbon nanotubes (CNTs) were grown perpendicular to CNFs surface by chemical vapor deposition (CVD). Just as plants rely on strong roots and whiskers to absorb and transport nutrients from the soil, this 3D CNTs-CNFs network enjoys excellent contact with the electrolyte and outstanding capability to capture lithium ions. Moreover, the interlaced nanostructure provides much shorter and faster transport channels for electrons and ions simultaneously. Consequently, our LIBs assembled with this CNTs-CNFs anode represent remarkable cycling stability (545.7 mAh g^-1 at 100 mA g^-1 after 100 cycles and 316.8 mAh g^-1 at 1 A g^-1 after 1000 cycles) and excellent rate capacity (306.72 mAh g^-1 at 1 A g^-1).