Wire-in-Wire TiO 2 /C Nanofibers Free-Standing Anodes for Li-Ion and K-Ion Batteries with Long Cycling Stability and High Capacity

Highlights The unique wire-in-wire structure endows TiO 2 /C nanofibers film with superior mechanical flexibility. The wire-in-wire TiO 2 /C nanofibers (TiO 2 ww/CN) film shows outstanding electrochemical performances as free-standing anodes for Li/K-ion batteries and full cells. The TiO 2 ww/CN film shows an extremely high pseudocapacitance contribution ratio in K-ion batteries.