A novel high pseudo-capacitive contribution anode in K-ion battery: Porous TiNbO4/C nanofibers

Abstract

Pseudo-capacitive materials show long cycling life as anode of K-ion battery (KIBs), yet low specific capacity and poor rate performance. Herein, the porous TiNbO4/C nanofibers (denoted as TNO/C) are synthesized via electro-spinning. Abundant oxygen vacancies and large specific surface area make the sample exudes high specific capacity and good rate performance. After optimizing the calcination temperature, it is found that the porous TiNbO4/C nanofibers at 700 °C (denoted as TNO/C-700) can deliver the specific discharge capacity of 250.4 mAh g−1 in K-ion half cell and demonstrate good cycle stability for 100 cycles in K-ion full cell in 100 mA g−1. Even in 5 A g−1, the discharge capacity of TNO/C-700 electrodes is still 116.7 mAh g−1 at rate performance. Ex-situ XRD results show that this TNO/C-700 electrode is associated with pseudo-capacitive effect and insertion/de-insertion process. The TNO/C-700 electrode exhibits a high pseudo-capacitive contribution, which can reach to 85.0% at 3 mV s−1. This novel high pseudo-capacitive contribution anode material provides more possibilities for the selection in KIBs.