Die Su,Jianping Yang,Qingshui Hong,Min Yang,Jiaxing Wen,Qianfu Wang,Hai Hu,Li Liu,Xiukang Yang
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 TiNbO 4 /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 TiNbO 4 /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.
Yifan Zhang,Laifu Yang,Wenqiang Wang,Gengchao Wang
LiNbO 3 is an intercalation material with high theoretical specific capacity, which is promising for lithium-ion capacitor (LIC) anode. However, the poor charge transfer dynamics makes LiNbO 3 unable to match the capacitive cathode in rate performance and cycle stability, resulting in poor electrochemical performance of the device. Herein, through the integrated process of in-situ nitrogen-doping with polypyrrole as the nitrogen source and hydrothermal deposition, the coaxial heterostructure of ultrafine LiNbO 3 nanoparticles and nitrogen-doped carbon nanotubes (NCNT) was realized. The large lithium-ion accessible surface and the bonding with the conductive channel significantly enhance the pseudocapacitive behavior of LiNbO 3 (capacitance contribution of 78.5% at 1 mV s −1 ). After 1000 cycles at a current density of 2 A g −1 , NCNT@LiNbO 3 still has a specific capacity of 154.9 mAh g −1 (89.8%). Thus, the assembled NCNT@LiNbO 3 //AC devices can charge and discharge up to 10000 cycles at a current density of 2 A g −1 , and the capacity retention rate can still reach 90.3%, and can provide an energy density of 142 Wh kg −1 . This work provides ideas for the interface and structure design of nanocomposite electrode materials.
危险品化学品经营许可证（带存储）