Recently, K-ion batteries (KIBs) have attracted attention for potential applications in next-generation energy storage devices principally on the account of their abundancy and lower cost. Herein, for the first time, we report an anatase TiO 2 -derived Magnéli phase Ti 6 O 11 as a novel anode material for KIBs. We incorporate pristine carbon nanotube (CNT) on the TiO 2 host materials due to the low electronic conductivity of the host materials. TiO 2 transformed to Magnéli phase Ti 6 O 11 after the first insertion/deinsertion of K ions. From the second cycle, Magnéli phase Ti 6 O 11 /CNT composite showed reversible charge/discharge profiles with ∼150 mA h g -1 at 0.05 A g -1 . Ex situ X-ray diffraction and transmission electron microscopy analyses revealed that the charge storage process of Magnéli phase Ti 6 O 11 proceeded via the conversion reaction during potassium ion insertion/deinsertion. The Magnéli phase Ti 6 O 11 /CNT composite electrode showed long-term cycling life over 500 cycles at 200 mA g -1 , exhibiting a capacity retention of 76% and a high Coulombic efficiency of 99.9%. These salient results presented here provide a novel understanding of the K-ion storage mechanisms in the extensively investigated oxide-based material for Li-ion batteries and Na-ion batteries, shedding light on the development of promising electrode materials for next-generation batteries.
Bibliographical noteFunding Information:
This work was supported by an Energy Efficiency & Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Trade, Industry & Energy (MOTIE) (No. 20172420108590) and the Technology Innovation Program or Industrial Strategic Technology Development Program (10062226, development of flexible hybrid capacitor (0.25 mWh/cm2) composed of graphene-based flexible electrode and gel polymer electrolyte with high electrolyte uptake) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea).
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)