Pseudohexagonal Nb 2 O 5 Anodes for Fast-Charging Potassium-Ion Batteries.

High-rate batteries will play a vital role in future energy storage systems, yet while good progress is being made in the development of high-rate lithium-ion batteries, there is less progress with post-lithium-ion chemistry. In this study, we demonstrate that pseudohexagonal Nb 2 O 5 (TT-Nb 2 O 5 ) can offer a high specific capacity (179 mAh g -1 ∼ 0.3C), good lifetime, and an excellent rate performance (72 mAh g -1 at ∼15C) in potassium-ion batteries (KIBs), when it is composited with a highly conductive carbon framework; this is the first reported investigation of TT-Nb 2 O 5 for KIBs. Specifically, multiwalled carbon nanotubes are strongly tethered to Nb 2 O 5 via glucose-derived carbon (Nb 2 O 5 @CNT) by a one-step hydrothermal method, which results in highly conductive and porous needle-like structures. This work therefore offers a route for the scalable production of a viable KIB anode material and hence improves the feasibility of fast-charging KIBs for future applications.