Flexible Sub-Micro Carbon [email protected] as Anodes for Potassium-Ion Batteries

Potassium-ion batteries (KIBs) with potential cost benefits are a promising alternative to lithium-ion batteries (LIBs). However, because of the large radius of K+, current anode materials usually undergo large volumetric expansion and structural collapse during the charge-discharge process. Self-supporting carbon nanotubes encapsulated in sub-micro carbon fiber ([email protected]) are utilized as the KIB anode in this study. The [email protected] anode exhibits high specific capacity, good rate performance, and cycling stability. The [email protected] electrode has specific capacities of 236 mAh g–1 at 0.1 C and 108 mAh g–1 at 5 C and maintains over 193 mAh g–1 after 300 cycles at 1 C. Furthermore, a combined capacitive and diffusion-controlled K+ storage mechanism is proposed on the basis of the investigation using in situ Raman and quantitative analyses. By coupling the [email protected] anode with the K0.3MnO2 cathode, a pouch cell with good flexibility delivers a capacity of 74.0 mAh g–1 at 20 mA g–1. This work is expected to promote the application of KIBs in wearable electronics