Tunable 2D tremella-derived carbon nanosheets with enhanced pseudocapacitance behavior for ultrafast potassium-ion storage

The sluggish intercalation kinetics of potassium ions in various anode materials severely hinders the practical application of potassium ion batteries (PIBs) in the field of new energy storage. To overcome this difficulty, we developed a green and recyclable molten-salt (MS) strategy using natural tremella as raw material to construct self-N-doped two-dimensional (2D) tremella-derived carbon nanosheets (TCNs), which possesses large specific surface area (SSA), expanded interlayer spacing and rich defects/active sites. Thanks to the unique 2D nanosheet structure and self-N doping, TCNs800 electrode exhibits superior K+ storage capacity (386.3 mA h g(-1) at 0.1 A g(-1)), ultrafast rate performance (119.7 mA h g(-1) at 2.0 A g(-1)) and long-term cycling stability (122.9 mA h g(-1) with the Coulombic efficiency of near 100% after 1000 cycles). Moreover, detailed electrochemical kinetic analysis shows that the potassium-ion storage mechanism of TCNs800 electrode has enhanced by the pseudocapacitance-controlled behavior. This work proves an effective green and environmentally friendly MS strategy to prepare 2D biomass nanosheet materials, and provides a reference for exploring excellent electrode materials with pseudocapacitance-controlled behavior.