Protein-derived 3D amorphous carbon with N, O doping as high rate and long lifespan anode for potassium ion batteries

Abstract Owing to the abundant resource and tunable structure, amorphous carbon materials have been widely studied as anode for alkali-metal ion batteries. However, it is still a huge space to promote their electrochemical performance for potassium ion batteries (PIBs), especially rate capability, because of the sluggish kinetics of potassium ions. In this work, 3D amorphous carbon with nitrogen and oxygen dual doping (N/O-3DC) is elaborately designed and facilely synthesized for high performance PIBs. Benefit from the synergistic effect of structural advantages, N/O-3DC electrode delivers a high reversible capacity (345 mA h g−1 at 0.03 A g−1), excellent rate performance (132 mA h g−1 at 9.6 A g−1) and ultralong lifespan (0.02% capacity decay per cycle over 1000 cycles at 3 A g−1). Combined with control experiment and structural characterization, it demonstrates the interaction between introduction of heteroatoms, construction of 3D open pore network and tailored microstructure, obtaining more active sites and enlarged interlayer spacing. Kinetic analysis and density functional theory calculations reveal dual N/O doping can not only facilitate the adsorption/desorption of K+ and elevate electronic conductivity, but also reduce energy barrier for K+ diffusion, hence promote the reaction kinetics. This work presents an appealing development of high performance carbon anode with multi-strategy coupling for PIBs.