Biomass bone-derived, N/P-doped hierarchical hard carbon for high-energy potassium-ion batteries

As a potential candidate of current power supply, potassium ion batteries (PIBs) based on biomass-derived porous carbons are endowed with advantages of low cost, improved energy density, high safety, and long cycling lifespan. Herein, endeavors addressing biomass bone-based anodes for PIBs were devoted to enhance the intercalation chemistry of K⁺. Through a direct pyrolysis of biomass chicken bones without adding any activation agent, 3D porous carbon scaffold (3D-HPCS) with hierarchical nanostructure and heteroatoms doping was adopted as PIBs anode to realize excellent rate capability and cycle life. The prepared 3D-HPCS anode exerted an outstanding initial capacity of 470 mA h g⁻¹ as well as a rate capacity of 113 mA h g^-1 at 2.0 C. Meanwhile, it remained 205 mA h g^-1 after 450 cycles at a current density of 0.2 C, which demonstrated superior rate performance and cyclic stability during K⁺ insertion/extraction. The remarkable performances could be mainly attributed to the comprehensively synergistic contributions of increased interlayer spacing, active heteroatom doping, and intricate porous structures of 3D-HPCS electrode, thereby improving electronic conductivity and ion diffusion kinetics.