Mixed-biomass engineering achieves multi-doped highly-disordered hierarchical flower-like hard carbon for advanced potassium-ion battery

Potassium-ion batteries (PIBs) have emerged as a significant technology for large-scale energy storage. With merits of high abundance, sustainability, and low cost, hard carbons are employed as promising anodes for PIBs, yet distorted carbon lattice induces sluggish conductivity and structural degradation, posing key challenges of low power performance and inferior life span. Here, we proposed a mixed-biomass strategy to design a multi-doped flower-like carbon micro-sphere with major doping of N and trace doping of P and S (NPS-FCM) for advanced PIBs operation. The mixed-biomass engineering achieved inherently rich heteroatoms’ doping and highly disordered hierarchical configuration simultaneously. The NPS-FCM material with expanded lattice spacing, larger specific area, and abundant edge defects and pores, offers robust rate property, and impressive cycle life (1000 cycles with 0.147 ‰ capacity decay per cycle). The potassium-ion full cell (NPS-FCM//PTCDA) was also implemented to show a high median-voltage of 1.78 V and steady cycling. Density functional theory calculation convinced the upgraded electronic conductivity and lowered adsorption energy for potassium storage. This work highlights the importance of mixed-biomass’ cooperation to provide pivotal guidance for sustainable and advanced electrodes for next-generation energy storage.