Construction of foam-like carbon microspheres with controllable pseudo-graphitic domains: Synergistic enhancement of K-ion adsorption/intercalation storage

Foam-like carbon microspheres (FCMs) with controllable pseudo-graphitic domains were constructed via staged pyrolysis. The preferential pyrolysis of PF engenders a robust “carbon skeleton”, while subsequent pyrolysis of PTFE forms a porous channel architecture, perfectly preserving pseudo-graphitic domains and bringing abundant defects/pores structure. The optimized electrode displays a well-balanced adsorption and intercalation capability, exhibiting a high reversible capacity, outstanding rate/cycle property and superb full cells application. [Display omitted] •Developing a unique staged pyrolysis strategy to tailor foam-like carbon microspheres with controllable pseudo-graphitic domains.•The perfectly preserved pseudo-graphitic domains and created rich defects/pores structures ensures efficient K+ low-voltage intercalation and fast K+ transport.•Achieving a high capacity, outstanding rate property/stability and impressive full-cells performance.•Confirming the “adsorption–intercalation” K-storage mechanism and well-balanced active sites crucial for synergistic enhancement of adsorption/intercalation kinetics. Hard carbon shows promise as a potassium-ion battery (PIB) anode, but its high capacity and rate property are limited by insufficient active sites and poor kinetics. Creating a porous channel structure offers an effective route, but such design often disrupts the development of intercalation sites critical for low-voltage plateau capacity, and may reduce the energy density of full cells. Herein, a staged pyrolysis strategy was developed to tailor foam-like carbon microspheres (FCMs) with controllable pseudo-graphitic domains by exploiting polymer with the temperature difference in pyrolysis. Such tactics perfectly retains abundant pseudo-graphitic domains and creates rich defect/pore structures, ensuring efficient K+ low-voltage intercalation and benefiting fast K+ transport. The optimized electrode exhibits balanced adsorption/intercalation capacity, delivering a large reversible capacity (386.7 mAh g−1 at 0.1C), outstanding rate performance (223.1 mAh g−1 at 4C) and excellent capacity retention (79.2 % over 2000 cycles at 4C). Additionally, the FCM-2//PTCDA full cell submits a high energy density of 198 Wh kg−1 and superb rate property/stability compared to same-type full cells. Tracked K-storage behavior confirmed the “adsorption–intercalation” mechanism and kinetic studies clarified that exact balance of defect, mesopore and pseudo-graphitic ph