Flexible Antimony@Carbon Integrated Anode for High-Performance Potassium-Ion Battery

Potassium-ion batteries (KIBs) are considered as promising alternatives to lithium-ion batteries due to the abundant resources, low cost, and low redox potential of K. However, KIBs anode materials suffer challenges owing to the large K+ radius and slow reaction dynamics, which result in low reversible capacity and inferior rate capability. Herein, Sb nanoparticles (about 4 nm) confined in an interconnecting carbon porous nanofibers (Sb@C PNFs) are constructed as flexible integrated KIBs anode. In this architecture, Sb nanoparticles are encapsulated and vessel-like channels are contained in the N-doping carbon porous nanofibers, which are adopted as the continuous 3D conductive framework and current collector. Benefiting from the shortened K+ diffusion distance, efficient electrolyte diffusion passages, and reserved space for holding volume swelling, the flexible Sb@C PNFs integrated electrode exhibits excellent K+ storage behaviors (capacities of 399.7 mAh g(-1) at 0.1 A g(-1) and 208.1 mAh g(-1) at 5.0 A g(-1) are delivered, respectively, and a capacity of 264.0 mAh g(-1) is remained even cycled at 2.0 A g(-1) after 500 cycles), and is among the best anode materials up to date. Moreover, the high reversible alloying and dealloying process between cubic K3Sb and as-formed amorphous Sb in the Sb@C PNFs is confirmed.