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

Abstract 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.