Potassium-ion batteries (PIBs) are of academic and economic significance, but still limited by the lack of highly active electrode materials for de-/intercalation of large-radius K ions. Herein, an interconnected nitrogen/sulfur co-doped carbon nanosheep bundle (N/S-CSB) was proposed as the potassium ions storage material. The rich co-doping of nitrogen/sulfur of N/S-CNB with three-dimensional hierarchical bundled array structure yields distensible interlayer spaces to buffer the volume expansion during K⁺ insertion/extraction, offers more electrochemical active sites to obtain a high specific capacity, and provides efficient channels for fast ion/electron transports. Therefore, the N/S-CSB anode achieved high reversible specific capacity of 365 mAh/g obtained at 50 mA/g after 200 cycles with a coulombic efficiency (CE) close to 100%, high rate performance and long cycle stability. Moreover, the in-situ Raman spectra indicated outstanding reaction kinetics of as-prepared N/S-CSB anode.

Commercial Cu and Al current collectors for lithium-ion batteries (LIBs) possess high electrical conductivity, suitable chemical and electrochemical stability. However, the relatively flat surface of traditional current collectors causes weak bonding strength and poor electrochemical contact between current collectors and electrode materials, resulting in potential detachment of active materials and rapid capacity degradation during extended cycling. Here, we report an ultrafast femtosecond laser strategy to manufacture hierarchical micro/nanostructures on commercial Al and Cu foils as current collectors for high-performance LIBs. The hierarchically micro/nanostructured current collectors (HMNCCs) with high surface area and roughness offer strong adhesion to active materials, fast electronic delivery of entire electrodes, significantly improving reversible capacities and cyclic stability of HMNCCs based LIBs. Consequently, LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) cathode with Al HMNCC generated a high reversible capacity after 200 cycles (25% higher than that of cathode with Al CC). Besides, graphite anode with Cu HMNCC also maintained prominent reversible capacity even after 600 cycles. Moreover, the full cell assembled by graphite anode with Cu HMNCC and NCM523 cathode with Al HMNCC achieved high reversible capacity and remarkable cycling stability under industrial-grade mass loading. This study provides promising candidate for achieving high-performance LIBs current collectors.

Potassium-based dual ion batteries (KDIBs) have attracted significant attention owing to high working voltage, high safety, low processing cost, and environmental friendliness. Nevertheless, one great challenge for practical KDIBs is to develop suitable anode materials with high specific capacity. Herein, we report an architecture of hierarchically porous antimony nanoparticles/carbon nanofibers (HPSbCNFs) as flexible, free-standing anode for high-performance KDIBs. The HPSbCNFs with hierarchically porous structure, and high-content nitrogen doping, not only offer sufficient free space to tolerate the repetitive volume expansion of Sb nanoparticles during long-term cycling, but also greatly facilitate the transport of electrons and ions within electrode, ensuring high material utilization ratio. Thus, the KDIBs, constituted by HPSbCNFs-700 (calcined at 700 °C) anode and graphite cathode, exhibited a high reversible capacity of 440 mAh g⁻¹ with high discharge medium voltage of 4.5 V at a specific current of 200 mA g⁻¹ (the highest capacity for all KDIBs normalized by the mass of the anode), and excellent cyclic life. Outstanding electrochemical reversibility of the KDIBs was further demonstrated by ex situ XRD, ex situ Raman spectrum, and HRTEM. These results suggest the as-designed HPSbCNFs-700 with high-capacity and long-term cycling stability is a promising anode material for high-performance KDIBs.