Coral-like and binder-free carbon nanowires for potassium dual-ion batteries with superior rate capability and long-term cycling life

Owing to the advantages of high operating voltage, environmental benignity, and low cost, potassium-based dual-ion batteries (KDIBs) have been considered as a potential candidate for large-scale energy storage. However, KDIBs generally suffer from poor cycling performance and unsatisfied capacity, and inactive components of conductive agents, binders, and current collector further lower their overall capacity. Herein, we prepare coral-like carbon nanowires (CCNWs) doped with nitrogen as a binder-free anode material for K+-ion storage, in which the unique coral-like porous nanostructure and amorphous/short-range-ordered composite feature are conducive to enhancing the structural stability, to facilitating the ion transfer and to boosting the full utilization of active sites during potassiation/de-potassiation process. As a result, the CCNW anode possesses a hybrid K+-storage mechanism of diffusive behavior and capacitive adsorption, and stably delivers a high capacity of 276 mAh g-1 at 50 mA g-1, good rate capability up to 2 A g-1, and long-term cycling stability with 93% capacity retention after 2000 cycles at 1 A g-1. Further, assembling this CCNW anode with an environmentally benign expanded graphite (EG) cathode yields a proof-of-concept KDIB, which shows a high specific capacity of 134.4 mAh g-1 at 100 mA g-1, excellent rate capability of 106.5 mAh g-1 at 1 A g-1, and long-term cycling stability over 1000 cycles with negligible capacity loss. This study provides a feasible approach to developing high-performance anodes for potassium-based energy storage devices. (c) 2021 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Researchers developed coral-like carbon nanowires doped with nitrogen as a binder-free anode material for potassium-based dual-ion batteries. The unique porous nanostructure and amorphous/short-range-ordered composite feature of the carbon nanowires enhance structural stability, facilitate ion transfer, and improve active site utilization. The anode exhibits diffusive behavior and capacitive adsorption, delivering a high capacity of 276 mAh g-1 at 50 mA g-1, good rate capability up to 2 A g-1, and long-term cycling stability with 93% capacity retention after 2000 cycles at 1 A g-1. Assembling this anode with an environmentally benign cathode yields a potassium-based dual-ion battery with high specific capacity, excellent rate capability, and long-term cycling stability.