Constructing Carbon Nanobubbles with Boron Doping as Advanced Anode for Realizing Unprecedently Ultrafast Potassium Ion Storage

Abstract

Carbonaceous material with favorable K+ intercalation feature is considered as a compelling anode for potassium‐ion batteries (PIBs). However, the inferior rate performance and cycling stability impede their large‐scale application. Here, a facile template method is utilized to synthesize boron doping carbon nanobubbles (BCNBs). The incorporation of boron into the carbon structure introduces abundant defective sites and improves conductivity, facilitating both the intercalation‐controlled and capacitive‐controlled capacities. Moreover, theoretical calculation proves that boron doping can effectively improve the conductivity and facilitate electrochemical reversibility in PIBs. Correspondingly, the designed BCNBs anode delivers a high specific capacity (464 mAh g−1 at 0.05 A g−1) with an extraordinary rate performance (85.7 mAh g−1 at 50 A g−1), and retains a considerable capacity retention (95.2% relative to the 100th charge after 2000 cycles). Besides, the strategy of pre‐forming stable artificial inorganic solid electrolyte interface effectively realizes high initial coulombic efficiency of 79.0% for BCNBs. Impressively, a dual‐carbon potassium‐ion capacitor coupling BCNBs anode displays a high energy density (177.8 Wh kg−1). This work not only shows great potential for utilizing heteroatom‐doping strategy to boost the potassium ion storage but also paves the way for designing high‐energy/power storage devices.