Tailoring Extrinsic Pseudocapacitance of Bi Nanodots Confined in Multichannel Hollow Carbon Nanofibers for Efficient Chloride Capture

ABSTRACT The trade‐off among energy density, power density, and cycling stability has remained an enduring challenge in electrodes for chloride ion (Cl ⁻ ) capture. Tailoring the enhanced extrinsic pseudocapacitance by nanoconfinement manipulation of battery materials is expected to achieve this balance, as it improves diffusion kinetics and lifetime while maintaining the high energy density. Herein, Bi nanodots in situ anchored within multichannel carbon nanofibers (Bi@MCNF) are designed by nanoconfinement engineering for efficient Cl ⁻ capture. The extrinsic pseudocapacitance and shortened ion diffusion paths of the Bi nanoarchitecture, together with the two “highways” of conductive carbon skeleton and hollow channels provided by MCNF for electron transport and ion migration, contribute to the fast kinetics (21.41 mg _Cl ⁻ g ⁻¹ min ⁻¹ ). The 3D carbon skeleton involving void spaces disperses and anchors the Bi nanodots to maximize the energy density for the high capacity of 235.55 mg _Cl ⁻ g ⁻¹ . The nano effect, hollow structure, and carbon encapsulation of Bi@MCNF alleviate the structural stress during the conversion, retaining 90.89% of the capacity in 100 cycles. This work pays unprecedented attention to the extrinsic pseudocapacitance of Cl ⁻ battery materials and further sheds new light on improving power density and cycle life in the broader field of energy storage.