Investigating K<sup>+</sup> Storage Behavior of Highly Graphitized Carbon Fibers as Anodes for a Potassium-Ion Battery.

Gao, Chongwei; Wang, Xunan; Zhu, Yixin; Zhai, Dengyun; Kang, Feiyu · Nano Lett · 2023

basic_science · Level V

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Abstract

Many problems of potassium-ion batteries (PIBs) are hidden under a low mass load of the active material. However, developing research based on areal capacity is challenging for PIBs, due to the lack of an anode capable of delivering a stable capacity of more than 1 mAh cm<sup>-2</sup>. This work investigates the K<sup>+</sup> storage behavior of highly graphitized carbon fibers (HG-CF), which exhibit automatic structural adjustments to mitigate voltage polarization. The created defects and residual K<sup>+</sup> in the structure favor the reversible insertion/deinsertion of K<sup>+</sup>. HG-GF after structural adjustment realizes a capacity of 2 mAh (1.13 cm<sup>-2</sup>) without K deposition and a stable cyclic stability (>500 h). <i>In situ</i> X-ray diffraction and <i>in situ</i> Raman spectra were used to detect defect formation and structural evolution during cycles. This work demonstrates the feasibility of HG-GF as an anode for PIBs and provides a suitable anode for further research of PIBs based on areal capacity.