Pyrrhotite Fe1−xS microcubes as a new anode material in potassium-ion batteries

Abstract

Potassium-ion batteries are an emerging energy storage technology that could be a promising alternative to lithium-ion batteries due to the abundance and low cost of potassium. Research on potassium-ion batteries has received considerable attention in recent years. With the progress that has been made, it is important yet challenging to discover electrode materials for potassium-ion batteries. Here, we report pyrrhotite Fe1−xS microcubes as a new anode material for this exciting energy storage technology. The anode delivers a reversible capacity of 418 mAh g−1 with an initial coulombic efficiency of ~70% at 50 mA g−1 and a great rate capability of 123 mAh g−1 at 6 A g−1 as well as good cyclability. Our analysis shows the structural stability of the anode after cycling and reveals surface-dominated K storage at high rates. These merits contribute to the obtained electrochemical performance. Our work may lead to a new class of anode materials based on sulfide chemistry for potassium storage and shed light on the development of new electrochemically active materials for ion storage in a wider range of energy applications.

Carbon-Free Crystal-like Fe1–xS as an Anode for Potassium-Ion Batteries

“…Obviously, numerous glitches are able to be observed on each branch, which may arise from the escape of sulfur gas during the heat treatment. 35 Such a unique structure could provide plentiful contact sites to infiltrate with electrolytes and shortened ion/electron diffusion pathways. The TEM image clearly verifies the crystal-like morphology of the prepared Fe 1−x S (Figure S4).…”

“…Subsequently, the precursor prepared with 36 h of a solvothermal reaction undergoes annealing treatment in an inert atmosphere; the obtained product is called carbon-free crystal-like Fe 1– x S. As shown in Figures f and S3, in comparison to the precursor without annealing, the crystal-like Fe 1– x S basically keeps a similar morphology but displays a hierarchical structure. Obviously, numerous glitches are able to be observed on each branch, which may arise from the escape of sulfur gas during the heat treatment . Such a unique structure could provide plentiful contact sites to infiltrate with electrolytes and shortened ion/electron diffusion pathways.…”

Synthesis of yolk‐shell‐structured iron monosulfide‐carbon microspheres and understanding of their conversion reaction for potassium‐ion storage

“…This could be confirmed by previous reports of other iron sulfides for potassium-ion storage. 33,34 To confirm the phase transition during the initial cycle, ex situ XRD analysis was conducted using disassembled electrodes in the fully discharged and charged states. As presented in Figure S6, at the fully discharged state (0.001 V), the XRD spectrum exhibited broad peaks corresponding to potassium sulfide (K 2 S), whereas metallic Fe phase was not observed because of the low crystallinity and small crystal size.…”

Enhanced Potassium Storage Capability of Two-Dimensional Transition-Metal Chalcogenides Enabled by a Collective Strategy

“…Figure S12 shows the Nyquist plots of MoSe 2 @CNTs and the pure MoSe 2 recorded after 10 and 50 cycles. They consist of a semicircle at high-to-medium frequency ranges and a tail at low-frequency regions, which refer to charge-transfer resistance ( R ct ) and K-ion diffusion. , The impedance data could be fitted by an equivalent circuit shown in the inset of Figure S12. It is evident that the MoSe 2 @CNTs electrode exhibits lower R ct values as compared to the pure MoSe 2 regardless of cycles.…”