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.
Highlights
Research on new energy storage technologies has received great attention due to the inevitable depletion of fossil fuels and the need to reduce CO2 emissions to realize sustainable economic and societal growth
During the thermal decomposition of FeS2, it was progressively transformed into Fe1−xS, and the crystalline grains became porous as sulfur gas escaped, which was reported in a previous investigation of the decomposition process and is described by the following equation[46]
The MCs, with an estimated formula of Fe9S10, were tested as an anode in KIBs, and this is the first demonstration of pyrrhotite as an electrode material in the field
Summary
Research on new energy storage technologies has received great attention due to the inevitable depletion of fossil fuels and the need to reduce CO2 emissions to realize sustainable economic and societal growth. The last few years have seen rapidly increasing research activities on Na-ion and K-ion batteries (NIBs and KIBs) that use earth-abundant elements[1,2,3,4,5]. Materials are examined for their feasibility to serve NIBs and KIBs as alternatives to Li-ion batteries (LIBs), which could mitigate the potential supply risks and price increases of the current LIB industry. These benefits highlight the commercial prospect of KIBs, and as a result, it is of utmost urgency to develop this exciting type of battery by exploring electrode materials that can store K+. The major barrier to developing KIBs is the large size of K+ (K+/Na+/Li+: 152/116/90 pm) because it causes difficulties of K+ insertion and diffusion. An effective approach to overcome this barrier is to utilize crystal structures that have directional K+ diffusion pathways
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