Scientists Develop Fluoroxalate Cathode Material for Potassium-Ion Batteries with Ultra-long Cyclability

Date:13-03-2020   |   【Print】 【close

Potassium-ion batteries (KIBs) are a compelling technology for large-scale energy storage due to their low-cost and large abundance. However, the development of potassium-ion batteries remains in its infancy, mainly hindered by the lack of suitable cathode materials. 

A research group led by Prof. TANG Yongbing and his team members (JI Bifa, Dr. YAO Wenjiao, Dr. ZHENG Yongping etc.) from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences, along with Prof. CHENG Huiming from the Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, proposed a fluoroxalate KFeC2O4F as low-cost, environmental friendly and ultra-stabile cathode for KIBs. 

KFeC2O4F exhibits a distinguished three-dimensional framework with large channels along its three crystallographic axes. During charge and discharge, the intrinsic Fe2+/Fe3+ redox provides electron compensation and K-ions are feasible to move along channels, while the framework experiences a very limited volume change. This explains its outstanding stability in cyclic test. 

In the experiments, KFeC2O4F delivered a capacity of 112 mAh/g at 0.2 A/g, and a capacity retention of 94% is maintained after 2000 cycles, with 0.003% capacity fading per cycle. This is the best cycling performance in the reported KIBs cathodes.  

Coupling this KFeC2O4F cathode with a soft carbon anode yielded a K-ion full cell showed great rate performance and cycling stability for 200 cycles with almost no capacity loss. 

The study entitled “A fluoroxalate cathode material for potassium-ion batteries with ultra-long cyclability” was published online in Nature Communications. 

Figure. Characterization of KFeC2O4F cathode material. (a) Photo of as-prepared crystallites. (b) XRD pattern. (c) Structural analysis. (d) Cyclic performance. (Image by JI Bifa) 

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