Potassium ion batteries (KIB) have been considered as helpful alternative energy storage devices owing to the low-cost and abundant potassium sources. However, it is a critical challenge to explore suitable anode materials and electrolytes for adapting large radius and high activity of K ions. In this study, a novel FeSe2 nanoparticle embedded in 3D honeycomb-like N-doped carbon architectures (FeSe2-NC) is synthesized through a simple solid-state strategy. Such unique architecture structure can not only provide a high-way for electron and K+ transport, but also effectively alleviate volume variation during long-term K+ intercalation/deintercalation process. Hence, FeSe2-NC as anode materials for KIB display a high discharge capacity of 460 mAh g−1 at 100 mA g−1 and excellent long-term cycling stability even at a high current density of 2 A g−1. Beyond the electrochemical performance, it is found that storage K+ of FeSe2-NC represents a conversion mechanism during discharge/charge in KIB. Furthermore, regulating the electrolyte salts via replacing potassium bis(fluorosulfonyl)imide (KFSI) electrolyte with potassium hexafluorophosphate (KPF6) electrolyte can form a more uniform and robust solid electrolyte interphase film, which be responsible for the enhanced electrochemical performance. Therefore, it is helpful to understand the fundamentals of FeSe2-NC and promote the practical application of KIB.
Bibliographical noteKAUST Repository Item: Exported on 2021-02-21
Acknowledgements: This work is support financially by the National Natural Science Foundation of China (Nos. 51502256, 51602101), Hunan Provincial Natural Scientific Foundation of China (Nos. 2017JJ3297, 2018JJ3144), Scientific Research Projects of Hunan Provincial Strategic Emerging Industries (No. 2016GK4030), China Postdoctoral Science Foundation (No. 2014M552142), Hunan Provincial Education Office Foundation of China (Nos. 17C1523, 19A261) and Scientific Research Fund of Xiangtan University (Nos. 2018HJYH08; 2015SEP03; 13QDZ30; 2014XZX07; 2018ZKKF03).