Self‐Assembled FeSe2 Microspheres with High‐Rate Capability and Long‐Term Stability as Anode Material for Sodium‐ and Potassium‐Ion Batteries

• Published in: Chemistry : a European journal 2021-02, Vol.27 (11), p.3745-3752
• Main Authors: Xin, Wen, Chen, Nan, Wei, Zhixuan, Wang, Chunzhong, Chen, Gang, Du, Fei
• Format: Article
• Language: English
• Subjects: anode materials; Anodes; Batteries; Carbonaceous materials; Chemistry; Diffusion rate; Electrochemical analysis; Electrochemistry; Electrode materials; high-rate capability; Lithium; Lithium-ion batteries; Microspheres; Morphology; Potassium; Rechargeable batteries; Sodium; Storage capacity; transition metal selenides
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202004069

Sodium‐ and potassium‐ion batteries have attracted intensive attention recently as low‐cost alternatives to lithium‐ion batteries with naturally abundant resources. However, the large ionic radii of Na+ and K+ render their slow mobility, leading to sluggish diffusion in host materials. Herein, hierarchical FeSe2 microspheres assembled by closely packed nano/microrods are rationally designed and synthesized through a facile solvothermal method. Without carbonaceous material incorporation, the electrode delivers a reversible Na+ storage capacity of 559 mA h g−1 at a current rate of 0.1 A g−1 and a remarkable rate performance with a capacity of 525 mA h g−1 at 20 A g−1. As for K+ storage, the FeSe2 anode delivers a high reversible capacity of 393 mA h g−1 at 0.4 A g−1. Even at a high current rate of 5 A g−1, a discharge capacity of 322 mA h g−1 can be achieved, which is among the best high‐rate anodes for K+ storage. The excellent electrochemical performance can be attributed to the favorable morphological structure and the use of an ether‐based electrolyte during cycling. Moreover, quantitative study suggests a strong pseudocapacitive contribution, which boosts fast kinetics and interfacial storage. Microsphere anode materials: Self‐assembled FeSe2 microspheres are synthesized through a facile solvothermal method. The FeSe2 microspheres exhibit superior rate performance and long cycle stability in both sodium‐ and potassium‐ion batteries.