Journal
ADVANCED FUNCTIONAL MATERIALS
Volume 28, Issue 49, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.201800670
Keywords
cathode materials; K0.5V2O5; layered potassium vanadate; potassium ion batteries
Categories
Funding
- Beihang University
- Thousand Youth Talents Plan of China
- National Basic Research Program of China [2014CB931802]
- 111 Project [B14009]
- National Natural Science Foundation of China [U1663224]
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Nonaqueous potassium ion batteries (KIBs) are one of the emerging electrochemical energy storage technologies due to the abundance of potassium resources, but the difficulties of intercalation of large size K-ions into electrode materials hinder the development of KIBs. Here, a layered potassium vanadate K0.5V2O5 is proposed as a potential cathode material for KIBs. Despite the large size of K-ions, the as-fabricated material is capable of delivering a reversible capacity around 90 mAh g(-1) at 10 mA g(-1) in the voltage range of 1.5-3.8 V (vs K+/K), and also exhibits a fast rate capability with a capacity of 60 mAh g(-1) at 200 mA g(-1) and good cycling stability with 81% capacity retention after 250 cycles at 100 mA g(-1). Ex situ X-ray diffraction and X-ray photoelectron spectroscopy reveal that the layered potassium vanadate exhibits a highly stable and reversible structure change with a transition between V4+ and V5+ upon potassiation/depotassiation. Additionally, galvanostatic intermittent titration technique results show that the kinetics of potassiation/depotassiation is mainly determined by K-ion diffusion in the active material. The present study may open up further exploration of potassium vanadates and other layered transition metal oxides in the field of KIBs.
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