Potassium Prussian Blue Nanoparticles: A Low‐Cost Cathode Material for Potassium‐Ion Batteries

• Published in: Advanced functional materials Vol. 27; no. 4; pp. np - n/a
• Main Authors: Zhang, Chenglin, Xu, Yang, Zhou, Min, Liang, Liying, Dong, Huishuang, Wu, Minghong, Yang, Yi, Lei, Yong
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.01.2017
• Subjects: Abundance; Anodes; Batteries; Carbon; Cathodes; Decay rate; Discharge; Electric batteries; Electric potential; Electrochemistry; Electrode materials; Electrolytes; Energy storage; full‐cells; Iron; Lithium; Low cost; Materials science; Nanoparticles; Nonaqueous electrolytes; Potassium; potassium‐ion batteries; Prussian blue; Structural stability; Sustainability
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201604307

Potassium‐ion batteries (KIBs) in organic electrolytes hold great promise as an electrochemical energy storage technology owing to the abundance of potassium, close redox potential to lithium, and similar electrochemistry with lithium system. Although carbon materials have been studied as KIB anodes, investigations on KIB cathodes have been scarcely reported. A comprehensive study on potassium Prussian blue K0.220Fe[Fe(CN)6]0.805⋅4.01H2O nanoparticles as a potential cathode material is for the first time reported. The cathode exhibits a high discharge voltage of 3.1–3.4 V, a high reversible capacity of 73.2 mAh g−1, and great cyclability at both low and high rates with a very small capacity decay rate of ≈0.09% per cycle. Electrochemical reaction mechanism analysis identifies the carbon‐coordinated FeIII/FeII couple as redox‐active site and proves structural stability of the cathode during charge/discharge. Furthermore, for the first time, a KIB full‐cell is presented by coupling the nanoparticles with commercial carbon materials. The full‐cell delivers a capacity of 68.5 mAh g−1 at 100 mA g−1 and retains 93.4% of the capacity after 50 cycles. Considering the low cost and material sustainability as well as the great electrochemical performances, this work may pave the way toward more studies on KIB cathodes and trigger future attention on rechargeable KIBs. Potassium Prussian blue nanoparticles are reported as a potential cathode material for potassium‐ion batteries. The cathode exhibits high reversible capacity, excellent cyclability, and great rate capability. Electrochemical mechanism analysis reveals the active‐redox site and proves the structural stability during charge/discharge. Pairing with commercially available carbon materials, a potassium‐ion battery full cell is demonstrated for the first time.