Carbon coated hollow Na₂FePO₄F spheres for Na-ion battery cathodes

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• 作者：Alex Langrock ; Yunhua Xu ; Yihang Liu ; Sheryl Ehrman ; Ayyakkannu Manivannan¹ ; Chunsheng Wang ; ^{cswang@umd.edu}
• 关键词：Ultrasonic spray pyrolysis ; Na-ion battery ; Carbon coated Na2FePO4F ; Porous hollow particles
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：1 February, 2013
• 年：2013
• 卷：223
• 期：Complete
• 页码：62-67
• 全文大小：884 K

文摘

Carbon coated porous hollow Na₂FePO₄F (C/Na₂FePO₄F) spheres with 500?nm diameter and 80?nm wall thickness are synthesized by a one-step template-free ultrasonic spray pyrolysis process using sucrose as the carbon source. Nano-sized porous hollow C/Na₂FePO₄F spheres allow electrolyte to penetrate into the hollow structure, and thus the electrochemical reaction can take place on both the outside and inside surface and in the pores. Also, the carbon coating on Na₂FePO₄F hollow spheres enhances the electronic conductivity and charge transfer reaction kinetics. The unique carbon coated porous hollow C/Na₂FePO₄F cathodes deliver 89?mAh?g^?1 capacity at a low rate of 0.1C, and 75?mAh?g^?1 at 1C, and maintains 33 % of capacity at 9C. After 750 cycles at 1C, C/Na₂FePO₄F cathodes can still provide 60?mAh?g^?1, which is 80 % of initial capacity. The significant advance in electrochemical performance of hollow C/Na₂FePO₄F spheres combined with mature aerosol spray synthesis technology make these carbon coated porous hollow C/Na₂FePO₄F spheres very promising as cathode materials for practical applications in Na-ion batteries.