Crystalline maricite NaFePO4 as a positive electrode material for sodium secondary batteries operating at intermediate temperature

JOURNAL OF POWER SOURCES

卷:377

Article

Hwang, Jinkwang¹  Matsumoto, Kazuhiko^1,4  Orikasa, Yuki²  Katayama, Misaki²  Inada, Yasuhiro²  Nohira, Toshiyuki^3,4  Hagiwara, Rika^1,4 

[1] Kyoto Univ, Grad Sch Energy Sci, Sakyo Ku, Kyoto 6068501, Japan

[2] Ritsumeikan Univ, Dept Appl Chem, 1-1-1 Noji Higashi, Kusatsu, Shiga 5258577, Japan

[3] Kyoto Univ, Inst Adv Energy, Uji, Kyoto 6110011, Japan

[4] Kyoto Univ, Unit Elements Strategy Initiat Catalysts & Batter, Kyoto 6158510, Japan

关键词: Sodium secondary batteries;    Olivine;    Maricite;    Ionic liquid;    Intermediate-temperature operation;   

DOI  :  10.1016/j.jpowsour.2017.12.003

来源: Elsevier

【 摘 要 】

Maricite NaFePO4 (m-NaFePO4) was investigated as a positive electrode material for intermediate-temperature operation of sodium secondary batteries using ionic liquid electrolytes. Powdered m-NaFePO4 was prepared by a conventional solid-state method at 873 K and subsequently fabricated in two different conditions; one is ball milled in acetone and the other is re-calcined at 873 K after the ball-milling. Electrochemical properties of the electrodes prepared with the as-synthesized m-NaFePO4, the ball-milled m-NaFePO4, and the re-calcined m-NaFePO4 were investigated in Na[FSA]-[C(2)C(1)im] [FSA] (C(2)C(1)im(+) = 1-ethyl-3-methylimidazolium, FSA(-) = bis (fluorosulfonyl)amide) ionic liquid electrolytes at 298 K and 363 K to assess the effects of temperature and particle size on their electrochemical properties. A reversible charge-discharge capacity of 107 mAh g(-1) was achieved with a coulombic efficiency > 98% from the 2nd cycle using the ball-milled m-NaFePO4 electrode at a C-rate of 0.1 C and 363 K. Electrochemical impedance spectroscopy using m-NaFePO4/m-NaFePO4 symmetric cells indicated that inactive m-NaFePO4 becomes an active material through ball-milling treatment and elevation of operating temperature. X-ray diffraction analysis of crystalline m-NaFePO4 confirmed the lattice contraction and expansion upon charging and discharging, respectively. These results indicate that the desodiation-sodiation process in m-NaFePO4 is reversible in the intermediate-temperature range.

【 授权许可】

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