Acta Phys. -Chim. Sin. ›› 2008, Vol. 24 ›› Issue (09): 1669-1674.doi: 10.3866/PKU.WHXB20080924

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Preparation and Electrochemical Performance of Na-Mn-O Cathode Materials

YANG Shun-Yi; WANG Xian-You; WEI Jian-Liang; LI Xiu-Qin; TANG An-Ping   

  1. School of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, P. R. China
  • Received:2008-01-14 Revised:2008-06-02 Published:2008-09-10
  • Contact: WANG Xian-You

Abstract: The precursor of sodium manganese oxide xerogel was prepared from Mn(CH3COO)2·4H2O and Na2CO3 solution by sol-gel method, then sodiummanganese oxide cathode materials were prepared through calcinating xerogel precursors in air atmosphere. The structure and performance of as-prepared cathode materials were characterized by Flourier-infrared spectra (FT-IR), thermogravimetric analysis (TG), X-ray diffractometer (XRD), scanning electron microscope (SEM), and galvanostatic charge/discharge. The results showed that layered sodium manganese oxide with a stable phase could be obtained at a temperature of about 600 ℃, and its crystal system was hexagonal P2 structure with space group P63/mmc. It had been found by PowderX calculation that the lattice parameters a was 0.284 nmand c was 1.116 nm. Since the radius of Na+ (0.095 nm) was bigger than Li+ (0.076 nm), limited removal of sodium ions fromthe layered host lattice could decrease the resistance of lithiuminsertion/deinsertion in MnO6 layers, and thus the electrochemical performance of the material could be apparently improved. The second discharge capacity of the material reached 176 mAh·g -1 at a rate of 25 mA·g -1 in the cutoff voltage range of 2.0-4.3 V, and the capacity retention was still 90.9%after 20 cycles.

Key words: Lithium-ion battery, Layered cathode material, Sodium manganese oxide, Sol-gel method