物理化学学报 >> 2008, Vol. 24 >> Issue (09): 1669-1674.doi: 10.3866/PKU.WHXB20080924

研究论文 上一篇    下一篇

Na-Mn-O正极材料的合成及电化学性能

杨顺毅; 王先友; 魏建良; 李秀琴; 唐安平   

  1. 湘潭大学化学学院, 湖南 湘潭 411105
  • 收稿日期:2008-01-14 修回日期:2008-06-02 发布日期:2008-09-10
  • 通讯作者: 王先友 E-mail:wxianyou@yahoo.com

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 E-mail:wxianyou@yahoo.com

摘要: 以Mn(CH3COO)2·4H2O为锰源, 以Na2CO3为钠源, 通过溶液-凝胶法合成干凝胶前驱体, 将前驱体在空气气氛中焙烧得到Na-Mn-O正极材料. 并用傅立叶红外光谱(FT-IR), 热重分析(TG), X射线衍射(XRD), 扫描电镜(SEM), 恒流充放电测试等对材料结构和性能进行研究. 结果表明,600 ℃焙烧的样品为结构稳定的层状锰酸钠, 属于六方层状P2结构, 空间群为P63/mmc, 通过PowderX软件计算得到其晶胞参数为a=0.284 nm, c=1.116 nm. Na-Mn-O正极材料在Li+嵌入和脱出过程中, 部分Na+从层状主晶格中脱出, 使得Li+在MnO6层间的嵌/脱阻力减小(由于Na+(0.095 nm)半径比Li+(0.076 nm)大), 电化学性能明显改善. 在充放电电流密度为25 mA·g-1, 电压在2.0-4.3 V范围时, 600 ℃焙烧的样品第二次放电容量高达176 mAh·g-1, 20次循环后, 容量保持率仍有90.9%.

关键词: 锂离子电池, 层状正极材料, 钠锰氧化物, 溶液-凝胶法

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

MSC2000: 

  • O646