Preparation of the electrochemically formed spinel-lithium manganese oxides
Preparation of the electrochemically formed spinel-lithium manganese oxides
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DOI：
10.1016/j.jpowsour.2008.09.042
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发表时间：
2009-04
影响因子：
9.2
通讯作者：
K. Katakura;Kohei Wada;Yoshiyuki Kajiki;A. Yamamoto;Z. Ogumi
中科院分区：
文献类型：
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作者：
K. Katakura;Kohei Wada;Yoshiyuki Kajiki;A. Yamamoto;Z. Ogumi
以不同浓度的硝酸锰溶液为原料，采用阴极电化学沉淀法制备了尖晶石锂锰氧化物。从稀释的和浓缩的硝酸锰水溶液中生成了两种类型的氢氧化锰。在较低浓度(2mmoldmμ_3~2moldm−_3Mn(NO_3)_2AQ)中电化学沉淀后，在铂衬底上得到直径为0.2~5μm的均匀的圆盘状Mn(OH)_2晶体，而浓集的Mn(NO_3)_2AQ则形成长20~80μm，宽1~5 moldm的草叶状沉淀。在没有任何添加剂的情况下，两种氢氧化锰在750°C下焙烧含锂沉淀物后，将电化学形成的尖晶石LiMn2O4沉积在铂片上，准备进行电化学测量。电化学法合成的尖晶石LiMn2O4的二次粒子骨架(聚集体)的形状和大小可以通过电解条件来控制，除了用浓硝酸锰得到直径200 nm的纤维状纳米尖晶石LiMn2O4外，其他情况下都可以得到直径为200 nm的纳米结构的初晶。尽管这两种类型的尖晶石LiMn2O4即使在较高的扫描速度下也显示出形状良好的CV，但它将适合于高功率密度电池应用。这些行为被认为归因于处理后的尖晶石LiMn2O4的晶体尺寸和形状。
Electrochemically formed spinel-lithium manganese oxides were synthesized from manganese hydroxides prepared by a cathodic electrochemical precipitation from various concentrations of manganese nitrate solutions. Two types of manganese hydroxides were formed from diluted and concentrated Mn(NO3)2aqueous solutions. Uniform and equi-sized disk shaped Mn(OH)2crystals of 0.2–5μm in diameter were obtained on a Pt substrate after the electrochemical precipitation from lower concentration of ranging from 2mmoldm−3to 2moldm−3Mn(NO3)2aq., while the grass blade-like precipitate which is ascribed to manganese hydroxide with 20–80μm long and 1–5μm wide were formed from concentrated Mn(NO3)2aq. Both manganese hydroxides gave the electrochemically formed spinel-LiMn2O4onto a Pt sheet, which is ready for electrochemical measurement, after calcination of the Li incorporated precipitate at 750°C without any additives. While the shape and size of the secondary particle frameworks (aggregates) of the electrochemically formed spinel-LiMn2O4can be controlled by the electrolysis conditions, the nanostructured primary crystals of 200nm in diameter were obtained in all cases except that the fiber-like nanostructured spinel-LiMn2O4crystals with 200nm in diameter were obtained from concentrated Mn(NO3)2aq. Though these two types of electrochemically formed spinel-LiMn2O4showed well-shaped CVs even in higher scan rates, it would be suitable for high power density battery applications. These behaviors are assumed to be ascribed to the crystal size and shape of the processed spinel-LiMn2O4.