Mesoporous Cobalt Oxalate Nanostructures as High-Performance Anode Materials for Lithium-Ion Batteries: Ex Situ Electrochemical Mechanistic Study

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• 作者：Wei An Ang ; Yan Ling Cheah ; Chui Ling Wong ; Raghavan Prasanth ; Huey Hoon Hng ; Srinivasan Madhavi
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：August 15, 2013
• 年：2013
• 卷：117
• 期：32
• 页码：16316-16325
• 全文大小：583K
• 年卷期：v.117,no.32(August 15, 2013)
• ISSN：1932-7455

文摘

Two distinct mesoporous nanostructures, that is, rod and sheet cobalt oxalate (CoCb>2b>Ob>4b>), have been synthesized via facile chimie douce precipitation technique. The selective interaction between solvent type and crystallographic planes of the metal ion is the key factor in morphological variations. The morphology and microstructure are studied by high-resolution transmission electron microscopy. Structural characterization of the materials has been carried out by X-ray diffraction and confirmed phase pure CoCb>2b>Ob>4b>路2Hb>2b>O formation. The critical dehydration process of CoCb>2b>Ob>4b>路2Hb>2b>O led to anhydrous CoCb>2b>Ob>4b>, and its thermal properties are investigated by thermogravimetric analysis. Electrochemical properties of anhydrous CoCb>2b>Ob>4b> in half-cells are studied by cyclic voltammetry, galvanostatic charge鈥揹ischarge cycling, and electrochemical impedance spectroscopy. The studies showed that initial discharge capacity of anhydrous CoCb>2b>Ob>4b> nanorods and sheets is 1599 and 1518 mA h g^鈥?, respectively, at 1C-rate. Anhydrous CoCb>2b>Ob>4b> nanostructures fabricated by this chimie douce process achieved higher reversible capacity, more stable cycling, and better rate capabilities than reported. The electrochemical performances of anhydrous CoCb>2b>Ob>4b> nanostructures are found to be significantly influenced by morphology and porosity. In addition, the interfacial electrochemical mechanism related to the transitional metal oxidation states, phase structural changes, and distribution during cycling are validated.