Development of new high-energy anode material for large-scale secondary battery using metallic nano-particle

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The explosive demand for portable electronic devices has brought about an increase in the importance of compact, lightweight and reliable power sources. One of the most probable candidates for such requirements is lithium rechargeable battery. One is a lithiated transition metal oxide as cathode and the other graphite anode. However, it is well known that the quantity of active material per unit weight or volume determines the energy density of the battery. The graphite anode material commonly used in lithium rechargeable batteries suffers from small capacity per unit weight about 350mAh/g and/or per unit volume due to its low density. To overcome these disadvantages, considerable amounts of attempts have been made by several workers to find out alternative anode materials in place of graphite anodes. In this report, crystalline MnVィイD22ィエD2OィイD26ィエD2 and MnMoOィイD24ィエD2 was synthesized by a polymer gellation and solidstate reaction method and investigated for its physical and electrochemical properties as an anode material for lithium secondary battery. The physical properties of characterization was carried out by thermal analysis (TG/DTA), FT-IR, and SEM. Structural analysis by powder XRD, and spectroscopic analysis by XANES shows that the synthesized compound is MnVィイD22ィエD2OィイD26ィエD2 with brannerite structure. The Li insertion of MnVィイD22ィエD2OィイD26ィエD2 anode during the first charge showed a large capacity of about 1400 mAh/g, accompanied by irreversible structural transformation into amorphous material. Despite its structural transformation to amorphous during the first lithiation, subsequent cycles showed a capacity of about 800mAh/g. This report presents the advantage of this material over existing anode material and discusses the mechanism underlying the electrode process.