%0 Journal Article
%T Synthesis and Electrochemical Performance of LiMnPO4 by Hydrothermal Method
%A Daichi Fujimoto
%A Yu Lei
%A Zheng-Hong Huang
%A Feiyu Kang
%A Junichi Kawamura
%J International Journal of Electrochemistry
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/768912
%X LiMnPO4 with olivinestructure which is the promising candidate for high voltage cathode material was synthesized by hydrothermal method. In order to synthesize high purity and well-defined LiMnPO4, several precursors for Li, Mn, and P sources and hydrothermal reaction parameters including temperature and [H2O]/[Mn] value are optimized. By analyzing the structure, Mn valence, morphology, and chemical ratio via XRD, XPS, Raman, SEM, and ICP LiMnPO4 synthesized from manganese acetate tetrahydrate have single phase of LiMnPO4 without impurity and showed charge and discharge reaction caused by Mn2+/Mn3+ redox. Specific capacity of synthesized LiMnPO4 grew up during cycling. Moreover, when hydrothermal temperature was set at 150¡ãC and [H2O]/[Mn] value was set at 15, discharge capacity as high as 70£¿mAh/g was obtained at rate. 1. Introduction Lithium-ion batteries are used widely as mobile devices like cellphone and notebook. Recently, researchers are actively devoted into the lithium-ion battery research for high energy conversion system, such as electric vehicle. Most of present lithium-ion batteries have used LiCoO2 as cathode which was discovered in 1980 [1]. However, LiCoO2 which includes rare-metal Co has irreversible structure shift at discharging over 0.6 Li from LiCoO2 that cause discharge capacity limited to 120~130£¿mAh/g instead of theoretical capacity of 270£¿mAh/g [2]. Several alternative materials are proposed as cathode materials. In 1997, Padhi et al. reported that phospho-olivine can work as promising cathode materials for lithium-ion battery [3, 4]. Among phospho-olivine LiFePO4, LiMnPO4, LiCoPO4, and LiNiPO4 are considered to be possible candidates for lithium-ion battery. Compared to LiFePO4 and LiCoPO4, LiMnPO4 is a cathode material with high redox potential which can be used with presently available liquid electrolyte so that LiMnPO4 exceeds the energy density of LiFePO4 which is the most investigated electrode among LiMPO4 family [5]. The characteristic of this olivine structure is an inductive effect which appears due to a strong covalent bond of to rise up redox potential [3]. However, the strong covalent bond causes poor conductivity, decelerating the charge and discharge processes. So far, several approaches have been used to solve this problem, such as controlling the particle size, morphology, and carbon coating [6]. Solid state reaction is generally used to prepare LiMnPO4 [7, 8]. Besides this, other approaches such as sol-gel method [9, 10], precipitation [11¨C13], hydrothermal [10, 14¨C19], solvothermal method [14, 20¨C22], spray
%U http://www.hindawi.com/journals/ijelc/2014/768912/