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Journal of Power Sources 195 (2010 2877–2882 Contents lists available at ScienceDirect Journal of Power Sources j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j p o w s o u r Hydrothermal preparation of LiFePO 4nanocrystals mediated by organic acid Jiangfeng Ni a ,?,Masanori Morishita b ,Yoshiteru Kawabe b ,Masaharu Watada b ,Nobuhiko Takeichi a ,Tetsuo Sakai a ,? a National Institute of Advanced Industrial Science and Technology,Kansai Center,1-8-31Midorigaoka,Ikeda,Osaka 563-8577,Japan b GS Yuasa Corporation,Nishinosho,Kisshoin,Minami-ku,Kyoto 601-8520,Japan a r t i c l e i n f o Article history: Received 21July 2009 Received in revised form 2November 2009Accepted 2November 2009 Available online 10 November 2009Keywords: Lithium ion battery Cathode LiFePO 4 Hydrothermal Nanocrystal Synchrotron radiation a b s t r a c t Well-crystallized LiFePO 4nanoparticles have been directly synthesized in a short time via hydrothermal process in the presence of organic acid,e.g.citric acid or ascorbic acid.These acid-mediated LiFePO 4products exhibit a phase-pure and nanocrystal nature with size about 50–100nm.Two critical roles that the organic acid mediator plays in hydrothermal process are recognized and a rational mechanism is explored.After a post carbon-coating treatment at 600?C for 1h,these mediated LiFePO 4materials show a high electrochemical activity in terms of reversible capacity,cycling stability and rate capability.Partic-ularly,LiFePO 4mediated by ascorbic acid can deliver a capacity of 162mAh g ?1at 0.1C,154mAh g ?1at 1C,and 122mAh g ?1at 5C.The crystalline structure,particle morphology,and surface microstructure were characterized by high-energy synchrotron X-ray diffraction (XRD,transmission electron microscopy (TEMand scanning electron microscopy (SEM,and Raman spectroscopy,respectively.And the electro-chemical properties were thoroughly investigated by galvanostatic test and electrochemical impedance spectroscopy (EIS. ? 2009 Els