Investigation of Olivine Phosphate Nanomaterials For Electric Vehicle Type Lithium Ion Batteries

One of the most crucial challenges for the development of high performance lithium ion batteries for future vehicle is the development of high power durable cathode material. The cathode materials must be robust and stable upon repeated charging and discharging. Furthermore, the allowable charge-discharge rate should also be high, say 10C or above. There should also be no compromise in safety issues. Hence, electronconductivity and ion conductivity are crucial properties affecting the performance.The aim of this project is to develop high energy storage, as well as high power and high charging rate, lithium ion batteries (LIB) for hybrid electric vehicles (HEV) and/or EV based on olivine lithium transition metal phosphate (LiMPO4) nanomaterials. The proposal consists of three parts: (1) controllable synthesis of large-scale olivine-typeLiFePO4 and LiMnPO4, and their solid solution LiFe(1-x)Mn(x)PO4 nanocrystallites (<100nm) with ultrathin plate-like morphology and narrow particle size distribution; (2) characterization of the crystal structure, morphology, composition, electronic and ionic conductivity, and electrochemical characteristics of the LiMPO4 nanocrystallites synthesized; (3) design, fabricate, and optimize of LIB based on LiMPO4nanocrystallites.We will attempt to synthesize ultrafine LiMPO4 nanocrystallites with well-defined plate-like geometry by three simple and inexpensive methods: (i) hydrothermal method; (ii) precipitation in combination with high-energy ball milling and (iii) moderate temperature calcinations, hydrothermal plus ion-exchange. The structure, composition, morphology and particle size of LiMPO4 nanocrystallites will be characterized systematically to provide information for optimizing the processing parameters of cathode powder synthesis. The LiMPO4 nanocrystallites will be used to fabricate LIB. Two types of batteries will be fabricated and characterized: (1) prototype half-cell using LiMPO4 nanocrystallites as cathode and lithium metal as anode, (2) industrial type cell employing LiMPO4 nanocrystallites as cathode and graphite as anode. Properties related to LIB cell performances, such as charge-discharge cycling hehaviour, will be carefully studied to provide detail information for achieving high energy storage capacity, high output power and high charging rate LIB suitable for HEV or EV.