Synthesis and Characterization of Electrophoretically Deposited Nanostructured LiCoPO4 for Rechargeable Lithium Ion Batteries

Nanosized LiCoPO4 (LCP) was prepared using a simple sol-gel method. For the first time, electrophoretic deposition process was employed to fabricate a LiCoPO4 cathode material in order to improve the electrochemical performance. The prepared powder was deposited on titanium plate by electrophoretic deposition and their electrochemical properties were studied. The electrochemical properties were analyzed by using cyclic voltagramm studies, impedance studies, and charge/discharge tests. The thickness of the prepared cathode material was found to be 11-12？μm by using scanning electron microscope. The initial specific capacity and the charge transfer resistance (Rct) of the prepared cathode was 103？mAh/g and 851？？, respectively. The charge/discharge profiles showed moderate columbic efficiency of 70%. 1. Introduction Lithium-ion batteries exhibit good electrochemical performance compared to other types of batteries due to long storage life and environmentally friendly and low maintenance. They are the focus of attention as good energy storage devices and are nowadays commonly used in portable electronic devices such as laptops, mobile phones, camera, and so forth. For better performance, cathode materials with high specific energy density, high power density, and excellent thermal stability are necessary for lithium-ion batteries [1, 2]. LiCoO2 is the commonly used cathode material. It has both high voltage and capacity but has its own disadvantages like high cost, toxic properties, and safety issues [3, 4]. So a quest for other cathode materials arises. Cathode materials having the general formula LiMPO4 (M = Fe, Co, Mn, and Ni) are seeking attention nowadays [5–9]. They are having high theoretical capacity approximately 170？mAh/g. Their operating voltages are high. They are having a stable structure on charging and discharging, thermal stability, and flat voltage profile [10, 11]. Lithium cobalt phosphate (LiCoPO4) has high energy density (750？Wh) which is comparable to lithium cobalt oxide (LiCoO2) [12]. LiCoPO4 is one material which has high voltage and capacity compared to LiCoO2 and is predicted to have ~1.6 times the specific energy of LiCoO2 [13–16]. It can operate at high voltage typically 5？V. It is cost effective and one of the promising cathode material. But their main disadvantages are their poor electronic and ionic conductivity and poor rate cyclability [17, 18]. Even though the theoretical capacity of LiCoPO4 is 167？mAh/g, the obtained values are still lower due to the above reason. Reduction in particle size to nanometer size, doping with