Electrochemical Properties of Cu Doped Lithium Manganese Silicate/PANI Composite As Cathode Material for Lithium-Ion Batteries

Abstract

Development of cathode materials for lithium battery application like electric vehicle (EV) and plug-in hybrid electric vehicle (PHEV) requires high capacity materials[1]. At the same time, cost, environmental concerns and safety issues cannot be excluded. Recently, lithium transition-metal silicates such as Li2MSiO4 (M=Fe, Mn and Co) have been extensively studied as cathode materials for lithium ion batteries, due to high theoretical capacity and better thermal stability than lithium transition metal oxides such as LiCoO2. Among them, Li2MnSiO4 cathode could be a better choice as a high capacity( ~330 mAh/g) cathode for lithium ion batteries than Li2FeSiO4 cathode material. Due to Mn2+/Mn3+ and Mn3+/Mn4+ redox couples, extraction of two lithium ions can be achieved from Li2MnSiO4. However, due to defects such as structure change after the first charge and low electronic conductivity(~ < 10-14S/cm), this material has poor cycle performance and lower capacity than the theoretical prediction [2-3]. In this regard, the current work is aimed on the improvement of capacity and cycle stability of Li2MnSiO4 cathode active material by applying Cu doping and poly-aniline composites. The Li2Mn0.95Cu0.05SiO4were prepared using the sol-gel synthesis. PANI was synthesized by oxidative polymerization. XRD patterns as shown in Figure 1 exhibit that the Cu doping and PANI composite does not contribute to structure change of Li2MnSiO4. From the cycle performances as shown in Figure 2, the Li2Mn0.95Cu0.05SiO4/PANI cell shows a high discharge capacity, as well as improved cycle retention compared with pristine Li2MnSiO4 material. Synthesis methodology of Li2Mn0.95Cu0.05SiO4/PANI materials along with their physical, morphological and electrochemical characteristics will be discussed in detail. References : [1] R.J. Gummow, N.Sharma, V.K.Peterson, Y.He, J. solid state chem., 188 (2012) 32–37. [2] R. Dominko, M. Bele, A. Kokalj, M. Gaberscek, J. Jamnik , J. Power Sources., 174 (2007) 457–461. [3] D. M. Kempaiah, D. Rangappa, I. Honma, Chem. Commun.,48 (2012) 2698–2700.