Enhancing the elevated temperature performance of high voltage LiNi0.5Mn1.5O4 by V doping with in-situ carbon and polyimide encapsulation

Abstract

We report the enhanced electrochemical performance of high voltage LiNi0.5Mn1.5O4 cathode by small amount of aliovalent doping in Li-site (Li0.995V0.005Ni0.5Mn1.5O4) and polyimide-carbon (PI-C) coating as well. Such small amount of V-doping in Li-sites leads to the crystallization of ordered spinel. The performances of the cathodes are studied in half-cell assembly at elevated temperature conditions (50, 55 and 60 degrees C). Although, the notable improvement in elevated temperature conditions are noted for Li0.995V0.005Ni0.5Mn1.5O4 phase at 50 degrees C, but not sustained while increasing to 55 and 60 degrees C. Nevertheless, the combined advantages of mixed conducting (ionic and electronic) features of PI-C, an excellent performance are noted for the Li0.995V0.005Ni0.5Mn1.5O4 phase after introducing the PI-C layer, irrespective of the testing temperature. Cyclic voltammetry and impedance studies are also performed to corroborate the Li-ion kinetics. (C) 2015 Elsevier B.V. All rights reserved.