Part I: Electronic and ionic transport properties of the ordered and disordered LiNi0.5Mn1.5O4 spinel cathode

Here, we report on the electronic and ionic conductivity and diffusivity of the ordered (P4(3)32) and disordered (Fd (3) over barm) LiNi0.5Mn1.5O4 spinel material, which have been determined by using ion and electron blocking cell configurations as a function of lithium concentration and temperature. The disordered phase exhibits about fifteen-time higher electronic conductivity than the ordered phase at room temperature in the lithiated state. Upon delithiation, the electronic conductivity of the ordered LiNi0.5Mn1.5O4 phase increases and reaches the same levels observed for the disordered phase. The ionic conductivity and diffusivity of LiNi0.5Mn1.5O4, in the ordered and disordered forms, are in the range of -1 x 10(-9) S/cm and -5 x 10(-9) cm2/s, respectively. Both phases exhibit similar activation energies for the ionic conductivity and diffusivity, i.e. 0.70 +/- 0.2eV and 0.74 +/- 0.2eV, respectively. It can be concluded from the obtained results that the electrochemical performance of LiNi0.5Mn1.5O4, whether ordered or disordered, is limited by lithium transport, but is fast enough to allow charge/discharge of micron-scale particles at practical C-rates. (C) 2017 Elsevier B.V. All rights reserved.