In order to increase the energy density of lithium-ion batteries, there are two levels; one is the increase of the specific capacity of both positive and negative active materials (i. e. in Li/S8 technology) and/or the increase of the battery voltage. The most simple solution a promising solution is theo use of positive active materials with high potential (up to 5V vs Li + / Li) [1] because it does not change the technology conception. Among the different materials, The spinel LiNi_1/2Mn_3/2O₄ has a theoretical capacity of 147 mAh/g and a potential of 4.8 V vs Li⁺/Li, which enable a high energy density [2] (at least 20% more than standard LiCoO2). In the literature, a wide range of values for diffusion coefficient have been reported and only few studies reports values for exchange current density [3,4,5] . This work intended to highlight the impact of thermodynamic factor on the diffusion and to bring new values for the exchange current density, measured by impedance spectroscopy. The study of thin film of spinel LiNi_1/2Mn_3/2O₄ enables to use simplified equations for extracting kinetics and thermodynamics values like exchange current density at the interface of the material, values of the diffusion in the thin electrode and thermodynamic factor that affect the mobility in the structure, depending on the state of charge. These results have then been compared to the ones obtained on composite electrodes. Very and good agreement were obtained even using a 1D model on composite electrodes.

[1] Tarascon et al. Nature Mater. 2011
[2] Yi et al. J. Power Sources, 2016
[3] Aurbach et al. Electrochim. Acta, 2005
[4] Amin et al. J. Power Sources, 2017
[5] Nishikawa et al. J. Electroanal. Chem. 2017