Energy storage technology is key for the realization of renewable energy sources and phasing out of fossil fuels. There are still some challenges to overcome in order to realize the large scale production and usage of energy storage worldwide, including rapid charging limitations, early cell aging, energy density restrictions and recycling of used batteries. In order to continue to improve the performance of battery storage systems, the materials, production techniques, cell manufacture and cycling strategies all need to be studied in order to gain more information on how to improve them. Identifying limiting performance factors and creating strategies to improve them require knowledge about the materials and cell systems themselves. In this study, a cobalt free active material, Lithium Nickel Manganese Oxide, LiNi_0.5Mn_1.5O₄ (LNMO), was employed in the production of cathodes for high voltage lithium ion battery (LIB) applications. LNMO is an attractive cathode active material due to its high operating potential (~4.7 vs. Li/Li⁺ [1]), non-toxicity and low cost. The practical application of LNMO cathodes in LIBs has been relatively limited, especially for large scale application, due challenges associated with the material (eg. electrolyte decomposition at high voltage, self-discharge and dissolution of the transition metals [2]).

In this study the impact of the production parameters, namely the dispersion composition and calendaring densities, on the performance of the LNMO cathodes was investigated. Both the material properties of the electrode (porosity, adhesion etc.) was investigated, as well as the electrochemical properties (through cyclic voltammetry, impedance spectroscopy and galvanostatic measurements). The long term cycling capability, as well as the rate capability of the cathode was investigated when prepared with different conductive additive ratios (1.5, 3.0 and 5 wt. %) and calendering strengths (2.0, 2.2, 2.4 and > 3.0 g/cm³). A non-linear relationship between the density after calendaring and the rate capability was observed for electrodes with conductive additive ratios above 1.5 wt %. The lithium diffusivity was also impacted by both the conductive additive ratios and calendaring densities, which could be related to the particle size distribution and porosity of the cathode coatings. The capacity loss when the cycling rate was increased also corresponded to the cathode porosities.

References:

[1] G. Gabrielli, M. Marinaro, M. Mancini, P. Axmann and M. Wohlfahrt-Mehrens, J. Power Sources 351 (2017) 35-44.

[2] R. Amin, N. Muralidharan, R. K. Petla, H. Ben Yahia, S. A. Jassim Al-Hail, R. Essehli, C. Daniel, M. A. Khaleel, I. Belharouak, J. Power Sources, 467 (2020) 228318.