Lithium ion batteries are widely used in many applications and are the most promising energy storage systems for future mobility. Nevertheless, they still require further improvements in order to meet the energy and cost requirements for the next generation of electric vehicles. The development of cobalt free cathode materials with high capacity and high voltage can contribute significantly to further cost reduction of lithium ion batteries.

We present a series of Co-free, Li-rich Li_1+xNi_0.5Mn_1.5O₄ (0<x<1) compounds obtained via a low-temperature synthesis method. Chemically lithiated Li_1+yMn_1.5Ni_0.5O₄ (LMNS) (0< y < 1) with spherical particle morphology and high with tap densities (2.2 – 2.5 g/cm³) have been synthesized from coprecipitated mixed nickel manganese hydroxides as precursors. Figure 1 shows the charge/discharge curve of a sample with the composition Li_1.8Ni_0.5Mn_1.5O₄. The electrochemical mechanism in the low-potential region and the involved phase transitions, studied by different techniques including HR-TEM and XRD, will be discussed in more detail together with the electrochemical behavior under different operative conditions.

The obtained lithium‐nickel‐manganese oxide samples have been tailored with respect to composition and crystal structure in order to reach high capacities (up to 250 mAh g^-1) with good cycling stability. In addition, full cell data with Li_1+xNi_0.5Mn_1.5O_4.0 (0<x<1) compounds as cathode materials and either graphite or silicon/carbon composites as anodes will be presented. LiNi_0.5Mn_1.5O₄/Li_1.3Ni_0.5Mn_1.5O₄ blend cathodes with adapted extra lithium can be used to compensate irreversible capacity losses of silicon based anodes in full cells [1]. The cycle life of full cells can be further improved by optimizing morphology, particle size distribution and additional surface coating. The influence of electrode preparation and selection of electrolyte additives on long life stability will also be discussed.

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