Innovative hybrid high voltage electrodes based on LMNO/LFP materials for lithium ion batteries

Nowadays the markets of electric vehicles (EV) and energy storage devices are fast increasing pushing a constant increase in the demand for greener and more sustainable power sources. In particular, for EVs applications, batteries guaranteeing long cycle life combined with high specific energy and high power density are needed. To increase the specific energy, one solution is to increase the cell voltage and the capacity. For this reason, combine high voltage cathode, i.e. LMNO (Lithium Manganese Nickel Oxide), together with high capacity anodes, i.e silicon, can be an interesting solution. Unfortunately, LNMO suffers easy cation leaching during cycling, in particular at high Crate. The present abstract shows results achieved within HYDRA H2020 project based on the synthesis of new blended materials combining LMNO and LFP (Lithium Iron Phosphate) in order to combine their inherent positive characteristic to get better performing electrodes. LFP was chosen because of its outstanding thermal and electrochemical stability, as well as its Li-redox activity at a relatively high voltage. Therefore, the presence of the LFP should increase the performances of the LMNO, especially at higher current rates. In order to get a homogeneous coating of LFP particles on the LMNO surface, we used ball billing treatments modifying all parameters, such as frequency, time, and weight percent of LFP. The blended active materials were thus characterized from a morphological and structural point of view with FESEM and XRD analysis, and electrochemical characterization: galvanostatic cycling and cyclic voltammetry studies. The results obtained are showing that the mixing through ball milling does not significantly damage the structure of the two pristine materials but a homogeneous coating of LFP is actually hard to obtain through this method, However, the electrochemical data confirm that both materials actively contribute to the capacity of the blended electrodes. Fast microwave synthesis of LFP, to trigger his growth on LMNO particles, was followed as an alternative approach to obtain the desired hybrid material. The characterization of these materials showed that this procedure could provide a more consistent layer of LFP around the LMNO particles.