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

Nowadays the request of better performing batteries is constantly increasing. For this reason, combining high voltage cathode, i.e. LMNO (Lithium Manganese Nickel Oxide), together with high capacity anodes, i.e silicon, can be an interesting solution. To improve the specific energy, one solution is to increase the cell voltage and the capacity. 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 LNMO (Lithium Nickel Manganese Oxide) and LFP (Lithium Iron Phosphate) in order to combine their inherent positive characteristic to get better performing electrodes. The pristine materials LNMO and LFP were furnished by Johnson Matthey, while the graphite by Elkem, both partners of the Hydra project. The materials were mixed using two different approaches, ball milling and resonant acoustic mixing (RAM). The blended materials were characterized by XRD, FESEM and electrochemically tested both in half and full cell. Results The results obtained are showing that a homogeneous coating of LFP is actually hard to obtain through the ball milling approach, however the electrochemical data confirm that both materials actively contribute to the capacity of the blended electrodes. The materials mixed with RAM exhibit better dispersion of LFP particles, especially with low content of LFP (below 10%wt) and good electrochemical performances, especially in the full cell configuration. The optimization work carried out on different ball milling parameters (frequency, time) and weight composition of the mixed material showed that mild ball billing treatment and low quantity of LFP are the conditions required to get the best blended electrodes with this approach. The RAM approach is able to better distribute the LFP particles, but also in this case low amount of LFP gives the best results. The better electrochemical performances of the blended electrodes could be ascribed to the beneficial effect of the LFP, which is able to partially mitigate the dissolution of transition metals from the LNMO into the electrolyte.