Towards understanding the functional mechanism and synergistic effects of LiMn2O4 - LiNi0.5Mn0.3Co0.2O2 blended positive electrodes for Lithium-ion batteries

Blended positive electrodes consisting of mixtures of LiMn2O4 spinel (LMO)and layered LiNi0.5Mn0.4Co0.2O2 (NMC) have been studied by coupling electrochemicaltesting to operando synchrotron based X-ray absorption andpowder diffraction experiments to shed light on their redox mechanism. BlendingNMC with LMO results in enhanced energy density at high rates, with thecomposition with 25% LMO exhibiting the best electrochemical performance.Tests with a special electrochemical setup detecting the contribution of eachblend component indicate that the effective current load on each blend componentcan be significantly different from the nominal rate and also varies asfunction of SoC. Operando studies enabled to monitor the evolution of oxidationstate and changes in the crystal structure, which are in agreement withthe expected behavior of the individual components considering the materialspecific electrochemical current loads. These findings should contribute to a deeper mechanistic understanding of blended electrodes to foster a rationaldriven approach for their design.