Comparative study on experiments and simulation of blended cathode active materials for lithium ion batteries

We simulate the electrochemical properties of Li-ion cells consisting of a blended cathode composed of LiMn ₂ O ₄ and LiNi _0.6 Co _0.2 Mn _0.2 O ₂ and an artificial graphite anode using the Li-ion battery model available in COMSOL MULTIPHYSICS 4.4 along with a capacity fade model. The discharge profiles of the pure and blended cathodes at various current rates obtained through simulations and experimental results are well matched. By combining two capacity fade models available in literature, namely the solid electrolyte interphase (SEI) growth model and the Mn ²⁺ dissolution model, the cycling performance of the pure LiMn ₂ O ₄ cells at 25 °C are successfully simulated and found to be in a good agreement with the experimental results. The blended cathode exhibits better capacity retention than the pure LiMn ₂ O ₄ during cycling. We also observed that at high powers, the gravimetric energy density of the LiMn ₂ O ₄ cathode exceeds that of the LiNi _0.6 Co _0.2 Mn _0.2 O ₂ cathode; the reverse effect is seen at low powers. Further, we were able to easily modulate the energy and power densities of the blended cathode system by changing the blend ratio in our simulation model.