Increasing Stack Energy Density Without Lifetime Penalty by Increasing Electrode Loading in Single Crystal Li[Ni 0.5 Mn 0.3 Co 0.2 ]O 2 /Graphite Pouch Cells

Abstract

Li-ion cell energy density can be improved by increasing the thickness of both the positive and negative electrode coatings, thus minimizing the fractional volume and mass from inactive cell materials. This study compares Li[Ni0.5Mn0.3Co0.2]O2 (NMC532)/graphite pouch cells with regular positive electrode loading (19.3 mg cm−2) and high positive electrode loading (29.2 mg cm−2) where both cell types have appropriate negative electrode loading. The results indicate similar capacity retention and impedance growth in long term cycling (when Li-plating is avoided) as well as similar rates of parasitic reactions at various upper cutoff potentials. Increasing the positive and negative loadings by 50%, as demonstrated here, can lead to an 8%–10% increase in volumetric energy density without a lifetime penalty.