Morphological effect on high compaction density nickel-rich layered oxide cathodes during electrochemical lithiation and delithiation

The morphological effect of the blended single-crystalline Li[Ni_0.8Co_0.1Mn_0.1]O₂(NCM-C) and spherical secondary polycrystalline Li[Ni_0.8Co_0.1Mn_0.1]O₂(NCM-SP) cathodes (3:7 in weight) were systematically investigated. Calendering properties of the NCM-C, NCM-SP, and blended cathode were tested on a pilot-scale compactor. The values of maximal coating density and compaction resistance fitted by Heckel's equation indicate that the addition of moderate amounts of NCM-C into NCM-SP produced a significant improvement in the compaction degree and electrical conductivity of cathode laminate. The addition of NCM-C is also found to help reduce the generated electrode stress during electrochemical lithiation and delithiation which is confirmed by using the multi-beam optical sensor (MOS) technique. In the pouch-type full cell test utilizing artificial graphite as the negative electrode, the retained capacity is about 85.3% of its initial capacity by applying 1.0 C current at 25 °C after 700 cycles. The rate capability is also improved in the blended cathode even at a 2.0 C discharge rate, keeping 97.3% of its initial specific capacity (0.33C rate). It is suggested that the mixed electrode is considered to be a quite promising cathode electrode material to be applied for lithium-ion batteries.