Li(Ni1/3Co1/3Mn1/3)O2 as a suitable cathode for high power applications

The electrochemical performance of the layered Li(Ni1/3Co1/3Mn1/3)O2 material have been investigated as a promising cathode for a hybrid electric vehicle (HEV) application. A C/Li(Ni1/3Co1/3Mn1/3)O2 cell, cycled between 2.9 and 4.1 V at 1.5 C rate, does not show any sign of capacity fade up to 100 cycles, whereas at the 5 C rate, a loss of only 18% of capacity is observed after 200 cycles. The Li(Ni1/3Co1/3Mn1/3)O2 host cathode converts from the hexagonal to a monoclinic symmetry at a high state of charge. The cell pulse power capability on charge and discharge were found to exceed the requirement for powering a hybrid HEV. The accelerated calendar life tests performed on C/Li(Ni1/3Co1/3Mn1/3)O2 cells charged at 4.1 V and stored at 50 °C have shown a limited area specific impedance (ASI) increase unlike C/Li(Ni0.8Co0.2)O2 based-cells. A differential scanning calorimetry (DSC) comparative study clearly showed that the thermal stability of Li(Ni1/3Co1/3Mn1/3)O2 is much better than that of Li(Ni0.8Co0.2)O2 and Li(Ni0.8Co0.15Al0.05)O2 cathodes. Also, DSC data of Li(Ni1/3Co1/3Mn1/3)O2 cathode charged at 4.1, 4.3, and 4.6 V are presented and their corresponding exothermic heat flow peaks are discussed.