Electrochemical study on xLi2MnO3-(1-x)LiNi1/3Co1/3Mn1/3O2 (x=0.5) layered complex cathode showing voltage hysteresis

The layered complex cathode has attracted much interest recently due to its high capacity, which exceeds 250 mAhg−1. On the other hand, it also shows large voltage hysteresis which causes energy loss when applied as a practical battery material. It has been reported that the hysteresis is an intrinsic bulk property, and the phenomenological model due to the migration of transition metal has been also proposed. Then, it is considered that to study the hysteresis for various compositions of transition metal is valuable to clarify the phenomenon. In this work, the layered complex cathode of 0.5Li2MnO3-0.5LiNi1/3Co1/3Mn1/3O2 was investigated. The results are discussed in comparison with the previous reports for 0.5Li2MnO3-0.5LiMn0.5Ni0.5O2. Investigating dQ/dV profilesrevealed that redox peaks at around 3.75 V showed small dependency on composition of transition metal, while it seemed that a reduction peak at 3.26 V was independent on the composition. Precise measurement of open circuit potential vs. capacity characteristics demonstrated that the energy dissipation during a cycle was abut 26 kJmol−1.