LiMnTiO4 with the Na0.44MnO2 structure as a positive electrode for lithium-ion batteries

A.M. Amigues, H.F.J. Glass and S.E. Dutton
University of Cambridge,
United Kingdom

Keywords: Lithium battery cathode

Summary:

Achieving more efficient cathode materials is key to the development of lithium-ion batteries. The objective of this work is to investigate the electrochemical performance of a new polymorph of LiMnTiO4 with the Na0.44MnO2 structure synthesized via ion-exchange from its sodium analogue, NaMnTiO4. LiMnTiO4 was cycled vs Li at room temperature and up to 0.89 lithium ions can be reversibly inserted into the structure, with a discharge capacity of 137 mAh/g after 20 cycles at C/20. When cycled at 60°C at a C/20 rate, LiMnTiO4 has a first charge capacity of 151 mAh/g. Assuming that no other processes contribute to the overall capacity, this corresponds to the formation of Li0.02MnTiO4 and represents 98% of the theoretical capacity. The first discharge reaches a capacity of 230 mAh/g, corresponding to the formation of Li1.51MnTiO4. Subsequent charges/discharges have a reversible capacity of ∼164 mAh/g, corresponding to the removal/insertion of 1.06 Li-ions. This confirms that kinetics and cell configuration limit the performance at room temperature and that further optimizations of the electrode material could improve it.