In-Situ Synthesis of New Electrode Materials for Li-Ions Batteries using a cold FEG Environmental HRTEM

Conventional synthesis of new electrode materials, involving heat treatment in high-temperature furnaces, followed by materials characterization, is an extremely long process that can easily miss the best set of conditions for the synthesis of particular compounds. Consequently, it is important to develop in-situ techniques to directly observe changes in material structures and chemistry at the nanometer level during synthesis. We have previously demonstrated that for some structural features in carbon coated LiFePO4, observations in vacuum are not representative of the reality and in order to be useful, these real time observations need to be performed under representative atmospheres, such as air, oxygen or nitrogen [1]. Figure-1 presents HAADF images and EDS Ni and Mn combined maps of some Li, Ni, Mn and O compounds during in-situ thermal annealing up to 900 °C in vacuum. Contrary to the formation of LiNi0.5Mn1.5O4 crystals that is normally the result of ex-situ furnace annealing in air, Ni and Mn were found here to phase separate.