Enhanced capacity and lower mean charge voltage of Li-rich cathodes for lithium ion batteries resulting from low-temperature electrochemical activation

Abstract

High capacity and high energy cathodes prepared from Li-rich 0.35Li₂MnO₃·0.65Li[Mn_0.45Ni_0.35Co_0.20]O₂ materials must be activated in Li-ion cells prior to normal cycling, in order to achieve their high discharge capacity of >250 mA h g⁻¹. Activation is performed by charging the electrodes to potentials of 4.7–4.8 V vs. Li/Li⁺. This communication reports on the discovery that electrochemical activation of these cathode materials at low temperatures (0–15 °C) increases their discharge capacity, lowers average charge voltage, and diminishes voltage hysteresis. Work with the above mentioned material is reported as a representative example.