Lithium-ion conductors of the system LiCo_(1-x)Fe_xO_2: afirst electrochemical investigation

摘要

LiCo_(1-x)FexO_2 compounds (0<= x<= 1) with ordered rock salt structure of cx-NaFeO_2 type were prepared by ion exchange reaction in a molten eutectic mixture from the corresponding Na compounds. The Li compounds are investigated by galvanostatic and potentiostatic cycling experiments. The new form, ion-exchanged LiCoO_2 (IE-Li- CoO_2), is compared in its electrochemical behaviour with the known high temperature HT -LiCoO_2. A different behaviour at cycling up to 4.8 V versus Li/Li + is evidenced. Galvanostatic and potentiostatic cycling experiments were also carried out on the iron-containing compounds. Charge voltage increases and electrochemical capacity decreases with increasing iron content and reaches a low value for LiFeO2 with an iron content of x = 0.6. Reasons that may account for this behaviour are discussed.