Reactivity of lithium battery electrode materials toward non-aqueous electrolytes: spontaneous reactions at the electrode-electrolyte interface investigated by FTIR

Spontaneous reactions occurring at the surface of LiNi0.8Co0.2O2 and LiMn2O 4-based electrodes during the storage in organic nonaqueous electrolytes ha ve been investigated by diffuse reflectance FTIR technique. It is found tha t both materials spontaneously form different inorganic and organic compoun ds on their surface when in contact with electrolyte solutions. The nature of these self-acting reactions is moreover found to be similar to that of t he processes occurring during electrochemical cycling of the electrodes. Re action mechanisms and the final products depend on both electrode surface c hemistry and the nature of electrolyte used. It appears that the spontaneou s reactions are initiated by lithium deintercalation from the electrode act ive material. The influence of different factors, e.g. degree of lithiation of the active material, roughness of the electrode surface and temperature on the reaction rate is discussed. (C) 2001 Elsevier Science B.V. All righ ts reserved.