Thermodynamic Approach to Electrochemical Lithium Intercalation into Li1-δMn2O4 Electrode Prepared by Sol-Gel Method

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Abstract
Electrochemical lithium intercalation into Li1-δMn2O4 electrode prepared by sol-gel method was investigated from the thermodynamic view point by using galvanostatic intermittent titration technique (GITT) combined with EMF-temperature measurement. The electrode potential vs. lithium content curve was theoretically calculated with the aid of the lattice gas model based upon the Bragg-Williams approximation for the cubic spinel composed of two sub-lattices. Considering the considerable difference between both lithium contents in two sub-lattices due to the ordering of the intercalated lithium ions, the theoretical partial molar enthalpy and entropy were calculated at various lithium contents by a numerical method. From the comparison between the theoretical partial molar quantities and experimental results, the electrochemical lithium intercalation into the Li1-δMn2O4 electrode was discussed in terms of the ordering of the intercalated lithium ions.