Thermodynamics and kinetics of lithium intercalation into and deintercalation from lithium manganese oxide

Abstract

The present work involves the thermodynamics and kinetics of lithium intercalation into and deintercalation from the $LiMn_2O_4$ composite and film electrodes. In chapter III, the lithium intercalation into the $Li_{1-δ}Mn_2O_4$ 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. From the numerical calculation using the lattice gas model with the Bragg-Williams approximation, it was found that both lithium contents in two sub-lattices deviate strongly from that lithium content in total lattice due to the ordering of the intercalated lithium ions in the $Li_{1-δ}Mn_2O_4$ electrode. 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 of lithium ion were calculated at various lithium contents by a numerical method. The theoretical partial molar intercalation enthalpy and entropy of the lithium ion calculated by a numerical method are in good agreement with experimental results obtained from the temperature dependence of the electrode potential at various lithium contents. In chapter IV, the thermodynamics and kinetics of the lithium intercalation into $Li_{1-δ}Mn_2O_4$ electrode have been theoretically investigated underlain by the statistical thermodynamics concept using the Monte Carlo simulation based upon the lattice gas model. From the fluctuations in the internal energy and the number of lithium ions in the grand canonical ensemble (GCE), the partial molar internal energy and entropy of lithium ion were theoretically obtained at a fixed chemical potential. Both theoretic...