In Situ Studies of Li[sub x]Mn[sub 2]O[sub 4] and Li[sub x]Al[sub 0.17]Mn[sub 1.83]O[sub 3.97]S[sub 0.03] Cathode by IMC

Abstract

Thermal profiles of LiMn2O4LiMn2O4 and LiAl0.17Mn1.83O3.97S0.03LiAl0.17Mn1.83O3.97S0.03 were investigated with electrochemical-calorimetric technique. The heat contributions are discussed in terms of reversible and irreversible heat generation. The endothermic and exothermic heat profiles observed during the charge and discharge processes are related to the Li insertion/extraction reactions in the spinel host structure for both materials. The reversible heat generation is estimated on the basis of the cell entropy change. The heat generation calculated from ΔSΔS and the open-circuit potential results are consistent with the heat profile (exothermic/endothermic) generated during the charge/discharge process and with the magnitude of the heat generation from the experimental results obtained from the isothermal microcalorimetry (IMC) at a slow charge/discharge rate. The irreversible heat generation dependence on the current is discussed at different discharge currents. The calculated results show good consistency with the experimental data. © 2005 The Electrochemical Society. All rights reserved.