Thermal Characteristics of Li[sub x]Mn[sub 2]O[sub 4] Spinel

Abstract

The heat generation characteristics of spinel as a positive electrode material were measured in situ during cycling of cell, using an isothermal microcalorimeter in combination with a battery tester. The total heat generation rate is dependent on the concentration of lithium in By separating irreversible heat from the total heat rate, using dc interruption technique, the concentration dependence is shown to be mainly due to the reversible heat of the cell, which shows a cooling-heating-cooling-heating cycle, during charge/discharge. This thermal characteristic may be explained from the phase diagram of in agreement with recent reports on the phase-change behavior. The dependence of the thermal characteristics on the current level is weak at a low C rate, but increases steeply from C/3 to 1C rate. Although voltage profiles of charge and discharge showed similar behavior, the range of discontinuity (between 4.1 and 4.0 V) is not identical for charge and discharge. While the voltage profile is affected by irreversibility (charge vs. discharge), the thermal profile is barely affected by it. © 2001 The Electrochemical Society. All rights reserved.