Analysis of Capacity Fade from Entropic Heat Coefficient of Li[NixCoyMnz]O2/Graphite Lithium Ion Battery

The entropic heat coefficient (i.e., dU/dT) of Li[NixCoyMnz]O-2/graphite before and after cycle was determined using the electrochemical thermodynamics measurements (ETMs) tool. DU/dT could be attributed to the individual electrodes for this notable battery and associates with the Li-intercalated state. Lithium intercalation number in negative and positive electrode was calculated and compared for the battery before and after cycle, respectively. Results show that the trend of dU/dT with Li-intercalated state before and after cycle is basically consistent except for the initial and maximum state. DU/dT has the typical characteristics of stage structures of graphite. In particular, these changes is independent of the battery aging. Negative electrode has greater Li-intercalated depth loss than that of positive electrode after cycle, thus negative electrode is the dominant degradation factor of the battery. (C) 2016 The Electrochemical Society. All rights reserved.