Thermal study on single electrodes in lithium-ion battery

The thermodynamic parameters: AG, AS and Delta H of LixC6/1 M LiPF6/Li1-xCoO2 battery reaction were measured by potentiometric method. The AS and reversible Peltier heat q(r) of cathode and anode reactions in lithium-ion battery were calculated from the Delta S of Li/1M LiPF6/Li1-xCoO2 and Li/1 M LiPF6/LixC6 cell reactions, and the Delta S of Li electrode reaction, respectively. For Li electrode reaction, the AS and q(r) were detected by both potentiometric and electrochemical-calorimetric methods. For a fully charged LixC6/1 M LiPF6/Li1-xCoO2 battery during reversible discharge process, the overall reaction Li1-xCoO2+LixC6 -> LiCoO2+6C presents exothermal heat effect with Delta S of -29.78J K-1 mol(-1) and q(r) of 8.874 kJ mol(-1). Furthermore, the cathode reaction xLi(+) +xe(-) + Li1-xCoO2 -> LiCoO2 shows larger exothermic effect with Delta S of -121.8 J K-1 mol(-1) and q(r) of 36.30 kJ mol(-1), and the anode reaction LixC6 -> xLi(+) +xe(-) +6C shows smaller endothermic effect with Delta S of 92.08 J K-1 mol(-1) and q(r) of -27.46 U mol(-1). The heat produced at the positive electrode reaction is about three times more than that of overall battery reaction. (c) 2005 Elsevier B.V. All rights reserved.