Electrochemical and thermal comparisons of Li[Ni0.1Co0.8Mn0.1]O2 synthesized at different temperatures (900, 1000, and 1100°C)

The electrochemical properties of Li[Ni0.1Co0.8Mn0.1] O-2 synthesized at 900, 1000, and 1100degreesC were compared. Li[Ni0.1Co0.8Mn0.1] O-2 prepared at 900 has the largest reversible capacity of 170 mAh/g (charged to 4.4 V vs. Li metal) and retains 80% of its capacity after 200 cycles at C/4 in Li test cells. Furthermore, Li[Ni0.1Co0.8Mn0.1] O-2 (900degreesC) charged to either 4.2 or 4.4 V vs. Li metal shows less reactivity with ethylene carbonate (EC)/diethyl carbonate (DEC) solvent or with 1 M LiPF6 EC/DEC than Li[Ni0.1Co0.8Mn0.1] O-2 samples prepared at either 1000 or 1100 degreesC as measured by accelerating rate calorimetry. The onset temperature for the reaction of 100 mg Li[Ni0.1Co0.8Mn0.1] O-2 (900 degreesC) charged to 4.2 V with 100 mg of 1 M LiPF6 EC/DEC heated initially to 110 degreesC is approximately 210 degreesC, which is about 40 degreesC higher than the onset temperature of the reaction between LiCoO2 charged to 4.2 V and LiPF6 EC/DEC electrolyte under the same conditions. (C) 2004 The Electrochemical Society.