Electrochemical and Thermal Comparisons of Li[Ni[sub 0.1]Co[sub 0.8]Mn[sub 0.1]]O[sub 2] Synthesized at Different Temperatures (900, 1000, and 1100°C)

Abstract

The electrochemical properties of Li[Ni0.1Co0.8Mn0.1]O2synthesized at 900, 1000, and 1100°C were compared. Li[Ni0.1Co0.8Mn0.1]O2prepared 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]O2(900°C) 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 LiPF6EC/DEC than Li[Ni0.1Co0.8Mn0.1]O2samples prepared at either 1000 or 1100°C as measured by accelerating rate calorimetry. The onset temperature for the reaction of 100 mg Li[Ni0.1Co0.8Mn0.1]O2(900°C) charged to 4.2 V with 100 mg of 1 M LiPF6EC/DEC heated initially to 110°C is approximately 210°C, which is about 40°C higher than the onset temperature of the reaction between LiCoO2charged to 4.2 V and LiPF6EC/DEC electrolyte under the same conditions. © 2004 The Electrochemical Society. All rights reserved.