ARC studies of the reaction between Li0FePO4 and LiPF6 or LiBOB EC/DEC electrolytes

Accelerating Rate Calorimetry (ARC) has been used to study the reaction between Li0FePO4 having an average particle size of 3, 7 or 15 mum with EC/DEC solvent, 1.0 M LiPF6 EC/DEC or 0.8 M lithium bis(oxalato)borate (LiBOB) EC/DEC electrolyte. LiFePO4 electrode material was charged to 3.8 V vs. Li metal to produce Li0FePO4 before analysis. In EC/DEC solvent, all the three Li0FePO4 samples show high thermal stability and their ARC onset temperature is higher than 300 degreesC. As the particle size of Li0FePO4 increases from 3-7 to 15 mum, the self-heating rate (SHR) with EC/DEC solvent at the same temperature becomes slightly lower. With the addition of LiPF6 to EC/DEC, self-heating exotherms begin at approximately 190 degreesC for all the three Li0FePO4 samples, independent of particle size. LiBOB-based electrolyte shows higher thermal stability than LiPF6-based electrolytes for all the three Li0FePO4 samples. Self-heating exotherms for the three Li0FePO4 samples in 0.8 M LiBOB EC/DEC begin at about 240 degreesC. (C) 2004 Elsevier B.V. All rights reserved.