TY - JOUR
T1 - Thermal aging of electrolytes used in lithium-ion batteries – An investigation of the impact of protic impurities and different housing materials
AU - Handel, Patricia
AU - Fauler, Gisela
AU - Kapper, Katja
AU - Schmuck, Martin
AU - Stangl, Christoph
AU - Fischer, Roland
AU - Uhlig, Frank
AU - Koller, Stefan
PY - 2014
Y1 - 2014
N2 - Thermal degradation products in lithium-ion batteries result mainly from hydrolysis sensitivity of lithium hexafluorophosphate (LiPF6). As organic carbonate solvents contain traces of protic impurities, the thermal decomposition of electrolytes is enhanced. Therefore, resulting degradation products are studied with nuclear magnetic resonance spectroscopy (NMR) and gas chromatography mass spectrometry (GC–MS). The electrolyte contains 1 M LiPF6 in a binary mixture of ethylene carbonate (EC) and diethylene carbonate (DEC) in a ratio of 1:2 (v/v) and is aged at ambient and elevated temperature. The impact of protic impurities, either added as deionized water or incorporated in positive electrode material, upon aging is investigated. Further, the influence of different housing materials on the electrolyte degradation is shown. Difluorophosphoric acid is identified as main decomposition product by NMR-spectroscopy. Traces of other decomposition products are determined by headspace GC–MS. Acid–base and coulometric titration are used to determine the total amount of acid and water content upon aging, respectively. The aim of this investigation is to achieve profound understanding about the thermal decomposition of one most common used electrolyte in a battery-like housing material.
AB - Thermal degradation products in lithium-ion batteries result mainly from hydrolysis sensitivity of lithium hexafluorophosphate (LiPF6). As organic carbonate solvents contain traces of protic impurities, the thermal decomposition of electrolytes is enhanced. Therefore, resulting degradation products are studied with nuclear magnetic resonance spectroscopy (NMR) and gas chromatography mass spectrometry (GC–MS). The electrolyte contains 1 M LiPF6 in a binary mixture of ethylene carbonate (EC) and diethylene carbonate (DEC) in a ratio of 1:2 (v/v) and is aged at ambient and elevated temperature. The impact of protic impurities, either added as deionized water or incorporated in positive electrode material, upon aging is investigated. Further, the influence of different housing materials on the electrolyte degradation is shown. Difluorophosphoric acid is identified as main decomposition product by NMR-spectroscopy. Traces of other decomposition products are determined by headspace GC–MS. Acid–base and coulometric titration are used to determine the total amount of acid and water content upon aging, respectively. The aim of this investigation is to achieve profound understanding about the thermal decomposition of one most common used electrolyte in a battery-like housing material.
UR - http://www.journals.elsevier.com/journal-of-power-sources/
UR - http://www.sciencedirect.com/science/article/pii/S0378775314007721
U2 - 10.1016/j.jpowsour.2014.05.080
DO - 10.1016/j.jpowsour.2014.05.080
M3 - Article
SN - 1873-2755
VL - 267
SP - 255
EP - 259
JO - Journal of Power Sources
JF - Journal of Power Sources
ER -