TY  - JOUR
AU  - Buchheit, Annika
AU  - Grünebaum, Mariano
AU  - Teßmer, Britta
AU  - Winter, Martin
AU  - Wiemhöfer, Hans-Dieter
TI  - Polycarbonate-Based Lithium Salt-Containing Electrolytes: New Insights into Thermal Stability
JO  - The journal of physical chemistry  / C
VL  - 125
IS  - 8
SN  - 1932-7455
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2021-01222
SP  - acs.jpcc.0c09968
PY  - 2021
AB  - For investigation of the thermal stability of polycarbonate-based lithium salt-containing electrolytes, polycarbonate–salt mixtures [polyethylene carbonate (PEC) and polypropylene carbonate (PPC) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)] were heated to 100 °C and the conductivity was monitored with electrochemical impedance spectroscopy for at least 24 h. At a constant high temperature, the observed rise in conductivity can be correlated to degradation of long-chain polymer units to small-chain polymer units as the viscosity decreases with a shorter chain length. In both cases, degradation can be observed. With PEC–LiTFSI, it takes ≈9 h until total degradation; with PPC–LiTFSI, the process is slower. Additionally, we repeated the experiments with PEC and other Li salts such as lithium trifluoromethanesulfonate (LiOTf), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), and lithium difluoro(oxalato)borate (LiDFOB). These experiments resulted in the degradation being dependent on the electrophilic activation by the lithium salt. With different Li-free salts such as sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), potassium bis(trifluoromethanesulfonyl)imide (KTFSI), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr14TFSI), no degradation of the polymer is observable. As a degradation mechanism, we anticipate a depolymerization of PEC at the α-carbon of the carbonate group in the polymer chain in the presence of a lithium salt with a weakly coordinating anion.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000626769100007
DO  - DOI:10.1021/acs.jpcc.0c09968
UR  - https://juser.fz-juelich.de/record/890814
ER  -