Open AccessA Study of Vinylene Carbonate and Prop-1-ene-1,3 Sultone Electrolyte Additives Using Polycrystalline Li[Ni0.6Mn0.2Co0.2]O2 in Positive/Positive Symmetric Cells
Author(s) -
Yulong Liu,
Ines Hamam,
J. R. Dahn
Publication year - 2020
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/aba36a
Subject(s) - electrolyte , electrode , diethyl carbonate , chemistry , open circuit voltage , crystallite , analytical chemistry (journal) , carbonate , voltage , materials science , ethylene carbonate , electrical engineering , chromatography , crystallography , organic chemistry , engineering
Vinylene carbonate (VC) and prop-1-ene-1,3 sultone (PES) have been reported to have beneficial effects on both negative and positive electrodes of Li-ion cells. To simplify evaluation of these two additives with LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622), positive/positive symmetric cells were used to exclude the influence from any negative electrode. The compatibility of electrolytes containing 2%VC or 2%PES with NMC622 in 1M LiPF 6 EC:DEC (v/v 1:2) electrolyte was evaluated by multiple voltage hold periods at 55 °C to accelerate the capacity fade. EIS spectra showed 2%PES is superior for impedance control compared to 2%VC. dV/dQ vs V fitting results showed that active mass loss is worse at high voltage than low voltage regardless of electrolyte used. Cross-sectional SEM images showed more microcracking of NMC622 particles at high voltage than at low voltage, which was more severe at the end of testing than at the beginning of testing. Symmetric cell storage at 0 V (ca. 3.8 V vs Li/Li + ) and 0 °C showed a significant increase in cell impedance for cells stored after the end of testing and a moderate impedance increase for cells stored at the beginning of testing suggesting the accumulation of deleterious reaction products in the cells during testing.