A study of methyl phenyl carbonate and diphenyl carbonate as electrolyte additives for high voltage LiNi0.8Mn0.1Co0.1O2/graphite pouch cells

The effectiveness of methyl phenyl carbonate and diphenyl carbonate as electrolyte additives either singly or in combination with methylene methyl disulfonate and tris(-trimethyl-silyl)-phosphite has been systematically investigated in LiNi0.8Mn0.1Co0.1O2/graphite pouch cells. Experiments conducted included ultrahigh precision coulometry, electrochemical impedance spectroscopy, automated storage, gas evolution measurements as well as long-term cycling. The results showed that adding methyl phenyl or diphenyl carbonate increases the coulombic efficiency, reduces charge end-point capacity slippage rate, decreases the self-discharge rate during storage and improves the capacity retention during long-term cycling compared to cells with control electrolyte [1 M LiPF6 ethylene carbonate:ethyl methyl carbonate 3:7] or control electrolyte with 2% vinylene carbonate. 1% diphenyl carbonate appears to be the best among the systems studied. Based on these experiments, diphenyl carbonate seems to be a very beneficial additive for improving the performance of high voltage LiNi0.8Mn0.1Co0.1O2/graphite pouch cells. (C) 2016 Elsevier B.V. All rights reserved.