This work was intellectually led by the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy sciences (BES), under Contract No. DEAC02-06CH11357. Electrolyte synthesis and characterization work was performed by L. S. G., D. B. S., and H. Q. N. under the supervision of N. P. B.; L. S. G. under the supervision of H. C.; and K. M. D. under the supervision of B. D. M. We thank UC Berkeley's NMR facility in the College of Chemistry (CoC-NMR) for spectroscopic assistance.