The complete experimental details on active material synthesis, electrode coating, and cell materials and assembly are provided in the supplemental information. Briefly, lithium cobalt oxide (LCO) was synthesized with a nominal composition of LiCo0.97Al0.02Ti0.005Mg0.005O2 through a molten salt reaction with a sodium sulfate flux, yielding single-crystal particles with an average size of ~ 3 μm. LCO electrodes were prepared by slurry coating onto carbon-coated Al foil. The coatings had a composition of 97.5 wt% AM, 1.0 wt% poly(vinylidene difluoride), 1.0 wt% carbon black, and 0.5 wt% vapor-grown carbon nanofibers. The electrode coatings had mass loadings of 1.2 -1.4 mg cm -2 and were calendared to a density of 3.9 -4.1 g cm -3 to achieve a coating thickness of ~ 3 μm. The electrolyte used for all experiments was 1.2 M LiPF6 + 0.1M LiPO2F2 + 0.1M lithium 4,5-dicyano-2-trifluoromethylimidazole (LiTDI) in a 25 : 75 w/w mixture of fluoroethylene carbonate (FEC) : dimethyl carbonate (DMC).