Development of non-flammable lithium secondary battery with ambient-temperature molten salt electrolyte: Performance of binder-free carbon-negative electrode

Abstract

The performance of a binder-free carbon-negative electrode was investigated using the LiCl-saturated AlCl 3–1-ethyl-3-methylimizadolium chloride (EMIC) + SOCl 2 melt as the electrolyte for non-flammable lithium secondary batteries. Because the glass transition point of a LiCl-saturated 60.0 mol%AlCl 3–40.0 mol%EMIC + 0.1 mol l −1 SOCl 2 melt was −86.2 °C, the melt could be used as the electrolyte in a low-temperature domain. The binder-free carbon electrode made by the electrophoretic deposition method was used as the negative electrode. Four kinds of carbon materials, i.e., artificial graphite, natural graphite, soft carbon, and hard carbon were evaluated as the carbon electrode. For 30 cycles, the discharge capacities of these electrodes were 296–395 mAh g −1 and the charge–discharge efficiencies were more than 90%. The melt can be used as the electrolyte for non-flammable lithium secondary batteries and the binder-free carbon-negative electrode operates quite effectively.