Alkali Chloride Coating for Graphite Electrode of Lithium-Ion Batteries

Abstract

Battery performance of a graphite electrode for negative electrodes of lithium-ion batteries was successfully enhanced by pretreatment of graphite powders with lithium, sodium, and potassium chloride aqueous solutions. In the process of the pretreatment, graphite powders were simply dispersed in the aqueous solutions and dried to coat the graphite powder with alkali chloride solid after filtration. When the optimum concentrations of each chloride, 0.1 wt % LiCl, 0.1 wt % NaCl, and 0.5 wt % KCl, were adopted for the pretreatment, the irreversible electroreduction capacity at the initial cycle was reduced by the chloride coating which was capable of modifying the solid electrolyte interphase formed on the graphite electrode surface, furthermore, the reversible capacity at a relatively high rate was improved by the coating from ∼320 to 340-350 mAh g-1 during successive cycles in a 1 mol dm-3 LiCl O 4 ethylene carbonate:diethyl carbonate electrolyte solution. The origins of the improvement were discussed from surface and electrochemical analyses. © 2010 The Electrochemical Society.