Alkali carbonate-coated graphite electrode for lithium-ion batteries

Charge and discharge behavior of a graphite electrode for rechargeable lithium-ion batteries was successfully improved by pretreatment of graphite powders with A(2)CO(3) (A = Li, Na, and K) aqueous solutions. In the process of the pretreatment, graphite powders were simply dispersed in the aqueous solutions, and then filtered and dried to modify the surface of graphite powder with solid alkali carbonate. With the optimum concentration of each carbonate, 1 wt.% Li2CO3, 5 wt.% Na2CO3, and 1 wt.% K2CO3, the irreversible reaction at the initial cycle was suppressed by the pretreatment which was capable of modifying the solid electrolyte interphase formed on the graphite electrode surface. Furthermore, the rate capability was improved by the surface modification, that is, the reversible discharge capacities at 175 mA g(-1) increased with adequate capacity retention in a 1 mol dm(-3) LiClO4 ethylene carbonate: diethyl carbonate electrolyte solution because of the kinetics enhancement of lithium-ion transfer at the interface. (C) 2008 Elsevier Ltd. All rights reserved.