The irreversible capacity mainly comes from the irreversible reactions of the inserted Li + ions with the glass anodes and the formation of solid electrolyte interface (SEI). In the following 50, 100 and 200 cycles, the voltage profiles share almost the same shape and the specific capacities decreases only slightly, such as 505, 484 and 440 mA h g -1 , respectively, confirming the reversibility of the lithium storage reaction at a high current density.