Provided is a method of improving fast-chargeability of a lithium secondary battery containing an anode, a cathode, a porous separator disposed between the anode and the cathode, and an electrolyte, wherein the method comprises packing particles of an anode active material to form an anode active material layer having interstitial spaces and disposing a lithium ion reservoir in the interstitial spaces, configured to receive lithium ions from the cathode through the porous separator when the battery is charged and to enable the lithium ions to enter the particles of anode active material in a time-delayed manner.