Because of an improved mass transfer process, chemical energy in a liquid phase, which has been absorbed into the micro-pores of porous electrodes, may be electrochemically converted into electrical energy at a high rate and with a long cycle life. Based on this principle, we demonstrated methods for a new electrochemical storage device, which had higher specific power, a much longer cycle life than existing storage batteries and a greater specific energy than existing supercapacitors. Even at the high current rate of 80 C for deep charge/discharge, a long cycle life (30,000) and good utilization efficiency have been achieved. This new device may be developed into a new family of energy storage systems with a variety of applications. The first important practical application could be on-board, rechargeable electric energy storage devices for electric vehicles. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3556586] All rights reserved.