New Generation High Performance Lithium-Ion Capacitor Laminate Cells

Abstract

In recent years considerable research has been focused on the development of high energy density EC capacitors. Among all the energy storage systems that have been investigated and developed in the last few years, Lithium-ion Capacitors (LICs) have emerged to be one of the most promising because LICs achieve higher energy density than conventional Electric Double-Layer Capacitors (EDLCs), and better power performance than Li-ion batteries (LIBs) as well being capable of long cycle life which is shown in Fig. 1. LICs contain a pre-lithiated LIB anode electrode and an EDLC cathode electrode. Previously, we have reported a LIC with activated carbon (AC) cathode and hard carbon (HC)/stabilized lithium metal powder (SLMP) anode electrodes with high energy density, high power density and long cycle life1-7. From all the study before, we have achieved a high energy density LIC pouch cell4 with an energy density as high as 30 Wh kg-1 but only with a usable specific power of about 1.0 kW kg-1 and a maximum specific power of 2.0 kW kg-1. Therefore in this paper, we wish to report new generation high performance LIC laminate cells with higher power density and longer cycle life by sacrificing the energy density of the cells. The low temperature performance of the LIC laminate cells is also included in this paper. It can be concluded from the following data figures (from Fig. 2 to Fig. 4) that the specific energy and energy density as high as 20 Wh kg-1 and 38 Wh L-1 have been achieved, respectively. The laminate cells obtained a maximum specific power of 7.8 kW kg-1, respectively. The developed LICs can operate in a temperature as wide as from -40 degree C to +70 degree C. After 50,000 cycles, the LIC laminate cells still have 92% of the initial discharge capacity.