Eliminating pre-lithiation step for making high energy density hybrid Li-ion capacitor

Pre-lithiation is an indispensable step for making hybrid lithium-ion capacitors (LICs), its high cost and process complexity have greatly hindered the commercialization of LICs. Aiming to eliminate the prelithiation step, we propose an in-situ lithiation concept by introducing a Li+ ion source material into the positive electrode to enable the lithiation to be completed in the formation cycle. In this paper we start with the fundamental principle of LICs to discuss the requirements for Li+ ion source materials and demonstrate this concept by employing Li-rich Li2CuO2 as the Li+ ion source material, natural graphite and activated carbon (AC) as the negative and positive electrode materials. It is shown that the LICs made such behave as a pure capacitor with ability to deliver the same level of specific capacity and specific capacitance, i.e., 56 mAh g(-1) and 143 F g(-1) vs. the mass of AC in the voltage range between 2.8 V and 4.2 V, as those obtained from the counterpart Li/AC half-cell. The present concept is also applicable to other LICs with the negative electrode required to be pre-lithiated. Published by Elsevier B.V.