AC/Se composite cathode for asymmetric Li-ion capacitors

Abstract

The asymmetric capacitors are one of the energy storage systems that provide high energy density and high power density. However, there are some limitations which impede the development of asymmetric capacitors. In this context, we designed a new type of lithium-selenium asymmetric capacitor (LSEC) that has both the capacitive effect and the diffusion-controlled reaction. The LSECs use the activated carbon-selenium (AC-Se) as a mixed cathode material and the pre-lithiated graphite as an anode material which can exhibit the electrochemical reduction/oxidation of Se and the adsorption/desorption of anions at substantially the same rate. This novel LSEC solves the problem of imbalance between the energy and the dynamics, and provides a solution to provide both high energy density and high power density, thus has great application potential.