A fast and efficient pre-doping approach to high energy density lithium-ion hybrid capacitors

We demonstrate that the internal short (IS) approach is a fast and efficient process for lithium pre-doping in lithium-ion capacitors. Direct contact between the graphite electrode and lithium metal leads to very fast but controllable lithium pre-doping into graphite due to the large contacting area in the excess electrolyte medium, facilitating not only fast lithium intercalation into graphite but also fast dissipation of reaction heat generated during this process. LIC cells pre-doped through the IS method exhibit remarkably higher coulombic efficiency and longer cycle life than those of the cells prepared using conventional pre-doping methods such as electrochemical (EC) and external short circuit (ESC) methods. These results indicate that the IS pre-doping approach can significantly improve the anode manufacturing speed and reduce the cost of high energy density lithium-ion capacitors.