The use of two additives each with a specific role, with one providing lithium ions and the other electrons, offers much greater latitude, for they can be selected independently for their price, chemical properties, and performance. When a lithium-ion capacitor is charging, the first additive (pyrene, naturally present in certain types of coal) releases electrons and protons. The second additive, Li3PO4 (mass produced in the glass industry, for instance), captures these protons, and in turn releases lithium ions that are then available for prelithiation.
An additional advantage of this approach to building lithium ion capacitors is that after prelithiation, the residue of one of the two additives used, pyrene, contributes to the storage of charges, thereby increasing the quantity of electrical energy stored in the device. The efficiency and versatility offered by this new approach opens the way for an inexpensive solution for prelithiation, resulting in lithium-ion capacitors that can store more energy. The breaking of this technological barrier should therefore enable a quicker commercialisation of these devices.