On the use of 3-cyanopropionic acid methyl ester as alternative solvent for high voltage dual carbon lithium ion capacitors

In this work we report for the first time the use of 3-cyanopropionic acid methyl ester (CPAME), with vinylene carbonate (VC) as additive, as an alternative solvent when targeting high voltage lithium ion capacitors (LICs). In view of the promising viscosity, conductivity, and electrochemical stability window, its use in LICs is explored. To this end, a hard carbon (HC) is selected as the negative electrode, while an activated carbon (AC) is the preferred choice as the positive electrode, both being biomass (olive-pits) waste derived. The electrochemical characterization of the HC shows good specific capacities at both low and high current densities (e.g. 322 mAh g(-1) at C/10 and 80 mAh g(-1) at 10C). In addition, the cyclic voltammogram of the AC reveals a stable electrochemical potential window rising to 4.6 V vs. Li+/Li. This fact allows to develop a LIC operating at 1.5-4.5 V able to deliver high energy and high power density values (i.e. 121 Wh kg(AM)(-1) at 299 W kg(AM)(-1) and 69 Wh kg(AM)(-1) at 2217 W kg(AM)(-1)).