Fluorine modification regulation of D-A ambipolar conducting polymers towards high-performance energy storage device

Abstract

Fluoride modulation is a commonly employed molecular design technique that has the capability to alter the energy level of a molecule and enhance intermolecular interaction in various fields. However, the impact of fluorinated modified molecules, serving as electrode materials, on electrochemical performance requires further investigation and clarification. In this work, we have developed a range of ambipolar conducting polymers with varying quantities and positions of fluorinated modified phthalimides as the fundamental acceptor unit. We have thoroughly examined their individual regulatory mechanisms and assessed their effects on electrochemical energy storage. It was discovered that increasing the number of fluorine modifications, leads to a decrease in the LUMO energy level. The impact of fluorine modification position is more significant when it is positioned near the carbonyl group. This is because the electron cloud density around the carbonyl group is affected, weakening its ability to coordinate with lithium ions. Based on this design, a conductive polymer called PEPF2, with two fluorine atoms modifying phthalimide, was developed. PEPF2 exhibits excellent properties, including a negative capacitance of up to 63F/cm3 at 5 A/cm3.