High‐performance Li‐ion capacitor via anion‐intercalation process

Abstract

Abstract Supercapacitors are characterized by their fast charge/discharge capability, high‐power capability, and long cycle life, but low‐energy‐density impedes their practical application. The requirement of achieving a highly efficient energy storage system demands the hybridization of supercapacitors and batteries. The anion‐intercalation chemistry of graphite with high insertion potential creates a possibility of using graphite as a cathode, which works as an acceptor‐type graphite intercalation compound. Herein, we report the reversible PF6– anion storage on the graphite cathode, which occurs by the combination of pseudocapacitive and diffusion‐limited redox reaction at a higher working potential. Furthermore, a dual carbon lithium‐ion capacitor (LIC) using commercial graphite as anion‐intercalation type, battery type cathode, and commercial‐activated carbon (AC) as supercapacitor type anode is designed. The assembled preanion intercalated Graphite/AC‐based LIC assembly displayed a high‐energy density of 90.73 Wh kg–1. Moreover, the device with low‐temperature stability is advantageous over traditional electrical double‐layer capacitors, mainly in terms of its energy and low cost with much more safety features than commercial lithium‐ion batteries.

Keywords

• anion intercalation
• dual carbon Li‐ion capacitor
• energy density
• graphite cathode