Waste to Wealth Approach: Customizing Spent LiB Anodes to High Performance Supercapacitor Electrode

Abstract

Lithium‐ion batteries (LiBs) are widely used in various applications because of their high energy density, low self‐discharge rate, and portability. The requirements for LiBs continue to increase drastically every year; however, the disposal of spent LIBs is a cumbersome task. To resolve this issue, spent LiB anodes are customized into high‐performance supercapacitor (SC) electrodes via supercritical water exfoliation. The specific capacitance of spent LiB anodes (289 F g−1 at 2 A g−1) significantly improved after exfoliation (351 F g−1 at 2 A g−1). Furthermore, the electrochemical performance of the exfoliated LiB anode mushroomed upon the addition of dopamine (as a redox‐additive for the first time) with a conventional H2SO4 electrolyte. The specific capacitance of the exfoliated LiB anode is incredibly improved after the addition of dopamine with H2SO4, from 286 to 571 F g−1 at 4 A g−1. A flexible SC is also fabricated using PVA/H2SO4 and dopamine/PVA/H2SO4 as the gel electrolyte. The fabricated flexible SC with dopamine/PVA/H2SO4 exhibited an enormously high energy density of 44 Wh kg−1 at 700 W kg−1. The increased specific capacitance and energy density of the SC after the addition of dopamine with H2SO4 and PVA/H2SO4 may be due to the reversible reaction of dopamine to dopamine‐o‐quinone with H+ ions.