Lithium-ion pre-doping of graphite electrodes using lithium naphthalenide derivatives with electron-donating substituents

Abstract

The effect of the molecular structure of lithium naphthalenide derivatives on the degree of lithium pre-doping was assessed, as part of a simple pre-doping method for natural graphite electrodes. The method involves immersion in a 2-methyltetrahydrofuran (2-MeTHF) solution of lithium naphthalenide derivatives. To increase the reducing ability of lithium naphthalenide, we tested various naphthalene derivatives with electron-donating substituents on the aromatic ring. The results showed that a radical anion solution prepared from 1 mol kg⁻¹ 1,5-dimethylnaphthalene in 2-MeTHF, combined with an excess of lithium metal, achieved a degree of lithium pre-doping of 88 mAh g⁻¹ after 1 h of immersion at room temperature. This method could potentially serve as a pre-doping technique for the negative electrodes in electrochemical energy storage devices.