A Self-Charging Aluminum Battery Enabled by Spontaneous Disproportionation Reaction

Abstract

Herein, a self-charging mechanism of rechargeable aluminum (Al) batteries with Chevrel phase molybdenum sulfide (Mo6S8) cathode is reported. The results unambiguously reveal that the self-charging is a spontaneous disproportionation of Al intercalated Mo6S8 originated from the dynamic shift of Al between occupied sites during Al intercalating and resting. The theoretical study indicates that the fully Al intercalated Mo6S8 in the format of Al4/3Mo6S8 is kinetically accessible driven by electrochemical overpotential but thermodynamically unstable due to the repulsion between Al3+ cations. This mechanism is a true self-charging with no input of any form of energy, thus distinctly superior to the previously reported self-charging mechanisms. Based on this discovery, a semi-flow AlMo6S8 battery is designed and demonstrated with long-lasting discharge capability and high capacity.