▎ 摘　　要

NOVELTY - Preparing reduced graphene oxide involves freeze drying an aqueous solution containing graphene oxide to obtain graphene oxide aerogel, and self-propagating combustion of the graphene oxide to obtain the reduced graphene oxide. USE - Method for preparing reduced graphene oxide. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a method for preparing a graphene film, preparing reduced graphene oxide, and compressing the reduced graphene oxide into a film to obtain the graphene film; (2) a battery positive electrode, which comprises a graphene film; and (3) a aluminum ion battery, which comprises battery positive electrode, a negative electrode and an electrolyte, where the electrolyte includes 1-ethyl-3-methylimidazolium chloride and trichloride aluminum.