Expanded graphite and preparation method therefor

A preparation method for an expanded graphite, comprising the following steps:

• (1) mixing a graphite powder with a metal peroxide and/or an alkali metal superoxide under a protective atmosphere, and leaving the mixture to stand still, to obtain a mixed graphite-metal peroxide and/or graphite-alkali metal superoxide composite material;
• (2) putting the composite material prepared in step (1) into a liquid medium capable of reacting with the metal peroxide and/or the alkali metal superoxide for reacting, to obtain an intercalated graphite;
• and
• (3) heating the intercalated graphite prepared in step (2) to prepare the expanded graphite,
• wherein the metal peroxide is at least one of CaO2, K2O2, Na2O2 and Li2O2;
• the alkali metal superoxide is at least one of KO2 and NaO2;
• and
• a mass ratio of the graphite powder to the metal peroxide and/or the alkali metal superoxide in step (1) is (1 to 20):1.