▎ 摘　　要

NOVELTY - Preparing graphene-coated magnesium oxide material MgO-C comprises (i) igniting magnesium strips or magnesium powder in a carbon dioxide atmosphere, collecting the ignited products and passing through a 50-800 mesh sieve to remove unreacted metal magnesium to obtain graphene-coated magnesium oxide material MgO-C, (b) placing magnesium strips or magnesium powder in a tube furnace, passing through a carbon dioxide atmosphere, and heating to 400-1000℃, and obtaining graphene-coated magnesium oxide material MgO-C with different particle sizes at different temperatures. USE - The magnesium oxide material is used as cathode material of metal-gas battery and in non-cathode gas battery and/or non-anode gas batteries (claimed). ADVANTAGE - The magnesium oxide material has excellent catalytic performance, and does not generate oxygen when charging, and avoids the need of oxygen in the environment. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: a gas battery prepared by the graphene-coated magnesium oxide material; graphene nano-cage material prepared by the graphene-coated magnesium oxide material; preparing metal-gas battery cathode sheet containing a graphene nanocage material or a composite nanocage structure catalytic material of graphene and metal,