▎ 摘　　要

NOVELTY - A heterojunction membrane material comprises 5-80 wt.% graphene nanosheet and 20-95 wt.% stannous sulfide nanosheet. USE - The heterojunction membrane material is used for preparing negative electrode of sodium metal battery (all claimed). ADVANTAGE - The heterojunction membrane material has improved cycle life and safety of the sodium metal cathode. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) battery diaphragm comprising graphene/stannous sulfide two-dimensional heterojunction composite material film, which is formed by two-dimensional stacking composite depositing graphene nanosheet and stannous sulfide nanosheet on the surface of the battery diaphragm; (2) sodium metal battery cathode comprising sodium metal electrode sheet and battery diaphragm; (3) sodium metal battery comprising sodium metal electrode, electrolyte and battery diaphragm; and (4) preparation of composite material comprising dispersing the graphene nanosheet into isopropanol aqueous solution, ultrasonically dispersing at room temperature, gradually adding poly diallyl dimethyl ammonium chloride solution, centrifugal separating, and re-dispersing precipitate in deionized water; dispersing stannous sulfide nanosheet into isopropanol aqueous solution ultrasonically dispersing at room temperature, gradually adding modified graphene dispersion, and stirring; and filtering or spraying to form a film on the battery membrane and forming The battery diaphragm is a polyolefin battery diaphragm. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the heterojunction membrane material.