Preparation method of in-situ sulfur and nitrogen codoped biomass carbon nanosheet

The invention discloses a preparation method of an in-situ sulfur and nitrogen codoped biomass carbon nanosheet. The preparation method of the in-situ sulfur and nitrogen codoped biomass carbon nanosheet comprises the following steps of processing raw materials; grinding and mixing a nitrogen source and a sulfur source into processed bean dregs, burning the mixed product in an inert atmosphere inside a reactor; performing product impurity removal. The preparation method of the in-situ sulfur and nitrogen codoped biomass carbon nanosheet is simple and saves time; the raw materials are biomass waste which are easy and rich to acquire; compared with other carbon materials prepared through biomass source modification, the prepared in-situ sulfur and nitrogen codoped biomass carbon nanosheet isbetter in structure, namely, is in a layered carbon nanosheet structure, which can to a large degree improve the electrochemical performance of batteries when applied to lithium-sulfur battery positive electrode materials; m