Nanometer MnO/porous biochar lithium battery negative electrode material and preparation method thereof

The invention discloses a nanometer MnO/porous biological carbon lithium battery negative electrode material which is characterized in that MnO nanometer particles are attached to an amorphous biological carbon frame structure containing oxygen and nitrogen, and the biological carbon frame is obtained by calcining and carbonizing fresh grapefruit peel and flesh after a hydrothermal reaction. The invention also discloses a preparation method of the material. The preparation method comprises the following steps: dissolving manganese nitrate and urea in distilled water according to a certain proportion to form a clear solution A; soaking inner flesh blocks of fresh grapefruit peels in the clear solution A, and sealing and heating for hydrothermal reaction; and taking out the product after the hydrothermal reaction, evaporating the contained solution to dryness, calcining the product after evaporation to dryness under the protection of N2, and naturally cooling to room temperature to obtain the nano MnO/porous bi