In order to address the issue of Ni2+ and Co2+ pollution in lithium-ion battery waste, a novel biochar adsorption material utilizing aloe peel as the raw material has been developed. The fabrication of this biochar involves the incorporation of (NH4)2SO4 as a nitrogen and sulfur source to prepare a carbon precursor via hydrothermal synthesis, followed by the pyrolysis process at different final temperatures to produce N, S co-doped biochar (NSBCx). The resulting NSBCx material was characterized using techniques such as SEM, N2 adsorption-desorption, XPS, and ZETA potential analysis to evaluate its adsorption capacity for Ni2+ and Co2+ in the waste solution. The results show that the surface of NSBCx is exposed with complex lamellar stacking porous structure, with NSBC800 synthesized at an activation temperature of 800 °C displaying a hierarchical porous structure, a non-microporous proportion of 46%, a micropore volume of 0.07 cm3/g, and a specific surface area of 149 m2/g. Furthermore, NSBC800 surface was found to contain a significant amount of oxygen (29.94%), nitrogen (4.79%), and sulfur (6.21%) elements, with adsorption capacities of 245.10 mg/g for Ni2+ and 223.71 mg/g for Co2+. The chemical functional groups consisting of oxygen, nitrogen, and sulfur elements on the surface of NSBC800 underwent significant changes after adsorbing Ni2+ and Co2+, and these functional groups were able to react with metal ions to form salts or complexes, depositing on the biochar surface. The adsorption process of NSBCx for Ni2+ and Co2+ was found to be better described by the Langmuir model and pseudo-second-order kinetic model, with the adsorption process being chemisorption-controlled. Multiple mechanisms including chelation, co-precipitation, ion exchange, and electrostatic attraction were identified to simultaneously remove Ni2+ and Co2+ from the waste solution.