Mechanical force inducing oxygen vacancies and pyrolysis gas reduction activity for the efficient valorization of waste biomass and Li-ion batteries

Abstract

Pyrolysis, thermal reduction, and mechanochemical force are commonly used for biomass utilization, materials synthesis, and spent Li-ion battery recycling. However, the effect of mechanical treatment on pyrolysis gas generation and thermal reduction remains unclear. Herein, we study the effect of mechanical treatment on the biomass pyrolysis reduction of LiCoO₂. Mechanical milling generates oxygen vacancies in the LiCoO₂ lattice. In addition, mechanical treatment can regulate the pyrolysis gas of sawdust in terms of increasing the content of H₂, CH₄, and CO while decreasing the CO₂ content. The oxygen vacancies and pyrolysis gas are beneficial for the thermal collapse of the LiCoO₂ structure, leading to the rapid and complete separation of Li and Co, thereby increasing the recovery efficiency to above 98%. The understanding of the interplay of mechanical force, oxide structure, and pyrolysis gas composition helps design green approaches for enabling metal and organic resource recovery and utilization.