Applications of Different Biomass in the Recycling of Spent Lithium-Ion Batteries

In the context of carbon neutrality and energy transition, the global scale-up and deployment of new energy vehicles (NEVs) are accelerating in terms of both quality and pace. Among the critical power sources for NEVs, lithium-ion batteries stand out as a key component. However, due to degradation, the management of spent batteries poses growing challenges. Simultaneously, in alignment with the strategic objectives of "carbon peak and carbon neutrality", the recyclability of waste materials has attracted widespread interest. Despite this, the recycling of certain biomass waste, such as bamboo powder, kitchen and fruit waste, bagasse, tea leaves, and coffee grounds, faces numerous obstacles. This paper provides a comprehensive review of the application of various waste materials in the recycling of lithium-ion batteries, including reaction mechanisms, pathways, and practical value. Specifically, straw is predominantly used as a reducing agent in acid leaching systems, for the production of biochar, and for the generation of reducing gases. Kitchen waste, exemplified by orange peels, is primarily utilized for the preparation of citric acid, serving as both leaching and reducing agents. Bagasse is mainly employed for the production of glucose as a reducing agent and for the generation of reducing gases. Polyphenols in tea residues can reduce metals within lithium-ion batteries. Furthermore, biomass generates a significant amount of reducing gases during the calcination process, which can enhance the efficiency of reactions by introducing gas-solid interactions into the calcination system. Additionally, the introduction of biochar can effectively reduce carbon emissions in the production process, endowing biomass with unique advantages as a reducing agent in calcination. The extraction of reducing substances or organic acids from biomass can serve as alternatives to environmentally unfriendly reducing agents, such as sodium thiosulfate or inorganic acids, used in hydrometallurgical reduction processes, thereby mitigating the potential environmental impact associated with the recycling of spent lithium-ion batteries. Recycling spent lithium-ion batteries with waste materials circumvents the costs and environmental hazards associated with conventional biomass disposal or recycling. This approach offers a viable strategy for the recycling of spent lithium-ion batteries, holding substantial practical value. Based on state-of-the-art research, this paper evaluates various approaches to recycling lithium-ion batteries using waste materials and provides perspectives and recommendations on the application of different types of waste in the recycling process. The paper also discusses the limitations and countermeasures of using biomass waste in lithium-ion battery recycling, offering new insights into the organic integration of the waste resource industry with the lithium-ion battery recycling sector.