The world’s fast-growing fleet of electric vehicles and the rapid replacement of smartphones, laptops, and other electronic devices are creating a looming waste challenge: millions of lithium-ion batteries approaching the end of their useful lives. Inside these batteries are valuable metals such as lithium, cobalt, nickel, manganese, copper, and aluminum—materials that could form a major “urban mine” if recovered efficiently. Yet the same batteries can become a source of chemical, ecological, and safety risks when they are dismantled, transported, or discarded without proper controls. A new review from researchers at North China University of Science and Technology maps the technologies that could determine whether spent lithium-ion batteries become an environmental liability or the foundation of a circular materials economy.
Published in Materials Reports: Solidwaste and Ecomaterials, the study, titled “A systematic review of valuable resource recovery from spent lithium-ion battery cathodes: Technologies, challenges, and future trends,” examines the field through a framework that connects data, mechanisms, and industrial systems. Led by Jianqiu Qin and supervised by Associate Professors Shaoying Li and Liucheng Zhao, the review combines bibliometric analysis with technical, economic, and environmental assessment. Rather than treating recycling as a single chemical operation, the researchers present it as a complete life-cycle system involving collection, sorting, pretreatment, material recovery, environmental management, and the reintegration of recovered products into battery manufacturing.
The review’s bibliometric analysis shows how rapidly this research area has expanded since 2019. China, the United States, and South Korea have emerged as major contributors, reflecting the concentration of battery manufacturing, electric-vehicle production, and energy-storage development in these countries. The focus of research has also evolved. Early studies were strongly oriented toward modifying materials and improving isolated recovery reactions. More recent work increasingly addresses life-cycle management, industrial-scale process integration, carbon emissions, economic feasibility, and the role of recycling within broader energy and manufacturing systems. In other words, the field is moving from the question of whether metals can be recovered to the more difficult question of how they can be recovered sustainably and at commercial scale.
A typical recycling pathway begins with pretreatment. Spent batteries must first be discharged and dismantled safely before components can be separated. Mechanical processes such as crushing, screening, magnetic separation, and gravity separation can concentrate the electrode-rich fraction known as black mass, which contains cathode and anode materials along with conductive additives and binders. Pretreatment is critical because battery packs differ in chemistry, design, state of charge, and degree of degradation. Poorly controlled dismantling can cause short circuits, fires, toxic emissions, or the release of electrolyte compounds. The review also considers echelon, or second-life, utilization, in which batteries that are no longer suitable for electric vehicles may still serve in stationary energy storage before final recycling. Extending battery service life can reduce waste generation, although it also delays material recovery and requires reliable methods for evaluating battery health.
Hydrometallurgy remains one of the most widely studied routes for recovering cathode metals. In this approach, valuable elements are dissolved into an aqueous solution through leaching, often using inorganic acids, organic acids, reducing agents, or other chemical systems. Subsequent purification steps—including solvent extraction, precipitation, ion exchange, and selective crystallization—can separate lithium, cobalt, nickel, and manganese and convert them into compounds suitable for new battery materials. According to the review, hydrometallurgical processes can achieve lithium and cobalt leaching rates above 95 percent under optimized conditions, while also producing relatively high-purity products. Their major weaknesses are the cost and environmental burden of chemical reagents, the generation of acidic or metal-containing wastewater, and the need for complex downstream treatment. A process that recovers metals efficiently but produces large volumes of hazardous liquid waste cannot be considered fully sustainable.
Pyrometallurgy offers a contrasting strategy. Batteries or concentrated black mass are treated at high temperatures, allowing organic components to burn and selected metals to form an alloy or slag. The method is robust, tolerant of mixed feedstocks, and suitable for large-scale continuous operation. It can also simplify pretreatment because some contaminants are destroyed or removed during heating. However, the high temperatures required make pyrometallurgy extremely energy-intensive. Lithium may be lost through volatilization or become trapped in slag, reducing overall resource recovery. The process can also generate substantial greenhouse-gas emissions, particularly when fossil-derived energy is used, and may produce gaseous pollutants that require sophisticated control systems. The researchers therefore describe pyrometallurgy as operationally attractive but environmentally demanding, especially as the battery industry seeks lower-carbon manufacturing and recycling.
Bioleaching represents a greener but slower alternative. Instead of relying primarily on strong chemical reagents, microorganisms or their metabolic products are used to dissolve metals from battery materials. Certain bacteria and fungi can produce organic acids, inorganic acids, or other compounds that promote metal solubilization. Because the process can operate under relatively mild conditions and potentially generate less hazardous waste, bioleaching has drawn attention as an environmentally compatible technology. Its drawbacks are equally clear: metal extraction may take much longer than conventional leaching, microbial activity is sensitive to temperature, pH, nutrient supply, and toxic battery constituents, and maintaining a stable biological system at industrial scale is difficult. These limitations currently restrict bioleaching’s ability to compete with faster chemical routes, although advances in microbial engineering and process control could improve its prospects.
The review identifies direct regeneration as one of the most promising directions for next-generation recycling. Conventional hydrometallurgy and pyrometallurgy generally break cathode materials down into individual elements or salts before those elements are used to manufacture new cathodes. Direct regeneration seeks to preserve and repair the crystal structure of the cathode itself, potentially shortening the process and retaining more of the material’s embedded value. Hydrothermal treatment, relithiation, thermal repair, and electrochemical methods may restore lithium content, reduce structural defects, and recover the performance of degraded cathode powders without fully separating every metal. If successfully scaled, this approach could reduce reagent consumption, energy use, and processing steps. Its central challenge is feedstock variability: cathodes with different chemistries, aging histories, impurities, and compositions cannot always be regenerated through the same recipe.
Emerging solvents could further reshape the recycling landscape. Ionic liquids and deep eutectic solvents have attracted interest because their chemical properties can be tuned for selective dissolution and metal separation. They may enable leaching under milder conditions, reduce volatility, and improve the separation of chemically similar elements. However, their cost, viscosity, recyclability, toxicity profiles, and long-term stability must be assessed before they can be considered truly green alternatives. The researchers emphasize that no single route currently balances recovery efficiency, cost, energy demand, waste generation, and product quality perfectly. A future industrial system is therefore more likely to combine technologies—for example, mechanical pretreatment with selective hydrometallurgy, direct regeneration for suitable cathode streams, and specialized treatment for residues—rather than rely on one universal process.
The study concludes that sustainable battery recycling will require more than laboratory breakthroughs. Digital battery passports could record chemistry, manufacturing history, usage patterns, repair events, and remaining capacity, allowing batteries to be directed toward reuse, echelon applications, or recycling with greater precision. Life-cycle carbon tracking could help manufacturers and regulators compare competing recovery routes using consistent environmental data. Stronger standards for collection, transport, dismantling, worker safety, wastewater management, and recycled-content requirements will also be essential. As electric mobility expands, the success of the battery economy may depend on whether industry can transform end-of-life packs into dependable sources of new materials. The review’s central message is clear: the next phase of lithium-ion battery recycling must be integrated, low-carbon, digitally managed, and designed from the beginning as a closed loop from “end of life” to “new life.”
Subject of Research: Resource recovery and recycling technologies for spent lithium-ion battery cathode materials
Article Title: A systematic review of valuable resource recovery from spent lithium-ion battery cathodes: Technologies, challenges, and future trends
News Publication Date: 29-Jul-2026
Web References: https://doi.org/10.26599/MRSE.2026.9520029
References: Qin, J., Li, S., Zhao, L., et al. “A systematic review of valuable resource recovery from spent lithium-ion battery cathodes: Technologies, challenges, and future trends.” Materials Reports: Solidwaste and Ecomaterials. DOI: 10.26599/MRSE.2026.9520029
Image Credits: Materials Reports: Solidwaste and Ecomaterials, Tsinghua University Press
Keywords: spent lithium-ion batteries, battery recycling, cathode materials, hydrometallurgy, pyrometallurgy, bioleaching, direct regeneration, lithium recovery, cobalt recovery, nickel recovery, circular economy, green technology
