From trash to treasure: new method efficiently regenerates spent lithium cobalt oxide batteries
Tsinghua University Press
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Schematic illustration of the regeneration process for heavily degraded lithium cobalt oxide (LCO) cathodes. Through ball milling, the spinel-phase structured spent LCO (SLCO) is transformed into an amorphous intermediate (rLCO), facilitating lithium replenishment and structural restoration. Subsequent treatment with LiOH enables the formation of regenerated LCO (RLCO) with restored layered architecture and electrochemical performance.
view moreCredit: Energy Materials and Devices, Tsinghua University Press
Lithium-ion batteries are essential for powering electronics and electric vehicles, yet their limited lifespan—typically 5 to 8 years—leads to massive volumes of hazardous waste. Current recycling technologies such as pyrometallurgy and hydrometallurgy are energy-intensive, environmentally harmful, and inefficient, especially when dealing with severely degraded cathodes. These materials often suffer from structural collapse, lithium depletion, and the formation of surface spinel phases like Co₃O₄, which hinder regeneration. While direct recycling offers a cleaner alternative, it struggles with uneven lithium diffusion and high energy barriers. These challenges highlight the urgent need for innovative, low-impact methods that can effectively restore the functionality of spent LIB cathodes.、
Published in March 2025, in Energy Materials and Devices, a collaborative study (DOI: 10.26599/EMD.2025.9370059) unveiled a ball milling-assisted technique to revitalize aged LiCoO₂ (LCO) cathodes. By transforming degraded crystal structures into amorphous intermediates, followed by sintering at high temperatures, the researchers successfully reconstructed the layered architecture and regained battery-grade performance. The regenerated cathodes demonstrated a capacity of 179.10 mAh·g⁻¹ at 0.5 C, matching that of new commercial materials. The method offers compelling advantages over conventional recycling pathways in terms of efficiency, cost, and environmental footprint—marking a significant step toward sustainable battery reuse.
At the heart of this study lies a structural transformation strategy driven by ball milling. The process converts the rigid and defect-prone spinel phase (Co₃O₄), commonly formed on degraded LCO cathodes, into a homogeneous amorphous phase. This intermediate not only alleviates internal stress but also facilitates uniform lithium reintegration during subsequent high-temperature sintering. The regenerated LCO (RLCO) cathodes achieved a high discharge capacity of 179.10 mAh·g⁻¹ at 0.5 C, closely matching commercial standards. Performance metrics were promising: 91.7% initial Coulombic efficiency and 88% capacity retention after 100 cycles. Finite element modeling confirmed superior lithium diffusion within the amorphous phase, compared to conventional repair techniques. Economically, the method reduces recycling costs by approximately 25% compared to hydrometallurgy, eliminates the generation of toxic wastewater, and offers a projected profit of $1,503 per kilogram of recovered material. Advanced characterization techniques—including HAADF-STEM, XRD, and XPS—verified the full restoration of the layered crystal structure and the removal of Co²⁺-related defects. The results address longstanding barriers in direct cathode regeneration and lay the foundation for extending this method to other widely used cathode chemistries, such as nickel-manganese-cobalt (NMC) and lithium iron phosphate (LFP).
“This work reframes structural degradation as an opportunity,” said Dr. Guangmin Zhou, co-corresponding author of the study. “The amorphous intermediate acts as a ‘repair highway’ for lithium, offering a generalizable strategy for regenerating other cathode materials like NMC or LFP.” Independent experts have highlighted the method’s potential for large-scale deployment, citing its ability to cut raw material dependency and reduce electronic waste. The study’s balance of scientific rigor and practical feasibility makes it an important reference for the future of battery recycling.
This regeneration technique holds strong promise for sustainable battery technology and circular economy efforts. By enabling efficient, large-scale recycling of degraded LCO cathodes, the method could significantly reduce dependence on virgin cobalt and lithium—critical resources with constrained and geopolitically sensitive supply chains. Its cost-effectiveness and operational simplicity position it well for industrial adoption, with potential integration into existing battery manufacturing workflows. Furthermore, it aligns with stringent environmental regulations such as the EU Battery Regulation, offering a low-carbon, waste-free alternative to legacy recycling systems. Beyond LCO, the underlying principles of amorphous-phase engineering and structural restoration could be applied to other chemistries, supporting broader innovation in next-generation energy storage solutions.
This work was supported by a project of the Tsinghua Shenzhen International Graduate School-Shenzhen Pengrui Young Faculty Program of Shenzhen Pengrui Foundation (Grant No. SZPR2023007), Natural Science Foundation of Sichuan Province (Grant No. 2025ZNSFSC0449), and Shenzhen Science and Technology Program (Grant No. RCBS20231211090637065).
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Journal
Energy Materials and Devices
Article Title
Reconstructing Lithium Replenishment Channel by Amorphous Structure to Facilitate the Regeneration of Spent LiCoO2 Cathodes
Spray drying tech used in instant coffee applied to high-capacity battery production
Achieved world-leading 98% active material content in electrode
National Research Council of Science & Technology
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(Front row, left) Senior Researcher Jihee Yoon from KIMS and (Front row, right) Senior Researcher Insung Hwang from KERI successfully manufactured dry electrodes for high-capacity secondary batteries using the spray drying technique.
view moreCredit: Korea Electrotechnology Research Institute
The Korea Electrotechnology Research Institute (KERI) and the Korea Institute of Materials Science (KIMS) have jointly developed the 'spray drying technology-based high-performance dry electrode manufacturing technology' for the realization of high-capacity secondary batteries.
Secondary battery electrodes are made by mixing 'active materials' that store electrical energy, 'conductive additives' that help the flow of electricity, and 'binders' which act as a kind of adhesive. There are two methods for mixing these materials: the 'wet process', which uses solvents, and the 'dry process', which mixes solid powders without solvents. The dry process is considered more environmentally friendly than the wet process and has gained significant attention as a technology that can increase the energy density of secondary batteries. However, until now, there have been many limitations in achieving a uniform mixture of active materials, conductive additives, and binders in dry process.
To solve this problem, KERI and KIMS applied the 'spray drying' technology, which has already been proven for mass production in the food and pharmaceutical industries, to the dry process. First, the researchers at KIMS mixed the active materials and conductive additives in a liquid slurry form and then sprayed them into a high-temperature chamber made of glass tubes. The principle is that the solvent evaporates instantly due to the high temperature inside the chamber, leaving only a uniformly mixed composite powder of active materials and conductive additives. This method is the same process used in the mass production of instant stick coffee, where coffee concentrate is sprayed and hot air is applied to produce solid powder.
The composite powder of active materials and conductive additives made using the spray drying technique was transformed into high-capacity electrodes by the researchers at KERI, who possess extensive know-how and expertise in ‘dry-electrode processes’. The researchers mixed the composite of active materials and conductive additives with binders, then carried out a process called 'fibrillation,' in which the binders are stretched into threads using specially designed equipment. Through this delicate process, the 'active materials-conductive additives-binders' were better woven together as a structure and could be precisely combined. Finally, the researchers went through a 'calendering' process, where the combined active materials, conductive additives, and binders were made into a thin film with uniform density, ultimately producing electrodes for batteries.
KERI and KIMS believe that this achievement will realize high capacity in secondary batteries. Thanks to this, it becomes possible to achieve optimal mixing between the internal materials of the secondary battery, reducing the amount of conductive additives compared to before, and instead filling that space with active materials, which are directly related to battery capacity.
The researchers who conducted the joint study drastically reduced the amount of conductive additives from the 2-5% range reported in existing dry electrode-related literature to as low as 0.1%, through numerous experiments. They also successfully achieved a world-leading level of 98% for the content of active materials. In addition, the dry electrodes manufactured using this method achieved an areal capacity of approximately 7 mAh/cm², which is double that of commercial electrodes (2-4 mAh/cm²). The related research results were recognized for their high technological expertise and recently published in the world-renowned journal *Chemical Engineering Journal* (IF 13.3 / Top 3%).
Senior Researcher Insung Hwang from KERI's Next Generation Battery Research Center explained the significance of the research results, stating that the optimal combination of electrode materials can enhance energy density and performance, and that this technology has great potential as it can be applied to next-generation battery fields such as solid-state batteries and lithium-sulfur batteries. Senior Researcher Jihee Yoon from KIMS' Convergence and Composite Materials Research Division stated, "Through follow-up research, we plan to reduce process costs, improve mass production capabilities, and increase technology maturity, with the goal of eventually transferring the technology to companies."
Meanwhile, both KERI and KIMS are government-funded research institutions under the NST(National Research Council of Science & Technology) of the Ministry of Science and ICT. This research, which can be considered a model case of collaborative research between government-funded research institutions, was jointly conducted through NST's Creative Convergence Research Project (CAP21044-210) and MOTIE's Machinery and Equipment Industry Technology Development Project (RS-2024-00507321).
Journal
Chemical Engineering Journal
Article Title
A breakthrough in dry electrode technology for high-energy-density lithium-ion batteries with spray-dried SWCNT/NCM Composites
ng from KERI is manufacturing dry electrodes for secondary batteries using a process called "calendering," which involves turning composite powders into film form.
The 'spray drying equipment' that significantly improves the mixing of internal materials for dry electrodes in secondary batteries.
Senior Researcher Insung Hwang from KERI (left) and Senior Researcher Jihee Yoon from KIMS are using spray drying equipment to manufacture composite powders of active materials and conductive additives.
Credit
Korea Electrotechnology Research Institute
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