The cathode chemistry at the heart of the study, LiNi0.5Co0.2Mn0.3O2, known throughout the industry as NCM523, is one of the most widely used formulations in modern electric vehicle batteries. Its layered crystal structure packs lithium ions between slabs of nickel, cobalt and manganese oxides, a configuration that stores charge efficiently but also makes recycling complicated. Conventional recycling routes typically rely on strong acids and reducing agents to dissolve the entire cathode, producing a leachate that contains lithium mixed with nickel, cobalt and manganese. Separating those metals from one another demands multiple extraction and precipitation steps, each of which consumes chemicals, energy and money. The Jishou team set out to avoid that bottleneck by asking a different question: rather than forcing every metal into solution, could lithium be selectively extracted while the remaining transition metals are upgraded in place into something valuable?

The answer, according to the new study, is yes, and the key reagent is sodium persulfate, a common industrial oxidizer. Persulfate salts are powerful sources of sulfate radicals, and the researchers harnessed that oxidizing power to attack the cathode lattice in a controlled way. When the spent cathode powder was exposed to a sodium persulfate solution under the right conditions, lithium was leached out of the layered oxide with remarkable efficiency, reaching 97.38 percent under the optimized recipe. Just as important, the process was highly selective: lithium accounted for 79.90 percent of the metal recovered relative to the co-leached nickel, cobalt and manganese, meaning the great majority of the transition metals stayed behind in the solid residue rather than contaminating the lithium stream. That selectivity is precisely what conventional hydrometallurgy struggles to achieve without elaborate separation chemistry.

Getting to those numbers required careful optimization of three variables. The team found that a calcination pretreatment at 420 degrees Celsius was ideal, a temperature low enough to keep the energy budget modest but sufficient to modify the cathode structure in ways that favor lithium extraction. The dosage of sodium persulfate was tuned to 1.0 gram per liter, a concentration that provides enough oxidizing capacity to liberate lithium without driving excessive amounts of nickel, cobalt and manganese into solution. The initial pH was set to a neutral 7.0, an unusually mild condition for battery leaching, which typically operates in strongly acidic media. Running the reaction at neutral pH reduces corrosion risks, simplifies wastewater handling and lowers the overall chemical footprint of the process, all of which matter for any realistic industrial deployment.

What happens to the solid residue left behind after lithium removal is where the study makes its most imaginative leap. In most selective leaching schemes, the delithiated cathode is a byproduct to be dealt with later. Here, the researchers showed that the residue transforms directly, inside the same reaction vessel, into a ternary mixed-phase catalyst composed of nickel oxide, cobalt oxide and manganese dioxide in the form of MnOx phases. The delithiation step itself, driven by the persulfate oxidation, restructures the layered oxide into this new composite without any additional synthesis steps. In effect, the process converts the spent cathode’s residual metal content into a functional photocatalytic material as a built-in consequence of the lithium recovery chemistry, eliminating the need for a separate manufacturing chain.

The catalytic performance of this waste-derived material proved impressive. When tested against methylene blue, a standard model dye used to benchmark water-treatment catalysts, the converted product degraded 98.29 percent of the pollutant in an independent persulfate-activation photocatalytic system. Even in the original one-pot configuration, where lithium leaching and pollutant degradation happen side by side, methylene blue removal reached 91.50 percent. The dual functionality means a single batch of spent cathode powder can yield both a recovered lithium stream and an active catalyst, with the reaction medium doing double duty as a leaching bath and a treatment reactor. For municipal or industrial wastewater operators, the prospect of a catalyst sourced from battery scrap that attacks persistent dyes and organic contaminants is an appealing example of circular economy thinking in practice.

To understand why the catalyst works so well, the team dug into the underlying reaction mechanisms, combining radical-trapping experiments with liquid chromatography tandem mass spectrometry to trace the degradation pathways of the dye. Their analysis pointed to two main engines of destruction. First, light absorbed by the mixed metal oxide catalyst generates photogenerated holes, highly oxidizing entities that can directly attack organic molecules and also drive the formation of secondary reactive species. Second, the multivalent nickel, cobalt and manganese ions in the catalyst cycle between different oxidation states, shuttling electrons to and from the persulfate and dissolved oxygen. These redox cycles promote the generation of singlet oxygen and superoxide radicals, two reactive oxygen species that are efficient at breaking down aromatic dye molecules into smaller fragments, ultimately mineralizing them.

The identification of singlet oxygen as a key player is noteworthy because it distinguishes this system from many advanced oxidation processes that rely predominantly on hydroxyl or sulfate radicals. Singlet oxygen is a more selective oxidant, which can be advantageous in complex water matrices where nonselective radicals are quickly quenched by background constituents such as carbonate or natural organic matter. The combination of photogenerated holes with the cooperative Ni, Co and Mn redox chemistry appears to create a balanced reactive environment in which multiple oxidants operate in parallel, giving the catalyst robustness that single-metal systems often lack. The LC-MS/MS analysis of intermediates provided a molecular-level picture of how methylene blue is dismantled step by step, supporting the mechanistic model rather than relying on inference alone.

The broader context makes the work timely. Studies cited by the authors document the rapid growth of the retired electric vehicle battery stream and the regulatory pressure building around battery recycling worldwide, from business-model analyses of the recycling industry to reviews of global sustainability regulations. Pyrometallurgical routes, which melt batteries at high temperature, lose lithium to slag and demand substantial energy. Hydrometallurgical routes recover more metal but generate acidic waste and struggle with selective separation. Approaches that couple advanced oxidation processes with chemical leaching have emerged as a middle path, and the new study pushes that concept further by making the leaching step itself productive, yielding not just purified lithium but a ready-made catalyst from the same operation.

There are, of course, questions that will need answering before a laboratory one-pot process becomes an industrial flowsheet, including how the method handles real, heterogeneous black mass containing binders, conductive carbon and mixed cathode chemistries, and how the catalyst performs over many reuse cycles. But the numbers reported by the Jishou team, near-complete lithium extraction, strong lithium selectivity, and dye degradation above 98 percent by the waste-derived catalyst, demonstrate that the individual pieces of the concept work. If the approach scales, the humble pile of spent cathode powder awaiting recycling could become a feedstock for two products at once: the lithium that future batteries need, and the catalysts that future water treatment plants will use to keep dye-laden effluent out of rivers. It is a vivid illustration of how rethinking a waste stream, atom by atom, can turn an environmental liability into a pair of assets.

Subject of Research: Selective lithium recovery from spent NCM523 lithium-ion battery cathodes and their in-situ conversion into a persulfate-activating photocatalyst for pollutant degradation

Article Title: A one-pot process for selective lithium recovery and in-situ transformation of NCM523 cathodes into a high-performance photocatalyst

Article References: Hu, Y., Liu, Z., Liu, B., Zou, Q., Li, F., Xiang, Y., & Liu, Y. (2026). A one-pot process for selective lithium recovery and in-situ transformation of NCM523 cathodes into a high-performance photocatalyst. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13821-6

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13821-6

Keywords: lithium-ion battery recycling, NCM523 cathode, selective lithium leaching, sodium persulfate, photocatalysis, methylene blue degradation, singlet oxygen, superoxide radicals, transition metal oxides, advanced oxidation processes, waste-to-resource, circular economy