Inorganic Photoluminescent Microparticles as Identifiers for the Sorting of Lithium-Ion Battery Cathodes

The growing demand for lithium-ion batteries in the European Union contributes to critical raw material scarcity. This challenge can be addressed by establishing a circular economy, making use of highly efficient and economical recycling processes. The efficiency of these processes depends on high-purity material streams and thus on the availability of battery data during recycling. While common identifiers could carry this information, they are not suitable for every use case. The present study proposes the use of photoluminescent (PL) microparticles as identifiers for the efficient sorting of battery cathodes. These particles are implemented in the electrodes and can be identified by their unique fluorescence emission signals. This study demonstrates the feasibility of using PL microparticles in the cathode environment and focuses on their practical application in a pre-industrial pilot sorting facility. The relationship between particle concentration and measurable emission signal is ascertained, and the influence of the PL particles on the electrochemical performance is examined. Highly efficient sorting using three different PL microparticles is demonstrated on a pilot-scale sorting plant. Finally, an overview of the wide variety of possible identifier codes is provided, which is key to exploiting the potential of this technology.