Synthesis and Development of CoCrFeNi High-Entropy Alloy from Recycled Battery Scrap and Primary Metals.

With the relentless growth of the global market for electric vehicles and lithiumion batteries, their role in climate protection and the decarbonisation of transport and energy has become crucial, especially when it comes to their end-of-life management. Various European and international regulations and directives, which set increasingly high material recovery rates, highlight the urgency of developing effective recycling solutions. Metals recovered from battery recycling, such as cobalt, nickel, and iron, can be used as raw materials in the production of advanced materials. Among the possible applications, the synthesis of highentropy alloys is an area of particular interest, offering a unique combination of mechanical, thermal and chemical properties. The purpose of this thesis is to synthesise the CoCrFeNi and CoCrFeNi2 alloy and investigate the effectiveness of the pyrometallurgy method for recovering base metals from end-of-life battery material. After contextualising battery handling in the context of recycling and introducing high-entropy alloys, the related experiments are described. The results are then presented and discussed. In this limited experimental investigation, the results highlight the complexity and critical issues associated with the treatment and recovery of material from spent batteries, confirming the need for further studies to make battery recycling a more efficient and sustainable process. Furthermore, the properties observed, although derived from the single experimental cases of the CoCrFeNi and CoCrFeNi2 alloys, give a glimpse of the potential of this class of materials, confirming the technological interest in further studies on high-entropy alloys. These results suggest that an integrated approach combining the recycling of spent batteries with the production of advanced materials could represent a promising strategy for both promoting the circular economy and developing new high-performance applications.