Innovative recycling of critical materials through thermal recovery for sustainable and reliable lithium-ion batteries

In recent decades, the demand for lithium-ion batteries (LIBs) and their applications has increased dramatically, while the required resources are limited, leading to a more than doubled demand-to-supply ratio globally in 2030. While additional efforts in mining and resource extraction could solve some supply issues, they also bring with them high pollution, safety concerns, equity issues, supply chain dependencies and global issues, as well as inclusion and social responsibility issues worldwide.

Therefore, it is of great importance for the LIB industry to rely less on mining and sourcing and to shift the ecosystem and business environment towards a circular economy. One of the most innovative, sustainable and profitable methods is the implementation and adoption of highly efficient and environmentally friendly recycling processes for lithium-ion batteries. Among the raw materials in lithium-ion batteries, graphite - natural or synthetic - is the most commonly used material for LIB anodes. [1] 

Natural graphite is classified as a highly critical raw material in the EU [2], while synthetic graphite is derived from coke [3] - a carbon precursor produced from coal or petroleum. Therefore, cost-effective, efficient and high-yield recycling and reuse strategies for graphite are essential milestones on the road to sustainability and resource conservation, which are strategically mentioned in the new EU regulations requiring the use of recycled battery materials from 2030.

In this study, we report on a novel and highly efficient thermal recycling process for the recovery of high-quality graphite from LIBs for LIBs. After a detailed material characterization of the recovered materials, we performed extensive electrochemical characterizations in half cells and graphite||NMC811 full cells and compared the results with the data for half cells and full cells using commercial graphite. In half cells, the recycled graphite shows considerably high reversible specific capacities (e.g. 350 mAh g^-1 at C/20) with very stable cycling.

More importantly, the pouch cells using recycled graphite||NMC811 show very good cycling stability at C/3 over 500 cycles with 80% capacity retention. Finally, the comparison with the original graphite full cells shows a very comparable performance and highlights the great potential of recycled and reused graphite as an important step towards clearly sustainable and reliable LIBs towards a circular economy.

[1,2] Department of Cell R&D Engineering, Siro Silk Road Clean Energy Solutions, Gebze, Kocaeli 41400, Türkiye
[3] Niocycle Technologies, Gebze, Kocaeli 41400, Türkiye