From black mass to "grey mass" – mechanical recycling of sulfide solid-state batteries

Sulfide solid-state batteries (SSBs) are a promising next generation energy storage technology due to their high ionic conductivity and theoretical energy densities. However, compared to conventional lithium-ion batteries (LIBs), the recycling of sulfide SSBs remains poorly understood. Here, a novel mechanical recycling process, consisting of two comminution steps and a subsequent material separation, has been developed to recycle sulfide SSB cells. Optimized initial comminution was essential to open the battery and produce a processable bulk material with favorable particle sizes of cell and housing material. A second comminution step was used to selectively comminute the electrode and separator material, concentrating the valuable materials, in particular the cathode active material (CAM) and sulfide SE, into a fine fraction, the so-called “grey mass”, with recovery yields up to 86 wt%. The results for single-layer pouch cells were confirmed by transferring the experiments to multi-layer pouch and industrial pouch cells. By considering the subsequent processing, a holistic process chain was developed, taking into account the possible direct recycling of the recovered SE and the CAM. This innovative recycling process for is highly efficient, and produces valuable recycling products, contributing to the advancement of a sustainable circular economy in battery technology.