Recycling metal resources from various spent batteries to prepare electrode materials for energy storage: A critical review

The number of spent batteries is enormous, causing tremendous environmental pressure and waste of resources. It is promising to recycle metal resources from spent batteries and prepare fresh electrode materials. This review systematically summarizes the current technologies (pyrometallurgy, hydrometallurgy, and direct recovery) of recovering metal resources from spent batteries and the strategies of transforming recovered metal resources into electrode materials for various energy storage devices (lithium-ion batteries, supercapacitors, lead-acid batteries, Zn-air batteries, etc.). Herein, bibliometrics is used to summarize the research of the last 20 years in this field and future challenges are put forward. Moreover, it also predicts that the direct use of active materials from spent batteries and compounding them with low-cost commercial materials could be a potential alternative to synthesizing electrode materials. We expect this work could lay a foundation for the industrial application of recycling metal resources in spent batteries to prepare electrode materials.