“Low cost/low end” birnessite–like manganese oxide recovered from Amazon mining tailings as high–performance conversion–type anode materials for lithium (Li)–ion batteries

The present study explores the sustainable recovery of manganese from mining waste for use in lithium (Li)-ion batteries. Manganese, classified as a critical raw material by the European Union in 2023, is crucial in energy storage devices due to its electrochemical properties. Manganese was extracted as a potassium manganate solution from Amazon mining tailings and converted into nanostructured manganese oxides. Specifically, hydrogen peroxide, ethanol, and manganese sulfate were used as reductants so as to determine their effectiveness in creating manganese oxide suitable for battery application. The synthesized materials were characterized using XRD, Raman spectroscopy, thermal analysis (TG-DTA), ESEM, and TEM. The results confirmed the recovery method was highly efficient, green and cost-effective. Manganese recovery rates reached up to 99%, demonstrating the method's efficacy. Additionally, it was found that synthesis conditions and choice of reducing agent significantly influenced chemical and physical properties of resulting materials. These factors particularly affected the crystallinity, particle morphology, and electrochemical performance of the synthesized manganese oxides. Manganese oxide synthesized using manganese sulfate showed the best electrochemical performance when tested as a conversion-type anode material in Li-ion batteries. It delivered a specific capacity of around 400 mAh/g after 100 cycles, outperforming the commercial graphite capacity under similar conditions. This greater performance was linked to its unique morphology, which combined features of the other samples, and its moderate crystallinity, which aided efficient charge transport. This research provides a promising pathway for the sustainable recycling of manganese, aligning with the “Critical Raw Materials Act”. The results indicate that Mn-rich mining waste can be successfully converted into high-performance battery materials, providing both environmental and economic advantages.