A sustainable δ-MnO₂ derived from Amazon rainforest Mn-ore tailings for applications in lithium-ion batteries

The transition to net-zero emissions by 2050 necessitates the development of sustainable and efficient energy storage systems to complement the rise in renewable energy generation. Lithium-ion batteries (LiBs) are pivotal in this energy transformation, yet challenges remain in developing sustainable, high-performance materials. Manganese oxides (MnOx) are promising candidates for LiBs anodes due to their abundance and high theoretical capacity. However, the commercial synthesis of MnOx materials is resource-intensive, and the mining processes generate large amounts of environmentally hazardous tailings. In this study, we propose a novel method to recover manganese from mining tailings in the Brazilian Amazon and synthesize delta-MnO2 as a high-capacity conversion anode material for LIBs. Using a green recovery method involving KOH and H2O2, we extracted potassium manganate (K2MnO4) from the tailings with a recovery efficiency of 90.3 %,and synthesized delta-MnO2. The prepared material showed promising electrochemical properties, demonstrating its potential as a sustainable alternative to commercially available manganese oxides. This process not only offers a way to mitigate the environmental risks posed by manganese mining tailings but also provides an economically viable solution for producing high-performance battery materials. The developed methodology can be applied to other manganesebearing residues and low-grade ores, contributing to the growing demand for battery-grade manganese in a sustainable and circular manner.