Electrochemical variability of natural mineral mixtures as electrode materials in Li-ion batteries

Natural mineral systems can be effectively used to make battery material supply chains more secure and sustainable. However, the impact of their multi-mineral electrochemistry must be considered for effective deployment. Mine tailings are shown as a potential sustainable natural mineral source. A simplified ternary system of pyrite, quartz and muscovite was examined for its trends in electrochemical performance. Mixing of minerals is shown to adversely affect charge transfer impedance (R _ct) and diffusion coefficient (D _Li⁺ ) values post-cycling; R _ct values are 10 times greater for mixtures than pure phase minerals, and D _Li⁺ values are an order of magnitude lower than pure phase minerals. Within mixtures, the component of capacity from pyrite decays more rapidly than in a pure mineral phase. A comparison with two mine tailings reveals the inclusion of lesser amounts of pyrite in a majority silicate mixture to boost electrochemical performance, while the opposite leads to reduced performance. The results convey that a clear link between mineral composition and expected electrochemical performance is required to fully realise the benefits of mixed natural mineral sources for sustainable battery electrodes.