The sustainable advancement of green energy storage technologies hinges on the efficient utilisation of readily available and cost-effective materials. In this context, here, I delve into the eco-friendly conversion of natural minerals and biomass into functional materials tailored for metal-ion energy storage applications. Particular emphasis is placed on the mechanochemical, thermal, and molten salt modification techniques developed at E²MC to nanostructuring minerals such as molybdenum disulfide, ilmenite, and natural graphite, as well as biomass. These processes result in the creation of nanostructured electrode materials with enhanced electrochemical performances for use in Li-ion and/or Na-ion batteries. The phase transformations that occur during these modification processes are explored and their consequential impact on key factors such as metal-ion storage capacity, diffusion coefficients, and surface pseudocapacitive behaviors are discussed. Furthermore, I would underscore the economic benefits stemming from the utilisation of abundant and economical materials in the development of highly efficient battery systems.