Environmental assessment of a new generation battery: The magnesium-sulfur system

TL;DR

This study evaluates the environmental impacts of a hypothetical magnesium-sulfur battery using life cycle assessment, highlighting current limitations and future potential to outperform lithium-ion batteries if design improvements are achieved.

Contribution

It provides the first detailed environmental assessment of MgS batteries and explores their future improvement potential compared to lithium-ion systems.

Findings

Initial MgS prototype has higher environmental impacts than LIB.

Optimized MgS could outperform LIB in environmental and performance metrics.

MgS batteries have significant future potential if design challenges are overcome.

Abstract

As environmental concerns mostly drive the electrification of our economy and the corresponding increase in demand for battery storage systems, information about the potential environmental impacts of the different battery systems is required. However, this kind of information is scarce for emerging post-lithium systems such as the magnesium-sulfur (MgS) battery. Therefore, we use life cycle assessment following a cradle-to-gate perspective to quantify the cumulative energy demand and potential environmental impacts per Wh of the storage capacity of a hypothetical MgS battery (46 Wh/kg). Furthermore, we also estimate global warming potential (0.33 kg CO2 eq/Wh) , fossil depletion potential (0.09 kg oil eq / Wh), ozone depletion potential (2.5E-08 kg CFC-11/Wh) and metal depletion potential (0.044 kg Fe eq/Wh), associated with the MgS battery production. The battery is modelled based on an existing prototype MgS pouch cell and hypothetically optimised according to the current state of the art in lithium-ion batteries (LIB), exploring future improvement potentials. It turns out that the initial (non-optimised) prototype cell cannot compete with current LIB in terms of energy density or environmental performance, mainly due to the high share of non-active components, decreasing its performance substantially. Therefore, if the assumed evolutions of the MgS cell composition are achieved to overcome current design hurdles and reach a comparable lifespan, efficiency, cost and safety levels to that of existing LIB; then the MgS battery has significant potential to outperform both existing LIB, and lithium-sulfur batteries.