How environmentally friendly are batteries with no rare or critical materials?

Conference poster, 2022

Rechargeable batteries are increasingly used in a number of applications, such as consumer electronics, electric vehicles, and stationary energy storage. An increased use in the latter two applications is envisioned to reduce greenhouse gas emissions.However, the dominant rechargeable battery technology – the lithium-ion battery (LIB) – impacts the environment in several ways throughout its life cycle. In addition, LIBs require critical and/or geochemically scarce materials, such as lithium, natural graphite, and sometimes nickel and cobalt. One promising next generation battery (NGB) is the sodium-ion battery (SIB). While other NGBs can provide higher energy densities, the SIB technology holds great promise from a resource point of view, since it can be made to contain mostly low-cost, abundant and readily available elements, such as sodium and iron. In addition, the manufacturing processes and equipment developed for LIBs can in principle be re-used, enabling convenient scale-up of production. We here assess the life-cycle impacts of a specific SIB with a low content of scarce metals using prospective life cycle assessment (LCA). The SIB is assumed to be a mature technology produced at large scale and this we accomplish by using data from a small-scale producer and scale these up using available large-scale factory data for LIB production. We use a functional unit of 1 kWh of installed battery cell storage capacity and focus on climate and mineral resource impacts, since those have been highlighted in several publications and guidance documents as particularly important to address in LCAs of batteries. Different shares of renewables are considered in energy supply scenarios, along with scenarios for specific energy density developments. The impacts are compared to those of large-scale produced LIBs and to another NGB – the lithium-sulfur battery. To investigate mineral resource impacts of the different technologies in depth, we include two resource impact assessment methods, the crustal scarcity indicator and the surplus ore potential. The aims of the study are (i) to assess the prospective life cycle impacts of the SIB technology in order to reveal whether it is preferable to other battery technologies from an environmental and resource point of view, and (ii) to understand the environmental profile of the SIB in order to identify hotspots.