Sodium-ion batteries offer promising technology
The development of new battery technologies is moving fast in the quest for the next generation of sustainable energy storage – which should preferably have a long lifetime, have a high energy density and be easy to produce.
The research team at Chalmers chose to look at sodium-ion batteries, which contain sodium – a very common substance found in common sodium chloride – instead of lithium. In a new study, they have carried out a so-called life cycle assessment of the batteries, where they have examined their total environmental and resource impact during raw material extraction and manufacturing.
"The materials we use in the batteries of the future will be important in order to be able to switch to renewable energy and a fossil-free vehicle fleet," says Rickard Arvidsson, Associate Professor of Environmental Systems Analysis at Chalmers.
"We came to the conclusion that sodium-ion batteries are much better than lithium-ion batteries in terms of impact on mineral resource scarcity, and equivalent in terms of climate impact. Depending on which scenario you look at, they end up at between 60 and just over 100 kilogrammes of carbon dioxide equivalents per kilowatt hour theoretical electricity storage capacity, which is lower than previously reported for this type of sodium-ion battery. It's clearly a promising technology," says Rickard Arvidsson.
The study is a prospective life cycle assessment of two different sodium-ion battery cells where the environmental and resource impact is calculated from cradle to gate, i.e. from raw material extraction to the manufacture of a battery cell. The functional unit of the study is 1 kWh theoretical electricity storage capacity at the cell level.
Both types of battery cells are mainly based on abundant raw materials. The anode is made up of hard carbon from either bio-based lignin or fossil raw materials, and the cathode is made up of so-called "Prussian white" (consisting of sodium, iron, carbon and nitrogen). The electrolyte contains a sodium salt. The production is modelled to correspond to a future, large-scale production. For example, the actual production of the battery cell is based on today's large-scale production of lithium-ion batteries in gigafactories. The article Prospective life cycle assessment of sodium-ion batteries made from abundant elements has been published in the Journal of Industrial Ecology.
