Prospective screening life cycle assessment of a sodium-ion hybrid supercapacitor

Report, 2024

Hybrid supercapacitors combine batteries' energy density with capacitors' power density. They can extend the lifetime of an electrical vehicle battery by reducing the number and depth of the charge/discharge cycles and by enhancing the battery’s power capacity. Traditionally, hybrid supercapacitors contain lithium, a geochemically scarce metal. To mitigate a future lithium shortage, measures could be taken to substitute lithium with more abundant materials. One option is sodium-ion hybrid supercapacitors.

In this report, we assess the climate and mineral resource scarcity impacts of manufacturing a sodium hybrid supercapacitor by means of life cycle assessment. The goal is to identify hotspots to aid researchers, developers, and potential manufacturers in making environmentally benign design choices.

The considered sodium-ion hybrid supercapacitor is not yet produced at large scale but only in laboratories. To address this, we scale up the production process to an industrial scale using frameworks available in the literature. Results show that the activated carbon electrode is responsible for most of the environmental impact due to the use of nitric acid in processing the activated carbon. If nitric acid could be replaced, recycled, or reduced, this would lower the environmental impact considerably. Additionally, we provide guidance on how to scale up the mass of the sodium-ion hybrid supercapacitor to meet the requirement of a vehicle. This upscaling also means that the results can be used in screening assessments by vehicle developers interested in how the sodium-ion hybrid supercapacitor could influence the environmental impact of their vehicle.