Sodium-ion capacitors (SICs) bridge the energy-power gap between batteries and supercapacitors, offering sustainable and scalable energy storage solutions. This review provides a 360-degree perspective on SIC technology, covering material choices, presodiation strategies, manufacturing challenges, applications and life cycle assessment to ensure economic, social, and environmental sustainability. The path toward commercial viability and large-scale deployment is critically analyzed.

Abstract

Now that fast action is needed to mitigate the effects of climate change, developing new technologies to reduce the worldwide carbon footprint is critical. Sodium ion capacitors can be a key enabler for widespread transport electrification or massive adoption of renewable technologies. However, a years-long journey needs to be made from the first proof-of-concept report to a degree of maturity for technology transfer to the market. To shorten this path, this work gathers all the stakeholders involved in the technical development of the sodium ion capacitor technology, covering the whole value chain from academics (TRL 1–3) and research centers (TRL3–5) to companies and end-users (TRL 6–9). A 360-degree perspective is given on how to focus the research and technology development of sodium ion capacitors, or related electrochemical energy storage technologies, from understanding underlying operation mechanisms to setting up end-user specifications and industrial requirements for materials and processes. This is done not only in terms of performance metrics, but mainly considering relevant practical parameters, i. e., processability, scalability, and cost, leading up to the final sustainability evaluation of the whole of the technology by Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) analysis, which is of utmost importance for society and policymakers.