Understanding dual-ion storage benefits and challenges of all carbon-fiber-plate candidate electrodes in sodium-ion structural batteries

Structural batteries (SBs) are gaining attention for their potential to improve lightweight, radiation-free designs in defense and transportation. Applications include aircraft, unmanned aerial-vehicles (UAVs), electric-vehicles (EVs), public transit, and vertical-take-off-and-landing (VTOL) platforms, enhancing performance and maximizing spatial efficiency by integrating energy storage into structural components. The current study focuses on the electrochemical properties of commercial carbon-fiber-plate (CFP) candidate electrode-based sodium-ion structural batteries (NISBs), specifically investigating their dual-ion storage mechanism. This research provides an in-depth understanding of the electrochemical behavior of CFP|Na cells across two voltage ranges: 0.01–3.0 V and 3.0–5.0 V, paving the way for the development of CFP|CFP functional devices. Data from CFP|Na cells operating in the 3.0–5.0 V range demonstrated stable cycling performance; however, it also revealed a less-than-optimal Coulombic efficiency (CE) due to the complex dual-ion storage kinetics. CFP|Na cells perform well within the 0.01–3.0 V range, showing favorable kinetics during both sodiation and de-sodiation. It's worth noting that these cells require at least 30 discharge-charge cycles to achieve their peak performance. The CFP|CFP symmetric full devices, fabricated using cycled CFP electrodes, demonstrated promising capabilities with good capacity and discharge potential. However, discrepancies in performance metrics need to be addressed for better NISB development. This research evaluates the practical applications of CFP-based NISB systems in relevant fields.