Sodium-Ion Capacitor Technologies and Performance

Sodium-ion capacitors (SICs) represent a hybrid energy storage technology that bridges the high energy density of batteries with the rapid charge–discharge capability and long cycle life of supercapacitors. By employing sodium rather than lithium, these devices benefit from the earth’s abundant sodium resources and lower material costs, addressing sustainability and large-scale deployment. Central to their performance are electrode architectures that balance capacity and kinetics: negative electrodes typically rely on pseudocapacitive materials or intercalation hosts, while positive electrodes exploit high-surface-area carbons for electrical double-layer capacitance. Advances in nanostructuring, doping and composite design have yielded electrodes with enhanced ion transport pathways, enlarged interlayer spacing and robust structural integrity under repeated cycling. Meanwhile, electrolyte engineering—ranging from optimised organic solvents to ionic liquids—has extended the electrochemical stability window and improved ionic conductivity. Recent efforts focus on tuning electrode–electrolyte interfaces and mitigating the inherent trade-offs between energy density, power density and operational lifetime. As a result, state-of-the-art SICs now achieve energy densities approaching those of sodium-ion batteries at power densities characteristic of supercapacitors, positioning them as promising candidates for grid balancing, electric mobility and portable electronics.

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Sodium-Ion Capacitor Technologies and Performance publication trend

The graph below shows the total number of articles in sodium-ion capacitor technologies and performance across all publications each year (not limited to Nature Index journals).

Technical terms

Sodium-ion capacitor: A hybrid electrochemical device that utilises sodium ions to combine battery-type energy density with supercapacitor-type power density and cycling stability.

Pseudocapacitance: A charge storage mechanism involving fast, reversible surface redox reactions rather than solely electrostatic ion adsorption.

Intercalation: The reversible insertion of sodium ions into the crystal lattice of an electrode material during charge and discharge processes.

Mesoporosity: The presence of pores in the 2–50 nm range within an electrode material, facilitating rapid ion transport and high accessible surface area.

References

1. Hierarchically Structured Nb2O5 Microflowers with Enhanced Capacity and Fast-Charging Capability for Flexible Planar Sodium Ion Micro-Supercapacitors. Nano-Micro Letters (2024).
2. 3D Porous Oxygen‐Doped and Nitrogen‐Doped Graphitic Carbons Derived from Metal Azolate Frameworks as Cathode and Anode Materials for High‐Performance Dual‐Carbon Sodium‐Ion Hybrid Capacitors. Advanced Science (2023).
3. Boosted Surface‐Redox Pseudocapacitance in 2D Mesoporous TiN for High‐Power Sodium‐Ion Capacitors. Small Structures (2023).
4. Electrolyte Technologies for High Performance Sodium-Ion Capacitors. Frontiers in Chemistry (2020).