Sodium-Ion Battery Anode Intercalation Chemistry

The intercalation chemistry of sodium-ion battery anodes centres on the reversible uptake and release of sodium ions within layered host structures, offering a lower-cost and more abundant alternative to lithium-based systems. Unlike lithium, sodium exhibits a larger ionic radius and distinct solvation behaviour, which challenges conventional graphite hosts yet enables unique co-intercalation pathways. Bare sodium ions face a thermodynamic barrier to insertion into graphite, but the co-intercalation of solvated sodium species within graphite galleries can proceed with high reversibility and rapid kinetics. This mechanism induces pronounced expansion and contraction of the interlayer spacing, demanding tailored binder formulations and electrode architectures to manage volume changes. Beyond graphite, disordered carbons, hard carbons and heteroatom-doped carbon networks have been developed to balance capacity, rate performance and cycling stability. These intercalation processes underpin the global drive towards sustainable grid storage and portable power, where optimised electrolytes, nanoscale confinement and innovative anode designs converge to unlock the full potential of sodium-ion chemistry.

Research from Nature Portfolio

Studies have demonstrated that tuning the stability of ternary graphite intercalation compounds through electrolyte composition can adjust the redox potential of sodium-ion anodes by up to 0.38 V, delivering cells with voltages above 3 V and power densities exceeding 3800 W kg−1. By optimising solvent activity and solvent–graphite interactions, these developments have achieved negligible temperature dependence of energy and power densities and capacity retention losses below 0.01% per cycle over thousands of cycles, marking a significant advance for large-scale sodium-ion full cells.

Sodium-Ion Battery Anode Intercalation Chemistry publication trend

The graph below shows the total number of articles in sodium-ion battery anode intercalation chemistry across all publications each year (not limited to Nature Index journals).

Technical terms

Intercalation: The reversible insertion of guest ions into the layered structure of a host material without significant structural collapse.

Co-intercalation: A process in which ions enter the host lattice together with part or all of their solvation shell.

Ternary graphite intercalation compounds (t-GICs): Graphite phases containing both alkali ions and solvent molecules within the interlayer galleries.

Nanoconfinement: Spatial restriction at the nanometre scale within electrode materials that influences ion transport and reaction thermodynamics.

Solid electrolyte interphase (SEI): A passivating layer formed at the electrode–electrolyte interface that regulates ion flux and stabilises surface reactions.

References

1. Unifying electrolyte formulation and electrode nanoconfinement design to enable new ion–solvent cointercalation chemistries. Energy & Environmental Science (2024).
2. In Situ Pore Formation in Graphite Through Solvent Co‐Intercalation: A New Model for The Formation of Ternary Graphite Intercalation Compounds Bridging Batteries and Supercapacitors. Advanced Energy Materials (2023).
3. Mechanical Activation of Graphite for Na‐Ion Battery Anodes: Unexpected Reversible Reaction on Solid Electrolyte Interphase via X‐Ray Analysis. Advanced Science (2024).
4. Tailoring sodium intercalation in graphite for high energy and power sodium ion batteries. Nature Communications (2019).
5. Solvated Ion Intercalation in Graphite: Sodium and Beyond. Frontiers in Chemistry (2020).
6. Strategies for Alleviating Electrode Expansion of Graphite Electrodes in Sodium‐Ion Batteries Followed by In Situ Electrochemical Dilatometry. Energy Technology (2020).
7. Nano Hard Carbon Anodes for Sodium-Ion Batteries. Nanomaterials (2019).
8. S and P Dual-Doped Carbon Nanospheres as Anode Material for High Rate Performance Sodium-Ion Batteries. Applied Sciences (2021).