2D carbon selenide offers route to competitive sodium-ion batteries

<p class="p1"><span class="s1">Researchers at TU Delft propose using 2D carbon selenide as a sodium-ion battery anode, offering a theoretical capacity of 589 mAh/g with minimal volume expansion. Computational studies confirmed the material's structural and thermal stability, as well as tunable electrochemical properties, making it a promising candidate for large-scale, renewable-linked energy storage.</span></p><p>A group of researchers at the <a href="https://www.pv-magazine.com/2026/01/26/tu-delft-unveils-liquid-solar-module-encapsulation-tech/" rel="noopener" target="_blank">Delft University of Technology</a> (TU Delft) in the Netherlands has proposed to use <span class="title-text">2D carbon selenide (β-CSe) as an anode material in sodium-ion batteries (SIBs) in an effort to improve device performance and safety. </span></p>
<p>&#8220;At the material level, β-CSe offers a higher theoretical capacity than conventional graphite anodes and some of the lowest ion diffusion barriers reported for any 2D material, which could mean faster charging,&#8221; the research's lead author, Talha Zafer, told <strong>pv magazine</strong>. &#8220;Its tiny volume change during cycling &#8211; 3.2% vs. 300% for silicon anodes &#8211; is a major advantage for longevity and safety. Sodium-ion batteries will likely not beat lithium-ion on energy density per kilogram, but they have clear advantages in cost, safety, and resource sustainability which makes them ideal for stationary storage linked to renewables, which is where the technologys impact could be greatest. It is also worth noting that sodium-ion cells can be safely discharged to 0 V for transport and storage, which is a practical safety advantage that lithium-ion cells do not offer.&#8221;</p>
<p>&#8220;Our β-CSe material's combination of high capacity, low volume expansion, and ultrafast ion transport, which makes it a strong candidate for grid storage applications where durability and cost matter usually,&#8221; he went on to say. &#8220;The fast charge-discharge capability we predict could also help balance the intermittent nature of solar and wind power. In practical terms, if these properties hold up experimentally, this type of material could contribute to making large-scale battery storage more affordable and scalable, as you may know  its one of the key bottlenecks for wider renewables deployment.&#8221;</p>
<div>&#8220;Our study is computational, so we are predicting the fundamental potential of this material rather than reporting device-level results,&#8221; he also said. &#8220;We are confident in our predictions since we validated them with multiple methods and confirmed stability up to 400 K. But real-world performance will ultimately depend on experimental synthesis and testing, including electrode–electrolyte compatibility and long-term cycling. The good news is that similar 2D materials have already been successfully made in the lab, so we believe β-CSe synthesis is within reach. Our results give experimental researchers a strong reason to pursue this material.&#8221;</div>
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<div>In the paper &#8220;<span class="title-text"><a href="https://www.sciencedirect.com/science/article/pii/S0169433226007154#fig2" rel="noopener" target="_blank">Thermodynamic and kinetic properties of 2D carbon selenide for efficient sodium-ion batteries (SIBs)</a>,&#8221; published in <em>Applied Surface Science</em>, Zafer and his colleagues explained they used techniques such as density functional theory (DFT), ab initio molecular dynamics (AIMD), nudged elastic band (NEB) method, and basin-hopping Monte Carlo (BHMC) analysis to determine the structural, dynamical, and thermal stability of the <span class="MathJax_SVG" id="MathJax-Element-11-Frame"></span>CSe monolayer that could be used to build SIB anodes. </span></div>
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<div>The monolayer was modeled using a supercell with a 20 Å vacuum and its thermal stability and electrode reversibility were assessed through AIMD simulations. The fully optimized 2D CSe monolayer was found to exhibit an indirect bandgap of 1.544 eV to 2.1 eV.</div>
<p>The researchers highlighted that their simulations indicate the 2D material’s anisotropic mechanical properties can minimize volume expansion during sodium-ion (Na-ion) intercalation. Sodium atoms bind strongly at hollow sites on the C-side, exhibiting exothermic adsorption and uniform distribution, which helps prevent <a href="https://www.pv-magazine.com/2021/12/09/sodium-battery-research-tackles-formation-of-dendrites/" rel="noopener" target="_blank">dendrite formation</a> and addresses a key challenge in SIB development.</p>
<p>The analysis also showed that the material offers a high theoretical capacity of 589 mAh/g with minimal lattice expansion, outperforming graphite and many 2D anodes. &#8220;Na adsorption transforms the monolayer into a metallic state, ensuring fast electronic conductivity, while extremely low diffusion barriers enable rapid ion mobility,&#8221; Zafer said. &#8220;Mechanical strain and external electric fields allow tunable electronic and adsorption properties, making CSe a highly promising anode for next-generation sodium-ion batteries.&#8221;</p>
<p>&#8220;The material exhibits exceptional structural stability, confirmed by phonon spectra and AIMD simulations at 300 K and 400 K,&#8221; he concluded. &#8220;It features ultralow Na diffusion barriers of 0.019–0.021 eV, far lower than those of typical 2D anodes such as MXenes and phosphorene derivatives.&#8221;</p>
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