Scheduled for Thursday 25th September: Advancing Sodium-Ion Storage with Alloy-Type Anodes and Ether-Based Electrolytes

You are invited to a SafeREnergy Seminar

Date: Thursday, 25th September 2025
Time: 2:00pm – 3:00pm (AEST)

Join here: Zoom

Advancing Sodium-Ion Storage with Alloy-Type Anodes and Ether-Based Electrolytes

Lithium-ion batteries (LIBs) have proven to be promising energy storage systems for both transportation and stationary applications. Significant advancements in LIB production have been achieved over the last few decades. However, the limited availability of critical elements such as Li, Ni, and Co, together with geopolitical factors, significantly hampers their large-scale deployment. Sodium-ion batteries (SIBs) present a promising alternative to LIBs, as both exhibit similar electrochemical behavior. Since the beginning of commercialization, graphite has been regarded as the state-of-the-art anode for LIBs. A major limitation of SIBs, however, is that graphite cannot store significant amounts of Na with conventional carbonate electrolytes, due to the thermodynamic instability of binary graphitic intercalation compounds (b-GICs). The sodium storage capacity of graphite can be improved by replacing carbonate-based electrolytes with ether-based ones, although their overall performance may still be insufficient for producing high-energy-density batteries. Furthermore, several carbon materials, including hard carbon with unique morphologies, are being investigated as anodes for SIBs. However, the overall capacity of carbon-based anodes remains insufficient for achieving high-energy-density batteries.

As alternatives, many nanostructured materials have been proposed as anode candidates. Among them, Sn is particularly attractive due to its high capacity (Na₁₅Sn₄, 847 mAh g^-1) and a suitable redox activity range (0.15-0.40 V vs. Na⁺/Na). However, it undergoes a large volume expansion (~ 420%) in the fully sodiated state (Na_3.75Sn), leading to battery failure. Similarly, other alloy-type electrodes (e.g., Bi, Sb, Si) that offer high capacities and fast Na⁺ diffusion kinetics are also being intensively investigated for Na⁺ storage. Alloying Sn with other p-block elements, such as Sb (660 mAh g^-1, Na₃Sb), represents an additional strategy to mitigate volume-change-related issues. Recently, we reported a new alloy-based material, GaSb confined in Sn (GaSb@Sn), supported by a mixture of multiwalled carbon nanotubes and reduced graphene oxide, for efficient Na⁺ storage in SIBs. The purpose of incorporating Ga was to investigate whether liquid Ga could stabilize the structure by mitigating the large volume changes of Sn (Na_3.75Sn) and Sb (Na₃Sb), owing to its self-healing nature, while also contributing to Na-ion storage through NaGa4 formation. The GaSb@Sn/C-based electrode delivered a high specific capacity of 560 mAh g^-1 (second cycle) at 50 mA g^-1 and demonstrated excellent cycle stability at 1000 mA g^-1, retaining 89% of its capacity after 1200 cycles. Operando XRD was employed to investigate the Na⁺ storage mechanism. The GaSb@Sn/C electrode exhibited a 33% expansion at the electrode level during sodium insertion, significantly lower than the theoretically predicted expansion of Sn (420%), as confirmed by operando electrochemical dilatometry (ECD). This self-healing nature, combined with reduced volume changes, resulted in long cycle life across different current densities.

Conventional Li-ion and Na-ion batteries use carbonate-based electrolytes, which are highly flammable and prone to catching fire in the event of a short circuit or overcharge. These safety concerns can be mitigated by developing all-solid-state batteries (ASSBs) that employ solid electrolytes (SEs) instead of liquid carbonate-based electrolytes. In ASSBs, all cell components-anodes, cathodes, and electrolytes-are in the solid state. The electrode materials (both anodes and cathodes) employed in LIBs and SIBs are typically used in ASSBs as well. So far, research on ASSLIBs has largely focused on the development of SEs and cathodes, while the development of anode materials has been scarcely explored and remains at an early stage. Herein, an Sn-graphite composite electrode is employed as the negative electrode for ASSBs.

Presented by Dr T Palaniselvam, Assistant Professor, Department of Chemistry, Indian Institute of Technology Madras, India

Palaniselvam is a materials chemist whose research focuses on developing functional materials for energy storage and conversion devices. He received his Ph.D. in 2014 from the CSIR-National Chemical Laboratory, India. During his Ph.D., he developed and explored various graphene-based electrocatalysts for the oxygen reduction reaction in polymer electrolyte membrane fuel cells. Following his Ph.D., he carried out postdoctoral research at the Ulsan National Institute of Science and Technology, South Korea, and at King Abdullah University of Science and Technology, Saudi Arabia.

In 2017, he was awarded the Alexander von Humboldt Postdoctoral Fellowship and moved to Friedrich Schiller University Jena, Germany, to work in the laboratory of Prof. Philipp Adelhelm. Subsequently, he continued his research in the same group at Humboldt University of Berlin, Germany, until May 2022. During this period, he developed various Sn-based anode materials for sodium-ion batteries and investigated the sodium-ion storage mechanism using different in situ techniques.

In June 2022, he joined the Department of Chemistry at IIT Madras as an Assistant Professor.