#South Korea #Gwangju #Chonnam National #Sodium Metal Batteries #Electrolyte Technology

Groundbreaking Electrolyte Development at Chonnam National University

In a remarkable achievement, a research team from Chonnam National University in South Korea has pioneered a new non-flammable and more robust electrolyte for sodium metal batteries (SMBs). This innovation comes at a crucial time when the demand for alternative energy storage solutions grows, largely due to the environmental concerns surrounding traditional lithium-ion batteries.

Sodium metal batteries are starting to attract attention as a viable option due to the lower cost and abundant access to sodium. However, despite this promise, the practical implementation of these batteries faces significant challenges, especially regarding safety and stability. One of the major hurdles is the high reactivity of sodium metal, which can lead to dendrite formation and unwanted side reactions. These issues not only shorten battery life but can also result in severe failures under high-temperature conditions often encountered during energy storage applications.

In response to these challenges, Professor Chan-Jin Park and his team have introduced a polymerizable deep eutectic solvent (PDES) electrolyte. This revolutionary electrolyte not only enhances safety by being non-flammable and resistant to leakage, but it also boasts high cycle stability and ionic conductivity, making it an ideal candidate for future sodium metal batteries.

Composition and Mechanism

The PDES electrolyte is composed of sodium perchlorate (NaClO4), N-isopropylacrylamide (NIPAM), and succinonitrile (SN). When these components are blended, they form a homogeneous liquid stabilized by intermolecular interactions such as hydrogen bonding and ion-dipole interactions. This mixture is known as a deep eutectic solvent (DES) which, while possessing favorable properties like non-flammability and thermal stability, is often subject to leakage.

To overcome the leakage issue, the researchers employed an in-situ polymerization technique, transforming the liquid mixture into a robust solid matrix—effectively creating the PDES electrolyte. This polymer structure enhances Na-ion transport and solves many of the issues faced by conventional SMB electrolytes.

Key components include NaClO4, which provides the Na-ion source beneficial for salt dissociation due to weak coordination between the perchlorate anion and sodium ions. The NIPAM component facilitates Na-ion dissociation, contributing to a robust polymer matrix. In contrast, SN grants added plasticity and assists further in Na-ion dissociation. By working together, these properties create an environment conducive to effective Na-ion transport.

The optimized composition of the PDES electrolyte is noted for establishing impressive results, achieving ionic conductivity of 1.39 mS cm–1 at ambient temperatures, alongside a high transference number of 0.58.

Performance and Applications

When tested in full cells, this advanced PDES electrolyte showcased its ability to form a stable electrode-electrolyte interface during cycling. This development effectively suppressed parasitic reactions and encouraged regular Na metal growth. The full cell with the optimized electrolyte achieved an initial discharge capacity of 110.2 mAh g-1 at a rate of 0.1 C, maintaining nearly 99% coulombic efficiency. Furthermore, it exhibited remarkable cycling stability, retaining 90.4% of its capacity over 1,000 cycles at a rate of 2 C.

In a notable demonstration of its durability, researchers fabricated a pouch cell with this electrolyte that could continue to power an LED even when folded or cut, highlighting the safety and mechanical robustness of the PDES electrolyte.

Professor Park expressed great enthusiasm for the implications of their work. He stated that their electrolyte design for SMBs heralds a new era of safer, more affordable, and sustainable rechargeable battery technologies. These innovations could potentially enable the utilization of sodium metal batteries in renewable energy storage systems and other low-cost applications, creating pathways for supporting grid-level energy storage and backup power systems.

The research findings were published online in the prestigious journal Energy Storage Materials and signal exciting advancements in the field of battery technology.

Reference:

• - Title of original paper: Noncovalent interaction-regulated polymerizable deep eutectic solvent electrolyte for sodium metal batteries
• - Journal: Energy Storage Materials
• - DOI: 10.1016/j.ensm.2026.105430