Tin Interlayer: A Revolutionary Solution to Prevent Short-Circuits in Lithium-ion Batteries

Lithium-ion batteries are celebrated for their high energy density, rapid recharge capabilities, and ability to withstand numerous charge-discharge cycles. However, one of the most significant challenges faced by these batteries is their vulnerability to short-circuits. When a short-circuit occurs, it can lead to a sudden loss of voltage or an abrupt, high-current discharge, which may cause the battery to fail. In severe cases, short-circuits can even cause the battery to overheat, ignite, or explode.

Understanding Short-Circuits in Lithium-ion Batteries

A short-circuit in a lithium-ion battery typically occurs when there is an unintended connection between the cell's two electrodes. This connection can lead to catastrophic failure, especially if it results in a rapid discharge of energy. One of the primary causes of short-circuits in these batteries is the formation of dendrites—microscopic, tree-like structures that grow on the electrodes. If these dendrites expand enough to reach the opposing electrode, they can cause a short-circuit.

The Role of Dendrites in Battery Failure

Dendrites are crystalline structures that form during the charging process, particularly in conditions where lithium ions are unevenly deposited on the electrode surfaces. Over time, these dendrites grow and can eventually pierce the separator that keeps the electrodes apart, leading to a short-circuit. This not only poses a safety risk but also limits the efficiency and longevity of the battery.

Breakthrough Research from the University of Alberta

Researchers from the University of Alberta (UAlberta), in collaboration with the Canadian Light Source (CLS) at the University of Saskatchewan (USask), have developed an innovative approach to mitigate the formation of dendrites in solid-state lithium-ion batteries. Their research, published in the ACS Applied Materials and Interfaces journal, introduces a tin-saturated interlayer between the electrode and the electrolyte. This tin layer disperses lithium during deposition, creating a smoother surface that is less conducive to dendrite formation.

How the Tin Interlayer Works

The tin interlayer operates by altering the deposition dynamics of lithium on the electrode. During the charging process, lithium tends to deposit in a manner that can lead to rough, uneven surfaces, which are prone to dendrite growth. The tin-saturated layer, however, promotes a more uniform deposition of lithium, resulting in a smooth, dendrite-resistant surface. This significantly reduces the likelihood of short-circuits and enhances the overall stability of the battery.

Enhanced Performance with Tin-rich Structures

The UAlberta researchers found that batteries equipped with this tin-rich interlayer could handle much higher currents and endure more charge-discharge cycles compared to standard cells. This improvement not only extends the battery’s life but also makes it safer for high-performance applications, such as in electric vehicles or large-scale energy storage systems.

Significance of the HXMA Beamline in the Research

Assistant Professor Lingzi Sang from UAlberta’s Faculty of Science (Chemistry) emphasized the crucial role of the HXMA beamline at CLS in their research. The beamline allowed the team to observe and understand the structural changes on the lithium surface in real-time, at a material level, within an active battery. This deepened their understanding of how the tin interlayer suppresses dendrite formation and mitigates short-circuit risks.

Earlier Discoveries and the Future of Battery Safety

This isn’t the first time the UAlberta team has explored the potential of tin as a protective layer. In an earlier study, they demonstrated that a tin coating could also prevent dendrite formation in liquid-electrolyte-based lithium-ion batteries. These cumulative findings point to a broader applicability of the tin interlayer technology across different types of lithium-ion batteries.

Industrial Implications and Future Directions

According to Professor Sang, the development of this tin interlayer technique has significant potential for industrial application. The next step for the research team is to develop a cost-effective, scalable method for integrating this protective layer into the manufacturing process of lithium-ion batteries. If successful, this could lead to a new generation of safer, more reliable batteries with widespread commercial use.