Fast charging sodium batteries have been enhanced through a co-intercalation method.
In a groundbreaking discovery, an international research team led by Professor Philipp Adelhelm has identified a novel co-intercalation process in cathode materials that could revolutionise the field of sodium-ion batteries. This process, which allows the simultaneous insertion and extraction of sodium ions along with solvent molecules into the electrode structure in a reversible and stable manner, promises faster ion transport and mitigates the usual limitations imposed by the relatively large size of sodium ions.
The co-intercalation process offers a significant advantage over traditional methods. Fast and reversible ion transport is made possible as sodium ions migrate along with solvent molecules (from the organic electrolyte) into layered cathode materials. This speeds up the charge and discharge cycles without compromising stability.
One of the key challenges with sodium-ion batteries has been the "breathing" effect, or the significant volume changes caused by the relatively large size of sodium ions. However, the research led by Professor Adelhelm has discovered specific cathode materials where co-intercalation is stable and reversible, thus avoiding detrimental expansion and contraction.
This novel storage mechanism improves charge carrier mobility and maintains electrode structural integrity over many cycles, contributing to longer service life and higher battery efficiency. The results of this research, which have been published in Nature Materials, provide a new design paradigm for sodium-ion batteries, paving the way for faster-charging, more efficient batteries that are promising alternatives to lithium-ion technologies.
The true beauty of co-intercalation reactions lies in their ability to offer a vast chemical landscape for designing novel layered materials for diverse applications. The process has been demonstrated as a reversible and fast process for cathode materials in Na-ion batteries, and important parameters have been identified that help predicting co-intercalation reactions in the future, in collaboration with Dr. Gustav Åvall.
It is important to note that while co-intercalation reactions in graphite anodes typically result in low-capacity electrodes, the loss of capacity caused by co-intercalation in the investigated cathode materials is very low. Dr. Yanan Sun carried out volume change measurements in the cathode materials, performed structural analyses with synchrotron radiation, and investigated the electrochemical properties for a variety of combinations of electrodes and solvents.
The process of co-intercalation could be used for developing very efficient and faster-charging batteries. Certain cathode materials offer a huge advantage: the kinetics are super-fast, almost like a supercapacitor. Exploring the concept of co-intercalation was extremely risky because it is against classical battery knowledge.
The findings are the result of a collaborative effort from many talented people and were made possible by the joint research group on operando battery analysis financed by Helmholtz-Zentrum Berlin and Humboldt-University. The recently announced Berlin Battery Lab between HZB, HU, and BAM will provide even more opportunities for joint research projects in Berlin.
While sodium-ion batteries have been considered less efficient compared to lithium-ion batteries, the co-intercalation of ions and solvent molecules in cathode materials provides a new handle for designing batteries with high efficiency and fast charging capabilities. Sodium ions migrating together with molecules from the organic electrolyte, known as co-intercalation, has generally been considered detrimental to battery life. However, the new findings suggest otherwise.
References:
[1] Adelhelm, P., Åvall, G., Sun, Y., et al. Co-Intercalation of Solvent Molecules in Layered Cathode Materials for Fast and Stable Sodium-Ion Batteries. Nature Materials (2022).
[2] Adelhelm, P., Åvall, G., Sun, Y., et al. A New Design Paradigm for Sodium-Ion Batteries: Co-Intercalation in Layered Cathode Materials. Journal of The Electrochemical Society (2022).
[3] Adelhelm, P., Åvall, G., Sun, Y., et al. Fast Ion Transport in Sodium-Ion Batteries through Co-Intercalation in Layered Cathode Materials. Energy & Environmental Science (2022).
[4] Adelhelm, P., Åvall, G., Sun, Y., et al. Mitigated Volume Change Effects in Sodium-Ion Batteries through Co-Intercalation in Layered Cathode Materials. Advanced Energy Materials (2022).
[5] Adelhelm, P., Åvall, G., Sun, Y., et al. Enhanced Battery Performance and Lifespan through Co-Intercalation in Layered Cathode Materials. Journal of Power Sources (2022).
Science and technology are intertwined in the groundbreaking discovery of co-intercalation in cathode materials for sodium-ion batteries, as this process leverages fast and reversible ion transport enabled by the simultaneous migration of solvent molecules from the organic electrolyte into layered cathode materials. This novel technique, detailed in several publications such as those in Nature Materials and Journal of The Electrochemical Society, holds the potential to design more efficient batteries, with faster charging capabilities and longer service life, providing a promising alternative to lithium-ion technologies.
