New method enables ultra-fast charging of lithium batteries

Electric vehicles are developing rapidly, but the slow charging speed of lithium-ion batteries is still a problem. In order to make batteries with fast charging capabilities, researchers have long been committed to enhancing electrolyte mass transfer and charge transfer in electrodes, especially the former.

(Image source: ACS)

According to foreign media reports, researchers from the Japan Advanced Institute of Science and Technology (JAIST) have demonstrated a new method that uses binder materials to promote the insertion of lithium ions into active materials to achieve fast charging. Binder materials can improve the diffusion of desolvated lithium ions within the solid electrolyte interface (SEI) and anode materials, thereby achieving high conductivity, low impedance and good stability.

Researchers Noriyoshi Matsumi and Professor Rajashekar Badam said: "The current strategy is to use bioderived lithium borate polymers as aqueous polyelectrolyte binders to enhance charge transfer within the electrode, such as graphite anodes showing fast charging capabilities."

Professor Matsumi said: "The binder material includes highly dissociable lithium borate, which can promote the diffusion of lithium ions in the negative electrode matrix. In addition, this binder can form organic boron SEI. Compared with ordinary batteries, this type of binder can SEI shows very low interface resistance."

The role of boron compounds (such as four-coordinated boron and boron-rich SEI in binders) is to help desolubilize lithium ions by reducing the activation energy of lithium ions dissolving from the solvent sheath at the SEI. Furthermore, in the case of high diffusion and low impedance, the overpotential associated with charge transfer at the interface can be reduced. Dr. Anusha Pradhan from JAIST said: “This is one of the important factors in achieving ultra-fast charging.

Generally, lithium plating occurs on graphite electrodes when the charging speed exceeds the speed of lithium intercalation. This is an undesirable process that results in shortened battery life and affects fast charging capabilities. This research improves the diffusion of ions on the SEI and within the electrode, limiting the concentration polarization of lithium ions, so no electroplating layer appears on the graphite.

In this study, the researchers not only proposed new strategies to achieve extremely high-rate rechargeable batteries and reduce interfacial resistance, but also used a biopolymer derived from caffeic acid. Caffeic acid is a plant-based organic compound that is a sustainable source of material. Using bioresources in batteries helps reduce carbon dioxide emissions. Professor Matsumi said: "In future research, this binder can also be combined with high-rate charging active materials to achieve a synergistic effect and further improve performance."

As battery performance is further studied, users can look forward to greener ways of using energy, especially in the transportation sector. Professor Matsumi said: “With high-rate rechargeable battery technology, people can enjoy electric vehicles and convenient mobile devices. Because renewable resources are used, product availability can be maintained for a longer period of time, regardless of the availability of fossil resources and social conditions. "