Researchers at the German Federal Institute for Materials Research and Testing (BAM) have presented a new concept for anode materials in sodium-ion batteries. This concept is intended to increase efficiency and storage capacity at the same time.
Initial efficiency only at 18 percent
In conventional anodes, electrolyte molecules decompose and penetrate the pores of the hard carbon anode during the first charging process, known as “formation.” These molecules occupy “empty spaces” intended for sodium ion storage. Without targeted material modification, the initial efficiency of the material is only 18 percent.
Efficiency increased to 82 percent
The newly developed core-shell design has a double structure. A sponge-like hard carbon interior stores sodium ions, and a thin outer layer acts as a filter that allows the desired sodium ions to pass through while keeping disruptive electrolyte molecules out. According to BAM, the material is based on inexpensive, environmentally friendly activated carbon. This is said to increase the initial efficiency to 82 percent. The research team believes that further improvements are possible because the separation of ion formation and energy storage allows for new material combinations.
Further development of the anode material
Future development of the anode material will take place at the Berlin Battery Lab, a research consortium comprising BAM, the Helmholtz Center Berlin, and Humboldt University. The “DialySorb” and “NMR-Batt” projects, in which the material was developed, are funded by the German Federal Ministry of Research, Technology and Space.
