Application of borides in battery cathode materials

 

The structure of TiB2 and MgB2 is similar to a typical hexagonal crystal system, showing a layered structure, and the Ti-B between the layers is an ionic bond. Therefore, TiB2 has high electrical conductivity, far exceeding that of activated carbon and porous graphitic carbon. Li et al. synthesized titanium boride (TiB2) nanoparticles by a magnesium metal hydrolysis-assisted method as a positive sulfur-fixing carrier for Li-S batteries. The excellent electrical conductivity of TiB2 provides an effective way for charge transfer at the TiB2/S interface. It is confirmed by DFT calculation and XPS spectroscopy that a large number of Ti atoms on the surface of TiB2 are highly coordinatively unsaturated, have abundant dangling bonds, and have a strong interaction with elemental sulfur. After TiB2 contacts with sulfur, self-sulfidation occurs, and the surface acts as an anchoring surface to interact with lithium polysulfide in an electrochemical reaction, resulting in dual chemical S-S and S-Li bonds.

 

Metal borides have unique physical and chemical properties. As a positive support material for Li-S batteries, the solid sulfur/catalysis mechanism needs to be clearly analyzed, so as to improve metal borides in all directions under the condition of high sulfur loading in poor electrolytes. Therefore, a metal boride cathode support material with high sulfur loading, low liquid sulfur ratio, high specific energy, and long cycle has been developed, thereby promoting the practical application of Li-S batteries.