A team of researchers at Korea Advanced Institute of Science and Technology (KAIST) has recently created high-rate, ultra-stable lithium-sulfur batteries (LSBs) by employing hierarchically porous titanium nitride (h-TiN) as a host material for sulfur. It achieved high-rate performance and excellent cycle stability for LSBs.
The control of massive amounts of energy is needed for use in smart grid systems and electric vehicles. To that end, there had been an increasing demand for the development of next-generation secondary batteries. Theoretically, LSBs possess energy density around seven times higher than existing lithium-ion batteries (LIBs). Further, their cost of production can be reduced drastically as sulfur can be obtained at a very low price.
However, there are some issues limiting the commercialization of LSBs including poor electric conductivity of sulfur, sluggish conversion reactions, and dissolution of several active materials during operation. These issues tend to lower the rate capability and cycle stability of the batteries.
To overcome these limitations, Professor Jinwoo Lee from Chemical and Biomolecular Engineering Department and his research team produced a well-built hierarchical macro- or meso-porous titanium nitride as a sulfur host. According to the researchers, TiN not only has good electrical conductivity but also excellent chemical affinity for sulfur. In addition, the macropore or mesopore structures have synergistic effect that enable high-stable accommodation of large quantities of sulfur and facilitates penetration of electrolytes.
Although polar inorganic materials were earlier reported to have high affinity for sulfur, they could not control the porous architecture optimal for sulfur host. The new work tackled such challenges by creating a synthetic path to manage the porous architecture of inorganic materials in an easy manner, which resulted into achieving both cycle stability and high rate capabilities.
Some challenges still impede in commercializing LSBs as new-generation batteries and therefore further research is required to solve these problems, Prof. Lee said.
The study, appeared as cover article in recent issue of journal Advanced Materials, was led by Won-Gwang Lim, a PhD candidate in collaboration with POSTECH’s Jeong Woo Han.