Korean researchers have succeeded in improving the performance of lithium-sulfur secondary batteries that are regarded as an althernative to conventional lithium-ion batteries.
The Korea Advanced Institute of Science and Technology (KAIST) announced on Jan. 27 that its research team led by Prof. Lee Jin-woo of the Department of Chemical and Biomolecular Engineering has developed a sulfur material by synthesizing inorganic materials that have different pore sizes.
The team synthesized titanium nitride with two different types and sizes of pores by simultaneously inducing multidimensional phase separation and used it as a sulfur material to develop a lithium-sulfur secondary battery with excellent lifetime stability and speed.
Lee said, "Lithium-sulfur secondary batteries still have a lot of problems to be worked on," emphasizing the need for further development. However, he added, "From this research, we have acquired an unrivaled technology for the development of cathode materials with stable lifetime."
As new technologies such as electric vehicles and smart grid require large-capacity energy control, the need for the development of next-generation secondary batteries has been increasing.
Theoretically, the lithium-sulfur secondary battery exhibits an energy density about seven times higher than that of a conventional lithium ion battery. In addition, the low price of sulfur is expected to dramatically reduce the unit cost of battery production.
However, there are limitations for its commercialization because the anode and cathode of the lithium-sulfur secondary battery have a lot of problems. In particular, problems of low electric conductivity of sulfur in the cathode, and sulfur leakage from the electrode during charging and discharging are yet to be solved.
In an effort to solve such problems, the team developed a layered porous structure of titanium nitride-based sulfur material with macro pores over 50 nanometers and mesopores below 50 nanometers. The team confirmed that synergistic effects of the structure help the battery maintain high life stability and speed while stably containing a large amount of sulfur.