Owing to environmental threatens of energy crisis and global warming, high efficient energy conversion and storage systems have been pursued. Of primary subject in the LAB (Laboratory of Advanced Batteries) is to contribute human progress throughout the world via the development of all innovative rechargeable batteries understanding electrochemical characteristics behind the phenomena. The following research goals are identified in the LAB; first, constructing of fascinating battery systems by improvement of present technology and development of new materials, devices and processes; second, unveiling of the fundamental phenomena involved in those electrochemical systems.
High efficient electrochemical energy conversion & storage devices have been required by energy crisis and global warming. Accordingly, batteries including lithium ion batteries having been used for mobile devices have been getting larger and larger for range-extended electric vehicle and huge energy storage system. Therefore, the paradigm of batteries have being changed from small to large powers, is now fueling a drive for the development of more credible and efficient batteries.
1) Lithium ion Batteries (LIBs)
1-1) Electrolytes for LIBs
In the practical view of that the conventional battery system is almost reaching the theoretical limit, the electrolyte is a key factor to tune the performance of LIBs. Besides, during the unexpected dangerous accidents such as explosion and fire of the batteries, highly flammable electrolyte such as carbonate becomes a fuel accelerating those disastrous tragedies. In the LAB, we are devoting to elucidate surface chemistry relating electrolyte in detail by electrochemical and systematic instrumental methods. Non-flammable electrolytes such as Ionic Liquids, alkali salts and addtives are also in our interests.
selected paper :
T. Yim, M.S. Kwon, J. Mun*, K.T. Lee*, Israel Journal of Chemistry, 55 (2015) 586-598.
J. Mun, T. Yim, J.H. Park, J.H. Ryu, S.Y. Lee, Y.G. Kim, S.M. Oh, Sci. Rep., 4 (2014).5802
1-2) Cathode for LIBs
The cathode materials for LIBs have been the focus of intensive research on oxides of transitional metals (Co, Ni, Mn, and V). The major problematic feature encountered in cathode materials is the low energy density from modest amount of lithium ions and poor cyclability from the irreversibly structrual changes, the transition metal dissolution and the electrochemical electrolyte decomposition. In the LAB, many efforts have been focused to solve these challenges, one of which is developoment of new crystalline structure, novel surface coating and metal doping.
Despite many candidates for high energy density LIBs have been suggested, any new types of anodes except graphite are using for practical LIBs owing to the limitation of cyclebility. First of all, we are going to build new anode materials to improve the performance which looks stuttering. Secondly, we are investigating the systematic electrochemical characteristics of beneficial phenomena by using the well-organized analsis methos including EIS, GITT, EVS, XRD, XPS, SEM, TEM, EXAFS, XANES, FT-IR, Raman and DEMS.
1-3) Anode for LIBs
selected paper :
J. Mun, Y.S. Jung, T. Yim, H.Y. Lee, H.-J. Kim, Y.G. Kim, S.M. Oh, J. Power Sources, 194 (2009) 1068-1074.
J. Mun, T. Yim, S. Jurng, J.-H. Park, S.-Y. Lee, J.H. Ryu, Y.G. Kim, S.M. Oh, Electrochem. Commun., 13 (2011) 1256-1259.
2) Aqueous Rechargeable Batteries
Building batteries is a very special technique which increases the cost and hinders the affordability for batteries because of necessity of elimination of water in Batteries. In the LAB, we are going to use aqueous electrolyte instead of the conventional organic electrolytes. If the Aqueous Batteries can be built, the they are very affordable even for the developing country as well as for the ESS and EV thanks to that water electrolyte is very cheap. Therefore, in the LAB, we are going to make a totally new system using water electrolyte for better world.
3) Non-lithium ion Batteries
The scarcity of lithium resources and high costs make the supply of large amounts of lithium required for large scale power sources unaffordable. In order to overcome these challenges from a fundamental technological standpoint, the lithium ions in the electrode materials of LIBs have to be replaced with other suitable and cheaper alkali ions. Unlike lithium, sodium, which is the most basic alkali element, comprises 1.08% of the ocean water and is the sixth most abundant resource on Earth. Therefore, extensive investigations have been conducted on sodium ion batteries (SIBs). Although Na and Li atoms both have a single electron in the valence shell, their electrochemical and crystallographic characteristics are quite different because of the different equilibrium potentials (Na/Na+ = -2.714 and Li/Li+ = -3.045 V vs. NHE) and ionic sizes (116 for Na+ and 90 pm for Li+). Therefore, conducting detailed investigations on SIBs is essential to qualify them as substitutes for LIBs, in order to resolve the present challenges related to the cost and depletion of lithium resources.
selected paper :
J. Lee, K. Chung, H. Jung, H. Kim, J. Mun*, W. Choi Electrochim. Acta 200 (2016) 21-28.
4) Redox Flow Batteries
If you can find the liquid type electrochemically active species, you can consider redox flow batteries (RFBs). Among several types of ESS (Energy Storage System), redox flow batteries (RFBs) have been considered the prospect applications because they can offer large amount energy easily by using large reservoir of the electrolyte. However, the performance of RFB should be improved in the respect of energy density compared with LIB and Ni-MH Batteries. In the LAB, we are studying the high energy density RFB having organic electrolyte to expand the voltage window .
selected paper :
J. Mun, M.-J. Lee, J.-W. Park, D.-J. Oh, D.-Y. Lee, S.-G. Doo, Elecchem. Solid-State Lett., 15 (2012) A80-A82.
H.-s. Kim, S. Jurng, S. Sim, T. Yoon, J. Mun, J.H. Ryu, S.M. Oh, Electrochem. Commun., 58 (2015) 25-28.