Battery

Importance of secondary battery

•  • Because of the increase of using mobile device and the growth of electric vehicle market, portable energy storage system has been required.
•  • Secondary batteries which can store electric energy as chemical energy are one of the promising candidates of energy storage system because of their high energy density.

Recent issues of battery research

 • Increasing the energy density and stability of battery and increasing ion conductivity of solid electrolyte and lowering contact resistance between solid-electrolyte and electrode.

|  Current research in FNL

1. Increasing the energy density and stability of battery

 • We are trying to develop anode material of lithium metal battery which made of conductive MOF (Metal-Organic Framework). Lithium-ion intercalation can change the electrical conductivity of the conductive MOF and it can be used for preventing the formation of lithium dendrite.

 • Generally, MOF have high porosity and they are lithiophilic. But because they are electrically insulating, we are trying to combine MOF and conducting polymer together so that can storage the lithium metal inside MOF.

2. Solid ion conductors and weakly coordinating anions

 •  In solid ion conductors, anion is bonded to a bulk rigid structure which prevents the anion movement and limits the anion conduction and ion polarization.  This eventually enhances the cation conduction and cation transference number.

 • Anions, which are weakly coordinating with cations, are known as weakly coordinating anions and its charger is delocalized over the entire surface. Weak coordination between cation-anion inhibits the ion pair formation and enhances the cation mobility. Moreover bulk structure of the anion can lower its mobility and limits the anion conduction, thus improves the cation transference number and overall conductivity.

•  • Borate anions, owing to the lower electronegativity of boron, are tends to delocalized their charge. Hence they become a good candidate for WCAs. With a much low ion dissociation energy ( 539 KJ/mol), they have low tendency to form ion pars or aggregations

3. ASEI (Artificial Solid Electrolyte Interface)

 • Other : Pore size larger then 1.5nm,no functional group help Li conduction

 • Our plan: pore size around 0.3nm ,functional group(SO₃H COOH)

4. Distillation

• Other:Membrane wettability and ion selectivity cannot have both. Pore size>1.5nm

• Our plan: one membrane outside hydrophobic inside hydrophilic and the pore size much more smaller.(0.3nm around)

Device Application

Necessity of Graphene Photonics

 • Recently, the LiDAR industry has received attention and been growing, but the mechanical structure LiDAR currently used has a limitation in price efficiency and computer processing speed. Various studies are being conducted to solve this problem.
 • The need for high-performance LiDAR is being raised in the mobile robot and autonomous vehicle industry.

The issue of graphene Photonics

 • LiDAR, which is currently used as the mainstream, has a problem that PD's position must be changed for reception after LD transmission because PD and LD's position are not co-axial.
 • This problem can be solved if the PD and LD positions are made into co-axial structures.

| Current research topics and research objectives

 • In this study, graphene PD was generated in LD of near-infrared area based on wave guide to produce on/off optics in which LD/PD coexists in an integral structure.
 • To this end, a stamp-type dry transfer method for transferring graphene to an accurate position is important, and a simulation research is actively conducted to verify the performance of optics by making it a graphene device.

Fig 1 . Scheme summarizing the principles of the graphene PD structure and the phonic switch tuning the work-function of graphene

Fig 2 . The transfer process scheme using the ongoing polymeric material stamp

Fig 3 . Top-gate Field-effect Transistors (Gr-TGFETs) Structure Using Graphene

Electrocatalyst

Necessity of the electrochemical catalysts

 • We currently live in a carbon society that utilizes carbon-based energy systems. Carbon society is not adequately responding to environmental problems as well as global population growth and increased energy demand, requiring a different energy system. The electrochemical reaction is a reaction that stores and supplies energy through the conversion of energy or produces high value-added chemicals and plays an important role in future energy systems.
 • The electrochemical catalyst determines the rate, efficiency, and selectivity of these electrochemical reactions and is therefore the most important element in energy conversion technology. Therefore, research and development of electrochemical catalysts are essential to achieving a carbon-neutral society.

Recent issue in electrochemical catalyst research

 • Currently, electrochemical catalysts are mainly manufactured based on precious metals, especially platinum catalysts.
 • However, the high price of platinum catalysts is an obstacle to the universal commercialization of electrochemical catalysts.
 • To solve this problem, research is being actively conducted to significantly reduce the amount of platinum used or to replace platinum with an inexpensive transition metal.

 • Electrochemical catalysts play an important role in fuel cell driving and hydrogen production.
 • Hydrogen is an energy efficient, eco-friendly and stable raw material. Depending on the production method, it is classified into Gray hydrogen, Blue hydrogen, and Green hydrogen, which can reduce carbon dioxide emissions through water electrolysis reaction.
 • Water electrolysis is an electrochemical reaction that decomposes water using electrical energy, and the hydrogen generation reaction (HER) at the anode and oxygen generation reaction (OER) at the cathode, so that surplus power can be converted to hydrogen energy and stored.
 • In order to achieve high activity, it is necessary to lower the overpotential of each reaction and bring the initiation potential close to the equilibrium potential.
 • A fuel cell is a device required for a reaction that converts hydrogen energy into electrical energy, and a hydrogen oxidation reaction (HOR) occurs at the anode and an oxygen reduction reaction (ORR) occurs at the cathode.
 • For high activity, the half wave potential and limit current density of ORR must be increased.
 • Many previous studies have been reported on catalysts with high activity for each reaction, but their durability is limited or their application to actual applications (water electrolysis cells, fuel cells).
 • Therefore, it is essential to develop a catalyst material with a new structure that is different from the previous one.

|  Current research topics and research objectives

 • This laboratory manufactures various 2D materials effective in hydrogen generation reactions and reports the results of research to evaluate their characteristics, and is conducting research on water electrolysis and fuel cells through the development of various catalyst materials.
 • Through the catalyst design with a new structure different from the previous one, a catalyst with high activity, durability, and low manufacturing cost is developed, and research is being conducted to receive the catalyst and apply it to fuel cells.
 • Various oxide-based catalysts using metal-organic frameworks (MOF) as precursors and monoatomic platinum catalysts using electroplating were manufactured to control the material structure of the atomic scale, and through this, catalysts with a new structure were designed and manufactured.
 • A catalyst with high activity and excellent durability is manufactured by controlling the electronic structure and shape of metal through strong metal-support interaction (SMSI). In addition, a study is being conducted to investigate the effect of SMSI on catalyst characteristics using various analysis methods.
 • A platinum monatomic catalyst with the world's highest mass activity was produced using a simple electroplating method, and research is underway to reveal the characteristics of the previously unknown monatomic catalyst.

 • The electrochemical characteristics of various electrochemical reactions (hydrogen generation reaction, oxygen generation reaction, oxygen reduction reaction, etc.) were evaluated by conducting a half-cell experiment under various electrolyte conditions, and the reaction mechanism is being studied. Through full-cell experiments, a research is being conducted to substantially apply and evaluate catalysts, such as fuel cell and water electrolyte cell, as application fields.