2^nd International Conference on Battery & Fuel Cell Technology July 27-28, 2017 Rome, Italy

Sangseok Yu is a Professor of Mechanical Engineering at CNU who is an expert in modeling and simulation of energy system. He was majoring transient heat and mass transfer and dynamic modeling of automotive fuel cell system at University of Michigan Ann Arbor. In particular, he has special interests in control and fault detection of automotive fuel cell system. Recently, he extended his research scope to modeling and simulation of various energy systems.

As an alternative candidate of internal combustion engine, fuel cell vehicle has been actively studied. Compared with internal combustion engine, fuel cell vehicle is more sensitive to the operating temperature that is coupled with water management. Additionally, the durability of fuel cell is also very sensitive to operating temperature. Different from internal combustion engine, the operating temperature window of fuel cell is very narrow, it is necessary to control active control of cooling system. In this study, the control algorithm of fuel cell cooling system is developed that facilitate thermal management strategy. With non-linear comprehensive simulation model of fuel cell system, the analytic redundancy model is developed. The analytical redundancy algorithm is used to determine fault of thermal system by diagnosis of residuals. The sensor errors such as stuck offset and scale of measured value was investigated in terms of change of residual. Result shows that analytic redundancy fault detection algorithm provides decision making information of cooling module. The control algorithm is then readjusted to determine proper operating conditions so that the cooling system is effectively maintained the fuel cell temperature.

This work was done within the MAESTRA strategic project of the University of Padua and aims at developing state-of-the-art technologies, for Vanadium Redox Flow Batteries (VRFBs) which are needed for the production of more efficient and flexible devices, by optimizing cell and stack geometries, power management units and supervisor systems. For developing the experimental investigations, a fully-monitored test facility has been built, rated 4 kW-24 kWh, provided with a 40-cell stack and two 500 L tanks. It is provided with two flow pumps powered by analog-controlled brushless motors, a bidirectional power management system, a Labview-based battery management system (BMS), multi-voltage and current meters, pressure and voltage measurements. The test program include stack voltage vs. SOC (state of charge) in charging and discharging, electric power flow, temperature analysis, distribution of stack voltage, polarization curves, electrochemical impedance spectroscopy (EIS), efficiency measurements, and aging effects. The experimental campaign is supported by extensive numerical analyses. Recently, two battery topologies have been studied and compared. In the conventional series stack, cells are connected electrically in series and hydraulically in parallel by means of bipolar plates. The alternative topology consists of cells connected in parallel inside stacks by means of monopolar plates, in order to reduce shunt currents along channels and manifolds. Channeled and flat current collectors interposed between cells have been considered in both topologies. In order to compute the stack losses, an equivalent circuit model of a VRFB cell was built from a 2D FEM multiphysics numerical model based on Comsol®, accounting for coupled electrical, electrochemical, and charge and mass transport phenomena. Shunt currents were computed inside the cells with 3D FEM models and in the piping and manifolds by means of equivalent circuits solved with Matlab®. Hydraulic losses were computed with analytical models in piping and manifolds and with 3D numerical analyses based on ANSYS Fluent® in the cell porous electrodes. The alternative topology with channeled current collectors exhibits pumping and shunt current losses one order of magnitude lower than a conventional battery rated at the same power, resulting in a round-trip efficiency 10% higher, as compared to the conventional topology.

S W Kim has been studying lithium secondary batteries at Hanbat National University as M. S candidate. He intensively research on gel polymer electrolyte and lithium metal anode using lithium secondary component.

To increase lithium secondary batteries (LiSBs) energy density, commercialized graphite as anode material has limits due to their low capacity. Therefore, Li-metal is an ideal anode material for LiSBs due to its extremely high theoretical specific capacity, low density and the lowest negative electrochemical potential. However, unpredictable dendritic lithium growth and limited Coulombic efficiency during Li charging/discharging in these batteries have prevented their practical applications. In order to solve this problem, in our previous work, micro-patterned Li-metal anode was used in LiSBs material. LiSBs using micro-patterned Li-metal anode show good cycle life and low resistance during charging/discharging process with low current density (about 0.5 C). But, because of generating bulky lithium deposition in the micro-patterned Li-metal hole during charging/discharging process with high current density, the cell still shows bad cycling life and low Coulombic efficiency. In this paper, in order to enhance cycle life with high current density, composite protection layer (CPL) is introduced in LiSBs using micro-patterned Li-metal. The cell shows good cycling life and low resistance during high current charging/discharging process; because of mechanical suppressing of generating bulky lithium deposition in the macro-patterned Li-metal hole and enhancing of interfacial stability between electrode and electrolyte.

Hyunkyu Jeon has expertise in separators of lithium secondary batteries. He developed a low cost, facile, effi cient, and environmentally friendly water-based method to prepare inorganic/polymer composite coating layers on separators after years of experience in research in Hanbat National university energy united laboratory.

Many commercial ceramic coated separators have been introduced to improve safety of large format lithium metal secondary battery even at various abnormal conditions. However, because of hydrophobic surface of commercial olefi n separators, nonpolar organic solvents had to be used. Typically, organic solvents are expensive and toxic. Th is is why water-based ceramic coating method should be developed. Here in, we introduce a plasma treatment technique, to make aqueous ceramic coating separator. An atmospheric radio frequency (RF) plasma generator was used for the surface modifi cation of the bare PE separators. Th e plasma treatment changed the surface of the polyethylene (PE) separator from hydrophobic to hydrophilic. Water-based coating slurry was uniformly coated on PE separators without defects. Recently, we introduced aqueous ceramic coated technique using surfactant. Here, to investigate the eff ect of plasma treatment process, we used this surfactant ceramic coated separator as control cases. As a result, plasma-treated ceramic-coated separators (plasma CCSs) exhibit superior power capability and cycle performance (plasma CCS maintained 94.7% of the initial discharge capacity up to the 1000th cycle at C/2, whereas bare PE’s remained high only up to the 300th cycle) in unit cells based on lithium metal anodes.

Dahee Jin has her expertise in evaluation and passion in lithium secondary batteries in Hanbat National University as M.S. Candidate. She intensively research on Electrolyte additive and Lithium metal anode using lithium secondary batteries component.

To develop a pollution-free alternative energy source, which is the solution of the environmental and energy problems, and to strengthen the fuel effi ciency regulation of motor vehicles to reduce greenhouse gas, as an important technology to solve these problems, implementation of the electric vehicle has emerged as an essential. Accordingly, the importance of the use of a lithium secondary battery that has an excellent cycle performance, high energy density and high-power density is increased. In this respect, it has replaced the LiCoO2, graphite which has been conventionally used for Li (Ni, Co, Mn) O2. However, Li (Ni, Co, Mn) O2 is not showing good electrochemical performance at high voltage and temperature since decomposition of electrolyte and dissolution of transition metal. To solve this problem, studies have been made to improve using ceramic doping and surface coating. However, there is a problem of increase cost in the additional manufacturing process. Herein, we developed a facile cathode fabrication technique by introducing well-known alumina (Al2O3) ceramic fi ller during a cathode electrode preparation step. Th e eff ect of Al2O3 ceramic fi ller was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). Th e cycle performance of coin cells has lithium nitrate in the electrolyte at changing cut-off voltage. Th e coin cell added the ceramic fi ller exhibited an enhanced cycle performance at high voltage (3.0~4.5V vs. Li/Li+, C/2) and high temperature (60ºC).

D Song has been studying about Lithium Secondary Batteries at Hanbat National University as MS candidate. He intensively researches on silicon anode and lithium metal anode using lithium secondary component. He has improved the adhesion of electrodes through research and other new methods so far. His research will greatly help in the commercialization of silicon.

Although silicon (Si) have received worldwide attention as a promising anode candidate because they are not only able to provide high theoretical capacity ~3500 mAh g-1 but also cheap and environmentally friendly source, a successful implementation of Si anode based lithium-ion batteries (LIBs) has been hindered so far. Th is is because Si anodes suff er from huge volume change (c.a. 300%) during cycling. To improve cycle performance of Si anode based LIBs, the mechanical stress should be effi ciently alleviated. In this study, we developed surface modifi ed conductive additive by using a mussel-inspired polymeric material: polydopamine (PD). Due to hydrophilic moiety of PD coating layer, PD-treated Super-P was well dispersed in the water. Th us, we could use polyacrylic acid (PAA) as a polymeric binder. PD-treated Super-P achieved highly improved cycle performance of Si anodes. Using FT-IR, we verifi ed that the improved cycle performance is attributable to the newly formed covalent bonds between the amine group in PDtreated Super-P and the hydroxyl group in PAA. Furthermore, we evaluated adhesion property of anode composite using a surface and interfacial cutting analysis system (SAICAS). PD-treated Super-P showed the highest adhesion value compared to bare Super-P.

Qingpeng Guo is a Doctoral student in the College of Aeronautics and Materials Engineering, National University of Defense Technology, China. He studies energy materials and their electrochemistry, and the current research direction is the design of safe electrolyte for lithium batteries including ionic liquid electrolytes, gel polymer electrolyte and solid polymer composite electrolyte as well as their applications in lithium storage and conversion.

A new approach to solve the leakage problem and ameliorate interface performance of the lithium battery is proposed here. We designed quasi-solid electrolytes containing polymer matrix of poly(vinylidene fl uoride) (PVdF), ionic liquid of 1-ethyl-3- methylimidazolium triluorome thanesufonate (EMITFSI) and bis(trifl uoromethane)sulfonimide lithium salt (LiTFSI) as the main components with solution casting method to form electrolyte membrane (ILQsPEs). Meanwhile, the small molecule of solvent EC and PC were used as additives for the modifi cation in ionic liquid. ILQsPEs were found to have considerable ionic conductivity aft er activated by the mixed solvent, which represents a very good compromise high safety and good performance. At the same time, the Li/LiCoO2 cell with this electrolyte exhibit certain cycling performance, the results indicate that a small amount of free-active solvent molecules on the electrolyte surface enables the construction of an "ionic liquid bridge" between the electrode material and the quasisolid electrolyte, which ameliorated the interface and accelerated the migration of Li+ between the electrode active material and the electrolyte. Th e most of liquid components was confi ned in the polymer matrix to avoid the occurrence of battery leakage, which is suggested as a promising for high safer lithium batteries.