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Energy Storage Materials
Hydrogen can be an alternative to traditional energy sources such as oil, coal and natural gas. It has been the focus of research and development efforts in the world. Hydrogen is believed to be able to meet the increasing demand for energy and decelerate global climate change. In fact, hydrogen can be produced from various sources such as fossil fuels, renewables and water by means of nuclear, wind, solar, tidal or geothermal energy. When hydrogen is converted into energy, water is the only exhaust product. It is thus extremely environmentally friendly as an energy carrier.
Although hydrogen has obvious benefits, an immediate incorporation of hydrogen into the world economy has a number of difficulties to be solved. Differently from oil and natural gas, hydrogen has no large-scale infrastructure supporting its transportation. Hydrogen is largely used by chemical and refining industries. However, the cost of hydrogen storage and delivery is too high for much energy to be stored and transported using hydrogen as a major energy carrier.
The hydrogen economy infrastructure is made up of five key factors - production, delivery, storage, conversion, and applications. While hydrogen production and conversion are technologically feasible, its delivery and storage face serious challenges.
There are several kinds of hydrogen storage method; pressure storage, cryogenic storage, metal hydride storage and carbon nanotube storage etc. Among these hydrogen storage methods, metal hydride storage can store more hydrogen per unit volume and is safer than pressure storage and cryogenic storage. To evolve hydrogen from the hydride, waste heat can be used. In addition, metal hydride absorbs and desorbs selectively hydrogen and thus hydrogen with high purity can be produced.
Our energy storage laboratory has studied on the metal hydrides, which have these advantages, as hydrogen storage materials.
As the industry has developed highly and we are living in information society, much attention is drawn to portable cellular phone, computer and camcorder, and electric vehicles without air pollution, and thus batteries with high energy density, small size, light weight, and high charge and discharge capacity are in dire need. Lithium secondary battery is one which can satisfy theses need. Our laboratory has also studied on cathode materials for lithium secondary battery.
Ni-MH (metal hydride) battery is a kind of secondary (rechargeable) battery, which is commercialized. Interconnect is one of the important parts of fuel cell, which is a battery converting directly chemical energy, produced by the oxidation of fuel, into electric energy. High-temperature superconductor can be used for magnetic levitation train, electric power generation and transportation system and medical equipment such as MRI (Magnetic Resonance Imaging).
In addition to hydrogen storage materials and cathode materials for lithium secondary battery, our research has been engaged in Ni-MH (metal hydride) electrode, interconnect materials for fuel cell and high-temperature superconducting materials.
For the research of the above energy storage materials, design of alloys and materials, optimization of synthesis process, analysis of structure of materials, observation of microstructure, and estimation of properties are being performed. The materials being studied in our energy storage laboratory and their applications are summarized as follows;
Hydrogen Storage Materials
Improvement of hydrogen storage capacity and hydriding and dehydriding rates of Mg-based alloys, Mg2Ni and FeTi intermetallic compounds by reactive mechanical grinding, solid-state reaction method, or induction melting.
Application: Hydrogen storage system,
Cooling and heating system using metal hydride heat pump,
Purification and separation of hydrogen from hydrogen and gas mixture,
Separation of hydrogen isotopes,
Hydrogen compressor,
Hydrogen supply for fuel cell.
Cathode Materials for Lithium Secondary Battery
Development of LiNiO2, LiCoO2, LiMn2O4-type cathode materials with high capacity and excellent cycling performance.
Application: Cathode material for lithium secondary battery,
Battery for portable electronic devices,
High-power lithium secondary battery for hybrid automobile,
Electric scooters and bicycles.
Ni-MH (Metal Hydride) Electrode
Development of ZrMn2-type metal hydride electrode with high capacity and excellent cycling performance.
Application: Anode material for Ni-MH secondary battery.
Interconnect materials for fuel cell
Oxidation behavior with thermal cycling of Crofer22 APU specimens with different roughness
Application: fuel cell.
High-Temperature Superconducting materials
Improvement of the current density of Y(Yb)-Ba-Cu/Ag Alloy Ribbons prepared by melt spinning.
Application: Magnetic levitation train,
Electric power generation and transportation system,
Superconductor bearing system,
SQUID (Superconducting Quantum Interference Device),
MRI(Magnetic Resonance Imaging),
NMR(Nuclear Magnetic Resonance),
Magnetic screening equipment.
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