Solid Fuel Type Hydrogen Fuel Cells Deliver High Efficiency and Increased Safety ‐ Ideal for a wide array of applications, from smartphones to portable power generators


ROHM, together with Kyoto-based Aquafairy Corp. and Kyoto University, have co-developed compact, lightweight, high-power hydrogen fuel cells designed to power smartphones and other portable devices. These fuel cells overcome the drawbacks of dry cells, lithium-ion cells, and direct methanol fuel cells, significantly reducing weight and increasing output power while providing a higher level of safety, making it possible to provide power in places where AC power is not available or cannot be used.

Fuel cells can be made smaller, lighter, and more efficient than conventional storage and rechargeable cells, and thus are expected to drive expansion into new markets and applications. In fact, there is already extensive use of fuel cells using methanol and hydrogen. However, methanol fuel cells have several disadvantages that prevent widespread acceptance. Unlike hydrogen fuel cells, it is difficult to increase power output. And hydrogen fuel cells require the use of cylinders, making them harder to handle and hinder efforts towards greater miniaturization.

ROHM, together with Aquafairy, has recently succeeded in solidifying calcium hydride in a sheet configuration using proprietary technologies, generating approximately 4.5 liters of hydrogen from a sheet less than 3cc in volume (measuring 38 x 38 x 2mm), providing a power output of 5Whr. The hydrogen fuel cells are compact and can operate at ambient temperatures, making them suitable for use in smartphone chargers, tablet PCs, as power sources outdoors and in remote areas, and in emergency backup power supplies. In addition, they emit no carbon dioxide or hazardous gases and can be disposed of as general waste.

ROHM, Aquafairy, and Kyoto University will continue to work on assessing reliability and making further improvements, with production targeted for April 2013. The fuel cells will be displayed at CEATEC (held in October 2012 in Tokyo) and Electronica (Munich, November 2012).

In addition to expanding its lineup of hydrogen fuel cells for smartphone chargers, ROHM and Aquafairy, in collaboration with Kinkei System Corp., are also developing fuel cells for powering seismometers in remote areas that prevent the use of traditional power supplies. Compared with conventional lead batteries, the cells reduce weight by 1/4 with same capacity, making it possible to provide 400Whr from a device that weighs only 3kg.

Key Features

1.Compact and lightweight
2.High capacity + high output power
Fully charges a 5Whr smartphone cell in only two hours.
This new series of hydrogen fuel cells uses a solid that creates hydrogen by adding water, generating power through hydro-synthesis. The result is clean power with no harmful byproducts such as carbon dioxide or VOCs (Volatile Organic Compounds). In addition, these eco-friendly fuel cells can be disposed of as general waste.
Hydrogen Generating Sheet
Hydrogen Generating Sheet(2.9cc,3g)
Construction of Hydrogen Fuel Cell
Construction of Hydrogen Fuel Cell
4.Long-term energy storage: 20+ years
Since dry cells and lithium-ion cells have a constant potential difference, they will discharge and the amount of producible electricity will gradually decline even if they are not used, resulting in a shelf life of only 3 to 5 years. In contrast, ROHM's new series of hydrogen fuel cells utilize laminated aluminum in order to prevent degradation, enabling long-term storage for over 20 years without losing energy.

Performance Comparison

  Hydrogen Fuel Cell 1 Lithium-ion Cell 2 Dry Cell 3
Capacity (watt-hour) 5~400 8.9 0.8
Weight (gram) 23~900 44 24
Power Density
217~444 202 36
Charge Not required Required Not required
Storage Over 20 years 3 to 5 years 3 to 5 years
Environmental Impact No harmful substance emitted    
  1. Estimated for fuel cartridges of a smartphone charger and a large capacity fuel cell
  2. Estimated for 18.3 mmø x 65 mm cylindrical cell
  3. Estimated for AA size cell

Application Examples

1. Smartphone chargers
Enclosed Type Enclosed Type Chargers Card Case Type Card Case Type Chargers
  Enclosed iPhone Type Card Case Type
Generation Capacity 5 Whr 5 Whr
Rated Voltage 5.2 V DC 5.2 V DC
Rated Current 0.5 Amax 0.5 Amax
Operating Temperature -5 to 40°C -5 to 40°C
140x65x20 (mm³)
32x65x20 (mm³)
86x52x19 (mm³)
55x47x11 (mm³)
Smartphone chargers Smartphone chargers
2.Large-capacity fuel cells for seismometers (3kg、5.6 liters)
Large-capacity fuel cells for seismometers
Generation Capacity 400 Whr
Rated Power 3 W
Rated Voltage 12 VDC
Operating Temperature -5 to 50°C
25x15x15 (cm³)
20x13x13 (cm³)
3. Portable generators (7kg、17 liters)
Portable generators
Generation Capacity 200 Whr
Rated Power 200W
Peak Power 1,000 W (1 sec.)
Rated Voltage 12 or 24 VDC
Operating Temperature -5 to 40°C
32x33x16 (cm³)
26x4x12.5 (cm³)
6 to 7kg
750 g

Summary by Professor Hirao, Kyoto University (presented at a news conference)

In recent years it has been often suggested we use hydrogen as an energy source since it is a type of clean energy. This brought about the development of hydrogen fuel cell powered vehicles. Since gases emitted from these vehicles contain no nitrogen oxides, particulate matters, carbon dioxide, or other harmful substances, they are expected to significantly reduce environmental pollution and global warming. However, hydrogen requires a large storage volume, making it impractical for automotive applications. Up to now, hydrogen-generating devices are equipped with a resolver that resolves a hydrogen source composed of ammonia and hydrazine through a catalytic reaction in order to supply hydrogen to the fuel cells. But the use of ammonia brings up another problem since it is designated as a deleterious substance.

There is also an increasing demand for fuel cells to become more compact for use as a replacement for AC-DC converters with rechargeable secondary cells used in mobile phones, portable information terminals, digital cameras, and notebook computers.

The hydrogen fuel cells co-developed by ROHM and Aquafairy offer distinct advantages over conventional types of fuel cells in terms of compactness and output power levels. One is a proprietary technology that solidifies calcium hydride (a calcium compound) into a compact sheet configuration in order to stably produce hydrogen through the water drop method, and another is a low-profile, integrated cell-forming technology.

ROHM and Aquafairy have also launched a joint project for a compact, lightweight 400-watt fuel cell system with Kinkei System Corporation, which is expected to become mainstream once the power generation capacity is increased.

We at the laboratory of Professor Kazuyuki Hirao in Kyoto University's Graduate School of Engineering have also joined in the collaboration, and have already discovered a new, high-efficiency, low-priced calcium compound that can be incorporated in fuel cell systems and easily broken down into raw materials and recycled using a special laser. This next-generation regenerative recycling hydrogen-generating agent is currently being developed at the Kyodai Katsura Venture Plaza adjacent to Kyoto University's Katsura Campus.

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