Toho Tenax Develops Gas Diffusion Layer For Fuel Cells Using Carbon Fiber Fabric

Tokyo, Japan — September 15, 2010 — Toho Tenax Co. Ltd., the core company of the Teijin Group’s
carbon fibers business, announced today that it has developed a gas diffusion layer (GDL) made of a
carbon fiber fabric for use as an electrode component for fuel cells. The new GDL will be marketed
from late September.

The new fabric-type GDL exhibits better flexibility and strength than commonly used
paper-type GDLs, which are carbon fiber sheets impregnated  with resin or other materials.
With the new fabric structure, roll-to-roll processing can be performed at high speeds, enabling a
reduction in user costs. Also, since resin or such is not needed, water permeability can be further
improved, enabling higher output of fuel cells.

The new product also has lower contact resistance than conventional fabric-type GDLs,
achieved by creating a uniform textile surface using various technologies refined by Toho Tenax,
such as spinning, weaving, and carbonizing technologies. With low contact resistance, further
improvements in fuel cell performance can be expected.

The new GDL will be available in two thicknesses: 260μm and 320μm. Based on market growth,
Toho Tenax anticipates sales volume of 1 billion yen by 2015. Also, based on market needs for
smaller fuel cells, the development of ultra thin fabrics with thicknesses of 200μm and less is

In recent years, demand has increased for mobile devices, stationary power supplies, and
fuel cell vehicles, focusing attention on fuel cells that can be used as an energy source. Since
GDL is a key part of the electrode in fuel cells, supplying hydrogen and oxygen fuel to them while

electrons generated and discharging water produced at the membrane, it must be able to
conduct electricity and be water permeable. Carbon fiber sheets are generally used for GDLs as they
satisfy these performance requirements.

About the Teijin Group

Based in Tokyo and Osaka, Japan, Teijin is a global technology-driven group operating in six
main fields: high-performance fibers (aramid fibers and

carbon fibers); polyester fibers; films and plastics; pharmaceuticals and home health care;
trading and retail; and IT and new products. Teijin Limited, the holding company for the Teijin
Group, is listed on the Tokyo and Osaka stock exchanges. The group had consolidated sales of USD
8.5 billion (JPY 765.8 billion, USD 1=JPY 90) in fiscal 2009 and employs 18,778 people worldwide,
with 156 companies around the world. Please visit

About Toho Tenax

Toho Tenax is the core company of the Teijin Group’s carbon fibers business. The Toho Tenax
Group is a leading carbon fiber manufacturer worldwide with an annual production capacity of 13,900
tons in Japan, Germany and the USA.

Posted on September 21, 2010

Press release courtesy of Toho Tenax