What is a battery separator?

Battery separator is one of the main components of a battery, bearing the role of separating cathode and anode.

Why is PA9T fiber used in separators?

Heat resistance

Secondary batteries are used by repeating charging and discharging cycle over and over again. Separator must be heat durable to ensure long service life of batteries. PA9T fibers with high glass-transition point (※1) is stable even under high temperature, making it suitable for use as secondary battery separator.

※1 The temperature at which the molecules start thermal-induced oscillation. When it reaches this temperature, intermolecular connections of high molecular substances start to weaken, and in the end become vulnerable to change.

Chemical resistance

As the inside of a battery is filled with strong chemical solution, appropriate chemical resistance is required for separators. PA9T fiber has high chemical resistance and is suitable for secondary battery separator.

Why is EVOH fiber used in separators?

Function as a binder fiber

Separators are sheet-shaped. To create sheets (papers) from fibers, adhesives that bond the fibers together will be necessary. EVOH fibers have a melting point close to 170deg C when dry, but when it is wet, it melts at around 100deg C. Making use of this property, it is used as a binder fiber that works as an adhesive in the papermaking process.

Chemical resistance（Stable even by contact with chemicals）

As it is used as a separator, appropriate chemical resistance is required. EVOH fiber has chemical resistance strong enough to resist the chemical solution filled inside the secondary battery.