High Cost Performance, Stable Discharge Voltage

Powerful Twicell

■Principle of the Nickel-Metal Hydride

Battery

The nickel-metal hydride battery makes electrochemical use of the reversibility of the hydrogen absorption/release reaction in the hydrogen absorbing alloy. The battery uses a nickel oxide compound for the positive electrode, a hydrogen absorbing alloy for the negative electrode, and an aqueous alkaline solution for the electrolyte, which includes such constituents as potassium hydroxide (KOH). During charging, the electrolytic reaction of water causes the hydrogen, which forms in atomic form on the surface of the hydorgen absorbing alloy in the negative electrode, to diffuse into and be absorbed by the alloy (charge reaction). During discharge, the absorbed hydrogen reacts with hydroxide ions at the surface of the hydrogen absorbing alloy to once again become water (discharge reaction). In other words, the active material of the negative electrode reaction is hydrogen, and the hydrogen absorbing alloy acts as a storage medium for the active material. Sanyo has developed a hydrogen absorbing alloy, which absorbs a large quantity of hydrogen at low pressure and which can also release it. Sanyo employs this alloy in the Twicell.

■Features of Twicell Batteries

Extended service life and superior economy

Despite discharge capacity that is virtually equal to that of conventional dry cells, Sanyo Twicell batteries feature minimal internal resistance and exhibit excellent discharge characteristics under high-rate discharge current conditions. With output power much higher than that of dry cells. Twicell batteries can withstand over 500 repeated charge / discharge cycles (conditions stimulated in IEC61951-2(Clause 4.4) , as well as offering outstanding economy. In addition, even though the batteries are stored for a long time, the original capacity is almost recovered by repeated charging/discharging, offering excellent storage characteristics.

Wide-ranging lineup and interchangeability with dry cells

Customized assembled batteries tailored to specific equipment space requirements are also available.

Excellent high-rate discharge performance and overcharge/overdischarge capability

Sanyo's original electrode manufacturing process and current collectors minimize internal resistance, which in turn enables high-rate discharging and guarantees stable discharge voltage.

Structural Design

○＋Positive terminal

(with built-in gas release vent) Cover plate

Gasket

Positive current collector

Casing

(○－negative terminal)

Negative current collector

Spring

Seal plate

Rubber plate

Positive electrode insulation washer

Separator

Negative electrode

Positive electrode

Improved reliability with wide operating temperature and humidity ranges

In addition to displaying only minimal variation in performance over a wide temperature range, their totally-sealed construction gives Twicell batteries high resistance to humidity. Sanyo Twicell batteries are manufactured under strict quality control conditions, and undergo 100% inspection before shipment. This assures superior reliability.

Simple to maintain and strong

The special sealed construction eliminates the need to replenish the electrolyte, for easier maintenance. As Sanyo Twicell batteries may be installed in any direction in equipment, they are exceptionally easy to handle. Moreover, Twicell batteries employ a rigid metal casing for superior resistance to shock and vibration.

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