What is a water-activated battery?
The water-activated battery is a type of reserve battery that was developed in the 1940s as a non-toxic, environmentally friendly alternative to the commonly used alkaline battery. In addition to plain water and seawater, a variety of other aqueous solutions can be used. Unlike most other batteries, the water-activated battery does not contain heavy metals. Magnesium is usually used as the anode material, but aluminium is also utilized for this purpose. Various chlorides can be used as the cathode material.
How does it work?
The electrode component is stored in a dry inactive state, separate from the electrolyte. As a result of this, the battery has no voltage until soaked or immersed in water. Water forms the electrolyte with ions produced in electrode reactions or released from a soluble salt.
What is it used for?
The water-activated battery has many uses, many of which involve marine or air equipment. It was first utilized for military applications in the 1940s due to its high-energy-density, long shelf life, and good low-temperature performance. The seawater-activated battery is still used today for equipment such as sonobuoys, electric torpedoes, weather balloons, air-sea rescue equipment, and lifejacket lights. Its low environmental impact makes it the go-to power source for radiosondes (measuring device on weather balloons) — they usually fall to the ocean surface or ground and remain there indefinitely, so it is important that their power source does not contain heavy metals.
Why should I use it?
The most unique quality of this battery is its long shelf life. The electrode is stored in a dry state, separate from the electrolyte, thus eliminating the possibility of the battery draining itself before it is activated. It is also a maintenance free battery, lightweight, safe (for the user and for the environment), and its instantaneous activation makes it easy and convenient to use.
One of the most popular examples of a water-activated battery is the Japanese NoPoPo battery released in 2007. The NoPoPo, or “No Pollution Power” battery was popular in the market when it was first released; however, buyers quickly lost interest in it when they became aware of the flaws in the design. It was only manufactured in the AA size, so it had a low power input and would only stay active for a short span of time before draining. The concept was innovative, but as a result of this it was sold at a high price. It was later discovered that the magnesium anode component of the battery interfered with or even deformed the products it was used to power.
Another more successful example is the Aquacell battery. It comes in two sizes: AA and AAA. It weighs in at only 12 grams, making for an overall more convenient product compared to the average alkaline battery. It produces a minimum of 1.5 volts, and 100 mAh on low drain applications. It is a versatile power source and can be used with everyday objects such as clocks, radios, remote controls, toys, flashlights, and the like. The Aquacell creators sought to manufacture a product that was made of sustainable materials. For example, its casing is made of recycled plastic. Additionally, most heavy metals that can be found in other types of batteries are removed from the Aquacell. Although the Aquacell battery is obviously less detrimental to the environment than regular batteries, its creators are still looking for ways to create a better, cleaner product.