Green battery that keeps going

Dr Karl Kordesch, the man who came up with the single use alkaline battery, has developed a new rechargeable alkaline manganese dioxide/zinc battery that, it is claimed, will be cheaper and more environmentally friendly.

Most batteries for equipment like radios, Walkmans, watches and toys are just thrown away, often with damaging consequences for the environment. That is because they use materials such as mercury, cadmium or nickel.

On the other hand, rechargeable batteries have not really taken off, mainly because of the costs associated with them. They are not easy to use and are limited to low voltage applications. They cannot be used in certain applications, such as portable computers.

Marketed in Europe by the Battery Innovation Group (BIG), the rechargeable alkaline manganese dioxide/zinc battery system overcomes these difficulties. It can replace nickel/cadmium and nickel/metal hydride cells in low to medium power applications with a much improved charge retention at higher operating temperatures and intermittent use.

The BIG battery also copes well where intermittent operation at moderate loads and a shelf-life at elevated temperatures is required. And while conventional rechargeable batteries need to be completely flat before reloading, this is not a requirement with the new type.

In the design of the battery, the positive electrode consists of multiple cathode rings which are forced under high pressure to a slightly oversized diameter and then inserted into the nickel plated steel can. A typical cathode formulation consists of electrolytic manganese dioxide, graphite and additives that improve cycle life and facilitate hydrogen recombination. Gelled zinc anodes are prepared from atomised zinc powders using a proprietary method developed by Kordesch that involves deposition of indium on the zinc particle surfaces. The separator is a laminate of a non-woven material and cellophane. A brass nail functions as a negative current collector.

BIG cite the Gameboy toy, a portable device that regularly takes four batteries, as a typical example of how the new battery can save the customer money as well as protect the environment.

The new rechargeable battery costs about three times as much as a single use 1.5V battery, and uses a recharging device that costs about £15. The batteries need to be recharged every seven hours, yet four of them will provide 1750h of playing time. For the same amount of playing time, the consumer would need to purchase 175 single-use alkaline batteries, 171 more of which would land up in waste sites.

{{Battery Innovation GroupTel: Germany +49 23 04 97 600Enter 435}}