A solution has to be found, and NOW. Zinc Matrix Power are developing rechargeable silver-zinc batteries that contain NO lithium or flammable liquids. The chemistry is based on silver, zinc and water so there’s not the issue of ‘thermal runaway’ or fire. Another interesting result of this chemistry is that the batteries are not toxic for the environment. This means that when they no longer are useful as batteries the components can be easily recycled.
- 1.5 volts nominal output, closely matching alkaline primaries
- Up to 200 Wh/kg specific energy
- Best in-class volumetric energy and power 500 Wh/l
- Very low self discharge
- No memory
- Environmentally friendly recyclable materials
- Intrinsically safe water based chemistry and zero pressure packaging
Advanced Rechargeable Alkaline Zinc Technology Details
The Alkaline Zinc Primary Battery is by far the most popular source of sealed electrical power throughout the world. The world market for disposable batteries continues to rapidly grow, however, many modern devices require so much energy and power that it would cost several dollars per day to operate them on Alkaline Zinc Primaries.The first sealed rechargeable replacement for Zinc Primaries was the sealed Nickel-Cadmium and, later, Nickel-Metal-Hydride Batteries. These batteries can provide a very economical alternative to primaries at pennies a day operating cost, but they have several shortcomings. First, they store only one quarter to half as much energy as common alkalines so they have short run time in the equivalent size and weight of alkalines. Second, they rapidly self discharge, that is they lose energy whether they are used or not. An even more serious side effect of self discharge is voltage depression. Nickel Batteries start with a lower voltage than Alkalines, often just marginally enough to run a device when freshly charged. Just a day or two after charging their voltage may fall below the operating range of the user device resulting in very little to no run time. To complicate matters, Nickel electrodes exhibit memory effect, that is they lose capacity if not periodically deep cycled, however high self discharge causes users to constantly recharge them without fully discharging them first on a properly designed ‘Battery Conditioner.’ This simply increases the memory effect.
Sealed gelled versions of the Lead-Acid car starter battery are also available commercially. These batteries have lower energy, lower power and less cycle life than NiCd or NiMH batteries, but, they have low self discharge, no memory and are very abuse tolerant, so they have found widespread use in medium and large battery configurations such as wheelchairs, electric scooters, uninterruptible power supplies, emergency lighting, etc., etc.
Battery researchers turned to Lithium in the 80’s. Lithium Metal is extremely light and extremely energetic, factors which are very good for battery design. Unfortunately, Lithium Metal spontaneously explodes on contact with water and must be kept super dry in anhydrous organic solvents. If Lithium gets above 146o centigrade it will spontaneously react even with these organics, often explosively.
Lithium ion and Lithium Polymer battery designers have successfully tamed this behavior with a wide range of internal and external safety systems and interlocks. By carefully optimizing these safety systems, battery designers have produced high energy Lithium rechargeable batteries that match or even marginally exceed the energy density of Alkaline primaries. However, these safety interlocks function by sensing high current draws and internal temperature rises. Both of these effects are indistinguishable from the high peak power demands of many types of electronic systems.Recently international and US transportation agencies have imposed a strict 8 gram limit on the size of lithium batteries in passenger aircraft and now require new designs of lithium batteries after January 1, 2003 to be rigorously safety tested. See Lithium Safety for details.
Zinc Matrix Technology
Zinc metal is nearly ideal as a battery fuel. It is non-toxic. In fact, zinc oxide is used as the main ingredient of baby powder! It is plentiful and inexpensive and, most importantly, it produces high energy and power when discharged in an alkaline water based electrolyte. It is, therefore, no accident that the majority of the batteries in use in the world today operate by discharging zinc to zinc oxide.Zinc metal has two characteristics which make it extremely difficult to recharge. Zinc oxide is highly soluble in alkaline electrolyte and zinc recharges at about the same voltage that causes water to break down into hydrogen and oxygen. These two phenomena account for the fact that there are virtually no rechargeable zinc batteries on the market today.
Written by Cecilia