ReVolt, a Swiss spinoff from a Norwegian research firm, promises to triple the driving range of electric cars while lowering costs and increasing battery reliability and safety.
These claims would be remarkable for any battery. What makes the company even more unique is that ReVolt is developing larger-scale and more reliable batteries using zinc-air technology, which has been abandoned by most energy storage companies for being too fickle for long-term recharging.
Typically, zinc-air cells give out after a couple months, making them fit only for button-cell applications like watches and hearing aids. ReVolt is hoping to turn this around, making them work through 500 and 2,000 recharge cycles. If it can, it will scale them up for electric vehicle and grid storage capacities, and offer them at a more affordable price than competing battery makers.
By combining hypercapacitors and lithium-ion batteries, ReVolt supplies the fast-discharge “peak” power in an automotive system — that “oomph” you feel when you stomp on the gas. Then it uses zinc-air cells as the general motive force that a Tesla Motors’ Roadster could use to travel over 600 miles on one charge.
If zinc-air batteries become a reality, cell phones could go unplugged for days at a time. Laptops would become more portable that ever. Black & Decker cordless blenders could be used in true wilderness conditions without backup batteries. With three times the storage potential of lithium-ion batteries of similar size, zinc air batteries could make almost any appliance imaginable more useful and reliable. On top of that, the cells use less exotic and more stable materials, making them cheaper.
This technology has been around for years. So what’s the holdup?
Zinc air cells tend to jam after you recharge them several times. The zinc branches out from the electrode and shorts out, the electrolytic solution gets drawn into the porous “air” electrode and clogs it, the humidity changes in the battery. In a word, they are fragile. ReVolt is hoping to make them less so, reaching for commercial viability with 500 to 2,000 recharge cycles. Right now, the highest number reached is 100 before the cell dies. The company seems to be well on its way.
When ReVolt announced that they were developing a zinc slurry pumping device inside its batteries to prevent clogging, people took notice. The technology is still in the midst of being scaled for EV and grid applications, and refined for long-term durability. In order to make them suitable for EV use, the cells will have to be flattened for easy packaging and installation — not an easy task in itself.
Given the progress the company has made so far, the question isn’t “if” it can make zinc-air a rechargeable energy source, it’s “when.” With an estimated two to five years left in the development phase before EV batteries and grid storage solutions become viable, there is plenty of time for competitors to release their own breakthroughs.
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