The Roll-to-Roll Battery Revolution
By Bill Moore
There's a quiet revolution taking place in the rechargeable battery industry. It is occurring at the confluence of modern nano-technology and 140 year-old printing technology. The result is a small, high-powered, light-weight rechargeable lithium-based battery with unprecedented flexibility.
One of the firms pioneering the lithium revolution is Voltaflex, located in Menlo Park, California. A relatively new start-up, the company licensed two years ago nano-scale polymer technology from MIT that replaces liquid, gel and paste electrolytes commonly found in most rechargeable batteries with a dry solid polymer electrolyte or DSPE. The advantage of this approach is that it now enables batteries to be fabricated at high speed on roll-to-roll machinery similar to modern web-fed printing presses that join the various layers that make up the battery in a continuous run process.
To learn more about this technology, EV World talked with Voltaflex Chief Operating Officer, Glenn Sanders. He explained that the company is small and is presently focused on developing the materials, the synthesis process and the design of the battery.
He noted that the Voltaflex's battery is not intended for high current applications like those found in either portable power tools or electric-drive vehicles. Instead, the company plans to first sell the polymer electrolyte material to other battery makers, then concentrate on offering both component materials for the fabrication of lithium polymer batteries for use in low-current applications including RFID tags and smart cards.
"Our claim to fame is what goes into the center of the battery", he stated, meaning the proprietary dry solid polymer electrolyte.
Unlike competing "dry" electrolytes, which Sanders said are essentially gels in a flexible lattice framework, Voltaflex's electrolyte is synthesized from a liquid compound that contains binders and a solvent. The solvent evaporates in the coating process, leaving behind the actual dry electrolyte material. This eliminates the "mess" or potential leakage problems associated with non-solid materials like gels and pastes.
He said that when it dries is feels somewhat like silicone caulk. This material also has the ability to work at higher temperatures than competing approaches.
"Our polymer actually works better the warmer it gets".
Because Voltaflex licensed their electrolyte chemistry from MIT, as has another lithium battery company called A123, I asked Sanders if they were both using the same technology. He responded that while there are similarities, A123 is using their chemistry to develop batteries for the portable power tool market.
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