Testing key to solid state polymer development
EEStor in Cedar Park, Texas, has been developing a ceramic polymer technology based on a Composition Modified Barium Titanate (CMBT) material that can make capacitors and supercapacitors that handle higher voltages in smaller packages.
“We’ve got to fix energy storage globally, it’s an imperative and it’s a good opportunity for us,” said Ian Clifford, president and CEO of EEStor. He recognised early on that testing was essential for the credibility of the material, especially for a licensing business. One of the challenges is that the CMBT can be added to a range of other materials with differing performance.
“Early on we started working with Intertek on test who have a lot of experience with capacitor type devices and we are now completing our phase 9 testing with them, expanding it to include two other organisations that specialise in high voltage capacitors to make sure we have a credible, repeatable process for the data,” he said. “We wanted to push the technology as far as we could and get independent certification of the technology and turn heads,” he said. “You kind of only get one chance and we wanted to put our best foot forward, and its very important to be ready. We’ll publish the Phase 9 results in the next couple of weeks with a lot of focus on that.”
“A battery is still out of our reach but in the meantime we have a product that stores more energy than other materials.,” said Bryan Kelly, vice president of production at EEStor. “CMBT mixed with glass can maintain a higher dielectric constant at voltage than other dielectrics. The Phase 7 material showed the nature of the material, a lead free relaxer with low residual polarisation, which is unique and means you get more energy out in discharge.”
Adding the glass changes the thermal response of the capacitor, allows a higher voltage and lowers the sintering temp so instead of precious electrodes capacitor makers can use base metal electrodes. This allows the MLCCs to be significantly smaller than aluminium electrolytic capacitors and lower cost, says Kelly, especially important at a time when MLCCs are increasingly in short supply.
The company now has several products lines, with a glass CMBT hybrid for MLCC and a pure CMBT Y5V for MLCCs in the decoupling capacitor market, as well as a version for supercapacitors.
“With the CMBT loaded polymers at room temperature we are approaching energy densities of supercapacitors. We are completely electrostatic with high voltage so we have 3K and 4kV parts with an energy density that’s suitable for the low end of the supercapacitor market,” said Kelly. “On the ceramic side we can store 1.4wh/l and we are not going to wear out over time,” he said.
“From our perspective the development is all concurrent, the advancements we are making on the polymer side are daily and dramatic, so we are very excited about those material developments,” said Clifford.
The technology is now rolling out to manufacturers.
“Our intention is not to produce end devices but production of the CMBT, either through licensing or joint ventures. We are negotiating with tier 1 multibillion dollar organisations, the top 3 players, so we are getting interest at that level. Capacitor part manufacturing is happening in Europe and companies are definitely interested in the high voltage operation,” said Clifford. “The raw material and CMBT production can happen anywhere in the world, there are supplies of barium titanate and dopants are available around the world.”
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