Benchmarking of piezoceramic materials for generator application

The use of solid state generators based on piezoceramic is widely known. More than 40 years ago, the first gas igniters using piezoceramic elements came on the market. Later on in the 1980s the first idea to harvest energy from structural vibration and power a radio transmission circuit were published. Since the power requirements of state of the art electronics has significantly been reduced, this idea comes again more in focus of interest. At the moment there are more than 200 different piezoceramic materials from more than 15 different vendors are available. Most of the materials are developed for sensing, actuation and ultrasound application. The here considered question is: Are there any interesting materials for generation application? Therefore our approach is to analy ze those to find application relevant material. System analysis shows that three key parameters are of major interest. First is energy transfer rate. Typically piezoceramic materials have efficiency from 30% up to 50%. Here it would be always the best to choose the material with the highest energy transfer rate. But the second parameter represents voltage-current relation. This is of great importance, because choosing two materials having the same energy output but the voltage-current relation differs by a factor of 5. The final parameter is degradation, meaning mechanical load induced depolarisation. The presentation gives a survey of the obtained data set in correlation to commercial piezoceramics. The investigation showed especially, that materials with high energy transfer rate suffer under depolarization even under low mechanical load, which excludes these materials from practical applications.