A High Aspect Ratio Micropattern in Freestanding Bulk Pyroelectric Cells

• Published in: Energy technology (Weinheim, Germany) Germany), 2018-05, Vol.6 (5), p.883-898
• Main Authors: Hsiao, Chun‐Ching, Siao, An‐Shen
• Format: Article
• Language: English
• Subjects: Capacitance; Electrodes; Energy conversion; Energy conversion efficiency; Energy harvesting; Equivalence; Heat transfer; High aspect ratio; Induced voltage; Lead zirconate titanates; Micropatterning; Pyroelectricity; Specific heat; Temperature gradients; Thermal capacity; Variation
• ISSN: 2194-4288; 2194-4296
• DOI: 10.1002/ente.201700439

Pyroelectric‐based energy harvesting with the Olsen cycle offers high energy‐transformation efficiency. The pyroelectric effect offers the opportunity to convert temporal temperature fluctuations into usable electrical energy for exploiting abundantly available waste heat. A thinner pyroelectric cell is profitable with regard to generating a higher induced current and a higher charge within a smaller working period owing to a higher temperature variation rate and a smaller thermal capacity. Nevertheless, a thicker pyroelectric cell is advantageous for generating a higher induced voltage over a longer working period owing to a smaller equivalent capacitance and a larger thermal capacity. The use of a high aspect ratio micropattern in a thicker bulk pyroelectric cell is attempted herein to improve the heat transfer and pyroelectric energy transformation by adopting a lower equivalent capacitance to enhance the induced voltage, whereas lateral temperature gradients are introduced to increase the temperature variation rate, the induced charge, and the current. Furthermore, a low‐cost sandblast etching apparatus is adopted to fabricate a high aspect ratio micropattern in thicker bulk lead zirconate titanate (PZT) pyroelectric cells. Within an integral measurement coupled thermal and electrical system, it is demonstrated that relative to a fully covered electrode cell, the high aspect ratio micropattern with an electrode area coverage of 60 % is able to significantly enhance the induced voltage by a factor of 9.3, to increase the induced current by a factor of 5.2, to increase the charge per period by a factor of 3.3, and to increase the stored voltage by a factor of 6.3.