Ultrahigh energy harvesting properties in temperature-insensitive eco-friendly high-performance KNN-based textured ceramics

Mechanical energy-driven wireless charging technology has recently gained increasing attention. In this work, high-performance potassium sodium niobate (KNN)-based textured ceramics and their potential application in energy harvesting devices are systematically investigated. A series of lead-free 0.99K(0.5)Na(0.5)Nb((1-x))Ta(x)O(3)-0.01Bi(Ni2/3Nb1/3)O-3 [KNNTa-BNN] piezoceramics were designed and prepared to search for good comprehensive properties. The comprehensive performance of KNN-based piezoelectric ceramics has reached a new level in T-Ta-9 (d(33) similar to 435 pC N-1, k(p) similar to 71%, T-c similar to 360 degrees C) via the synergy of the textured structure (f((00l)) > 94%) and multiphase coexistence (O-T) near room temperature. Based on the advanced in situ TEM and PFM analyses, it was found that the regular large-scale domains and corresponding poling patterns of the T-Ta-9 can be well maintained at relatively high temperatures (180-330 degrees C), resulting in excellent temperature stability. Hence, the d(33) value of T-Ta-9 can be maintained above 300 pC N-1 over a wide range from room temperature to 300 degrees C, which rarely happens in the previously reported KNN-based materials. More importantly, the piezoelectric circular diaphragm (PCD) vibration energy harvester based on the T-Ta-9 texture ceramic possesses high output voltage (U similar to 13 V) and output power (W similar to 3 mW), and can still maintain above 60% after being heated at 200 degrees C for 30 min. This work represents a significant advancement in the lead-free piezoelectric energy-harvesting field (especially for high-temperature applications) and can provide guidelines for future efforts in this direction.

Automated summary

This work systematically investigates high-performance potassium sodium niobate (KNN)-based ceramics and their potential application in energy harvesting devices. Through the synergy of textured structure and multiphase coexistence, the comprehensive performance of KNN-based piezoelectric ceramics has reached a new level and exhibits excellent temperature stability. The piezoelectric circular diaphragm (PCD) vibration energy harvester based on this textured ceramic material shows high output voltage and output power, maintaining good performance even in high-temperature environments.