Highly stabilized thermoelectric performance in natural minerals

Excellent thermoelectric materials can be obtained by various synthesis procedures and optimization strategies, and the elaborately designed composition and microstructure benefit thermoelectric parameter decoupling. Herein, a high-performance mixed natural mineral (CQB), composed by chalcocite, quartz, and bismuthinite, enables direct thermoelectric energy conversion. The network of quartz layers is embedded into the matrix and blocks Cu ion long-range migration by producing the natural rheostat and voltage division circuit. The thermoelectric performance, mechanical strength, and electrical stability of natural minerals are found to be highly superior to the artificially synthesized Cu2S material. Learning from nature, a strategy for blocking mobile Cu+ ions in Cu-based superionic conductors is proposed. Various Cu-based superionic conductors, composited with insulating macroscale glass sheets, have been designed and fabricated, showing highly enhanced electrical stability while maintaining good thermoelectric properties. These findings provide a deep understanding of the role of macroscopic insulating materials in improving the electrical stability of superionic conductors.