Ultrafast and Cost-Effective Fabrication of High-Performance Carbon-Based Flexible Thermoelectric Hybrid Films and Their Devices

Dueto their cost-effectiveness and industry-scale feasibility,carbon-based composites have been considered to be promising thermoelectricmaterials for low-grade power generation. However, current fabricationsfor carbon-based composites are time-consuming, and their thermoelectricproperties are still low. Herein, we develop an ultrafast and cost-effectivehot-pressing method to fabricate a novel carbon-based hybrid film,which consists of ionic liquid/phenolic resin/carbon fiber/expandedgraphite. This method only costs no more than 15 min. We found thatthe expanded graphite as the major component enables high flexibilityand the introduction of phenolic resin and carbon fiber enhances theshear resistance and toughness of the film, while the ion-inducedcarrier migration contributes to a high power factor of 38.7 & mu;Wm(-1) K-2 at 500 K in the carbon-basedhybrid film. After the comparison based on the ratios between thepower factor with fabrication time and cost among the current conventionalcarbon-based thermoelectric composites, our hybrid films show thebest cost-effective property. Besides, a flexible thermoelectric device,assembled by the as-designed hybrid films, shows a maximum outputpower density of 79.3 nW cm(-2) at a temperature differenceof 20 K. This work paves a new way to fabricate cost-effective andhigh-performance carbon-based thermoelectric hybrids with promisingapplication potential.

Automated summary

An ultrafast and cost-effective hot-pressing method was developed to fabricate a novel carbon-based hybrid film consisting of ionic liquid/phenolic resin/carbon fiber/expanded graphite, taking no more than 15 minutes. The hybrid film showed high flexibility due to the presence of expanded graphite, and the introduction of phenolic resin and carbon fiber improved its shear resistance and toughness. The ion-induced carrier migration contributed to a high power factor of 38.7 μWm(-1) K-2 at 500 K. Comparing with current conventional carbon-based thermoelectric composites, the hybrid film exhibited the best cost-effective property based on the power factor, fabrication time, and cost ratios. Additionally, a flexible thermoelectric device assembled with the hybrid films achieved a maximum output power density of 79.3 nW cm(-2) at a temperature difference of 20 K. This work provides a new approach for fabricating cost-effective and high-performance carbon-based thermoelectric hybrids with promising application potential.