Thermal switches and diodes could enable smarter control of heat in future technologies

As electronic devices, batteries, and energy systems become increasingly compact and powerful, managing heat is becoming a growing challenge. Conventional thermal management technologies mainly focus on dissipating or retaining heat. But future systems may need something more adaptive—the ability to actively control when, where, and in which direction heat flows.

A review published in Thermo-X examines how thermal switches and thermal diodes could provide this dynamic control and enable new approaches to thermal management in energy and information technologies.

Thermal switches can reversibly transition between high- and low-thermal-conductance states, allowing heat flow to be turned "on" or “off.” Thermal diodes, meanwhile, preferentially conduct heat in one direction. These capabilities offer a way to move beyond conventional passive thermal management toward active and adaptive control of heat.

The authors review recent advances in the design principles and underlying mechanisms of thermal switches and diodes, including approaches based on mechanical actuation, phase transitions, electrochemical modulation, and thermal radiation. They also assess how these technologies could be integrated into practical systems.

One promising application is battery thermal management. Batteries need to operate within an appropriate temperature range: low temperatures can reduce performance, while excessive heat accelerates degradation and raises safety concerns. Thermal switches could help retain heat when batteries are cold while enabling efficient heat dissipation at elevated temperatures.

The review also highlights opportunities in solid-state cooling, building energy management, and information technologies. In increasingly miniaturized electronics, dynamically regulating heat pathways could help address localized and rapidly changing thermal loads. Thermal switches and diodes may also serve as fundamental components for thermal logic and information processing, where heat flow itself is used to represent or manipulate information.

Despite significant progress, the authors note that many thermal switches and diodes remain at the proof-of-concept stage. Challenges including scalability, durability, manufacturing complexity, and system-level integration must still be addressed before widespread practical deployment.

Looking ahead, the review calls for greater attention to real-world operating conditions and integration with existing thermal systems. By combining advances in materials science, device engineering, and thermal management, thermal switches and diodes could help transform heat from something that is simply dissipated into a flow that can be actively controlled and directed.