Dielectric materials, which store energy electrostatically, are ubiquitous in advanced electronics and electric power systems. Compared to their ceramic counterparts, polymer dielectrics have higher breakdown strengths and greater reliability, are scalable, lightweight and can be shaped into intricate configurations, and are therefore an ideal choice for many power electronics, power conditioning, and pulsed power applications. However, polymer dielectrics are limited to relatively low working temperatures, and thus fail to meet the rising demand for electricity under the extreme conditions present in applications such as hybrid and electric vehicles, aerospace power electronics, and underground oil and gas exploration. Here we describe crosslinked polymer nanocomposites that contain boron nitride nanosheets, the dielectric properties of which are stable over a broad temperature and frequency range. The nanocomposites have outstanding high-voltage capacitive energy storage capabilities at record temperatures (a Weibull breakdown strength of 403 megavolts per metre and a discharged energy density of 1.8 joules per cubic centimetre at 250 degrees Celsius). Their electrical conduction is several orders of magnitude lower than that of existing polymers and their high operating temperatures are attributed to greatly improved thermal conductivity, owing to the presence of the boron nitride nanosheets, which improve heat dissipation compared to pristine polymers (which are inherently susceptible to thermal runaway). Moreover, the polymer nanocomposites are lightweight, photopatternable and mechanically flexible, and have been demonstrated to preserve excellent dielectric and capacitive performance after intensive bending cycles. These findings enable broader applications of organic materials in high-temperature electronics and energy storage devices.

Flexible high-temperature dielectric materials from polymer nanocomposites

The demand for dielectric capacitors with higher energy-storage capability is increasing for power electronic devices due to the rapid development of electronic industry. Existing dielectrics for high-energy-storage capacitors and potential new capacitor technologies are reviewed toward realizing these goals. Various dielectric materials with desirable permittivity and dielectric breakdown strength potentially meeting the device requirements are discussed. However, some significant limitations for current dielectrics can be ascribed to their low permittivity, low breakdown strength, and high hysteresis loss, which will decrease their energy density and efficiency. Thus, the implementation of dielectric materials for high-energy-density applications requires the comprehensive understanding of both the materials design and processing. The optimization of high-energy-storage dielectrics will have far-reaching impacts on the sustainable energy and will be an important research topic in the near future.

Homogeneous/Inhomogeneous-Structured Dielectrics and their Energy-Storage Performances.

Electronics that must operate at extreme temperatures present a unique set of challenges that must be carefully addressed. We review the applications that are calling for high temperature electronics, discuss some of the underlying problems with standard technology, and examine the established and emerging technologies that provide solutions to engineers who wish to design high-temperature electronic systems.

A review of high-temperature electronics technology and applications

Dielectric polymers for electrostatic energy storage suffer from low energy density and poor efficiency at elevated temperatures, which constrains their use in the harsh-environment electronic devices, circuits, and systems. Although incorporating insulating, inorganic nanostructures into dielectric polymers promotes the temperature capability, scalable fabrication of high-quality nanocomposite films remains a formidable challenge. Here, we report an all-organic composite comprising dielectric polymers blended with high-electron-affinity molecular semiconductors that exhibits concurrent high energy density (3.0 J cm−3) and high discharge efficiency (90%) up to 200 °C, far outperforming the existing dielectric polymers and polymer nanocomposites. We demonstrate that molecular semiconductors immobilize free electrons via strong electrostatic attraction and impede electric charge injection and transport in dielectric polymers, which leads to the substantial performance improvements. The all-organic composites can be fabricated into large-area and high-quality films with uniform dielectric and capacitive performance, which is crucially important for their successful commercialization and practical application in high-temperature electronics and energy storage devices. Dielectric polymers are widely used in electrostatic energy storage but suffer from low energy density and efficiency at elevated temperatures. Here, the authors show that all-organic composites containing high-electron-affinity molecular semiconductors exhibit excellent capacitive performance at 200 °C.

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Polymer/molecular semiconductor all-organic composites for high-temperature dielectric energy storage.

Much effort has been invested for nearly five decades to identify and develop new polymer capacitor dielectrics for higher than ambient temperature applications. Simultaneous demands of processability, dielectric permittivity, thermal conductivity, and dielectric breakdown strength dictated by increasing high power performance criteria limit the number of available materials. The present review first explains the advantages of metallized polymer film capacitors over the film-foil, ceramic, and electrolytic counterparts and then presents a comprehensive review on both past developmental effort of commercial resins and recent research progress on new polymers targeted for operating temperature above 150 °C. Some historical background and discussion on the limitation of the commercially available polymer film dielectrics for high temperature applications are also given. In many cases, further development of promising polymers that appear to possess all or most of the important criteria is limited by lack of large scale market incentives but could be of great value to niche applications in the military or aerospace realm.

Polymer Capacitor Dielectrics for High Temperature Applications.

Introduction Many industries are calling for electronics that can operate reliably in harsh environments, including extremely high temperatures. Traditionally, engineers had to rely on active or passive cooling when designing electronics that must function outside of normal temperature ranges, but in some applications, cooling may not be possible—or it may be more appealing for the electronics to operate hot to improve system reliability or reduce cost. This choice presents challenges that affect many aspects of the electronic system, including the silicon, packaging, qualification methodology, and design techniques.

High-Temperature Electronics Pose Design and Reliability Challenges

This paper discusses a very low noise instrumentation amplifier designed specifically for high temperature applications. The device uses a proprietary silicon-on-insulator process that minimizes parasitic leakage currents at elevated temperature. Variance in device parameters are managed to maintain high performance over a wide temperature range. Layout and packaging considerations that would affect long term reliability are addressed. The amplifier is well characterized above 200°C and attains much higher performance than amplifiers not optimized for high temperature operation. Comprehensive reliability testing over temperature has been completed.

An Ultra-Low Noise Instrumentation Amplifer Designed for High Temperature Applications

An increasing number of industries are calling for low power electronics that operate reliably at temperatures of 175°C and higher. Many of these applications require a precision data acquisition signal chain in order to digitize analog data so that it can be collected and processed. We have previously presented a new 600 kSPS SAR ADC that is rated at 210°C to meet these needs. However, the design of the supporting circuitry for a SAR ADC to achieve optimum performance is not trivial, especially over this wide temperature range. In this work we discuss the design of a complete data acquisition circuit building block that will take an analog sensor input, condition it, and digitize it to an SPI serial data stream. We will also discuss some of the practical aspects of fabricating the circuit to survive this harsh environment. This circuit reference design will be published and available off the shelf to designers of harsh environment systems.

A Low Power Data Acquisition Solution for High Temperature Applications

A growing number of industries are calling for low power electronics that operate reliably at temperatures of 175C and higher. Many of these applications require a precision data acquisition signal chain in order to digitize analog data so that it can be collected and processed. We previously presented a characterized signal chain for a single channel of analog to digital conversion designed around a 600ks ps SAR ADC. However, many systems have a multitude of sensor signals that must be acquired at varying sample rates. In this work we discuss two new analog multiplexers rated for 175°C/210°C that allow multiple analog signals to be connected to the ADC input, enabling the design of a precision multi-channel data acquisition system. One multiplexer is designed on a robust dielectrically isolated process for high performance and low leakage over temperature, and one multiplexer is optimized for low power, low voltage applications. We will examine the architecture of these two integrated circuits, ...

Jeff Watson

Papers

A review of high-temperature electronics technology and applications

High-Temperature Electronics Pose Design and Reliability Challenges

An Ultra-Low Noise Instrumentation Amplifer Designed for High Temperature Applications

A Low Power Data Acquisition Solution for High Temperature Applications

High Precision Analog Multiplexers Enable Multi-Channel Data Acquisition in High Temperature Environments