Advancing Forward: Breakthrough Chemistry Leading to Next-Gen Energy Storage Instruments

A novel polysulfate compound has been discovered that contributes to the creation of polymer film capacitors. These capacitors are capable of storing and releasing dense electrical energy, outpacing the thermal and electric field limits of present-day polymer film capacitors. Recognition for the image: Yi Liu and He (Henry) Li/Berkeley Lab.

The latest generation of Nobel Prize-winning “click chemistry” reactions has led to the development of flexible polymers that find applications in capacitors and various other areas.

The growing societal need for high-voltage electrical innovations – encompassing pulsed power systems, vehicles, electric planes, and renewable energy solutions – necessitates the creation of a new age of capacitors. These capacitors must be able to contain and discharge vast quantities of energy while enduring harsh thermal and electric circumstances.

A polymer-based apparatus that effectively manages unprecedented amounts of energy, even under extreme temperature and electric field conditions, has been engineered by scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Scripps Research. These devices employ materials created through a next-generation variation of the chemical reaction that earned three scientists the Nobel Prize in Chemistry in 2022.

Polymer Film Capacitors: An Introductory Examination

Polymer film capacitors, utilizing a slender plastic layer as insulation, function as electrical components to store and emit energy in an electric field. They represent roughly 50% of the worldwide high voltage capacitor industry and possess attributes like low weight, affordability, mechanical adaptability, and strong cycle endurance. However, the performance of existing polymer film capacitors reduces significantly as temperature and voltage rise. Thus, developing substances with enhanced heat and electric field tolerance is crucial, and creating polymers through nearly perfect chemistry is a potential solution.

“A new variety of electrically resilient polymers has been added to the landscape. This development offers numerous opportunities for the pursuit of sturdier, superior-performing materials,” stated Yi Liu, a chemist at Berkeley Lab.

Features and Difficulties of the Capacitor

A capacitor must not only endure high temperatures but also maintain robust “dielectric” material properties, meaning it remains a potent insulator under high voltages. The scarcity of materials that offer both thermal stability and dielectric strength is due to the absence of trustworthy and handy methods of synthesis, and a fundamental lack of comprehension of the connection between polymer structure and attributes. “Enhancing the thermal stability of current films without losing their electrical insulation potency remains a constant materials challenge,” Liu noted.

Researchers at the Molecular Foundry and Scripps Research Institute have now met this challenge, using a straightforward and rapid chemical reaction developed in 2014 to replace fluorine atoms in sulfur-fluoride bond-containing compounds with long polymer chains of sulfate molecules known as polysulfates.

The aforementioned Sulfur-Fluoride Exchange (SuFEx) reaction signifies an advanced form of the click chemistry reaction initiated by K. Barry Sharpless, a chemist at Scripps Research, and a two-time Nobel laureate in Chemistry, with Peng Wu, also a chemist at Scripps Research.

Polysulfates, exhibiting superb thermal traits, are molded into pliable, standalone films. Capacitors made from these films, capable of high temperature and voltage, display leading-edge energy storage qualities at 150 degrees Celsius. Such power capacitors are prospective in enhancing the energy effectiveness and trustworthiness of integrated power systems in demanding applications, like electric transportation.

Performance and Potential Impact of Capacitor

Motivated by the remarkable foundational dielectric properties demonstrated by polysulfates, researchers layered extremely thin aluminum oxide (Al2O3) films on the material to construct capacitor devices with augmented energy storage performance. The resulting capacitors revealed remarkable mechanical flexibility, tolerated electric fields exceeding 750 million volts per meter, and operated efficiently at up to 150 degrees Celsius. This contrasts with today’s standard commercial polymer capacitors, which reliably operate only below 120 degrees Celsius.

The discovery has led to fresh prospects in the exploration of strong, high-performing materials for energy containment. “We have contributed profound insights into the mechanisms underlying the material’s exemplary performance,” Wu stated.

Due to the sulfate linkages introduced by the click chemistry reaction, the polymer manages to harmonize electrical, thermal, and mechanical properties. The same approach might also provide a feasible path to new polymers with even greater performance that satisfies more demanding operational requirements.

These polysulfates have emerged as strong contenders to become the new benchmarks in polymer dielectrics. If scientists can overcome challenges in the large-scale manufacturing process for thin-film materials, these devices could significantly enhance the energy efficiency and reliability of integrated power systems in electric vehicles.

Sharpless expressed, “Who would have thought that a fragile sulfate polymer film could resist two of the universe’s most devastating forces: lightning and fire?”

“We are consistently pushing the boundaries of thermal and electrical properties, and hastening the transition from lab to market,” Liu added.

The work was financially supported by the Department of Energy’s Office of Science, the National Science Foundation, and the National Institute of Health and executed at the Molecular Foundry. Reference: “High-performing polysulfate dielectrics for electrostatic energy storage under harsh conditions” by He Li, et al., 18 January 2023, Joule.
DOI: 10.1016/j.joule.2022.12.010

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More about next-generation energy storage devices

• Lawrence Berkeley National Laboratory
• Scripps Research Institute
• Molecular Foundry
• National Institute of Health Funding
• Department of Energy’s Office of Science
• National Science Foundation
• The Journal Article in Joule