Flexible polymers made from a new generation of Nobel Prize-winning “click chemistry” reaction are finding use in capacitors and other applications.
Society’s growing demand for high-voltage electrical technologies—including pulsed power systems, electrified automobiles and aircraft, and renewable energy applications—demands a new generation of capacitors that store and deliver large amounts of energy under intense thermal and electrical conditions.
A new polymer-based device that efficiently handles record amounts of energy while withstanding extreme temperatures and electric fields has now been developed by researchers at DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Scripps Research. The device consists of materials synthesized through a next-generation version of the chemical reaction for which three scientists won the prize Nobel Prize in Chemistry 2022.
Polymer film capacitors: a quick overview
Polymer film capacitors are electrical components that store and release energy within an electric field using a thin plastic film as an insulating layer. They account for about 50% of the global market for high voltage capacitors and offer advantages including light weight, low cost, mechanical flexibility and strong recyclability. But modern polymer film capacitors drop dramatically in performance as temperature and voltages increase. The development of new materials with better tolerance to heat and electric fields is critical. Creating polymers with near-perfect chemistry provides a way to do this.
“Our work brings a new class of electrically strong polymers to the table. It opens up many possibilities for exploring more robust, high-performance materials.
– Yi Liu
“Our work adds a new class of electrically strong polymers to the table. It opens up many possibilities for exploring more robust, high-performance materials,” said Yi Liu, a chemist at Berkeley Lab and senior author of the study. Joule Work reporting study. Liu is the director of the Organic and Molecular Synthesis Facility at the Molecular Foundry, a facility used for the Department of Energy’s Office of Science at Berkeley Laboratory.
Advantages and challenges of condensation
In addition to remaining stable when exposed to high temperatures, a capacitor must be a strong “insulator,” meaning that it remains a strong insulator when exposed to high voltages. However, there are only a few known material systems that provide thermal stability and dielectric strength. This rarity is due to the lack of reliable and convenient manufacturing methods, as well as a lack of basic understanding of the relationship between polymer structure and properties. “Improving the thermal stability of existing films while maintaining their dielectric strength is an ongoing challenge for materials,” Liu said.
A long-standing collaboration between researchers at the Molecular Foundry Institute and the Scripps Research Institute has now overcome this challenge. They used a simple and rapid chemical reaction developed in 2014, which swaps fluorine atoms in compounds containing sulfur-fluoride bonds, to produce long polymer chains of sulfate molecules called polysulphates.
this Sulfur fluoride exchange reaction (SuFEx). It is a next-generation version of the click chemical reaction created by K. Barry Sharpless, a two-time Nobel Prize-winning Scripps Research chemist and Peng Wu, also a Scripps Research chemist. Near-perfect, easy-to-operate reactions join separate molecular entities through strong chemical bonds that form between different reaction groups. Liu’s team originally used a variety of thermal analysis tools to examine the basic thermal and mechanical properties of these new materials.
As part of the Berkeley Lab’s program to synthesize and identify new materials that could be useful in energy storage, Liu and his colleagues have now found that, surprisingly, polysulphates have outstanding insulating properties, especially at high electric fields and temperatures. “Many commercial and laboratory-produced polymers are known for their insulating properties, but polysulfates have never been taken into account. The marriage between polysulphates,” said He Li, a postdoctoral researcher in the Molecular Foundry in Berkeley Lab’s Department of Materials Science and lead author of the study. Insulating material is a novelty here.”
Capacitor performance and potential impact
Inspired by the excellent basic insulating properties provided by polysulfates, the researchers deposited ultra-thin layers of aluminum oxide (Al2Hey3) on thin films of the material to design capacitive devices with improved energy storage performance. They discovered that the manufactured capacitors showed excellent mechanical flexibility, withstanding electric fields of more than 750 million volts per metre, and performing efficiently at temperatures of up to 150 degrees. Celsius. By comparison, today’s standard commercial polymer capacitors only operate reliably at temperatures below 120°C. Above this temperature, it can only withstand electric fields smaller than 500 million volts per meter, and energy efficiency drops sharply by more than half.
This work opens up new possibilities for exploring robust, high-performance materials for energy storage. “We have provided deep insight into the underlying mechanisms that contribute to the excellent performance of the material,” Wu said.
The polymer achieves a balance of electrical, thermal, and mechanical properties, likely due to the sulfate bonds generated by the click reaction. Because modular chemistry accommodates extraordinary structural versatility and scalability, the same pathway can provide a viable pathway for new, higher-performance polymers that meet more demanding operating conditions.
These polysulphates are strong contenders to become modern polymeric insulators. Once scientists overcome hurdles in large-scale thin-material fabrication processes, the devices can dramatically improve the energy efficiency of integrated power systems in electric vehicles and enhance their operational reliability.
“Who would have imagined that a soft polymer layer of sulfate could repel lightning and fire, two of the most destructive forces in the universe?!” Sharpless expressed.
“We are constantly expanding the range of thermal and electrical properties, accelerating the process from lab to market,” Liu added.
Reference: “High-Performance Polysulphate Dielectrics for Electrostatic Energy Storage Under Harsh Conditions” by He Li, Boyce S. Chang, Hyunseok Kim, Zongliang Xie, Antoine Lainé, Le Ma, Tianlei Xu, Chongqing Yang, Junpyo Kwon, Steve W. Shelton. Liana M Klevansky, Virginia Alto, Bing Zhao, Adam M. Schwartzberg, Zongren Peng, Robert O. Richie, Ting Xu, Mikel Salmeron, Ricardo Ruiz, K. Barry Sharpless, Peng Wu and Yi Liu, January 18, 2023, Available here. Joule.
The work received funding from the Department of Energy’s Office of Science, the National Science Foundation, and the National Institute of Health. The work was carried out at the Molecular Foundry.