Tag Archives: University of Maryland

New Cathode Triples the Energy Storage of Lithium-Ion Batteries

As the demand for smartphones, electric vehicles, and renewable energy continues to rise, scientists are searching for ways to improve lithium-ion batteries—the most common type of battery found in home electronics and a promising solution for grid-scale energy storage. Increasing the energy density of lithium-ion batteries could facilitate the development of advanced technologies with long-lasting batteries, as well as the widespread use of wind and solar energy. Now, researchers have made significant progress toward achieving that goal. A collaboration led by scientists at the University of Maryland (UMD), the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, and the U.S. Army Research Lab have developed and studied a new cathode material that could triple the energy density of lithium-ion battery electrodes

Lithium-ion batteries consist of an anode and a cathode,” said Xiulin Fan, a scientist at UMD and one of the lead authors of the paper. “Compared to the large capacity of the commercial graphite anodes used in lithium-ion batteries, the capacity of the cathodes is far more limited. Cathode materials are always the bottleneck for further improving the energy density of lithium-ion batteries.

Scientists at UMD synthesized a new cathode material, a modified and engineered form of iron trifluoride (FeF3), which is composed of cost-effective and environmentally benign elements—iron and fluorine. Researchers have been interested in using chemical compounds like FeF3 in lithium-ion batteries because they offer inherently higher capacities than traditional cathode materials.

The materials normally used in lithium-ion batteries are based on intercalation chemistry,” said Enyuan Hu, a chemist at Brookhaven and one of the lead authors of the paper. “This type of chemical reaction is very efficient; however, it only transfers a single electron, so the cathode capacity is limited. Some compounds like FeF3 are capable of transferring multiple electrons through a more complex reaction mechanism, called a conversion reaction.

The findings are published in Nature Communications.

Source: https://www.bnl.gov/

Adaptive Materials

Engineers at the U.S. Army Research Laboratory (ARL) and the University of Maryland have developed a technique that causes a composite material to become stiffer and stronger on-demand when exposed to ultraviolet light. This on-demand control of composite behavior could enable a variety of new capabilities for future Army rotorcraft design, performance and maintenance.

ARL‘s Dr. Frank Gardea, a research engineer, said the focus of the research was on controlling how molecules interact with each other. He said the aim was to “have them interact in such a way that changes at a small size, or nanoscale, could lead to observed changes at a larger size, or macroscale.”

Dr. Bryan Glaz, chief scientist of ARL‘s Vehicle Technology Directorate said “an important motivation for this work is the desire to engineer new structures, starting from the nanoscale, to enable advanced rotorcraft concepts that have been proposed in the past, but were infeasible due to limitations in current composites. One of the most important capabilities envisioned by these concepts is a significantly reduced maintenance burden due to compromises we make to fly at high speeds”, he said. The reduced scheduled maintenance of future Army aviation platforms is an important technological driver for future operating concepts.

Army researchers imagine a rotorcraft concept, which represents reactive reinforcements that when exposed to ultraviolet light will increase the mechanical behavior on-demand. The engineers said control of mechanical behavior could potentially lead to increased aerodynamic stability in rotorcraft structures.

The enhanced mechanical properties with potentially low weight penalties, enabled by the new technique, could lead to nanocomposite based structures that would enable rotorcraft concepts that we cannot build today,” Glaz said.

The joint work, recently published in Advanced Materials Interfaces (DOI: 10.1002/admi.201800038), shows that these composite materials could become 93-percent stiffer and 35-percent stronger after a five minute exposure to ultraviolet light. The technique consists of attaching ultraviolet light reactive molecules to reinforcing agents like carbon nanotubes. These reactive reinforcing agents are then embedded in a polymer. Upon ultraviolet light exposure, a chemical reaction occurs such that the interaction between the reinforcing agents and the polymer increases, thus making the material stiffer and stronger.

ource: https://www.arl.army.mil/