Physicists develop higher energy capacities in batteries

Avatar By Le Williams | 2 years ago

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Department of Physics have developed a controllable, electrochemical system that can store large amounts of energy in the space between atomically thin sheets of layered two-dimensional materials.

According to a research article published in Nature, Kwabena Bediako, a former postdoctoral fellow at SEAS, states, “We observed that by stacking sheets of different, atomically thin materials, we could engineer higher electrochemical capacities, improving the accumulation of charge in the hybrid material by more than tenfold.”

The researchers exploited a physical effect known as van der Waals forces, which are weak bonds between molecules based on the total number of atoms and proximity rather than direct chemical interactions.

By bonding materials with van der Waals forces, the researchers found that they could combine any two layered materials to create a new electrochemical environment in the “empty” space between the two layers.

The researchers stacked layers of boron nitride, graphene and molybdenum dichalcogenide (MoX2) and injected lithium ions between the layers. The graphene provided a low-resistance electronic pathway, which in turn enabled the layer of MoX2 to hold onto lithium ions more efficiently.

“Beyond energy storage, this method for manipulating and characterizing the electrochemical behavior of layered systems opens new pathways to control a large charge density in 2-D electronic and optoelectronic devices,” said Philip Kim, professor of physics and of applied physics at SEAS and senior author of the paper.

In conclusion, the research provides evidence that the more lithium ions a developer can squeeze into a space, the higher the capacity of the battery. The more readily the ions come out, the higher the voltage.