A New View of Battery Technology

Wednesday, October 23, 2019

Scientists at Lawrence Berkeley National Lab (Berkeley Lab) have developed a new infrared approach to probing the first few molecular layers of a liquid in contact with a graphene electrode under operating conditions.

The research, conducted at the Advanced Light Source (ALS), offers a new way to study the interfaces that are key to understanding batteries, corrosion, and other bio- and electrochemical phenomena.

Infrared (IR) light is focused onto the sharp metallic tip of an atomic force microscope (AFM), enabling the acquisition of vibrational spectra from a graphene–liquid interface. Since the enhancement of the IR around the AFM tip decays exponentially with distance, with a decay length on the order of the tip radius, the resulting spectra should be sensitive to the layers of water within the decay length, which includes the first few molecular layers.

Solid–liquid interfaces are vital to physical and chemical processes in many subjects, including corrosion, the generation and storage of energy (fuel cells, batteries), biology (ion transport through cell membranes), and environmental science (chemical weathering). However, solid–liquid interfaces are difficult to experiment on because they are buried under the bulk of the materials on either side of the interface. Furthermore, the interface region is extremely thin—only a few atomic layers. Many techniques for probing materials reveal just surface information, or, if they can penetrate more deeply, provide information averaged over a large volume, rather than from a thin slice close to an interface.

Now, researchers have demonstrated a way to overcome these challenges, using synchrotron infrared nanospectroscopy (SINS) at the ALS to collect infrared vibrational spectra at a graphene–electrolyte interface with nanoscale spatial resolution. The technique paves the way for nondestructive, in situ, and operando investigations of liquid environments and solid–liquid interfaces, particularly for applications in biology, energy storage and electrochemistry.

Read more about the research here: als.lbl.gov/infrared-nanospectroscopy-at-graphene-liquid-interfaces/