Nanoscale Water Films hold the Key for Future Energy Storage and Transfer

High temperature energy storage solutions. Image source: PennState Research institute

In an interesting study carried out at North Carolina State University, scientists have found out a simple solution for energy storage and transfer: Just add nanoscale water.

A PhD student, James Mitchell, and a team headed by Prof. Veronica Augustyn demonstrated that materials containing a thin layer of water molecules were able to store and deliver energy in a much more efficient way.

This is a proof of concept, but the idea of using water or other solvents to ‘tune’ the transport of ions in a layered material is very exciting,” explains Augustyn.

The fundamental idea is that this could allow an increased amount of energy to be stored per unit of volume, faster diffusion of ions through the material, and faster charge transfer,” Augustyn goes on to explain.

NANOSCALE WATER BOOSTS ENERGY STORAGE

These layers of water molecules were in the nanoscale range, which is simple known as nanoscale water. These were used specifically to aid the storage and delivery of energy. In this case, it was crystalline tungsten oxides used for the comparison.

Regular tungsten oxide has the formula WO3 and is anhydrous, which means it doesn’t contain any water. The hydrated form is WO3.2H2O. The only difference between these two compounds is the thin layer of water molecules in the hydrated form.

Nanoscale water layers. Image source: North Carolina State University
Scaled image of the crystalline tungsten oxide hydrate. Image source: North Carolina State University

Both of the tungsten compounds had the same tests carried out.

The research found that the charging time significantly affects which form of the tungsten oxide stores the most energy. When the two materials were charged for 10 minutes, the regular tungsten oxide without the water molecules stored the most energy.

However, when the charging time was only 12 seconds, the hydrated form stored more energy than the regular tungsten oxide compound.

In essence, this means that the anhydrous form acts like a battery, whereas the hydrated form acts like a pseudocapacitor.

PSEUDOCAPACITORS- WELCOME TO FUTURE

Pseudocapacitance is what this field of research is known as – the storage of charge chemically through redox reactions as opposed to the physical storage of electrons.

Another noteworthy finding was that, unlike the anhydrous tungsten, the hydrated form was almost 100% efficient.

The goal for many energy-storage researchers is to create technologies that have the high energy density of batteries and the high power of capacitors,” says Mitchell. “Pseudocapacitors like the one we discuss in the paper may allow us to develop technologies that bridge that gap.”

As promising as this research is, it is still in its experimental stage and not ready to be applied commercially in the near future.

These findings have, however, prompted a positive response from the results obtained and give a potential pathway for these water molecule layers to be present in everyday batteries for personal goods.

Again, this is only a first step, but this line of investigation could ultimately lead to things like thinner batteries, faster storage for renewable-based power grids, or faster acceleration in electric vehicles,” says Augustyn.

We are now moving forward with National Science Foundation-funded work on how to fine-tune this so-called ‘interlayer,’ which will hopefully advance our understanding of these materials and get us closer to next-generation energy storage devices.”

Whilst this research may only be in its infancy, it all helps the ever growing need for the planet to use renewable sources of energy and cut down on CO2 emissions.

The research paper titled, “Transition from Battery to Pseudocapacitor Behavior via Structural Water in Tungsten Oxide,” is published in Chemistry of Materials Journal and can be read here

 

Source Chemistry of Materials Journal

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