National Aeronautics and Space Administration (NASA) has been working on nano-electrofuel (NEF) flow batteries for electric aviation.
This means they could eventually power aircraft with non-explosive liquid rechargeable batteries.
The development of these flow batteries is being done by the Armstrong Flight Research Center's Aqueous Quick-Charging Battery Integration for Flight Research (Aquifer) within NASA. The aerospace company has always been innovative in the flow battery space — they invented a functioning flow battery back in the 1970s.
NASA says the flow batteries they are developing will have a higher energy density than solid lithium-ion batteries. However, there is a debate as to whether liquid batteries are better than solid-state batteries, particularly when it comes to electric vehicles.
Liquid vs. solid-state
Lithium-ion batteries are made up of liquid electrolyte solutions that utilize an anode and cathode system. A solid-state electrolyte results in a smaller battery with a higher energy density, using a lithium metal anode.
In the electric vehicle industry, liquid-based lithium-ion technology is being called into question. This is a result of fires that have occurred due to the bigger battery banks and the flammable liquid within the cell. Consequently, the industry is starting to pay a lot more attention to solid-state technology.
Solid-state batteries would be less prone to leaking or bursting into flames. They are also considerably smaller than liquid-based batteries. Researchers are indicating that solid-state batteries with a lithium metal anode might enable electric vehicles to travel longer distances than they already do with liquid-based batteries.
However, it seems the car manufacturers are struggling to find a solid-state solution that works for them.
But some companies are going ahead with developing Vanadium Redox Flow batteries — an energy storage technology that organizations like NASA are looking into. The other benefit of the redox battery is that it can be recharged faster than a lithium-ion battery.
The Vanadium Redox Flow batteries are liquid batteries, but unlike normal liquid cells, the electrolytes are housed in tanks outside the cell. These cells work by pumping the liquid into a stack of cells, where the electromechanical reaction takes place and electricity is produced. And word on the street is that they are less explosive than traditional liquid batteries.
NASA Electrical Engineer, Kurt Papathakis told media:
“We have demonstrated multiple recharge cycles and seen minimum to zero degradation. Also, unlike Li-ion batteries, NEF does not pay a penalty in cycle life for charging above 80-percent capacity or discharging below 20 percent.”
Cobalt, lithium, and vanadium are subsequently the most in-demand elements seeing a global demand in the energy storage industry.
Taking to the skies
It's not only NASA that are looking to power electric aircraft in the sky...Rolls-Royce is too. The company plans to launch an all-electric aircraft in 2020. They are also eyeing a world speed record for the plane — the engineers are looking to design an electric plane that can reach a top of speed of more than 300mph. They’re calling it the ACCEL.
The current title holder is the Siemens Extra Aircraft 330LE. It currently boasts the world's most powerful electric motor in an aircraft. It is powered by battery packs and is a joint engineering venture with Extra Aircraft, Siemens, MT-Propeller, and Pipistrel. The company reckons that passenger flights in small electric flights could happen as soon as 2025.
Rolls-Royce is working alongside a company named Electroflight and YASA on their project.
The most important benefit of battery-powered aircraft will be that they emit zero emissions.
Matheu Parr, the ACCEL Project Manager for Rolls-Royce said:
“This plane will be powered by a state-of-the-art electrical system and the most powerful battery ever built for flight. In the year ahead, we’re going to demonstrate its abilities in demanding test environments before going for gold in 2020 from a landing strip on the Welsh coastline.”
“Introducing ACCEL.” Rolls-Royce, www.rolls-royce.com/media/our-stories/innovation/2018/introducing-accel.aspx.
Robinson, Isabelle. “Using Liquid Batteries for Electric Aircraft.” AZoCleantech.com, AZoCleantech.com, 18 Jan. 2019, www.azocleantech.com/article.aspx?ArticleID=843.