Salt-based battery offers promising cheap energy storage for renewables
A rechargeable battery made using salt promises to last longer than conventional batteries, while storing more power.
Growing demand for electric vehicles and more sustainable forms of transport means that the hunt is on to find new forms of energy storage that offer better performance than current lithium-ion batteries.
According to the researchers, the new design merges the merits of a solid-oxide fuel cell and molten metal-air battery, while offering significantly improved battery reaction kinetics and power capability without compromising the energy capacity.
Professor George Chen, who led the research team, said: “Currently, the major challenge to rechargeable metal-oxygen batteries resides in the sluggish kinetics of electrode reactions, resulting in low energy and power densities. Therefore, activation of the reactions of both the negative and positive electrodes is crucial for high-performance, rechargeable, metal-oxygen batteries.”
The team were able to elevate the working temperature of a metal-oxygen battery using iron as a base, which can be activated at a high temperature while keeping the cost low.
However, the technology is prone to forming metal oxides between the metal and solid electrolyte which impedes the ion conductivity and the effectiveness of the battery.
“One type of high-temperature metal-oxygen battery is the so-called molten air battery, which can use base metals for fast multiple-electron charge transfer in molten salts,” said Dr Cheng Peng, first author of the paper.
“The molten salts have the capability to dissolve metal oxides. Our proposal looked at a molten salt iron-oxygen battery with a bi-phase electrolyte of molten carbonate and solid oxide which merges the merits of both types of battery.
“The result was a low-cost and long service life rechargeable high-temperature molten salt iron-oxygen battery with both high energy storage capacity and fast charging and discharging power capability.”
The team anticipates that the new battery has a great potential application in the area of grid-scale and renewable energy storage.
The research behind the battery design also has multiple possible applications. For example, the researchers state that the molten salts are the ideal storage fluid for solar heat at high temperatures.
Therefore, the molten salt iron-oxygen battery could be capable of storing both solar heat and electricity in a solar energy scenario.