Magnesium batteries

Past the main technical barriers in magnesium batteries

Scientists at the National Renewable Energy Laboratory (NREL) They have discovered a new approach for the development of a rechargeable battery in a non-aqueous metallic magnesium.

A document published in Nature Chemistry has described in detail as they have opened the way for a method to enable the reversible magnesium chemistry in the metal in the electrolytes based on non-corrosive carbonate and tested the concept in a prototype cell. The technology has potential advantages over lithium-ion batteries, in particular, a higher energy density, greater stability and lower costs.

The dominant technology of the lithium-ion battery is approaching the maximum amount of energy that can be stored per volume, so there is an urgent need to explore new types of battery that can provide more energy at a lower cost.

An electrochemical reaction feeds a battery while the ions flow through a liquid (electrolyte) the negative electrode (cathode) the positive electrode (anodo). For batteries that use lithium, the electrolyte is a saline solution containing lithium ions. Furthermore, it is important that the chemical reaction is reversible so that the battery can be recharged.

Magnesium batteries (Mg) theoretically they contain almost twice as much energy per volume of lithium-ion batteries. But research to date have encountered an obstacle: chemical reactions conventional electrolyte have created a barrier on the magnesium surface, which has prevented the recharge battery. The magnesium ions could flow in the reverse direction only through a highly corrosive liquid electrolyte, but this prevented the possibility of creating a commercial magnesium battery.

In an attempt to overcome these obstacles, the researchers developed interphase (a buffer layer) that protected the anode surface of magnesium. This protected anode showed significantly improved performance.

The adjacent illustrations show how the NREL scientists have solved a problem with the realization of a rechargeable battery to magnesium.

Scientists have assembled prototype cells to demonstrate the artificial interphase strength and have found promising results: the cell with protected anode has allowed results never demonstrated before. The cell with this protected anode has also provided more energy prototype without protection and continued to do so during repeated cycles. Furthermore, the group has demonstrated the rechargeability of the magnesium battery, which provides a way unprecedented.

In addition to being more readily available lithium, magnesium has other potential advantages. First of all, magnesium releases two electrons instead of one of lithium, making it possible to deliver almost twice the energy of lithium. Furthermore, magnesium batteries do not suffer the growth of dendrites, which are crystals that can cause short circuits and therefore dangerous overheating and even fires, making magnesium batteries potentially much safer than the lithium-ion battery.

The electrolyte, one of the three main parts of a battery, is responsible for the transfer of charged ions in a solid state battery. This creates an electric current when the other two parts of the battery, the anode and the cathode, They are connected in a circuit.

Most rechargeable batteries of smartphones, computers and other consumer electronic devices use a liquid electrolyte lithium-based.

The new material is made up of sodium, phosphorus, tin and sulfur and has a shape of tetragonal crystal. It has flaws or areas in which they would present some sodium atoms, tin and sulfur, and these allow you to transfer ions.

Since sodium is much more abundant than lithium, a battery to sodium ions would potentially much more economical to produce than a lithium-ion. The material would also be safe to use.

When heating liquid electrolytes, become inflamed or release much heat that could do damage.

A few months ago an announcement was reached by researchers at Toyota, which provided that among 20 magnesium years will be the "new lithium".

A long time ago I remembered reading about a magnesium battery, already functioning, realized and patented in Italy. An internet search confirms that what happened in 1997, thanks to two researchers at the University of Padua, Vito Noto and Maurizio Fauri (who now works at the University of Trento).

After twenty years it is always the starting point, housed in university laboratories still at the working prototype stage, but that, to be industrialized continues to require approximately one million euro investment, a ridiculous capital as waste we see every day, but it never materialized.

The battery history magnesium Di Noto and Fauri, It is a typical example of how difficult it is to innovate in Italy, but also of how the world of science and industry is far from meritocratic: sometimes to go forward are not the best.

Before the closing of the article I became aware of this latest gem coming from Taiwan:

Researchers at the National Cheng Kung University have demonstrated a 3D printing process to the laser to produce a rechargeable magnesium than Lithium can bring, according to the team, in smaller batteries, up to three times more efficient and above all, It can be produced in minutes instead of hours. "

Amilcare

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