Materials to build aluminium batteries

May 1, 2018 | 13:55
Aluminium... its light, cheap and abundant
Aluminium... its light, cheap and abundant
Scientists in Switzerland working at the ETH in Zurich and Empa have identified two important materials suitable for use in aluminium battery design. The first is titanium nitride, a corrosion-resistant material for conductive parts of the battery; the second is polypyrene, a novel material for the positive battery electrode.

Titanium nitride
Unlike lithium, aluminum is the most abundant metallic material in the Earth’s crust. It is easy to mine and therefore inexpensive. Unfortunately, the electrolyte required to make an aluminum battery is extremely corrosive and attacks stainless steel, gold and platinum. A search has been underway to find suitable materials with the right properties and the ability to survive prolonged contact with the electrolyte. The latest find is titanium nitride (TiN) which is an extremely hard ceramic material, often used as a coating on titanium alloys, steel, carbide, and aluminium components to improve the substrate's surface properties. Both Titanium and Nitrogen are readily available and TiN is easy to produce.

TiN can easily be made as a thin film and is useful as a coating on other materials such as polymer films. TiN may also be useful in the construction of magnesium or sodium batteries and even lithium-ion batteries.

Polypyrene is the second important material identified for use as the positive electrode in the new aluminium battery design. The negative electrode is made of aluminium and graphite is commonly used for the positive electrode. Polypyrene is a polymer of polycyclic hydrocarbons and rivals graphite for its energy storage properties.  In tests, samples of polypyrene produced good results and space in its molecular chains allows the relatively large ions of the electrolyte to easily penetrate the electrode material.
One advantage of a polypyrene electrode is the ability to control of the material porosity which can be optimised for specific applications.

Titanium nitride can be applied to base materials such as plastics to provide some flexibility. The use of large capacity batteries acting as energy storage buffers for intermittent green energy generators is becoming an ever more important application, fuelling research into low-cost high-performance batteries.

Source: ETH Zurich
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