100x boost for rechargeable aluminium battery

100x boost for rechargeable aluminium battery

Technology News |
By Nick Flaherty

Researchers in the US have taken a key step forward to using aluminium for rechargeable batteries that are significantly higher capacity than today’s lithium ion cells.

A team at Cornell University led by Prof Lynden Archer has been exploring the use of low-cost materials to create rechargeable batteries that will make energy storage more affordable. The team has used carbon fibres to coat aluminium to improve the performance with over 10,000 cycles and 3,600 hours. This approach yields over 100 times the fundamental capacity of a battery cell

The paper, “Regulating Electrodeposition Morphology in High-Capacity Aluminium and Zinc Battery Anodes Using Interfacial Metal–Substrate Bonding,” was published in Nature Energy.

“A very interesting feature of this battery is that only two elements are used for the anode and the cathode – aluminium and carbon – both of which are inexpensive and environmentally friendly,” said Dr Jingxu (Kent) Zheng, now a postdoctoral researcher at the Massachusetts Institute of Technology.

“They also have a very long cycle life. When we calculate the cost of energy storage, we need to amortize it over the overall energy throughput, meaning that the battery is rechargeable, so we can use it many, many times. So if we have a longer service life, then this cost will be further reduced,” said Zheng.

Aluminium is abundant and low cost, with a high capacity to store more energy than many other metals. However, aluminium can be tricky to integrate into a battery’s electrodes as it reacts chemically with the glass fibre separator, causing the battery to short circuit and fail.

Using a substrate of interwoven carbon fibres instead forms an even stronger chemical bond with aluminium. When the battery is charged, the aluminium is deposited into the carbon structure via covalent bonding, the sharing of electron pairs between the aluminium and carbon atoms.

This is also a 3D non-planar architecture that creates a deeper, more consistent layering of aluminum that can be finely controlled.

“Basically we use a chemical driving force to promote a uniform deposition of aluminium into the pores of the architecture,” said Zheng. “The electrode is much thicker and it has much faster kinetics.”

The aluminium-anode batteries can be reversibly charged and discharged one or more orders of magnitude more times than other aluminium rechargeable batteries under practical conditions says Zheng.

“Although superficially different from our earlier innovations for stabilizing zinc and lithium metal electrodes in batteries, the principle is the same – design substrates that provide a large thermodynamic driving force that promotes nucleation; and runaway, unsafe growth of the metal electrode is prevented by forces such as surface tension that can be massive at small scales,” said Prof Archer.

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