Cornell University scientists have developed a new aluminum anode that offers no less than 10,000 error-free charging cycles.
The team led by professor Lynden Archer had previously demonstrated the potential of zinc-anode batteries. They say aluminum is not only safer and eco-friendly, but also more affordable than our slow charging – and at times fire catching – lithium-ion batteries.
“A very interesting feature of this battery is that only two elements are used for the anode and the cathode – aluminum and carbon – both of which are inexpensive and environmentally friendly,” notes first author Jingxu Zheng.
“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.”
Aluminum is found abundantly in the earth’s crust. It is trivalent and light, and it therefore has a high capacity to store more energy than many other metals.
The one drawback with aluminum is that it can be tricky to integrate into a battery’s electrodes.
It reacts chemically with the glass fiber separator, which physically divides the anode and the cathode, causing the battery to short circuit and fail.
The Cornell team has found a way to overcome this by designing a substrate of interwoven carbon fibers that forms an even stronger chemical bond with aluminum.
When the battery is charged, the aluminum is deposited into the carbon structure via covalent bonding, i.e., the sharing of electron pairs between aluminum and carbon atoms.
While electrodes in conventional rechargeable batteries are only two dimensional, this technique uses a 3D or nonplanar – 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 aluminum into the pores of the architecture,” explains Zheng. “The electrode is much thicker and it has much faster kinetics.”
What’s more, the aluminum-anode batteries can further be reversibly charged and discharged one or more orders of magnitude more times than other aluminum rechargeable batteries under practical conditions.
Image and content: Cornell University