Aluminum-Anode Batteries Could Make Solar Energy Storage More Affordable

One of the challenges with capturing green solar energy is in being able to store that energy for use in times when the sun is unavailable. While the cost of harvesting solar energy has declined significantly in recent years, the cost to store that energy via battery packs and other methods hasn't come down as quickly. Researchers from Cornell have been exploring low-cost materials to create rechargeable batteries to make energy storage more affordable.The team believes their breakthrough could provide a safer and more environmentally friendly alternative to lithium-ion batteries dominating the battery market currently. Lithium-ion batteries do have some challenges, including that they are slow to charge and could catch fire if punctured or damaged. In their current research, scientists are using aluminum and zinc to create a new battery.

Researchers say one of the interesting features of their battery is that it has only two elements used for the anode and the cathode. Those elements are aluminum and carbon. Both are inexpensive and environmentally friendly. The batteries have a long lifecycle, and when the team calculated the cost of energy storage, the longer the life of the battery, the more significant the cost reduction for storage.

One of the major advantages of using aluminum is that it is an abundant material that has a high capacity for storing energy compared to many other metals. The challenge is that aluminum is difficult to integrate into a battery electrode. Aluminum reacts chemically with the glass fiber separator that physically divides the anode and cathode, leading to battery short-circuit and failure.

The Cornell researchers addressed that issue by designing a substrate of interwoven carbon fibers that form a stronger chemical bond with aluminum. As the battery charges, the aluminum is deposited into the carbon structure via covalent bonding. The technique does require nonplanar architecture for the battery and creates a deeper and more consistent layering of aluminum with the ability to be finely controlled. The researchers note that their aluminum-anode batteries can be reversibly charged and discharged one or more orders of magnitude more times than other aluminum rechargeable batteries under practical conditions.