A new battery technology could be the end to lithium-ion and alkaline batteries. Stanford University scientists, have developed the first rechargeable aluminum-ion battery that's inexpensive, fast-charging and safe. “We have developed a rechargeable aluminum battery that may replace existing storage devices, such as alkaline batteries, which are bad for the environment, and lithium-ion batteries, which occasionally burst into flames,” said Hongjie Dai, a professor of chemistry at Stanford. “Our new battery won't catch fire, even if you drill through it.” A detailed article describing the new technology, “An ultrafast rechargeable aluminum-ion battery,” was published in the April 6 advance online edition of the journal, “Nature.” Aluminum has long been a desirable battery material, mainly because of its low cost, low flammability and high-charge storage capacity. For decades, researchers have tried unsuccessfully to develop a commercially viable aluminum-ion battery. A key challenge has been finding materials capable of producing sufficient voltage after repeated cycles of charging and discharging. To create an aluminum-ion battery, two electrodes are needed: a negatively charged anode made of aluminum and a positively charged cathode. Many different materials have been tried for the cathode. The Stanford scientists “accidentally” discovered that graphite material gives good performance as the cathode. For the experimental battery, the Stanford team placed the aluminum anode and graphite cathode, along with an ionic liquid electrolyte, inside a flexible polymer-coated pouch. The resulting battery generates about two volts of electricity. The Stanford team's battery has many benefits. In addition to being very safe, it's very durable. Early tests show that the battery can be recharged more than 7,500 times without any loss of capacity. By comparison, a typical lithium-ion battery lasts about 1,000 charge/discharge cycles. The battery is ultra-fast charging. The Stanford team reported “unprecedented charging times” of down to one minute with the aluminum prototype. The battery is also flexible, so it can be used in flexible electronic devices, and aluminum is cheaper and more environmentally friendly than lithium.
What's the downside? Right now the aluminum-ion battery only produces about half the voltage of a typical lithium battery. The Stanford researchers are working to improve the cathode material, which will hopefully increase the voltage and energy density. And while it is expected that the aluminum-ion battery would be a game changer for smartphones and tablet computers, such batteries could also be created in very large versions to store renewable energy on the electrical grid. The Stanford team's latest unpublished data suggests that aluminum-ion batteries can be recharged tens of thousands of times making investment in these very large grid batteries a viable proposition. Principal support for the aluminum-ion battery research was provided by the US Department of Energy, the Taiwan Industrial Technology Research Institute, the Stanford Global Climate and Energy Project, the Stanford Precourt Institute for Energy and the Taiwan Ministry of Education.
