In traditional batteries, the electrical energy, or current, flows as moving electrons. This current of electrons out of the battery is generated within the battery by moving positive ions. The ion current battery however moves electrons around in the device to deliver energy that is a flow of ions.
According to the researchers, this is the first time that an ionic current-generating battery has been invented.
"In a typical battery, electrons flow through wires to interface electronics, and ions flow through the battery separator,” said Professor Liangbing Hu. “In our reverse design, a traditional battery is electronically shorted so the electrons flow through the metal wires. The ions then have to flow through the outside ionic cables.
According to the team, potential applications include devices to micro-manipulate neuronal activities and interactions that can prevent and/or treat such medical problems as Alzheimer's disease and depression; medical devices for the disabled; more efficient drug and gene delivery tools; and direct machine and human communication.
"My intention is for ionic systems to interface with human systems," Prof Hu added.
To make the battery, the team soaked blades of Kentucky bluegrass in lithium salt solution. The channels that once moved nutrients up and down the grass blade were ideal conduits to store energy.
"The microchannels in the grass can hold the salt solution, making them a stable ionic conductor," said graduate student Chengwei Wang.
However, the team plans to diversify the types of ionic current electron batteries they can produce. "We are developing multiple ionic conductors with cellulose, hydrogels and polymers," said Wang.
