Higher Capacity, Faster Charges for Lithium-Ion Batteries

Lithium-ion batteries are at the heart of most rechargeable electronics, from cell phones to iPods to the electric motorcycle we told you about the other day, but their energy capacity and charge times have always been limited by the basic physics of lithium ions. Researchers at Northwestern University have developed an electrode for li-ion batteries that could allow them to hold a charge 10 times longer, and research 10 times faster than current batteries.

Conceivably, this development could also help design engineers create smaller, more efficient batteries for electric vehicles and electronics. A paper describing the research was published in Advanced Energy Materials. Lead author Harold Kung is a professor of chemical and biological engineering at the McCormick School of Engineering and Applied Science.

“We have found a way to extend a new lithium-ion battery’s charge life by 10 times. Even after 150 charges, which would be one year or more of operation, the battery is still five times more effective than lithium-ion batteries on the market today.”
— Harold Kung, Northwestern University.

Li-ion batteries charge via a chemical reaction that sends the ions between the anode and cathode of the battery. Battery charge is limited by how many lithium ions can be packed into either end of the battery, while the charge rate is limited by the speed at which the ions travel from the electrolyte to the anode.

To increase capacity, Kung’s team sandwiched clusters of silicon between the graphene sheets in the anode to allow for a greater number of lithium atoms. The researchers also used a chemical oxidation process to create tiny holes (10 to 20 nanometers) in the graphene sheets so that the ions would not have to travel as far into the anode, reducing charge times significantly.

Source: Northwestern University

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