Silicon offers double the battery life, lab says

by David Legard

March 7, 2003 —

Adding a controlled amount of silicon to the graphite normally used in the anode of a lithium-ion battery may double the energy storage capacity of that battery, researchers at the U.S. Department of Energy's Sandia National Laboratories said Thursday.

If the advance can be commercialized, it will lead to rechargeable lithium-ion batteries with more power, longer life and smaller size, the researchers said in a statement.

The anode, or electrically negative part of the battery, has traditionally been made of graphite to complement the lithium cathode, or positive part. Although silicon offers more than 10 times the charge capacity of graphite, it suffers rapid capacity loss during the discharging and recharging cycle.

The researchers have found that by adding small particles of silicon into a graphite matrix, the large battery capacities can be maintained. The new silicon/graphite anode combines large capacity with better capacity retention during cycling than other high-capacity materials. Designers also have the ability to control the anode's performance by changing the composition and microstructure of the graphite/silicon mix, according to the researchers.

The graphite/silicon anode can be produced by conventional milling techniques and uses abundant and cheap raw materials, Sandia said.

Battery life is an important consideration for makers of mobile devices such as laptop computers, PDAs (personal digital assistants) and cell phones. Designers need to balance the power of the device with the time it can keep running on a single battery charge.

Sandia is looking for partners to help with commercializing the new technology, the organization said in its statement

IDG News Service