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, according to researchers at the US Department of Energy's Sandia National Laboratories.
If the advance could be commercialised, it would lead to rechargeable lithium-ion batteries with more power, longer life and smaller size, the researchers said.
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.
The graphite/silicon anode could be produced by conventional milling techniques and used abundant and cheap raw materials, Sandia said.
Battery life was 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 commercialising the new technology.