Novel electrodes improve lithium-ion batteries

Writing in Nature Communications, the scientists describe a new technique for producing low-cost, silicon-based batteries with potential applications for a wide range of electrical devices.

‘Developing rechargeable lithium-ion batteries with high energy density and long cycle life is of critical importance to address the ever-increasing energy storage needs for portable electronics, electric vehicles and other technologies,’ said study co-author Zhenan Bao, a professor of chemical engineering at Stanford.

To find a practical, inexpensive material that increases the storage capacity of lithium-ion batteries, Bao and her Stanford colleagues turned to silicon.

‘We’ve been trying to develop silicon-based electrodes for high-capacity lithium-ion batteries for several years,’ said study co-author Yi Cui, an associate professor of materials science and engineering at Stanford. ‘Silicon has 10 times the charge storage capacity of carbon, the conventional material used in lithium-ion electrodes. The problem is that silicon expands and breaks.’

Studies have shown that silicon particles can undergo a 400-per cent volume expansion when combined with lithium. When the battery is charged or discharged, the bloated particles tend to fracture and lose electrical contact. To overcome these technical constraints, the Stanford team used a fabrication technique called in situ synthesis polymerization that coats the silicon nanoparticles within the conducting hydrogel.