Lithium batteries, which are used for everything from electronics to vehicles, take time to recharge, usually in the realm of hours. But researchers at University of Southern California have developed a new lithium-ion battery that can recharge within 10 minutes and hold three times the amount of energy as other batteries.
The research comes from Chongwu Zhou, professor at USC’s Viterbi School of Engineering. Last year, Zhou’s team experimented with porous silicon nano-wires that helped improve the performance of lithium-ion batteries.
Silicon (Si) has the highest known theoretical specific capacity (3,590 mAh/g for Li15Si4, and 4,200 mAh/g for Li22Si4) as a lithium-ion battery anode, and has attracted extensive interest in the past few years. However, its application is limited by poor cyclability and early capacity fading due to significant volume changes during lithiation and delithiation processes. In this work, we report a coaxial silicon/anodic titanium oxide/silicon (Si-ATO-Si) nanotube array structure grown on a titanium substrate demonstrating excellent electrochemical cyclability. The ATO nanotube scaffold used for Si deposition has many desirable features, such as a rough surface for enhanced Si adhesion, and direct contact with the Ti substrate working as current collector. More importantly, our ATO scaffold provides a rather unique advantage in that Si can be loaded on both the inner and outer surfaces, and an inner pore can be retained to provide room for Si volume expansion. This coaxial structure shows a capacity above 1,500 mAh/g after 100 cycles, with less than 0.05% decay per cycle. Simulations show that this improved performance can be attributed to the lower stress induced on Si layers upon lithiation/delithiation compared with some other recently reported Si-based nanostructures.
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