Silicon-nanotube anode design promises boost in lithium-ion performance

Researchers at the University of Surrey in the UK have developed a new lithium-ion battery anode architecture containing carbon nanotubes that could significantly increase energy density while maintaining cycle life, potentially extending the range of electric vehicles and the lifespan of portable electronics.

“Many of today’s technologies are limited by how much energy batteries can store. Our VISiCNT design offers a practical route to harness silicon’s huge storage capability without sacrificing cycle life.”
Dr Muhammad Ahmad, research fellow © University of Surrey

The design, reported in ACS Applied Energy Materials, is built upon a “vertically integrated silicon-carbon nanotube” (VISiCNT) structure, which addresses one of the most persistent challenges in lithium-ion battery development: how to exploit silicon’s high storage capacity without compromising durability.

Silicon has long been considered a promising alternative to conventional graphite anodes due to its much higher theoretical capacity. However, it undergoes significant volumetric expansion during charging, leading to mechanical degradation, loss of electrical contact and rapid capacity fade.

Carbon nanotubes grown directly onto copper foil

The Surrey team’s approach uses dense arrays of carbon nanotubes grown directly onto copper foil, the current collector material already used in commercial lithium-ion cells. A thin silicon coating is then applied to this nanotube scaffold, creating a flexible, conductive structure capable of accommodating expansion during cycling.

According to the researchers, this architecture enables both high capacity and improved structural stability. Laboratory testing demonstrated specific capacities exceeding 3,500 mAh/g — close to silicon’s theoretical maximum and almost an order of magnitude higher than the ~370 mAh/g typically achieved with graphite anodes.

“We can grow carbon nanotube structures directly onto copper fo at speed and tailor the silicon layer for stability, meaning this approach could be integrated into existing battery productio lines with minimal disruption. The technology has clear potential not just for electric vehicles, but also for grid storag and smaller batteries used in microelectronics.”
Professor Ravi Silva
© University of Surrey

The system also showed improved cycling performance, maintaining stability over repeated charge–discharge cycles. This combination of high energy density and durability is seen as a key requirement for next-generation lithium-ion batteries, particularly in electric vehicles where both range and lifetime are critical.

The VISiCNT structure also offers potential manufacturing advantages. By growing carbon nanotubes directly onto copper foil, the process is compatible with existing battery production infrastructure and could be scaled using roll-to-roll manufacturing techniques. This may reduce barriers to commercial adoption compared with more disruptive battery chemistries.

The work reflects a broader industry focus on incremental improvements to lithium-ion technology, particularly through advanced electrode materials, as fully alternative chemistries such as solid-state batteries remain at an earlier stage of commercialisation.

The researchers suggest that the new design could support a wide range of applications, from electric vehicles to grid storage and consumer electronics. As demand for energy storage continues to grow, improvements in anode performance are seen as one of the most effective routes to increasing overall battery capability.