University of Surrey researchers have developed a silicon–carbon nanotube battery anode that stored more than 3,500 mAh/g in laboratory tests — nearly ten times the capacity of conventional graphite. The VISiCNT structure grows carbon nanotubes directly onto copper foil, offering a potentially scalable route to higher-energy lithium-ion cells for EVs.
Researchers at the University of Surrey have developed a lithium-ion battery anode using silicon and carbon nanotubes that achieved more than 3,500 milliampere-hours per gram in laboratory tests — close to the theoretical maximum for silicon and roughly ten times the capacity of graphite anodes used in current batteries.
The work, published in ACS Applied Energy Materials, introduces a structure the team calls Vertically Integrated Silicon–Carbon Nanotube (VISiCNT). Dense forests of carbon nanotubes are grown directly onto copper foil, then coated with a thin layer of silicon. The resulting scaffold is flexible and conductive, designed to absorb the expansion that normally causes silicon anodes to crack and degrade during charging.
“There’s been a growing push for battery innovation, as many of today’s technologies are limited by how much energy batteries can store,” says Dr Muhammad Ahmad, research fellow at the university’s Advanced Technology Institute (ATI) and lead author of the study. “Our VISiCNT design offers a practical route to harness silicon’s huge storage capability without sacrificing cycle life.”
Silicon can store far more energy than graphite, the standard anode material in commercial lithium-ion cells, which has a capacity of around 370 mAh/g. However, silicon expands substantially during charging, leading to mechanical failure over time. The VISiCNT structure is intended to address this trade-off, and the team reports improved stability over hundreds of charge cycles in testing.
Ahmad adds that the design delivers “very high capacity, fast charging and long-term durability, while bringing us closer to batteries that can power electric vehicles and everyday devices for much longer on a single charge.”
A further consideration for commercialization is that the carbon nanotubes are grown directly onto copper — a material already standard in battery manufacturing — using what the team describes as a scalable process.
“We can grow carbon nanotube structures directly onto copper foil at speed and tailor the silicon layer for stability, meaning this approach could be integrated into existing battery production lines with minimal disruption,” says Professor Ravi Silva, principal investigator and director of the ATI. “The technology has clear potential not just for electric vehicles, but also for grid storage and smaller batteries used in microelectronics.”
Silva notes that the VISiCNT work follows earlier ATI carbon nanotube research that led to Vantablack, commercialized through university spin-out Surrey NanoSystems.
The study was funded by UKRI.
