Teh iPhone 17 Air Could Use a silicon-Carbon Battery. What Is It?
Rumors suggest the upcoming iPhone 17 Air may feature a next-generation battery technology utilizing silicon-carbon anodes, perhaps contributing to a projected price increase to around $1,099 – a $200 jump from the expected iPhone 16 Plus. But what exactly is a silicon-carbon battery, and what advantages does it offer?
The core challenge with using silicon in batteries lies in its tendency to expand significantly when “lithiated” – the process of absorbing lithium ions during charging. This expansion, up to three times the original volume, can lead to battery swelling and ultimately, safety risks, a problem familiar even to users of conventional lithium-ion batteries.
Companies like Group14 are tackling this issue by combining silicon with carbon in a unique way. According to Rick Luebbe of Group14, their approach begins with a highly porous carbon material. “Imagine a carbon sponge, but the pores of that sponge are on the single-digit molecule wide, we’re talking less than 10 nanometers wide,” he explains. These microscopic pores are then filled with silane gas (the silicon source), but only partially – leaving significant void space within the material.
This design is key to managing the expansion. As lithium ions move to the anode during charging and the silicon lithiates, it expands into the pre-existing void spaces. “It mitigates the expansion at the particle level, so the battery doesn’t see the expansion, so it stabilizes the battery, and you get excellent cycle life,” Luebbe says. “That’s the critical insight in the invention: really learning how to internalize that expansion, so that it’s insulated from the battery chemistry and mechanical operations.”
while silicon is poised to become a standard component in future lithium-ion batteries, challenges remain. Vincent Chevrier, a researcher in the silicon field for 15 years and a partner at battery consulting firm Cyclikal, points to cost as a major hurdle. Group14’s use of silane gas, while yielding superior performance, can be up to ten times more expensive than using solid silicon. This increased material cost could translate to higher prices for consumer electronics.
Chevrier also cautions against inflated energy density claims frequently enough made by silicon-carbon manufacturers. Group14 states its silicon batteries can deliver up to 50 percent more energy density than conventional lithium-ion batteries. However,Chevrier notes that simply replacing graphite with a silicon-carbon anode without further cell redesign typically results in a more modest 10 percent increase. A full battery redesign leveraging the material could potentially achieve up to a 30 percent increase in energy density.
