Scientists in Germany have just unveiled a new class of fiber-based silicon anodes that could significantly increase the energy density of lithium-ion (Li-ion) batteries by up to 250 percent.

The technology, developed at the Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW), has the potential to reshape battery performance for electric vehicles (EVs) consumer electronics and renewable energy storage.

Known as FACILE, the project also brings together regional partners including ISC Konstanz, Phoenix NonWoven GmbH & Co. KG and mechanical engineering firm centrotherm international AG.

"FACILE shows how industry and science in Baden-Württemberg can jointly cover the entire value chain for lithium-ion batteries, from material development to cell production," Markus Hölzle, PhD, ZSW managing board member, stated.

Reinventing Li-ion cells

Conventional lithium-ion cells typically use graphite for their anodes, the battery's negative electrode. But graphite, which is the crystalline form of carbon, can store only about 370 milliampere-hours (mAh) of lithium per gram.

This storage limit has long constrained how much energy today's batteries can hold. Silicon (Si), on the other hand, can theoretically hold up to 4,200 mAh per gram. This corresponds to more than 10 times the capacity of graphite.

With silicon and graphite costing roughly the same, silicon offers a promising solution to affordable, high-energy batteries. However, when silicon absorbs lithium, it expands up to 300 percent.

This expansion causes cracking, layer delamination and rapid battery failure. Over the past decade, researchers have tried nanostructures, thin films and composite blends, but scaling these approaches for mass production still poses a challenge.