Breathing Batteries: An Innovative Advance in Energy Storage

A group of researchers led by Professor Chen Wanhua from the Faculty of Physical Sciences and Technologies at Ningbo University, in collaboration with researchers from Ningbo University of Technology and Ningbo Institute of Technology, announced a breakthrough in materials for solid-state lithium-ion battery anodes. The team successfully developed a new silicon nanowire anode with a three-dimensional “breathing” structure inspired by natural breathing mechanisms, opening promising prospects for the development of high-performance solid-state lithium batteries with silicon anodes. Solid-state lithium-ion batteries are widely regarded by scientists and industry as the “ultimate goal” for next-generation battery technologies due to their enhanced safety, higher energy density, and superior cycling performance. Among potential anode materials for these advanced batteries, silicon stands out due to its exceptionally high theoretical capacity-ten times that of traditional commercial graphite anodes-and excellent chemical compatibility.

However, the practical use of silicon is severely limited by its drastic volume expansion, more than tripling in size during charge-discharge cycles. This expansion leads to significant mechanical stress, interface delamination, and rapid degradation of electrochemical performance.

“If we compare a lithium battery to a warehouse for storing energy, silicon is recognized as a ‘supercarrier’ with enormous storage potential,” explained Professor Chen Wanhua. “However, this ‘giant’ possesses an extremely unstable nature; when lithium ions are absorbed during charging, the volume of silicon dramatically increases more than threefold. With repeated charge-discharge cycles, silicon behaves like a continually inflating and deflating balloon, ultimately ‘deflating’ due to fatigue, leading to a sudden reduction in battery life.”

To address this crucial challenge, the research group developed an innovative solution allowing silicon to “breathe freely” within the rigid solid-state environment. Using plasma-enhanced chemical vapor deposition (PECVD) technology, they designed and fabricated a new three-dimensional columnar silicon architecture that integrates directly with the current collector. This design features a “biphasic” core-shell structure realized through a two-step PECVD process. “We moved away from traditional ‘silicon powder’ and instead made the silicon ‘stand’ like trees in a forest, intertwining to form a three-dimensional network on the current collector,” explained Professor Chen. “There are numerous voids between these nanowires, similar to installing countless ‘breathing valves’ within the battery. When lithium ions enter, the silicon nanowires can expand into these reserved spaces without destroying the surrounding electrolyte.”

Experimental results demonstrate that this columnar silicon anode possesses exceptional electrochemical properties and practicality. The engineered battery has shown the ability to continuously provide power even when bent or cut by scissors, showcasing remarkable mechanical strength and safety. The global interest in solid-state lithium-ion batteries is growing, with significant investments in silicon anode technology due to its potential to revolutionize energy storage systems, driving further research and development in this field. The race to create safer, more efficient batteries continues to intensify, with solutions like this breathing silicon architecture leading the charge.