New cell-inspired material eliminates need for metals, plastics in energy storage

Scientists at Northwestern University have developed a new liquid material that harvests, stores, and releases energy within a single system.
Powered by sources like light or electricity, the metal- and plastic-free material physically shape-shifts from a fluid into an energy-dense gel to store power, then resets to a liquid simply by exposure to open air.
This sustainable, adaptable platform eliminates the need for hardware components, opening new doors for clean energy and soft electronics.
“Our material’s ability to store and release energy on demand could make it useful for energy storage, environmental remediation and next-generation soft electronics,” said Samuel I. Stupp, the study’s senior author.

Bio-inspired technique
To build it, the team looked inside our own bodies and drew inspiration from the cell’s cytoskeleton.
A cellular skeleton is incredibly dynamic. It constantly constructs, breaks down, and reconstructs itself to help the cell move and divide.
Northwestern researchers designed a material that physically builds, dismantles, and rebuilds itself to manage energy.
Powered by external electrons from sources such as sunlight or X-rays, the initial yellow liquid transforms into an energy-rich black gel that can store energy for months and drive chemical reactions.
The entire process resets seamlessly when exposed to open air, which dissolves the gel back into its liquid state, allowing it to be recharged and reused repeatedly.
“Living systems are remarkably dynamic,” Stupp said. “They constantly build structures, break them apart, and rebuild them. We wanted to create a synthetic material that behaves in a similar way while performing useful functions.”
To overcome the limitation where energy harvesting, storage, and usage require separate devices, researchers used supramolecular materials that self-organize into larger networks.
A custom molecule, ANI-MV, was designed. It integrates two functional components into a single system: an amino naphthalene aromatic unit (ANI) that responds to light, and a methyl viologen (MV) unit that stores the captured electrons.
Use in soft electronics
When the light-responsive ANI portion absorbs energy, it transfers electrons to the MV portion, causing neighboring molecules to strongly attract and form pairs called pimers.
These pimers organize into semiconducting nanoscale ribbons with free-moving, delocalized electrons that eventually entangle into a black gel.
This network stores electrons throughout its structure, marking the first real-world example of a supramolecular polymeric pimer built from electron-storing molecular pairs.
In laboratory experiments, researchers demonstrated the material’s remarkable versatility by triggering its transformation from a yellow liquid into an energy-rich, conductive black gel using chemical fuel, light, electricity, or X-rays.
As light can selectively target the fluid, scientists were able to print microscopic conductive patterns that completely vanish once exposed to open air, which reverts the gel back into non-conductive liquid clusters.
Furthermore, this stored energy can be transferred to oxygen, generating highly reactive molecules that enable the gel to power chemical reactions in complete darkness. This process is known as dark photocatalysis.
“Most light-driven materials stop working when the light source is gone,” Stupp said. “Our material enables a form of ‘dark photocatalysis.'”
Researchers envision this material powering applications ranging from environmental remediation and clean energy to adaptive soft electronics.
The study was published in the journal Chem on June 11.

