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The research was developed at the Bioelectrochemistry and Interfaces Group of the São Carlos Institute of Chemistry (IQSC) at USP, with support from doctoral student Luana Italiano and postdoctoral researchers Graziela Sedenho and Rafael Colombo. “In 2014, at the California Institute of Technology (Caltech), I worked with endonucleases, which are enzymes that use highly reactive metals in their active sites. What caught my attention was the fact that these metals do not degrade because the protein creates an extremely well-controlled chemical microenvironment that precisely regulates coordination, solvent access, and electron transfer”, Crespilho says.

This perspective deepened later, in 2018, at Harvard University, where he worked with bioinspired quinones applied to redox batteries. “It became clear there that electrochemical reversibility depends not only on the material itself, but also on the molecular environment surrounding it. When we applied these concepts to niobium, we realized that the historical problem was never the metal itself, but rather the inadequate environment in which it was placed”, he adds.

“Rather than trying to ‘tame’ niobium by force, we created an artificial microenvironment inspired by biology. This environment is capable of cooperating with the metal, stabilizing its oxidation states, and enabling its reversible operation”, Crespilho highlights. “This principle was essential in developing the first niobium-based battery rather than a combination of niobium and other conventional chemicals”.

Crespilho explains that the device operates based on two complementary layers. “The first is the NB-RAM architecture, which forms a true ‘chemical protection box’ around the niobium. This architecture locally controls the metal’s chemical coordination, redox activity, and electronic availability, preventing uncontrolled oxidation”, he describes. “The second layer is what we call the N-MER, or the electronic-redox mechanism. It acts as a fine regulator, governing how electrons enter, are stored, and exit the niobium within this controlled environment, working as a fine regulator of electron flow”.

“In practice, this combination enables niobium to transition between its oxidation states in a staggered, reversible, and stable manner by exploiting multiple electrons of the same metal”, Crespilho notes. “This enables voltages on the order of 3 volts, which is unprecedented for systems based on niobium”.

According to Crespilho, the prototypes exhibited consistent performance across multiple charge and discharge cycles. They demonstrated high electrochemical reversibility and a potential window that was significantly higher than that predicted for niobium in traditional electrochemical systems. “These results validate the concept and establish niobium as a viable competitor in lithium-free energy storage technologies for the first time”.