Correlating Electronic Transition With Electrical Output to Reveal Photon‐Mediated Energy Conversion Mechanism in Inner‐Shell Electron Battery

ABSTRACT Inner‐shell electron batteries present a promising route to ultrahigh‐density energy storage by harnessing the potential energy confined within inner‐shell orbitals. While prior efforts have demonstrated the conversion of potential energy into electricity with photovoltaic (PV) modules, a direct correlation between inner‐shell electron transition and the resulting electrical output remains obscured by interfering photons. Here, by integrating systematic theoretical analysis of electron transition behaviors with a narrowband‐filter‐based experimental setup, we demonstrate a photon‐mediated energy‐conversion framework, exemplified by Mo 15+ (370.81 nm), Mo 16+ (370.85 nm), and La 19+ (371.96 nm) as highly charged ions (HCIs) selected near the peak efficiency wavelength of the PV module, which directly correlates specific electronic transition with power output. After filtering out unrelated wavelengths, we achieve a current response of 2.3 × 10 −12 C by capturing 7 × 10 7 photons emitted from 1 × 10 6 La 19+ ions. Furthermore, the replacement of the narrowband filter (365–375 nm) with an infrared filter to collect all emitted photons from HCIs yields an energy density of 1 × 10 4 Wh kg −1 based on the mass of 1 × 10 6 La 19+ ions, thereby holding great promise for future ultrahigh‐density energy storage applications.