Fully Solar‐Powered Uninterrupted Highway Tunnel‐Lighting System Enabled by Cement‐Based Aqueous Ni‐Zn Structural Batteries

Highway tunnel lighting working 24 h a day, 365 days a year largely enables traffic safety but consumes a large amount of electric energy. Moreover, these tunnel lighting installations are powered by lithium-based batteries, which rely on Li sources and flammable organic electrolytes, leading to safety and space issues, or by electric power grids facing geographic limitations and high operating costs. Thus, taking advantage of cement-based materials to create low-cost and high-safety aqueous structural batteries and further develop a self-driven tunnel-lighting system is greatly desirable. Herein, the cement-based aqueous Ni-Zn structural batteries (CNZSBs), solar panels, and LEDs are successfully assembled together to realize a fully solar-powered uninterrupted lighting system, in which the CNZSBs can deliver a maximum energy density of 2.56 kWh m^-3, as well as enough compressive strength to act as part of the tunnel structure. Specifically, the solar panels featuring a sustainable energy input can enable the charging of CNZSBs for energy storage and provide stable energy for LEDs during the day, while the fully-charged CNZSBs offer a steady output voltage for lighting at night. Such an uninterrupted lighting system provides exciting opportunities for developing energy storage in building materials and exploiting renewable energy sources.