A Solar Battery with Light Assisted Discharge and Charge Interfaces

Abstract

Energy is the one of the decisive tool for survival of human civilization, which is harvested from various sources, among which fossil fuels occupy a larger space. The major problems which comes from the enormous use of fossil fuels are that they cause excessive pollution to air, water and land and increase the accumulation of greenhouse gases in the ecosystem, threatening the lives various flora and fauna thriving on this planet. In this context harvesting and storing solar energy by artificial photosynthesis and certain electrochemical reactions in batteries gain paramount importance. Latter technology requires two separate devices as a part of the solar energy harvesting architect, for eg, a solar cell to harvest light and a battery to store it, demanding complex engineering design with multiple interfaces. In this project the properties of batteries and solar cells are integrated in to a single device called “Solar Battery”, which in turn can harvest and store energy in the same device. The proposed battery consists of a titanium nitride (TiN) photoanode as the discharge component, Prussian blue analogue (PBA) electrode as battery active species and Mg doped–Fe2O3 (MgFeO) photocathode as the charge component. The result indicate that the battery can be cycled in ambient, visible and UV-vis light without the aid of any external power supply and the architectural components possess decent stability and cyclability. The advantage of the present architect is that both discharge and charge reactions are light assisted, considerably simplifying the discharge and charge chemistry from the kinetic limitations of active metal ions dissolution/ redeposition, dendrite formation and associated safety issues. The discharge mechanism is identified as O2 evolution at the photoanode with concomitant metal ion insertion at the PBA electrode. The charge chemistry involves the pumping of electrons from the reduced PBA to the photocathode with simultaneous H2 evolution at the semiconductor/electrolyte interface. As the charge reaction is light assisted, it resulted in charging the battery without any external bias, ultimately leading to a complete solar battery.