An efficient and stable solar flow battery enabled by a single-junction GaAs photoelectrode

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy Systems

Background:

• Solar intermittency necessitates efficient energy storage solutions.
• Solar flow batteries (SFBs) offer a promising approach to store and release solar energy on demand.
• Current SFBs often utilize complex multi-junction photoelectrodes, hindering practical application.

Purpose of the Study:

• To develop an efficient and stable integrated SFB using a practical single-junction photoelectrode.
• To achieve high solar-to-output electricity efficiency (SOEE) with a simplified SFB design.
• To demonstrate the long-term stability of the developed SFB system.

Main Methods:

• Fabrication of an integrated SFB utilizing a back-illuminated, single-junction gallium arsenide (GaAs) photoelectrode with an n-p-n sandwiched design.
• Computational simulation for rational potential matching and optimization of operating conditions.
• Incorporation of a titanium dioxide (TiO2) protection layer and robust redox couples in a neutral pH electrolyte.

Main Results:

• Achieved a record SOEE of 15.4% for single-junction SFB devices.
• Demonstrated stable cycling performance over 408 hours (150 cycles).
• Validated the use of practical solar cells with higher photocurrent densities and lower photovoltages in SFBs.

Conclusions:

• The developed GaAs-based SFB offers a practical and efficient solution for solar energy storage.
• The n-p-n sandwiched design and protective TiO2 layer contribute to high performance and stability.
• This work advances the development of practical and high-performance SFBs for addressing solar intermittency.