Photo-Rechargeable Sodium-Ion Batteries with a Two-Dimensional MoSe₂ Crystal Cathode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Integrating energy harvesting and storage in a single device is crucial for continuous power in diverse applications.
• Photovoltaic and electrochemical energy conversion often require separate systems, limiting efficiency and portability.

Purpose of the Study:

• To demonstrate a photochargeable sodium-ion battery (PSIB) utilizing a photoactive cathode for light-driven charging.
• To investigate the performance enhancement of a sodium-ion battery cathode under illumination.

Main Methods:

• Fabrication of a photoactive cathode using two-dimensional molybdenum diselenide (MoSe2) crystals.
• Galvanostatic cycling of the photochargeable sodium-ion battery under both dark and illuminated conditions.
• Analysis of charge transfer kinetics and ion diffusion mechanisms influenced by light exposure.

Main Results:

• The MoSe2 photocathode enabled spontaneous, photodriven charging of the sodium-ion battery.
• A 29% increase in reversible capacity was observed at 600 mA g-1 under illumination compared to dark conditions.
• The PSIB achieved a voltage of 1.68 V under light without external current, driven by photogenerated holes facilitating Na+ extraction and improved kinetics.

Conclusions:

• The developed photochargeable sodium-ion battery demonstrates a viable approach for light-driven rechargeable energy storage.
• This technology offers a pathway for self-charging batteries, benefiting off-grid applications like the Internet of Things.
• The use of MoSe2 as a photocathode significantly enhances battery performance through light-induced charge dynamics.