Ultralow Overpotential Photoassisted Li-N₂ Battery Enabled by Defective Cobalt Phosphide with High-Spin States

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Lithium-nitrogen (Li-N₂) batteries offer potential for energy storage and nitrogen fixation.
• Challenges include nitrogen's inertness and poor cathode activity, hindering practical use.

Purpose of the Study:

• To develop a novel photoelectrocatalytic cathode for enhanced Li-N₂ battery performance.
• To investigate the mechanism of nitrogen activation and reduction under illumination.

Main Methods:

• Engineered a defective cobalt phosphide (CoP_v) cathode with high-spin states and phosphorus vacancies.
• Utilized photoelectrocatalysis, leveraging light to enhance electron transfer and nitrogen activation.
• Analyzed the synergistic effects of vacancies and spin-polarized electrons on the nitrogen reduction reaction (NRR).

Main Results:

• Achieved a high discharge specific capacity of 2.71 mAh cm^-2.
• Demonstrated excellent cyclic stability of approximately 900 hours.
• Reported an ultralow overpotential of 1.3 V, the lowest reported to date.
• Observed significant nitrogen fixation facilitated by light.

Conclusions:

• The defective CoP_v photoelectrocatalytic cathode significantly enhances Li-N₂ battery performance.
• Light-assisted electron injection into N₂ via P vacancies is crucial for improved NRR kinetics.
• This approach offers a promising strategy for advancing Li-N₂ battery technology for energy storage.