Copper-Ion-Mediated Selenium Electrochemistry Enables 3.5 V Selenium Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Selenium (Se) offers high theoretical capacity for rechargeable batteries but suffers from low operating voltages and polyselenide shuttling in conventional alkali metal-ion systems.
• Existing selenium-based batteries exhibit sluggish kinetics and low discharge voltages (<2.1 V), limiting their practical application.

Purpose of the Study:

• To develop a nonaqueous electrolyte system for copper-ion-mediated selenium electrochemistry.
• To enhance the performance of selenium-based batteries by increasing operating voltage and suppressing polyselenide shuttling.

Main Methods:

• Investigated copper-ion-mediated selenium conversion in a novel Cu(ClO4)2/carbonate nonaqueous electrolyte.
• Analyzed the formation of insoluble and conductive CuxSe intermediates.
• Fabricated and tested a hybrid lithium-selenium battery utilizing the developed electrolyte.

Main Results:

• Successfully enabled reversible copper-ion-mediated Se conversion in nonaqueous electrolytes.
• Identified copper-ion mediation as a strategy to produce insoluble CuxSe, suppressing polyselenide shuttling and improving kinetics (low polarization of ~0.1 V).
• Achieved a significantly elevated selenium redox potential (+0.5 V vs SHE) and a high discharge voltage of 3.5 V in a hybrid lithium-selenium battery.

Conclusions:

• Demonstrated the feasibility of copper-ion-mediated selenium electrochemistry in nonaqueous media.
• This approach offers a promising pathway to high-voltage, high-performance selenium-based rechargeable batteries.
• The developed system effectively addresses key limitations of conventional selenium batteries.