Enabling fast-charging selenium-based aqueous batteries via conversion reaction with copper ions

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Selenium (Se) is a high-capacity cathode material for batteries.
• Se-based cathodes suffer from poor rate capability.
• Composite materials are needed to improve Se performance.

Purpose of the Study:

• To develop selenium@carbon (Se@C) composite cathode materials.
• To enhance the rate capability of Se-based cathodes.
• To investigate Se@C performance in aqueous copper-ion battery systems.

Main Methods:

• Fabrication of Se@C composite materials.
• Electrochemical testing of Zn||Se@C cells in 0.5 M CuSO4 electrolyte.
• Physicochemical characterizations and first-principle calculations.

Main Results:

• Lab-scale Zn||Se@C cells achieved a discharge voltage of ~1.2 V at 0.5 A g−1.
• Initial discharge capacity reached 1263 mAh gSe−1.
• Stable capacity of ~900 mAh gSe−1 was maintained at 6 A g−1 charging current, independent of discharge rate.

Conclusions:

• Se@C composites demonstrate excellent rate capability and stable cycling performance.
• Reversible structural changes in the Se-based cathode are key to battery performance.
• Aqueous copper-ion batteries utilizing Se@C cathodes are a viable energy storage option.