Functionalized Separator with Integrated Mass Transfer Selectivity and Kinetics Regulation toward Durable Zn Anodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Limited durability of zinc anodes in aqueous zinc-ion batteries (AZIBs) is primarily due to disordered ion transport and sluggish kinetics.
• Developing advanced separators is crucial for enhancing AZIB performance and stability.

Purpose of the Study:

• To develop a functional separator, bacterial cellulose functionalized with boehmite (BM/BC), to regulate ion flux and improve Zn2+ transport kinetics.
• To enhance the selectivity and suppress interfacial side reactions in AZIBs.

Main Methods:

• Fabrication of a BM/BC functional separator.
• Investigation of the separator's interaction with electrolyte species (H2O and SO42-) through coordination effects.
• Evaluation of Zn2+ desolvation, selective migration, and diffusion barriers.
• Testing of Zn||Zn symmetric batteries, Zn||MnO2 full batteries, and pouch cells.

Main Results:

• The BM/BC separator effectively anchors H2O and SO42- anions, facilitating Zn2+ desolvation and selective migration.
• Achieved an exceptional Zn2+ transference number of 0.81 and significantly suppressed interfacial side reactions.
• Demonstrated extended lifespan (>2900 h) in symmetric cells, stable cycling (>1000 cycles) in full cells, and robust performance in pouch configurations.

Conclusions:

• The BM/BC separator provides a feasible strategy for designing advanced separators for high-performance AZIBs.
• The study offers fundamental insights into regulating ion flux and mitigating interfacial degradation in zinc anodes.