Spatiotemporal Coordination-Engineered Core-Shell Zeolitic Imidazolate Frameworks Enable Self-Adaptive...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but suffer from polysulfide shuttle and poor cycling stability.
• Electrocatalyst design is crucial for mitigating these issues by controlling lithium polysulfide (LiPSs) interactions and conversion kinetics.

Purpose of the Study:

• To develop a novel heterogeneous electrocatalyst with a core-shell structure for enhanced Li-S battery performance.
• To elucidate the role of spatial arrangement of ionic and covalent components in LiPSs conversion and Li+ transport.

Main Methods:

• Fabrication of a core-shell zeolite imidazolate framework (ZIF) electrocatalyst incorporating ionic Zn and covalent Co.
• In situ characterization to study the dynamic reconstruction of the catalyst's spatial landscape during cycling.
• Electrochemical testing of Li-S pouch cells to evaluate cycling stability and energy density.

Main Results:

• The core-shell structure with Zn-N shell and Co-(S)-Zn-(N) core demonstrated efficient Li+ transport and bidirectional LiPSs electrocatalysis.
• The designed catalyst enabled self-adaptive reconstruction and self-tandem LiPSs conversion, leading to stable cycling for 100 cycles at 1C in an Ah-level pouch cell.
• A high energy density of 374 W h kg-1 was achieved with a low electrolyte-to-sulfur ratio.

Conclusions:

• Spatial architecture of heterogeneous electrocatalysts is critical for optimizing Li-S battery performance.
• The proposed core-shell design paradigm offers a promising strategy for developing advanced Li-S batteries with high energy density and long cycle life.