Volcano Plot of Transition Metal Disulfides in Aqueous Zinc Ion Storage

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Aqueous zinc-ion batteries (AZIBs) are promising for energy storage.
• Current cathode material design for AZIBs relies on interlayer spacing, which is insufficient to explain performance variations.
• Isostructural transition metal disulfides (TMDs) like VS2 and MoS2 show differing capacities despite similar spacing.

Purpose of the Study:

• To identify a new descriptor for rational design of AZIB cathode materials.
• To investigate the electronic structure's role in Zn2+ storage capacity.
• To establish a reliable screening principle for intercalation hosts.

Main Methods:

• Proposed an electronic-structure descriptor, φ (d-band center × electronegativity).
• Utilized density functional theory (DFT) calculations to correlate φ with Zn2+ adsorption energy.
• Experimentally synthesized and tested six TMDs to validate the descriptor's relationship with Zn2+ storage capacity.

Main Results:

• A strong correlation (R² = 0.94) was found between φ and Zn2+ adsorption energy via DFT.
• Experimental results revealed a volcano-type relationship between Zn2+ storage capacity and φ across six TMDs.
• No correlation was observed between Zn2+ storage capacity and interlayer spacing.

Conclusions:

• The electronic-structure descriptor φ is a superior predictor of AZIB cathode performance compared to interlayer spacing.
• This work highlights the electronic origin of host-guest interactions in multivalent ion storage.
• A new roadmap for designing efficient intercalation hosts for multivalent-ion batteries is established.