Solvation-Heterostructure Synergy Enables Reversible Four-Electron Conversion in High-Capacity Na-Ion Electrodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conversion-type electrode materials for sodium-ion storage face challenges with slow kinetics and irreversible phase transitions.
• Electrolyte solvation chemistry's role in mediating electrode phase evolution is an underexplored area.

Purpose of the Study:

• To investigate the impact of electrolyte solvation chemistry on the phase transition dynamics of conversion-type MoSe2.
• To develop a solvation engineering strategy for improved Na-ion storage performance.

Main Methods:

• Utilized dimethoxyethane (DME)-based electrolytes for solvation engineering of MoSe2.
• Systematically analyzed Na+ solvation structures and their influence on MoSe2 phase transitions.
• Investigated the electrochemical performance of MoSe2-TiO2-MXene (MTM) anodes.

Main Results:

• Tailored Na+-2DME solvation structures eliminated desolvation barriers, enabling direct co-intercalation.
• Accelerated interfacial charge transfer and reduced electrolyte decomposition were observed.
• Solvation-induced lattice expansion alleviated mechanical strain, preserving structural integrity and ion diffusion.
• A four-electron transfer process was achieved in MTM anodes, demonstrating high reversibility.

Conclusions:

• Solvation engineering is a viable strategy to control phase transition thermodynamics and kinetics in conversion electrodes.
• This approach offers universal design principles for high-performance Na-ion storage devices.