Spatially Confined Engineering Toward Deep Eutectic Electrolyte in Metal-Organic Framework Enabling Solid-State...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous electrolytes in zinc-ion batteries (ZIBs) suffer from side reactions like hydrogen evolution and dendrite growth, hindering practical application.
• Solid-state electrolytes (SSEs) offer a promising strategy to overcome these limitations in ZIBs.

Purpose of the Study:

• To design and synthesize a novel solid-state electrolyte (SSE) for high-performance and safe ZIBs.
• To investigate the ion transport properties and electrochemical stability of the new SSE.

Main Methods:

• Confining a deep eutectic electrolyte (DEE) within the nanochannels of a metal-organic framework (MOF), specifically PCN-222, to create a DEE@PCN-222 SSE.
• Characterizing the ionic conductivity, activation energy, and zinc ion transference number of the DEE@PCN-222 SSE.
• Evaluating the zinc plating/stripping behavior and the performance of solid-state ZIBs using the developed SSE through experimental and theoretical investigations.

Main Results:

• The DEE@PCN-222 SSE exhibited high ionic conductivity (3.13×10⁻⁴ S cm⁻¹), low activation energy (0.12 eV), and a high Zn²⁺ transference number (0.74).
• The unique structure of DEE@PCN-222 effectively regulated Zn²⁺ distribution and suppressed interfacial side reactions.
• The SSE enabled highly reversible Zn plating/stripping for 2476 hours and facilitated solid-state ZIBs with a specific capacity of 306 mAh g⁻¹ and 517 cycles.

Conclusions:

• The DEE@PCN-222 SSE demonstrates excellent ion transport properties and electrochemical stability, addressing key challenges in ZIBs.
• This novel SSE design offers a new pathway for developing high-safety and high-performance zinc-ion batteries.