Redefining Separator Design and Water Activity for High-Energy Zinc Batteries Using Covalent Organic Framework

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Zinc metal batteries offer sustainable and safe energy storage but suffer from low device-level energy density.
• Existing research focuses on anode stability, neglecting inactive components like separators and electrolytes that limit practical energy metrics.
• Lean electrolyte operation, crucial for high energy density, presents challenges in water management and ion transport.

Purpose of the Study:

• To address the low energy density limitation in zinc metal batteries.
• To investigate failure mechanisms under lean electrolyte conditions.
• To develop a functional separator for improved water management and ion transport.

Main Methods:

• Systematic unraveling of failure mechanisms in lean electrolyte zinc metal batteries.
• Development of a novel COF@PAN separator with engineered hydrogen-bonding networks.
• Testing of the COF@PAN separator in practical pouch cells under lean electrolyte conditions.

Main Results:

• The COF@PAN separator effectively manages interfacial water and optimizes ion transport.
• Achieved unprecedented energy densities of 54.0 Wh kg⁻¹ and 185.3 Wh L⁻¹ in practical pouch cells.
• Demonstrated excellent cycle stability exceeding 800 cycles.

Conclusions:

• The developed COF@PAN separator overcomes critical limitations in lean electrolyte zinc metal batteries.
• This innovation significantly enhances energy density and cycle stability, positioning zinc metal batteries for real-world applications.
• The study provides a holistic design strategy for advancing high-energy-density metal batteries.