A Resilient Sponge-Like Separator by Confined Microfluid Phase Separation for Stabilizing Lithium-Metal Anode

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Polyolefin separators are commercially successful but struggle with electrode interface stability in lithium-metal batteries.
• Stabilizing electrode interfaces is crucial for the performance and longevity of lithium-metal batteries.

Purpose of the Study:

• To develop a resilient sponge-like separator (RSLS) to address the challenge of stabilizing electrode interfaces in lithium-metal batteries.
• To investigate the role of the separator's porous structure in regulating lithium deposition and anode stability.

Main Methods:

• Fabrication of RSLS using confined microfluidic phase separation (CMPS) of poly(vinylidene fluoride) solution.
• Coating the RSLS onto a commercial polyolefin separator.
• Characterization of the RSLS structure and its performance in lithium-metal battery cells (Li|RSLS|Cu and NCM|RSLS|Li).

Main Results:

• The CMPS process allowed control over the sponge-like porous network structure of the RSLS.
• Optimized RSLS demonstrated improved electrolyte wettability and thermal-shrinkage resistance.
• RSLS effectively regulated lithium deposition, stabilized the lithium-metal anode surface, extended cycle life, and reduced polarization voltage.
• NCM|RSLS|Li batteries showed higher discharge capacity and enhanced cycling stability, even at high rates.

Conclusions:

• The resilient sponge-like separator (RSLS) significantly enhances lithium-metal battery performance by stabilizing the anode.
• The adaptive pore network of RSLS plays a critical role in managing lithium deposition and volume changes.
• This study highlights the importance of resilient separator design for advanced battery applications.