Double-Layer Solid Composite Electrolytes Enabling Improved Room-Temperature Cycling Performance for High-Voltage...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Developing solid-state electrolytes (SSEs) for high energy density lithium metal batteries (LMBs) requires addressing interfacial compatibility with lithium metal and stability with high-potential cathodes.
• Current SSEs often face challenges in balancing mechanical properties, ionic conductivity, and electrochemical stability.

Purpose of the Study:

• To design and fabricate novel double-layer solid composite electrolytes (SCEs) with Janus characteristics for high-voltage LMBs.
• To enhance room-temperature cycling performance by optimizing interfacial properties and ionic conductivity.

Main Methods:

• A facile two-step coating process was employed to create the double-layer SCEs.
• The electrolyte featured a high-voltage resistant poly(vinylidene fluoride) (PVDF) layer facing the cathode and a poly(ethylene oxide) (PEO) blended with PVDF layer for the lithium anode interface.
• Laponite clay was incorporated to improve mechanical properties and ionic conductivity.

Main Results:

• The synthesized PVDF/(PEO+PVDF)-L SCEs exhibited improved mechanical properties.
• Achieved high ionic conductivity of 5.2 × 10^-4 S cm^-1 and a lithium ion migration number of 0.471 at room temperature.
• Assembled NCM523|PVDF/(PEO+PVDF)-LSCEs|Li cells delivered an initial discharge capacity of 153.9 mAh g^-1 with 80.8% retention after 200 cycles at 0.3 C.

Conclusions:

• The easily manufactured double-layer SCEs demonstrate stable room-temperature operation.
• These SCEs present a promising electrolyte solution for high-voltage solid-state lithium metal batteries.
• The Janus characteristics effectively address interfacial challenges in LMBs.