Composition regulation of polyacrylonitrile-based polymer electrolytes enabling dual-interfacially stable solid-state...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Polyacrylonitrile (PAN) is a promising polymer electrolyte matrix due to its electrochemical stability and lithium salt coordination.
• PAN-based electrolytes face challenges like poor ionic conductivity and interfacial instability with lithium metal anodes.
• These issues hinder the development of high-performance solid-state lithium batteries.

Purpose of the Study:

• To address interfacial problems in PAN-based electrolytes for solid-state lithium batteries.
• To enhance ionic conductivity and electrochemical stability through composition regulation.
• To develop a stable solid-state lithium battery with improved cycling performance.

Main Methods:

• Introducing succinonitrile (SN) plastic crystal and LiNO3 salt into the PAN matrix.
• Investigating the effect of SN on ionic transfer and interfacial contact formation.
• Analyzing the in-situ formation of a stable solid-electrolyte-interface (SEI) layer.
• Evaluating the performance of Li symmetric cells and LiNi0.6Co0.2Mn0.2O2/Li full cells.

Main Results:

• The addition of SN plastic crystal and LiNO3 facilitated rapid ionic transfer and conformal interfacial contacts.
• A stable SEI layer, composed of Li3N and LiNO2, was formed at the Li/electrolyte interface, preventing unwanted reactions.
• Li symmetric cells exhibited a critical current density of 1.7 mA cm-2 and cycled for 700 hours at 0.1 mA cm-2.
• The solid-state full cell achieved an initial discharge capacity of 161 mAh/g with 88.7% capacity retention after 100 cycles at 0.1C.

Conclusions:

• Composition regulation of PAN-based electrolytes by incorporating SN and LiNO3 effectively resolves interfacial instability issues.
• The developed electrolyte enables rapid ion transport and forms a protective SEI layer, crucial for Li-metal anodes.
• This approach significantly enhances the performance and cycling stability of solid-state lithium batteries.
• The findings provide a facile strategy for advancing PAN-based electrolytes in solid-state battery applications.