Polymer-Ion Interaction Prompted Quasi-Solid Electrolyte for Room-Temperature High-Performance Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Quasi-solid gel electrolytes (QSEs) offer enhanced safety for lithium-ion batteries.
• Commercialization is limited by low ionic conductivity and poor interfacial contact.
• Solvent co-intercalation in graphite anodes causes exfoliation, degrading battery performance.

Purpose of the Study:

• To develop a QSE that overcomes limitations of current lithium-ion battery electrolytes.
• To investigate the mechanism of preventing graphite exfoliation in QSEs.
• To evaluate the performance and safety of QSEs in high-energy-density batteries.

Main Methods:

• In situ polymerization of methyl methacrylate (MMA) in a 1,2-dimethoxyethane (DME)-based electrolyte to form a QSE.
• Fabrication and testing of high-loading graphite||LiNi0.8Co0.1Mn0.1O2 (NCM811) pouch cells with the developed QSE.
• Electrochemical performance evaluation, including C-rate capability, cycle life, and safety tests.
• Comparative analysis with liquid carbonate electrolyte cells and other high-energy-density battery systems.

Main Results:

• The QSE successfully prohibited graphite exfoliation due to its unique solvent-lacking solvation structure.
• Graphite||NCM811 pouch cells demonstrated superior C-rate capability at high cathode mass loading (17.5 mg cm-2), outperforming liquid electrolyte cells.
• Optimized QSEs based on carbonates showed excellent cycle life (92.4% capacity retention after 1700 cycles) and reliable safety.
• The QSE technology proved effective in high-energy-density batteries with significant volume changes.

Conclusions:

• The developed QSE effectively prevents graphite exfoliation, a critical issue in lithium-ion batteries.
• The QSE offers enhanced ionic conductivity and interfacial contact, leading to superior electrochemical performance.
• This study highlights the polymer's crucial role in QSEs, providing insights for advancing quasi-solid-state battery commercialization.