Covalently Interlocked Electrode-Electrolyte Interface for High-Energy-Density Quasi-Solid-State Lithium-Ion...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Quasi-solid-state batteries (QSSBs) offer improved safety and performance over conventional batteries.
• High-capacity materials like silicon microparticles (SiMP) and Ni-rich cathodes (NCM811) face interfacial instability and contact loss in QSSBs due to volume fluctuations during cycling.
• Existing QSSB configurations struggle to maintain stable electrode-electrolyte contact, limiting their practical application.

Purpose of the Study:

• To develop an in situ interlocking electrode-electrolyte (IEE) system for QSSBs.
• To address the interfacial instability and contact loss issues in QSSBs utilizing high-volume-fluctuation active materials.
• To enhance the electrochemical performance, safety, and energy density of QSSBs.

Main Methods:

• An in situ interlocking electrode-electrolyte (IEE) system was designed using covalent crosslinking between acrylate-functionalized binders on active materials and crosslinkers in the quasi-solid-state electrolyte (QSSE).
• The IEE system's stability was evaluated through electrochemical cycling of SiMP||NCM811 full cells, monitoring voltage hysteresis, interfacial resistance, and void formation.
• A pressure-detecting cell kit was employed to assess pressure changes and voltage stability during cycling, and mechanical abuse tests (folding, cutting) were performed on a bi-layer pouch cell.

Main Results:

• The IEE system successfully established a robust, interconnected network, maintaining stable electrode-electrolyte contact and preventing void formation over 200 cycles.
• Low voltage hysteresis and stable interfacial resistance were observed, indicating superior electrochemical stability compared to conventional QSSB configurations.
• The SiMP||NCM811 full cell with the IEE system achieved a high energy density of 403.7 Wh kg^-1/1300 Wh L^-1 and demonstrated resilience during mechanical abuse tests.

Conclusions:

• The in situ interlocking electrode-electrolyte system effectively overcomes interfacial challenges in high-energy-density QSSBs with volume-fluctuating materials.
• This approach significantly enhances battery safety, cycle life, and energy density, paving the way for advanced QSSB technologies.
• The developed IEE system offers a promising strategy for realizing practical, high-performance quasi-solid-state batteries.