Electron-conductive binder for silicon negative electrode enabling low-pressure all-solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon electrodes are promising for high-energy all-solid-state batteries (ASSBs) but suffer from poor performance under low operating pressures.
• Existing binders often lead to side reactions or insufficient conductivity, limiting the practical application of Si electrodes in ASSBs.

Purpose of the Study:

• To develop a novel, scalable, fluorine-free, and water-processable conductive binder for Si electrodes in ASSBs.
• To address the challenge of poor electrochemical performance of Si electrodes at low operating pressures.

Main Methods:

• Synthesized and characterized poly(3,4-ethylenedioxythiophene):poly((styrene sulfonic acid)-co-(maleic acid)) (PEDOT:P(SS-co-MA)) as a binder.
• Fabricated Si electrodes using PEDOT:P(SS-co-MA) and evaluated their electrochemical performance in half and full ASSB cells.
• Conducted ex situ measurements to analyze electrode integrity and conductivity changes during cycling.

Main Results:

• PEDOT:P(SS-co-MA) demonstrated excellent e-conductivity, eliminating the need for carbon additives and ensuring strong adhesion.
• The binder effectively resolved issues of disrupted e-connectivity during delithiation at 5 MPa, improving electrode stability.
• ASSBs utilizing PEDOT:P(SS-co-MA) exhibited enhanced electrochemical performance, achieving 134 mAh g⁻¹ at 0.5 C with 86% capacity retention over 100 cycles in half cells and demonstrating high energy density in full cells.

Conclusions:

• PEDOT:P(SS-co-MA) is a highly effective binder for Si electrodes in ASSBs, overcoming limitations of previous materials.
• The binder's properties enable robust performance even under low-pressure conditions, crucial for practical ASSB applications.
• This work highlights PEDOT:P(SS-co-MA) as a promising platform for developing next-generation high-energy ASSBs.