Stabilizing the SiO Anode by a Highly Elastic Quasi-Solid Polyether-Based Electrolyte via an In Situ Fabrication

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Silicon monoxide (SiO) is a promising anode material for next-generation lithium-ion batteries due to its high specific capacity.
• Significant challenges for SiO anodes include substantial volume expansion during cycling and subsequent solid electrolyte interphase (SEI) destruction.
• Developing stable anode materials and electrolytes is crucial for advancing battery technology.

Purpose of the Study:

• To develop a highly elastic quasi-solid polymer electrolyte (QSPE) for silicon monoxide (SiO) anodes.
• To investigate the effectiveness of the QSPE in mitigating SiO anode volume expansion and SEI instability.
• To enhance the cyclic stability and performance of lithium-ion batteries utilizing SiO anodes.

Main Methods:

• In situ cationic ring-opening polymerization of 1,3,5-trioxane (TXE) to create the QSPE.
• Incorporation of 1,3,2-dioxathiolane 2,2-dioxide (DTD) as initiator and film-forming additive.
• Utilizing fluoroethylene carbonate as a plasticizer in the QSPE formulation.

Main Results:

• The TXE-based QSPE exhibited excellent ionic conductivity (1.36 mS cm⁻¹ at 25 °C) and a low glass-transition temperature (-94.3 °C).
• The QSPE demonstrated a high elastic modulus (42 MPa), effectively suppressing SiO anode volume expansion.
• The DTD additive facilitated the formation of a robust SEI layer with Li₂SO₃ species, improving SiO particle stability.

Conclusions:

• The developed TXE-based QSPE significantly enhances the cyclic stability of SiO anodes in lithium-ion batteries.
• The QSPE offers a promising solution for overcoming the limitations of SiO anodes, improving their practical applicability.
• The Li||SiO half-battery with the in situ QSPE achieved 81.9% capacity retention after 200 cycles, outperforming liquid electrolytes.