Ion-Conductive Polyphosphasiloxane Networks: Constructing Robust Solid Electrolyte Interphase for SiO _x Anode.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Silicon (Si) anodes offer high capacity but suffer from volume expansion and poor cycling stability.
• Existing strategies for solid electrolyte interphase (SEI) modification are often ineffective for high-Si content anodes.
• Improving ionic conductivity and mitigating volume changes are critical for practical Si-based anodes.

Purpose of the Study:

• To develop a robust and ion-conductive SEI for SiO_x anodes using a novel polyphosphasiloxane (PPS) network.
• To enhance the cycling performance and stability of Si-based anodes.
• To investigate the role of electrolyte additives in SEI formation and its impact on battery performance.

Main Methods:

• Constructing a PPS network on SiO_x anodes via condensation of tetraethyl orthosilicate (TEOS) and tris(trimethylsilyl)phosphate (TMSP) electrolyte additives.
• Analyzing the PPS network's structure, ionic conductivity, and Li⁺ transport properties.
• Evaluating the electrochemical performance of modified SiO_x anodes in half-cells, focusing on cycling stability and capacity retention.

Main Results:

• The PPS network with Si-O-P bonds demonstrated low Li⁺ transport barriers and high ionic conductivity.
• The robust SEI effectively mitigated the volume changes of the SiO_x anode.
• The modified SiO_x anode achieved superior cycling performance over 700 cycles with 73.4% capacity retention at 0.4 C and a low decay rate of 0.038% per cycle.

Conclusions:

• The developed PPS network provides an effective strategy for creating stable and conductive SEI layers on Si-based anodes.
• TEOS/TMSP electrolyte additives are promising for enhancing the performance of high-Si content anodes.
• This work offers valuable insights for designing advanced electrolytes and SEI layers for next-generation batteries.