Incorporating Binary Metal Oxides in Poly(ethylene oxide)-Based Solid Electrolytes by Vapor Phase Infiltration

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Vapor phase infiltration (VPI) using atomic layer deposition (ALD) allows inorganic material growth within polymers, showing promise for composite solid polymer electrolytes (CSPEs).
• Limited knowledge of VPI processes restricts the types of metal oxides, especially binary metal oxides, that can be incorporated into polymer matrices.
• Combining different metal oxides in CSPEs can leverage synergistic benefits for enhanced properties.

Purpose of the Study:

• To investigate the influence of precursor introduction order on the VPI synthesis of ZnO-Al2O3 composites within poly(ethylene oxide) (PEO).
• To understand how different incorporation sequences affect the morphology, distribution, and performance of the resulting composite solid polymer electrolytes.

Main Methods:

• Utilized vapor phase infiltration (VPI) derived from atomic layer deposition (ALD) to synthesize ZnO-Al2O3 composites within a poly(ethylene oxide) (PEO) matrix.
• Investigated two distinct precursor introduction orders: Al2O3/ZnO (AZO) and ZnO/Al2O3 (ZAO).
• Analyzed the resulting material morphology, polymer-filler interactions, and lithium-ion conduction properties.

Main Results:

• The AZO sequence (Al2O3/ZnO) resulted in surface accumulation of Al2O3 due to high trimethyl aluminum (TMA) reactivity, hindering diethyl zinc (DEZ) diffusion and limiting Li+ conduction.
• The ZAO sequence (ZnO/Al2O3) led to uniform VPI-ZnO distribution within PEO, with subsequent TMA reacting effectively, preserving polymer-filler interactions and improving lithium dendrite inhibition.
• Demonstrated that the incorporation order critically dictates the morphology and composition of VPI-synthesized binary metal oxides in PEO.

Conclusions:

• The order of precursor delivery in VPI is a crucial parameter for controlling the structure and properties of binary metal oxide-polymer composites.
• The ZnO/Al2O3 (ZAO) sequence is superior for preparing CSPEs with enhanced Li+ conduction and dendrite suppression compared to the Al2O3/ZnO (AZO) sequence.
• This study provides valuable insights into optimizing VPI synthesis for advanced composite solid polymer electrolytes.