Crystal Structure of the Polymer Electrolyte Poly(ethylene oxide)3:LiCF3SO3

Area of Science:

• Materials Science
• Polymer Chemistry
• Solid-State Electrochemistry

Background:

• Ionically conducting polymers, or polymer electrolytes, are crucial for advanced energy storage and display technologies.
• Understanding the crystalline structures of polymer-salt complexes is vital for optimizing their performance.
• Poly(ethylene oxide) (PEO) based electrolytes are widely studied but their complex structures remain largely unelucidated.

Purpose of the Study:

• To determine the crystal structure of the archetypal polymer electrolyte poly(ethylene oxide)(3):LiCF(3)SO(3).
• To elucidate the coordination environment of Li(+) cations and the arrangement of polymer chains and anions.
• To provide fundamental insights into the structural basis of ion conduction in PEO-based electrolytes.

Main Methods:

• Powder X-ray diffraction (PXRD) was employed to collect diffraction data.
• Crystallographic analysis was performed to solve and refine the structure.
• Structural models were interpreted in terms of polymer chain conformation and ion coordination.

Main Results:

• The crystal structure of poly(ethylene oxide)(3):LiCF(3)SO(3) was successfully determined.
• The poly(ethylene oxide) chain adopts a helical conformation along the crystallographic b axis.
• Li(+) cations are coordinated by five oxygen atoms, interacting with both PEO ether oxygens and triflate anions.
• Triflate anions bridge two Li(+) ions, forming infinite columnar coordination complexes intertwined with PEO chains.

Conclusions:

• The determined crystal structure provides a detailed molecular-level understanding of this important polymer electrolyte.
• The columnar coordination complex structure explains the ionic conductivity pathways.
• This structural insight is fundamental for the rational design of novel polymer electrolytes for solid-state devices.