Transport Properties and Local Ions Dynamics in LATP-Based Hybrid Solid Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Hybrid solid electrolytes (HSEs) combine polymer and inorganic components, aiming for superior properties.
• However, high interfacial resistance often hinders charge transport in HSEs, limiting their practical application.
• Lithium aluminum titanium phosphate (LATP) is a promising Li⁺-conducting ceramic filler for HSEs.

Purpose of the Study:

• To investigate the transport properties of hybrid solid electrolytes composed of polymer and Li⁺-conducting Li_(1+x)Al_xTi_(2-x)(PO₄)₃ (LATP) filler.
• To elucidate the influence of LATP concentration and temperature on ionic conductivity and Li⁺ transport mechanisms.
• To evaluate the impact of LATP addition on the mechanical properties and processability of polymer electrolytes.

Main Methods:

• Isotope exchange experiments using ⁶Li/⁷Li nuclear magnetic resonance (NMR) to confirm Li⁺ exchange.
• 2D ⁶Li exchange spectroscopy (EXSY) to determine Li⁺ exchange time constants.
• Electrochemical impedance spectroscopy (EIS) and pulsed field gradient NMR (PFG-NMR) to analyze conductivity and ion diffusion.

Main Results:

• Li⁺ exchange between polymer and LATP phases occurs with a time constant of ~50 ms at 60 °C.
• Long-range ionic conductivity decreases with increasing LATP concentration, with LATP contributing significantly only at high temperatures and concentrations.
• Addition of LATP enhances mechanical properties and processability of polymer electrolytes, improving plating/stripping performance.

Conclusions:

• The interfacial resistance in LATP/polymer hybrid solid electrolytes significantly impacts overall ionic conductivity.
• While LATP addition offers marginal improvements in Li⁺ transference number, it substantially enhances mechanical stability and processability.
• These findings suggest potential for LATP-modified polymer electrolytes in applications requiring robust mechanical performance, such as lithium-ion batteries.