Near-Saturated Coordinated Cations in Oxyhalide Superionic Conductors Boost High-Rate All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Amorphous oxyhalide solid electrolytes (SEs) offer excellent cathodic stability and mechanical properties for energy storage.
• Understanding the structure-property relationship in amorphous SEs is crucial for enhancing lithium-ion (Li+) transport.
• Current research lacks detailed exploration of correlations between amorphous structural characteristics and Li+ conductivity.

Purpose of the Study:

• To establish a correlation between cationic coordination saturation in amorphous oxyhalide SEs and Li+ transport behavior.
• To design and synthesize novel amorphous SEs with enhanced ionic conductivity by modulating the cationic coordination environment.
• To evaluate the performance of these novel SEs in all-solid-state lithium batteries.

Main Methods:

• Developed near-saturated coordinated cation (NSCC)-incorporated Li1.5Zr0.5M0.5Cl5.0O0.5 SEs (M = Nb or Ta).
• Investigated the impact of NSCC incorporation on vacancy concentration and Li-Cl interaction.
• Fabricated and tested all-solid-state lithium batteries using the developed SEs and a LiNi0.8Mn0.1Co0.1O2 cathode.

Main Results:

• Achieved high ionic conductivities: 2.33 mS cm-1 for Nb-LZCO and 3.88 mS cm-1 for Ta-LZCO at 25 °C.
• Demonstrated superior rate performance and cycling stability in all-solid-state lithium batteries.
• Delivered a specific capacity of 120.0 mAh g-1 at 10.0 C and 84.85% capacity retention after 2000 cycles.

Conclusions:

• Established a generalizable strategy for designing high-performance amorphous SEs by controlling the cationic coordination environment.
• The developed NSCC-incorporated SEs show significant potential for advanced solid-state lithium battery applications.
• Modulating cationic coordination saturation is key to unlocking enhanced Li+ transport in amorphous electrolytes.