Interfacial Coordination Engineering to Boost Li-Ion Conduction in Economic Zr-Based Halide Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Halide solid electrolytes (HSEs) are crucial for all-solid-state lithium batteries (ASSLBs).
• Achieving high ionic conductivity and low cost in HSEs remains a challenge.
• Existing high-conductivity halides use expensive metals, while cost-effective Zr-based halides have low conductivity.

Purpose of the Study:

• To develop a novel composite electrolyte with enhanced ionic conductivity and cost-effectiveness.
• To investigate the interfacial coordination reaction between Zr-based oxychlorides (LZCO) and Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP).
• To evaluate the performance of the composite electrolyte in ASSLBs with high-voltage cathodes.

Main Methods:

• Synthesized a composite electrolyte (LA/LZCO) via interfacial coordination between LZCO and LATP.
• Characterized the structural changes and ionic conductivity of the composite electrolyte.
• Fabricated ASSLBs using the LA/LZCO electrolyte and NCM83125 cathodes.
• Tested the cycling stability and capacity retention of the ASSLBs at various C-rates and cut-off voltages.

Main Results:

• The LA/LZCO composite electrolyte exhibited a twofold increase in ionic conductivity compared to LZCO, reaching 2.81 mS cm^-1.
• The coordination between LATP's PO₄ ^3- groups and LZCO's Zr⁴⁺ induced amorphization and enhanced conductivity.
• ASSLBs with the composite electrolyte showed excellent cycling stability: 92.4% retention at 0.5 C and 87.5% at 2 C after 1000 cycles (4.25 V).
• High capacity retention of 85.1% after 380 cycles was achieved even at an elevated cut-off voltage of 4.5 V.

Conclusions:

• The developed LA/LZCO composite electrolyte offers a promising strategy for high-performance ASSLBs.
• The interfacial coordination approach effectively enhances ionic conductivity and electrochemical stability.
• This work contributes to the development of cost-effective, high-energy, and long-life solid-state batteries.