A cost-effective and humidity-tolerant chloride solid electrolyte for lithium batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Chloride solid electrolytes offer desirable properties for lithium-ion batteries, including high ionic conductivity, deformability, and oxidative stability.
• However, the high cost of raw materials for current state-of-the-art chloride solid electrolytes limits their large-scale applicability.
• Developing cost-effective alternatives is crucial for advancing solid-state battery technology.

Purpose of the Study:

• To report a new, cost-effective chloride solid electrolyte, lithium zirconium chloride (Li2ZrCl6), for solid-state batteries.
• To evaluate the ionic conductivity, deformability, oxidative stability, and humidity tolerance of Li2ZrCl6.
• To demonstrate the performance of Li2ZrCl6 in a functional all-solid-state battery cell.

Main Methods:

• Synthesis and characterization of Li2ZrCl6.
• Measurement of ionic conductivity at room temperature.
• Electrochemical compatibility testing with 4V-class cathodes.
• Assessment of humidity tolerance through exposure to controlled atmosphere.
• Assembly and cycling of an all-solid-state cell using Li2ZrCl6.

Main Results:

• Li2ZrCl6 exhibits a cost-effective synthesis route with raw materials orders of magnitude cheaper than existing electrolytes.
• Achieved high ionic conductivity of 0.81 mS cm-1 at room temperature, alongside good deformability and oxidative stability.
• Demonstrated excellent humidity tolerance, with no degradation in performance after exposure to 5% relative humidity.
• An all-solid-state cell with Li2ZrCl6, Li-In anode, and LiNi0.8Mn0.1Co0.1O2 cathode showed stable capacity (~150 mAh g-1) over 200 cycles.

Conclusions:

• Li2ZrCl6 presents a promising, low-cost alternative to expensive chloride solid electrolytes.
• Its combination of high ionic conductivity, mechanical flexibility, electrochemical stability, and humidity tolerance makes it suitable for practical solid-state batteries.
• The demonstrated performance in a full cell highlights its potential for next-generation energy storage devices.