Formulating Interfacial Impedances for Designing High-Energy and High-Power All-Solid-State Battery Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state batteries (ASSBs) offer enhanced safety and energy density compared to conventional lithium-ion batteries.
• However, their widespread adoption is hindered by low power performance, primarily due to high interfacial impedances within composite cathodes.

Purpose of the Study:

• To quantitatively analyze the interfacial factors limiting power performance in ASSBs.
• To elucidate the relationship between cathode active material (CAM) particle size and interfacial resistances.

Main Methods:

• Utilized impedance spectroscopy to measure interfacial impedance components: grain-boundary resistance (r_i,gb) and charge-transfer resistance (r_i/e).
• Systematically varied CAM particle size to investigate its impact on cathodic resistance.

Main Results:

• Observed an inverse relationship between CAM particle size and cathodic resistance: smaller particles led to higher resistance.
• Identified a trade-off: smaller CAM particles resulted in lower charge-transfer resistance but significantly higher grain-boundary resistance due to increased porosity.
• This phenomenon is specific to ASSBs and not observed in liquid-electrolyte batteries.

Conclusions:

• Composite cathode design significantly impacts the performance of ASSBs.
• Managing the trade-off between grain-boundary and charge-transfer resistance through strategic CAM particle engineering is crucial for achieving stable, high-power, and high-energy ASSBs.