Design Principles for Alloy-Anode-Based Low-Stack-Pressure Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Mechanical Engineering

Background:

• Solid-state batteries (SSBs) with lithium (Li) alloy anodes promise improved safety and energy density.
• Current SSB research often requires high stack pressures, hindering practical implementation.
• Low stack pressure operation is vital for commercial viability and user safety.

Purpose of the Study:

• To establish a general electro-chemo-mechanical framework for predicting critical stack pressure in SSBs.
• To enable rational pairing of alloy anodes and solid electrolytes for stable interfacial operation.
• To identify design principles for achieving low stack pressure operation in SSBs.

Main Methods:

• Developed a predictive framework integrating thermodynamic and mechanical factors.
• Analyzed interfacial stability under varying stack pressures and operating conditions.
• Experimentally validated the framework using LiAl alloy anodes and Li6PS5Cl solid electrolytes.

Main Results:

• Identified three key design principles for low stack pressure operation: compliant electrolytes, hard Li-rich anodes, and optimized external conditions.
• Demonstrated stable cycling and smooth interfacial morphology for LiAl/Li6PS5Cl at pressures above the critical threshold.
• Observed poor performance and rough morphology below the critical stack pressure.

Conclusions:

• The established framework provides a rational approach for selecting anode-electrolyte pairs in SSBs.
• Achieving low stack pressure is feasible through careful material selection and operational condition optimization.
• This work offers critical insights for the practical development of safe and high-energy-density solid-state batteries.