Stack Pressure Considerations for Room Temperature All-Solid-State Lithium Metal Batteries

TL;DR

This study investigates how stack pressure affects lithium metal failure in all-solid-state batteries, demonstrating that moderate pressure enables stable cycling and long-term operation at room temperature.

Contribution

It provides new insights into the role of stack pressure on lithium dendrite suppression and demonstrates reliable cycling under practical pressure conditions.

Findings

Low stack pressure of 5 MPa enables over 1000 hours of stable cycling.

Full cells can cycle over 200 times at room temperature with lithium plating.

Stack pressure significantly influences interfacial stability and failure mechanisms.

Abstract

All-solid-state batteries are expected to enable batteries with high energy density with the use of lithium metal anodes. Although solid electrolytes are believed to be mechanically strong enough to prevent lithium dendrites from propagating, various reports today still show cell failure due to lithium dendritic growth at room temperature. While cell parameters such as current density, electrolyte porosity and interfacial properties have been investigated, mechanical properties of lithium metal and the role of applied stack pressure on the shorting behavior is still poorly understood. Here, we investigated failure mechanisms of lithium metal in all-solid-state batteries as a function of stack pressure, and conducted in situ characterization of the interfacial and morphological properties of the buried lithium in solid electrolytes. We found that a low stack pressure of 5 MPa allows reliable plating and stripping in a lithium symmetric cell for more than 1000 hours, and a Li | Li6PS5Cl | LiNi0.80Co0.15Al0.05O2 full cell, plating more than 4 um of lithium per charge, is able to cycle over 200 cycles at room temperature. These results suggest the possibility of enabling the lithium metal anode in all-solid-state batteries at reasonable stack pressures.