Stack Pressure Dependence of Li Stripping/Plating Performance in All-Solid-State Li Metal Cells Containing Sulfide Glass Electrolytes

Abstract

Sulfide-based all-solid-state Li/S batteries have attracted considerable attention as next-generation batteries with high energy density. However, their practical applications are limited by short-circuiting due to Li dendrite growth. One of the possible reasons for this phenomenon is the contact failure caused by void formation at the Li/solid electrolyte interface during Li stripping. Herein, we studied the operating conditions, such as stack pressure, operating temperature, and electrode composition, that could potentially suppress the formation of voids. Furthermore, we investigated the effects of these operating conditions on the Li stripping/plating performance of all-solid-state Li symmetric cells containing glass sulfide electrolytes with a reduction tolerance. As a result, symmetric cells with Li–Mg alloy electrodes instead of Li metal electrodes exhibited high cycling stability at current densities above 2.0 mA cm–2, a temperature of 60 °C, and stack pressures of 3–10 MPa. In addition, an all-solid-state Li/S cell with a Li–Mg alloy negative electrode operated stably for 50 cycles at a current density of 2.0 mA cm–2, stack pressure of 5 MPa, and temperature of 60 °C, while its measured capacity was close to a theoretical value. The obtained results provide guidelines for the construction of all-solid-state Li/S batteries that can reversibly operate at high current densities.

Dynamic Volume Change of Li2S-Based Active Material and the Influence of Stacking Pressure on Capacity in All-Solid-State Batteries

“…The reason for this requires further detailed investigation, but at least Li cannot be extracted from the positive electrode, which is an additional challenge for operating the cells under a low stack pressure. In previous work, the capacity of a Li–Mg/sulfur-based composite positive electrode cell was retained over more than 50 cycles at only 5 MPa . Therefore, a mechanically balanced electrode combination is expected to improve the performance of the Li 2 S-based cells.…”

“…Stainless steel or Cu foil was used as the current collector. During the electrochemical measurements, defined uniaxial stack pressures were applied and monitored in the setups as described previously. ,,, All the procedures were conducted in a dry Ar atmosphere.…”