Temperature dependence of lithium anode voiding in argyrodite solid-state batteries


Schematic of the process

A team of researchers from Professor Peter Bruce's and Professor James Marrow's groups considered the void formation at the Li/ceramic electrolyte interface of an all-solid-state battery on discharge results in high local current densities, dendrites on charge, and cell failure.

In their paper, published in ACS Applied Materials Interfaces, they show that such voiding is reduced at the Li/Li6PS5Cl interface at elevated temperatures, sufficient to increase the critical current before voiding and cell failure from <0.25 mA cm-2 at 25oC to 0.25 mA cm-2 at 60oC and 0.5 mA cm-2 at 80oC under a relatively low stack pressure of 1 MPa.

Increasing the stack-pressure to 5 MPa and temperature to 80oC permits stable cycling at 2.5 mA cm-2.  It is also shown that the charge-transfer resistance at the Li/Li6PS5Cl interface depends on pressure and temperature, with relatively high pressures required to maintain low charge-transfer resistance at -20oC.  

These results are consistent with the plastic deformation of Li metal dominating the performance of the Li anode, posing challenges for the implementation of solid-state cells with Li anodes.