The phantom menace of dynamic soft-shorts in solid-state battery research

Molten sodium batteries: advances in chemistries, electrolytes, and interfaces

“…The importance of Mode II has also been emphasized in electrolyte studies for solid-state batteries and its influence in molten Na batteries should be further explored (Han et al, 2019;Gorai et al, 2021;Wang et al, 2022;Shao et al, 2023). Detailed electrolyte studies utilizing unidirectional testing, conductivity vs. temperature series, and operando imaging would be beneficial to further understanding these important failure mechanisms (Fuchs et al, 2023;Counihan et al, 2024).…”

Hydride-Based Interlayer for Solid-State Anode-Free Battery

“…The entire process may be accelerated by the melting of Li dendrites, as internal short-circuiting is known for Joule heat generation. 41,43,44 When Li dendrites cannot be sustained by the mechanical deformation and infiltration of bulk Li, the cell voltage and stack pressure start to rise again in Stage IV (Figure 5 This proposed mechanism, which combines chemical reduction and electrochemical oxidation of NCA with macroscopic Li deformation, is supported by the increased full-cell resistance due to the severe chemical reactions between NCA and Li dendrites after the ninth discharge (Figure S13). As shown in Figure S14, galvanotactic electrochemical impedance spectra (GEIS) were also used to study the soft-shorting mechanism.…”

“…This type of cell failure is not exclusive to our anode-free batteries, it has been reported in solid-state Li metal batteries, ,− commonly described as “soft shorting” or “shorting” due to Li dendrite formation. Combining semiquantitative impedance analysis and computational modeling, Counihan et al provided a very detailed study on the dynamic behavior of soft-shorting in Li metal based symmetric and half cells with polymer-ceramic composite electrolyte and highlights possible mechanisms of forming, unshorting, and reshorting during soft-shorting. The detailed mechanisms of soft-shorting in an anode-free full cell with a sulfide-based solid electrolyte, to our knowledge, have not been reported.…”

“…During the early appearance of Li dendrites, their content is limited. Li dendrites chemically reduce the charged NCA, lowering the cathode potential . Once the dendrites are chemically reacted, the cathode potential increases again due to electrochemical charging (or oxidation) of NCA by the applied current, and SE also regains its function to transport lithium ions until the next dendrite-NCA contact, thereby resuming Li plating and the corresponding stack pressure increase.…”

“…However, not all the plated Li infiltrates the SE because the pressure change does not drop to 0 MPa. The entire process may be accelerated by the melting of Li dendrites, as internal short-circuiting is known for Joule heat generation. ,, …”