Short Circuit of Symmetrical Li/Li Cell in Li Metal Anode Research

Abstract

Lithium is a promising anode material for next-generation highenergy-density rechargeable batteries owing to its high specific capacity, low density, and low electrochemical reduction potential. However, dendrite growth during cycling impedes its practical application and causes safety hazards. Extensive research has been conducted to obtain dendrite-free safe Li anodes with an extended cycle life by electrolyte or anode surface modification. In previous studies, the symmetrical Li/Li cell test was widely applied to evaluate the effect of various Li anode modification methods on the cycle stability and Li deposition overpotential. However, a general criterion has not yet been established to identify the short circuit in Li/Li cells. Some researchers have even made incorrect conclusions based on the Li/Li cycling data. The most common misjudgment is the ignorance of short circuit signals and mixing up of soft short circuit and normal potential decrease caused by electrode activation. In some studies, the fractal voltage signals were attributed to the unstable activation process of the symmetrical cell. Therefore, this study uses an in situ optical cell to demonstrate that a short circuit caused by the contact of dendrites from two opposite electrodes can cause a sudden drop in cell voltage to certain extent. According to the reversibility of the voltage, the short circuit induced by dendrite growth can be classified into unrecoverable hard short circuits and recoverable soft short circuits. Typical short circuit data were summarized and described to establish a rule to determine the different types of short circuits. The voltage profiles provide characteristic signals to distinguish between the soft short circuit, hard short circuit, and cell activation processes in symmetrical cells. Furthermore, this study provides a reference for identifying dendrite growth and cell short circuits, which is important for confirming the practical effect of different modification methods.

Self-Healing Solid Polymer Electrolyte with High Ion Conductivity and Super Stretchability for All-Solid Zinc-Ion Batteries

“…The overpotential of the Zn/Zn symmetrical cell decreased during the initial several cycles. Lemmon et al discussed this phenomenon in detail . There were mainly two reasons that would cause the decrease in overpotential in initial cycles.…”

Eliminating Dendrites and Side Reactions via a Multifunctional ZnSe Protective Layer toward Advanced Aqueous Zn Metal Batteries

“…This behavior clearly demonstrates an irreversible hard short‐circuit phenomenon, suggesting a complete short circuit and the failure of the battery due to the accumulation of dendrites. [ 41 ] Thus, under such severe conditions, uncontrollable Zn dendrite growth causes rapid failure of the unprotected Zn anode. Conversely, the Zn@ZnSe cell can stabilize for more than 160 h under these harsh conditions, with an average polarization voltage of only ≈50 mV.…”

Iongel Soft Solid Electrolytes Based on [DEME][TFSI] Ionic Liquid for Low Polarization Lithium‐O2 Batteries

“…Then, they suffered from a "soft" short-circuit, showed off by voltage drops caused by lithium dendrites growth. [46][47][48] Higher concentrated Iongel-32 mol % cells had lower overpotential (~0.2 V) for 14 h, and then showed a sharp polarization increase until cell death. Same test was also done on liquid equivalent cells (Figure S6b).…”

“…Iongel‐13 mol % and Iongel‐20 mol % cells behaved very similarly, with ∼0.7 V overpotentials after 27 and 18 h, respectively. Then, they suffered from a “soft” short‐circuit, showed off by voltage drops caused by lithium dendrites growth [46–48] . Higher concentrated Iongel‐32 mol % cells had lower overpotential (∼0.2 V) for 14 h, and then showed a sharp polarization increase until cell death.…”