Unraveling the Rate‐Dependent Stability of Metal Anodes and Its Implication in Designing Cycling Protocol

Abstract

It is widely recognized that a high current rate (J) speeds up dendrite formation and thus shortens the cycle life of metal anodes. Here, an anomalous correlation is reported between elevated J and deposition/ stripping stability (decrease-increase-decrease), leading to the relative maximum stability at a moderate J. Complementary theoretical and experimental analyses suggest that such a complex relationship lies in high J's dual and contradictory roles in kinetics and thermodynamics. The wellknown former renders decreased Sand's time (τ) and deteriorative cyclic stability, while the commonly overlooked latter provides larger extra energy that accelerates nucleation rate (ν n ). Using Zn metal anode as a model system, the ν n and τ controlled nucleation-growth process is unambiguously revealed, both of which are closely related to J. Based on these findings, an initial high J discharge strategy is developed to produce abundant nuclei for uniform metal growth at standard J in the subsequent process. The protocol increases the Zn deposition/stripping lifetime from 303 to 2500 h under a cycling capacity of 1 mAh cm −2 without resorting to electrode/electrolyte modification. Furthermore, such a concept can be readily extended to Li/K metal anodes with significantly enhanced cycle life, demonstrating its universality for developing high-performance metal batteries.

Diminishing Interfacial Turbulence by Colloid‐Polymer Electrolyte to Stabilize Zinc Ion Flux for Deep‐Cycling Zn Metal Batteries

“…However, it is still far from fully solving the issues of Zn electrodes and achieving good cyclability, let alone highly stable CEs in deeply rechargeable ZMBs cycled with high capacity and current density. [7,16] Therefore, there is widespread interest in exploring compatible electrolytes to diminish interfacial turbulence and realize deeply rechargeable aqueous ZMBs.…”

Boosting Zn metal anode stability: from fundamental science to design principles

“…The perspective and research directions for future studies are proposed as follows. Establishing standardized testing conditions. Apart from current density and cycling capacity that can highly affect the stability of Zn metal anode, 88 other factors, for example, depth of discharge (DOD), electrolyte amount, and thickness of Zn metal, also have a substantial impact on Zn deposition/stripping process. These parameters greatly determine the energy density of Zn metal anodes.…”

“…Thus, higher current density ( J ) is commonly considered to promote dendrite growth and lead to a shorter lifetime. However, such a relation is not always true, as evidenced by our recent study where the relative maximum stability is observed at a moderate current density due to its double‐edged effects on the cyclic stability 88 . As shown in Figure 5C, besides the detrimental impact due to the reduced τ ( τ ∝ 1/ J 2 ), high J implies a fast nucleation rate ( ν n , ν n ∝exp(‑(1/log 2 J ))), which increases nucleation sites and contributes to enhanced stability.…”

Artificial Interphase Layer for Stabilized Zn Anodes: Progress and Prospects

“…Electroplating of metal is a centuries-old topic, which was first studied in the 1800s. [40] Numerous complexities including electrolyte bath, [41] current density, [42] applied voltage, [43] and surficial status exert influences upon the electroplated morphologies. Depositing morphologies of Zn greatly differ from case to case, including in-parallel plates, vertical hexagons, mossy structures, pits, rocky debris, and even dendrites.…”