The Regulation of Lithium Plating Behavior by State of Stripping in Working Lithium Metal Anode

Abstract

The enthusiasm of reviving lithium metal anodes has motivated the battery community to pursue higher Li utilization. To this end, an exhaustively complete stripping pattern (C‐stripping) is conventionally adopted to obtain a higher apparent Coulombic efficiency (CE) in individual cycles while ignoring the effects of Li stripping state on subsequent Li plating behavior. In this contribution, a partial stripping (P‐stripping) protocol, in which a tiny amount of active Li is intentionally reserved, is validated as beneficial for an improved realistic Li reversibility. Compared to the C‐stripping protocol, the partially reserved active Li in P‐stripping mode serves critically as nucleation sites for following Li plating, which not only reduces the nucleation overpotential for flattened Li deposition morphology, but also favorably facilitates the re‐utilization of the original solid electrolyte interphase (SEI). This explains the lower growth rates of both “dead Li” and SEI‐Li+ under the P‐stripping protocol. Benefitting from the intrinsically more reversible Li cycling, the anode‐free Cu||LiNi0.5Co0.2Mn0.3O2 cells using the P‐stripping protocol acquire higher available capacities in long‐term cycles. This work uncovers the crucial significance of the former state of Li stripping on regulating the following Li plating manner and SEI re‐utilization, providing fresh design implications toward more sustainable cycling of Li anodes.

Impact of High-Nickel Cathodes and Test Conditions on the Coulombic Efficiency of Lithium Metal in Advanced Electrolytes

“…As the current density (0.5 mA cm –2 ) was kept the same in both methods, the lower CE in the cycling method could be from the complete stripping of Li on the Cu substrate in each cycle, leaving an unfavorable substrate for the following Li plating process compared to the Li metal substrate. The result agrees with a recent study that shows a partial stripping protocol is beneficial for Li plating in the following cycle as it reserves a tiny amount of active Li on the substrate . Thus, the testing method affects the CE value even in the same Cu | Li configuration, and it should be taken into consideration when comparing Li CE in different studies …”

Revealing the synergistic effect of LiF and Li3N in solid electrolyte interphases for stable lithium metal batteries using in situ electrochemical atomic force microscopy

“…Nevertheless, several challenges need to be addressed before LBMs can be put into practical applications, including the uncontrolled dendrite growth and continuous consumption of fresh Li source and electrolyte components, which are responsible for the short cycle lives and safety hazards of LMBs, respectively. 4–7 The key issue is the high reactivity of Li metal making almost all organic liquid electrolytes thermodynamically unstable, further resulting in the formation of heterogeneous electrolyte decomposition species that coat the surface of anodes, which is referred to as the solid electrolyte interphase (SEI). 8,9 An ideal SEI layer can act as a physical barrier by passivating further detrimental reactions, but in fact, uncontrolled and heterogeneous SEI growth results in irreversible electrode and electrolyte degradation reactions.…”