Self-Assembled Lithiophilic Interface with Abundant Nickel-Bis(Dithiolene) Sites Enabling Highly Durable and Dendrite-Free Lithium Metal Batteries

Despite its ultrahigh theoretical capacity and ultralow redox electrochemical potential, the practical application of lithium metal anodes is still hampered by severe dendrite growth and unstable solid electrolyte interphase (SEI). Herein, a self-assembled lithiophilic interface (SALI) for regulating Li electroplating behavior is constructed by introducing a meticulously synthesized Ni-bis(dithiolene)-based molecule (NiS4-COOH) into a hybrid fluorinated ester-ether electrolyte. The NiS4-COOH molecules with carboxyl functional groups can spontaneously anchor on the Li metal surface to form a SALI, whose abundant Ni-bis(dithiolene) sites can effectively reduce the initial Li deposition overpotential and guide the subsequent uniform Li electrodeposition. Moreover, due to the interaction between the coordination unsaturated Ni atom and the negatively charged PF6-, the NiS4-COOH additive can significantly change the ionic coordination environment in the electrolyte, which is greatly conducive to suppressing PF6- decomposition, optimizing SEI composition and accelerating Li-ion transfer. Consequently, the NiS4-COOH-modified electrolyte leads to impressive electrochemical performance of Li||LiFePO4 and Li||LiNi0.8Co0.1Mn0.1O2 batteries, delivering ultrahigh Coulombic efficiencies, considerable capacity retention, and good rate performance even at high areal active material loadings. This study presents the great potential of SALIs derived from multifunctional metal-organic hybrid electrolyte additives toward high-specific-energy Li metal batteries. A self-assembled lithiophilic interface (SALI) for regulating Li electroplating behavior is constructed by introducing a meticulously synthesized Ni-bis(dithiolene)-based molecule (NiS4-COOH) into a hybrid fluorinated ester-ether electrolyte. The NiS4-COOH molecules can spontaneously anchor on the Li metal surface to form the SALI, whose abundant Ni-bis(dithiolene) sites can effectively reduce the initial Li deposition overpotential and guide subsequent uniform Li electrodeposition.image

Automated summary

A self-assembled lithiophilic interface (SALI) is constructed by introducing a meticulously synthesized Ni-bis(dithiolene)-based molecule (NiS4-COOH) into a hybrid fluorinated ester-ether electrolyte to regulate Li electroplating behavior. The SALI formed by NiS4-COOH molecules on the Li metal surface reduces the initial Li deposition overpotential and guides uniform Li electrodeposition. Additionally, the NiS4-COOH additive changes the ionic coordination environment in the electrolyte, suppressing PF6- decomposition and optimizing SEI composition, leading to impressive electrochemical performance in Li-ion batteries.