Insulative Ion-Conducting Lithium Selenide as the Artificial Solid-Electrolyte Interface Enabling Heavy-Duty Lithium Metal Operations.

The deployment of Li metal batteries has been significantly tethered by uncontrollable lithium dendrite growth, especially in heavy-duty operations. Herein, we implement an in situ surface transformation tactic exploiting the vapor-phase solid-gas reaction to construct an artificial solid-electrolyte interphase (SEI) of Li2Se on Li metal anodes. The conformal Li2Se layer with high ionic diffusivity but poor electron conductivity effectively restrains the Li/Li+ redox conversion to the Li/Li2Se interface, and further renders a smooth and chunky Li deposition through homogenized Li+ flux and promoted redox kinetics. Consequently, the as-fabricated Li@Li2Se electrodes demonstrate superb cycling stability in symmetric cells at both high capacity and current density. The merits of inhibited dendrite growth and side reactions on the stabilized Li@Li2Se anode are further manifested in Li-O2 batteries, greatly extending the cycling stability and energy efficiency.

Redox-Driven Lithium Perfusion to Fabricate Li@Ni-Foam Composites for High Lithium-Loading 3D Anodes.

As the hostless nature of the conventional Li anodes with planar surfaces inevitably causes volume expansion and parasitic dendrite growth, it is essential to develop a composite electrode structure with improved Li plating/stripping behaviors to mitigate such issues. Herein, a composite Li@NF anode was successfully fabricated through lithium perfusion into the commercial nickel foam (NF) decorated with lithiophilic NiO nanosheets, demonstrating an exceptionally high areal Li loading of 53.2 mg cm-2 with suppressed Li dendrite formation and volume expansion, improved Coulombic efficiency, as well as extended cycling stability in all half, symmetric, and full cell tests. More importantly, density functional theory calculations and control studies with Fe2O3@NF, pristine NF, and Cu2O@CF reveal a linear correlation between the thermodynamics of the surface reactions and the lithiophilicity of the reaction products, attesting to a redox-driven Li perfusion process. Further, through ex situ scanning electron and in situ optical microscopy, the enhanced performance of Li@NF is mainly attributed to the mediation of Li plating/stripping through homogenizing the Li+ flux, decentralizing local charge density, and accommodating multidirectional Li deposition by the conductive 3D scaffolds. Consequently, this study offers important insights into the driving of thermal Li perfusion through appropriate material and surface design for achieving safe and stable lithium metal anodes.