Regulating capillary pressure to achieve ultralow areal mass loading metallic lithium anodes

Abstract

Placing metallic Li inside 3D porous scaffold is effective to improve its reversibility. However, in most cases, excessive Li jeopardizes energy density of cells, and causes deterioration of electrochemical performances, due to uncontrollable thermal infusion process. Herein, by analyzing parameters that influence capillary pressure acting on molten Li using Young-Laplace equation, a novel strategy to control Li content in 3D scaffolds by regulating pore size and surface lithiophilicity of scaffolds is proposed. Especially, choosing lightweight 3D graphene with tunable surface lithiophilicity as the scaffold can generate appropriate capillary pressure to achieve ultralow areal mass loading (1.8 mg cm−2) of Li. The as-prepared Li anode possesses comparable weight with thinnest commercial Li foil, but exhibits improved reversibility to sustain 700 h of stable stripping/plating at 3.0 mAh cm−2. Moreover, the relationship between areal Li loading and lithiophilicity of graphene scaffold is established. Thus, the areal loadings of Li can be tuned in a wide range from 1.8 mg cm−2 to over 9.0 mg cm−2, making this novel anode applicable to pair with a variety of high areal loading (∼10 mg cm−2) cathodes, including lithium iron phosphate, Li-rich layered oxide and sulfur, showing great application potentials in practical Li metal batteries.