Integrated, Flexible Lithium Metal Battery with Improved Mechanical and Electrochemical Cycling Stability

The success of beyond lithium-ion battery (LIB) technologies, i.e., Li oxygen and Li-S cells, depends in large part on the use of metallic anode materials. Metallic lithium, however, tends to grow parasitic dendrites, which would penetrate the separator to cause safety concerns. Moreover, the dendrites are highly reactive to carbonate electrolytes and invariably render a reduced Coulombic efficiency. Here, we propose our design of a dendrite blocking layer with size-tunable Ag nanoparticles (NPs) decorated on the mesoporous SiO₂ nanospheres. The synergistic coupling of these complementary components enables the effective regulation of the lithium nucleation behavior via a protected Li-Ag alloying process. The Li plating/stripping process of a symmetric Ag NPs@SiO₂-coated Li-metal cell exhibits a reduced voltage hysteresis, facile lithium nucleation process, and enhanced Coulombic efficiencies at various current densities. When the Ag NPs@SiO₂-coated copper foil anode was integrated with lithium manganese oxide (LMO) or sulfur (S) cathodes in full-cell configurations, both the Li-LMO and the Li-S cells exhibit high energy densities with a Coulombic efficiency of -98.5% for 150 cycles. Furthermore, a flexible metallic cell model with satisfactory mechanical and electrochemical cycling stability (up to 1750 h) was established. The prototype directly integrates the modified polyethylene (PE) separator with the Ag NPs@SiO₂ dendrite blocking layer. Our approach could lead to the simultaneous realization of high energy density, mechanical flexibility, and safe operation of Li-metal-based batteries.