Intercalating Sn/Fe Nanoparticles in Compact Carbon Monolith for Enhanced Lithium Ion Storage

Sustaining Surface Lithiophilicity of Ultrathin Li-Alloy Coating Layers on Current Collector for Zero-Excess Li-Metal Batteries

Zero-excess Li-metal batteries (ZE-LMBs) have emerged as the ultimate battery platform, offering an exceptionally high energy density. However, the absence of Li-hosting materials results in uncontrolled dendritic Li deposition on the Cu current collector, leading to chronic loss of Li inventory and severe electrolyte decomposition, limiting its full utilization upon cycling. This study presents the application of ultrathin (≈50 nm) coatings comprising six metallic layers (Cu, Ag, Au, Pt, W, and Fe) on Cu substrates in order to provide insights into the design of Li-depositing current collectors for stable ZE-LMB operation. In contrast to non-alloy Cu, W, and Fe coatings, Ag, Au, and Pt coatings can enhance surface lithiophilicity, effectively suppressing Li dendrite growth, thereby improving Li reversibility. Considering the distinct Li-alloying behaviors, particularly solid-solution and/or intermetallic phase formation, Pt-coated Cu current collectors maintain surface lithiophilicity over repeated Li plating/stripping cycles by preserving the original coating layer, thereby attaining better cycling performance of ZE-LMBs. This highlights the importance of selecting suitable Li-alloy metals to sustain surface lithiophilicity throughout cycling to regulate dendrite-less Li plating and improve the electrochemical stability of ZE-LMBs.

Strategy for enhanced performance of silicon nanoparticle anodes for lithium-ion batteries

The modification of silicon nanoparticles for lithium-ion battery anode materials has been a hot exploration subject in light of their excellent volume buffering performance. However, huge volume expansion leads to an unstable solid electrolyte interface (SEI) layer on the surface of the silicon anode material, resulting in short cell cycle life, which is an important factor limiting the application of silicon nanoparticles. Herein, a dual protection strategy to improve the cycling stability of commercial silicon nanoparticles is demonstrated. Specifically, the Si/s-C@TiO2 composite was produced by the hydrothermal method to achieve the embedding of commercial silicon nanoparticles in spherical carbon and the coating of the amorphous TiO2 shell on the outer surface. Buffering of silicon nanoparticle volume expansion by spherical carbon and also the stabilization of the TiO2 shell with high mechanical strength on the surface constructed a stable outer surface SEI layer of the new Si/s-C@TiO2 electrode during longer cycling. In addition, the spherical carbon and lithiated TiO2 further enhanced the electronic and ionic conductivity of the composite. Electrochemical measurements showed that the Si/s-C@TiO2 composite exhibited excellent lithium storage performance (780 mA h g-1 after 100 cycles at a current density of 0.2 A g-1 with a coulombic efficiency of 99%). Our strategy offers new ideas for the production of high stability and high-performance anode materials for lithium-ion batteries.