A Brief Overview of Silicon Nanoparticles as Anode Material: A Transition from Lithium-Ion to Sodium-Ion Batteries

The successful utilization of silicon nanoparticles (Si-NPs) to enhance the performance of Li-ion batteries (LIBs) has demonstrated their potential as high-capacity anode materials for next-generation LIBs. Additionally, the availability and relatively low cost of sodium resources have a significant influence on developing Na-ion batteries (SIBs). Despite the unique properties of Si-NPs as SIBs anode material, limited study has been conducted on their application in these batteries. However, the knowledge gained from using Si-NPs in LIBs can be applied to develop Si-based anodes in SIBs by employing similar strategies to overcome their drawbacks. In this review, a brief history of Si-NPs' usage in LIBs is provided and discuss the strategies employed to overcome the challenges, aiming to inspire and offer valuable insights to guide future research endeavors.

Homogenizing Silicon Domains in SiOx Anode during Cycling and Enhancing Battery Performance via Magnesium Doping

SiOx (x ≈ 1) is one of the most promising anode materials for application in secondary lithium-ion batteries because of its high theoretical capacity. Despite this merit, SiOx has a poor initial Coulombic efficiency, which impedes its widespread use. To overcome this limitation, in this work, we successfully demonstrate a novel synthesis of Mg-doped SiOx via a mass-producible physical vapor deposition method. The solid-state reaction between Mg and SiOx produces Si and electrochemically inert magnesium silicate, thus increasing the initial Coulombic efficiency. The Mg doping concentration determines the phase of the magnesium silicate domains, the size of the Si domains, and the heterogeneity of these two domains. Detailed electron microscopy and synchrotron-based analysis revealed that the nanoscale homogeneity of magnesium silicates driven by cycling significantly affected the lifetime. We found that 8 wt % Mg is the most optimized concentration for enhanced cyclability because MgSiO3, which is the dominant magnesium silicate composition, can be homogeneously mixed with silicon clusters, preventing their aggregation during cycling and suppressing void formation.

Metal-Organic Frameworks-Derived Mesoporous Si/SiOx @NC Nanospheres as a Long-Lifespan Anode Material for Lithium-Ion Batteries

Silicon (Si)-based anode materials with suitable engineered nanostructures generally have improved lithium storage capabilities, which provide great promise for the electrochemical performance in lithium-ion batteries (LIBs). Herein, a metal-organic framework (MOF)-derived unique core-shell Si/SiO_x @NC structure has been synthesized by a facile magnesio-thermic reduction, in which the Si and SiO_x matrix were encapsulated by nitrogen (N)-doped carbon. Importantly, the well-designed nanostructure has enough space to accommodate the volume change during the lithiation/delithiation process. The conductive porous N-doped carbon was optimized through direct carbonization and reduction of SiO₂ into Si/SiO_x simultaneously. Benefiting from the core-shell structure, the synthesized product exhibited enhanced electrochemical performance as an anode material in LIBs. Particularly, the Si/SiO_x @NC-650 anode showed the best reversible capacities up to 724 and 702 mAh g^-1 even after 100 cycles. The excellent cycling stability of Si/SiO_x @NC-650 may be attributed to the core-shell structure as well as the synergistic effect between the Si/SiO_x and MOF-derived N-doped carbon.

Self-Rearrangement of Silicon Nanoparticles Embedded in Micro-Carbon Sphere Framework for High-Energy and Long-Life Lithium-Ion Batteries

Despite its highest theoretical capacity, the practical applications of the silicon anode are still limited by severe capacity fading, which is due to pulverization of the Si particles through volume change during charge and discharge. In this study, silicon nanoparticles are embedded in micron-sized porous carbon spheres (Si-MCS) via a facile hydrothermal process in order to provide a stiff carbon framework that functions as a cage to hold the pulverized silicon pieces. The carbon framework subsequently allows these silicon pieces to rearrange themselves in restricted domains within the sphere. Unlike current carbon coating methods, the Si-MCS electrode is immune to delamination. Hence, it demonstrates unprecedented excellent cyclability (capacity retention: 93.5% after 500 cycles at 0.8 A g^-1), high rate capability (with a specific capacity of 880 mAh g^-1 at the high discharge current density of 40 A g^-1), and high volumetric capacity (814.8 mAh cm^-3) on account of increased tap density. The lithium-ion battery using the new Si-MCS anode and commercial LiNi_0.6Co_0.2Mn_0.2O₂ cathode shows a high specific energy density above 300 Wh kg^-1, which is considerably higher than that of commercial graphite anodes.

Flower-like carbon with embedded silicon nano particles as an anode material for Li-ion batteries

A novel 3-dimensional (3D) flower-like silicon/carbon composite was synthesized through spray drying method by using NaCl as the sacrificial reagent and was evaluated as an anode material for lithium ion batteries.

Polyacrylonitrile-based turbostratic graphite-like carbon wrapped silicon nanoparticles: a new-type anode material for lithium ion battery

The carbonaceous matrix formed by PAN-based turbostratic graphite-like carbon could give full play to the lithium-intercalation ability of Si nanoparticles.

Facile synthesis of N-doped carbon-coated Si/Cu alloy with enhanced cyclic performance for lithium ion batteries

Nanoparticles consisting of silicon/copper/nitrogen-doped-carbon (Si/Cu/N–C) with a Si/Cu alloy core and a N–C shell have been prepared and their cyclic life as an anode in lithium-ion batteries was significantly enhanced compared to Si/Cu alloy.

Layer-by-layer assembly modification to prepare firmly bonded Si–graphene composites for high-performance anodes

A new Si–graphene composite was fabricated by a facile LBL technique followed by thermal reduction, which exhibited excellent cycling performance and rate capability as an anode, showing a high capacity retention rate of 92.0% over 100 cycles.

Preparation and lithium storage performance of yolk–shell Si@void@C nanocomposites

This work discloses a novel synthesis method for yolk–shell Si@void@C nanocomposites as high-performance anodes in lithium ion batteries.