Tuning Inactive Phases in Si-Ti-B Ternary Alloy Anodes to Achieve Stable Cycling for High-Energy-Density Lithium-Ion Batteries

Realizing fast-charging capability of silicon anode via ternary doping and structural disorder

Silicon (Si) is a potential fast-charging anode material for lithium-ion batteries (LIBs) due to its high energy density and suitable lithium insertion potential. However, the slow kinetics and significant volume changes during lithiation/delithiation hinder its practical application. High-entropy alloying of silicon enhances electronic conductivity and mitigates volume expansion, leading to improved rate performance. Nevertheless, the synergistic effects of high-entropy alloying and crystal structure on silicon-based anodes remain underexplored. Herein, a ternary doping alloy (Si-FeTiP) anode material with an amorphous structure was prepared via high-energy ball milling. The uniformly distributed microcrystalline phases of FeSi2 and TiP enhanced the electronic conductivity and structural stability of the Si anode. The local disordered structure of the amorphous silicon phase mitigates lithiation-induced stress, while the isotropic nature of the amorphous structure facilitates excellent Li+ diffusion kinetics in the Si-FeTiP composite. As a result, the Si-FeTiP anode exhibits an excellent rate capability of 658 mAh g-1 at 10 A g-1 and a capacity retention of 80.3 % after 500 cycles at 2 A g-1. This study enhances our understanding of how crystal structure influences ion transport and electrochemical performance. Furthermore, it provides valuable insights for the design of multivariate fast-charging silicon-based anode materials.

Scalable Synthesis of a Porous Micro Si/Si-Ti Alloy Anode for Lithium-Ion Battery from Recovery of Titanium-Blast Furnace Slag

The extensive utilization of Si-anode-based lithium-ion batteries faces obstacles due to their substantial volume expansion, limited intrinsic conductivity, and low initial Coulombic efficiency (ICE). In this study, we present a straightforward, cost-effective, yet scalable method for producing a porous micro Si/Si-Ti alloy anode. This method utilizes titanium-blast furnace slag (TBFS) as a raw material and combines aluminothermic reduction with acid etching. By adjusting the Al:TBFS ratio, the specific surface area of the material can be facilely tailored, ranging from 25.89 to 43.23 m2 g-1, enhancing the ICE from 78.2 to 85.5%. The incorporation of the Si-Ti alloy skeleton and porous structure contributes to the enhanced cyclic stability (capacity retention from 50.7 to 96.9%) and conductivity (Rct from 107.7 to 76.6 Ω). The Si/Si-Ti anode exhibits excellent electrochemical performance, including delivering a specific capacity of 1161 mAh g-1 at 200 mA g-1 after 200 cycles and 1112 mAh g-1 at 500 mA g-1 after 100 cycles, with an improved ICE of 81.2%. This study introduces a successful methodology for designing novel Si anodes from recycling waste materials, providing valuable insights for future advancements in this area.

Partially Carbonized Polymer Binder with Polymer Dots for Silicon Anodes in Lithium-Ion Batteries

Large-scale applications of conventional conductive binders for silicon (Si) anodes are challenging to accomplish due to their complex synthesis steps and high cost. Herein, a carbonized polymer dots-assisted polyvinyl alcohol-chitosan (PVA-CS-CPDs) binder is developed through a simple and low-cost hydrothermal method. Through rational design, the PVA-CS-CPDs binder retains rich polar groups while forming conjugated structures. The conjugated structure endows the PVA-CS-CPDs with high electronic conductivity, and the retained polar groups maintain strong binding strength. The proposed water-soluble binding system acts as both a binder and conductive additive, enabling stable cycling for high-Si-content (90 wt.%) anodes without any other conductive additives.