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

Innovative Solutions for High-Performance Silicon Anodes in Lithium-Ion Batteries: Overcoming Challenges and Real-World Applications

Silicon (Si) has emerged as a potent anode material for lithium-ion batteries (LIBs), but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation, leading to material pulverization and capacity degradation. Recent research on nanostructured Si aims to mitigate volume expansion and enhance electrochemical performance, yet still grapples with issues like pulverization, unstable solid electrolyte interface (SEI) growth, and interparticle resistance. This review delves into innovative strategies for optimizing Si anodes' electrochemical performance via structural engineering, focusing on the synthesis of Si/C composites, engineering multidimensional nanostructures, and applying non-carbonaceous coatings. Forming a stable SEI is vital to prevent electrolyte decomposition and enhance Li+ transport, thereby stabilizing the Si anode interface and boosting cycling Coulombic efficiency. We also examine groundbreaking advancements such as self-healing polymers and advanced prelithiation methods to improve initial Coulombic efficiency and combat capacity loss. Our review uniquely provides a detailed examination of these strategies in real-world applications, moving beyond theoretical discussions. It offers a critical analysis of these approaches in terms of performance enhancement, scalability, and commercial feasibility. In conclusion, this review presents a comprehensive view and a forward-looking perspective on designing robust, high-performance Si-based anodes the next generation of LIBs.

Carbon Uniformly Distributed SiOx/C Composite with Excellent Structure Stability for High Performance Lithium-Ion Batteries

Silicon oxides (SiOx, 0<x<2) has been considered as one of the most promising candidate materials for high specific energy anode materials and attracted extensive attention. However, there are still some shortcomings within SiOx that extremely limit its promotion in industry, especially the large volume expansion and poor conductivity. Reasonable design of silicon oxides (SiOx) electrode material is very important to improve its energy storage performance. Here, we fabricated a novel porous SiOx/C nanohybrids based on the facile sol-gel method followed by pyrolysis, in which carbon and SiOx not only exhibited uniform distribution at the nanoscale, the stability of SiOx/C network can also be easily adjusted via controlling the hydrolysis and condensation rate of precursors in situ. Thanks to the excellent electrical conductivity and structural stability of carbon, uniform distribution of SiOx and carbon at the nanoscale, as well as the porous structure. The SiOx/C(50) electrode, with the most appropriate carbon content, delivered a high lithium storage capacity and excellent cyclability. Specifically, a reversible capacity of 808 mA h g^-1 can be achieved at 100 mA g^-1 , retaining 666 mA h g^-1 after 100 cycles. And the reversible capacity still retained ∼550 mAh g^-1 after 1200 cycles at a current density of 0.5 A g^-1 .

Recent Applications of Molecular Structures at Silicon Anode Interfaces

Silicon (Si) is a promising anode material to realize many-fold higher anode capacity in next-generation lithium-ion batteries (LIBs). Si electrochemistry has strong dependence on the property of the Si interface, and therefore, Si surface engineering has attracted considerable research interest to address the challenges of Si electrodes such as dramatic volume changes and the high reactivity of Si surface. Molecular nanostructures, including metal–organic frameworks (MOFs), covalent–organic frameworks (COFs) and monolayers, have been employed in recent years to decorate or functionalize Si anode surfaces to improve their electrochemical performance. These materials have the advantages of facile preparation, nanoscale controllability and structural diversity, and thus could be utilized as versatile platforms for Si surface modification. This review aims to summarize the recent applications of MOFs, COFs and monolayers for Si anode development. The functionalities and common design strategies of these molecular structures are demonstrated.

PTFE/EP Reinforced MOF/SiO2 Composite as a Superior Mechanically Robust Superhydrophobic Agent towards Corrosion Protection, Self-Cleaning and Anti-Icing

Organic resin cross-linking ZIF-67/SiO₂ superhydrophobic (SHPB) multilayer coating was successfully fabricated on metal substrate. The perfluoro-octyl-triethoxy silane (POTS) modified ZIF-67 and SiO₂ coating was applied on primary coated polytetrafluoroethylene (PTFE) and epoxy resin (EP) via spray coating method. Here, we present that the robust superhydrophobicity can be realized by structuring surfaces at two different length scales, with a nanostructure design to provide water repellence and a microstructure design to provide durability. The as-fabricated multilayer coating displayed superior water-repellence (CA=167.4°), chemical robustness (pH=1-14) and mechanical durability undergoing 120th linear abrasion or 35th rotatory abrasion cycle. By applying different acidic and basic corrosive media and various weathering conditions, it can still maintain superior-hydrophobicity. To get a better insight of interaction between inhibitor molecules and metal surface, density functional theory (DFT) calculations were performed, showing lower energy gap and increased binding energy of ZPS/SiO₂ /PTFE/EP (ZPS=ZIF-67+POTS) multilayer coating compared to the ZIF-67/SiO₂ /PTFE/EP, thereby supporting the experimental findings. Additionally, such coatings may be useful for applications such as anti-corrosion, self-cleaning, and anti-icing multi-functionalities.

Green and Scalable Fabrication of Sandwich-like NG/SiOx/NG Homogenous Hybrids for Superior Lithium-Ion Batteries

SiOx is considered as a promising anode for next-generation Li-ions batteries (LIBs) due to its high theoretical capacity; however, mechanical damage originated from volumetric variation during cycles, low intrinsic conductivity, and the complicated or toxic fabrication approaches critically hampered its practical application. Herein, a green, inexpensive, and scalable strategy was employed to fabricate NG/SiOx/NG (N-doped reduced graphene oxide) homogenous hybrids via a freeze-drying combined thermal decomposition method. The stable sandwich structure provided open channels for ion diffusion and relieved the mechanical stress originated from volumetric variation. The homogenous hybrids guaranteed the uniform and agglomeration-free distribution of SiOx into conductive substrate, which efficiently improved the electric conductivity of the electrodes, favoring the fast electrochemical kinetics and further relieving the volumetric variation during lithiation/delithiation. N doping modulated the disproportionation reaction of SiOx into Si and created more defects for ion storage, resulting in a high specific capacity. Deservedly, the prepared electrode exhibited a high specific capacity of 545 mAh g-1 at 2 A g-1, a high areal capacity of 2.06 mAh cm-2 after 450 cycles at 1.5 mA cm-2 in half-cell and tolerable lithium storage performance in full-cell. The green, scalable synthesis strategy and prominent electrochemical performance made the NG/SiOx/NG electrode one of the most promising practicable anodes for LIBs.

The Latest Trends in Electric Vehicles Batteries

Global energy demand is rapidly increasing due to population and economic growth, especially in large emerging countries, which will account for 90% of energy demand growth to 2035. Electric vehicles (EVs) play a paramount role in the electrification revolution towards the reduction of the carbon footprint. Here, we review all the major trends in Li-ion batteries technologies used in EVs. We conclude that only five types of cathodes are used and that most of the EV companies use Nickel Manganese Cobalt oxide (NMC). Most of the Li-ion batteries anodes are graphite-based. Positive and negative electrodes are reviewed in detail as well as future trends such as the effort to reduce the Cobalt content. The electrolyte is a liquid/gel flammable solvent usually containing a LiFeP6 salt. The electrolyte makes the battery and battery pack unsafe, which drives the research and development to replace the flammable liquid by a solid electrolyte.

Manipulating Oxidation of Silicon with Fresh Surface Enabling Stable Battery Anode

Silicon (Si)-based material is a promising anode material for next-generation lithium-ion batteries (LIBs). Herein, we report the fabrication of a silicon oxide-carbon (SiO_x/C) nanocomposite through the reaction between silicon particles with fresh surface and H₂O in a mild hydrothermal condition, as well as conducting carbon coating synchronously. We found that controllable oxidation could be realized for Si particles to produce uniform SiO_x after the removal of the native passivation layer. The uniform oxidation and conductive coating offered the as-fabricated SiO_x/C composite good stability at both particle and electrode level over electrochemical cycling. The as-fabricated SiO_x/C composite delivered a high reversible capacity of 1133 mAh g^-1 at 0.5 A g^-1 with 89.1% capacity retention after 200 cycles. With 15 wt % SiO_x/C composite, graphite-SiO_x/C hybrid electrode displayed a high reversible specific capacity of 496 mAh g^-1 and stable electrochemical cycling with a capacity retention of 90.1% for 100 cycles.

Enhanced lithium storage performance of porous Si/C composite anodes using a recrystallized NaCl template

Silicon (Si) has recently aroused great interest as a promising anode material for lithium-ion batteries with high energy density due to its high theoretical capacity. However, the application of Si remains a great challenge owing to its extremely large volume change during cycling, thus resulting in dramatic capacity fading. Herein, a novel structure design of the porous Si/C composite with Si nanoparticles embedded in the carbon nanosheets has been successfully achieved by using a recrystallized NaCl template with appropriate particle size. The outermost sheet-like carbon coating can improve the electronic conductivity and contribute to the formation of a more stable solid-electrolyte interphase layer, while the inner void space effectively buffers the volume expansion of Si during the lithiation process. In addition, only a structure with Si particles anchored on the surface of carbon nanosheets has been obtained by using a commercial NaCl template with large particle size, confirming the effective regulation of the NaCl template in the microstructure and thus the electrochemical properties of the Si/C composites. As expected, benefiting from the combination of the outermost carbon coating and recrystallized NaCl-derived porous structure, the as-obtained Si/C composite demonstrates attractive cycling stability and rate performance as an anode material for lithium-ion batteries.

Nickel doped copper ferrite NixCu1−xFe2O4 for a high crystalline anode material for lithium ion batteries

Transition metal oxides (TMO) have great potential applications in efficient energy storage devices for their commercial possibilities in lithium-ion batteries (LIBs).

Simplified Synthesis of Biomass-Derived Si/C Composites as Stable Anode Materials for Lithium-Ion Batteries

Synthesis of silicon/carbon (Si/C) composites from biomass resources could enable the effective utilization of agricultural products in the battery industry with economical as well as environmental benefits. Herein, a simplified process was developed to synthesize Si/C from biomass, by using a low-cost agricultural byproduct "rice husk (RH)" as a model. This process includes the calcination of RH for SiO₂ /C and the reduction of SiO₂ /C by Al in molten salts at a moderate temperature. This process does not need the removal of carbon before thermal reduction of SiO₂ , which is thought to be necessary to avoid the formation of SiC at elevated temperatures. Thus, carbon derived from biomass can be directly used for Si/C composites for anode materials. The resultant Si/C shows a high reversible capacity of 1309 mAh g^-1 and long cycle life (300 cycles). This research advocates a new and simplified strategy for the synthesis of RH-based biomass-derived Si/C, which is beneficial for low-cost, environmentally friendly, and green energy storage applications.