Facile Synthesis of Si@SiC Composite as an Anode Material for Lithium-Ion Batteries

Bio-Inspired Electrodes with Rational Spatiotemporal Management for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are currently the predominant energy storage power source. However, the urgent issues of enhancing electrochemical performance, prolonging lifetime, preventing thermal runaway-caused fires, and intelligent application are obstacles to their applications. Herein, bio-inspired electrodes owning spatiotemporal management of self-healing, fast ion transport, fire-extinguishing, thermoresponsive switching, recycling, and flexibility are overviewed comprehensively, showing great promising potentials in practical application due to the significantly enhanced durability and thermal safety of LIBs. Taking advantage of the self-healing core-shell structures, binders, capsules, or liquid metal alloys, these electrodes can maintain the mechanical integrity during the lithiation-delithiation cycling. After the incorporation of fire-extinguishing binders, current collectors, or capsules, flame retardants can be released spatiotemporally during thermal runaway to ensure safety. Thermoresponsive switching electrodes are also constructed though adding thermally responsive components, which can rapidly switch LIB off under abnormal conditions and resume their functions quickly when normal operating conditions return. Finally, the challenges of bio-inspired electrode designs are presented to optimize the spatiotemporal management of LIBs. It is anticipated that the proposed electrodes with spatiotemporal management will not only promote industrial application, but also strengthen the fundamental research of bionics in energy storage.

Advances in physical vapor deposited silicon/carbon based anode materials for Li-ion batteries

This paper explores the latest developments in physical vapor deposition (PVD) techniques for fabricating silicon-carbon (Si/C) based thin films as anodes of Lithium-Ion batteries (LiBs). Properties of Si/C based materials, such as high thermal stability, electrical conductivity and mechanical strength, have addressed the critical challenges associated with the use silicon as anode material for LiBs, including as volume expansion during lithiation, structural stability and electrode degradation. The review article aims to provide recent advances in the use of Si/C-based thin film materials deposited via PVD processes as anodes for LiBs. PVD deposition processes provide numerous benefits including the precise control over the structure, thickness, morphology, as well as the design of deposited thin-film materials, and this article provides an in-depth analysis on the design and synthesis of Si/C thin films, as well as its electrochemical performance and stability when used as anode for LiBs. The primary aim of this paper is to underscore the advantages provided by PVD processes in overcoming challenges associated with using pure silicon as anode material for LiBs, or in improving the electrochemical performance of Si/C-based anode materials through the design of several Si/C films, covering both multilayer and nanocomposite Si/C film configurations outlined in sections 2 and 3, respectively. Insights into the mechanisms governing lithium-ion insertion/extraction processes within the Si/C matrix are provided, offering an understanding of the material's behavior during battery cycling.

Near zero-strain silicon oxycarbide interphases for stable Li-ion batteries

We investigate silicon oxycarbide nanotubes that incorporate Si, SiC, and silicon oxycarbide phases, which exhibit near zero-strain volume expansion, leading to reduced electrolyte decomposition. The composite effectively accommodates the formation of c-Li15Si4, as validated by in situ TEM analyses and electrochemical tests, thereby proposing a promising solution for Li-ion battery anodes.

High-Quality Epitaxial N Doped Graphene on SiC with Tunable Interfacial Interactions via Electron/Ion Bridges for Stable Lithium-Ion Storage

Tailoring the interfacial interaction in SiC-based anode materials is crucial to the accomplishment of higher energy capacities and longer cycle lives for lithium-ion storage. In this paper, atomic-scale tunable interfacial interaction is achieved by epitaxial growth of high-quality N doped graphene (NG) on SiC (NG@SiC). This well-designed NG@SiC heterojunction demonstrates an intrinsic electric field with intensive interfacial interaction, making it an ideal prototype to thoroughly understand the configurations of electron/ion bridges and the mechanisms of interatomic electron migration. Both density functional theory (DFT) analysis and electrochemical kinetic analysis reveal that these intriguing electron/ion bridges can control and tailor the interfacial interaction via the interfacial coupled chemical bonds, enhancing the interfacial charge transfer kinetics and preventing pulverization/aggregation. As a proof-of-concept study, this well-designed NG@SiC anode shows good reversible capacity (1197.5 mAh g-1 after 200 cycles at 0.1 A g-1) and cycling durability with 76.6% capacity retention at 447.8 mAh g-1 after 1000 cycles at 10.0 A g-1. As expected, the lithium-ion full cell (LiFePO4/C//NG@SiC) shows superior rate capability and cycling stability. This interfacial interaction tailoring strategy via epitaxial growth method provides new opportunities for traditional SiC-based anodes to achieve high-performance lithium-ion storage and beyond.

Electronic Structures of Penta-SiC2 and g-SiC3 Nanoribbons: A First-Principles Study

The dimensions of nanoribbons have a significant impact on their material properties. In the fields of optoelectronics and spintronics, one-dimensional nanoribbons exhibit distinct advantages due to their low-dimensional and quantum restrictions. Novel structures can be formed by combining silicon and carbon at different stoichiometric ratios. Using density functional theory, we thoroughly explored the electronic structure properties of two kinds of silicon-carbon nanoribbons (penta-SiC₂ and g-SiC₃ nanoribbons) with different widths and edge conditions. Our study reveals that the electronic properties of penta-SiC₂ and g-SiC₃ nanoribbons are closely related to their width and orientation. Specifically, one type of penta-SiC₂ nanoribbons exhibits antiferromagnetic semiconductor characteristics, two types of penta-SiC₂ nanoribbons have moderate band gaps, and the band gap of armchair g-SiC₃ nanoribbons oscillates in three dimensions with the width of the nanoribbon. Notably, zigzag g-SiC₃ nanoribbons exhibit excellent conductivity, high theoretical capacity (1421 mA h g^-1), moderate open circuit voltage (0.27 V), and low diffusion barriers (0.09 eV), making them a promising candidate for high storage capacity electrode material in lithium-ion batteries. Our analysis provides a theoretical basis for exploring the potential of these nanoribbons in electronic and optoelectronic devices as well as high-performance batteries.

Reversing silicon carbide into 1D silicon nanowires and graphene-like structures using a dynamic magnetic flux template

A dynamic magnetic flux template (DMT) method was developed to reverse silicon carbide (SiC) into amorphous silicon nanowires (a-SiNWs) and graphene-like structures driven by both heating and a dynamic magnetic field. The DMT served as a growth template for silicon nanowires, exhibiting an elongated life-time as an anode in a Li-ion battery.

Iron vacancies engineering of FexC@NC hybrids toward enhanced lithium-ion storage properties

Defect engineering have profound influence on the energy storage properties of electrode hybrids by adjusting their intrinsic electronic characteristics. For iron carbide based materials, however, the effect of defect (especially cation vacancies) toward their electrochemical performance are still unclear. Herein, the feasible and scalable synthesis of Fe_xC@NC with 3D honeycomb-like carbon architecture and abundant Fe vacancies via template etching is reported. Such structure enable outstanding lithium-ion storage properties owing to hierarchical pores, improved intrinsic electrochemical activity, as well as the introduction of more active sites. As a result, the Fe_xC@NC-2 presents a high reversible specific capacity of 1079 mAh g^-1after 1000 cycles. Moreover, an excellent cycling stability can be achieved via maintaining a high-capacity retention (689 mAh g^-1, 98.4%) over 1000 cycles at 5 A g^-1. This study provides a feasible strategy for developing high-performance hybrids with hierarchical pore and rich defects structures.

Surface Modification and Functional Structure Space Design to Improve the Cycle Stability of Silicon Based Materials as Anode of Lithium Ion Batteries

Silicon anode is considered as one of the candidates for graphite replacement due to its highest known theoretical capacity and abundant reserve on earth. However, poor cycling stability resulted from the “volume effect” in the continuous charge-discharge processes become the biggest barrier limiting silicon anodes development. To avoid the resultant damage to the silicon structure, some achievements have been made through constructing the structured space and pore design, and the cycling stability of the silicon anode has been improved. Here, progresses on designing nanostructured materials, constructing buffered spaces, and modifying surfaces/interfaces are mainly discussed and commented from spatial structure and pore generation for volumetric stress alleviation, ions transport, and electrons transfer improvement to screen out the most effective optimization strategies for development of silicon based anode materials with good property.

Interface Engineering of Silicon and Carbon by Forming a Graded Protective Sheath for High-Capacity and Long-Durable Lithium-Ion Batteries

Silicon is one of the most promising anode materials for lithium-ion batteries, whereas its low electronic conductivity and huge volumetric expansion upon lithiation strongly influence its prospective applications. Herein, we develop a facile method to introduce a graded protective sheath onto the surface of Si nanoparticles by utilizing lignin as the carbon source and Ni(NO₃)₂ as the auxiliary agent. Interestingly, the protective sheath is composed of NiSi₂, SiC, and C from the interior to the exterior, thereby guaranteeing excellent compatibility between the neighboring components. Thanks to this unique coating layer, the obtained nanocomposite delivers a large reversible specific capacity (1586.3 mAh g^-1 at 0.2 A g^-1), excellent rate capability (879.4 mAh g^-1 at 5 A g^-1), and superior cyclability (88.2% capacity retention after 500 cycles at 1 A g^-1). Such great performances are found to derive from a slight volumetric expansion, high Li⁺ ion diffusion coefficients, good interface stability, and fast electrochemical kinetics. These properties are obviously superior to those of their counterparts, benefiting from the interface engineering. This study offers new insights into constructing high-capacity and long-durable electrode materials for energy storage.

Scalable Synthesis of Hollow β-SiC/Si Anodes via Selective Thermal Oxidation for Lithium-Ion Batteries

Silicon for anodes in lithium-ion batteries has received much attention owing to its superior specific capacity. There has been a rapid increase of research related to void engineering to address the silicon failure mechanism stemming from the massive volume change during (dis)charging in the past decade. Nevertheless, conventional synthetic methods require complex synthetic procedures and toxic reagents to form a void space, so they have an obvious limitation to reach practical application. Here, we introduce SiC_x consisting of nanocrystallite Si embedded in the inactive matrix of β-SiC to fabricate various types of void structures using thermal etching with a scalable one-pot CVD method. The structural features of SiC_x make the carbonaceous template possible to be etched selectively without Si oxidation at high temperature with an air atmosphere. Furthermore, bottom-up gas phase synthesis of SiC_x ensures atomically identical structural features (e.g., homogeneously distributed Si and β-SiC) regardless of different types of sacrificial templates. For these reasons, various types of SiC_x hollow structures having shells, tubes, and sheets can be synthesized by simply employing different morphologies of the carbon template. As a result, the morphological effect of different hollow structures can be deeply investigated as well as the free volume effect originating from void engineering from both a electrochemical and computational point of view. In terms of selective thermal oxidation, the SiC_x hollow shell achieves a much higher initial Coulombic efficiency (>89%) than that of the Si hollow shell (65%) because of its nonoxidative property originating from structural characteristics of SiC_x during thermal etching. Moreover, the findings based on the clearly observed different electrochemical features between half-cell and full-cell configuration give insight into further Si anode research.

A novel 3D porous pseudographite/Si/Ni composite anode material fabricated by a facile method

A novel 3D porous pseudographite/Si/Ni (PG/Si/Ni) composite was prepared by a facile low-temperature calcination method using saturable starch and NiCl₂·6H₂O as precursors. The pseudographite matrix of PG/Si/Ni was obtained from the reaction between starch and NiCl₂·6H₂O during the calcination process. Compared to the C/Si electrode, the PG/Si/Ni electrode delivers a high reversible specific capacity of 659.66 mA h g^-1 at a current density of 1 A g^-1 even after 2000 cycles. In addition, the PG/Si/Ni electrode shows superior rate performance and still maintains a high specific capacity of 1324.01 mA h g^-1 when the cycle current density returns to 0.1 A g^-1. The porous pseudographite structure is able to improve Li⁺ diffusion efficiency, reduce pulverization and lead to the formation of stable SEI layers during the cycling process. Therefore, these results suggest that the 3D porous pseudographite/Si/Ni composite is a promising novel anode material. Besides, the low-temperature synthesis method of the pseudographite matrix can be applied for further modification of carbon-based Si anode materials.

Hollow nanostructure of sea-sponge-C/SiC@SiC/C for stable Li+-storage capability

For the purpose of stable performance in energy storage systems, a new hollow nanostructure of sea-sponge-C/SiC@SiC/C (SCS/SiC@SiC/C) has been successfully fabricated by the SCS/SiC nanospheres coated with SiC/C shells through an in situ reduction process. Based on SCSs and the carbon shells, the stable hollow structures of SCS/SiC@SiC/C can contain large proportion of active SiC layers, which are adhered to both SCSs and the inner surfaces of carbon shells. Such nanostructured anode enables an excellent cycling stability with a capacity of 612 mAh/g at a current density of 0.5 A/g after 1,800 cycles, achieving an excellent stable Li⁺-storage capability.

Facile citrate gel synthesis of an antimony–carbon nanosponge with enhanced lithium storage

A unique three-dimensional antimony–carbon nanosponge was synthesized by a facile citrate gel method for enhanced lithium storage.

Modified SiO hierarchical structure materials with improved initial coulombic efficiency for advanced lithium-ion battery anodes

Silicon-based anode materials are indispensable components in developing high energy density lithium-ion batteries, yet their practical application still faces great challenges, such as large volume change during the lithiation and delithiation process that causes the pulverization of silicon particles, and continuous formation and reformation of the solid electrolyte interfaces (SEI) which results in a low initial coulombic efficiency. As an endeavor to address these problems, in this study, Si/SiO/Li₂SiO₃@C structures were prepared via a facile method using SiO, pitch powder and Li₂CO₃/PVA solution followed by annealing treatment. The Si/SiO/Li₂SiO₃@C composite shows a great improvement in lithium storage where a high discharge capacity of 1645.47 mA h g⁻¹ was delivered with the 1^st C.E. of 69.05% at 100 mA g⁻¹. These results indicate that the designed method of integrating prelithiation and carbon coating for SiO and the as-prepared macro scale Si/SiO/Li₂SiO₃@C structures are practical for implementation in lithium-ion battery technology.

A simple method of prelithiation of SiO along with carbon coating to achieve high performance SiO-based materials.

Si nanoparticles embedded in 3D carbon framework constructed by sulfur-doped carbon fibers and graphene for anode in lithium-ion battery

3D conductive network constructed with sulfur doped nanofibers and graphene that co-enhance the lithium storage property of the Si anode.

Fabrication and understanding of Cu3Si-Si@carbon@graphene nanocomposites as high-performance anodes for lithium-ion batteries

Besides silicon's low electronic conductivity, another critical issue for using silicon as the anode for lithium-ion batteries (LIBs) is the dramatic volume variation (>300%) during lithiation/delithiation processes, which can lead to rapid capacity fading and poor rate capability, thereby hampering silicon's practical applications in batteries. To mitigate these issues, herein, we report our findings on the design and understanding of a self-supported Cu₃Si-Si@carbon@graphene (Cu₃Si-SCG) nanocomposite anode. The nanocomposite is composed of Cu₃Si-Si core and carbon shell with core/shell particles uniformly encapsulated by graphene nanosheets anchored directly on a Cu foil. In this design, the carbon shell, the highly elastic graphene nanosheet, and the formed conductive and inactive Cu₃Si phase in Si serve as buffer media to suppress volume variation of Si during lithiation/delithiation processes and to facilitate the formation of a stable solid electrolyte interface (SEI) layer as well as to enable good transport kinetics. Chemomechanical simulation results quantitatively coincide with the in situ TEM observations of volume expansion and provide process details not seen in experiments. The optimized Cu₃Si-SCG nanocomposite anode exhibits good rate performance and delivers reversible capacity of 483 mA h g^-1 (based on the total weight of Cu₃Si-SCG) after 500 cycles with capacity retention of about 80% at high current density of 4 A g^-1, rendering the nanocomposite a desirable anode candidate for high-performance LIBs.

Silicon core-mesoporous shell carbon spheres as high stability lithium-ion battery anode

An innovative and simple synthesis strategy of silicon nanoparticle (Si NP) core covered by mesoporous shell carbon (MSC) structure is demonstrated. The Si core@MSC (SCMSC) composite is developed for addressing the issues for Si anode material in lithium ion batteries (LIBs) such as high volume expansion and low electrical conductivity. Significant improvement in the electrochemical performance for the SCMSC anode is observed compared with bare Si anode. The SCMSC composite delivers an initial specific capacity of 2450 mAh g^-1 at 0.166 A g^-1 with Coulombic efficiency of 99.2% for 100 cycles. Compared to bare Si anode, the SCMSC anode exhibits much higher Li storage capacity, superior cyclability, and good rate capability, highlighting the advantages of hierarchical MSC in the SCMSC structure.

Rational design and synthesis of SiC/TiC@SiOx/TiO2 porous core–shell nanostructure with excellent Li-ion storage performance

Porous SiC/TiC@TiO₂/SiO_x core–shell nanostructure can be fabricated by partial oxidation of Ti₃SiC₂-derived SiC/TiC nanostructured materials for excellent Li ion storage performance.