Silicon-based Anode Research Articles

Application of nanotechnology in the negative electrode of Si-based lithium-ion batteries

Modern electronics and electric cars frequently employ lithium-ion batteries (LIBs) because of their excellent energy density, safety, and environmental friendliness. The anode of LIBs is typically composed of carbon. Nevertheless, it loses a lot of energy when charging and draining. Lithium metal precipitates quickly from the surface of carbon electrodes and forms dendrites. These can pass through the diaphragm and cause short circuits inside the battery, posing a public safety risk. The advantages of the silicon-based anode are excellent safety, low operating voltage, and high theoretical specific capacity. It is among the most critical potential materials for high-energy-density lithium-ion batteries. However, its drawbacks, such as volume expansion and poor electrical conductivity, limit the development of LIBs. In recent years, the emergence of nanotechnology has well solved these problems. This paper first explains how silicon-based lithium-ion batteries work and summarizes the challenges of silicon-based anodes. Then, it explores the application of nanotechnology in silicon-based anode, including different dimensions of silicon nanomaterials. After the group, the paper analyzes the shortcomings of current research and proposes future directions.

Design of Silicon-Based Anode Materials for High Energy Density Li-Ion Batteries

Compared to other types of batteries, lithium batteries have an extremely high energy density, which means they can store more energy while maintaining a smaller size and weight. The ideal electrode material must have a high lithium ion capacity to store many lithium ions. In addition, the electrode material must have good electronic conductivity to promote lithium ions' rapid entry and exit. However, traditional carbon materials have limited theoretical specific capacity, and the transmission of lithium-ion batteries in traditional materials is limited, resulting in a significant decrease in capacity. Silicon has a theoretical capacity of up to 4200mAh/g, more than ten times the capacity of commercial graphite negative electrodes. In addition, silicon and lithium can undergo alloying reactions to form Li Si alloys, which helps improve the material's specific capacity. This article first summarizes the advantages of electric vehicles and lithium-ion batteries. Then, the benefits and challenges of using silicon-based materials as negative electrodes for lithium-ion batteries were elaborated in detail, and finally, the prospects of silicon-based materials in lithium-ion battery applications were summarized. This article has reference significance in improving the energy density of lithium-ion batteries.

Fluorine-Doping Carbon-Modified Si/SiOx to Effectively Achieve High-Performance Anode.

To address the significant challenges encountered by silicon-based anodes in high-performance lithium-ion batteries (LIBs), including poor cycling stability, low initial coulombic efficiency (ICE), and insufficient interface compatibility, this work innovatively prepares high-performance Si/SiOx@F-C composites via in situ coating fluorine-doping carbon layer on Si/SiOx surface through high-temperature pyrolysis. The Si/SiOx@F-C electrodes exhibit superior LIB performance with a high ICE of 79%, exceeding the 71% and 43% demonstrated by Si/SiOx@C and Si/SiOx, respectively. These electrodes also show excellent rate performance, maintaining a capacity of 603 mAhg-1 even under a high current density of 5000 mAg-1. Notably, the Si/SiOx@F-C electrode sustains a high reversible capacity of 829 mAh g-1 at 1000mA g-1 over 1400 cycles, and 588 mAhg-1 at 3000 mAg-1 even over 2400 cycles, capacity retention of up to 82.12%. Comprehensive characterization and analysis of the fluorine-doped carbon layer reveal its role in enhancing electrical conductivity and preventing structural degradation of the material. The abundant fluorine in the coating layer significantly increases the LiF concentration in the solid electrolyte interface (SEI) film, improving interfacial compatibility and overall lithium storage performance. This method is both straightforward and effective, providing a promising blueprint for the broader application of Si-based anodes in advanced lithium batteries.

Rational design of alginate-derived network binder for high-performance silicon-based anodes in Li-ion batteries

This study developed a novel alginate-derived network binder, SAH, to enhance the performance and stability of silicon-based anodes in lithium-ion batteries. Integrating acrylic acid and 2-hydroxyethyl acrylate with sodium alginate through a one-pot polymerization and in-situ cross-linking method, SAH effectively addresses the volumetric expansion challenges associated with silicon anodes. This innovative binder maintains the structural integrity of the silicon anode through its rigid acrylic acid component, while the flexible acrylic-2-hydroxyethyl ester serves as a dynamic buffer to enhance flexibility. Sodium alginate contributes its intrinsic beneficial properties and imparts a robust three-dimensional network structure through effective coupling, allowing the binder to accommodate silicon volume changes during battery operation. Consequently, lithium-ion batteries incorporating this binder exhibited improved stability and extended cycle life, achieving an impressive capacity retention rate of 87.3 % after 100 cycles at 0.5C. This study highlights the potential of biopolymeric materials in enhancing the functionality of silicon-based anodes, contributing to the ongoing development of high-performance energy storage technologies.

Preparation of core-shell Si/C/graphene composite for high-performance lithium-ion battery anodes

One of the important objectives for the development of enhanced lithium-ion batteries is developing high-performance silicon-based anodes with durable operational capability. Herein, a three-dimensional graphene-decorated core-shell Si/C composite is fabricated by the in-situ polymerization of organic pyrrole molecule and pyrolysis process, in which the melamine formaldehyde resin is subtly used as three-dimensional porous framework to offer abundant loading area for the uniform dispersion of active silicon nanoparticles. Meanwhile, the core-shell structure deriving from polypyrrole in the composite can effectively buffer the volume change of silicon ingredient and avoid the direct contact with the electrolyte during the cycling process, leading to the improved structural stability and electrochemical performance. The outermost layer of graphene nanosheets is designed to enhance the electrical conductivity of the electrode. As a result, the synthesized Si/C/graphene composite exhibits a high capacity and excellent cycling performance. This work reveals that combining a three-dimensional carbon substrate with a core-shell structure might be a promising solution for anode materials with obvious volume transformation.

Advances in Coating Materials for Silicon-Based Lithium-Ion Battery Anodes

Silicon anodes, which exhibit high theoretical capacity and very low operating potential, are promising as anode candidates that can satisfy the conditions currently required for secondary batteries. However, the low conductivity of silicon and the alloying/dealloying phenomena that occur during charging and discharging cause sizeable volume expansion with side reactions; moreover, various electrochemical issues result in inferior cycling performance. Therefore, many strategies have been proposed to mitigate these problems, with the most commonly used method being the use of nanosized silicon. However, this approach leads to another electrochemical limitation—that is, an increase in side reactions due to the large surface area. These problems can effectively be resolved using coating strategies. Therefore, to address the issues faced by silicon anodes in lithium-ion batteries, this review comprehensively discusses various coating materials and the related synthesis methods. In this review, the electrochemical properties of silicon-based anodes are outlined according to the application of various coating materials such as carbon, inorganic (including metal-, metal oxide-, and nitride-based) materials, and polymer. Additionally, double shells introduced using two materials for double coatings exhibit more complementary electrochemical properties than those of their single-layer counterparts. The strategy involving the application of a coating is expected to have a positive effect on the commercialization of silicon-based anodes.

Construction of WO3 nanowires artificial solid electrolyte interphase on silicon nanoparticles with sea urchin like structure for improving silicon anode stability

Giant volumetric variation of silicon during repeat lithiation/delethiation process leads to structure failure of silicon-based anodes and thus their initial high capacitance is hard to be maintained under long-run cyclic charging/discharging. Construction porous structure silicon composites and formation of artificial solid electrolyte interphase (SEI) coating on silicon particles are two effective ways to improve stability of silicon-based anodes. In this work, above two strategies are combined to construct a composite of inorganic artificial SEI WO3 nanowires/Si nanoparticles with sea urchin like porous structure via simple hydrothermal method. The silicon nanoparticles act as seeds for around 70 nm average diameter WO3 nanowires formation in compared with that of WO3 nano-rods around 500 nm diameter without Si nanoparticle seeds. The WO3 nanowire artificial SEI coating is found to be effective in preventing SEI overgrowth and their network provides spaces for volumetric variation of silicon nanoparticles in the bulk anode matrix during cyclic test, leading to reversible charging/discharging of stable bulk anode in compared with pure silicon anode of fast capacitance decay. The gravimetric capacitance of optimized composite reaches 1410.6 mAh·g−1 and its capacity remains 1039 mAh·g−1 after 200 cycles.

Polyacrylonitrile and aluminum metal dual functionalization interconnected network for superior lithium storage in silicon anode

Currently, silicon-based anode is one of the most promising anode materials that can be applied in next-generation lithium-ion batteries. However, the high activity of the electrode–electrolyte interface and low electronic conductivity of Si anode during the cycling process greatly limits its large-scale application. Aluminum (Al) is the metallic current collector known to promote electronic conductivity and lithium-ion transfer at low cost. However, to our knowledge, scalable interface engineering incorporating Al with carbonized polymer has not been reported. Herein, a polyacrylonitrile (PAN) and aluminum metal dual functionalization interconnected network is achieved via a simple sol-gel method followed by high-temperature calcination to obtain a stable solid electrolyte interphase (SEI) while allowing fast Li+ transmission. The calculated diffusion energy barrier for lithium ions in Al is 0.2198 eV, significantly lower than that in Cu and Fe. Benefiting from the enhanced interfacial protection and kinetics of Si with polyacrylonitrile/Al, the prepared Si@Al@CPAN anode exhibits high lithium storage capacity (2034.90 mAh/g after 150 cycles at 0.84 A/g). At the same time, the prepared Si@Al@CPAN anode outperforms the pure Si anode in rate performance at 12.6 A/g (1116.75 mAh/g vs. 2.84 mAh/g). The present work delivers new design ideas for high-performance Si anode with a multi-functionalization interface.

Synergistic Structural Integrity and Remarkable Structural Stability of NC@Si Anodes for Lithium-ion Batteries

The silicon-based anode has attracted wide attention because of its high theoretical specific capacity, which is expected to greatly improve the batteries’ energy density. However, during the charge-discharge cycles, the great volume expansion of the anode active silicon seriously restricts its electrochemical stability. Herein, N-doping carbon-coated silicon microsphere was prepared for lithium-ion batteries. Benefit from the core-shell structure formed from silicon carbon, the volume change of silicon anode during the cycle is well coordinated. What's more, N-doping carbon reduces the reaction energy barrier between silicon and lithium and accelerates the electrochemical reaction, which improves the cycling performance of the battery. The specific capacity of the prepared button battery is as high as 2913.13 mAh g−1 at the current density of 0.21 mA g−1, and the average coulomb efficiency is higher than 99.84% during the cycling. And the capacity of NC@SiO2 anode gradually stabilizes after 500 cycles.

Robust self-healing ion-conductive interlocking dual-network binder based on gradient dynamic bonding for advanced SiO anodes in Li-Ion batteries

Silicon-based (e.g., SiO) anodes have attracted much attention for their high specific capacity; however, poor conductivity and dramatic volume change during the charge/discharge cycling hinder their commercial application in high energy density lithium-ion batteries (LIBs). Ideal binders hold a decisive effect on inhibiting the volume effect of the silicon-based anode. Herein, inspired by the hierarchical structure of living organisms, we design a multifunctional self-healing interlocking dual-network binder based on gradient dynamic bonding and apply the binder to SiO anode toward high specific capacity and long-term cycle performance. Specifically, rigid polyacrylic acid (PAA) and flexible polylipoic acid (PTA) are interlocked by gradient dynamic bonding containing of disulfide linkage, metalcoordination and hydrogen bonding. The obtained binder has strong adhesion, high mechanical toughness, fast self-healing performance and high ionic conductivity, which enable the SiO anode effectively buffering the volume expansion and exhibiting excellent cycling stability. The SiO electrode with the new binder delivers a high capacity of 884.8 mAh/g at a current density of 0.5 A/g after 500 cycles and a high capacity of 765.2 mAh/g at a high mass loading of 3.0 mg cm−2 after 100 cycles. Moreover, the assembled SiO||NCM811 full cell achieves a reversible capacity of 169.75 mAh/g with capacity retention of 77.5 % after 100 cycles. This work offers a new method for the design of versatile self-healing binder adaptive to electrode volume change, so as to accelerate the application of the silicon-based anode.

Enhanced strain mapping Unveils internal deformation dynamics in Silicon-based lithium-ion batteries during electrochemical cycling

Silicon-based anodes have emerged as a promising advancement in lithium-ion battery technology, offering significantly higher lithium storage capacities than traditional graphite. However, the volumetric expansion of silicon—anodes can swell by up to 300 % during lithiation—presents serious challenges to their structural integrity and electrochemical stability. This study investigates the internal structural dynamics of silicon anodes during lithiation and delithiation cycles. A novel cell design for a 18,650 cylindrical cell featuring micro-sized internal speckles within the silicon anode is presented. This design improves the simulation of electrochemical conditions and allows for precise displacement tracking, mitigating impacts on capacity and cycle performance while enhancing Digital Volume Correlation (DVC) analysis. The research prioritizes reducing scan time and radiation exposure in micro-CT assessments of Li-ion cells, and improves the accuracy of internal strain mapping via DVC. Displacement fields over three charging and discharging cycles are documented. Notably, uneven volumetric changes are observed, with local displacements reaching up to 35 µm in areas smaller than 2.5 mm in radius, which contracted during charging and expanded during discharging. This protocol offers insights into the relationship between electrode mechanics and cell performance, promoting non-destructive evaluations of internal structures in commercial cells.

Carbon-encapsulated silicon ordered nanofiber membranes as high-performance anode material for lithium-ion batteries

Silicon have attracted much attention as a promising anode material for lithium-ion batteries due to the extremely high theoretical capacity. However, its practical application is limited by the huge volume expansion during the cycling process. To address this issue, carbon-encapsulated silicon ordered nanofiber membranes were designed through a modified electrospinning technology with a strong magnetic field. Compared with the conventional nanofiber membranes, the optimized M1200 Gs anode exhibited a high discharge capacity of 1603.1 mAh·g−1 at 0.1 A·g−1, a superior rate performance, and a robust cycling stability with a reversible capacity of 658.1 mAh·g−1 at 1 A·g−1 after 100 cycles. The improved electrochemical performance was confirmed to be highly correlated with the parallel structure of nanofibers, which help to facilitate the diffusion and transport of electrons and ions, realize the stress distribution and buffer the volume changes. This work provides unique insights into designing silicon-based anodes with novel structures for lithium-ion batteries.

Selective Methylation of Cyclic Ether Towards Highly Elastic Solid Electrolyte Interphase for Silicon-based Anodes.

Silicon (Si)-based anodes offer high theoretical capacity for lithium-ion batteries but suffer from severe volume changes and continuous solid electrolyte interphase (SEI) degradation. Here, we address these challenges by selective methylation of 1,3-dioxolane (DOL), thus shifting the unstable bulk polymerization to controlled interfacial reactions and resulting in a highly elastic SEI. Comparative studies of 2-methyl-1,3-dioxolane (2MDOL) and 4-methyl-1,3-dioxolane (4MDOL) reveal that 4MDOL, with its larger ring strain and more stable radical intermediates due to hyperconjugation effect, promotes the formation of high-molecular-weight polymeric species at the electrode-electrolyte interface. This elastic, polymer-rich SEI effectively accommodates volume changes of Si and inhibits continuous side reactions. Our designed electrolyte enables Si-based anode to achieve 85.4% capacity retention after 400 cycles at 0.5 C without additives, significantly outperforming conventional carbonate-based electrolytes. Full cells also demonstrate stable long-term cycling. This work provides new insights into molecular-level electrolyte design for high-performance Si anodes, offering a promising pathway toward next-generation lithium-ion batteries with enhanced energy density and longevity.

Biological small molecule interface-modification fostering resilient interfacial chemistry for silicon-based anodes

Silicon-based materials, particularly at the microscale, are prone to rapid capacity fade due to substantial volume fluctuations during the charge-discharge cycles, significantly impeding their commercial viability. Constructing a stable solid electrolyte interface (SEI) is an effective means to improve the performances of silicon-based anodes. Here small biomolecules, tryptophan (Trp) and phytic acid (PA), are introduced as interface modifiers to optimize the interfacial chemistry of micron-silicon anodes. By engaging in the SEI formation process, these small biomolecules effectively regulate the chemical composition and mechanical properties of the formed SEI, fostering a more cohesive and durable interface. The simultaneous addition of PA and Trp has been observed to yield a synergistic effect, creating a tightly bonded and resilient SEI that confers markedly improved battery performances upon the co-modified micron silicon anodes. Density functional theory calculations reveal charge interactions between these small biomolecules and silicon particles, facilitating effective adsorption onto the silicon surface. Simultaneous adsorption of Trp and PA on silicon surface can significantly enhance adsorption strength, providing a compelling explanation for the observed synergistic effect of Trp and PA co-modification.

Modulation of Free Carbon Structures in Polysiloxane-Derived Ceramics for Anode Materials in Lithium-Ion Batteries.

Polymer-derived silicon oxycarbide (SiOC) ceramics have garnered significant attention as novel silicon-based anode materials. However, the low conductivity of SiOC ceramics is a limiting factor, reducing both their rate capability and cycling stability. Therefore, controlling the free carbon content and its degree of graphitization within SiOC is crucial for determining battery performance. In this study, we regulated the free carbon content using divinylbenzene (DVB) and controlled the graphitization of free carbon with the transition metal iron (Fe). Through a simple pyrolysis process, we synthesized SiOC ceramic materials (CF) and investigated the impact of Fe-induced changes in the carbon phase and the amorphous SiOC phase on the comprehensive electrochemical performance. The results demonstrated that increasing the DVB content in the SiOC precursor enhanced the free carbon content, while the addition of Fe promoted the graphitization of free carbon and induced the formation of carbon nanotubes (CNTs). The electrochemical performance results showed that the CF electrode material exhibited a high reversible capacity of approximately 1154.05 mAh g-1 at a low current density of 100 mA g-1 and maintained good rate capability and cycling stability after 1000 cycles at a high current density of 2000 mA g-1.

The Synergistic Effect of Cross-Linked and Electrostatic Self-Assembly Si/MXene Composites Anode for Highly Efficient Lithium-Ion Battery

Silicon is a promising anode material for high-performance lithium-ion batteries (LIBs), but its rapid capacity degradation has significantly hindered its large-scale application. In this study, we propose an in situ self-assembly polymerization method to fabricate a stable silicon-based anode by leveraging electrostatic self-assembly technology, in situ esterification, and amidation reactions. The incorporation of a cross-linked polymer, combined with the synergistic effects of electrostatic interactions between negatively charged MXene and positively charged silane-coupling-agent-modified silicon, offers a novel strategy for enhancing the electrochemical performance of LIBs. Notably, annealed electrodes with a 65 wt% nmSi-NH2/MXene ratio demonstrate outstanding electrochemical performance, achieving a capacity of 929.5 mAh g⁻¹ at a current density of 1 A g⁻¹ after 100 charge/discharge cycles. These findings suggest that the integration of cross-linked polymers and electrostatic self-assembly can significantly improve the intercalation and overall electrochemical performance of silicon anodes in lithium-ion batteries.

Preparation of Si/TiSi2 as high-performance anode material for lithium-ion batteries by molten salt electrolysis

The photovoltaic industry has generated a large amount of silicon cutting waste (SiCW), whose disposal presents an urgent environmental issue. In this study, micron-sized flaky silicon cutting waste was transformed into silicon nanowires, and Si/TiSi2 nanocomposites were synthesized through molten salt electrolysis using photovoltaic SiCW and TiO2 as precursors. Lithium-ion batteries using the resulting composites as an anode exhibited an initial discharge specific capacity of 1936.1 mAh g⁻¹ and an initial Coulombic efficiency (ICE) of 83.99 %. After 200 cycles, its reversible specific capacity reached 1133.8 mAh g⁻¹, surpassing that of the molten salt electrolytic pre-oxidized SiCW (535.5 mAh g⁻¹) and untreated SiCW (385.0 mAh g⁻¹). This study presents a novel approach for modifying silicon-based anode materials while offering a sustainable and environmentally friendly method for recycling photovoltaic silicon waste.

Control of N/P ratios and cut-off voltage for Silicon-Based Li-ion batteries

High-energy density and unwavering safety standards form the cornerstone of new energy vehicle development, necessitating the design of power batteries that seamlessly integrate these critical qualities. Key to this endeavor is the enhancement of energy density at the architectural level, focusing on the optimization of the N/P ratio—a move that demands a holistic evaluation extending beyond mere comparisons of cathode and anode capacities to include initial efficiency, and both reversible and irreversible capacities. Departing from traditional N/P ratio designs requires meticulous optimization. This research introduces a novel N/P ratio design methodology, termed the “Water Cup Model”, for lithium-ion batteries (LIBs), effectively addressing capacity loss issues endemic to conventional designs. This approach, under consistent cathode material and areal capacity conditions, increases the batteries’ specific energy by approximately 5 Wh/kg, without compromising safety. Further innovation is achieved by incorporating a voltage regulation coefficient, λ, allowing for precise adjustment of the cut-off discharge voltage and facilitating the selection of high-performance silicon-based anode materials. Comparative assessments of energy density and cycling performance affirm the superiority of our optimized N/P ratio strategy against conventional methods. This strategy’s core lies in its capacity to significantly boost energy density without extensive modifications to the battery’s internal makeup, relying solely on the precise management of the N/P ratio to ensure safety is not compromised by energy density enhancements. This seminal work lays down a cost-effective, robust framework for advancing high-performance LIB technology, contributing pivotal insights to the field.

Silicon/graphite/amorphous carbon composites as anode materials for lithium-ion battery with enhanced electrochemical performances

Silicon has emerged as one of the most promising anode materials for next-generation lithium-ion batteries due to its exceptional specific capacity and abundant resources. However, its widespread application is hindered by structural deformability and low intrinsic conductivity. By strategically integrating a conductive carbon matrix with silicon, it becomes feasible and efficient to enhance the electrical conductivity of silicon and accommodate the stress-induced volume expansion during battery operation. In this study, a series of silicon/graphite/amorphous carbon (Si/G/C) composites were prepared using mechanical milling and carbothermal reduction. The study focused on two main aspects: the effect of the ratio of micro-sized silicon to flake graphite on the properties of the composite and the compatibility of different-scale silicon particles (micro-sized silicon and nano-sized silicon) and different kinds of natural graphite (flake graphite and cryptocrystalline graphite). The results reveal that when micro-sized silicon and flake graphite are combined, the graphite is fragmented more thoroughly, resulting in smoother surfaces and reduced aggregation of secondary particles. The composites with a mass ratio of 7:3 micro-sized silicon to flake graphite have the smallest specific surface area and pore size, homogeneous distribution, and stable structure. This exceptional carbon-to-silicon ratio endows the Si/G/C composite with rapid reaction kinetics, enabling a specific discharge capacity of 854.1 mAh g-1 after 200 cycles at 1A g-1. The findings offer valuable insights into the design and optimization of silicon-based anode materials for next-generation lithium-ion batteries.

High-Branched Natural Polysaccharide Flaxseed Gum Binder for Silicon-Based Lithium-Ion Batteries with High Capacity.

Silicon-based anodes heavily depend on the binder to preserve the unbroken electrode structure. In the present work, natural flaxseed gum (FG) is used as a binder of silicon nanoparticles (SiNPs) anode for the first time. Owing to a large number of polar groups and a rich branched structure, this material not only anchors tightly to the surface of SiNPs through bonding interactions but also formed a hydrogen bonding network structure among molecules. As a result, the FG binder can endow the silicon electrode with stable interfacial adhesion and outstanding mechanical properties. In addition, FG with a high viscosity facilitates the homogeneous dispersion of the electrode components. When FG is used as a binder, the cycling performance of the Si anode is greatly improved. After one hundred cycles at an applied current density of 1 A g-1, the electrode continues to display remarkable electrochemical properties with a significant cyclic capacity (2213mAh g-1) and initial Coulombic efficiency (ICE) of 89.7%.