Silicon Monoxide Anode Research Articles

Pre-lithiation synergized with magnesiothermic reduction to enhance the performance of SiO anode for Advanced lithium-ion batteries

Due to its high theoretical specific capacity, micron-sized silicon monoxide (SiO) is regarded as one of the most competitive anode materials for lithium-ion batteries with high specific energy density. However, originating from the low initial Coulombic efficiency (ICE) and large volume expansion, its large-scale application is seriously hindered. Herein, an easy-to-implement solid-state pre-lithiation method synergized with the magnesiothermic reduction process was performed to enhance the ICE of SiO and a common bimetallic hydride was used as a prelithiation reagent. Moreover, the effects of different pre-lithiation reagent amounts on the physical and electrochemical properties of SiOx are investigated. Notably, the SiOx-LA@C composite anchored by in-situ generated LiAl(SiO3)2 shows a more stable microstructure and excellent electrochemical properties, which delivers an ultrahigh ICE of 89.4 % and an excellent initial capacity of 1864.4 mAh g−1. Furthermore, the full cells were successfully assembled by using the prepared anodes, which exhibit relatively stable cycle performance over 150 cycles. This work suggests a safe and feasible route to enhance the ICE of SiOx for the applicable SiO-based anode materials.

Sequencing-Dependent Impact of Carbon Coating on Microstructure Evolution and Electrochemical Performance of Pre-lithiated SiO Anodes: Enhanced Efficiency and Stability via Pre-Coating Strategy.

Silicon monoxide (SiO) has attracted considerable interest as anode material for lithium-ion batteries (LIBs). However, their poor initial Coulombic efficiency (ICE) and conductivity limit large-scale applications. Prelithiation and carbon-coating are common and effective strategies in industry for enhancing the electrochemical performance of SiO. However, the involved heat-treatment processes inevitably lead to coarsening of active silicon phases, posing a significant challenge in industrial applications. Herein, the differences in microstructures and electrochemical performances between prelithiated SiO with a pre-coated carbon layer (SiO@C@PLi) and SiO subjected to carbon-coating after prelithiation (SiO@PLi@C) are investigated. A preliminary carbon layer on the surface of SiO before prelithiation is found that can suppress active Si phase coarsening effectively and regulate the post-prelithiation phase content. The strategic optimization of the sequence whereprelithiation and carbon-coating processes of SiO exert a critical influence on its regulation of microstructure and electrochemical performances. As a result, SiO@C@PLi exhibits a higher ICE of 88.0%, better cycling performance and lower electrode expansion than SiO@PLi@C. The pouch-type full-cell tests demonstrate that SiO@C@PLi/Graphite||NCM811 delivers a superior capacity retention of 91% after 500 cycles. This work provides invaluable insights into industrial productions of SiO anodes through optimizing the microstructure of SiO in prelithiation and carbon-coating processes.

A Hybrid Structure to Improve Electrochemical Performance of SiO Anode Materials in Lithium-Ion Battery.

The wide utilization of lithium-ion batteries (LIBs) prompts extensive research on the anode materials with large capacity and excellent stability. Despite the attractive electrochemical properties of pure Si anodes outperforming other Si-based materials, its unsafety caused by huge volumetric expansion is commonly admitted. Silicon monoxide (SiO) anode is advantageous in mild volume fluctuation, and would be a proper alternative if the low initial columbic efficiency and conductivity can be ameliorated. Herein, a hybrid structure composed of active material SiO particles and carbon nanofibers (SiO/CNFs) is proposed as a solution. CNFs, through electrospun processes, serve as a conductive skeleton for SiO nanoparticles and enable SiO nanoparticles to be uniformly embedded in. As a result, the SiO/CNF electrochemical performance reaches a peak at 20% the mass ratio of SiO, where the retention rate reaches 73.9% after 400 cycles at a current density of 100 mA g-1, and the discharge capacity after stabilization and 100 cycles are 1.47 and 1.84 times higher than that of pure SiO, respectively. A fast lithium-ion transport rate during cycling is also demonstrated as the corresponding diffusion coefficient of the SiO/CNF reaches ~8 × 10-15 cm2 s-1. This SiO/CNF hybrid structure provides a flexible and cost-effective solution for LIBs and sheds light on alternative anode choices for industrial battery assembly.

SiO with ZSM-5 to regulate interfacial stability for fast-charging lithium-ion batteries

Silicon monoxide (SiO) anodes hold great promise for the high-energy advanced battery systems. However, their rate and cycling behavior confront rapid capacity degradation due to the sluggish charge transfer kinetic and serious volume expansion. Though different tactics mitigate this degradation, the effective strategy is still needed to further improve the charge diffusion and mass shift. Here, it is suggested that the stable and fast ion transfer channels are established and dominated by the ZSM-5, combining with PEO, which depresses the volume expansion and leads to the enhanced tolerance during cycling for the SiO anodes. The different molar ratio of ZSM-5/PEO solid state electrolyte impacts greatly the battery performance. This study conducts the interface issues and proposes the integration of ZSM-5 molecular sieve to improve the contact between the solid electrolyte PEO and electrode active material SiO. This resulted in the enhanced ion conductivity and superior hardness in comparison to the pure SiO anodes, correspondingly, an increase in the diffusion coefficient and the electronic conductivity of the fabricated SiO electrode is realized. The optimized anodes, achieves 5.0 A/g rate property with 300 cycles stable cycling and a capacity retention ratio of 82%. This study offers valuable insights into the rational design of cost-effective and high specific energy SiO-based solid-state lithium-ion batteries.

Unlocking the influence of pitch-based and acetylene-based carbon coating on the electrochemical performance of SiO anodes: bridging insights from half-cell to full-cell studies

Silicon monoxide (SiO) has garnered significant attention as a prominent candidate for high-energy-density lithium-ion batteries (LIBs) owing to its reduced volume expansion and enhanced cycling stability compared to pure silicon (Si). However, the effect of carbon layers derived from different carbon sources on the electrochemical performance of SiO in both half and full cells has not been comprehensively studied, and the industrial consensus regarding the selection of carbon sources for SiO remains elusive. Herein, a systematic comparative evaluation was conducted to analyze the physicochemical properties and electrochemical behaviors of SiO with two different carbon layers. Additionally, comprehensive assessments were carried out to investigate the electrochemical performance of SiO employing two distinct carbon coating methods in 6 Ah pouch full-cell configurations, where SiO coated acetylene-based carbon exhibits advantages in cycling stability and Li+ kinetic. In industrial SiO carbon coating processes, it is advisable to prioritize acetylene-derived carbon using chemical vapor deposition (CVD) characterized by a high degree of graphitization, enhanced electrical conductivity, and uniform surface coverage. The investigation rooted in electrochemical performance of different carbon layers on SiO in both half-cell and full-cell configurations, provides fundamental insights for the advancement of research in silicon-based anodes’ development.

Quantitative lithium substitution of carboxyl hydrogens in polyacrylic acid binder enables robust SiO electrodes with durable lithium storage stability

The design of advanced binders plays a critical role in stabilizing the cycling performance of large-volume-effect silicon monoxide (SiO) anodes. For the classic polyacrylic acid (PAA) binder, the self-association of –COOH groups in PAA leads to the formation of intramolecular and intermolecular hydrogen bonds, greatly weakening the bonding force of the binder to SiO surface. However, strengthening the binder-material interaction from the perspective of binder molecular regulation poses a significant challenge. Herein, a modified PAA-Lix (0.25 ≤ x ≤ 1) binder with prominent mechanical properties and adhesion strength is specifically synthesized for SiO anodes by quantitatively substituting the carboxylic hydrogen with lithium. The appropriate lithium substitution (x = 0.25) not only effectively increases the number of hydrogen bonds between the PAA binder and SiO surface owing to charge repulsion effect between ions, but also guarantees moderate entanglement between PAA-Lix molecular chains through the ion–dipole interaction. As such, the PAA-Li0.25/SiO electrode exhibits exceptional mechanical properties and the lowest volume change, as well as the optimum cycling (1237.3 mA h g−1 after 100 cycles at 0.1 C) and rate performance (1000.6 mA h g−1 at 1 C), significantly outperforming the electrode using pristine PAA binder. This work paves the way for quantitative regulation of binders at the molecular level.

Boosting the initial coulombic efficiency for SiO anodes through component controlling and microcrystalline size limiting regulated by carbon layer

Silicon-based anode materials are attracting considerable attention due to their high specific capacity for further improving the energy density of lithium-ion batteries (LIBs). Among them, silicon monoxide (SiO) has a good balance between high specific capacity and cycling lifespan, which is increasingly valuable in the market of lithium-ion batteries. However, its poor initial coulombic efficiency (ICE) severely impedes the commercialization of SiO. Although prelithiation and surface carbon coating are considered effective methods to reduce irreversible consumption during the initial lithiation process, the synergistic relationship between prelithiation and carbon coating has not yet been confirmed. Herein, we used LiH as solid-phase prelithiation reagent and acetylene as carbon source for carbon coating to improve the ICE as well as cyclic stability of SiO anode. Results show that the process sequence of pre-lithiation and carbon coating has a significant impact on regulating the internal lithium silicate components and the microcrystalline size of silicon and lithium silicates. A prioritizing carbon layer coating subsequent to prelithiation can achieve physical barrier effect, effectively regulating the prelithiation reaction process to refine the internal silicon and lithium silicate crystal material, and avoiding the formation of lithium-poor Li2Si2O5 phase. The obtained SOC-P sample exhibits a superior ICE of 88.1 % and a stable irreversible capacity of 842.9 mAh/g after 200 cycles. This work provides practical reference idea for solving the low initial efficiency issue of SiO anode material.

Improving the Electrochemical Performance of Sio Anode Material by Dual-Doping with Lithium and Titanium

Silicon monoxide (SiO) has been considered as a potential candidate of high capacity anode material for lithium-ion batteries; however, its low initial Coulombic efficiency (ICE) is a critical problem to overcome. Although a solid-state prelithiation method for SiO using LiH was reported to enhance ICE up to 90.5 %, there are still cycle performance issues that need to be resolved before commercial application. In this presentation, we propose SiO anode material dual-doped with lithium and titanium using metal hydrides to enhance both ICE and cycle performance. This Li-Ti dual-doped SiO material shows improved cycle performance than prelithiated SiO with LiH for up to 500 cycles without sacrificing ICE, because the TiSi2 mechanical buffer phases formed by the reaction with TiH2 accommodate the volume expansion during cycling. Li-Ti dual-doped SiO material also exhibits improved thermal stability at elevated temperatures and rate capability compared to prelithiated SiO with LiH. More detailed material and electrochemical properties of Li-Ti dual-doped SiO will be discussed further in the presentation.

TiO2/Reduced‐Graphene‐Oxide Double‐Layer‐Coated SiO as High‐Performance Anode for Lithium‐Ion Batteries

Silicon monoxide (SiO) is promising to be anode materials for next‐generation lithium‐ion batteries owing to its high capacity, but its application is hindered by the poor electrical conductivity, large volume expansion (≈150%) caused by the lithiation, and low lithium‐ion transport efficiency. Herein, TiO2/reduced graphene oxide (rGO) double‐layer‐coating strategy is proposed to solve the earlier issues. The anatase phase of TiO2 provides high mechanical strength and partial capacity in the SiO anode, and its lithiation product (LixTiO2) greatly enhances the lithium‐ion transport efficiency. The rGO coating on SiO makes a great contribution to suppressing the volume expansion of SiO particles during the lithiation and improves the electrical conductivity of SiO electrodes. The double‐layer coating strategy isolates SiO from direct contact with the electrolyte, reduces the loss of electrolyte, and improves the Coulombic efficiency of the batteries. Consequently, the TiO2/rGO double‐layer‐coated SiO composite maintains a capacity of 670 mAh g−1 after 200 cycles at 0.5 A g−1. The results indicate that the structural design of SiO@TiO2–rGO composite can solve the drawbacks of SiO and improve its cycling performance. Herein, a new route to prepare high‐performance SiO‐based anode for lithium‐ion batteries is provided.

Boosting the Cell Performance of the SiO/Cu and SiO/PPy Anodes via In-Situ Reduction/Oxidation Coating Strategies.

Silicon monoxide (SiO) has attracted great attention due to its high theoretical specific capacity as an alternative material for conventional graphite anode, but its poor electrical conductivity and irreversible side reactions at the SiO/electrolyte interface seriously reduce its cycling stability. Here, to overcome the drawbacks, the dicharged SiO anode coated with Cu coating layer is elaborately designed by in-situ reduction method. Compared with the pristine SiO anode of lithium-ion battery (293 mAh g-1 at 0.5 A g-1 after 200 cycles), the obtained SiO/Cu composite presents superior cycling stability (1206 mAh g-1 at 0.5 A g-1 after 200 cycles). The tight combination of Cu particles and SiO significantly improves the conductivity of the composite, effectively inhibits the side-reaction between the active material and electrolyte. In addition, polypyrrole-coated SiO composites are further prepared by in-situ oxidation method, which delivers a high reversible specific capacity of 1311 mAh g-1 at 0.5 A g-1 after 200 cycles. The in-situ coating strategies in this work provide a new pathway for the development and practical application of high-performance silicon-based anode.

Regulation of Si nanodomain size and its effect on electrochemical performance in prelithiated SiO anode

Silicon monoxide (SiO) is a promising anode material for lithium-ion batteries (LIBs) due to its relatively low volume change and superior cycling performance compared to silicon (Si). However, its low initial Coulombic efficiency (ICE) should be improved when the addition of SiO is higher than 5 wt% in graphite. Many prelithiation attempts have been made to improve its ICE, among which chemical prelithiation is widely used. However, the complex microstructures of prelithiated SiO (pre-SiO) hinder exploring the interconnection between microstructure and composition changes with its electrochemical performance. The size of Si nanodomains embedded in pre-SiO plays a crucial role in electrochemical performance. Herein, samples with different sizes of Si nanodomains are prepared via regulating the degree of prelithiation. Then the structure, composition evolutions and the size effect of Si nanodomains on the electrochemical performance are well investigated. The Si nanodomain size grows with the incremental prelithiation degree, leading to more capacity degradation. It is indicated that prelithiation promotes the growth of Si nanodomains and an appropriate Si nanodomain size of ∼10 nm is essential to retard volume expansion thus improving the cyclability. These results give fundamental insight into the pre-SiO for its future applications as the next-generation LIBs anodes.

Topology Optimized Prelithiated SiO Anode Materials for Lithium-Ion Batteries.

Silicon monoxide (SiO)-based materials have great potential as high-capacity anode materials for lithium-ion batteries. However, they suffer from a low initial coulombic efficiency (ICE) and poor cycle stability, which prevent their successful implementation into commercial lithium-ion batteries. Despite considerable efforts in recent decades, their low ICE and poor cycle stability cannot be resolved at the same time. Here, it is demonstrated that the topological optimization of the prelithiated SiO materials is highly effective in improving both ICE and capacity retention. Laser-assisted atom probe tomography combined with thermogravimetry and differential scanning calorimetry reveals that two exothermic reactions related to microstructural evolution are key in optimizing the domain size of the Si active phase and Li2 SiO3 buffer phase, and their topological arrangements in prelithiated SiO materials. The optimized prelithiated SiO, heat-treated at 650 °C, shows higher capacity retention of 73.4% and lower thickness changes of 68% after 300 cycles than those treated at other temperatures, with high ICE of ≈90% and reversible capacity of 1164 mAh g-1 . Such excellent electrochemical properties of the prelithiated SiO electrode originate from its optimized topological arrangement of active Si phase and Li2 SiO3 inactive buffer phase.

Improving electrode properties by sputtering Ge on SiO anode surface

Silicon monoxide (SiO) is an attractive anode material for lithium-ion batteries, but the low initial coulomb efficiency, poor conductivity, unstable cycling performance, etc. block the way to its wide applications. Various strategies have been applied to overcome these obstacles, but ended up being complicated, unsafe, or expensive. In this work, Ge was coated on a SiO anode by magnetron sputtering. The Ge coating enhances the conductivity of the SiO anode, alleviates the direct contact between electrolyte and SiO anode, thereby improving the initial coulomb efficiency and stabilizing the cycling performance. This work provides a simple yet useful idea to improve the performance of not only SiO anodes but also anodes made from other materials.

Improved electrochemical performance of silicon monoxide anode materials prompted by macroporous carbon

Improved electrochemical performance of silicon monoxide anode materials prompted by macroporous carbon

Mg2SiO4/Si-Coated Disproportionated SiO Composite Anodes with High Initial Coulombic Efficiency for Lithium Ion Batteries.

Silicon monoxide (SiO) is considered as one of the most promising anode material candidates for next-generation high-energy-density lithium ion batteries (LIBs) due to its high specific capacity and relatively lower volume expansion than that of Si. However, a large number of irreversible products are formed during the first charging and discharging process, resulting in a low initial Coulombic efficiency (ICE) of SiO. Herein, we report an economical and convenient method to increase the ICE of SiO without sacrificing its specific capacity by a solid reaction between magnesium silicide (Mg2Si) and micron-sized SiO. The reaction product (named MSO) exhibits a unique core-shell structure with uniformly distributed Mg2SiO4 and Si as the shell and disproportionated SiO as the core. MSO exhibits a superior ICE and a high reversible capacity of 81.7% and 1306.1 mAh g-1, respectively, which can be further increased to 88.7% and 1446.4 mAh g-1 after carbon coating, and improved cyclic stability compared to bare SiO. This work provides a simple yet effective strategy to address the low ICE issue of SiO anode materials to promote the practical application of SiO.

Lithium Silicates in Anode Materials for Li-Ion and Li Metal Batteries

The structural and interfacial stability of silicon-based and lithium metal anode materials is essential to their battery performance. Scientists are looking for a better inactive material to buffer strong volume change and suppress unwanted surface reactions of these anodes during cycling. Lithium silicates formed in situ during the formation cycle of silicon monoxide anode not only manage anode swelling but also avoid undesired interfacial interactions, contributing to the successful commercialization of silicon monoxide anode materials. Additionally, lithium silicates have been further utilized in the design of advanced silicon and lithium metal anodes, and the results have shown significant promise in the past few years. In this review article, we summarize the structures, electrochemical properties, and formation conditions of lithium silicates. Their applications in advanced silicon and lithium metal anode materials are also introduced.

Research Progresses on Structural Optimization and Interfacial Modification of Silicon Monoxide Anode for Lithium-Ion Battery

Research Progresses on Structural Optimization and Interfacial Modification of Silicon Monoxide Anode for Lithium-Ion Battery

Potassium Ions Regulated the Disproportionation of Silicon Monoxide Boosting Its Performance for Lithium-Ion Battery Anodes

Silicon monoxide (SiO) has captured great attention as one of the most promising anode materials due to its great cycling stability as well as high theoretical capacity. However, hindered by its low initial Coulombic efficiency, the possible large-scale application remains an urgent issue. Herein, through a facile method, potassium ions are introduced into the disproportionation process of SiO to promote the transition from amorphous SiOx into the cristobalite phase with higher crystallinity. The cristobalite phase exhibits lower reaction activity with lithium ions, which reduces the formation of lithium silicate. As a consequence, the cycling stability and the initial Coulombic efficiency (ICE) are improved. In addition, it is proved in our study that increasing the heating temperature is helpful to improve the ICE and cycling stability of SiO. This work provides a facile disproportionation method for the microstructure regulation of SiO, offering a possible avenue for the development of large-scale applications of the SiO anode.

In Situ Synthesis of Graphene‐Coated Silicon Monoxide Anodes from Coal‐Derived Humic Acid for High‐Performance Lithium‐Ion Batteries

AbstractSilicon monoxide (SiO) is attaining extensive interest amongst silicon‐based materials due to its high capacity and long cycle life; however, its low intrinsic electrical conductivity and poor coulombic efficiency strictly limit its commercial applications. Here low‐cost coal‐derived humic acid is used as a feedstock to synthesize in situ graphene‐coated disproportionated SiO (D‐SiO@G) anode with a facile method. HR‐TEM and XRD confirm the well‐coated graphene layers on a SiO surface. Scanning transmission X‐ray microscopy and X‐ray absorption near‐edge structure spectra analysis indicate that the graphene coating effectively hinders the side‐reactions between the electrolyte and SiO particles. As a result, the D‐SiO@G anode presents an initial discharge capacity of 1937.6 mAh g−1 at 0.1 A g−1 and an initial coulombic efficiency of 78.2%. High reversible capacity (1023 mAh g−1 at 2.0 A g−1), excellent cycling performance (72.4% capacity retention after 500 cycles at 2.0 A g−1), and rate capability (774 mAh g−1 at 5 A g−1) results are substantial. Full coin cells assembled with LiFePO4 electrodes and D‐SiO@G electrodes display impressive rate performance. These results indicate promising potential for practical use in high‐performance lithium‐ion batteries.

Enhanced electrochemical performance of silicon monoxide anode materials prompted by germanium

Although silicon oxide (SiO) as an anode material shows significant potential for application in lithium-ion batteries (LIBs) due to its high capacity, low cost, abundance, and adequate safety characteristics, severe capacity decay and sluggish charge transfer during discharge-charge processes limit its application. Herein, a novel strategy for preparing a ternary SiO@Pc@Ge composite has been developed using self-assembly via freeze drying and thermal melting. A robust and interconnected SiO@Pc frame provides sufficient channels for charge transfer and adequate number of pores for electrolyte infiltration. The in-situ assembled Ge nanoparticles are evenly dispersed in the SiO@Pc matrix like sesame seeds, augmenting the electrochemical activity of SiO. The SiO@Pc@Ge composite with a significant mass ratio delivers a high discharge capacity of 980.5 mA h g−1 in the initial 100 cycles at 100 mA g−1 and an excellent capacity retention of 90%, while exhibiting a superior rate capability of 627.8 mA h g−1 at 1400 mA g−1. Furthermore, the phase evolution and underlying Li storage mechanism during the charge-discharge process are further revealed via XPS and CV investigations, which indicate that the Li-ion kinetics is enhanced in the optimized samples. Our method provides novel insights into the utilization of low-cost and environmentally benign materials for fabricating high-performance energy devices through a simple and feasible procedure.