SiOx Particles Research Articles

Creation of high-fluence precursors by 351-nm laser exposure on SiO2 substrates

The onset of laser-induced damage on the exit surface of fused silica optics when exposed to UV ns pulses is a limiting factor in the design and operation of most high-energy laser systems. As such, significant effort has been expended in developing laser damage testing protocols and procedures to inform laser system design and operating limits. These tests typically rely on multiple laser exposures for statistical validation. For large aperture systems, testing an area equal to that of the optical components in the system is functionally impossible; instead, sub-scale witness samples are interrogated with elevated fluences. We show that, under certain circumstances, the laser exposure used to test one location on a sample will generate additional, laser-induced damage precursors in regions beyond that exposed to laser light and hence degrade the damage performance observed on subsequent exposures. We hypothesize the precursors result from condensation of vaporized silica, which re-condenses as SiOx particles deposited on the exit surface. In addition, we will outline the conditions under which this phenomenon occurs, as well as methods for mitigating or eliminating the effect.

Microstructural Tuning of Silicon-Based Anodes and Their Stress Evolution during Electrochemical Cycling

Composite electrodes that incorporate oxidized silicon are a cost-effective way to accommodate stresses and extend cycle life. To obtain fundamental information about chemo-mechanical phenomena in these composite structures, several different types of materials are being investigated through tuning the microstructures of Si nanoparticles and composite SiOx particles. The evolution of internal stresses in all of these structures was monitored with precise in situ curvature in conjunction with parallel electrochemical measurements. Ex situ characterization with electron microscopy, x-ray diffraction, and XPS provide important complementary information about changes in the materials. The different types of materials used for this work make it possible to systematically investigate key length scales, by independently varying the microstructures such as oxide layer thicknesses and particle/nano-cluster sizes. Analysis of these results requires assessments and models of both the chemical and mechanical effects of oxide surface layers and silicon encapsulation. The implications for optimizing these composite electrode structures will also be presented.

An integral interface with dynamically stable evolution on micron-sized SiOx particle anode

Abstract Micron-sized SiOx particles, owing to their distinct advantages in energy density, processability and cost, have shown promises in Li-ion batteries. However, the huge volume variation of micron-SiOx raises many issues including overgrowth of solid electrolyte interphase (SEI) and pulverization of bulk, which accounts for continuously faded storage performance during repeated Li uptake/release. To address above problems, we propose to stabilize the electrochemistry of micron-SiOx by building an integral interface with dynamically stable evolution on carbon-coated SiOx particles. The interface consists of Li polyacrylate nanolayer interfused with multiwalled carbon nanotubes. Both highly stretchable components maintain the structural integrity of micron-SiOx particles upon volume variation and coalesce the secondary particles in case pulverization occurs. The interface also enables injection of Li+/e– into micron-SiOx for sustaining the (de)lithiation, while restrains the overgrowth of SEI. Micron-SiOx particles protected by the integral interface have demonstrated, both in Li half and full cells, improved lithium storage properties in terms of capacity output and retention, Coulombic efficiency and rate capabilities. With this work, we tend to offer insights on interfacial engineering of micron-sized electrode materials with unstable chemical or structural evolution in practical batteries.

An ultrahigh-areal-capacity SiOx negative electrode for lithium ion batteries

Constructing a stable microstructure is highly crucial in promoting the practical applications of Si-based negative electrodes, addressing the issues of huge volume change and unstable solid electrolyte interface (SEI). Herein, an integrated electrode structure is developed based on micro-sized SiOx particles by bilayers coating of carbon and poly(3,4-ethylene dioxythiophene) (PEDOT) with carbon nanotube/Super P conductive network in-situ embedded (SiOx@C@P_CS). The as-prepared SiOx@C@P_CS negative electrode exhibits high Coulombic efficiency reaching 99.9% and capacity retentions of 86.7% (1019 mAh g−1) after 1000 cycles at 750 mA g−1 and 98.4% (973 mAh g−1) after 400 cycles at 1500 mA g−1 (with a commercial-level areal capacity of 2.57 mAh cm−2). The excellent long cycling capability is further evidenced both in half cell with ultrahigh areal capacity up to 11.75 mAh cm−2 at the mass loading of 8.66 mg cm−2 and Li[Ni0.8Co0.1Mn0.1]O2 (NCM811)||SiOx@C@P_CS full cell with commercial loading. The improved electrochemical performance is attributed to the synergistic effects of the bilayers. This study offers a facile solution to the challenges facing alloying-type negative electrode materials with huge volume changes by confining volume change, enhancing electric conductivity, and isolating the growth of SEI to promote their practical uses.

One-Step Synthesis of SiOx@Graphene Composite Material by a Hydrothermal Method for Lithium-Ion Battery Anodes

SiOx@graphene composite material was prepared by a one-step hydrothermal method and was used as a high-performance anode material for lithium-ion batteries. Graphene decoration on SiOx particles ca...

A study of CNT fiber-reinforced multi-carbon resource-coated SiOx composite as anode materials

To enhance the cycling and rate performances of SiO as an anode material, a CNT fiber-reinforced multi-carbon resource-coated SiOx composite (SiOx@MC/CNTs) prepared via a two-step pyrolysis process is evaluated. The SiOx@MC/CNTs composite exhibits a high initial coulombic efficiency of 74.6%, an initial charge capacity of 1400.5 mAh/g, and an initial discharge capacity of 1878.6 mAh/g. After 250 cycles, the composite shows a reversible capacity of 992.9 mAh/g, with a capacity retention rate of 70.9%. In addition, the composite obtains a good rate performance for the discharge capacities of 1381.3 mAh/g at 0.5 A/g and 1328.1 mAh/g at 1.0 A/g. The improved properties should be ascribed to the amorphous carbon layer and the CNT addition. The carbon layer prevents SiOx surface from direct contacting the electrolyte and adapts the volume change of SiOx particles during the repeated lithiation/delithiation process. The composite exhibits high conductivity of 4637.8 S/cm which is seven times higher than SiOx without the amorphous carbon layer and CNTs. This fabricating process can be a reference for the preparation of SiOx anode materials.

Rational structure design to realize high-performance SiOx@C anode material for lithium ion batteries

Silicon suboxide (SiOx) is considered to be one of the most promising materials for next-generation anode due to its high energy density. For its preparation, the wet-chemistry method is a cost-effective and readily scalable route, while the so-derived SiOx usually shows lower capacity compared with that prepared by high temperature-vacuum evaporation route. Herein, we present an elaborate particle structure design to realize the wet-chemistry preparation of a high-performance SiOx/C nanocomposite. Dandelionlike highly porous SiOx particle coated with conformal carbon layer is designed and prepared. The highly-porous SiOx skeleton provides plenty specific surface for intimate contact with carbon layer to allow a deep reduction of SiOx to a low O/Si ratio at relatively low temperature (700 °C), enabling a high specific capacity. The abundant mesoscale voids effectively accommodate the volume variation of SiOx skeleton, ensuring the high structural stability of SiOx@C during lithiation/delithiation process. Meanwhile, the three-dimensional (3D) conformal carbon layer provides a fast electron/ion transportation, allowing an enhanced electrode reaction kinetics. Owing to the optimized O/Si ratio and well-engineered structure, the prepared SiOx@C electrode delivers an ultra-high capacity (1,115.8 mAh·g−1 at 0.1 A·g−1 after 200 cycles) and ultra-long lifespan (635 mAh·g−1 at 2 A·g−1 after 1,000 cycles). To the best of our knowledge, the achieved combination of ultra-high specific capacity and ultra-long cycling life is unprecedented.

Rice husk-derived SiOx@carbon nanocomposites as a high-performance bifunctional electrode for rechargeable batteries

This paper we use ZnCl2 to activates and reduces rice husks to produce SiOx@N-doped carbon core-shell nanocomposites with inner voids is a facile and effective strategy to improve the electrochemical performance. As an anode material for the lithium-ion batteries, the composites exhibit a high reversible capacity (1315 mAh g−1 after 100 cycles at 100 mA g−1) and long-term stability (584 mAh g−1 after 500 cycles at 500 mA g−1). Such outstanding cycling stability is attributed to the small size of the SiOx particles with inner voids and the carbon layer coating can guarantee good structural integrity for long cycle stability. As a cathode material for Li–S batteries, the composite displays a high capacity and good stability (675 mAh g−1 after 100 cycles at 0.1C). Its good performance and facile preparation will improve the utilization of rice husk waste.

Volume expansion restriction effects of thick TiO2/C hybrid coatings on micro-sized SiOx anode materials

In this work, novel SiOx anode materials with low volume expansion and high ionic/electrical conductivity are designed by combining internal buffer space and external super thick TiO2/C hybrid shell of 200–400 nm. An electrochemical reaction visualizing confocal system is originally developed for characterizing electrode thickness changes, and the real-time quantitative change of electrode thickness during charging and discharging is realized. Surprisingly, the maximum thickness expansion of designed anodes with the specific capacity of 1006.2 mA h g−1 is only 37% in the first lithiation process. Subsequently, the designed anodes present stable cycle life of the capacity attenuation of 7.83% after 100 cycles compared with the capacity of 5th cycle. It demonstrates that the designed thick TiO2/C hybrid coatings effectively swing the expansion stress of micro-sized SiOx to internal space. This work proves that the huge volume expansion of micro-sized SiOx particles can be controlled by reasonable design of surface hybrid coatings and bulk structure, and the long lifespan can be maintained. This strategy paves a way for the development of micro-sized SiOx anode materials with long cycle life and good process ability for high energy density lithium-ion batteries.

Facile, economical and environment-friendly synthesis process of porous N-doped carbon/SiOx composite from rice husks as high-property anode for Li-ion batteries

To enhance electrochemical properties of C/SiOx composite for business application, N-doped carbon/SiOx composite has been successfully fabricated using rice husks as the raw material of both C and Si sources and urea as N source via an environmentally friendly and economically viable strategy. The obtained N@C/SiOx composite exhibits a porous irregular particle morphology with a high specific surface area. SiOx particles are uniformly dispersed in N-doped C skeleton. As an anode material for Li-ion batteries, the porous structure, N doping and high reduction degree of SiO2 endow N@C/SiOx electrodes with an outstanding reversible capacity up to 1018.5 mAh/g at 0.1 A/g and a remarkable initial coulombic efficiency of 72.2%, which is larger than that of carbonized rice husks (45.7%). Even if the current density rises to 1.0 A/g, the reversible specific capacity can maintain at 623.3 mAh/g with a capacity degradation of merely 4.0% after 1000 cycles.

Controllable Synthesis of Carbon-Coated SiOx Particles through a Simultaneous Reaction between the Hydrolysis-Condensation of Tetramethyl Orthosilicate and the Polymerization of 3-Aminophenol.

Core-shell particles are desirable for many applications, but the precise design and control of their structure remains a great challenge. In this work, we developed a strategy to fabricate carbon-coated SiOx (SiOx@C) core-shell particles via a sol-gel method using the simultaneous hydrolysis-condensation of tetramethyl orthosilicate (TMOS), the polymerization of 3-aminophenol and formaldehyde in the presence of ammonia as a basic catalyst, and cetyltrimethylammonium bromide (CTAB) as a cationic surfactant in the mixed solution of water and methanol followed by the carbonization process. Results from this study provide new insight into the design of core-shell particles by using TMOS as an effective silica precursor for the first time with a well-controlled reaction rate and spherical morphology. To obtain an in-depth understanding of the formation of core-shell structure, a possible mechanism is also proposed in this article. When tested as an anode material for lithium ion batteries (LIBs), the obtained SiOx@C particles delivered a reversible capacity of 509.2 mAh g-1 at a current density of 100 mA g-1. This electrochemical performance is significantly better than those of similar composites without the core-shell structure. The capacity retention after 100 cycles was approximately 80%. These results suggest great promise for the proposed SiOx@C particles with core-shell structure, which may have potential applications in the improvement of various energy-storage materials.

Possibility of Recycling SiOx Particles Collected at Silicon Ingot Production Process as an Anode Material for Lithium Ion Batteries

Recently, some studies have utilized silicon (Si) as an anode material of lithium ion battery by recycling Si from the slurry of wafer slicing dust. The filtration of Si particles condensed from Si vapors that were exhausted from the ingot growing furnace could propose another method of Si recycling. In this study, we investigated the possibility of using such collected silicon oxides (SiOx) particles as an anode material. After collecting SiOx particles, FE-SEM, TEM, EDS, XRD, XPS analysis, and charge/discharge test were carried out to investigate characteristics and usability of these particles. FE-SEM and FE-TEM images showed that these particles mainly consisted of spherical primary particles with a diameter of 10 nm or less. Agglomerates of these primary particles were larger than 300 nm in diameter. In TEM image and EDS analysis, crystalline particles were observed along with amorphous particles. As a result of XRD analysis, amorphous silica (SiO2) and crystalline Si were observed. Charge/discharge tests were carried out to determine the feasibility of using these particles as an anode material for lithium ion batteries. A cycle efficiency of 40.6% was obtained in the test in which the total number of charge/discharge cycle was 100 under the condition of C-rate 0.2 for the first three times and C-rate 1.0 for the remaining 97 times. Results showed that these collected particles could be used as an anode material for lithium ion batteries.

Scalable in situ condensation fabrication of amorphous SiOX@C microbeads derived from organic silane coupling agents for lithium-ion storage

In the past few years, silane coupling agents are often used to modify the surface of silicon materials; however, researches in preparation of SiOX-based materials pyrolyzed from silane coupling agents are seldom reported. Hence, in order to prepare amorphous SiOX@C anodes for Li-ion storage, we adopted three kinds of silane coupling agents as organic silicon sources. The results show that silane coupling agents with vinyl group is the optimum organic silicon source. Owing to the strong chemical bonds of Si–O–C, amorphous SiOX particles are uniformly embedded in carbon matrix, forming monodisperse microbeads architecture with good buffer abilities. Therefore, the V-SiOX@C anodes derived from silane coupling agents with vinyl groups show good electrochemical performance, retaining a reversible discharge capacity of 940 mAh g−1 at a current density of 100 mA g−1 after 200 cycles, and it still depicts a good long-term cycling durability, maintaining 739 mAh g−1 at a current density of 400 mA g−1 after 400 cycles.

Uniform SiOx/graphene composite materials for lithium ion battery anodes

Multilayer graphene is prepared by micromechanical exfoliation method. Then, it is used as conductive component for lithium ion battery SiOx anodes. Uniform SiOx/graphene composite materials with different percentages of graphene are obtained by high-energy ball milling process. The multilayer graphene can connect the SiOx particles and enhance the electrical conductivity effectively. The optimized SiOx/graphene composite electrode exhibits excellent electrochemical performance with initial reversible specific capacity of 1325.7 mAhg−1 and capacity retention as high as 95.8% (1269.7 mAhg−1) after 120 cycles. The mechanical exfoliation approach used for the production of multilayer graphene is low-cost, mass-productive and effective in SiOx conductivity enhancement. The excellent conductive agent of multilayer graphene could be employed for high-performance lithium ion battery SiOx anodes.

Three-Dimensional Rigidity-Reinforced SiOx Anodes with Stabilized Performance Using an Aqueous Multicomponent Binder Technology

Three-dimensional (3D) rigidity-reinforced SiOx anodes are prepared using the aqueous multicomponent binders to stabilize the performances of lithium-ion batteries. Considering an elastic skeleton, adhesiveness, electrolyte absorption, etc., four kinds of binders [polyacrylamide (PAM), poly(tetrafluoroethylene) (PTFE), carboxymethyl cellulose, and styrene butadiene rubber (SBR)] are selected to prepare aqueous multicomponent binders. The SiOx anodes with the binder PAM/SBR/PTFE (PSP) exhibit a 3D rigidity-reinforced structure, larger adhesive force, and moderate electrolyte adsorption capacity compared to other anodes with single and multicomponent binders. Specifically, the electrochemical performances of the SiOx anodes with the binder PSP663 are stabilized, and a retention capacity of 770 mAh g-1 at 500 mA g-1 after 300 cycles and a rate capacity of 993 mAh g-1 at 1200 mA g-1 are obtained. The enhanced performances are attributed to the good chemical stability of PTFE to protect SiOx particles from the electrolyte corrosion and to ensure electrode integrity. SBR acts as the binder backbone due to the strong adhesion force and specific three-dimensional structure. The rigidity of PAM limits the excessive expansion of SiOx particles well and shortens the ion migration. These results indicate that the 3D rigidity-reinforced SiOx anode with the aqueous binder PSP663 has promising prospects for practical application, and the results also provide a reference for solving the expansion problem of the silicon materials.

Efficient modification of Si/SiOx nanoparticles by pulse-modulated plasma flash evaporation for an improved capacity of lithium-ion storage

Composite Si/SiOz nanoparticles have been produced from SiO powder feedstock by pulse-modulated plasma flash evaporation (PFE) and the effect on the lithium-ion battery properties are analyzed. With the introduction of power and powder-feeding pulse-modulation during PFE, the primary SiOx particle size decreases from 27.9 to 14.3 nm and the core crystalline Si is reduced from 14.2 to 7.3 nm. Although no appreciable reduction in the overall oxygen content (x) in the SiOx representation is confirmed, the composite nanoparticles with amorphous Si core are formed by the modulation due to the disproportionation reaction at lower temperatures. As a result, the coulombic efficiency is improved, and the higher cycle capacities are attained for the battery using the modulated nanoparticles as an anode.

Dandelion-like Mesoporous SiOx@C Nanoparticles for High-Capacity and Ultralong Lifespan Lithium-Ion Battery Anode

Silicon suboxide (SiOx, 0˂x˂2) is one of the promising anode materials for lithium-ion batteries (LIBs) due to its high specific capacity, low operating voltage (˂0.4 V) and rich natural resource [1]. SiOx converts to Si nanoparticles and inert components (lithium oxide and lithium silicate) during initial lithiation process, where the Si nanoparticles can reversibly store lithium ions and the inert components act as buffer matrix to accommodate the large volume variation of nano-sized Si. Compared to pure Si, SiOx electrode shows relatively good cycling stability while maintaining high specific capacity, thus is a promising anode material for high energy density Li-ion batteries. Nevertheless, bulk SiOx electrode cannot withstand long-term cycling due to the inevitable volume variation upon lithium uptake and removal. In addition, the poor intrinsic electrical conductivity of SiOx often limits the capacity utilization [2]. In this work, we prepared mesoporous SiOx@C nanoparticles with unique “dandelion flower” structure by a facile microemulsion method combined with a subsequent carbon coating process. The SiOx particles display a dandelion flower like porous structure with large void space and specific surface area. A uniform carbon layer wholly encapsulates the SiOx backbone, forming a 3D mono-dispersed SiOx@C particle with particle size of ~70 nm. The abundant mesopores inside particle can accommodate the volume expansion of SiOx during lithiation and lower the diffusion-induced stresses, which prevent from the electrode pulverization and thus maintain the structural integrity of SiOx@C electrode during repeated cycles. The 3D carbon network not only effectively facilitates the fast electron transport throughout the whole SiOx particle and thereby improving the electrode reaction kinetics, but also homogenizes the local current density of active particles and hence decreases the mechanical stress induced by volume change of SiOx. Benefiting from these advantages, the prepared SiOx@C anode exhibits ultrahigh reversible capacity (1261 mAh g-1 at 0.1 A g-1), ultralong lifespan (635 mAh g-1 at 2 A g-1 after 1000 cycles with retention of 88.6%), as well as superior rate capability (293 mAh g-1 at 10 A g-1). [1] Journal of Power Sources, 2017, 363: 126-144. [2] J. Mater. Chem. A, 2014, 2, 3521-3527.

Preparation of Flexible Self‐Supporting 3D SiOx‐Based Membrane Anodes with Stabilized Electrochemical Performances for Lithium‐Ion Batteries

Three‐dimensional (3D) SiOx‐based membrane anodes with stabilized electrochemical performances for lithium‐ion batteries are fabricated ingeniously using high‐capacity SiOx active material. The flexible self‐supporting substances of poly(vinylidene fluoride) and carbon nanotubes are chosen as the supporting substances, which not only provide the 3D framework for the flexible self‐supporting membrane but also act as a protective layer with enhanced conductive pathway. In particular, this unique 3D structure can prevent the SiOx surface from contacting the electrolyte directly and can buffer the volumetric expansion of SiOx particles. This optimized membrane anode exhibits a high reversible specific capacity of 1436 mAh g−1 and a capacity retention rate of 88% after 100 cycles. In addition, it also demonstrates an outstanding rate performance, a specific capacity of 1245 mAh g−1 is obtained at 1200 mA g−1, which is about 91% at 100 mA g−1. The stabilized performances of the as‐prepared membrane anodes indicate their promising prospects in the practical applications, and the fabricating method also provides a reference for the preparation of other flexible self‐supporting membrane electrodes.

Construction of 3D carbon networks with well-dispersed SiO x nanodomains from gelable building blocks for lithium-ion batteries.

Nonstoichiometric silicon oxide (SiOx) with high theoretical capacity is a promising anode material for lithium-ion batteries (LIBs). However, volume changes and poor electronic conductivity of SiOx are major impediments to its practical application. The modification of SiOx with carbonaceous materials to accommodate volume variations and improve conductivity is a valuable strategy. Nanonetwork-structured (NNS) carbons have been paid great attention because of their unique three-dimensional structure, and high electronic and ionic conductivity. Incorporating SiOx with well-designed NNS carbons is a promising method to prepare high quality electrode materials for lithium-ion batteries. In this work, a fabrication approach is developed to synthesize a 3D carbon network composed of carbonaceous hybrid nanotubes with well-dispersed SiOx nanodomains (CNT@SiOx–C) from 1D gelable bottlebrushes as network building blocks based on molecular-scale interface engineering technology. Herein, nano-sized SiOx particles are embedded into the carbonaceous matrix to prevent their volume change during cycling. The experimental results indicated that the CNT@SiOx–C presents high reversible capacity, remarkable cycle life and high rate capability due to the high dispersion of nano-sized SiOx and conductive 3D carbon nanonetwork.

Pseudocapacitance behavior on Fe3O4-pillared SiOx microsphere wrapped by graphene as high performance anodes for lithium-ion batteries

A facile, scalable route is adopted to synthesize egg-like few-layered graphene-wrapped and Fe3O4-pillared SiOx anodes (SiOx@Fe3O4@FLG) for lithium-ion batteries. The rationally designed egg-like SiOx-cored composites possess a strong capability in accommodating volume change of micro-sized SiOx particles during Li cycling. Comprehensive effect of integrated structure, pseudocapacitance contribution and enhanced kinetics enables SiOx@Fe3O4@FLG electrode to afford a high-rate, long-term performance, e.g., 833.4 mA h g−1 (1550 mA h cm−3) at 0.5 A g−1 after 500 cycles with 81.8% capacity retention ratio. Such an attribute makes SiOx@Fe3O4@FLG composites promising anode materials for high-energy Li-ion battery.