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Journal ArticleDOI

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

18 Sep 2017-ACS Applied Materials & Interfaces (American Chemical Society)-Vol. 9, Iss: 38, pp 32790-32800
TL;DR: An outstanding electrochemical performance of Si@SiC-0.5 is attributed to the SiC phase, which acts as a buffer layer that stabilizes the nanostructure of the Si active phase and enhances the electrical conductivity of the electrode.
Abstract: Here, we propose a simple method for direct synthesis of a Si@SiC composite derived from a SiO2@C precursor via a Mg thermal reduction method as an anode material for Li-ion batteries. Owing to the extremely high exothermic reaction between SiO2 and Mg, along with the presence of carbon, SiC can be spontaneously produced with the formation of Si. The synthesized Si@SiC was composed of well-mixed SiC and Si nanocrystallites. The SiC content of the Si@SiC was adjusted by tuning the carbon content of the precursor. Among the resultant Si@SiC materials, the Si@SiC-0.5 sample, which was produced from a precursor containing 4.37 wt % of carbon, exhibits excellent electrochemical characteristics, such as a high first discharge capacity of 1642 mAh g–1 and 53.9% capacity retention following 200 cycles at a rate of 0.1C. Even at a high rate of 10C, a high reversible capacity of 454 mAh g–1 was obtained. Surprisingly, at a fixed discharge rate of C/20, the Si@SiC-0.5 electrode delivered a high capacity of 989 mAh g...
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Journal ArticleDOI
TL;DR: 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.
Abstract: 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.

95 citations

Journal ArticleDOI
TL;DR: In this paper, a 3D hierarchical macro-mesoporous SiO2/C composite is proposed to improve the cyclic performance of the Si anodes by using a self-templating mechanism during the reduction process.

69 citations

Journal ArticleDOI
TL;DR: 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 theSCMSC structure.

56 citations

Journal ArticleDOI
TL;DR: In this paper, a mass-produced and low-cost hierarchical mesoporous/macroporous silicon-based composite material with an ample porous structure and dual carbon protective layers has been rationally designed and constructed.
Abstract: Despite the fact that the silicon-based anode has attracted immense attention with extremely high theoretical capacity, practical applications have been impeded by severe capacity fading during cycling processes and high preparation cost. In this work, a mass-produced and low-cost hierarchical mesoporous/macroporous silicon-based composite material with an ample porous structure and dual carbon protective layers has been rationally designed and constructed. Through adjusting the phase ratio of intermediate products (Mg2Si and MgO), the traditional magnesiothermic reduction method based on the low cost silicon source of diatomaceous earth (DE) has been precisely optimized to fabricate a controlled mesoporous structure on the original macroporous structure of DE. Furthermore, dual carbon protective layers on the hierarchical mesoporous/macroporous structure silicon-based composite material have also been constructed using the vacuum adsorption technique, showing that both the porous channel and the composite material surface are wrapped with carbon. Electrochemical performance tests show that both the controlled mesoporous/macroporous structure and dual carbon protective layers have enhanced the cycle stability of the Si/SiO2@C composite anode material for lithium-ion batteries. The capacity retention of the hierarchical mesoporous/macroporous Si/SiO2@C composite material with 13% carbon can reach 99.5% after 200 electrochemical cycles, and the reversible capacity can reach 534.3 mA h g−1 even at 500 mA g−1. This paper not only provides a low-cost and high electrochemical property silicon-based composite anode material for lithium-ion batteries, which possesses important significance in both academic and industrial worlds, but also opens up a way on how to design the hierarchical mesoporous/macroporous structure with precision control on the phase ratio.

52 citations

Proceedings ArticleDOI
06 Oct 1986
TL;DR: In this article, the concept of inertial fiber motion sensors based upon the Kennedy-Thorndike interferometer is introduced, which can enable inertial strapdown navigation without accelerometers.
Abstract: The fiber gyro, utilizing the Sagnac effect and under development since the early 1980s, has reached production status as a low-cost rotation rate sensor for various high volume applications, satisfied by drift rates of 10°/h and more. Lower drift rates will be offered by series production fiber gyros within the next two years. Principles, technologies and performance data of SEL fiber gyros are discussed, as well as some principal applications. The paper introduces also the concept of a new class of inertial fiber motion sensors based upon the Kennedy-Thorndike interferometer. Such sensors for inertial velocity can enable inertial strapdown navigation without accelerometers.

50 citations

References
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Journal ArticleDOI
06 Feb 2008-Nature
TL;DR: Researchers must find a sustainable way of providing the power their modern lifestyles demand to ensure the continued existence of clean energy sources.
Abstract: Researchers must find a sustainable way of providing the power our modern lifestyles demand.

15,980 citations

Journal ArticleDOI
TL;DR: The theoretical charge capacity for silicon nanowire battery electrodes is achieved and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.
Abstract: There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.

6,104 citations

Journal ArticleDOI
TL;DR: This review offers details of the technologies, in terms of needs, status, challenges and future R&d directions, that are expected to integrate significant levels of renewables into the electrical grid.
Abstract: The is a comprehensive review on the needs and potential storage technologies for electrical grid that is expected to integrate significant levels of renewables. This review offers details of the technologies, in terms of needs, status, challenges and future R&d directions.

4,096 citations

Journal ArticleDOI
TL;DR: The design is inspired by the structure of a pomegranate, where single silicon nanoparticles are encapsulated by a conductive carbon layer that leaves enough room for expansion and contraction following lithiation and delithiation, resulting in superior cyclability and Coulombic efficiency.
Abstract: Silicon is an attractive material for anodes in energy storage devices1,2,3, because it has ten times the theoretical capacity of its state-of-the-art carbonaceous counterpart. Silicon anodes can be used both in traditional lithium-ion batteries and in more recent Li–O2 and Li–S batteries as a replacement for the dendrite-forming lithium metal anodes. The main challenges associated with silicon anodes are structural degradation and instability of the solid-electrolyte interphase caused by the large volume change (∼300%) during cycling, the occurrence of side reactions with the electrolyte, and the low volumetric capacity when the material size is reduced to a nanometre scale4,5,6,7. Here, we propose a hierarchical structured silicon anode that tackles all three of these problems. Our design is inspired by the structure of a pomegranate, where single silicon nanoparticles are encapsulated by a conductive carbon layer that leaves enough room for expansion and contraction following lithiation and delithiation. An ensemble of these hybrid nanoparticles is then encapsulated by a thicker carbon layer in micrometre-size pouches to act as an electrolyte barrier. As a result of this hierarchical arrangement, the solid-electrolyte interphase remains stable and spatially confined, resulting in superior cyclability (97% capacity retention after 1,000 cycles). In addition, the microstructures lower the electrode–electrolyte contact area, resulting in high Coulombic efficiency (99.87%) and volumetric capacity (1,270 mAh cm−3), and the cycling remains stable even when the areal capacity is increased to the level of commercial lithium-ion batteries (3.7 mAh cm−2). A Si anode with hierarchical morphology can accommodate large volume changes, demonstrates high Coulombic efficiency and cyclability as well as an areal capacity comparable to that of commercial Li-ion batteries.

2,094 citations

Journal ArticleDOI
TL;DR: A large-scale hierarchical bottom-up assembly route for the formation of Si on the nanoscale--containing rigid and robust spheres with irregular channels for rapid access of Li ions into the particle bulk.
Abstract: Si-based Li-ion battery anodes have recently received great attention, as they offer specific capacity an order of magnitude beyond that of conventional graphite. The applications of this transformative technology require synthesis routes capable of producing safe and easy-to-handle anode particles with low volume changes and stable performance during battery operation. Herein, we report a large-scale hierarchical bottom-up assembly route for the formation of Si on the nanoscale--containing rigid and robust spheres with irregular channels for rapid access of Li ions into the particle bulk. Large Si volume changes on Li insertion and extraction are accommodated by the particle's internal porosity. Reversible capacities over five times higher than that of the state-of-the-art anodes (1,950 mA h g(-1)) and stable performance are attained. The synthesis process is simple, low-cost, safe and broadly applicable, providing new avenues for the rational engineering of electrode materials with enhanced conductivity and power.

1,873 citations