Article

High-Performance Lithium Battery Anodes Using Silicon Nanowires

Nature Nanotechnology (Impact Factor: 34.05). 01/2008; 3(1):31-5. DOI: 10.1038/nnano.2007.411
Source: PubMed

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.

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Available from: Robert A Huggins
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    • "Many studies in the past have therefore focused on increasing the charge and energy storage capacity of lithium-ion battery electrodes, Kasavajjula et al. (2007). It is well known that silicon offers the highest known theoretical charge capacity, nearly ten times that of the conventional graphite electrodes, Chan et al. (2008).However, high-capacity electrodes often suffer from a variety of mechanical degradation modes, such as fracture and loss of electric contact with current collector or other active/inactive phases in the electrode.Such failures are often driven by large intercalation-induced stresses which emerge as a result of volume changes associated with ionic insertion/extraction during lithium cycling. It is therefore of great interest to design electrodes capable of accommodating large volume expansions/contractions without loss of mechanical integrity.To this end, many studies have focused on various nano-engineered electrodes, such as nanocomposites, nanowires, nanoparticles and nano-scale thin films, Graetz et al. (2004), Liu et al. (2011), Liu et al. (2012), Maranchi et al. (2006). "
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    ABSTRACT: High-capacity anodes such as Si are gaining critical importance for energy-storage purposes in a variety of industries. However, they are well known to suffer from capacity fading which is induced by loss of mechanical integrity during cycling. Among various nano-structured electrodes, nano-scale thin films deposited on thick substrates have been widely studied through experimental and theoretical methods. Experiments show that even nano-scale thin-film electrodes could undergo extensive fracture and delamination from the underneath current collector. In this paper, we examine the effect of interaction between chemical and mechanical driving forces on the solute distribution in the vicinity of the edge of an elastic semi-infinite nano-film which is bonded onto the surface of a thick elastic substrate. The film as opposed to the substrate is considered chemically active, and in chemical equilibrium with an external infinitely large mass reservoir which maintains a uniform chemical potential everywhere in the film. Mechanical deformation of the film is studied using the membrane approximation theory, and the thick substrate is modelled as an elastic half space. It is shown that solute distribution is highly non-uniform close to the film edge. The effect of solute segregation on the axial stress distribution in the film is also examined.
    Full-text · Article · Dec 2015
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    • "Decreasing the particle size up to the nanoscale and compositing with conducting carbon to form specific architecture has been proved to be an effective approach for high-stability Si anode. Various structural and dimensional nano-sized Si have been successfully synthesized by different approach, including Si nanowire via VLS process [14], Si nanofiber by chemical vapor deposition [15] [16] [17], nest-like Si via solvothermal route [18], Si nanotube synthesized via supercritical fluid-liquid–solid (SFLS) [14] [19] [20], porous Si fabricated by etching from bulk silicon or inducing porous template. Using electrochemical etching [21] [22] [23] or acid etching [24] [25] [26] [27] [28] can convert bulk silicon into porous silicon with tunable pore size and it can also be obtained by filling up the void place and then etching away template [29] [30] [31]. "
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    ABSTRACT: Developing scalable, simple and low-cost synthesis approach for Si nanoparticles and fabricating Si/carbon composites with specific microstructure to improve the Li storage ability are of great significance for practical application of Si-based Li-ion battery anode. In this report, we employed a facile method to synthesize Si nanoparticles via acid-etching Al-Si alloy powder. The etching process was fully investigated. The as-synthesized Si nanoparticles (∼10 nm) were further embedded into graphene sheets to form a flexible, free-standing paper with "sandwich-like" structure. The Si/graphene paper was directly applied as anode for Li-ion batteries without adding any binder and conductive additive. The graphene sheets not only increase the conductivity of Si material, but also function as a flexible scaffold for strains/stresses release and volume expansion during charge/discharge cycling process, resulting in much higher cycling stability (1500 mAh g-1 after 100 cycles at a current density of 100 mA g-1 with Coulombic efficiency >99%) compared to the native Si nanoparticles. It provides a scalable Si nanoparticles synthesis approach and a promising high-performance Si/graphene anode material.
    Full-text · Article · Dec 2015
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    • "However, Si is subjected to extremely large volume change ($400%) during lithiation/delithiation process, which causes the pulverization of Si particles and loss of the electrical connection with current collector, resulting in rapid capacity fading. In addition, the severe volume change also brings about the repeated formation of solid electrolyte interphase (SEI) layer on Si surface, leading to low Coulombic efficiency (CE) during cycling process [4] [5] [6]. Moreover, the low intrinsic electrical conductivity of Si further compromises its cyclic stability and rate performance [7] [8]. "
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    ABSTRACT: Graphene and other carbon materials have been combined with various silicon (Si) nanostructures to accommodate the volume change of Si and enhance their electrical conductivity. However, for most of the formed hybrids, their low initial Coulombic efficiency (CE), fragile structures and poor stability cannot meet the practical application of battery. In this work, inspired by the structure and composition of reinforced concrete, a Si nanoparticles embedded in porous carbon/graphene (Si-C/G) electrode is fabricated through directly calcining a Si-polyacrylonitrile/graphene oxide precursor on a current collector. In this concrete-like structure, amorphous carbon, the carbonization product of polyacrylonitrile, acts as the “cement” and binds all components together. The flexible graphene network effectively enhances the strength, flexibility and conductivity of the electrode, as does the reinforcing rod framework in concrete. This carbon/graphene scaffold can accommodate the volume expansion of Si and isolate Si from electrolyte. Such Si-C/G electrode with small surface area and compact structure achieves a high initial CE of 78% and a reversible capacity of 1711 mAh g−1, as well as outstanding rate and cycling performances.
    Full-text · Article · Nov 2015 · Carbon
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