lithium doping of polycrystalline silicon

Miller, G. L.; Orr, W. A.

doi:10.1063/1.91887

Cited by 14 publications

(3 citation statements)

References 6 publications

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“…It can also be referred to an improvement of the reaction kinetics during cycling by repeatedly insertion/extraction of lithium ions in which the conductivity may improve as a result of the lithium-doping or changes in geometry. 50 Galvanostatic charge/discharge experiments of the Al/SiNWs electrode with different Al weight percentages were carried out in the voltage range of 0.01-2 V. Uncoated SiNWs/TiN electrode was also measured for comparison. Fig.…”

Section: Resultsmentioning

confidence: 99%

Silicon nanowire core aluminum shell coaxial nanocomposites for lithium ion battery anodes grown with and without a TiN interlayer

et al. 2012

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We investigated the effect of aluminum coating layers and of the support growth substrates on the electrochemical performance of silicon nanowires (SiNWs) used as negative electrodes in lithium ion battery half-cells. Extensive TEM and SEM analysis was utilized to detail the cycling induced morphology changes in both the Al-SiNW nanocomposites and in the baseline SiNWs. We observed an improved cycling performance in the Si nanowires that were coated with 3 and 8 wt.% aluminum. After 50 cycles, both the bare and the 3 wt.% Al coated nanowires retained 2600 mAh/g capacity. However beyond 50 cycles, the coated nanowires showed higher capacity as well as better capacity retention with respect to the first cycle. Our hypothesis is that the nanoscale yet continuous electrochemically active aluminum shell places the Si nanowires in compression, reducing the magnitude of their cracking/ disintegration and the subsequent loss of electrical contact with the electrode. We combined impedance spectroscopy with microscopy analysis to demonstrate how the Al coating affects the solid electrolyte interface (SEI). A similar thickness alumina (Al 2 O 3 ) coating, grown via atomic layer deposition (ALD), was shown not to be as effective in reducing the long-term capacity loss. We demonstrate that an electrically conducting TiN barrier layer present between the nanowires and the underlying stainless steel current collector leads to a higher specific capacity during cycling and a significantly improved coulombic efficiency. Using TiN the irreversible capacity loss was only 6.9% from the initial 3581 mAh/g, while the first discharge (lithiation) capacity loss was only 4%. This is one of the best combinations reported in literature.

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Section: Resultsmentioning

confidence: 99%

Silicon nanowire core aluminum shell coaxial nanocomposites for lithium ion battery anodes grown with and without a TiN interlayer

et al. 2012

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“…These atoms move along the ͗111͘ channels in a zigzag fashion, alternatively passing through the tetrahedral and hexagonal interstitial sites of the lattice, which are their equilibrium and saddle points for diffusion. [23][24][25] On the other hand, a high diffusivity of a possible codopant is not desirable in the manufacturing process of shallow junctions. However, experiments have shown that the presence of 10 18 cm −3 carbon reduces the room temperature diffusion rate of Li to 0.1% of its value in pure Si.…”

Section: B Trapping Of Codopants At Dopant Clustersmentioning

confidence: 99%

Codoping as a measure against donor deactivation in Si:Ab initiocalculations

Mueller¹,

Fichtner²

2006

Phys. Rev. B

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Based on ab initio calculations, we evaluate the effectiveness of various group I, II, and IV elements as possible codopants in highly n-doped Si. The fabrication of ultrashallow junctions in future silicon technology requires the suppression of donor deactivation and diffusion during the annealing. The main goal is therefore the elimination of excess vacancies, both isolated and in donor-vacancy ͑D n V m ͒ clusters. We find that the isovalent impurities C and Ge are unsuited for the intended purpose of D n V m clustering inhibition. Alkali and earth alkaline metals, on the other hand, can partially reactivate the donors present in clusters at heavy n-type doping. Moreover, by annihilating the vacancies, they inhibit in part the vacancy-mediated donor diffusion. Magnesium and beryllium exhibit very promising properties for the codoping strategy proposed in this paper.

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“…In large amounts, Li-doping can counter-dope an initially doped p-type silicon and make it n-type. 23 Amorphous silicon doped by lithium diffusion results in n-type, because Li are placed on silicon interstitials donating one electron. 24 A silicon structure with one Li atom in an interstitial has a similar electronic structure as one with a Si atom replaced with arsenic in the sense that both, arsenic and lithium, yield one free-electron resulting in n-type doping.…”

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confidence: 99%

Simulations of a LiF Solid Electrolyte Interphase Cracking on Silicon Anodes Using Molecular Dynamics

Galvez-Aranda

Seminario

2018

J. Electrochem. Soc.

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The main advantage of silicon-based anodes for lithium-ion batteries is their high volumetric and gravimetric capacity to store Li. However, swelling upon lithiation causes cracks on the anode protective solid electrolyte interphase (SEI), creating channels for the electrolyte to enter and disturb the anode, leading to capacity fading, short-or open-circuit failures. We study the mechanical properties of LiF as a model SEI layer of a SiLi nanoparticle (NP) swollen by a time-dependent expanding potential (TDEP) simulating the lithiation of Si. The stress on the SEI increases until reaching its maximum at LiF bond breaking and cracking onsets. Then, stress decreases and the number of bonds in the SEI approaches a minimum, confirming the cracking. However, at the lowest currents, atoms have enough relaxation time that a surface reconstruction is observed and the stress reaches a second and higher maximum, then the SEI layer breaks into pieces. The microscopic amorphization mechanism is found to be independent of the charging rate; however, the value of the tensile strength depends on the expanding rate. LiF bonds breaking begins with those nearest to the SiLi-LiF interface, along a radial direction, then forming larger LiF rings until the SiLi alloy loses its protective shell

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lithium doping of polycrystalline silicon

Abstract: Electrolytic lithium doping of high-purity polycrystalline silicon samples has been shown to increase not only the material conductivity but also the minority-carrier lifetime.

Cited by 14 publications

References 6 publications

Silicon nanowire core aluminum shell coaxial nanocomposites for lithium ion battery anodes grown with and without a TiN interlayer

Silicon nanowire core aluminum shell coaxial nanocomposites for lithium ion battery anodes grown with and without a TiN interlayer

Codoping as a measure against donor deactivation in Si:Ab initiocalculations

Simulations of a LiF Solid Electrolyte Interphase Cracking on Silicon Anodes Using Molecular Dynamics

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