Structural changes in silicon anodes during lithium insertion/extraction
TL;DR: In this article, the structural changes in silicon electrochemically lithiated and delithiated at room temperature were studied by X-ray powder diffraction, and it was shown that highly lithiated amorphous silicon suddenly crystallizes at 50 mV to form a new lithium-silicon phase, identified as This phase is the fully lithiated phase for silicon at room-temperature, not as is widely believed.
Abstract: The structural changes in silicon electrochemically lithiated and delithiated at room temperature were studied by X-ray powder diffraction. Crystalline silicon becomes amorphous during lithium insertion, confirming previous studies. Highly lithiated amorphous silicon suddenly crystallizes at 50 mV to form a new lithium-silicon phase, identified as This phase is the fully lithiated phase for silicon at room temperature, not as is widely believed. Delithiation of the phase results in the formation of amorphous silicon. Cycling silicon anodes above 50 mV avoids the formation of crystallized phases completely and results in better cycling performance. © 2004 The Electrochemical Society. All rights reserved.
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TL;DR: The battery systems reviewed here include sodium-sulfur batteries that are commercially available for grid applications, redox-flow batteries that offer low cost, and lithium-ion batteries whose development for commercial electronics and electric vehicles is being applied to grid storage.
Abstract: The increasing interest in energy storage for the grid can be attributed to multiple factors, including the capital costs of managing peak demands, the investments needed for grid reliability, and the integration of renewable energy sources. Although existing energy storage is dominated by pumped hydroelectric, there is the recognition that battery systems can offer a number of high-value opportunities, provided that lower costs can be obtained. The battery systems reviewed here include sodium-sulfur batteries that are commercially available for grid applications, redox-flow batteries that offer low cost, and lithium-ion batteries whose development for commercial electronics and electric vehicles is being applied to grid storage.
11,144 citations
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TL;DR: In this paper, a review of methodologies adopted for reducing the capacity fade observed in silicon-based anodes, discuss the challenges that remain in using silicon and siliconbased anode, and propose possible approaches for overcoming them.
2,372 citations
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
Cites background from "Structural changes in silicon anode..."
...Such a design has multiple advantages: (1) the nanosized primary particle size prevents fracture; (2) the well-defined internal void space allows the silicon to expand without changing the secondary particle size; (3) the carbon framework functions as an electrical highway and a mechanical backbone so that all nanoparticles are electrochemically active; (4) carbon completely encapsulates the entire secondary particle, limiting most SEI formation to the outer surface instead of on individual nanoparticles, which not only limits the amount of SEI, but also retains the internal void space for silicon expansion; and (5) the dilemma of high surface area and low tap density introduced when using nanosized primary features is partially solved....
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TL;DR: In this paper, the authors highlight the recent progress in improving and understanding the electrochemical performance of various alloy anodes, and the causes of first-cycle irreversible capacity loss are discussed.
1,857 citations
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TL;DR: In this paper, the authors show that the mechanism of electrochemical alloying is electrochemically-driven solid state amorphization, a process closely analogous to the diffusive solid-state amomorphization of thin films.
486 citations
TL;DR: In this paper, the crystal structure and morphology of nanosized Si particles and wires after Li-insertion/extraction electrochemically have been studied by ex-situ XRD, Raman spectroscopy and electronic microscopy.
446 citations
TL;DR: The properties of amorphous 250 nm and 1 μm silicon films deposited by radiofrequency (RF) magnetron sputtering on copper foil are investigated using X-ray diffraction, scanning electron microscopy (SEM), and electrochemical methods as mentioned in this paper.
Abstract: The properties of amorphous 250 nm and 1 μm silicon films deposited by radio-frequency (rf) magnetron sputtering on copper foil are investigated using X-ray diffractιon, scanning electron microscopy (SEM), and electrochemical methods. Galvanostatic half-cell electrochemical measurements conducted between 0.02 and 1.2 V using a lithium counter electrode have shown that the 250 nm Si thin films exhibit an excellent reversible specific capacity of nearly 3500 mAh/g when tested for 30 cycles. The high reversible capacity and excellent cyclability of the 250 nm sputtered silicon thin films suggest excellent adhesion between Si and Cu leading to high capacity retention. SEM analysis conducted on the 250 nm Si films after the 30th charge suggests the good adhesion of the ∼2 μm diam "plates" of silicon to the copper substrate.
441 citations
01 May 1981
TL;DR: The equilibrium coulometric titration curve shows four intermediate phases in the Li-Si system at 415/sup 0/C as discussed by the authors, and the nominal compositions for these phases are Li/sub 12/Si/sub 7, Li-sub 7/Si-sub 3, Li/Sub 13/Si+sub 4, and Li/ Sub 22/Si−sub 5, respectively.
Abstract: The equilibrium coulometric titration curve shows four intermediate phases in the Li-Si system at 415/sup 0/C. The nominal compositions for these phases are Li/sub 12/Si/sub 7/, Li/sub 7/Si/sub 3/, Li/sub 13/Si/sub 4/, and Li/sub 22/Si/sub 5/, respectively. They all have quite narrow ranges of homogeneity. The compositional variations of the chemical diffusion coefficients within the various intermediate phases are similar to each other and closely resemble those of the thermodynamic enhancement factor for each phase. The chemical diffusion coefficients across all four intermediate phase are essentially of the same order, about 6.0 x 10/sup -5/ cm/sup 2//s at 415/sup 0/C. 9 figures.
429 citations
TL;DR: In this paper, binary lithium-silicon and ternary lithium-chromium-silicons were produced and then characterized by X-ray diffraction, as well as electrochemical methods at room temperature.
313 citations