Silicon prepared by electro-reduction in molten salts as new energy materials

Jiang, Tingting; Xu, Xinyi

doi:10.1016/j.jechem.2019.11.005

Cited by 35 publications

(21 citation statements)

References 61 publications

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“…The free space between the nanowires can accommodate volume expansion, minimize internal stress, and keep the structural integrity of the electrode, resulting in high and stable Coulombic efficiency [8,48]. Moreover, the small diameter of the nanowires is able to mitigate the large volume change of the silicon, resulting in better cycling performance of the LIBs [49]. After 100 cycles, the cycling stability of the half-cell using an n-SiNW electrode was better than previous reports on Si NW anodes prepared by chemical vapor deposition (CVD) and metal-assisted chemical etching (MACE) that reported capacity retention of up to only 83% [19,50,51].…”

Section: Resultsmentioning

confidence: 99%

Vertically Aligned n-Type Silicon Nanowire Array as a Free-Standing Anode for Lithium-Ion Batteries

et al. 2021

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Due to its high theoretical specific capacity, a silicon anode is one of the candidates for realizing high energy density lithium-ion batteries (LIBs). However, problems related to bulk silicon (e.g., low intrinsic conductivity and massive volume expansion) limit the performance of silicon anodes. In this work, to improve the performance of silicon anodes, a vertically aligned n-type silicon nanowire array (n-SiNW) was fabricated using a well-controlled, top-down nano-machining technique by combining photolithography and inductively coupled plasma reactive ion etching (ICP-RIE) at a cryogenic temperature. The array of nanowires ~1 µm in diameter and with the aspect ratio of ~10 was successfully prepared from commercial n-type silicon wafer. The half-cell LIB with free-standing n-SiNW electrode exhibited an initial Coulombic efficiency of 91.1%, which was higher than the battery with a blank n-silicon wafer electrode (i.e., 67.5%). Upon 100 cycles of stability testing at 0.06 mA cm−2, the battery with the n-SiNW electrode retained 85.9% of its 0.50 mAh cm−2 capacity after the pre-lithiation step, whereas its counterpart, the blank n-silicon wafer electrode, only maintained 61.4% of 0.21 mAh cm−2 capacity. Furthermore, 76.7% capacity retention can be obtained at a current density of 0.2 mA cm−2, showing the potential of n-SiNW anodes for high current density applications. This work presents an alternative method for facile, high precision, and high throughput patterning on a wafer-scale to obtain a high aspect ratio n-SiNW, and its application in LIBs.

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Section: Resultsmentioning

confidence: 99%

Vertically Aligned n-Type Silicon Nanowire Array as a Free-Standing Anode for Lithium-Ion Batteries

et al. 2021

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“…Another route is the electrochemical reduction of Si in molten salt, which could realize relatively high purity Si products with morphology-controllable nanostructures at lower temperatures (generally 650-900 • C) in comparison with the carbothermic reduction method (Jiang et al, 2020). The production yield and efficiency are the biggest problems which limit its commercial application.…”

Section: Preparation Methods Of Silicon-based Negative Electrode Matementioning

confidence: 99%

Mechanisms and Product Options of Magnesiothermic Reduction of Silica to Silicon for Lithium-Ion Battery Applications

Tan

Jiang

2021

Front. Energy Res.

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Lithium-ion batteries (LIBs) have been one of the most predominant rechargeable power sources due to their high energy/power density and long cycle life. As one of the most promising candidates for the new generation negative electrode materials in LIBs, silicon has the advantages of high specific capacity, a lithiation potential range close to that of lithium deposition, and rich abundance in the earth’s crust. However, the commercial use of silicon in LIBs is still limited by the short cycle life and poor rate performance due to the severe volume change during Li++ insertion/extraction, as well as the unsatisfactory conduction of electron and Li+ through silicon matrix. Therefore, many efforts have been made to control and stabilize the structures of silicon. Magnesiothermic reduction has been extensively demonstrated as a promising process for making porous silicon with micro- or nanosized structures for better electrochemical performance in LIBs. This article provides a brief but critical overview of magnesiothermic reduction under various conditions in several aspects, including the thermodynamics and mechanism of the reaction, the influences of the precursor and reaction conditions on the dynamics of the reduction, and the interface control and its effect on the morphology as well as the final performance of the silicon. These outcomes will bring about a clearer vision and better understanding on the production of silicon by magnesiothermic reduction for LIBs application.

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“…The abundant presence of Si can be the result of (1) the presence of type-B sparks creating preferential channels for Si ingress, or (2) the presence of high electric fields, as the result of the considerably thinner coating, enhancing electrophoretic motion of ions. Moreover, the high temperature involved during plasma formation and the presence of a cathodic half-cycle can favor faster kinetics of cathodic reactions, leading to Si formation, such as [43] SiO 2 + 4e − → Si +2O 2− (8…”

Section: Discussionmentioning

confidence: 99%

Addition of Organic Acids during PEO of Titanium in Alkaline Solution

et al. 2022

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This research study describes recent advances in understanding the effects of the addition of organic acids, such as acetic, lactic, citric and phytic acids, on the process of plasma electrolytic oxidation (PEO) on Ti using an alkaline bath. As the plasma developed over the workpiece is central to determine the particular morphological and structural features of the growing oxide, the focus is then on the inter-relationships between the electrolyte and the resultant plasma regime established. In situ optical emission spectroscopy (OES) allowed us to verify a marked plasma suppression when adding low-molecular-weight anions such as acetates, resulting in short-lived and well-distributed discharges. Conversely, when more bulky anions, such as lactates, citrates and phytates, were considered, a less efficient shielding of the electrode caused the build-up of long-lasting and destructive sparks responsible for the formation of thicker coatings, even >30 µm, at the expense of a higher roughness and loss of compactness. Corrosion resistance was tested electrochemically, according to electrochemical impedance spectroscopy (EIS), and weight losses evidenced the coatings produced in the solution containing acetates to be more suitable for service in H2SO4.

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Silicon prepared by electro-reduction in molten salts as new energy materials

Cited by 35 publications

References 61 publications

Vertically Aligned n-Type Silicon Nanowire Array as a Free-Standing Anode for Lithium-Ion Batteries

Vertically Aligned n-Type Silicon Nanowire Array as a Free-Standing Anode for Lithium-Ion Batteries

Mechanisms and Product Options of Magnesiothermic Reduction of Silica to Silicon for Lithium-Ion Battery Applications

Addition of Organic Acids during PEO of Titanium in Alkaline Solution

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