Effect of Heat Treatment on Si Electrodes Using Polyvinylidene Fluoride Binder

Li, Jing; Christensen, Leif Højslet; Obrovac, M. N.; Hewitt, K. C.; Dahn, J. R.

doi:10.1149/1.2830545

Cited by 118 publications

(113 citation statements)

References 33 publications

(46 reference statements)

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“…The weight loss from 392 to 439°C can be attributed to random chain scission of the cross-linked GMA on the end of m-PEI [36]. The onset pyrolysis temperature of PVDF is as high as 400°C [37], and when it was blended with m-PEI and electrospun into m-PEI/PVDF nanofibrous mats, its thermal stability clearly declined. The decomposition of PVDF would start at about 280°C.…”

Section: Resultsmentioning

confidence: 99%

Polyethylenimine nanofibrous adsorbent for highly effective removal of anionic dyes from aqueous solution

Zhang

et al. 2016

Sci. China Mater.

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(Li J)) most common byproducts of the paint manufacture, dyeing, cosmetics, textile, paper, leather, and other industries, and it can poison the environment and endanger the safety of drinking water and foodstuffs [5,6]. Therefore, removal of organic dye from water is a major project for the development of a sustainable society [7].Adsorption is recognized as one of the most promising methods because of its high effectiveness, low cost, and popularity [8,9]. Polymeric adsorbents are widely used as materials for the removal of organic or inorganic contaminants from water or air because of their advantages such as high flexibility in the design of structures and properties; chemical stability in harsh environments, including strong acidic, alkaline, salty, and oxidizing solutions; feasible regeneration; and thermal durability [9][10][11]. Polyethylenimine (PEI) has a high amine density and accessible primary amine sites on the chain ends, which act as desirable building blocks for the construction of adsorbents. For instance, many excellent CO 2 adsorbents have been prepared by integrating PEI into porous materials, including silica [12], mesoporous carbon [13], titanate [14], polymeric supports [15], and other metal oxide nanocomposites [16]. In addition, because of the high positive charge density on the protonated PEI backbone or side chains, PEI-based adsorbents exhibit good adsorption capacity for acidic gas or anionic materials such as polyanions and negatively charged organic or inorganic matter, including various anionic dyes [16][17][18][19].Electrospinning is an effective approach to prepare ultrafine fibers; it uses an electrostatic force from an external high-voltage electrical field between a spinneret and a grounded collector to draw very fine (typically micro-to nanoscale) fibers from a liquid droplet [20]. The ultrafine fibers produced by electrospinning have very high specific ABSTRACT We prepared a nanofibrous adsorbent for anionic dye removal from aqueous solution by electrospinning a modified polyethylenimine (m-PEI) and polyvinylidene fluoride (PVDF) blend. The electrospun nanofibrous adsorbent was confirmed to be a nanoscale, porous material with a positively charged surface; these characteristics are quite beneficial for anionic contaminant adsorption. Experimental adsorption of an anionic dye, methyl orange (MO), demonstrates that this adsorbent can rapidly remove MO from aqueous solution; its maximum adsorption capacity was 633.3 mg g −1 , which is much higher than that of previously reported adsorbents. After immersion in a basic solution, the adsorbent was well regenerated and showed good recyclability. The adsorption performance of the nanofibrous adsorbent is greatly influenced by the temperature, initial MO concentration, and pH of the solution. We further found that MO adsorption onto the adsorbent can be described well by the pseudo-second-order kinetic model and Langmuir isotherm model. Weber-Morris plots suggested that the adsorption of MO onto the nanofibrous mat was affected...

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Section: Resultsmentioning

confidence: 99%

Polyethylenimine nanofibrous adsorbent for highly effective removal of anionic dyes from aqueous solution

Zhang

et al. 2016

Sci. China Mater.

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“…It is worth noting that relatively strong supramolecular interactions of urea groups, rather than the mechanical property such as low T g , is the key parameter for the stable cycling performance, which is in good accordance with other reports. 31,55,56 To elaborate this view point, they also synthesized a low T g polymer with the same structure but without urea moieties. The SiMP with this control polymer showed much worse capacity retention, indicating that urea-based hydrogen bonding is essential for the observed cycling performance.…”

Section: Urea-based Bindermentioning

confidence: 99%

The emerging era of supramolecular polymeric binders in silicon anodes

2018

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Silicon (Si) anode is among the most promising candidates for the next-generation high-capacity electrodes in Li-ion batteries owing to its unparalleled theoretical capacity (4200 mA h g À1 for Li 4.4 Si) that is approximately 10 times higher than that of commercialized graphitic anodes (372 mA h g À1 for LiC 6 ).The battery community has witnessed substantial advances in research on new polymeric binders for silicon anodes mainly due to the shortcomings of conventional binders such as polyvinylidene difluoride (PVDF) to address problems caused by the massive volume change of Si (300%) upon (de)lithiation. Unlike conventional battery electrodes, polymeric binders have been shown to play an active role in silicon anodes to alleviate various capacity decay pathways. While the initial focus in binder research was primarily to maintain the electrode morphology, it has been recently shown that polymeric binders can in fact help to stabilize cracked Si microparticles along with the solid-electrolyte-interphase (SEI) layer, thus substantially improving the electrochemical performance. In this review article, we aim to provide an in-depth analysis and molecular-level design principles of polymeric binders for silicon anodes in terms of their chemical structure, superstructure, and supramolecular interactions to achieve good electrochemical performance. We further highlight that supramolecular chemistry offers practical tools to address challenging problems associated with emerging electrode materials in rechargeable batteries.

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“…In an effort to selectively detect the 29 Si NMR resonances of silicon environments that are in close proximity to protons (i.e. the surface silicon atoms) 1 H/ 29 Si cross polarization solid state experiments were also performed on the thin films prepared. The comparison of the single pulse and cross polarization data shows that, peaks within −40 to −70 ppm region for the sample prepared with TEACl are mostly due to amorphous silicon with different particle sizes rather than silicon hydrides (Figure 7).…”

Section: Resultsmentioning

confidence: 99%

Effect of Surface Termination on Electrochemical Performance of Silicon Thin Films

Doğan

Vaughey

2015

J. Electrochem. Soc.

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The surface termination layer of silicon-based lithium-ion anodes is a complex mixture of silicon oxides, hydroxides, and hydrides. The species present reflect the history of the electrode and combine to make each silicon electrode different in its electrochemical performance and reactivity with the electrolyte. This variability creates challenges for silicon-based anodes as it affects SEI formation and stability, columbic efficiency, and irreversible capacity. To elucidate some of the parameters that control surface functionality we used non-aqueous electrodeposition to produce silicon thin films on copper foams. These porous electrodes were studied using 29 Si MAS NMR to correlate the synthetic process and surface functionality with electrochemical performance. We found that the supporting electrolyte salt used has a significant effect on the electrodeposited silicon thin films electrochemical properties. Films deposited using tetrabutylammonium chloride (TBACl) were found to be more crystalline with much higher surface concentration of hydrides, hydroxides and oxides, have lower capacity, and much higher irreversible capacity than films deposited using tetraethylammonium chloride (TEACl). The role of supporting electrolyte salt is hypothesized to be related to the amount of free solvent in the reaction mixture as the TBACl salt has been reported to tie up significantly more solvent due its larger size. For many new LIB applications, the space available for the energy storage component in the end device is at a premium. This need is driving the search for new couples that can be designed, modified, or optimized to meet these volumetric goals. Among the materials under study, silicon is a promising alternative anode material to replace graphitic carbon in Li-ion batteries. Its attributes, including high specific capacity, both gravimetric (>3500 mAh/g) and volumetric (>2194 mAh/cm 3 ), and a low charge/discharge insertion/de-insertion voltage at room temperature make it desirable for many applications, however its large volume expansion (>300%) on cycling, poor capacity retention, and Coulombic inefficiencies have limited its use to date. 1,2 While many possible solutions have been proposed, including electrode surface modification, silicon dilution via creation of a composite anode, e.g. (Si-C), identifying new binders that control the expansion, or new electrode designs that contain the expansion, none alone have met the challenge. 3,4 While several studies have focused on the properties of silicon, its morphology, or its fabrication into an electrode, aspects of its electrochemical cycling, such as Coulombic inefficiencies, are related in part to the system level problem of how the silicon interface interacts with the electrolyte. Edström et al., utilizing Soft X-Ray Photoelectron Spectroscopy, was able to not only track SEI and surface changes within an electrochemical cell but was able to differentiate interfacial reaction products forming on the surface of underlying electrode materials.5 Philippe et al.,...

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Effect of Heat Treatment on Si Electrodes Using Polyvinylidene Fluoride Binder

Cited by 118 publications

References 33 publications

Polyethylenimine nanofibrous adsorbent for highly effective removal of anionic dyes from aqueous solution

Polyethylenimine nanofibrous adsorbent for highly effective removal of anionic dyes from aqueous solution

The emerging era of supramolecular polymeric binders in silicon anodes

Effect of Surface Termination on Electrochemical Performance of Silicon Thin Films

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