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Title: Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry

Abstract

The ultimate objectives of this research are to understand the principles underpinning nano-composite polymer electrolytes (CPEs) and facilitate development of novel CPEs that are low-cost, have high conductivities, large Li+ transference numbers, improved electrolyte-electrode interfacial stability, yield long cycle life, exhibit mechanical stability and are easily processable. Our approach is to use nanoparticulate silica fillers to formulate novel composite electrolytes consisting of surface-modified fumed silica nano-particles in polyethylene oxides (PEO) in the presence of lithium salts. We intend to design single-ion conducting silica nanoparticles which provide CPEs with high Li+ transference numbers. We also will develop low-Mw (molecular weight), high-Mw and crosslinked PEO electrolytes with tunable properties in terms of conductivity, transference number, interfacial stability, processability and mechanical strength

Authors:
;
Publication Date:
Research Org.:
North Carolina State University; Michigan State Univ., East Lansing, MI (United States)
Sponsoring Org.:
USDOE - Office of Energy Research (ER)
OSTI Identifier:
897873
Report Number(s):
DOE/ER/15248-final
TRN: US200709%%442
DOE Contract Number:
FG02-01ER15248
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPOSITE MATERIALS; NANOSTRUCTURES; ELECTROCHEMISTRY; ELECTROLYTES; FILLERS; POLYETHYLENE GLYCOLS; RHEOLOGY; SILICA; SYNTHESIS; LITHIUM COMPOUNDS; electrolytes, nanocomposite

Citation Formats

Khan, Saad A.: Fedkiw Peter S., and Baker, Gregory L. Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry. United States: N. p., 2007. Web. doi:10.2172/897873.
Khan, Saad A.: Fedkiw Peter S., & Baker, Gregory L. Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry. United States. doi:10.2172/897873.
Khan, Saad A.: Fedkiw Peter S., and Baker, Gregory L. Wed . "Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry". United States. doi:10.2172/897873. https://www.osti.gov/servlets/purl/897873.
@article{osti_897873,
title = {Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry},
author = {Khan, Saad A.: Fedkiw Peter S. and Baker, Gregory L.},
abstractNote = {The ultimate objectives of this research are to understand the principles underpinning nano-composite polymer electrolytes (CPEs) and facilitate development of novel CPEs that are low-cost, have high conductivities, large Li+ transference numbers, improved electrolyte-electrode interfacial stability, yield long cycle life, exhibit mechanical stability and are easily processable. Our approach is to use nanoparticulate silica fillers to formulate novel composite electrolytes consisting of surface-modified fumed silica nano-particles in polyethylene oxides (PEO) in the presence of lithium salts. We intend to design single-ion conducting silica nanoparticles which provide CPEs with high Li+ transference numbers. We also will develop low-Mw (molecular weight), high-Mw and crosslinked PEO electrolytes with tunable properties in terms of conductivity, transference number, interfacial stability, processability and mechanical strength},
doi = {10.2172/897873},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 24 00:00:00 EST 2007},
month = {Wed Jan 24 00:00:00 EST 2007}
}

Technical Report:

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  • The goal of the synthesis research was to devise routes to PEG/fumed silica/lithium salt composites that can be processed and then photochemically cross-linked to form mechanically stable electrolytes. An essential feature of the system is that the ionic conductivity and the mechanical properties must be de-coupled from each other, i.e., cross-linking of the fumed silica matrix must not cause a significant deterioration of the conductivity of the composite. As shown in Figure 2, we prepared a range of surface-modified fumed silicas and investigated their ability to form mechanically stable composite electrolytes. The groups used to modify the surface properties ofmore » the silica ranged from simple linear alkyls that render the silica hydrophobia to polyethers that promote compatibility with the electrolyte. From these materials we developed a cross-linkable system that satisfies the criteria of processibility and high-conductivity. The key material needed for the cross-linking reaction are silicas that bear surface-attached monomers. As shown schematically in Figure 3a, we prepared fumed silicas with a combination of surface groups, for example, an octyl chain with different coverages of tethered methacrylates. The length of the tether was varied, and we found that both C{sub 3} and C{sub 8} tethers gave useful composites. The functionalized silicas were combined with PEG-DM, AIBN or benzophenone (free radical initiators), LiClO{sub 4} or Li imide, and either methyl, butyl, or octyl, methacrylate to form stable clear gels. Upon irradiation with UV light, polymerization of both the tethered methacrylate and the added methacrylate took place, yielding a cross-linked rubbery composite material. Ionic conductivity measurements before and after cross-linking showed only a slight decrease (see Figure 9 later), thereby offering strong experimental evidence that the mechanical properties conferred by the silica matrix are de-coupled from the ionic conductivity of the PEG-DM matrix.« less
  • Adventitious defects within self-assembled monolayers of 1-octadecanethiol confined to Au substrate have been studied by a new method which takes advantage of the high spatial resolution of scanning tunneling microscopy (STM) and the molecular specificity of electrochemistry. The method permits direct visualization of the defect density and provides information about the chemical and structural nature of the defects. CN- was used to electrochemically etch Au from surface regions near defects. This leads to the formation of triangular etch pits, which exhibit a uniform in-plane orientation. A point-defect model is proposed to explain the orientation of the triangular pits. The modelmore » also predicts that the organomercaptan molecules occupy particular three-fold hollow sites.« less
  • No abstract prepared.
  • This paper explains the technology developed to produce Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) for mercury removal from aqueous wastewater and from organic wastes. The characteristics of SAMMS materials, including physical characteristics and mercury loading, and its application for mercury removal and stabilization are discussed. Binding kinetics and binding speciations are reported. Preliminary cost estimates are provided for producing SAMMS materials and for mercury removal from wastewater. The characteristics of SAMMS in mercury separation were studied at PNNL using simulated aqueous tank wastes and actual tritiated pump oil wastes from Savannah River Site; preliminary results are outlined. 47 refs., 16more » figs., 16 tabs.« less
  • A number of engineered forms such as flexible extrudates, beads, and rods were fabricated using thiol-SAMMS (Self-Assembled Monolayers on Mesoporous Silica) and tested for their mercury adsorption capacities. The flexible extrudate form had a mercury adsorption capacity of 340 mg/g but was found to be structurally unstable. A structurally sound bead form of thiol-SAMMS was fabricated with 5, 10, 25, and 40% by weight clay binder (attapulgite) and successfully functionalized. A structurally stable but non-optimized rod form of thiol-SAMMS was also fabricated. Bench-scale processes were developed to silanize and functionalize mesoporous silica beads made with attapulgite clay binder. Contact anglemore » measurements were conducted to assess the degree of surface coverage by functional groups on mesoporous silica materials.« less