Ionic Conductivities of Block Copolymer Electrolytes with Various Conducting Pathways: Sample Preparation and Processing Considerations

Young, Wen‐Shiue; Epps, Thomas H.

doi:10.1021/ma300362f

Cited by 146 publications

(177 citation statements)

References 56 publications

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“…The deviation between SAXS and TEM results likely was due to POEM shrinkage under exposure to the electron beam in TEM. 16,50 With the addition of LiCF 3 SO 3 at the salt-doping ratio of [EO] : [Li] ¼ 15 : 1, the primary peak of P(S-OEM) shied to q* ¼ 0.018Å À1 , giving a domain spacing of 34.4 nm. The scattering peaks located at q/q* ¼ 1, O3, 2, O7, and 3 suggest a hexagonally-packed cylinder (HEX) morphology.…”

Section: Resultsmentioning

confidence: 99%

Controlled ionic conductivity via tapered block polymer electrolytes

et al. 2015

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We present the design of novel solid electrolytes using tapered block polymers (TBPs). In this work, we synthesize a series of TBPs via atom transfer radical polymerization (ATRP) consisting of rigid polystyrene and ion-conducting poly(oligo-oxyethylene methacrylate) segments and explore the role of tapered interfaces on ion transport. Previous studies on TBPs have shown that manipulating the taper composition in block polymers can reduce the unfavorable polymer-polymer interactions between blocks, enabling the design for highly-processable (lower order-disorder transition temperature) polymer electrolytes. Herein, we demonstrate that the taper profile and taper volume fraction significantly impact the glass transition temperatures (T g s) in block polymer electrolytes, thus affecting the ionic conductivity. Additionally, we find that the normal-tapered materials with z60 vol% tapering exhibit remarkable improvements in ionic conductivity (increase z190% at 20 C and increase z90% at 80 C) in comparison to their non-tapered counterparts. Overall, our TBPs, with controllable interfacial interactions, present an exciting opportunity for the fabrication of cost-effective, highly-efficient, and stable energy storage membranes.

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Section: Resultsmentioning

confidence: 99%

Controlled ionic conductivity via tapered block polymer electrolytes

et al. 2015

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“…Furthermore, these two blocks could form unique patterns with special pathways to increase ionic conductivities. [55] With these improvements, the ionic conductivity of dual-ion GPEs had reached over 10 −3 S cm −1 , [56][57][58] with the tensile strength over 10 MPa [59,60] and the thermal stability over 400 °C. [61] Recently, some other effective strategies have been further reported by immobilizing anions to realize single lithium-ion conducting GPEs or directly introducing redox-active mediators into GPEs.…”

Section: The Performance Improvement Of the Gpesmentioning

confidence: 99%

Gel Polymer Electrolytes for Electrochemical Energy Storage

Cheng

Pan

Zhao

et al. 2017

Advanced Energy Materials

780

562

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storage devices with adjustable shapes and high flexibility, which is promising for the burgeoning portable and wearable electronics. [7][8][9] Furthermore, the flexibility and elasticity of GPEs are also prone to tolerate the volume change of electrode materials and the dendrites of lithium metal during charge and discharge processes. [10][11][12][13] As a consequence, GPEs have become one of the most desirable alternatives among various electrolytes for the electrochemical energy storage devices, and significant progress has been made in lithium-ion batteries (LIBs), supercapacitors (SCs), lithium-oxygen (Li-O 2 ) batteries as well as the other kinds of electrochemical energy storage devices, such as sodium-ion batteries, lithium-sulfur batteries, fuel cells, and zinc-air batteries. [14][15][16] In order to meet the requirements of wearable devices for flexibility and deformability, more special GPEs with tough, [17] stretchable, [18] and compressible [19] functionalities have been also developed.Typically, a polymeric framework is adopted in GPEs as host material, providing high mechanical integrity. Several criteria for a good polymer host lie in: [20][21][22] (i) fast segmental motion of polymer chain; (ii) special groups promoting the dissolution of salts; (iii) low glass transition temperature (T g ); (iv) high molecular weight; (v) wide electrochemical window; (vi) high degradation temperature. Within the framework, the salts in the GPEs serve as the sources of the charge carriers, which are generally required to have large anions and low dissociation energy for easier dissociating-induced free/mobile ions. According to the types of electrolytes, there are four categories of GPEs based on proton, [23] alkaline, [24] conducting salts, and ionic liquids (ILs). [25] The criteria for an appropriate electrolyte include: [26][27][28] (i) good dissociation without forming ion pairs or ion aggregation; (ii) high thermal, chemical, and electrochemical stability; (iii) high ionic conductivity. In order to dissolve both the polymer hosts and electrolytic salts, the organic/ aqueous solvents are introduced to provide the medium for ionic conduction. A good solvent should simultaneously have high dielectric constant (ɛ > 15), donor number for more dissociation of ion and chemical and electrochemical stability. Organic solvents normally include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dimethyl formamide (DMF), dimethyl sulphoxide, ethyl methyl carbonate, and tetrahydrofuran.To prepare a high-performance GPE, it is essential to select the species of host polymer, solvent, and electrolytic salt, and then blend them by solution or melt processes, such as casting With the booming development of flexible and wearable electronics, their safety issues and operation stabilities have attracted worldwide attentions. Compared with traditional liquid electrolytes, gel polymer electrolytes (GPEs) are preferred due to their higher safety and adaptability to the design of ...

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“…68 In anhydrous ion transport materials, it has been shown that 3-D continuous ionic domains can provide higher conductivity values than 1-D or 2-D channels. 69,70 In water-assisted ion transport materials, experimental comparisons have been conducted on the minor phases in spherical and cylindrical morphologies, together with lamellae, while the matrices of cylindrical and spherical phases were scarcely investigated. This was likely due to the fact that the formation of matrices require a high volume fraction of the ionic block and can lead to excessive hydration and loss of mechanical integrity upon water sorption.…”

Section: ■ Introductionmentioning

confidence: 99%

Achieving Continuous Anion Transport Domains Using Block Copolymers Containing Phosphonium Cations

et al. 2016

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Triblock and diblock copolymers based on isoprene (Ip) and chloromethylstyrene (CMS) were synthesized by sequential polymerization using reversible addition− fragmentation chain transfer radical polymerization (RAFT). The block copolymers were quaternized with tris(2,4,6-trimethoxyphenyl)phosphine (Ar 3 P) to prepare soluble ionomers. The ionomers were cast from chloroform to form anion exchange membranes (AEMs) with highly ordered morphologies. At low volume fractions of ionic blocks, the ionomers formed lamellar morphologies, while at moderate volume fractions (≥30% for triblock and ≥22% for diblock copolymers) hexagonal phases with an ionic matrix were observed. Ion conductivities were higher through the hexagonal phase matrix than in the lamellar phases. Promising chloride conductivities (20 mS/cm) were achieved at elevated temperatures and humidified conditions. ■ INTRODUCTIONAEMs have attracted increasing interests due to numerous applications across many fields, such as photosynthesis, 1 water purification, 2,3 gas separation, 4,5 and alkaline fuel cells. 6−10 Compared to the extensive studies on proton exchange membranes (PEMs), 11 fundamental understanding of the structure−performance relationship in AEMs is urgently needed. This requires well-defined ionic polymers for AEM preparation and investigation. The most widely used strategy of AEMs synthesis is through chemical modification of engineering polymers, such as polysulfone, 12−23 poly(ether ether ketone), 24 polyphenylene, 25−27 and poly(phenylene oxide). 28−33 Other strategies include direct polymerization to synthesize homopolymers 34 or random copolymers. 35−39 In addition, cross-linked materials have also been reported, where better mechanical properties, higher ion content, controlled water sorption, and reduced fuel crossover could be achieved. 40−48 However, although good membrane performance has been achieved, the disordered nature of these materials still hinders a complete understanding of the anion transport mechanism.As demonstrated in PEMs, microphase separation can promote ion transport and water diffusion. 49,50 Recent research has discovered similar effects in AEMs. A few examples of multiblock poly(arylene ether)s were prepared by polycondensation. 51−54 Faster anion transport was observed in ordered structures compared to random copolymer counterparts. Similarly, triblock copolymers with polysulfone as the midblocks were prepared by polymer coupling and displayed improved anion conductivities. 55 Modifying precursor block copolymers via chloromethylation or bromination and subsequent quaternization resulted in ionic copolymers with promising conductivities. 56−58 Knauss et al. 59 and Xu et al. 60 reported block and graft copolymers from end-functionalized poly(phenylene oxide), and good mechanical strengths were achieved together with remarkable anion conductivities. Direct polymerization was utilized to synthesize ionic liquid based poly(methyl methacrylate) block copolymers. 61,62 It was found that in weakly segregated block copo...

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Ionic Conductivities of Block Copolymer Electrolytes with Various Conducting Pathways: Sample Preparation and Processing Considerations

Cited by 146 publications

References 56 publications

Controlled ionic conductivity via tapered block polymer electrolytes

Controlled ionic conductivity via tapered block polymer electrolytes

Gel Polymer Electrolytes for Electrochemical Energy Storage

Achieving Continuous Anion Transport Domains Using Block Copolymers Containing Phosphonium Cations

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