Ionic conductivity in poly (ethylene oxide)- poly (alkylmethacrylate)-block copolymer mixtures with LiI

Lobitz, P.; Füllbier, H.; Reiche, A.; Illner, J. C.; Reuter, H.; Höring, S.

doi:10.1016/0167-2738(92)90008-d

Cited by 34 publications

(15 citation statements)

References 9 publications

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“…T m increases linearly with ϕ c for the SEO x S electrolyte series until the value of the PEO−LiTFSI complex is reached. For the comb PEO, T m remains constant at ∼22.1 ± 2°C, similar to that of the pure A block, cEO 23 , independent of the block copolymer architecture. The degrees of crystallinity of PEO in the linear PEO BCEs are divided into two groups.…”

Section: ■ Results and Discussionmentioning

confidence: 74%

“…For the comb electrolytes, the ionic conductivity also increases linearly with ϕ c until the value of the PEO homopolymer electrolyte is reached. Interestingly, the conductivity of the pure A block, cEO 23 , also belongs to this general trend with an ionic conductivity lower than that of the high-molecular weight amorphous PEO homopolymer electrolyte above its melting temperature. The ionic conductivity of the comb electrolyte is independent of the block copolymer architecture, diblock (B−A) or triblock (B−A−B or A−B−A), and of the BCE molecular weight all over the volume fraction range of the conducting phase with values higher than 10 −4 S cm −1 for ϕ c > 0.5.…”

Section: Chemistry Of Materialsmentioning

confidence: 92%

“…For this purpose, styrene was used in a 5 mol % proportion to combine an efficient polymerization control with a high content of the conductive phase. This A block is abbreviated as cEO 23 because it results in 23 EO units per side chain. The total content of EO in the A block is 86 wt %.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Optimization of Block Copolymer Electrolytes for Lithium Metal Batteries

et al. 2015

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International audienceSafety is one of the most important criteria for electrochemical energy storage devices used in large scale applications such as wind or solar farms. In this context, solid polymer electrolytes based on nanostructured block copolymer electrolytes (BCEs) are promising because their properties can be finely tuned by adjusting simultaneously their block chemistries and polymer architectures. However, there is a need to rationalize the different properties of BCE that are optimal for battery applications. We produced by controlled radical polymerization a large number of BCEs based on either (1) linear poly(ethylene oxide) (PEO) or (2) comb PEO as the ionic conductor block, and polystyrene as the structural block. We varied the molecular weight of the PEO-based block, the composition, and the architecture (diblock vs triblock). We performed a systematic analysis of their thermodynamic, ionic transport, and mechanical properties. To verify the potential of BCEs as electrolytes, we evaluated their electrochemical stabilities. Laboratory scale batteries comprising the best BCEs and LiFePO4 as a positive active material were cycled at different rates and temperatures. This process allows the selection of the best architectures and compositions that had been successfully tested in battery prototypes and cycled for more than 600 cycles at high rates without any dendritic growth

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Section: ■ Results and Discussionmentioning

confidence: 74%

Section: Chemistry Of Materialsmentioning

confidence: 92%

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Optimization of Block Copolymer Electrolytes for Lithium Metal Batteries

et al. 2015

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“…11,12 One approach for resolving this problem is the use of a block copolymer electrolyte. [13][14][15][16][17][18][19][20][21][22] Immiscibility between the blocks induces microphase separation, producing hard insulating phases interspersed with soft, ionically conductive phases. [23][24][25] In studies utilizing block copolymers as solid polymer electrolytes, the mechanical phase is usually made of a high glass transition temperature polymer such as polystyrene.…”

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confidence: 99%

Failure Mode of Lithium Metal Batteries with a Block Copolymer Electrolyte Analyzed by X-Ray Microtomography

Devaux

Harry

Parkinson

et al. 2015

J. Electrochem. Soc.

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Solid block polymer electrolytes are promising candidates for the development of high energy density rechargeable lithium metal based batteries. All solid-state batteries comprising lithium metal negative electrode and lithium iron phosphate (LiFePO 4 ) composite positive electrode were assembled. A polystyrene-b-poly(ethylene oxide) (SEO) copolymer doped with a lithium salt was used as the electrolyte. After cycling the batteries, the reason for capacity fade and failure was determined by imaging the batteries using synchrotron hard X-ray microtomography. These experiments revealed partial delamination of the lithium foil and the block copolymer electrolyte layer. The void volume between the foil and electrolyte layer obtained after 40 to 90 cycles is comparable to volume change in the battery during one cycle. A simple model to account for the effect of delamination on current density in the battery is presented. Capacity fade and battery failures observed in our experiments are consistent with this model. No evidence of lithium dendrite formation was found. In contrast, cycled lithium-lithium symmetric cells with the same polymer electrolyte at the same current density failed due to dendrite formation. No evidence of delamination was found in these cells. Solid polymer electrolytes are promising candidates for the development of high performance rechargeable batteries comprising a lithium (Li) metal electrode due to their chemical stability toward lithium and their mechanical resistance to dendrite growth.1-3 After the pioneering work by Fenton et al., 4 where poly(ethylene oxide) (PEO) laden with alkali metal salts was shown to possess good ionic conductivity, its application as a polymer electrolyte in a full cell was demonstrated by Armand et al. [5][6][7] PEO is a semi-crystalline polymer at room temperature. Ionic transport in PEO electrolytes is linked to segmental motion of the polymer chains, 8,9 and occurs predominantly in the amorphous phase.10 Thus solid polymer electrolyte based batteries must be operated at temperatures (T) above the PEO melting temperature. However, amorphous PEO is too soft to avoid short circuit due to lithium dendrite growth. 11,12 One approach for resolving this problem is the use of a block copolymer electrolyte. [13][14][15][16][17][18][19][20][21][22] Immiscibility between the blocks induces microphase separation, producing hard insulating phases interspersed with soft, ionically conductive phases. [23][24][25] In studies utilizing block copolymers as solid polymer electrolytes, the mechanical phase is usually made of a high glass transition temperature polymer such as polystyrene. [26][27][28][29] Extensive work on the thermodynamics of polystyrene-b-poly(ethylene oxide) (SEO) diblock copolymers [30][31][32][33] indicate that the tendency for microphase separation is enhanced by the presence of ions. 34,35 For symmetric SEO electrolytes, i.e. copolymers wherein the volume fraction of the conducting phase is above 50%, the ionic conductivity has been shown to increase wit...

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“…In contrast, σ of PEO homopolymers decreases with increasing molecular weight, reaching a plateau as the molecular weight of the PEO block exceeds 4 kg/mol [9]. Beyond PS-based block copolymers, a wide range of different amorphous polymers [34][35][36][37][38][39] has been considered for use as the structural block. …”

Section: Introductionmentioning

confidence: 99%

Investigating polypropylene-poly(ethylene oxide)-polypropylene triblock copolymers as solid polymer electrolytes for lithium batteries

et al. 2014

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Syndiotactic polypropylene-b-poly(ethylene oxide)-b-syndiotactic polypropylene (PEOP) triblock copolymers were synthesized and solid polymer electrolytes were prepared by mixing with lithium bis(trifluoromethane) sulfonimide (LiTFSI) salt. PEOP formed strongly-segregated morphologies in the absence and presence of LiTFSI. LiTFSI inhibited poly(ethylene oxide) crystallization without affecting polypropylene crystallinity. The conductivity exhibited a non-monotonic dependence on molecular weight (M n ) with a maximum near 20 kg/mol. In contrast, polystyrene-b-poly(ethylene oxide) electrolytes exhibit conductivity increasing monotonically with M n , up to a plateau in the high-M n limit. This suggests that non-conducting semi-crystalline microphases interfere with conducting pathways, while non-conducting amorphous microphases formed well-connected conducting pathways.Published by Elsevier B.V.

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Ionic conductivity in poly (ethylene oxide)- poly (alkylmethacrylate)-block copolymer mixtures with LiI

Cited by 34 publications

References 9 publications

Optimization of Block Copolymer Electrolytes for Lithium Metal Batteries

Optimization of Block Copolymer Electrolytes for Lithium Metal Batteries

Failure Mode of Lithium Metal Batteries with a Block Copolymer Electrolyte Analyzed by X-Ray Microtomography

Investigating polypropylene-poly(ethylene oxide)-polypropylene triblock copolymers as solid polymer electrolytes for lithium batteries

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