Charging toward improved lithium-ion polymer electrolytes: exploiting synergistic experimental and computational approaches to facilitate materials design

Ketkar, Priyanka M.; Shen, Kuan-Hsuan; Hall, Lisa M.; Epps, Thomas H.

doi:10.1039/c8me00105g

Cited by 44 publications

(67 citation statements)

References 131 publications

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“…Regarding the polymer electrolytes or organic ion conductors, such as OIPCs, the use of MD is more prevalent. In recent years, computational studies are increasingly being undertaken and provide significant insights into the study of solid electrolyte systems . Here, we mainly focus on recent progress in computational studies of organic ionic plastic crystals and polymer electrolytes.…”

Section: Simulation‐assisted Design Of New Solid‐state Electrolytesmentioning

confidence: 99%

Toward High‐Energy‐Density Lithium Metal Batteries: Opportunities and Challenges for Solid Organic Electrolytes

et al. 2020

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.201905219.With increasing demands for safe, high capacity energy storage to support personal electronics, newer devices such as unmanned aerial vehicles, as well as the commercialization of electric vehicles, current energy storage technologies are facing increased challenges. Although alternative batteries have been intensively investigated, lithium (Li) batteries are still recognized as the preferred energy storage solution for the consumer electronics markets and next generation automobiles. However, the commercialized Li batteries still have disadvantages, such as low capacities, potential safety issues, and unfavorable cycling life. Therefore, the design and development of electromaterials toward high-energy-density, long-life-span Li batteries with improved safety is a focus for researchers in the field of energy materials. Herein, recent advances in the development of novel organic electrolytes are summarized toward solid-state Li batteries with higher energy density and improved safety. On the basis of new insights into ionic conduction and design principles of organic-based solid-state electrolytes, specific strategies toward developing these electrolytes for Li metal anodes, high-energy-density cathode materials (e.g., high voltage materials), as well as the optimization of cathode formulations are outlined. Finally, prospects for next generation solid-state electrolytes are also proposed.

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Section: Simulation‐assisted Design Of New Solid‐state Electrolytesmentioning

confidence: 99%

Toward High‐Energy‐Density Lithium Metal Batteries: Opportunities and Challenges for Solid Organic Electrolytes

et al. 2020

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“…is this: what is the sequence of monomers that will give the most efficacious polymer electrolyte. [11] Before attempting to answer this question, it is important to agree on the definition of electrolyte efficacy.…”

Section: Introductionmentioning

confidence: 99%

Diffusion and migration in polymer electrolytes

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Halat

Villaluenga

et al. 2020

Progress in Polymer Science

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Mixtures of neutral polymers and lithium salts have the potential to serve as electrolytes in next-generation rechargeable Li-ion batteries. The purpose of this review is to expose the delicate interplay between polymer-salt interactions at the segmental level and macroscopic ion transport at the battery level. Since complete characterization of this interplay has only been completed in one system: mixtures of poly(ethylene oxide) and lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI), we focus on data obtained from this system. We begin with a discussion of the activity coefficient, followed by a discussion of six different diffusion coefficients: the Rouse motion of polymer segments is quantified by Dseg, the self-diffusion of cations and anions is quantified by Dself,+ and Dself,-, and the build-up of concentration gradients in electrolytes under an applied potential is quantified by Stefan-Maxwell diffusion coefficients, 0+ , 0− , and +−. The Stefan-Maxwell diffusion coefficients can be used to predict the velocities of the ions at very early times after an electric field is applied across the electrolyte. The surprising result is that 0− is negative in certain concentration windows. A consequence of this finding is that at these concentrations, both cations and anions are predicted to migrate toward the positive electrode at early times. We describe the controversies that surround this result. Knowledge of the Stefan-Maxwell diffusion coefficients enable prediction of the limiting current. We argue that the limiting current is the most important characteristic of an electrolyte. Excellent agreement between theoretical and experimental limiting current is seen in PEO/LiTFSI mixtures. What sequence of monomers that, when polymerized, will lead to the highest limiting current remains an important unanswered question. It is our hope that the approach presented in this review will guide the development of such polymers.

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“…The major difference to liquids is that the ions move via hopping from coordination site to coordination site or from cluster to cluster [45,46]. Factors playing a role can be summarized to be (i) segmental dynamics of the polymer; (ii) cation solvation dynamics (of the conducting salt), cation-anion interactions, and (iii) solvation-site connectivity [47,48].…”

Section: Introductionmentioning

confidence: 99%

In Situ Preparation of Crosslinked Polymer Electrolytes for Lithium Ion Batteries: A Comparison of Monomer Systems

et al. 2020

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Solid polymer electrolytes for bipolar lithium ion batteries requiring electrochemical stability of 4.5 V vs. Li/Li+ are presented. Thus, imidazolium-containing poly(ionic liquid) (PIL) networks were prepared by crosslinking UV-photopolymerization in an in situ approach (i.e., to allow preparation directly on the electrodes used). The crosslinks in the network improve the mechanical stability of the samples, as indicated by the free-standing nature of the materials and temperature-dependent rheology measurements. The averaged mesh size calculated from rheologoical measurements varied between 1.66 nm with 10 mol% crosslinker and 4.35 nm without crosslinker. The chemical structure of the ionic liquid (IL) monomers in the network was varied to achieve the highest possible ionic conductivity. The systematic variation in three series with a number of new IL monomers offers a direct comparison of samples obtained under comparable conditions. The ionic conductivity of generation II and III PIL networks was improved by three orders of magnitude, to the range of 7.1 × 10−6 S·cm−1 at 20 °C and 2.3 × 10−4 S·cm−1 at 80 °C, compared to known poly(vinylimidazolium·TFSI) materials (generation I). The transition from linear homopolymers to networks reduces the ionic conductivity by about one order of magnitude, but allows free-standing films instead of sticky materials. The PIL networks have a much higher voltage stability than PEO with the same amount and type of conducting salt, lithium bis(trifluoromethane sulfonyl)imide (LiTFSI). GII-PIL networks are electrochemically stable up to a potential of 4.7 V vs. Li/Li+, which is crucial for a potential application as a solid electrolyte. Cycling (cyclovoltammetry and lithium plating-stripping) experiments revealed that it is possible to conduct lithium ions through the GII-polymer networks at low currents. We concluded that the synthesized PIL networks represent suitable candidates for solid-state electrolytes in lithium ion batteries or solid-state batteries.

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Charging toward improved lithium-ion polymer electrolytes: exploiting synergistic experimental and computational approaches to facilitate materials design

Abstract: Lithium-ion battery performance is governed by ionic transport mechanisms over a wide range of size scales.

Cited by 44 publications

References 131 publications

Toward High‐Energy‐Density Lithium Metal Batteries: Opportunities and Challenges for Solid Organic Electrolytes

Toward High‐Energy‐Density Lithium Metal Batteries: Opportunities and Challenges for Solid Organic Electrolytes

Diffusion and migration in polymer electrolytes

In Situ Preparation of Crosslinked Polymer Electrolytes for Lithium Ion Batteries: A Comparison of Monomer Systems

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