Electrode−electrolyte interfaces (EEIs) affect the rate capability, cycling stability, and thermal safety of lithium-ion batteries (LIBs). Designing stable EEIs with fast Li + transport is crucial for developing advanced LIBs. Here, we study Li + kinetics at EEIs tailored by three nanoscale polymer thin films via chemical vapor deposition (CVD) polymerization. Small binding energy with Li + and the presence of sufficient binding sites for Li + allow poly(3,4-ethylenedioxythiophene) (PEDOT) based artificial coatings to enable fast charging of LiCoO 2 . Operando synchrotron X-ray diffraction experiments suggest that the superior Li + transport property in PEDOT further improves current homogeneity in the LiCoO 2 electrode during cycling. PEDOT also forms chemical bonds with LiCoO 2 , which reduces Co dissolution and inhibits electrolyte decomposition. As a result, the LiCoO 2 4.5 V cycle life tested at C/2 increases over 1700% after PEDOT coating. In comparison, the other two polymer coatings show undesirable effects on LiCoO 2 performance. These insights provide us with rules for selecting/designing polymers to engineer EEIs in advanced LIBs.

Measuring the thermal conductivity of oxidative chemical vapor deposited poly(3,4-ethylenedioxythiophene) thin films.

The effect of electromagnetic fields on nanoscale atomic structure was determined using synchrotron X-ray pair distribution function (PDF) analysis.

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In situ pair distribution function analysis reveals that electromagnetic radiation exposure during SnO2 nanoparticle growth alters local atomic structure and the synthetic pathway compared to conventional hydrothermal synthesis routes.

Electromagnetic (EM) fields can trigger a range of surprising responses in materials. Microwave radiation (MWR), a type of EM field in the frequency range of 0.3–300 GHz, can lower the synthesis temperature required for ceramics such as TiO2 and induces mixed amorphous–crystalline phase compositions. To better understand the effects of MWR on matter, structural changes during microwave heating and MWR‐assisted synthesis using in situ synchrotron X‐ray diffraction are studied. Anisotropic expansion–contraction of lattice parameters under microwave‐radiation is observed, which contradicts the results from conventional thermal heating. When as‐received TiO2 powders are heated with MWR, an instantaneous decrease in the intensities of diffraction peaks indicates decrystallization/amorphization. High‐resolution electron microscopy supports these observations. Raman spectroscopy and X‐ray photoemission spectroscopy indicate increased defect‐generation under microwave exposure. Molecular dynamics simulations on the anatase phase of TiO2 suggests that introducing an oxygen vacancy can lead to the formation of an interstitial–vacancy pair resulting in anisotropic expansion–contraction of the lattice. These unique responses of ceramics under externally applied fields provide direct evidence for nonthermal coupling between EM fields and matter. Understanding such nonthermal, field‐driven processes has implications in engineering low‐temperature processes for integrating ceramics with polymers for flexible electronics, energy harnessing, and storage applications.

We designed experiments to determine optimized values for input parameters such as temperature, solution concentration, and power input for synthesizing ceramic materials, specifically titanium dioxide (TiO2) thin films using microwave radiation, which permits crystallization of these films at significantly lower temperatures (150‐160 °C) compared to conventional techniques (>450 °C). The advantage of using lower temperatures is both reduced energy requirements, and in expanding the set of substrates (e.g., plastics) on which the thin film materials can be deposited. Low temperature crystallization permits ceramic thin film materials to be directly grown on delicate plastic substrates (which melt at temperatures over 200°C) and thus would have important applications in the emerging flexible electronics industry.Using a linear regression with quadratic terms, we found estimated optimal settings for the reaction parameters. When tried experimentally, these optimal settings produced better results (% coverage with film) than any of the data used in estimation. This approach allows fine tuning of the input parameters and can lead to reliable synthesis of films in a low‐temperature environment. It may also be an important step in understanding the fundamental mechanisms underlying the growth of these films in the presence of electromagnetic fields like microwave radiation. Copyright © 2017 John Wiley & Sons, Ltd.

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