The need for viable energy storage technologies is becoming more apparent as the amount of renewable energy being wasted increases. Here, we have provided an in-depth quantification of the theoretical energy storage density possible from redox flow battery chemistries which is essential to understanding the energy storage capacity of a battery system. This improved energy storage density model captures a wide range of conditions and reaction types based on fundamental electrolyte chemistry principles and thermodynamics. The model proposed here Requires standard Gibbs energy, activity coefficients, and state of charge limits. We also demonstrate that energy efficiency values can be incorporated to account for non-thermodynamic contributions. Allvanadium and iron-chromium redox flow battery chemistries were modeled using literature data to confirm the accuracy of the proposed approach. Excellent agreements were obtained between our modeling results and experimental energy storage values obtained from literature. Using this approach, we can precisely quantify the storage capacity possible with new chemistries and assess the tradeoffs we make by enhancing one property at the expense of another.

No abstract

Reliable corrosion monitoring of natural gas transmission lines is a major tool providing a foundation for safe management of natural gas infrastructures. Through the development of membrane-based electrochemical sensors which are able to function in low-conductivity gas environments, corrosion monitoring practices can be further strengthened by real-time monitoring of key risk factors such as relative humidity and corrosion rates of corrodible structures. In this work, we demonstrate and validate how a 4-electrode conductivity sensor can provide a means to monitor relative humidity in gases via electrochemical impedance spectroscopy through finite element analysis (FEA). For a relative humidity range of 5%–55%, the impedance response varied from 1 kΩ to 66 kΩ, showing a high sensitivity for gas humidity. To confirm that the measured impedance values reliably interpreted relative humidity, it was found that precise estimation of the sensor’s cell constant was needed. FEA was used to assess how the cell constant depended on the electrode geometry, membrane geometry, and electrode placement within the sensor. Through this approach, assumptions about the characteristic area and length were validated using electrolyte equipotential and current density vector mapping. This reduced possible cell constant uncertainties by 70%. With a cell constant of 14.84 cm−1, obtained via FEA, membrane conductivity values were in good agreement with published data.

No abstract

No abstract