Investigation of Fe-Ni Battery/Module for Grid Service Duty Cycles.

Iron-nickel (Fe-Ni) batteries are renowned for their durability and resilience against overcharging and operating temperatures. However, they encounter challenges in achieving widespread adoption for energy storage applications due to their low efficiency and the need for regular maintenance and electrolyte replacement, which adds to maintenance costs. This study evaluates and demonstrates the capabilities of Fe-Ni batteries for participating in grid energy storage applications. Stable performance was observed frequency regulation (FR) testing at 100% and 50% state of charge (SOC)s, while at 50% SOC, there was a 14% increase in efficiency compared to 100% SOC. Although 25% SOC achieved higher efficiency, limited cyclability was observed due to reaching the discharge cutoff voltage. Optimal SOC selection, battery monitoring, maintenance, and appropriate charging strategies of Fe-Ni batteries seem to be crucial for their FR applications. Fe-Ni batteries exhibit stable peak shaving (PS) results, indicating their suitability and reliability under various load conditions for PS testing. Extended cycling tests confirm their potential for long-term grid-scale energy storage, enhancing their appeal for PS and FR applications.

An ultra-stable reference electrode for scaled all-vanadium redox flow batteries.

Redox flow batteries (RFBs) have been investigated as a promising energy storage system (ESS) for grid applications over the past several decades due to their unique features, which include the separation of energy and power output, high safety, and long cycle life. It is therefore vital but still in severe deficiency to understand the reliability of RFBs, and the mechanisms that cause degradation with time. One of the primary challenges involves the unseparated contributions from individual electrodes due to the absence of a stable reference electrode (RE), particularly for long-term cycle testing in a scaled cell. Herein, we first develop an ultra-stable RE for scaled all-vanadium RFBs. The newly developed RE, based on a dynamic hydrogen electrode (DHE) with a novel design on the area (size) and surface roughness of platinum electrodes, demonstrates high accuracy and long-term stability that enables in situ monitoring of individual electrode potentials throughout 500 cycles. By introducing the RE approach to decouple the cathode and anode in conjunction with the measurement of voltage profiles, overpotentials and polarization curves, the reliability and degradation mechanism of a scaled all-vanadium RFB are further explored, revealing the diverse behaviors of individual electrodes. This exploratory work will benefit the future design and development of a stable RE for a scaled ESS, as well as the fundamental understanding of the RFB's reliability and degradation mechanism.

Quantifying the effect of polymer blending through molecular modelling of cyanurate polymers.

Modification of polymer properties by blending is a common practice in the polymer industry. We report here a study of blends of cyanurate polymers by molecular modelling that shows that the final experimentally determined properties can be predicted from first principles modelling to a good degree of accuracy. There is always a compromise between simulation length, accuracy and speed of prediction. A comparison of simulation times shows that 125ps of molecular dynamics simulation at each temperature provides the optimum compromise for models of this size with current technology. This study opens up the possibility of computer aided design of polymer blends with desired physical and mechanical properties.