Rechargeable batteries are highly promised to accomplish targets of sustainable transition, but their performance, especially in efficiency, power and energy densities remains improving. The essential problems of the interface performance between porous carbon electrodes and electrolytes are critical for battery performance promotion, which we tackle challenges and applied three types of rechargeable batteries in research. First, we design carbon nanofiber electrodes to boost the energy efficiency of vanadium redox flow batteries. Optimizing the microstructure of low-cost electrospun nanofibers allows us to achieve a large surface area and an abundance of mesopores, leading to a high catalytic activity for battery reactions. Second, we tackle the issue of solid iodine passivation, a cri...[ Read more ]

Rechargeable batteries are highly promised to accomplish targets of sustainable transition, but their performance, especially in efficiency, power and energy densities remains improving. The essential problems of the interface performance between porous carbon electrodes and electrolytes are critical for battery performance promotion, which we tackle challenges and applied three types of rechargeable batteries in research. First, we design carbon nanofiber electrodes to boost the energy efficiency of vanadium redox flow batteries. Optimizing the microstructure of low-cost electrospun nanofibers allows us to achieve a large surface area and an abundance of mesopores, leading to a high catalytic activity for battery reactions. Second, we tackle the issue of solid iodine passivation, a critical yet overlooked interfacial phenomenon in aqueous iodine-flow batteries. We first confirm its role in limiting the charging current of the batteries via voltametric measurements, which together with spectroscopic rate measurements allow us to derive the rate constant of solid iodine dissolution based on an interface-controlled kinetics model. To boost the kinetics, we screen common organic solvents and identify acetonitrile as a cosolvent. Calculations reveal their role as weakening the interaction between iodine and the electrode surface. Finally, we scrutinize the interaction between iodine and carbon in lithium iodine batteries to address the limits of the specific capacity and stability of the iodine cathode. By comparing theoretical charge-storage models with experimental results, we reveal that the cathode stores charge via iodine-adsorption to high-specific area porous carbon electrodes. Thus, reduction treatment methods are applied to improve cathode performance.

The work in the thesis applies mechanistic insights to identify and address limiting factors of rechargeable batteries for fulfilling their promises of efficient, affordable energy storage.