Enhanced Ion Transport Through Mesopores Engineered with Additional Adsorption of Layered Double Hydroxides Array in Alkaline Flow Batteries

Efficient mass transfer in electrodes is essential for the electrochemical processes of battery charge and discharge, especially at high rates and capacities. This study introduces a 3D electrode design featuring layered double hydroxides (LDHs) nanosheets array grown in situ on a carbon felt surface for flow batteries. The mesoporous structure and surface characteristic of LDH nanosheets, especially, the hydroxyl groups forming a unique H-bonding-like geometry with ferrous cyanide ions, facilitate efficient adsorption and ion transport. Thus, the designed LDHs electrode enables the alkaline zinc-iron flow battery to maintain a voltage efficiency of 81.6% at an ultra-high current density of 320 mA cm-2, surpassing the values reported in previous studies. The energy efficiency remains above 84% after 375 cycles at a current density of 240 mA cm-2. Molecular dynamics simulations verify the enhanced adsorption effect of LDH materials on active ions, thus facilitating ion transport in the battery. This study provides a novel approach to improve mass transport in electrodes for alkaline flow batteries and other energy storage devices. A layer of layered double hydroxides nanosheet array (LDH-CF) is first designed to promote the mass transfer process of ions for alkaline zinc-based flow batteries. The designed layered double hydroxides nanosheets array grown in situ on a carbon felt surface with cross-enclosed mesoporous structure and positive surface charge enabling alkaline zinc-based flow batteries with high efficiency at ultra-high current densities, which opens a new avenue for constructing high efficiency zinc-based batteries.image

Automated summary

Efficient mass transfer in electrodes is crucial for battery charge and discharge processes. This study introduces a novel 3D electrode design using layered double hydroxides (LDHs) nanosheets array for flow batteries, which significantly enhances mass transport and ion adsorption. The designed LDH electrode demonstrates high voltage efficiency and energy efficiency even at ultra-high current densities. Molecular dynamics simulations confirm the improved ion transport facilitated by LDH materials. This study offers a new approach to enhance mass transfer in electrodes for alkaline flow batteries and other energy storage devices.