Zincophilic CuO as electron sponge to facilitate dendrite-free zinc-based flow battery

- DFT Calculations of Hydration Effects on Zinc Adsorption and Growth on CuO and Graphite Surfaces - Voltage profiles of galvanostatic Zn deposition on metal oxides - High-magnification SEM images of surface morphology of prepared CuO-graphite - Voltage profiles of galvanostatic Zn deposition on CuO particles with different sizes at current density of 20 mA cm−2 - At different current densities of 10 – 60 mA cm−2, voltage profiles of galvanostatic Zn deposition on (a) b-graphite and (b) CuO-graphite. - Density of states and atomic structures of (a, b) CuO, (c, d) graphite, and (e, f) Zn atom in the box. - Top view of atomic structures used for electronic structure analysis. a, b Zn atom (Zn_1^*) adsorbed on substrate [(a) CuO (001), (b) graphite]. c, d Zn cluster (Zn_3^*) on substrate [(c) CuO (001), (d) graphite]. e, f covered Zn* on substrate [(e) CuO (001), (f) graphite]. The periodic boundary cells are marked with black frame in the figures. - a-c Atomic structures and density of states per layer of (a) CuO (001) slab; and Zn single atom (Zn_1^*) adsorbed on (b) fixed CuO slab and (c) relaxed CuO slab. - a Density of states of oxygen and b top view of atomic structure. - CV tests at scan rate of 20 mV s−1 with a potential range from −0.6 to −1.1 V on (a) b-graphite and (b) CuO-graphite in two different electrolytes: a 0.5 M Na2SO4 electrolyte and a 2.5 M ZnI2 electrolyte. - Chronoamperometry curves obtained under range of applied overpotentials of 100 – 300 mV for (a) b-graphite and (b) CuO-graphite. - Atomic structures and density of states per layer of Zn cluster (Zn_3^*) adsorbed on (a) fixed CuO (001) slab and (b) relaxed CuO (001) slab. - Atomic structures and density of states per layer of (a) CuO (001) slab and of covered Zn* on (b) fixed CuO (001) slab and (c) relaxed CuO (001) slab. - Atomic structures and density of states per layer of (a) graphite slab and Zn atom (Zn_1^*) adsorbed on (b) fixed graphite slab and (c) relaxed graphite slab. - Atomic structures and density of states per layer of Zn cluster (Zn_3^*) adsorbed on (a) fixed graphite slab and (b) relaxed graphite slab. - Atomic structures and density of states per layer of (a) graphite slab and covered Zn* on (b) fixed graphite slab and (c) relaxed graphite slab. - Bader charge analysis of adsorbed Zn atom (Zn_1^*) on substrates [(a) CuO (001), (b) graphite], Zn cluster (Zn_3^*) on substrates [(c) CuO (001), (d) graphite], and covered Zn* on substrates [(e) CuO (001), (f) graphite]. - Overall surface optical images and low-magnification SEM images of Zn electrodeposits on (a) b-graphite and (b) CuO-graphite after charging to 160 mAh cm−2 at a current density of 80 mA cm−2. - Charge-discharge voltage profiles and efficiencies for CuO-graphite with electrolyte of 1.67 M ZnI2 and 4.0 M NH4I at different current densities in range of 20 – 80 mA cm−2. - Schematic diagram of sequential adsorption of Zn atom on CuO (001). Relative energy values of unstable structure (gray), and average values (black). The most stable structures and Zn on Zn* structures are colored blue and red. - Schematic diagram of sequential adsorption of Zn atom on graphite. Relative energy of unstable structures (gray), and average values (black). The most stable structures and Zn on Zn* structures are colored blue and red. - Charge-discharge voltage profiles at constant current density of 20 mA cm−2 for (a) b-graphite and (b) CuO-graphite. The experiment was repeated three times under the same conditions. - Charge-discharge voltage profiles at different current densities in range of 40 – 400 mA cm−2 for (a) b-graphite and (b) CuO-graphite. - Discharge polarization and power density curves of CuO-graphite as function of current density at 70% SoC with electrolyte of 1.67 M ZnI2 and 4.0 M NH4I. - Variation in average charge-discharge potentials under constant current density of 140 mA cm−2. An enlarged plot of coulombic efficiency and energy efficiency from Fig. 6d for improved visibility. Charge-discharge voltage profiles for b-graphite during 1000 cycles and CuO-graphite during 2500 cycles. - High magnification SEM images of surface morphology, and corresponding EDX elemental maps of CuO-graphite electrode (a) before cycling and (b) after 2500th cycles. - High-resolution TEM images, electron diffraction patterns, and corresponding EDX elemental maps of CuO-graphite electrode (a) before cycling and (b) after 2500th cycles. - XRD patterns of CuO-graphite electrode before cycling and after 2500th cycles. - Overall surface images of (a) b-graphite and (b) CuO-graphite electrodes, after charging during 1000 cycles. (c) High-magnification SEM images of two selected areas in Figure (a). - XRD patterns of Zn electrodeposits on (a) b-graphite and (b) CuO-graphite electrodes at 100th, 500th, and 1000th cycles during long-term cycling test.