Synergistic deficiency and heterojunction engineering boosted VO2 redox kinetics for aqueous zinc-ion batteries with superior comprehensive performance

Adjusting the Valence State of Vanadium in VO2(B) by Extracting Oxygen Anions for High‐Performance Aqueous Zinc‐Ion Batteries

“…Additionally, electron paramagnetic resonance (EPR) spectroscopy often was applied to determine the interaction between unpaired electrons and their surrounding environment [12b] . VO 2– x has sharp and strong symmetric peaks (Figure 1k), arising from electrons captured at the defect sites of VO 2– x ( g =1.96), which is usually considered as the direction of anion vacancies and in accordance with prior reports [4b,18] …”

“…Significant performance improvement was observed at 0.1 A g −1 and it can be seen that VO 2 //Zn batteries have faster capacity fading tendency after about 20 cycles. However, the VO 2– x //Zn batteries not only show much higher specific capacity, but also improved high cycling stability over the former after the first 5 cycles (Figure 2b,c), indicating the oxygen vacancies of VO 2– x can provide more capacity from highly reversible adsorption/desorption process [18] . The charge–discharge curves of VO 2 and VO 2– x were almost identical in shape.…”

“…In addition, the rate capacities were also tested at current densities of 0.1, 0.3, 0.5, 0.8, 1, 2, 3, 4, and 5 A g −1 ; subsequently, the current density was decreased to 3 A g −1 and the specific capacities of both the samples, which had reverted to their original states, were measured (Figure 2d and Figure S4). Figure 2e shows the excellent long‐term cycling stability at 3 A g −1 after the slight capacity fading at initial cycles, which could be associated with the electrochemical activation and common on the electrode [18,19] . Moreover, we tested the Nyquist plots of Zn//VO 2– x batteries at different cycles (Figure S5).…”

Nanosized monometallic selenides heterostructures implanted into metal organic frameworks-derived carbon for efficient lithium storage

“…Obviously, the Se 3d spectra in NiSe/NiSe2@C exhibit significantly positive shift (~0.30 eV for Se 2and ~0.88 eV for Se -) compared with NiSe@C and slightly negative shift (~0.26 eV for Se 2and 0.20 eV for Se -) compared with NiSe2@C, again indicating interfacial interaction at the heterogeneous boundary and the establishment of strong coupled interface [30]. The electrons transfer from NiSe to NiSe2 is induced by the lattice defect and distortions at two-phase boundary and could cause interfacial charge redistribution, which are beneficial for Li + ions transportation and improved reaction kinetics [16,31].…”

Zinc Ion Thermogalvanic Cell: A New Strategy for Low-Grade Heat Conversion and Energy Storage

“…This signi cant difference between PC and VO 2 -PC may be highly in uenced by their different charge storage mechanisms. As discussed above, the inserted Zn 2+ can react with the VO 2 and achieve stable bonding in the form of chemical bonds 19. Thus, a large plenty of heat is required to release such combined Zn 2+ , which also implies a high energy input.…”