A Multifunctional Anti-Proton Electrolyte for High-Rate
A Multifunctional Anti-Proton Electrolyte for High-Rate – Large volumetric expansion of cathode hosts and sluggish transport kinetics within the cathode–electrolyte interface, also as dendrite growth and hydrogen evolution at Zn anode side are considered as the system problems that cause the electrochemical failure of aqueous Zn-vanadium oxide battery. during this work, a multifunctional anti-proton electrolyte was proposed to synchronously solve all those issues. Theoretical and experimental studies confirm that PEG 400 additive can regulate the Zn2+ solvation structure and inhibit the ionization of free water molecules of the electrolyte.
Then, smaller lattice expansion of vanadium oxide hosts and fewer associated by-product formation can be realized by using such electrolyte. Besides, such electrolyte is additionally beneficial to guide the uniform Zn deposition and suppress the side reaction of hydrogen evolution. due to the integrated synergetic modification, a high-rate and ultrastable aqueous Zn-V2O3/C battery are often constructed, which may remain a specific capacity of 222.8 mAh g−1 after 6000 cycles at 5 A g−1, and 121.8 mAh g−1 even after 18,000 cycles at 20 A g−1, respectively.
The increasing energy crisis and environmental pollution promote the continual exploration of green energy storage solution. Rechargeable aqueous zinc-ion batteries (AZIBs) are alleged to be the potential next-generation candidate benefited from the low cost, intrinsic safety and high theoretical capacity, which have received extensive attention within the recent years.
To develop high-rate and long shelf-life AZIBs, many sorts of cathode materials have been successively demonstrated, which mainly includes the manganese-based oxides [4,5,6,7], vanadium-based compounds [8, 9], Prussian blue analogues (PBAs) [10, 11] and organic materials . Among them, vanadium oxides (such as V2O5, VO2, V2O3) are considered because the promising storage host due to the abundant valence state to achieve high specific capacity, and open-frameworks assembled by various coordination polyhedral to facilitate the efficient ion storage during the electrochemical cycling .
V2AlC (11 technology co.,LTD.), 30% H2O2 (XILONG SCIENTIFIC), Zn(OTf)2 (> 98%, TCI), LiF (99.9% Macklin), 12 mol mL−1 HCL (38 wt% Hushi reagent), H2C2O4 (> 99.5%, Tianjin Baishi Chemical), V2O5 (99%, Xiya reagent), polyethylene glycol 400 (PEG 400, TCI), polyvinylidene fluoride (PVDF, arkema), acetylene black (KJ MTI), and 1-Methyl-2-pyrrolidinone (NMP, > 98%, Aladdin) were purchased and directly used without further purification.
Synthesis of V 2 CT x MXene Nanosheets
V2CTx nanosheets were prepared via etching the V2AlC powder by using lithium fluoride (LiF)/hydrochloric acid (HCl) solution. In detail, 1.0 g of V2AlC powder was slowly added into LiF/HCl solution (2.0 g LiF dispersed into 30 mL of 12 M HCl) within 10 min, which was continuously stirred for 0.5 h at 25 °C. Afterward, the turbid suspension was transferred to a 50 mL teflon-lined stainless-steel autoclave and sealed at 120 °C for 36 h. The turbid suspension was centrifuged to gather the sediments, followed by washing with deionized water for several times until the pH turned neutral. The sediments were further rinsed by ethanol for 3 times before vacuum-drying at 60 °C for 12 h, and eventually receiving the V2CTx nanosheets.
Synthesis of V 2 O 3 /C Nanosheets
2 mL of three 0 wt% H2O2 diluted into 20 mL of 3 wt% H2O2 was dropwise added into 100 mL of ~ 2.0 mg mL−1 V2CTx suspension under vigorous stirring. The mixture was kept stirring for 10 min, and subsequently immersed into nitrogen . After the dispersion was completely frozen, it had been subjected to a vacuum freeze drier for at least 36 h. The obtained powder was annealed at 800 °C for two h with a ramping rate of 5 °C min−1 under Ar/H2 (95/5, vol/vol) flow, leading to the V2O3/C nanosheets.
Synthesis of VO 2
V2O5 (1.2 g) and H2C2O4⋅2H2O (2.5 g) were initially added into deionized water (40 mL), then the above mixture was reacted at 75 °C under magnetic stirring for 60 min to obtain a dark blue dispersion. Then, the above dispersion was transferred into a 50 mL teflon-lined autoclave and kept at 180 °C for 180 min. Finally, the merchandise was collected and washed with ethanol and deionized water.
Preparation of Anti-Proton Electrolyte
A certain amount of Zn(OTf)2 (> 98%, TCI) was dissolved in deionized water to organize 3 M Zn(OTf)2 electrolyte (denoted as 0PEG electrolyte). Correspondingly, a specific amount of Zn(OTf)2 was dissolved in the co-solvent of 50 wt% PEG 400 and 50 wt% deionized water to obtain the anti-proton electrolyte (denoted as 50PEG electrolyte).