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All-vanadium redox flow batteries has received great attention as a possible solution for the large-scale energy storage system (ESS), which is first invented by M. Skyllas Kazacos in 1985. This system has several advantages such as a long cycle life, design flexibility, and safety etc., however, the low energy density, and poor reactivity on carbon materials are a great obstacle in market penetration. We used the corn protein, "zein" as a nitrogen doping source, which has been produced by the Unites States as a leading producer for a long period, left behind as a byproduct after the manufacture of corn flour, corn oil, and bio-ethanol and so forth. This study presents that the highly effective corn protein-derived nitrogen-doped carbon materials with oxygen-rich electrocatalyst can be achieved by the safe and low-cost method. Thus, this technology with cost-effective and scalable properties are greatly important for its application in grid-scale energy storage systems. In addition, the application of corn protein as the heteroatom doping sources will be readily adaptable for other electrode materials applied to various battery systems.Recent studies for all-vanadium redox flow batteries (VRFBs) have been focused on carbon-based materials for cost-effective electrocatalysts to commercialize them in grid-scale energy storage markets. We report an environmentally friendly and safe method for carbon-based catalysts by a corn protein self-assembly. This new method allows the carbon black nanoparticles to be coated with nitrogen-doped graphitic layers with oxygen-rich functionalities (N-CB). We observed the increased catalytic activity of this catalyst toward both V 2+ /V 3+ and VO 2+ /VO2 + ions, showing the 24 % increased mass transfer process and ca. 50 mV higher reduction onset potential comparing to CB catalyst. It is believed that the abundant oxygen active sites and nitrogen defects of the N-CB catalyst are beneficial to the vanadium redox reaction by improving electron transfer rate and faster vanadium ion transfer kinetics.Corn protein-derived nitrogen-doped carbon nanomaterial was fabricated, which has abundant oxygen active sites and nitrogen defects for vanadium redox reactions.(6.75 cm X 4 cm)

Oxygen functional groups play a key role in vanadium redox reactions. To identify the effective location of oxygen functionalities in graphene‐based nanomaterials, a selectively edge‐functionalized graphene nanoplatelet (E‐GnP) with a crystalline basal plane is produced by a ball‐milling process in the presence of dry ice. For comparison, the reduced graphene oxide (rGO) that contains defects at both edges and in the basal plane is produced by a modified Hummers' method. The location of defects in the graphene‐based nanomaterials significantly affects the electrocatalytic activity towards vanadium redox couples (V2+/V3+ and VO2+/VO2 +). The improved activity of these nanoplatelets lies in the presence of oxygen defects at the edge sites and higher crystallinity of basal planes than in rGO. This effective location of oxygen defects facilitates fast electron‐transfer and mass‐transport processes.

hybrid RFBs electrodeposit at least one active species, e.g., lithium, aluminum, or zinc, onto nonflowing electrodes. The metal deposition process usually occurs on the negative electrode side. Although many hybrid RFBs utilize nonaqueous electrolytes to attain high working potential, a zinc-based hybrid system can attain a relatively high working potential in a nonflammable, lower-cost aqueous electrolyte. This is because the zinc/zincate redox couple, Zn/[Zn(OH) 4 ] 2− , in a pH 14 alkaline solution has the advantage of a large negative redox potential of −1.23 V versus the standard hydrogen electrode (SHE). An example is the alkaline zincferricyanide hybrid RFB, which was first reported in the 1970s and is still under development. [3] However, the low solubility of the [Fe(CN) 6 ] 3− /[Fe(CN) 6 ] 4− couple at high pH limits the energy density and constrains practical implementation. [4] In addition, acidic zinc-bromine hybrid RFBs have been widely studied and are being commercialized; however, the toxicity and corrosivity of bromine limits widespread deployment. [1] Recently, redox-active organic and organometallic molecules have been widely studied for their promise of enabling the development of inexpensive flow batteries. [5][6][7] These molecules exhibit structural diversity and broad tunability, permitting the engineering of solubility, redox potential, kinetics, and stability. Many different types of molecules, including quinones, [8][9][10][11][12] phenazines, [13,14] viologens, [7,[15][16][17][18][19] alloxazines, [20] and (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, [13,15,16,21,22] have demonstrated good electrochemical performance as redox-active materials in aqueous organic redox flow batteries (AORFBs). Most of these molecules exhibit low reduction potentials and consequently have been explored as negolyte (negative electrolyte) materials. Some exceptions are tetrachloro-1,4 benzoquinone and 4,5-dihydroxybenzene-1,3-disulfonic acid, which have high positive reduction potentials of >0.8 V versus SHE in acidic solution. [9,11,23] Thus, by pairing high potential organic molecules such as these with the Zn/[Zn(OH) 4 ] 2− redox couple, a new type of hybrid RFB can be designed to achieve a high cell voltage.However, it is difficult to pair an alkaline electrolyte and an acidic electrolyte within conventional single-membrane RFBs due to H + or OH − crossover. Recently, ceramic membranes and bipolar polymer membranes have been introduced into singlemembrane pH-differential flow cells, but the high resistance of these membranes has severely limited the current density. [24,25] Water-soluble redox-active organic molecules have attracted extensive attention as electrical energy storage alternatives to redox-active metals that are low in abundance and high in cost. Here an aqueous zinc-organic hybrid redox flow battery (RFB) is reported with a positive electrolyte comprising a functionalized 1,4-hydroquinone bearing four (dimethylamino)methyl groups dissolved in sulfuric acid. By utilizing a three-electrolyte...

Aluminum–air batteries are considered as next‐generation batteries owing to their high energy density with the abundant reserves, low cost, and lightweight of aluminum. However, there are several hurdles to be overcome, such as the sluggish rate of the oxygen reduction reaction (ORR) at the air electrode, precipitation of aluminum hydroxides and oxides at the anode, and severe hydrogen evolution problems at the interface of the anode and the electrolyte. Here, recent advances in silver metal and metal–nitrogen–carbon‐based ORR electrocatalysts, aluminum anodes, electrolytes, and the requirements of future research directions are mainly summarized.