Highly stable titanium–manganese single flow batteries for stationary energy storage

Abstract

Manganese-based flow batteries have attracted increasing interest due to their advantage of low cost and high energy density. However, the sediment (MnO2) from Mn3+ disproportionation reaction creates the risk to...

Electrolyte Regulation of Bismuth Ions toward High-Performance Aqueous Manganese-based Batteries

“…As the current density increases, the EE and VE of the full cell decrease. However, at a current density of 20 mA cm –2 , the VE and EE are as high as 94.2 and 91.4%, respectively, which are highly comparable to those of the redox flow batteries (Figure d). ,− Impressively, it is shown that the CEs of the full cell are >99% at all rates (Figure e). In addition, to show the practical applications of the aqueous static MnO 2 –Cr (Bi) batteries, we demonstrated our device to be able to power an LED digital screen with a symbol of “USTC” (Figure f).…”

“…The excessive demands of renewable energy sources have urged the development of advanced electrochemical energy storage (EES) systems, − which are considered to be the most promising energy storage technologies for large-scale applications. − However, the existing EES technologies, as represented by lithium-ion batteries, have been hindered by their safety concerns in recent years due to the utilization of flammable, volatile, and toxic organic electrolytes. − Therefore, much effort has been dedicated to the exploration of aqueous rechargeable batteries. − Among them, aqueous MnO 2 -based batteries (AMBs) are excellent alternatives, especially in large-scale energy storage applications, ,, owing to their high rate, environmental benignity, fabrication easiness, long cycle life, and high safety. − …”

“…An effective strategy we propose here is to utilize liquid-state reactive anodes in developing novel MnO 2 -based batteries to promote their electrochemical performance. The liquid reactions are widely used in redox flow batteries, such as V 3+ /V 2+ , Ti 3+ /TiO 2+ , and Cr 3+ /Cr 2+ . The Cr 3+ /Cr 2+ reactions were initially developed for Fe–Cr redox flow batteries. , They have several advantages such as a suitable potential (−0.41 V vs SHE), low cost, high specific capacity (515.5 mAh g –1 ), and fast reaction kinetics. ,, Some previous attempts have been made to improve the electrochemical performance of the Cr 3+ /Cr 2+ redox couple. ,− In the 1980s, Yeager et al grew solid bismuth hydride as an electrode, which suppressed the HER side reaction and enhanced the reversibility and reaction kinetics of the Cr 3+ /Cr 2+ redox couple .…”

“…CV curves of the cathode and anode obtained at a scan rate of 1 mV s –1 show behaviors of quasi-reversible redox reactions (Figure d,e). The redox peak currents (oxidation: anodic peak current of i pa ; reduction: cathodic peak current of i pc ) in the CV curves can be used to evaluate the kinetics and reversibility of electrochemical reactions. ,− In the pristine electrolyte, the i pa of the cathode MnO 2 /Mn 2+ redox couple is 6.78 mA cm –2 , and the i pc is 4.43 mA cm –2 (Figure d), which are 19.21 and 7.58 mA cm –2 for the anode Cr 3+ /Cr 2+ redox couple (Figure e), respectively. When the electrolyte regulation strategy is applied, the redox peak currents are greatly enhanced for both the cathode and the anode.…”

“…An effective strategy we propose here is to utilize liquid-state reactive anodes in developing novel MnO 2 -based batteries to promote their electrochemical performance. The liquid reactions are widely used in redox flow batteries, such as V 3+ /V 2+ , 36 Ti 3+ /TiO 2+ , 18 and Cr 3+ /Cr 2+ . 37 The Cr 3+ /Cr 2+ reactions were initially developed for Fe−Cr redox flow batteries.…”