Vanadium redox flow battery with slotted porous electrodes and automatic rebalancing demonstrated on a 1 kW system level

An optimal electrolyte addition strategy for improving performance of a vanadium redox flow battery

“…More and more demands for renewable energy bring about extensive attention to the large‐scale energy storage systems . Among them, all vanadium redox flow battery (VRFB) shows superiority by reason of its long cycling life, deep discharge, high‐energy efficiency, and mutual independence of power and energy ratings . In spite of the aforementioned advantages, the important issues with respect to discharge capacity of the battery, output power, and the efficiencies are still existing.…”

“…Besides, properties of the electrolyte and the membrane are also improved by the researchers . For the given assembly materials and electrolyte, performance of the battery can be enhanced by optimizing its structures as well as the operating conditions that play an important role in the species transport of the VRFBs …”

“…Another study also discovered that capacity decay of the battery can be alleviated by asymmetric current strategy by reason of enlarged electro‐osmotic convection to negative side, which suffers from the detrimental effect of decreased voltage efficiency at the same time. Additionally, Bhattarai et al maintained the discharge capacity decay of a 20‐cell, 1‐kW vanadium redox flow battery stack by utilizing hydraulic shunt between two electrolyte tanks. Similarly, Wang et al adopted an electrolyte‐reflow method and retarded the capacity decay of the battery.…”

“…14 Besides, properties of the electrolyte and the membrane are also improved by the researchers. [15][16][17] For the given assembly materials and electrolyte, performance of the battery can be enhanced by optimizing its structures as well as the operating conditions 5,6,[18][19][20][21][22][23][24][25] that play an important role in the species transport of the VRFBs. 26 In the VRFB, one disadvantageous characteristic is the vanadium transport across the membrane, ie, vanadium crossover.…”

“…For the sake of mitigating the electrolyte imbalance and SOC imbalance between two half-cells as well as the associated capacity decay of the VRFB, many researchers have put forward various battery structures and operating strategies. 4,6,18,24,32,[38][39][40][41][42][43][44] Lu et al 18 investigated asymmetric electrode compression structure with a 2-D, transient mathematical model with concluding diffusion, convection, and migration mechanisms across the membrane as well as the electrode compression effects. Results show that discharge capacity decay of the battery can be reduced due to appropriate adjustment of convective flux of vanadium ions across the Nafion membrane.…”