posted on 2020-07-02, 14:15authored byZhuoyu Li, Jingyu Xi, Le Liu, Zenghua Wu, Dongzhi Li
Capacity decay during the long-time
cycles is one of the drawbacks
of an all-vanadium redox flow battery which limits its application
in the large-scale energy storage. Based on the convenient and effective
reflow method, we add online electrolysis to restore the capacity
by reducing the accumulated VO2+ (pentavalence)
in the positive electrolyte during long-time charge and discharge
cycles. In this work, the capacity restore effects of online electrolysis
with three reflow volumes are tested; the mechanism of the special
discharge capacity retention behavior is discussed, and the benefits
and limitations of the capacity recovery method are explored. In this
work, the capacity is restored apparently, and the all-vanadium redox
flow battery runs 4680 cycles stably through eight online electrolysis
processes, which is owing to the controlled volume imbalance by the
reflow and the compensated valence imbalance by the online electrolysis.
Although the concentration imbalance accumulated during the long-time
cycles limits the capacity recovery which needs to be addressed by
combining with mixing the positive and negative electrolytes in the
future, considering the convenience and the low cost of this method,
it has promising application in large-scale energy storage. Hence,
this method is free from replacing electrolyte, lowers the maintenance
cost, and improves the competitiveness and further popularization
of the all-vanadium redox flow battery as a smart grid energy storage
module.