Is it normal that the energy efficiency of flow battery is about 40%?

Not normal. The energy efficiency of flow battery is abnormal about 40%. According to the summary of experts' exchange on flow battery-all vanadium iron chromium zinc bromide battery, the efficiency of vanadium flow battery is 70%. Manufacturers advertise that they can achieve 72-73%, but in fact they can only achieve 65-70%. In terms of energy density, the energy density of flow battery is relatively low because of the limitation of electrolyte composition. For a large-scale energy storage project of 100 MW /400 MWh flow battery, if the same site is replaced by lithium battery, it can reach 800- 1000 MWh. At present, there are few companies doing zinc-bromine liquid flow in China. Anhui Meineng Company has promoted it for some time before, but in recent years, due to various reasons, the promotion is no longer so active, and now there are fewer demonstration projects in China.