Flow battery is an electrochemical battery, in which both positive and negative active materials are liquid. The liquid active substance is both an electrode active substance and an electrolyte solution, which is stored in a separate liquid storage tank, and the electrolyte solution flows into the battery pack through an external pipeline and a fluid pump for reaction.
Under the action of mechanical power, liquid active substances circulate in the closed loop of different liquid storage tanks and the battery stack, and the ion exchange membrane acts as the diaphragm of the battery stack, and the electrolyte flows across the electrode surface in parallel, resulting in electrochemical reaction. The system collects and conducts current through bipolar plates, thus converting the chemical energy stored in the solution into electrical energy. This reversible reaction process enables the flow battery to successfully complete charging, discharging and recharging.
Compared with other electrochemical cells, iron-chromium flow battery has obvious technical advantages, and the specific advantages are as follows.
(1) has many cycles and long service life. The minimum cycle life of Fe-Cr flow battery can reach 10000 times, which is the same as that of all-vanadium flow battery and is much longer than that of sodium-sulfur battery, lithium-ion battery and lead-acid battery.
(2) No explosion and high safety. The electrolyte of Fe-Cr flow battery adopts aqueous solution, so there is no explosion danger. Electrolyte is stored in two independent liquid storage tanks, and the battery stack is separated from the liquid storage tanks, and the battery stack operates at normal temperature and pressure, with high safety.
(3) The electrolyte solution has low toxicity and corrosiveness and good stability. The electrolyte of iron-chromium flow battery is a dilute hydrochloric acid solution of iron salt and chromium salt, which has low toxicity and corrosiveness.
(4) Strong environmental adaptability and wide working temperature range. Compared with other flow batteries, the working temperature of Fe-Cr flow battery is wider, and the electrolyte can be started in the full range of -20 ~ 70℃.
(5) The storage tank is designed without automatic discharge. The electric energy is stored in the electrolyte, and the electrolyte is stored in the storage tank, so there is no self-discharge phenomenon, which is especially suitable for standby power supply.
(6) Customized design, easy to expand. The rated power and rated capacity of Fe-Cr flow battery are independent, the power depends on the battery stack and the capacity depends on the electrolyte, and the power and capacity can be customized according to the user's needs. Under the condition of constant power demand, it is very simple to add electrolyte solution to expand capacity.
(7) Modular design, high system stability and reliability. The iron-chromium flow battery system adopts modular design. Take a 250 kW module as an example. A module consists of eight battery stacks and is placed in a standard container, so the consistency between battery stacks is good, the system control is simple, and the performance is stable and reliable.