New direction for long-term energy storage: Vanadium flow battery

New direction for long-term energy storage: Vanadium flow battery

The vanadium flow battery is a redox battery with vanadium as the medium. Its full name is Vanadium Redox Flow Battery (VFB), which was proposed  by Marria Kacos of the University of New South Wales, Australia in 1985. The vanadium battery energy storage system has high energy storage efficiency and can be widely used in power plant power storage. It can store excess electricity under low load and input electricity into the grid as an auxiliary power source under high load, reducing energy waste.

Vanadium batteries can store energy for a long time. When an emergency occurs, the stored electrolyte can be immediately put into use, which is much faster than emergency power generation devices. It can be used as an emergency power supply after a power outage. Since intermittent energy sources such as wind and photovoltaics have poor power generation stability, voltage fluctuations and flickers, and cannot form a stable power supply, a high-efficiency, low-cost energy storage system is needed to cooperate with it. Vanadium batteries just meet this requirement, and have adjustable storage energy, easy to monitor capacity and charge state, and flexible adjustment of charge and discharge power according to needs.

Vanadium batteries have a low self-discharge rate and high specific energy, and can be used to build large-scale vanadium battery power stations, greatly reducing the demand for long-distance transmission equipment installation. They have very superior economic efficiency and reduce the safety hazards brought about by a large number of high-voltage transmission equipment.

Vanadium flow battery has the following advantages:
Configuration flexibility. The vanadium battery has a flexible design. The output power of the battery is determined by the size of the battery stack. Increasing the number of single cells and the effective area can increase the battery stack power. The capacity of the battery is determined by the amount of electrolyte. Increasing the volume and concentration of the electrolyte can increase the battery capacity. The power and capacity can be adjusted according to the load size of various application sites and fields. For large-scale new energy power plants, increasing the energy storage capacity can reduce the levelized cost per kilowatt-hour.

Long battery life. The vanadium battery has a cycle number of more than 13,000 times and a service life of more than 20 years. Deep charging and deep discharging of the system will not affect the battery performance, and the system discharge depth (DOD) is ≥90%. Charging and discharging at fast and high current density will not damage the battery.

High safety. Vanadium batteries are water-based systems that require almost no thermal management, are free of explosion and fire hazards, and are equipped with leak-proof devices to prevent electrolyte leakage.

Environmentally friendly. The positive and negative electrolytes of vanadium batteries do not directly contact each other, can be recycled indefinitely, and will not pollute the environment. The electrodes in the battery stack materials are made of carbon/graphite felt, and the bipolar plates are mostly made of graphite or carbon materials, which will not pollute the environment after being scrapped. Other materials are mostly polymer materials and can be recycled.

Low life cycle cost. Vanadium batteries require a large initial investment, and material costs account for a large proportion, so the unit investment cost is higher than that of lithium batteries, but they have the advantage of durability. From the perspective of life cycle costs, the construction cost of vanadium flow batteries is much lower than that of lead-acid batteries and lithium-ion batteries.