Vanadium flow battery: The vanadium flow battery (VRB, also commonly referred to as vanadium battery) was proposed by Maria Kazacos from the University of New South Wales in Australia in 1985. As an electrochemical system, vanadium batteries store energy in electrolytes containing redox pairs of vanadium ions in different valence states. Electrolytes with different redox pairs form the positive and negative electrolytes of the battery, which are separated by an ion exchange membrane. The solution is pumped from the storage tank into the battery stack through an external pump to complete the electrochemical reaction. After the reaction, the solution returns to the storage tank, and the active substance continuously circulates and flows, thus completing the charging and discharging process. Lithium ion flow battery: Lithium ion flow batteries are mainly composed of battery reactors, positive electrode suspension storage tanks, negative electrode suspension storage tanks, liquid pumps, and sealed pipelines. Among them, the positive electrode suspension storage tank holds a mixture of positive electrode active material particles, conductive agent, and electrolyte, while the negative electrode suspension storage tank holds a mixture of negative electrode active material particles, conductive agent, and electrolyte. The battery reactor is the core of lithium-ion flow batteries, and its structure mainly includes: positive electrode current collector, positive electrode reaction chamber, porous separator, negative electrode reaction chamber, negative electrode current collector, and outer shell. Lithium ion flow batteries use a liquid pump to circulate the suspension during operation. The suspension flows continuously or intermittently between the suspension storage tank and the battery reactor through a sealed pipeline driven by the liquid pump or other power sources. The flow rate can be adjusted according to the concentration of the suspension and the ambient temperature. Zinc bromide flow battery: Zinc bromine flow battery is a type of flow battery that belongs to energy storage and can be charged and discharged with high capacity for a long time. China has successfully developed the first zinc bromine flow energy storage system through independent innovation, realizing the independent production of key materials such as separators, plates, and electrolytes for zinc bromine batteries. Zinc cerium flow battery: The zinc cerium flow battery was proposed by Clarke in 2003, who claimed that the capacity of the energy storage system could reach 250000 kW ▪ Above h, the open circuit voltage is 3.33 V. The zinc cerium flow battery uses Ce3+/Ce4+as the positive electrode active pair and ZnO/Zn2+as the negative electrode active pair. The positive and negative electrolytes are stored in two different storage tanks. Zinc nickel flow battery: In 2007, Cheng Jie et al. proposed the zinc nickel single flow battery. High concentration zincate is dissolved in concentrated alkali as a supporting electrolyte. During charging, zinc in the zincate is reduced and electrodeposited on the negative electrode, while Ni (OH) 2 is oxidized to NiOOH on the positive electrode. During discharge, the opposite reaction occurs. Lead flow battery: To avoid the many drawbacks of dual flow batteries, Professor Pletcher and his research team from the UK proposed a fully deposited single flow battery system in 2004 based on a deep understanding of traditional lead-acid batteries, and conducted a series of in-depth studies on this single flow battery system. This battery system uses an acidic lead (I) methylsulfonate solution as the electrolyte, and inert conductive materials (carbon materials) are used as the electrode substrate for both the positive and negative electrodes. During charging, Pb2+in the electrolyte undergoes a reduction reaction at the negative electrode to form metallic Pb, which deposits on the negative electrode substrate; At the same time, Pb2+undergoes oxidation reaction at the positive electrode to generate PbO2 and deposits on the positive electrode substrate. Due to the fact that the active substances Pb and PbO2 generated by electrodeposition are insoluble in methylsulfonic acid solution within a certain temperature range, there is no problem of contact between positive and negative active substances in this flow battery system. Therefore, there is no need to use ion exchange membranes, and even the permeable membrane in a single deposition flow battery is not required. Therefore, there is no problem of using two sets of electrolyte circulation systems. All of these greatly reduce the cost of flow batteries, making all lead flow batteries have a very bright application prospect in the field of energy storage batteries. Iron chromium flow battery: The earliest concept of liquid flow energy storage battery was first proposed by Thaller in 1974. It utilizes the reducibility of Cr2+in Cr3+/Cr2+and the oxidizability of Fe3+in Fe3+/Fe2+to perform electrochemical redox reactions in acidic Cr3+and acidic Fe2+electrolytes separated by proton exchange membranes. The flow battery uses Fe2+/Fe3+pairs as the positive electrode electrochemical reaction pairs during the charging and discharging process, and Cr3+/Cr2+pairs as the negative electrode electrochemical reaction pairs during the charging and discharging process. During the charging and discharging process, the constant current pump pushes the electrolyte to circulate in the closed loop formed between the positive and negative electrode half cells and their corresponding electrolyte storage tanks. Sodium polysulfide/bromine flow battery: The Sodium Polysulfide/Bromide Redox Flow Battery (PSB) was first proposed by Remick and Ang from Georgia Institute of Technology in the United States in 1984. But it was not until the early 1990s that Regenesys began to focus on researching and developing practical sodium polysulfide/bromine flow batteries. And have successively developed three kilowatt level battery packs, one, ten, and one hundred. The flow battery system is composed of NaBr and Na2S2 as positive and negative electrolytes, and a sodium ion exchange membrane as a separator. The open circuit voltage of this flow battery is around 1.74V, and its energy density can reach 20-30W ▪ H ▪ L. During the charging process of sodium polysulfide/bromine flow batteries, Br - in the positive electrode electrolyte undergoes oxidation reaction on the surface of the positive electrode to generate Br2 elemental substance. At the same time, S element in the active material sodium polysulfide in the negative electrode is reduced. Throughout the electrochemical reaction process, Na+in the positive electrode electrolyte migrates to the negative electrode through the sodium ion exchange membrane; During the discharge process of a flow battery, an electrochemical reaction occurs that is opposite to the charging process. At the same time, Na+in the negative electrolyte migrates to the positive electrode through the sodium ion exchange membrane. Zinc iron flow battery: Zinc iron flow batteries have become one of the hot technologies in electrochemical energy storage due to their advantages of safety, stability, and low electrolyte cost. The electrolyte of zinc iron flow batteries can operate within a wide pH range. Therefore, based on the different acidity and alkalinity of the electrolyte, zinc iron flow batteries can be divided into three categories: alkaline, acidic, and neutral zinc iron flow batteries.