6LR61 battery.Organic flow energy storage battery achieves breakthrough in energy density

　　Recently, the Beijing Low-Carbon Clean Energy Research Institute and the Department of Chemical Engineering of Tsinghua University collaborated to develop an all-liquid organic flow energy storage battery. This research result has achieved a breakthrough in improving the energy density of organic liquid flow energy storage batteries. Its advantages of high energy density and high reactivity make it have broad application prospects in the field of large-scale energy storage. The research results were published in ACSApplied Energy Materials, an academic journal of the American Chemical Society, on February 11, and featured on the cover of the magazine.

　　In recent years, with the widespread application of energy storage systems, energy storage battery technology has also developed accordingly. The reporter learned that battery systems that can achieve large-scale energy storage are showing a diversified trend. Common energy storage systems include lithium batteries and solid-state batteries. With all-vanadium flow batteries, etc. Among them, flow batteries stand out from the competition with traditional lithium batteries due to their higher safety. The electrolyte of the flow battery is in continuous circulation during operation, so it will not accumulate heat locally in the battery and cause overheating, and the safety has been greatly improved. However, flow batteries that use aqueous solution as the electrolyte face the problem of low energy density. The volume of their energy storage systems is often large, and their practical applications are accordingly limited. In this context, organic flow batteries overcome these two problems.

　　According to reports, the open circuit voltage of this flow battery is significantly higher than that of traditional flow batteries. At the same time, the theoretical energy density of this flow battery reaches 223 Wh/L, which is more than four times the theoretical energy density of traditional flow batteries (50 Wh/L). Experiments have shown that the active materials at the two poles of the active flow battery have excellent electrochemical properties and good cycle stability, with the current efficiency reaching 95% and the energy efficiency reaching 70%. Xing Xueqi, the first author of the paper and a postdoctoral fellow at the New Energy Research and Technology Center of the Beijing Low-Carbon Clean Energy Research Institute, said that the positive and negative raw materials of this flow battery are all organic compounds, which not only gets rid of the problem of low metal element reserves in the traditional electrolyte The preparation process is relatively simple and can achieve large-scale production. “The open circuit voltage and energy density of this organic flow battery are significantly higher than the traditional all-vanadium system, and it can store more energy in a limited space. In addition to being used in traditional stationary energy storage, it is expected to be used in mobile applications in the future. energy storage and electric vehicles." Xing Xueqi said.

　　It is worth mentioning that the separator, electrodes and electrolyte of this organic flow battery can be recycled, and there is no problem of heavy metal pollution after the traditional electrolyte is scrapped. Xing Xueqi said: “The organic solvent in the electrolyte of the organic flow battery can be separated by vacuum distillation first, and then reused after purification. The remaining electrolyte can be further subjected to solid-liquid separation operation to combine the solid supporting electrolyte and the liquid active component. Separate it and then go through a purification process so it can be reused.”

　　According to Dr. Liu Qinghua, the person in charge of the project, after three years of hard work, the high-power density all-vanadium redox flow battery led by the Low Carbon Institute has completed laboratory small-scale development and preliminary pilot testing, and is preparing for further pilot testing and technology Demonstration work, the main application scenarios include user-side energy storage, off-grid power supply, peak shaving and valley filling, etc. Specific projects will be launched in 2020.

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