Liquid flow battery, born for energy storage! "Specially designed for aviation", safety attributes in its blood

In the energy storage arena, flow batteries are both new and old. Compared with lithium batteries, flow batteries have an earlier origin and more mature technology. What is new is that they have only become known to the public in the past two years.

In 1884, French engineer Charles Renard invented the zinc-chloride liquid battery for use in military airships. It had already taken shape as the prototype of the zinc-bromine liquid flow battery, but there was no additional fluid drive system at that time.

In 1950, ion exchange membrane was born and liquid flow battery technology began to take shape.

In 1955, General Electric Company sulfonated polystyrene to produce the first proton exchange membrane. Just like chips in the electronics industry, liquid flow batteries have made new breakthroughs.

In 1971, Japanese scientists Ashimura and Miyake first proposed the concept of liquid flow battery in the modern sense. By dissolving the positive and negative active materials in the electrolyte, a reversible redox reaction occurs on the inert electrodes to achieve the mutual conversion of electrical energy and chemical energy.

Since 1973, NASA has been studying flow batteries for solar energy storage systems at lunar bases, with safety, efficiency and life of the battery being the primary considerations, while cost is a secondary factor. A year later, NASA scientist LH Thaller first proposed a detailed model of a flow battery with practical significance, using FeCl ₂ and CrCl ₃ as positive and negative active materials and stored in two external tanks, hydrochloric acid as the matrix, anion exchange membrane as the diaphragm, and a circulation pump as the flow driving force, forming the first Fe-Cr dual flow battery.

The birth of liquid flow battery technology was originally intended to be a long-term space flight energy replacement plan against the backdrop of the energy crisis in the 1970s. In other words, liquid flow batteries were born for energy storage, especially long-term energy storage. If it weren't for the suspension of the moon landing plan at the time and the easing of global oil prices, perhaps the current liquid flow battery applications would be labeled "aviation-specific". In recent years, with the rapid increase in installed capacity of new energy power generation such as wind power and photovoltaics, and the continuous introduction of new national energy storage policies, energy storage has become the hottest trend. As the most promising seed player in new energy storage and long-term energy storage, flow batteries have made breakthrough progress in 2022, and may shake up the market structure dominated by lithium batteries in the future.

The CFE 2024 China Liquid Flow Battery Energy Storage Conference and Exhibition, jointly initiated by the Global Liquid Flow Battery Network, China New Energy Network (Energy Pass), and the Global Energy Storage Network, together with relevant industry chain enterprises and scientific research groups, is scheduled to be held in Hangzhou on April 25-26. This time, we strive to bring together industry-university-research experts, scholars, and enterprises from the top circles of the liquid flow battery industry chain to build a complete upstream and downstream industry chain and network business circle, helping friends who are interested in energy, electricity, energy storage, power grids, industry and commerce, venture capital institutions, investors, etc. to have a personal, rapid and all-round in-depth understanding of this industry. I hope that here everyone can discuss technology, interpret policies, formulate industry standards, analyze the market, explore business models, business cooperation, friendly exchanges, answer questions and solve doubts, and work together to promote the scale, industrialization and commercial development of the liquid storage industry!

What is a flow battery?

Liquid flow battery is a kind of electrochemical energy storage, which is mainly composed of electrodes, ion-conducting membranes and electrolytes. Substances with electrochemical reaction activity are stored in a flowable liquid electrolyte, which flows through the electrodes to undergo a reversible redox reaction and then returns to the storage tank for storage. This repetitive circulation of electrolyte is the specific meaning of "liquid flow".

Among the basic components of a flow battery:

(1) The electrode provides a place for the electrochemical reaction, but does not participate in the reaction itself. The charging can reach 100% SOC. The battery power can also be regulated by adjusting the number of battery stacks or the electrode area.

(2) The active substances participating in the reaction are dissolved in the electrolyte and stored in the storage tank. The battery capacity can be regulated by adjusting the electrolyte parameters and the capacity of the storage tank. This also means that the capacity and power of the flow battery can be designed separately.

(3) Aqueous electrolytes in which active substances are dissolved in water have no risk of explosion or fire, thus ensuring the safety of the battery.

It can be seen that the characteristics of flow batteries determine their advantages such as safety, separate design of power and capacity, and large energy storage scale, making them "tailor-made" for large-scale energy storage.

Liquid flow batteries are regarded as one of the most suitable battery technologies for long-term energy storage. The most suitable solutions can be tailored for different energy storage needs. Its unique working principle and structure give it many advantages in the field of energy storage. Under the guidance of the dual carbon goals, my country's energy structure is continuously being optimized, which provides broad application prospects for the development of liquid flow batteries. With the development of new energy and energy storage, liquid flow batteries will play an increasingly important role in the future energy storage market, provide strong support for my country's sustainable development, and promote the transformation of my country's energy structure and the development of new energy.

——Liquid flow battery, born for energy storage! China New Energy Network/Global Liquid Flow Battery Network Zhou Zhou

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