Recently, the 21st China Science and Technology Forum was held in Chongqing. The theme of the forum focused on the technology of chemical energy storage materials. Shen Aimin, head of the academic department of the Chinese Association of Science and Technology, and Wu Gang, vice mayor of Chongqing, attended the meeting and delivered speeches. How can energy storage materials break through the current technical bottleneck? Which new materials are most promising? How to ensure the safety of energy storage batteries?
Current energy storage technology is relatively backward
Moderator: What is the application prospect of energy storage batteries? Why does it say it will change the pattern of resource use in the future?
Zhang Huamin: Energy storage batteries are widely used, including lithium batteries for mobile phones and cameras in daily life, as well as large energy storage batteries for storing wind energy and solar energy. The current technologies used for large-scale energy storage mainly include pumped energy storage, compressed air energy storage, flow batteries, sodium-sulfur batteries, and lead-acid batteries. Relatively speaking, energy storage batteries are more convenient to use, benefiting from the materials industry The rapid development of the energy storage battery has a bright future.
The reason is, on the one hand, due to resource shortages and environmental problems. With the development of the country's science and technology and society, and the improvement of people's living standards, energy and environmental issues are receiving more and more attention. The contradiction between supply and demand in energy is becoming more and more obvious. Renewable resources such as ocean energy, however, renewable energy such as wind energy, solar energy and ocean energy are greatly affected by weather and time period, have obvious instability, discontinuity and uncontrollable characteristics, and need to develop and construct supporting electrical energy storage ( Energy storage) device to ensure the continuity and stability of power generation and power supply, and the large-scale energy storage technology used in the power industry for "peak clipping and valley filling" of power, will greatly improve the contradiction between power supply and demand, and increase power generation Equipment utilization.
On the other hand, it is the future development trend. The development bottlenecks of new energy, smart grid and electric vehicles in the three major emerging industries in the future all point to the same technology: energy storage materials (energy storage battery) technology. The current development of energy storage technology is relatively backward. Many countries have positioned large-scale energy storage technology as a strategic technology to support the development of new energy. At present, the technology development of energy storage materials in the world is very rapid. Whether in the level of energy storage material technology development or in the transformation of achievements into an advantageous industry level, China has a lot of pioneering work to be carried out urgently.
A battery unified? Not too possible
Moderator: There are many types of energy storage batteries, and their respective advantages and disadvantages are more obvious. So is it possible to have a "perfect energy storage battery" to adapt to energy storage under various conditions?
Wen Zhaoyin: At present, energy storage batteries are unlikely to have a battery to "unify the rivers and mountains". Different materials of batteries have their own characteristics to adapt to different conditions. For example, nickel-zinc batteries and lithium batteries are suitable for small devices such as mobile phones; Sodium-sulfur batteries and all-vanadium flow batteries are suitable for large energy storage equipment. The future development of batteries for energy storage batteries may be a situation of blooming flowers. What is certain is that advances in energy storage technology will profoundly change our lives.
The impact of energy storage batteries on people's lives will be within reach. Problems such as the daily charging of mobile phone batteries, insufficient tablet power, and limited battery life of laptop computers will be solved through technological innovation. Research on high specific energy materials has become a key issue for the advancement of energy storage batteries.
Wu Feng: Electric vehicles have entered our vision more and more. It will be an important way to solve the oil energy crisis and achieve clean energy. Domestic BYD, Changan, Chery and other automobile companies have already launched pure electric vehicles. The key lies in the development of power batteries with high energy density, low cost and high reliability. Energy storage batteries suitable for electric vehicles require large power and large capacity, but currently domestic batteries have high prices, heavy batteries, insufficient single charge mileage, and the need for a large amount of land to build charging stations and power exchange stations. This also greatly restricts The promotion of electric vehicles has also lowered the consumer's propensity to buy. In Beijing, to buy fuel-powered vehicles, the license plate needs to be marked; if you buy a pure electric vehicle, you do not need to dial. Even so, few people buy electric cars.
From another perspective, we cannot blindly advance. Low technology maturity and little demonstration application experience are common problems in domestic energy storage technologies. Energy storage batteries need revolution in high performance, high safety, and high cost performance, and there is still a period of commercialization. Although in the field of energy storage batteries, China is at an advanced level in the world,
In the process of large-scale industrialization, it is necessary to gradually and progressively promote the effect of direct promotion of electric vehicles. We need such a smooth transition, such as the development of hybrid electric vehicles first, and accumulate more experience in practice. During this period, technology will continue to progress, and for problems that cannot be solved now, it is possible to get a better solution.
Safety is more important for large-scale grid energy storage
Moderator: In 2011, Zotye â€™s electric vehicle â€œspontaneously ignitedâ€ in Hangzhou; a pure electric bus in Shanghai also experienced â€œspontaneous combustionâ€; in June this year, a traffic accident occurred in Shenzhen â€™s Binhe Avenue, and a BYD e6 pure electric taxi Fired after being rear-ended. The safety of electric vehicles is tortured, so how to ensure the safety of energy storage batteries?
Wu Feng: We say that high energy and high power mean potential chemical instability. Since the problem of battery safety is not a single factor, it should be based on a thorough understanding of the battery reaction mechanism and its associated side reactions in the application environment. The angle and system improve the safety and reliability of lithium-ion batteries. As far as the battery itself is concerned, there is room for improvement in the positive electrode materials, negative electrode materials, and electrolytes that make up the battery.
Lai Xiaokang: For large-scale energy storage in the power grid, I think safety is more important, because its scale is relatively large, and when it reaches megawatts or dozens of megawatts, small-capacity laptops are easy to burn, so bigger In the future, if there is a problem, the impact will be greater. The performance of the energy storage device itself has to be greatly improved, especially for its cost performance and safety, and high safety is what we must guarantee.
Liang Guangchuan: The electrolyte is a relatively big problem. Lithium ion electrolytes are organic, and the tips are all mercury. To develop new electrolyte systems with good thermal stability, flame retardant or even non-combustible, we also need to pay attention to the matching of electrodes and electrolyte materials; to study new electrolyte systems with wide electrochemical windows, we need to develop new electrolyte systems with high decomposition voltage. The electrolyte is more commonly used in organic solutions of hexafluorophosphoric acid. We believe that replacing the electrolyte with ionic liquid may be a viable method, and it has been applied on a large scale. Room temperature ionic liquids are non-volatile, non-flammable, high Conductive, high-voltage windows, combined to form a replacement for this liquid electrolyte, have a relatively large improvement in terms of safety performance, which is a direction of effort.
Zhang Huamin: Finding new materials is the key to the development of energy storage batteries. All vanadium flow energy storage battery is one of the directions, but this battery also has its advantages and weaknesses. The all-vanadium flow battery can achieve a scale of dozens of megawatts and dozens of megawatts. According to our experiments, it can cycle more than 13,000 times. Another point is different from the lithium battery. The state of the lithium battery is difficult to detect, but the flow battery can know how much electricity can be discharged and how much electricity has been discharged according to the curve; it is also environmentally friendly, and the electrolyte can be used permanently. Some people say that vanadium It is toxic, but it is less toxic after being made into a liquid. Its biggest feature is its better safety, which will not cause fire or explosion. There is a weak point where the energy is relatively low, about 20 watt-hours per kilogram, and its stability and reliability need to be improved.
Guo Jingbin: We are now working on another subject, which is the safety early warning system for electric vehicles. That is to say, the burning of the battery cannot be prevented now, but it can be known in advance through a large amount of data whether this battery has potential safety hazards, and the extent of the potential hazards, so that the passengers can be alerted in advance. This system is able to know in advance whether the battery has potential safety hazards through a large amount of data analysis, whether or not to stop and let the guests leave. This thing can't be done by our company, because the collection of large amounts of data including modeling requires the help of peers and even the support of the government.
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