Two types of batteries have been removed from medium and large-scale electrochemical energy storage stations!

Why is it prohibited? In recent years, fires have occurred frequently at energy storage stations in South Korea. As the mainstream energy storage technology in South Korea, ternary lithium batteries are precisely the \"number one culprit\" behind accidents. Chen Yongchong told China Science News that currently, most large and medium-sized chemical energy storage power stations abroad use lithium iron phosphate batteries and ternary lithium batteries, while in China, lithium iron phosphate batteries are used almost exclusively. Regarding the explicit ban in our country on the use of ternary lithium batteries in this field, he explained that the thermal runaway temperature of ternary lithium batteries is around 200°C; at high temperatures, the chemical reactions within the battery intensify, and oxygen molecules are generated during these reactions, which in turn accelerates the combustion of flammable gases, and explosions may even occur in a very short time. Another technology that was “removed from the list” is sodium-sulfur batteries. On September 21, 2011, a fire broke out in a sodium-sulfur battery (manufactured by NGK of Japan) in Ibaraki Prefecture, Japan. The fire burned for two weeks before it could be extinguished. Since then, the development of sodium-sulfur batteries has also declined sharply. Lu Yaxiang, an associate researcher at the Institute of Physics, Chinese Academy of Sciences, told China Science News that the high-temperature sodium-sulfur battery was invented and unveiled by the Ford Company in the United States in 1968, and its commercialization was achieved by the NGK Company in Japan in 2003. However, sodium-sulfur batteries can only operate properly at high temperatures of around 300°C; if the ceramic tube breaks and causes a short circuit, it will lead to a violent exothermic reaction, capable of generating temperatures as high as 2000°C, posing significant safety risks. Globally, only Japan’s NGK company is currently producing this type of battery, resulting in a lack of an industrial supply chain and economies of scale.

It is worth noting that the policy also states that medium and large-scale electrochemical energy storage stations should not use power batteries that have been reused. When selecting recycled power batteries, consistency screening should be conducted, along with a safety assessment based on traceability data. It is worth noting that, according to Everbright Securities’ projections, by 2030, the recycling of ternary lithium batteries and lithium iron phosphate batteries will create a market worth hundreds of billions of yuan. Among them, the market potential for the recycling of ternary lithium batteries is expected to reach 60 billion yuan at an average price level ； The market potential for the secondary use and recycling of lithium iron phosphate batteries is estimated to exceed 48 billion yuan. Regarding the decision not to use recycled batteries, Chen Yongchong believes that the main issue is the safety hazards associated with used power batteries. Due to the large number of power battery manufacturers, as well as the differences in technical approaches and product specifications, it is difficult to disassemble, evaluate, and reassemble batteries for secondary use. Moreover, the quality of these batteries varies greatly, and their widespread use can easily lead to safety accidents. Xia Yonggao, chairman of Ningbo Weifu Technology Co., Ltd. and a researcher at the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, told China Science News that the key requirement for cascade utilization technology is to ensure the quality and safety of the end products. In theory, it is possible to determine the historical usage history of retired batteries through coding, but in practice, such data is very difficult to obtain. He also pointed out that retired batteries inherently carry uncertainties, making it difficult to accurately assess their safety after long-term use. “Some companies use recycled batteries as power sources for low-speed vehicles, which also poses certain safety risks. ”Xia Yonggao believes that in the future, recycled batteries can be used in the field of small-scale energy storage, where requirements regarding safety and lifespan are relatively low.

With the ban on ternary lithium batteries in medium and large-scale electrochemical energy storage stations, will China’s lithium-ion battery market experience turmoil? The White Paper on the Development Index of China’s Lithium Battery Industry states that China has been the world’s largest market for lithium batteries for five consecutive years. In 2021, the global market size for lithium-ion batteries reached 545 gigawatt-hours, with China accounting for approximately 324 gigawatt-hours of this volume, representing around 59.4% of the global market. Data released by the Ministry of Industry and Information Technology show that in 2021, of the total national production of 324 gigawatt-hours of lithium-ion batteries, 72 gigawatt-hours were used in consumer applications, 220 gigawatt-hours in power applications, and 32 gigawatt-hours in energy storage applications. The total output value of lithium batteries exceeded 600 billion yuan. In the field of energy storage, by the end of 2021, China’s energy storage market had an installed capacity of 43.44 gigawatts, ranking first in the world. The installed capacity of electrochemical energy storage is 5,117.1 megawatts, accounting for 11.8%. Among them, lithium-ion battery energy storage technology accounts for 91.0% of the installed capacity. Focusing further on power batteries, lithium iron phosphate batteries are showing even stronger growth momentum. According to data from the China New Energy Vehicle Power Battery Industry Innovation Alliance, in 2021 the total capacity of power batteries installed in domestic vehicles was 154.5 gigawatt-hours, of which 79.8 gigawatt-hours came from lithium iron phosphate batteries, accounting for 51.7% – a figure higher than that of lithium-ion batteries.

The development of ternary lithium batteries has been facilitated by subsidy policies. After the introduction of energy density requirements in these policies in 2017, ternary lithium batteries with higher energy densities became the preferred choice for automakers. However, in recent years, the disadvantages of ternary lithium batteries in terms of cycle life and cost have become increasingly apparent, and especially the occurrence of multiple safety incidents has led to heightened attention from the market regarding battery safety. The energy density of lithium iron phosphate has increased in recent years. Chen Yongchong believes that the increasing share of lithium iron phosphate batteries is the result of market choices; “it is not policies that drive the market, but rather policies reflect the trends in market development.” Although lithium iron phosphate batteries are safer, there have been some fire incidents in recent years. On April 16, 2021, an explosion occurred at an energy storage station in Fengtai District, Beijing; the incident resulted in the death of two firefighters, and the direct property damage caused by the fire amounted to 16.6081 million yuan. Half a year later, the Beijing Emergency Management Bureau officially released the investigation results, stating that the direct cause of the fire was an internal short circuit in the lithium iron phosphate batteries. Therefore, Chen Yongchong emphasized that even lithium iron phosphate batteries still require new technological breakthroughs in terms of high safety, low cost, and easy recyclability. Xia Yonggao believes that the prohibition of ternary lithium batteries in this sector is unlikely to affect the capital market for lithium-ion batteries as a whole. In his view, this policy was already within the consensus and expectations of the industry. Regarding the development of sodium-sulfur batteries in China, Lu Yaxiang said that high-temperature sodium-sulfur batteries are not yet in use in the country, and their prohibition in large-scale electrochemical energy storage stations may slow down the pace of research on them.

Sodium-ion batteries, flow batteries, and lithium batteries designed for energy storage are likely to stand out. Lu Yaxiang told reporters that organic sodium-ion batteries, solid-state sodium-ion batteries, and aqueous sodium-ion batteries are all suitable for medium and large-scale electrochemical energy storage stations. She explained that sodium ions batteries require abundant and inexpensive sodium resources, do not suffer from over-discharge, and thus offer better safety performance. Since medium and large-scale electrochemical storage stations do not require high battery energy density, sodium-ion batteries with lower energy density also have applications. “Furthermore, it has been found that sodium-ion batteries also exhibit good fast-charging performance and wide-temperature adaptability. ” In June 2021, Zhongke Haina – the first high-tech enterprise in China dedicated to the research, development, and production of sodium-ion batteries, established with the support of the Institute of Physics of the Chinese Academy of Sciences – unveiled the world’s first 1 MWh sodium-ion battery energy storage system. Lu Yaxiang is one of the members of this “battery ** team”. She told reporters that the sodium-ion batteries developed by the team do not need to operate under high temperatures; their working principle and battery components are similar to those of lithium-ion batteries, and they can be referred to as room-temperature sodium-ion batteries. The cathode material for batteries can be transition metal oxides, polyanionic materials, prussian blue compounds, etc., while the anode material is typically amorphous carbon; sodium ions are stored in these cathode and anode materials. Vanadium batteries are currently the typical representative of flow batteries. Flow battery energy storage technology achieves the conversion between electrical energy and chemical energy through reversible redox reactions of the active substances in the electrolyte solutions at the positive and negative electrodes. It features the ability to independently design output power and capacity, high safety, long lifespan, and environmental friendliness.

In addition, Lu Yaxiang also mentioned aqueous alkali/metalloid ion batteries. She pointed out that water is a natural flame retardant; water-based batteries are less likely to catch fire or explode under extreme conditions or in cases of thermal runaway, which meets the safety requirements for energy storage systems. Moreover, they possess environmental benefits. Returning to lithium-ion batteries, Chen Yongchong believes that specialized batteries with high safety and large capacity, based on lithium iron phosphate materials, will represent the trend in the application of electrochemical energy storage technologies both domestically and internationally. Through years of research, Chen Yongchong’s team has developed a new type of lithium slurry battery suitable for large-capacity energy storage. The electrodes of these batteries are entirely or partially composed of lithium-storage active materials in slurry form, along with conductive agents and electrolyte. Additionally, they utilize composite current collectors, ultra-thick electrodes, and a semi-open battery structure, thereby completely changing the hazardous nature of lithium-ion batteries. In 2019, research on new lithium slurry-based energy storage batteries was selected as one of the **transformative technology areas, and demonstration projects are currently being carried out. “Batteries designed for ultra-large capacity or ultra-high power energy storage represent the direction of development in industrial technology, and comprehensive technological breakthroughs will still be needed in the future. ”Chen Yongchong said. China Science News (August 1, 2022, Page 4: Science and Innovation)

Professional technical experts still provided guidance on energy storage battery technology and ensured technical quality control for the construction of energy storage projects. From a safety perspective, batteries that use alkali metals as anodes, as well as those that operate at high temperatures, do pose safety risks when used as energy storage batteries. Since such batteries are used on a large scale in concentrated forms, safety considerations must be given top priority. In comparison, flow battery energy storage systems are likely to see significant development in the future, with their advantages of safety, ease of maintenance, and capacity that are not greatly affected by various conditions being their key strengths.

Not long ago, people were talking about the graded use of new energy vehicle batteries after they age; it seems that this approach no longer works