A fire and explosion occurred in an energy storage power station in Germany! Battery safety is a matter of renewed concern

　　Energy storage safety is the cornerstone of everything.

　　According to foreign media reports, recently, a lithium battery energy storage container in a commercial area in Germany caught fire, and in the process of firefighting, due to the opening of the smoking container, an explosion with flame flashes occurred instantly, resulting in two firefighters injured. Several smaller explosions followed, after which firefighters used a crane to move it to a nearby open field, and finally completed the extinguishing of the fire in about 10 hours.

　　According to related reports, the manufacturer of the battery energy storage system that exploded this time is the German company INTILION. According to the company's official website, the company's energy storage products currently use lithium iron phosphate batteries.

　　After this incident, the energy storage industry, which is unprecedentedly hot and prosperous, has once again sounded the safety alarm. At the same time, it has also triggered extensive thinking and discussion in the industry, under the demand for extreme cost reduction, energy storage cells and systems continue to develop towards a "bigger" trend, and the high internal temperature of ultra-high-capacity batteries is more likely to induce accidents, so how to ensure the safety of energy storage and resolve this risk?

01

Global energy storage accidents are frequent, and many aspects such as operation and maintenance, fire protection and other aspects need to be improved

　　In fact, the explosion accident of the lithium battery energy storage power station in Germany is not an isolated case. According to public reports, there are currently more than 5,000 energy storage power stations (excluding households) in the world, and there are more than 70 fire accidents, which is equivalent to a fire probability of about 1.52%. However, most of the accidents occurred in overseas regions, and most of the products came from overseas head energy storage integrators. The German company INTILION is a subsidiary of Hoppecke Batteries. According to the data, the latter is one of the largest manufacturers of industrial battery systems in Europe.

　　Some industry insiders believe that energy storage batteries will release combustible gases such as hydrogen, carbon monoxide, and methane in the event of thermal runaway and thermal diffusion, and when they reach a certain concentration, they will combine with oxygen in the air and trigger a fire or even an explosion under suitable conditions. In this fire accident, the firefighters directly opened the "smoking" container, and then a flash explosion occurred, exposing that there are big problems in the operation and maintenance of energy storage power stations, both abroad and at home.

　　"At present, there is a lack of full-time energy storage operation and maintenance personnel in the entire industry." Experts from Datang Central and South Institute pointed out that in the early warning stage, as well as the detection and suppression of early fires, it is necessary to use big data for management, and how to make good use of digital technologies such as remote control, BMS, EMS, AI, etc., to truly play the role of early warning and timely stop loss is also a problem that the industry needs to solve.

　　On the other hand, whether it is inside the energy storage system or the energy storage power station, there will be corresponding fire safety configurations. Some industry insiders believe that the current foreign market does not pay much attention to energy storage fire protection. Moreover, the investment in energy storage and fire protection in the domestic market is also low.

　　In terms of fire protection configuration of energy storage systems, according to Battery China, domestic battery companies mainly ensure the safety of the system when the battery is thermally out of control by setting up combustible gas detectors, active exhaust devices, explosion-proof pressure relief devices, and gas fire extinguishing. Depending on the project configuration, fire extinguishing media such as dry powder, gas and liquid are used to extinguish the fire in one or more times and prevent recurrence. In view of the investment level of energy storage fire protection in China, relevant experts from the Fifth Institute of China Nuclear Power pointed out that the fire protection configuration of the system and the automatic fire alarm control system of the energy storage power station account for less than 2% of the investment in the entire energy storage power station, and the investment is low.

02

Critical "cell" safety

　　In fact, operation and maintenance and fire protection are just "remedial" solutions after the battery has thermal runaway. Xu Jinmei, CTO of CATL's Energy Storage Division and President of CATL's Energy Storage Europe Business Department, recently publicly stated that there are only two directions of energy storage safety: "zero accident" and "disaster", and CATL's energy storage safety design concept is prevention in the early stage rather than protection in the later stage.

　　Energy storage safety is a "big topic" of the system, involving multiple components such as battery cells, mechanical parts, and electrical equipment, as well as the whole life cycle of the product itself, such as design, transportation, installation, application, and decommissioning. Among them, the most critical is the intrinsic safety at the cell level. This is also one of the reasons why every time a fire and explosion accident occurs, often the real "culprit" has not yet been clarified, and the battery cell has become a "man behind the pot".

　　At the level of battery cell materials, most of the fire and explosion accidents in the early stage were Japanese and Korean ternary material energy storage batteries, while China's energy storage batteries mainly chose safe and reliable lithium iron phosphate battery routes. In the fire accident of the energy storage power station in Germany, the battery products are also lithium iron phosphate cells, which means that even if the lithium iron phosphate material with better thermal stability is used, the material itself cannot guarantee the absolute safety of the battery.

　　From the perspective of material intrinsicism, lithium iron phosphate materials are safer than ternary material batteries, so the lithium iron phosphate route is generally chosen in domestic energy storage projects. "In essence, this is true for small lithium iron phosphate batteries", Ouyang Minggao, an academician of the Chinese Academy of Sciences, affirmed this. However, he also pointed out that "the internal temperature of a large-capacity battery can exceed 800 degrees, which exceeds the temperature of lithium iron phosphate cathode decomposition", and "we should pay special attention to the risk of gas explosion", which also provides us with an extremely important warning role.

　　"All things are foreseen." In China, the technology in the field of lithium iron phosphate batteries is earlier, the industrial chain is more mature, the lithium iron phosphate for energy storage is developed earlier, and the safety system is more sound. From another point of view, foreign lithium iron phosphate energy storage batteries may be quite different from China at the technical level. However, in any case, especially in the current process of energy storage cells produced by Chinese battery companies moving towards higher energy density, it is more necessary to ensure that large-capacity energy storage cells have higher safety performance by continuously optimizing the process, innovating the structure, and improving the technology.

　　In terms of the overall safety of energy storage, domestic enterprises have tested from multiple dimensions of mechanism, electrical performance, safety and reliability to ensure safety performance. For example, in order to ensure the effectiveness of the technology, CATL has built a safety demonstration platform to simulate the safety demonstration of energy storage systems in different power grid scenarios and operating environments. In April this year, CATL's "Tianheng" energy storage system was released, and according to reports, the cell failure rate of its "Tianheng" energy storage system can reach the PPB (parts per billion) level.

　　Although this incident occurred abroad, it has also aroused widespread concern in the Chinese market, and we should be vigilant. Battery China also calls on the government, enterprises and the whole industry to pay serious attention to the healthy development of the energy storage industry, establish and improve the standards and supervision of the energy storage industry as soon as possible, standardize the design of all aspects of the energy storage power station, and at the same time do its best to eliminate any possible risks and hidden dangers through technological improvement.