Battery fire prevention is still the key. How does LG design energy storage fire prevention systems?

After Samsung SDI began to deploy fire protection systems on energy storage battery systems, LG Chem also started to develop fire protection systems based on its own energy storage battery systems. From the information disclosed so far, LG Chem is considering using an external water circuit, through an independent water tank, and then configuring it on each module.

According to information disclosed by LG Chem, a sprinkler device is installed on each battery module. By installing an independent water tank near the battery rack (the design of this water tank should have a certain capacity requirement and require external water supply facilities), connecting pipes to each module connected to the back of the battery rack, and spraying water when smoke or heat is detected, thermal runaway is prevented.

Considering that water will have a counterproductive effect on the module that has already caught fire, this system will not spray water directly on the battery module with fire. Instead, it will spray water near the battery to prevent the temperature from rising.

LG Chem obtained UL9540A certification through this method. Refer to the previous experimental results "LG's energy storage module and pack design" and "Thermal runaway experiment conducted by NEC"

CMA Thermal Diffusion Process (15 minutes)

According to the experimental results, it has expanded to a total of 6 modules, which means that if a single battery cell breaks through the CMA or the module, the affected range is very large.

According to the experimental results with NEC, the water nozzle above the energy storage cabinet rack started 63:26 minutes after the experiment started to lose control, and started 26:54 after the thermal runaway. After 30 seconds of water spraying, the room temperature was lower than 175°C. During the whole process, the heat propagation process was that the temperature of the adjacent rack rose to about 100°. In other words, according to the design of this battery cell, if it meets the UL 9540A test standard, the energy storage system needs to be equipped with an automatic fire extinguishing agent and a water spray suppression system.

Therefore, it is not clear whether the ESS previously made by LG Chem in Korea should be fully protected according to this system, but it is necessary to add safety measures, and cooling the edge area after thermal runaway is essential. In addition to this measure, LG Chem has also added battery module fuses, surge protectors and rack fuses on the original basis to protect the battery from problems caused by external loads during operation.

After the Korean energy storage investigation, LG's energy storage systems have had problems one after another. LG is currently conducting experiments and analysis to find out the exact cause of several fire accidents in October. At present, in order to prevent more fires, LG has set the SOC upper limit of the energy storage battery to 70% (previously set at 95%). On October 21, at an LG solar photovoltaic power station in Hadong County, South Korea, the energy storage battery ESS installed a 1.3MWh battery system from LG Chem. These batteries were produced at the LG Chem Ochang factory, and the previous 14 accidents were mainly concentrated in the products produced by LG Chem's Nanjing factory in China in Q2 2017.

Summary: Some problems are common to several power battery companies around the world. The ESS problem in Korea is not so easy to solve (LG Chem has a total of 500 domestic ESS stations in Korea, with nearly 1GWh of batteries)

References:
1) kidd.co.kr

2）ETNEWs