Defective battery cells were the cause of a series of energy storage system fires in Korea, a panel of experts has told the country’s government.
Electric engineering experts at public and private institutions under the country’s Ministry of Trade, Industry and Energy said defects caused four out of five energy storage systems (ESS) failures, reported news outlet The Korea Herald on 6 February
Of the five ESS sites that caught fire last year, four involved systems built by Korean battery giants LG Chem and Samsung SDI. Both companies refute the panel’s findings.
At LG Chem’s ESS sites in Yesan and Gunwi ignition points were in the batteries according to operation records of the systems, the ministry’s panel found.
The panel found some foreign fragments adhered to the cathode plates and lithium deposits in the separators of the system, and some traces of meltdown in the batteries of the burnt systems collected from the sites.
By examining similar batteries in Gunwi, the panel said it found some anode active materials.
The investigative group cited “erroneous charging and discharging processes” as the cause of the fires at Samsung installed ESSs in Pyeongchang and Gimhae.
At the Pyeongchang site, the system energy management system revealed the power voltage rose above the maximum level set for charging and fell below the minimum level for discharging.
At the Gimhae site, the panel found the voltage deviation in the system showed an increasing trend for the past six months.
“The meltdown imprints alone are insufficient to prove that the ignition points were inside the batteries,” LG said in its statement to The Korean Herald. “Such vestiges can be left inside the batteries even if the fires had ignited in the other parts of the system, not the batteries.”
Last year, there were a total of 23 accidents that involved the firms’ ESS products among some 1,490 ESS facilities across Korea, reported The Korean Herald. The Industry Ministry investigated 23 of them and announced the results in June.
Operations were suspended at 522 ESS facilities, around 35% of the country’s ESS facilities, reported The Korea Herald last June.