SHANGHAI, June 13, 2025 /PRNewswire/ — On June 11, 2025, at the 18th SNEC, Hithium, a leading global energy storage technology company, held a product safety technology sharing event themed Leading the Future, Forged for Safety and unveiled the full results of the world’s first all open-door large-scale fire test of its ∞Block 5MWh energy storage system, and was also awarded the large-scale fire test certification by international testing authority UL Solutions.
Hualei Wang, project manager for the fire test, shared an overview of the test background and key details. A video of the open-door fire test was also shown on-site, offering a comprehensive view of the test procedure, technical highlights, and results.
The open-door fire test was initiated by intentionally heating eight battery cells inside container A to trigger thermal runaway, causing propagation between cells. As the battery’s pressure relief vents opened, an ignition system ignited the released gases, initiating full combustion with the container doors kept wide open to allow continuous oxygen flow. This setup maximized heat exposure to adjacent containers B, C, and D. The test was conducted under four extreme conditions: all open-door combustion, dual 15 cm extreme spacing, fire suppression system deactivated, and 100% State of Charge (SOC).
- Peak Fire Phase: At the fourth hour of testing, the fire reached its peak temperature of 1,372°C. Temperature monitoring confirmed that cell temperatures in all adjacent containers remained well below the cell thermal runaway initiation threshold defined by the UL9540A cell-level test (≤42°C in Container B, ≤80°C in Container C, and ≤70°C in Container D).
- Sustained Combustion Phase: After 15 hours of combustion, the open flame was extinguished. The initiating container remained structurally intact without deformation or collapse. No combustion or thermal runaway propagation occurred in the three adjacent containers. Containers B, C, and D only experienced minor surface damage, while internal battery modules remained completely unaffected.
The completion of the test was made possible by Hithium’s multi-layered safety architecture, spanning the cell, module, and system levels. At the cell level, heat-resistant anode/cathode materials, functional electrolyte additives, and high-temperature separators raised thermal thresholds. At the module level, low-conductivity insulation and flame-retardant top covers minimized propagation risk. At the system level, a high-strength container frame and heat-resistant enclosure materials maintained structural stability under extreme heat.
At the event, UL Solutions awarded Hithium a certification for the large-scale fire test, recognizing its compliance with UL 9540A and NFPA 855 standards. Qifeng Xiao, General Manager of the Energy and Automation Division, Asia Pacific at UL Solutions, stated at the certification ceremony, “Hithium’s pioneering open-door extreme fire test was the first to be conducted under full oxygen exposure—far beyond the industry standard closed-door with explosion vent fire test model. The positive outcome not only validated the system’s self-contained fire protection, but also established a valuable reference for the development of global energy storage safety standards through the world’s first open-door fire test.”
This pioneering fire test not only demonstrated Hithium’s strong technical capabilities but also reflected its full confidence in the safety performance of its energy storage systems through a fully transparent testing process, contributing important data and practices to the industry. Hithium will continue to invest in safety innovation—tightening the “seatbelt” for the global transition to green energy.
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