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Safety First: How Vanadium Sheets Build a Firewall for the Energy Storage Era

In July 2025, an explosion at a lithium battery factory in Kaohsiung, Taiwan, once again sounded the alarm for safety in the energy storage industry—the burns to firefighters and the rekindling of the fire exposed the technological weakness of lithium batteries: thermal runaway. Meanwhile, in Switzerland, a 50-liter electrolyte leak occurred in the basement of an apartment building's vanadium redox flow battery, but the crisis was resolved simply through neutralization and recovery, without causing any casualties or environmental pollution. This stark contrast brought vanadium redox flow battery technology, with vanadium sheets as its core material, into the public eye. In today's era of explosive growth in energy storage demand, vanadium sheets, with their inherent safety characteristics, are becoming a key force in overcoming the energy storage safety dilemma.

The support of vanadium sheets for energy storage safety stems primarily from the inherent chemical advantages of the electrolytes derived from them. The core active material of the vanadium redox flow battery comes from the electrolyte prepared by dissolving vanadium sheets. This electrolyte uses dilute sulfuric acid as a solvent and is a typical water-based system, fundamentally different from the organic electrolytes used in lithium batteries. Organic electrolytes are highly volatile and flammable, and will burn rapidly when exposed to high temperatures or open flames. In contrast, the water-based electrolyte made from vanadium sheets is non-flammable, eliminating the material basis for combustion and explosion at its source. More importantly, the multivalent nature of vanadium allows the positive and negative electrode electrolytes to use a homologous vanadium ion system, avoiding the safety risks caused by cross-reactions between different metal ions. Even when the positive and negative electrode electrolytes are artificially mixed at 100% charge, the system temperature only rises from 32°C to 70°C, far below the danger threshold.

Independent testing according to UL 9540A standards has confirmed that the vanadium redox flow battery with vanadium sheets at its core has no risk of thermal runaway. Even when exposed to an external fire environment, its chemical and thermal stability remains intact. This contrasts sharply with lithium batteries: lithium batteries are highly susceptible to thermal runaway under conditions such as overcharging, short circuits, and impacts. Once ignited, they continuously release high temperatures and toxic gases, requiring continuous cooling and waiting for the reaction to subside during firefighting, posing a significant challenge to rescue efforts. In contrast, vanadium-based energy storage systems do not experience thermal runaway or produce toxic gases like chlorine, thus establishing the first line of defense at the chemical reaction level.

The safety of vanadium-supported energy storage is further enhanced by a system guarantee of "physical structural design + multiple protections." The all-vanadium redox flow battery employs a unique "stack-tank separation" architecture. The electrolyte, made of vanadium sheets, is stored in a separate external tank, physically isolated from the stack where the electrochemical reaction occurs. This design completely separates energy storage and energy conversion processes spatially. Even if the stack fails, it will not affect the stability of the electrolyte in the tank; conversely, even if the tank leaks, it will not trigger an electrochemical runaway reaction. In the Swiss battery leak incident, it was precisely this separation structure that ensured the leaked 50 liters of electrolyte represented only 10% of the system's total capacity, and prevented it from affecting adjacent energy storage units, thus minimizing the impact of the accident.

In terms of protective design, the vanadium sheet energy storage system incorporates the concept of "safety redundancy." Modular units are equipped with electrolyte storage tanks that are never pressurized, preventing explosions due to sudden pressure increases even in the event of an anomaly; the built-in secondary containment device can hold the entire liquid volume, completely eliminating the risk of leakage and spread. Even more noteworthy is the "true power-off" design—after the system is shut down, very little residual electrical energy remains in the stack, significantly reducing the risk of electric shock to maintenance personnel and emergency responders. In contrast, lithium battery energy storage containers not only require maintaining a safety distance of several meters, but the residual electrical energy inside can also continue to pose a safety threat after an accident. This safety design, from structure to details, allows the vanadium sheet energy storage system to remain controllable even in extreme situations.

From industrial application practice, the safety advantages of vanadium sheets have been verified in multiple scenarios. In the 100 MWh/400 MWh vanadium redox flow battery project in Hami City, the aqueous electrolyte prepared with vanadium sheets enables the system to operate stably under normal temperature and pressure conditions of 35-45℃, completely eliminating the risk of flammability and explosion. As a benchmark project at the 100 MWh level, this project has achieved continuous and stable operation and improved the capacity for renewable energy absorption. In a data center in Zhejiang, a 2MW/8MWh vanadium sheet energy storage system withstood foam fire extinguishing agent spray tests, perfectly meeting the security requirements of critical infrastructure. In the extreme environment of the Qinghai Oilfield at an altitude of 3200 meters and a temperature difference of 75℃, the vanadium sheet energy storage system operated stably for 180 consecutive days, demonstrating its safety and reliability under harsh conditions.

For scenarios with "zero tolerance" for safety, such as hospitals, substations, and rail transit, the value of vanadium sheet energy storage systems is even more prominent. In such scenarios, an energy storage accident could trigger a chain reaction of power outages, equipment damage, and even casualties. The inherent safety characteristics of vanadium sheets can ensure the stability of energy supply from the ground up. In the 300MW/1200MWh energy storage project planned for New Area, the 200MW/800MWh vanadium redox flow battery portion is designed with safety in mind, complementing lithium iron phosphate batteries to provide a safety barrier for high-proportion renewable energy integration.

As the energy storage industry shifts from prioritizing capacity to prioritizing safety, vanadium sheets are reshaping energy storage safety standards due to their inherent chemical safety, structural design safety, and proven safety in practice. Although vanadium sheet energy storage systems do not match the energy density of lithium batteries, their irreplaceable safety makes them the preferred technology for long-term, large-scale, and critical energy storage scenarios. With the upgrading of high-purity vanadium sheet preparation technology and the improvement of recycling systems, vanadium sheets will not only continue to solidify their position as a "firewall" for energy storage safety but will also provide safe and controllable core support for global energy transition.

AlloyHit specializes in producing vanadium sheets, vanadium rods, vanadium wires, vanadium targets, and vanadium tubes in various specifications.