Panoramic analysis of the safety of all-vanadium flow batteries

Written in front

In the past five years, 94% of global energy storage power plant fire accidents were related to lithium-ion batteries. At the same time, all-vanadium flow batteries (VRFBs) still maintain the record of "zero ignition and explosion". However, "safety" is not a binary proposition, and this article makes a "microscopic" disassembly of VRFB safety based on the latest public research and engineering data

Intrinsic safety determined by technical principles

Aqueous electrolyte: dilute sulfuric acid vanadium ions, no flammable organic solvents, fundamentally eliminating thermal runaway conditions.
Energy-power decoupling: energy is stored in an external tank, and the stack only provides a reaction site; Even if the stack is short-circuited, only the mechanical energy of the electrolyte circulation pump is released, and no chemical energy is instantaneously released.
The electrode does not participate in lithium storage: no dendrites, no SEI film decomposition, and the physical level avoids the internal short circuit trigger

Operational safety – the numbers behind the "zero explosion" record

Cycle life: The capacity retention rate is >80% after 15 000–20 000 times, and the aging process is slow, and there is no risk of sudden heat loss due to performance degradation.
• Temperature window: 0–45 °C, temperature control is required, but does not trigger chain exothermic; >45 °C only produces V₂O₅ precipitation affecting efficiency, not exothermic reactions.
• Gas management: extreme overcharging or diaphragm failure can cause hydropower to resolve H₂/O₂, design codes require forced ventilation and hydrogen concentration ≤ 4% (1/4 lower explosion limit)

conclusion

In terms of intrinsic safety, VRFB is "non-flammable and non-explosive" with its aqueous electrolyte and physical isolation architecture, which is significantly better than lithium batteries.
In extreme scenarios, it is still necessary to focus on the secondary risks of strong acid corrosion, toxic gas and heavy metal leakage; Through material improvement (low hydrochloric acid formula), engineering protection (double-layer anti-seepage, accident pool) and strict operation and maintenance, the personal risk value can be controlled below 1×10⁻⁶/year, and meet the individual acceptable risk benchmark in China's Interim Regulations on the Supervision and Administration of Major Hazard Sources of Hazardous Chemicals.
In the future, with the implementation of GW-level projects, it is recommended to establish a "vanadium electrolyte leakage emergency technology alliance" to unify leakage plugging, wastewater treatment and health monitoring standards, and keep the bottom line of safety for large-scale promotion of the industry.