Core Monitored Gases: Key Risk Sources in Energy Storage Scenarios

The gas risks in the energy storage industry are closely related to energy storage technology types, battery material systems, and auxiliary systems, primarily involving the following five categories of gases:

1. Lithium-Ion Battery Energy Storage Systems (Mainstream Technology)

● Carbon Monoxide (CO): Generated during battery overcharging, over-discharging, short-circuiting, or thermal runaway, when negative electrode materials (e.g., graphite) react with the electrolyte (e.g., carbonate solvents) to produce CO (colorless, odorless, and 200–250 times more affinity to hemoglobin than oxygen, causing hypoxia in humans).

● Hydrogen (H₂): May be produced by internal diaphragm damage or electrolyte decomposition in batteries, especially under high temperatures or mechanical stress. Though present in trace amounts, its explosion limit is 4%–75%, making it a high-risk gas.

● Organic Solvent Vapors (e.g., Carbonate Solvents: EC, DEC, DMC): Key components of electrolytes (accounting for 70%–80% of electrolyte mass), these solvents have low flash points (e.g., ethylene carbonate (EC) flash point: 160°C) and volatility. Leaks can form explosive mixtures with air (e.g., diethyl carbonate (DEC) explosion limit: 1.3%–8.5%).

● Hydrogen Fluoride (HF): A toxic byproduct of lithium salt (e.g., lithium hexafluorophosphate (LiPF₆)) decomposition when exposed to water or high temperatures, HF is highly corrosive (causing deep tissue burns upon skin contact and respiratory damage upon inhalation) and a typical toxic emission during battery thermal runaway.

● Phosphine (PH₃), Hydrogen Sulfide (H₂S): Rare in mainstream systems but possible in special battery chemistries (e.g., phosphorus- or sulfur-containing positive electrode materials), these gases are highly toxic (PH₃TLV-TWA: 0.3 ppm; H₂S explosion limit: 4.3%–5%).

2. Flow Batteries (e.g., All-Vanadium Flow Batteries)

● Sulfuric Acid Mist (H₂SO₄): The electrolyte (e.g., vanadium sulfate solution) is highly corrosive. Leaks from storage tanks or pipelines release sulfuric acid mist, which corrodes equipment and irritates the respiratory tract and eyes, potentially causing pulmonary edema at high concentrations.

● Hydrogen (H₂): Some flow batteries (e.g., zinc-bromine flow batteries) may produce hydrogen during charging due to side reactions, requiring monitoring to prevent accumulation.

3. Sodium-Ion Batteries and Lead-Acid Batteries

● Lead Smoke/Dust (Lead-Acid Batteries): Charging may release trace lead compounds (e.g., lead oxide), causing long-term lead poisoning (neurological damage). Sodium-ion batteries, during thermal runaway, may produce similar CO, HF, and organic vapors as lithium-ion batteries.

4. Hydrogen Energy Storage (e.g., Hydrogen Fuel Cells, High-Pressure Hydrogen Tanks)

● Hydrogen (H₂): The core medium for hydrogen energy storage, produced via electrolysis or stored as high-pressure gas. Leaks from pipelines, valves, or tanks (hydrogen is lighter than air, density: 0.089 kg/m³) can accumulate in roofs, pipe gaps, or tank tops. With an extremely wide explosion limit (4%–75%), even trace concentrations can trigger explosions.

● Oxygen (O₂): A byproduct of electrolysis (1 volume of O₂generated per 2 volumes of H₂), high-concentration oxygen (>23.5% VOL) mixed with hydrogen significantly expands the explosion range, necessitating monitoring to prevent oxygen-enriched environments.

5. Physical Storage (e.g., Compressed Air Energy Storage, Flywheel Energy Storage) and Auxiliary Systems

● Lubricating Oil Vapors: Compressors in compressed air energy storage or bearing lubrication systems in flywheel energy storage may leak oil vapors (VOCs), causing long-term respiratory issues if inhaled.

● Sulfur Hexafluoride (SF₆): High-voltage electrical equipment (e.g., GIS switchgear in power conversion systems (PCS)) uses SF₆as an insulating medium. Leaks can lead to oxygen depletion (O₂ <19.5% VOL) and greenhouse gas emissions (SF₆ has a global warming potential 23,500 times that of CO₂).