Welcome back to The Battery Buildout.
In Episode 01 of “Battery Gigafactory Building Practice” series, we covered the strategic, compliance, supply chain, delivery and talents foundations of a global battery gigafactory. Last episode we discussed how utilities and micro-environment control determine the factory's energy footprint. This edition addresses the risk that sits at the intersection of all these systems: thermal runaway, fire suppression, and the environmental closed loop. These are not safety features to be added after the process is designed. They are design constraints that shape the process itself.
Table of Contents
1. Thermal Runaway Is a Chain Reaction, Not an Event
Let’s start from thermal runaway, thermal runaway is often described as a single event—a cell catches fire. It’s incomplete. Thermal runaway is a self-sustaining chemical chain reaction that propagates from cell to cell, from module to module, and from workshop to workshop if the factory is not designed to stop it.
The propagation mechanism is physical. When a cell enters thermal runaway, it releases energy that heats adjacent cells. If the adjacent cell reaches its own critical temperature, it enters thermal runaway as well, releasing more energy and heating the next cell in sequence. The result is a cascading failure that can consume an entire formation and aging room in minutes.
This is why the most important fire safety question in a gigafactory is not “how do we put out a fire?” It is “how do we prevent propagation?” The answer is not a single system. It is an architecture of separation, detection, suppression, and ventilation that must be designed as an integrated whole.
Then how we define the “safety” for system?
2. The Testing Standards That Define What “Safe” Actually Means
You could find more local reference frameworks for lithium battery fire safety.
The critical insight is that these standards are not just test protocols. They are design constraints. They define where separation is required, how much separation is required, and what evidence must be provided to demonstrate that separation is effective. A factory that does not design following standards from the beginning will discover during permitting that its layout cannot be approved.
Basing on standards, we carry out practical applications, let’s turn to the suppression system.
3. Why Gas-Phase Suppression Alone Is Not Enough
Clean agent suppression systems such as FK-5-1-12 are widely used in battery manufacturing facilities. They are effective at extinguishing open flames without damaging equipment.
But there is a critical limitation. Recent research comparing fire extinguishing agents for controlling thermal runaway propagation in lithium-ion batteries found that while FK-5-1-12 exhibited the best cooling performance among gas-based agents, water-based extinguishing agents demonstrated superior cooling performance overall.
The reason is physical. Gas-phase agents suppress combustion by disrupting the free-radical chain reaction. They stop the flame but do not remove the heat. In a lithium battery fire, the heat is the problem. The cell continues to generate heat internally even after the flame is extinguished. Without effective cooling, the cell will re-ignite, and propagation will continue.
This is why modern designs for formation and aging areas typically combine gas-phase suppression with water-based cooling. The gas agent handles the initial flame suppression. The water system handles the heat removal and propagation prevention. Neither system alone is sufficient.
Then how about the detection?