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Batteries and Fire (Part 2 – Different Cell Technologies)

02/12/2025

Are all batteries equally safe?

There are several types of energy storage and system topologies among battery systems on the market. These behave very differently depending on the type of cell chemistry they use and how they react in the event of a fire. It should be emphasized, however, that most stationary battery storage solutions available today primarily use LFP (LiFePO4, lithium iron phosphate). This is a thermally stable chemistry that does not experience thermal runaway during a fire.

If we zoom in on the lithium-ion family of batteries, there are several different chemical compositions, each suited to specific applications. For example, NMC (nickel manganese cobalt oxide) offers a good balance between specific energy, specific power, and high performance, making it ideal for electric vehicles and e-mobility applications. If we consider LFP, it scores highly for safety and lifespan while still providing solid performance in terms of both power and energy. This makes it particularly suitable for stationary energy storage.

Within the lithium iron phosphate (LiFePO4, LFP) category, there are further subdivisions into different technologies and product families. One of these is semi solid-state technology. It is still based on LFP but differentiates itself by using a significantly smaller amount of liquid electrolyte. The semi solid-state technology in qapasity’s batteries also relies on this safer type of lithium-ion chemistry.

At qapasity, we are fully convinced that LFP technology is a very safe family of technologies, and through our semi solid-state cells, we have taken the next step to enhance safety even further in our battery systems. Therefore, we have chosen to publish the table below to quantify the different risk aspects between LFP with liquid electrolyte and semi solid-state, without in any way suggesting that LFP is unsafe.

Parameter	Liquid Electrolyte	Semi Solid-State
Volatility	High	Lower
Risk of Thermal Runaway	Higher	Reduced
Flammability	More flammable	Less flammable
Reaction Limitation	Limited	Improved (gel structure)
Safety Margin	Moderate	Higher

Conclusions

There are many different battery technologies on the market, ranging from lead-acid to lithium-ion. Within these categories, there are various subtypes such as NMC, which has been common in electric vehicles, and LFP, which is widely used in both stationary energy storage and electric vehicles. Within the LFP category, there are different product families, including semi solid-state, where a large portion of the liquid electrolyte has been replaced with a gel. This improves safety and reduces the risk of fire thanks to the semi solid-state technology.

It is important to emphasize that a significant number of batteries have been installed in Sweden and around the world over the past 2-3 years, with many more installations to come. Despite this, battery fires remain rare. Always make sure to choose a quality-conscious installer for your energy storage solution and follow the manufacturer’s installation instructions carefully.