Lithium-ion batteries are rechargeable cells with relatively high power for their size. However, fires caused by these batteries have increased fivefold since 2016, especially in the hot summer. In Vancouver, Canada, alone, seven people have died in fires related to these batteries in 2022. Understanding how Li-ion batteries fail and spotting early signs of a fire is crucial.
What is the difference between Lithium batteries and Li-ion batteries?
Lithium batteries, also known as primary batteries, these are single-use and cannot be recharged. They contain highly combustible lithium metal and offer extremely high energy densities in small configurations, ideal for applications where recharging isn't necessary or feasible.
Li-ion batteries, or secondary batteries that are used worldwide, provide high energy density though lower than the lithium primary and can be recharged again and again. These batteries contain no free lithium metal but do contain lithium ions and highly flammable electrolytes.
How do Li-ion batteries work?
Li-ion batteries were first commercialized by Sony in 1991 for handheld video recorders. In 2008, Tesla introduced the first battery-powered electric vehicle. Today, these batteries power everything from laptops and cell phones to electric vehicles, hospital equipment, and energy storage systems.
A Li-ion battery pack consists of several Li-ion cells stacked together in modules, along with temperature sensors, voltage taps, and an onboard computer (Battery Management System) to manage the individual cells. Each cell has a positive electrode (cathode), a negative electrode (anode), and an electrolyte in between. The anode is typically made of graphite, while different lithium materials are used for the cathode, such as Lithium Cobalt Oxide (LCO) and Lithium Nickel Manganese Cobalt (NMC).
During charging, lithium ions move from the cathode to the anode through the electrolyte, while electrons flow externally in the circuit. During discharge, the ions move back to the cathode, and the electrons power the connected application. Once all ions have moved back to the cathode, the cell is completely discharged and needs recharging.
How do Li-ion batteries catch fire?
Li-ion batteries can spontaneously ignite and explode due to overheating from electrical shorting, rapid discharge, overcharging, manufacturing defects, poor design, or mechanical damage. Overheating triggers thermal runaway, a chemical reaction that rapidly increases the battery's internal temperature and pressure. This can cause a white vapor cloud of toxic, flammable gases, including hydrogen fluoride, leading to fires and potential explosions.
The development process of a Thermal runaway event
Thermal cameras can help
Thermal imagers are essential for inspecting the production and storage of Lithium-ion batteries. Active thermography can detect hotspots by scanning the full temperature distribution on the battery pack surface at an early stage, giving the system and operators time to activate countermeasures.
A thermal runaway event and its development process captured by a thermal imager
The 600 Series cameras are designed to work in harsh environments at temperatures between -25° to 65°C. Among them, 600CH cameras have a temperature detection range between -20° to 2000°C for discovering chemical fires and other extreme industrial fire conditions. >> Find more about 600s
During the 24/7 continuous monitoring without supervision, an alarm can be triggered automatically when the pre-set critical temperature is exceeded, and heat sources can be localized immediately, even in dusty or smoke-polluted environments. Besides, the camera feed of multi-camera systems can be routed to the control room through ethernet cables, and radiometric video streams can be recorded at 30Hz automatically or manually.
By using FOTRIC thermal cameras, potential issues can be identified early, reducing the risk of fires and ensuring safer battery operation and storage.
[1] What is thermal runaway? www.evfiresafe.com
[2] Battery Safety: Top 5 Reasons why Lithium-Ion Batteries Catch Fire. www.ionenergy.co
[3] Battery Inspection Using Advanced Thermography. www.movitherm.com
[4] Korean energy storage system fires blamed on lithium-ion battery faults. www.bestmag.co.uk