On Aug. 20, a lithium-ion battery that a bus passenger was carrying caught fire, soon engulfing the whole vehicle in the eastern city of Nanjing. The blaze left two people, including a child, dead and five more injured.

On Aug. 23, an electric battery being charged on a balcony in Huizhou City in the southern Guangdong province exploded around midnight. While no casualties were reported, the blast caused minor structural damage.

And on Aug. 7, a malfunctioning electric bike stored inside a van caught fire in the eastern Anhui province, eventually destroying the whole vehicle.

Across China, more and more lithium-ion batteries, commonly used to power e-bikes, are catching fire or exploding, underscoring a pressing need for more safety measures and regulation. 

Speaking to Sixth Tone, experts say that the increasing number of fires highlights the potential hazards associated with cheap but subpar batteries, particularly in a country where demand is now outpacing current safety regulations. China issued new national standards for electric vehicles and batteries in 2020.

Data shows that e-bikes are already among the most popular modes of transport. According to the China Bicycle Association, around 50 million e-bikes were sold across the country in 2022. And in all, at least 350 million e-bikes have been registered — that’s around one for every five Chinese.

But mishaps have surged, too.

According to China’s National Fire and Rescue Administration, in the first half of 2022, a total of 8,370 e-bike fire cases were reported, up 31.3% compared to the previous year.

In 2023, the National Fire and Rescue Administration found that 42.9% of all fires in homes across the country were caused by electrical issues. Overloading, unauthorized connections of wires, and illegal charging posed the biggest risks.

Most electric battery-related incidents stem from factors like overcharging or short circuits while using incompatible charging docks that lead to overheating and, in some cases, explosions.

Sometimes, temperatures within a battery that’s being overcharged can rapidly reach 900 degrees Celsius in just three minutes, often leading to fires that spread quickly due to the flammable materials used in such batteries.

Experts say that lithium is among the most difficult elements to control after combustion. Once exposed to air, it can react with oxygen, which can further result in intense combustion and even explosions.

Speaking with Sixth Tone, Bo Shouhang, from the Global Institute of Future Technology at Shanghai Jiao Tong University, explains that the rapid growth of the electric battery market in China has far outpaced the technological maturity required to ensure safety.

China is now the world’s largest producer, consumer, and exporter of e-bikes, and the market is still growing. Amid such high demand, consumers constantly seek batteries that are light and last longer, which means their capacity must also increase.

He Xiangming, director of the Materials Chemistry and New Energy Lab at Tsinghua University and a pioneer in lithium-ion battery research, underscores that improving battery technology is a delicate and time-consuming process.

“Scientists still aren’t completely clear about how safe lithium is because the whole system is very complex. What chemical reactions happen inside the battery? You can’t directly see and touch that molecular atomic level,” says He.

Furthermore, he says, scientists face challenges in determining the exact reason for such fires, since most occur at random. This makes it difficult to fully reconstruct the process and pinpoint the exact causes and timing.

He says his biggest concern is the regulation and supervision of the e-bike market, particularly low-end models. The influx of cheap, low-quality batteries entice more buyers, who are often unaware of the potential hazards.

Although the type of batteries may vary, most are easy to purchase online. Typically, a lithium-ion battery costs between 600 and 2,000 yuan ($82-$274). Some models are available for as low as 500 yuan.

According to He, the size of the market poses challenges. “First, the administrative aspect is complex. Second, a lack of a reliable safety assessment system makes it hard for consumers to gauge the risks. Also, many products purchased online have short lifespans, making it difficult to predict safety risks,” he says.

Some smaller businesses might opt to reuse old batteries. And factories selling secondhand electric cores from larger vehicles face challenges, too: The voltage and ability to withstand reactions can vary between batteries, which can potentially lead to overheating.

Asked about the possibility of a warning system to mitigate risks, Bo says that determining when and how to detect signals poses a challenge. “Using voltage, for instance, might be too late for an effective warning,” he says.

“As the industry matures, safety is a process that requires lots of time and resources,” says He. “It’s like ‘school fees’ that need paying.”

Editor:  Guo Lili