The owner of an electric scooter that stole the train was sentenced to 6 years in prison. Can we still ride this scooter with confidence?

In recent years, with the development of battery technology, the mileage of electric vehicles equipped with lithium-ion batteries has continued to increase. Convenient and lightweight electric vehicles bring unparalleled convenience for short-distance use, but sometimes they can also bring disasters.

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While electric bicycles make travel more convenient, accidents such as fires and explosions have been frequently reported. In the minds of many people, safe and easy-to-use batteries seem to have transformed into time bombs that may catch fire or explode at any time.

Recently, a news report about a fire caused by improper charging of an electric vehicle and the person involved was sentenced became a hot topic.

In fact, this is not an isolated case. According to a video conference report held by the Fire Rescue Bureau of the Ministry of Emergency Management on July 20, 2021 [1], from that year to the time of the report, there had been 6,462 electric vehicle fire accidents across the country, causing significant losses to people’s lives and property.

News on battery bike explosion accidents[2]

With the frequent occurrence of electric bike fire accidents and the tragedies caused by them being pushed to the top of the news and social media hot search lists time and time again, the safety issue of electric bikes has also attracted widespread attention and concerns from countless people: If an electric bike explodes, can we still ride it properly?

01

The root cause of battery car explosions lies in lithium batteries

You can ride a battery bike without any worries, but you have to use it correctly. First of all, it should be clear that battery bikes and batteries are not "black boxes" or "time bombs". On the contrary, battery bike explosions often have rules and reasons. In other words, they can be controlled and prevented. Let's analyze the causes of lithium battery accidents.

Most of the new long-range electric vehicles currently on the market use lithium-ion batteries, which are commonly referred to as "lithium batteries". Electric vehicle explosion accidents are basically caused by fire and explosion of lithium-ion batteries.

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The thermal safety issues that may occur in lithium-ion batteries are determined by the materials and working principles they use. During use, organic and inorganic flammable gases and oxygen will inevitably be produced in the battery. The organic electrolyte and lithium-embedded negative electrode in commercial lithium-ion batteries are also flammable and explosive.

Therefore, if lithium-ion batteries and their products are not used correctly, especially in cases of mechanical damage, overcharging and discharging, local overheating, excessive power usage, or over-age use of aging products, lithium-ion batteries are at risk of thermal runaway, fire, or even explosion.

Compared with common fire accidents, lithium-ion battery fire accidents are more dangerous in one aspect: since the flammable battery itself produces oxygen, once a lithium-ion battery catches fire, it is almost impossible to extinguish it by ordinary means, and people can often only wait for the battery to burn out.

Typical characteristics of thermal runaway of lithium-ion batteries [3]. There are three typical abuse modes of lithium-ion batteries: mechanical abuse, electrical abuse, and thermal abuse. The three abuse modes are sometimes interrelated and may eventually lead to battery fire and explosion.

02

Pay attention to these points

Safe driving of electric vehicles

Since lithium-ion batteries have these safety risks, how can we safely use electric vehicles equipped with lithium-ion batteries?

From the perspective of the country and enterprises, as lithium-ion batteries are widely used and rapidly developing towards higher energy density and wider usage scenarios, in response to the safety issues of lithium-ion batteries, R&D personnel from scientific research institutions and enterprises have made many optimizations in reducing electrode gas production, adding flame retardants, designing cooling systems and monitoring battery health.

The Chinese government has also issued a series of relevant standards to ensure the quality and quality control of batteries, and to provide the society with safe and reliable electric vehicles as much as possible. As a consumer, how can you use electric vehicles safely? In fact, it can be summarized in one line:

Follow national standards and listen to the instructions.

Specifically, consumers should use battery vehicles correctly and safely from the following aspects:

1. Buy a regular electric bicycle. The national supervision and random inspection of electric bicycle products implemented by the State Administration for Market Regulation showed that among the 80 batches inspected in 2019, 159 batches inspected in 2020, and 39 batches inspected in 2021, the unqualified rates were 28.8%[4], 15.1%[5], and 25.6%[6] respectively. It should be pointed out that this does not mean that electric bicycles themselves are unreliable, but that there are many brands and models of these vehicles, and the quality is indeed uneven.

Among the key inspection items, chargers and batteries, fire prevention performance, electrical devices, etc. all have a decisive impact on the fire safety of battery vehicles. Therefore, consumers must purchase battery vehicles sold by regular merchants with mandatory product certification. Poor quality batteries, chargers, electrical devices and fire prevention designs may all lead to fires and explosions in battery vehicles, and spontaneous combustion due to electrical failures is also the main cause of fires in battery vehicles.

2. Use the battery car strictly in accordance with the instructions and relevant regulations, and never "arbitrarily" modify the battery car. Specifically, do not modify the battery or motor without permission during use, do not install audio, lighting and other electrical equipment without permission, use the standard charger and power supply that complies with the instructions for charging, and try to avoid long-term charging. These operations may cause circuit system failure and thermal runaway of the battery, and eventually cause a major fire accident.

On the other hand, the “Regulations on Fire Safety Management of High-Rise Civil Buildings”, which came into effect on September 8, 2021, also clearly states: “It is prohibited to park or charge electric bicycles in the public lobby, evacuation corridors, stairwells, and emergency exits of high-rise civil buildings”[7]. Many places have also made clear requirements for the storage of electric bicycles, such as not allowing them to enter elevators. Consumers must abide by relevant regulations when using electric bicycles, for the sake of their own safety, the safety of their neighbors’ lives and property, and the public safety of the community.

3. Do not continue to use expired batteries. Lithium-ion batteries often have a certain working life and storage life. Therefore, when purchasing a battery car, you need to pay special attention to terms such as mileage and service life, and clarify with the merchant. When a battery car reaches the end of its service life, you must not continue to use it with a fluke mentality, but should hand over the car and battery to a qualified organization for recycling and cascade utilization to maximize personal safety and social benefits at the same time.

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03

Understand the temper of lithium batteries

Save money and be safe

On the premise of strictly following the above points, there are also some good habits that can better maintain the health of the battery and give consumers a better product experience:

First, don’t charge for too long. Although electric vehicles will automatically shut down after being fully charged, long-term charging may still damage the battery and shorten the range.

Second, when you don’t use the battery car for a long time, try to keep the battery half-charged, because fully charging or fully discharging will cause irreversible capacity loss to the lithium-ion battery, accelerate battery aging, and affect the battery’s power and discharge energy.

Third, try not to charge in hot weather or humid environments. Try not to charge immediately after driving in high temperatures, try to ensure that there is no debris around when charging, and try to ensure good ventilation when charging.

In short, the battery safety issue of electric bicycles is by no means difficult to control. As long as you strictly abide by relevant national regulations, purchase regular products, and use them correctly according to the instructions, you can use electric bicycles with confidence in your daily life.

Author: Xu Xilin PhD student at Clean Energy Laboratory, Institute of Physics, Chinese Academy of Sciences

Review | Yu Xiqian Researcher at Clean Energy Laboratory, Institute of Physics, Chinese Academy of Sciences

Editor | Ding Zong

This article is produced by the "Science Rumor Refutation Platform" (ID: Science_Facts). Please indicate the source when reprinting.

The pictures in this article are from the copyright gallery and are not authorized for reproduction.

References:

[1] There have been 6,462 electric vehicle fires across the country this year.

[2] The search engine was Baidu, the search content was “battery vehicle explosion”, and the search time was 20:06 on September 8, 2021.

[3] Xuning Feng, Minggao Ouyang, Xiang Liu, LanguangLu, Yong Xia, Xiangming He, Thermal runaway mechanism of lithium ion battery for electric vehicles: A review, EnergyStorage Materials, 2018, 10, 246-267.

[4] Notice of the General Office of the State Administration for Market Regulation on the results of the national supervision and random inspection of the quality of 60 products including children's bicycles in 2019

[5] Report on the National Supervision and Sampling Inspection of the Quality of 8 Online Products Including Children’s and Infant Clothing

[6] 2020 National Supervision and Sampling Inspection Report on the Quality of 37 Products Including Leather Shoes

[7] Order No. 5 of the Ministry of Emergency Management of the People’s Republic of China