Recently, the news that an electric vehicle in a small area of Nanjing caused a fire, resulting in 15 deaths and 44 injuries, has aroused everyone's attention.
As a common means of transportation, electric vehicles have gradually become one of the important "vehicles" for urban travel due to their advantages of energy saving, environmental protection and lightness. In daily life, we can often see parked electric vehicles in the door of the unit, in the corridor aisle, and also see someone at home, or from the home to connect the wire for "flying" charging, and these behaviors are more or less safety hazards.
Why do electric vehicles use lithium batteries?
And how is the battery**?
The power batteries that are usually suitable for electric vehicles can be divided into two categories: lithium batteries and lead-acid batteries. Lithium batteries have become the preferred power supply for electric vehicles because of their high power density, light weight, and environmental friendliness.
According to the statistics of the China Electronics Industry Standardization Technology Association (CESA), lithium batteries accounted for 97% of China's new electrochemical energy storage installed capacity in 20201%, which has a certain advantage in the market. The most important factors that cause lithium batteries are overcharge and short circuit.
An electric car in the stairwell that was being charged suddenly spontaneously combusted, and it happened 3 times in just 15 seconds!
Overcharging, which mainly occurs during the charging process of lithium batteries, will accumulate a lot of heat during the charging process due to the resistance of the battery. The protection device in the lithium battery can protect the overcharge to a certain extent by detecting the voltage.
However, when the overcharge time is too long and the voltage continues to be too high, the dendrite short circuit inside the lithium-ion battery is prone to occur, resulting in the continuous rise of the temperature and pressure of the lithium battery, resulting in the risk of high quality.
Short circuit mainly occurs during the use of lithium batteries, when the lithium battery is used, its own temperature will continue to rise, and the battery will also maintain normal heat dissipation.
If the battery temperature is too high due to external factors, it is easy to cause damage to the battery separator and cause a short circuit, resulting in excessive internal heat accumulation, triggering a chain chemical reaction, and causing the battery to burn.
In addition, the mixing of charging equipment for different brands of electric vehicles will also cause damage to the battery.
The reporter learned from relevant departments that at present, many places, including Beijing, have formulated local technical standards for the safety of lithium-ion batteries for electric bicycles; In addition, China's mandatory national standards are about to be introduced.
In order to prevent the occurrence of quality and safety accidents of electric bicycles from the source, in 2022, the Beijing Bicycle and Electric Vehicle Industry Association formulated the group standard "Technical Specifications for Lithium-ion Power Battery Packs for Electric Bicycles".
You Tao, Director of the Product Quality and Safety Supervision and Management Department of the Beijing Municipal Administration for Market Regulation: 33 safety technical indicators such as overcharge, overdischarge, battery pack temperature protection and overcharge protection of single batteries have been stipulated.
The reporter inquired in the official ** of the Standardization Administration of the People's Republic of China that the mandatory national standard "Safety Technical Specifications for Lithium-ion Batteries for Electric Bicycles" drafted by the Ministry of Industry and Information Technology in 2022 has completed the drafting and solicitation of opinions, and is currently in the review stage. He Penglin, deputy director of the Safety Technology Research Center of the China Electronics Standardization Institute, is the head of the Ministry of Industry and Information Technology's lithium-ion battery and similar product standards working group, and one of the main drafters of this national standard.
He Penglin, Deputy Director of the Safety Technology Research Center of China Electronics Standardization Institute: According to the project plan, this mandatory national standard will be released this year. This standard will fill the gap in the technical basis for the safety and quality supervision of lithium-ion batteries for electric bicycles at the national level. After the standard is issued, in accordance with the provisions of the Standardization Law of the People's Republic of China, products and services that do not meet the mandatory standards shall not be produced, sold, imported or provided.
*: CCTV Finance and Economics, Science Refutes Rumors.