Content Summary
Welcome to a new year and a new semester! The ShanghaiTech EHS WeChat account is excited to launch a brand new column in our Laboratory Safety series #YouAskIAnswer#. Here, you can ask questions about all aspects of laboratory safety, and we will invite professors and experts to provide answers.
This Issue's Guest
Wang Haoyu
Associate Professor, Researcher, PhD Supervisor
School of Information Science and Technology, ShanghaiTech University
Hot Questions
Question 1
How should spent button lithium batteries be disposed of in the laboratory?
— Shang Rongliang, School of Materials Science
Answer
Lithium-ion batteries are used in a wide range of applications, from mobile phones and e-bikes to electric vehicles and energy storage stations. Spent button lithium batteries are also widely used in various stationery products. Toxic and harmful substances in spent lithium batteries can cause serious pollution to the soil, water, and atmosphere once they leak; moreover, spent lithium-ion batteries are often referred to as abandoned resource banks. Not only lithium but also many valuable metals such as cobalt and nickel can be recycled. In response to the national policy of environmental protection and resource conservation, spent lithium-ion batteries should be collected and processed in a centralized and unified manner.
Please store the batteries in a cool and dry place, and do not mix them with metal objects to prevent metal from touching the battery terminals, causing a short circuit, damaging the battery, or even posing a danger. Do not knock, puncture, step on, modify, or expose the battery to the sun, and do not place the battery in environments like microwaves or high voltage. If a lithium-ion battery has been submerged or soaked in water, short-circuiting during charging or discharging may cause fire or explosion risks. If soaked, place the battery in an open area and do not bring it indoors. Be mindful to avoid the battery getting wet to prevent dangers.
If any spent lithium-ion batteries in the laboratory exhibit swelling, leakage, or similar issues, please contact the transportation and disposal department promptly. If there is a need to recycle spent lithium-ion batteries in the laboratory, please contact the EHS department.
Question 2
What are the main reasons for failures in new energy lithium-ion batteries?
Answer
a) Mechanical Abuse: Generally caused by mechanical deformation of the battery due to physical stress, specifically from vehicle collisions and subsequent compression, puncturing, etc. This leads to short-circuiting of the positive and negative terminals, releasing a large amount of heat and causing thermal runaway.
b) Electrical Abuse: Typically involves overcharging and over-discharging under normal use conditions. Both types of electrical abuse can damage the structure of the battery's electrodes, leading to internal short circuits and subsequent thermal runaway.
c) Thermal Electrical Abuse: Improper temperature management resulting in the battery overheating, which can lead to fires or explosions.
Question 3
What are the safety precautions for using lithium-ion batteries?
Answer
a) Do not use second-hand or unbranded lithium batteries: Second-hand batteries are likely to be in poor health and prone to internal short circuits.
b) Try to prevent e-bikes from getting rained on: Since the batteries of electric bicycles are exposed, if they get wet, the battery case will gradually corrode due to electrochemical reactions. Once the casing corrodes enough to expose the electrodes, the electrodes meeting water will generate a violent chemical reaction, eventually igniting the entire battery pack.
c) Strictly prohibit indoor charging: If an electric vehicle catches fire, it burns very quickly and produces a large amount of toxic smoke. If it happens in a confined space, especially in places like laboratories, homes, or elevators, inhaling toxic dense smoke can cause great harm to people and is very likely to lead to casualties. This is why charging electric vehicles indoors is not allowed.
Question 4
How should a lithium-ion battery fire be extinguished?
Answer
It is not recommended to use a dry powder fire extinguisher for lithium-ion battery fires. Although a dry powder extinguisher can extinguish the flames initially, it cannot lower the internal temperature of the battery, so the internal chemical reactions continue, potentially leading to re-ignition. It is also not recommended to use Class D extinguishers. Water-based extinguishers or water can be used to extinguish the fire and control the spread of the flames. Class D extinguishers are suitable for fires caused by combustible metals (such as aluminum, titanium, magnesium, lithium, zirconium, sodium, and potassium).
Image and text source: Public Account Power Electronics Laboratory
