Expert: The viewpoint of "highly toxic, short-lived and easy to explode" of network-transmitted lithium battery is too one-sided.
The widely circulated online articles also questioned lithium batteries, including: lithium batteries are highly toxic, short-lived, explosive and harsh in use conditions; Unable to recycle, resulting in great environmental pressure … … Is this really the case? The "Verification" column of People’s Daily continued to interview many industry experts to explore the truth.
Lithium batteries are highly toxic and dangerous goods?
Response: Lithium batteries do not contain toxic substances, and the impact is far less than that of lead-acid batteries.
"Strictly speaking, lithium-ion batteries and lithium batteries are still conceptually different." Wang Fang, chief expert in the field of power batteries in China Automotive Technology Research Center, secretary-general and senior engineer of battery testing and application technology alliance, said that lithium batteries usually refer to batteries with lithium metal or lithium alloy as the negative electrode and non-aqueous electrolyte. Lithium-ion battery refers to rechargeable secondary battery, the negative electrode does not use metal lithium, and it works by lithium ion moving between the positive and negative electrodes. However, in daily life, people are used to calling lithium-ion batteries lithium batteries or lithium batteries for short.
It is understood that most of the new energy vehicles promoted in China (including pure electric vehicles and plug-in hybrid vehicles) use lithium-ion batteries, of which Ferrous lithium phosphate accounts for 80%— 90%, ternary lithium batteries have also been widely used in passenger cars.
In response to the statement that lithium batteries are "highly toxic dangerous goods" pointed out in the online article, Wang Fang refuted that lithium batteries do not produce any toxic and harmful heavy metal elements and substances such as lead acid, nickel chromium and nickel hydrogen, and are relatively less polluted. And its electrolyte is organic solvent and lithium salt, mostly non-toxic or low-toxic; However, the decomposition or hydrolysis products of lithium batteries are hydrofluoric acid and other fluorine-containing compounds, which are corrosive and toxic.
Liu Haojie, a researcher-level senior engineer at the 18th Research Institute of China Electronics Technology Group, said that the lithium-ion battery itself does not contain toxic substances, and the carbon in the negative electrode and the metal oxide in the positive electrode are basically non-toxic. Because lithium-ion batteries belong to a sealed system, they will not be exposed to these substances in normal use. "In any case, its impact is far less than that of the most widely used lead-acid battery at present."
Lithium batteries have short life and harsh conditions?
Response: The life of power lithium-ion battery can reach 2000 cycles, and the battery management system can limit "overcharge and overdischarge".
How long is the current lithium battery life? Will shallow charging and discharging and overcharge and overdischarge affect the safety and life of the battery?
"There are many factors that determine the service life of power lithium-ion batteries, including the characteristics of the system itself, as well as the manufacturing process and working conditions. A high-quality battery system and scientific system management can achieve a long service life. " Wang Fang said that according to the cut-off condition that the capacity decays to 80% and the discharge depth test of 100%, the life of power batteries can basically reach 2000 cycles.
"Overcharging and overdischarge means that the voltage of the battery exceeds or falls below the specified cut-off voltage during charging and discharging, which will bring harm to the performance and life of the battery." Wang Fang said, but the BMS battery management system in the battery will limit and protect it. It will limit the charging of the battery at low temperature and recharge it when it is heated to a suitable temperature. Wang Fang said that in order to ensure the safety of lithium-ion batteries, there are a series of safety protection designs from battery cells, modules to battery systems to prevent the batteries from being overcharged and over-cooled, and alarm and protect them in time in case of abnormality.
It is mentioned in the net that there have been media reports that "Tianjin No.18 Institute has proved that lithium batteries burn and explode in almost all projects such as high temperature and high pressure, puncture and impact, and overcharge and overdischarge".
In this regard, Liu Yanlong, secretary general of China Chemical and Physical Power Industry Association, said that at the end of May 2014, the 18th Research Institute of China Electronics Technology Group was interviewed by the media, but the phenomenon of battery burning and explosion in the program was caused by dismantling the protection circuit according to the requirements of program recording, and then conducting abuse experiments. The main purpose of this experiment is to let users know about the possible dangerous situation of ternary lithium battery without protective measures under abuse conditions.
"The safety of lithium-ion batteries is theoretically controllable, and most of the safety problems are caused by product defects and abuse." Liu Yanlong said. "But the safety of battery cells, modules and systems alone is not enough to ensure the absolute safety of electric vehicles equipped with lithium batteries." Li Ping, Chairman of Contemporary Amperex Technology Co., Limited New Energy Technology Co., Ltd. (CATL), introduced the current top Model— S used 7104 Panasonic ternary lithium batteries, and made great efforts in battery safety protection, including setting sensors, being controlled by battery control system, and using a large number of high-strength aluminum alloys and other materials for collision protection. With these safety designs, the probability of safety accidents still reaches one in ten thousand.
Wang Qinghua, a researcher-level senior engineer at the 18th Research Institute of China Electronics Technology Group, also pointed out that the products in the electric vehicle battery market are mixed, and the batteries produced by some manufacturers have poor consistency, and the effectiveness of the management system is not very effective. The problem of a single battery will have a certain impact on the overall life of the battery pack. In this regard, Wang Qinghua suggested that the government should improve the corresponding test and verification standards and strengthen the management, supervision and testing of the electric vehicle market.
Is the pollution of waste lithium batteries uncontrollable?
Response: Due to relatively small environmental risks, lithium batteries have not been included in hazardous waste management, but the recycling system should be laid out as soon as possible.
Is there a compulsory recycling policy for lithium batteries at present? Is it true that waste lithium batteries will cause great environmental pressure, as stated in the online article? Wang Fang said that at this stage, waste batteries that are included in hazardous waste management by environmental protection departments include waste cadmium-nickel batteries and waste lead-acid batteries. Disposable batteries, lithium-ion batteries, nickel-hydrogen batteries, etc. are not included in hazardous waste management because of their relatively small environmental risks.
However, when waste lithium-ion batteries enter the environment, the electrode materials and electrolyte react with other substances in the environment, such as hydrolysis and oxidation, which may cause heavy metal ion pollution such as nickel, cobalt and manganese, fluorine pollution and some organic pollution. So, can these pollutions be controlled?
Wang Fang said that for the treatment of lithium-ion batteries, the "Recycling Policy for Power Batteries of Electric Vehicles (2015 Edition)" drafted by the Environmental Protection Department of the National Development and Reform Commission stipulates that wet smelting technology is encouraged to treat waste lithium-ion batteries, and the comprehensive recovery rate of nickel, cobalt and manganese should be no less than 98%. "For the processing technology of lithium-ion batteries, China has always had research teams from universities and conducted cooperation and exchanges with the United States." Wang Fang said.
On January 8th, the Ministry of Industry and Information Technology issued the Interim Measures for the Administration of Industry Standard Announcement on the Comprehensive Utilization of Waste Power Batteries of New Energy Vehicles (Draft for Comment), which intends to implement dynamic management of enterprises for the comprehensive utilization of waste power batteries of new energy vehicles, and entrust relevant professional organizations to assist in the relevant work of announcement management.
Hu Shuqing, chief expert and researcher-level senior engineer of China Electronics Science and Technology Corporation, said that for lithium-ion batteries with Ferrous lithium phosphate, lithium manganate and ternary materials with low cobalt content as positive active materials, due to the low commercial value of recycling, enterprises are not interested. The recycling of these used batteries must be issued by the state policy, in order to successfully realize the closed loop of the industry. At present, China has issued some policies and standards, such as the classification of used batteries, storage and transportation norms, and technical policies for pollution prevention and control of solid waste and hazardous waste, but they are not sufficient.
"The work of recycling lithium-ion batteries should be laid out as soon as possible." Wang Binggang, head of the National 863 Energy-saving and New Energy Vehicle Project Supervision and Consulting Expert Group, said that to establish a power battery recycling system, it is necessary to improve battery standardization, establish a code traceability system, implement strict reward and punishment measures, and conduct qualification management for recycling enterprises.
(Reporter Wang Zheng Zhu Hong)