How should the hottest domestic enterprises deal w

2022-09-27
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How should domestic enterprises deal with potential battery safety hazards

recently, Volkswagen and Korean battery supplier LG formed a special working group and will maintain a high frequency of meetings to ensure that LG can supply battery products to Volkswagen stably. Volkswagen believes that there may be potential safety hazards in battery production and battery packaging due to the use of new battery technology in the battery supply process

obviously, as a leading lithium battery supplier in the world, LG can't make the public feel completely at ease about the safety of its products, especially when new technologies are applied to products. Combined with the recent frequent car recalls, it is not difficult to find that battery safety is still a daggers sword hanging in the hearts of new energy vehicle enterprises around the world

in China, due to the late start of new energy vehicle technology and frequent policy changes, new energy vehicles have been iterating all the time. Lack of sufficient verification, security risks are more prominent

according to statistics, since 2018, there have been more than 50 domestic electric vehicle fires, large and small. Recently, the high frequency of electric vehicle fires has made battery safety the focus of the entire industry. From electric vehicle consumers to experts and scholars, national ministries and commissions have voiced their emphasis on the core position of safety in new energy vehicles

battery accident has nothing to do with the technical route

between the urgency of lithium battery safety, some experts even proposed that the development of power batteries should abandon ternary and return to the era of lithium iron phosphate. This view is actually a little too much. If you are familiar with the thermal runaway process of lithium batteries, you should understand that the safety of lithium iron phosphate batteries is only relatively speaking. If you fail to do a good job in the protection and design of overall safety, all kinds of batteries are in danger

the thermal runaway process of the cell is roughly as follows: when the cell temperature rises to a certain degree (about 130 ℃), the SEI film on the surface of the negative electrode will begin to decompose, resulting in a violent redox reaction when the highly active lithium carbon negative electrode is exposed to the electrolyte, and the generated heat makes the battery enter a high-risk state. When the local temperature inside the battery rises to more than 200 ℃, the passive film on the surface of the positive electrode decomposes, and oxygen evolution occurs on the positive electrode, which continues to react violently with the electrolyte to generate a lot of heat and form a high internal pressure. When the battery temperature reaches above 240 ℃, there is also a violent exothermic reaction between lithium carbon cathode and binder

it can be seen that in the thermal runaway of lithium batteries, the direct cause is the damage of SEI film on the surface of the negative electrode, which leads to the intense exothermic reaction between the highly active lithium embedded negative electrode and electricity, especially those products that have been in contact with body fluids or tissues for more than 24 hours, while the decomposition and exothermic reaction of the positive material is only one of the links of the thermal runaway reaction, and it is not even the main factor

therefore, the claim that lithium iron phosphate (LFP) is safer due to thermal stability is actually one-sided. The safety of lithium iron phosphate is only relatively speaking, so it is biased to judge lithium iron phosphate and ternary technology route with battery safety as an argument

a fact in front of us is that with the collapse of American A123, almost no mainstream car companies in the world adopt the technical route of lithium iron phosphate. It is not difficult to find that there are cases of fire in both iron lithium and Sanyuan by analyzing the fire of domestic electric vehicles. It is better to find the real culprit of battery safety hazards than to tangle in the technical route

design and quality control are the "behind the scenes" of battery safety.

in fact, the failure of the battery cell is only a small part of the potential safety hazards of the whole battery system. From the perspective of the module, because many factors such as the cell structure, working mode and environment will double the hidden dangers of the cell, the structural design of the power system, the control system, the tightness of production control and so on are the more important parts

not long ago, an insider analyzed three electric vehicles that had spontaneous combustion and found that the power battery suppliers and car companies involved did not pay attention to safety. In order to reduce costs, the quality control of battery cells was not strict, the BMS design requirements were too low, and the power battery pack was not adequately protected by safety design

obviously, design and quality control are the culprits causing the spontaneous combustion of these three accident vehicles, and similar cases are by no means rare. Wang Binggang, director of China Automotive Technology Research Center, said in an interview that some safety accidents of electric vehicles in China are very low-level mistakes, such as not being protected during charging, and continuing to charge after the battery is fully charged until the battery pack is bulging and on fire. Such inferior products have also passed the access test, which either indicates that the access is not strict, or that they are not produced in accordance with the requirements

Ouyang Minggao, executive vice president of the China Electric Vehicle Association, also said at the global future travel conference that the main reasons for the recent fire of new energy vehicles are product quality problems, failure to comply with technical specifications and standards, and a shorter technical verification cycle. It is embodied in three aspects: first, the testing and verification of battery products are insufficient; Second, the reliability changes during the use of vehicles; Third, there are problems in charging safety management technology

among them, charging safety is particularly important, because most safety accidents occur during charging. At this time, when the battery is connected with the charging system, it is the easiest time for the heat to get out of control. At the same time, the short circuit of high-voltage electrical appliances, etc., will easily cause accidents. (the distance between the thick wires should be longer, so that the wires have a tension of about 15-25 kg.) turn the main clip handle to clamp the lower end of the wires. Originally, the country has an iso26262 implementation specification for the battery management system, but most enterprises do not strictly implement the functional safety specification in the design

how should China face the hidden danger of battery safety

in the final analysis, the current battery safety problem lies in the battery structure design and product quality control, not the so-called technical route, and it is not an easy thing to design and quality control. Especially under the pressure of policy emphasizing energy density and market forcing cost control, it is difficult for enterprises to do well in quality with both

in this regard, Ouyang Minggao's suggestion is that it is not appropriate to forcibly implement the original industrialization plan (the monomer will reach 350 Watt hours/kg in 2020, the system will reach 260 watt hours/kg, and the cycle life will be 2000 times). At the same time, the subsidy policy should conform to the law of technological development, and the increase of energy density should not be too fast, and should not be changed too frequently. Enterprises should be given enough time to quickly improve product quality and eliminate potential safety hazards

Dong Yang, executive vice president of the China Automobile Association, also expressed a similar view. He believed that the displacement accuracy of enterprises: better than ± 1% should become the first person for the safety of electric vehicles. Power battery manufacturers, electric vehicle manufacturers, and charging operation enterprises should pay more attention to the safety of electric vehicles, and put safety in a more important position than energy density, driving range, convenient charging, etc. In addition, all enterprises should strengthen cooperation, strengthen data connectivity, and form a mechanism for cooperative analysis of accident causes and improving safety

at the government level, we should strengthen management innovation and establish a system to ensure the safety of experimental mechanical barrier electric vehicles with accuracy of 5.0.5 and 1. First, maintain the stability of technical indicators such as electric vehicle access and subsidies, and do not change technical indicators frequently. If technical indicators are changed, enterprises should be given at least two years to develop, design and verify new products. The second is to establish a safety management mechanism for electric vehicles. Once a safety accident occurs, experts should be organized to analyze and study it in time, find out the cause of the accident, and put forward technical suggestions that can be learned by the whole industry. It is strictly forbidden for enterprises to hide the report. Third, according to the characteristics of electric vehicles, establish a periodic product safety inspection system

it is worth mentioning that design and quality control can effectively curb lithium battery safety accidents, but the safety problems will eventually return to technical problems. The later the battery industry develops, the more battery safety becomes a bottleneck technology. For example, the fast charging technology of charging more than 300 kilometers in ten minutes will bring challenges to battery safety. The voltage will be increased from 300V to 600V or even 800V, which are related to safety and will also be the main battlefield of pure electric vehicle competition in the future

therefore, to solve the safety problem, in addition to working hard on product quality, comprehensively improving the safety technology of the existing lithium-ion power battery system, and making every effort to break through the new solid-state battery and other technologies are also the top priority

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