r03 battery

r03 battery accidents have nothing to do with technical routes

Due to the urgency of lithium r03 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 bit 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 relative. If the overall safety protection and design are not done well, all kinds of batteries are facing danger.

The thermal runaway process of the r03 battery cell is roughly as follows: When the temperature of the r03 battery cell rises to a certain level (about 130°C), the SEI film on the surface of the negative electrode will begin to decompose, causing the highly active lithium-carbon negative electrode to be exposed to the electrolyte and undergo a violent redox reaction. The heat generated puts the r03 battery into a high-risk state. When the local temperature inside the r03 battery rises to above 200°C, the passivation film on the surface of the positive electrode decomposes the positive electrode to produce oxygen, and continues to react violently with the electrolyte to generate a large amount of heat and form a high internal pressure. When the r03 battery temperature reaches above 240°C, it is also accompanied by a violent exothermic reaction between the lithium-carbon negative electrode and the binder.

It can be seen that in the thermal runaway of lithium batteries, the direct cause is the damage of the SEI film on the surface of the negative electrode, which leads to a violent exothermic reaction between the highly active lithium-embedded negative electrode and the electrolyte, while the decomposition and exothermic release of the positive electrode material is only one link in the thermal runaway reaction, and it is not even the main factor.

Therefore, the so-called statement that lithium iron phosphate (LFP) is safer because of its thermal stability is actually very one-sided. The safety of lithium iron phosphate is only relative, so it is biased to use r03 battery safety as an argument to judge lithium iron phosphate and ternary technology routes.

A fact in front of us is that with the collapse of A123 in the United States, almost no mainstream car companies in the world adopt the technology route of lithium iron phosphate. It is not difficult to find out from the analysis of domestic electric vehicle fires that there are cases of fire and combustion, whether it is lithium iron or ternary. Instead of entangled in the technical route, it is better to find the real culprit of r03 battery safety hazards.

Design and quality control are the "black hands" behind r03 battery safety

In fact, the failure of the r03 battery cell is only a small part of the safety hazards of the entire r03 battery system. From the perspective of the module, the safety hazards of the r03 battery cell will be doubly reflected due to factors such as the r03 battery cell structure, working mode and environment. Therefore, the structural design of the power system, the control system, the strictness of production control, etc. are more important parts.

Not long ago, an industry insider disassembled three electric vehicles that caught fire and found that the power r03 battery suppliers and car companies involved did not pay attention to safety. In order to reduce costs, they did not strictly control the quality of the r03 battery cells, the BMS design requirements were too low, and there was no sufficient safety design protection for the power r03 battery pack.

Obviously, design and quality control are the culprits that caused the spontaneous combustion of these three accident vehicles, and similar cases are by no means rare. Wang Binggang, director of the China Automotive Technology Research Center, said in an interview that some of the safety accidents that occurred in electric vehicles in my country were very low-level mistakes, such as no protection during charging, and continued charging after the r03 battery was fully charged until the r03 battery pack bulged and caught fire. Such inferior products also passed the access inspection, which either means that the access was not strict or that the production was not in accordance with the requirements.

Ouyang Minggao, executive vice president of the China Electric Vehicle Hundred People's Association, also said at the Global Future Mobility Conference that the main reason for the recent fires in new energy vehicles is product quality problems, failure to comply with technical specifications and technical standards, and a short technical verification cycle. It is specifically reflected in three aspects: first, insufficient testing and verification of r03 battery products; second, changes in reliability during vehicle use; and third, problems with charging safety management technology.

Among them, charging safety is particularly important, because most safety accidents occur during charging, when the r03 battery is connected to the charging system, which is the easiest time for thermal runaway. At the same time, there are short circuits of high-voltage electrical appliances, etc., which can easily cause accidents. Originally, the country had an ISO26262 implementation specification for r03 battery management systems, but most companies did not strictly implement functional safety specifications during design.

How should China deal with r03 battery safety hazards?

In the final analysis, the current r03 battery safety problem still lies in r03 battery structure design and product quality control, rather than the so-called technical route, and it is not an easy task to combine design and quality control. Especially under the squeeze of policies emphasizing energy density and the market forcing cost control, it is difficult for companies to do a good job of quality while taking both into account.

In this regard, Ouyang Minggao suggested that it is not appropriate to force the original industrialization plan (350 watt-hours/kg for single unit, 260 watt-hours/kg for system, and 2,000 cycles in 2020). At the same time, the subsidy policy should comply with the law of technological development, and the energy density should not be increased too quickly or changed too frequently. Sufficient time should be given to enterprises to quickly improve product quality and eliminate safety hazards.

Dong Yang, executive vice president of the China Association of Automobile Manufacturers, also expressed a similar view. He believes that enterprises should be the first responsible person for the safety of electric vehicles. Power r03 battery manufacturers, electric vehicle manufacturers, and charging operators should pay more attention to the safety of electric vehicles and put safety in a more important position than energy density, driving range, and charging convenience. In addition, all enterprises should strengthen cooperation, strengthen data connectivity, and form a mechanism for cooperative analysis of accident causes and improvement of safety.

At the government level, management innovation should be strengthened and a system should be established to ensure the safety of electric vehicles. 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. Second, establish an electric vehicle safety management mechanism. Once a safety accident occurs, experts should be organized to analyze and study in a timely manner to find out the cause of the accident, and put forward technical suggestions for the whole industry to learn lessons. It is strictly forbidden for enterprises to conceal the report. Third, establish a periodic product safety inspection system based on the characteristics of electric vehicles.

It is worth mentioning that design and quality control can effectively curb lithium r03 battery safety accidents, but safety issues will eventually return to technical issues. The later the r03 battery industry develops, the more r03 battery safety becomes a bottleneck technology. For example, fast charging technology that charges more than 300 kilometers in ten minutes will bring challenges to r03 battery safety. The voltage is increased from 300V to 600V or even 800V. These are all related to safety and are also the main battlefield for 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 existing lithium-ion power r03 battery systems, and making every effort to break through new solid-state r03 battery and other technologies are also top priorities.

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