In recent years, driven by the booming development of the new energy vehicle market, the installed capacity of domestic power lithium battery systems has increased rapidly. In the first five months of this year, the installed capacity of domestic power lithium batteries reached 41.4 gigawatt-hours, a cumulative increase of 223.9% year-on-year.
With the popularization of new energy vehicles, the frequent occurrence of spontaneous combustion of cars is constantly impacting consumers' fragile nerves, and battery safety and range issues have also become the focus of electric vehicle discussions.
Data from relevant laboratories at Beijing Institute of Technology shows that, when categorizing fires in new energy vehicles according to their causes, fires caused by faulty power lithium batteries account for about one-third of all such incidents.
In response, Wei Zhongbao, a professor at Beijing Institute of Technology, stated, "This scale is still very large, and it also reflects the fact that power lithium battery technology is a key technology restricting the further popularization of new energy vehicles."
Furthermore, if classified according to the state of the vehicle at the time of the accident, it can be found that the proportion of fires occurring when the vehicle is charging accounts for 28%, while the proportion of fires occurring when the vehicle is stationary has been rising year by year to 38%.
"Fires occurring while charging are primarily related to the charging station, including its control strategy and system-vehicle mismatch. Currently, there is no unified consensus in the industry regarding fires occurring while the battery is stationary. We infer that damage caused by lithium absorption in the power lithium battery during long-term service is certainly a significant contributing factor," said Wei Zhongbao.
On the other hand, he believes that imperfections and inaccuracies in the monitoring and protection strategies for power lithium batteries can also lead to accidents in power lithium battery systems when the battery is idle.
It is understood that Beijing Institute of Technology has the only new energy vehicle operation monitoring platform in the country. As of July 2, the platform has monitored more than 5 million vehicles.
Wei Zhongbao believes that the immaturity of the technology is related to the relatively short history of industrial development. In 2001, with the national "15th Five-Year Plan" identifying electric vehicles as a priority, research projects on on-board lithium-ion batteries for vehicles were gradually launched. However, it wasn't until January 2009, when multiple government departments jointly launched the "Ten Cities, Thousand Vehicles Energy-Saving and New Energy Vehicle Demonstration and Promotion Application Project," that my country's automotive industry began its electrification transformation, and lithium-ion batteries, as a core component of new energy vehicles, started to receive widespread market attention.
With the support of national financial subsidies, China's power lithium battery industry has entered a phase of large-scale research and development. Therefore, the development history of the power lithium battery industry is relatively short.
To address this issue, Wei Zhongbao proposed that in order to achieve an overall improvement in battery safety performance and prevent more fire accidents, we need to tackle this problem together from three aspects: high-quality battery cells, high-quality battery pack technology, and a high-level management system.
Specifically, this involves improving, optimizing, controlling, and managing five key aspects: critical materials, cell design, cell manufacturing/process factors, system integration, and actual use.
Beyond safety concerns, the industry pain point of a sharp decline in the range of new energy vehicles in low-temperature environments has also made many consumers in northern China hesitant to purchase new energy vehicles.
To address range anxiety in the market regarding new energy vehicles, more and more automakers are using long range as a selling point, continuously launching vehicles with longer driving ranges. For example, the NIO ET7 will be equipped with a 150kWh solid-state battery, with a maximum range of over 1,000 kilometers; Zhiji Auto will be equipped with a battery jointly developed by SAIC and CATL, which is the first to adopt "silicon-doped lithium-ion" technology, with a single cell energy density of 300Wh/kg and a maximum range of over 1,000 kilometers.
The continuous pursuit of longer driving range will lead to vehicles carrying more and more batteries, which will put greater pressure on automakers to reduce emissions.
"When we launched the national major project (developing new energy vehicles) 20 years ago, we considered the pressure of oil imports and discussed energy security, energy conservation and emission reduction," said Wang Zidong, deputy secretary-general of the my country Automotive Power Lithium Battery Industry Innovation Alliance. He added that some car companies have now deviated from their original intention of energy conservation and emission reduction and are all focusing on increasing driving range.
Professor Zhang Lei from Beijing Institute of Technology, speaking from a problem-solving perspective, stated that batteries are difficult to maintain and need to operate in a relatively comfortable state. However, due to significant regional differences in my country, the BMS (Battery Management System) needs to have reliable thermal management to ensure that the battery can operate within a relatively comfortable temperature range, thereby maximizing its performance.
It is understood that battery thermal management has two main aspects: heating and cooling. Common cooling methods in China are air cooling and liquid cooling, with liquid cooling currently being the mainstream approach. As for heating, early solutions involved adding a heating plate to the battery pack, and later heating films were developed, but these methods have consistently proven ineffective in stabilizing vehicle range.
In response, Zhang Lei stated, "Our team is currently working on all-weather batteries and is pushing them towards industrialization. They will be used at the Beijing Winter Olympics and will solve the problem of battery applications in low-temperature conditions."
In November 2020, the General Office of the State Council released the "Development Plan for the New Energy Vehicle Industry (2021-2035)," which proposed that by 2025, new energy vehicle sales should account for 20% of total vehicle sales that year; and by 2035, pure electric vehicles should become the mainstream of newly sold vehicles. Experts emphasize that in the foreseeable future, battery safety and range will continue to be the two major focal points for new energy vehicles.
