With the rapid development of new energy vehicles and energy storage systems, lithium-ion batteries, as the core technical support, have attracted much attention for their safety and life. Recently, China's scientific research team has successfully developed a significant lithium-ion battery in-situ expansion force monitoring technology, which has brought a revolutionary breakthrough to the "health" management of lithium-ion batteries, which is expected to extend the battery life by 30% and double the safety factor.
1. Key challenges for lithium-ion batteries
Although lithium-ion batteries are widely used in many fields due to their high energy density and long cycle life, they face problems such as lithium dendrite growth and SEI film growth during use, which are like the "sword of Damocles" hanging over the safety and life of the battery. Lithium dendrites are a kind of lithium metal fibrous deposits formed during the charging and discharging process of batteries, which can easily puncture the battery separator and cause short circuits inside the battery, resulting in fire, explosion and other safety accidents. According to relevant statistics, in battery failure cases, short circuit faults caused by lithium dendrites account for as much as 18%. The SEI film is formed on the surface of the negative electrode during the first charge and discharge of the battery, which can prevent the further decomposition of the electrolyte, but its thickening will increase the internal resistance of the battery, reduce the battery capacity and cycle life, and accelerate the battery capacity attenuation rate by 20%-30%.
Figure: System schematic diagram (a) Integrated ionized sensing technology implanted in the battery; (b) Structural diagram of integrated ionized sensor; (c) the pressure response mechanism of the pressure sensing unit; (d) the principle of monitoring the ionic conductivity of the electrolyte by the reference unit; (e) Eliminate the interference of environmental factors on the pressure sensing unit by compensation algorithms
2. The dilemma of traditional monitoring techniques
In order to monitor the internal state of the battery, the traditional implantable fiber monitoring method has obvious limitations. On the one hand, its system size is large, which is difficult to adapt to the development trend of battery miniaturization and integration; On the other hand, the mechanical properties of optical fibers are fragile and easily damaged in the complex internal environment of the battery, resulting in interruption or distortion of monitoring data. Although the flexible pressure sensor has certain advantages, it is difficult to guarantee long-term stability in the face of corrosive electrolyte environment, and the performance is usually greatly reduced after working in the battery electrolyte environment for several hours to several days, which cannot meet the needs of long-term stable monitoring of the battery, and these difficulties seriously restrict the development of battery monitoring technology.
3. Innovative breakthroughs in China's new monitoring technology
The integrated ionized sensing technology developed by China's scientific research team has brought dawn to the industry. This technology cleverly uses the electrolyte and materials of lithium-ion batteries to build a sensing interface, eliminating the need for additional packaging, and achieving high-precision pressure monitoring. It is highly compatible with battery materials and effectively solves the stability challenges of traditional flexible pressure sensors in corrosive environments. Experimental data show that the integrated ionization sensing technology is sensitive to changes in Pa-level expansion force and can work stably in the battery for more than one month. Through the accelerated aging experiment of 400 cycles of charge-discharge cycle, the technology accurately captures the irreversible deposition of lithium dendrites and the pressure accumulation caused by the thickening of the SEI layer and the growth of lithium dendrites, and finds that the pressure change is highly consistent with the capacity decay trend, with a correlation coefficient of more than 0.95, which verifies the accuracy and reliability of its monitoring.
4. The new technology has significantly improved battery life and safety
Based on experiments and data analysis, this new technology can increase battery life by up to 30%. In practice, this means that the battery replacement cycle of electric vehicles is expected to be extended from the current 8-10 years to 10-13 years, greatly reducing the cost of use for consumers and after-sales costs for manufacturers. At the same time, the safety factor has been doubled, which is mainly reflected in the ability to warn in advance of potential safety hazards such as lithium dendrite growth. By monitoring the changes in the expansion force in real time, once an abnormality is detected, timely measures can be taken, such as adjusting the charging strategy and limiting the discharge depth, etc., to reduce the incidence of safety accidents by more than 50%.
5. Prospects for industrial application of new technologies
For the new energy vehicle industry, the promotion and application of this technology will promote the upgrading of the battery management system, improve the safety and reliability of the whole vehicle, and enhance the market competitiveness of the product. It is estimated that if the new technology is widely used in the field of electric vehicles, the global electric vehicle battery failure rate can be reduced by 15%-20%, saving car companies more than $10 billion in after-sales maintenance costs every year. In the field of energy storage systems, it can ensure the safe and stable operation of large-scale energy storage power stations, reduce operation and maintenance costs, and with the expansion of the energy storage market, it is expected to create more than 50 billion US dollars of economic benefits for the energy storage industry by 2030.
6. Conclusion
The in-situ expansion monitoring technology of lithium-ion batteries developed by China's scientific research team has successfully broken through the bottleneck of traditional monitoring technology and provided a strong guarantee for the efficient and safe use of lithium-ion batteries. Its significant advantages of extending the "life" of the battery by 30% and doubling the safety factor will surely trigger far-reaching changes in the fields of new energy vehicles and energy storage systems, and promote the global new energy industry to a new height, fully demonstrating China's strong strength and responsibility in the field of research and development of key core technologies of new energy, and contributing to the realization of the goal of carbon peak and carbon neutrality.
