Driving mileage is a key factor that people consider when they buy new energy vehicles. is also the relevant departments to formulate policies of important considerations, therefore, the new energy vehicles to higher than the energy-powered lithium batteries more preference, in the three booster, high than energy-powered lithium battery gradually become mainstream.
However, the current technical conditions of high energy-powered lithium battery life decay fast, lithium battery cycle life and the life of the vehicle mileage is inconsistent, lithium battery calendar life and the whole vehicle service life is not consistent, which brings a lot of trouble for the promotion of new energy vehicles.
Why is high energy lithium battery life decay faster?
From the microscopic view, lithium battery in the use of the process, the internal will occur electrolyte decomposition, active material deactivation, negative and positive structure collapse of lithium ion embedding and the number of the drop in the irreversible electrochemical reaction and lead to capacity decline.
Especially at high voltage and high temperature, the positive surface of highly lithium-ion is very easy to react with electrolyte, for example, the reactivity of NCM811 and electrolyte in charge state is much greater than the activity of NCM111 and electrolyte reaction. Therefore, the higher the charge and discharge voltage and the higher the temperature, the faster the capacity of lithium battery decreases.
From the macroscopic point of view, how to accurately measure current, voltage and temperature, do a good job of thermal management, power management and energy management? How to perceive the life state of high specific energy power lithium battery and prolong its service life? The Battery management system is undoubtedly playing an important role.
Exploring solutions from different dimensions
As for the NCM811 Energy power lithium battery life attenuation too fast problem, the current industry solutions from materials, electrolyte, diaphragm and battery management system.
Materials, the surface of the NCM811 particles can be modified to improve its performance. Because the electrolyte additive is different, the polarization degree and the polarization speed of the battery are also different, so it is possible to improve the cycle life and safety of the high specific energy power lithium battery by using the electrolyte which can reduce the parasitic reaction inside the battery.
Application of multifunctional composite coating for ceramics and polymers, the stability and safety of high specific energy power lithium battery under high temperature and high pressure were improved. In addition, the development of silicon-carbonanode special process system and electrolyte, so that the first effect of the battery increased to 86% and above, to solve the battery first 50 weeks of rapid decay problem, Improve the battery capacity and experimental life.
At the level of battery management system, the optimal design method of battery pack based on "electric-thermal-life" coupling model is proposed, which can measure the impedance and capacity of cell monomer, and collect multiple space and time dimension data. At the same time, the design can ensure the consistency of the battery pack, and realize multiple factors and multiple physical field coupling. According to the introduction, this is based on life expectancy, prediction and management of the third generation of battery management system (the first generation of battery management system with single security monitoring as the core, the second generation of battery management system to the core of Soc), the management system has a complete series-parallel program, balanced solution and thermal management program, It can effectively manage the life attenuation of high specific energy power lithium battery.