Driving mileage is a key indicator that people consider when purchasing new energy vehicles. It is also an important consideration for the relevant departments to formulate policies. Therefore, new energy vehicles are more preferred for high-energy- power lithium batteries . Under the push, high-energy-powered lithium batteries are becoming mainstream.

However, the current high technologies to the decay faster than energy power lithium battery life, is inconsistent with the vehicle mileage life cycle life of lithium batteries, lithium battery life and calendar life of the vehicle inconsistent, which gives the promotion of new energy vehicles brought A lot of troubles.

Why does the high specific energy lithium battery life decay faster?

From the micro-viewing, during the use of the lithium battery, an internal irreversible electrochemical reaction such as decomposition of the electrolyte, deactivation of the active material, collapse of the positive and negative structures, and reduction in the number of lithium ion insertion and deintercalation may occur, resulting in a decrease in capacity.

Especially under high voltage and high temperature conditions, the highly delithiated positive electrode surface easily reacts with the electrolyte. For example, the activity of NCM811 in the charged state reacts with the electrolyte much more than the reaction of NCM111 with the electrolyte. Therefore, the higher the charge and discharge voltage and the higher the temperature, the faster the lithium battery capacity decreases.

From a macro perspective, how to accurately measure current, voltage and temperature, do thermal management, power management and energy management? How to perceive the life status of high specific energy lithium battery and extend its service life? There is no doubt that the battery management system plays an important role. Character.

Explore solutions from different dimensions

Regarding the problem that the lifetime of the NCM811 is higher than that of the energy-powered lithium battery, the current solutions in the industry start from materials, electrolytes, diaphragms and battery management systems.

In terms of materials, the surface of the particles of NCM811 can be modified to improve its performance. Due to the difference in electrolyte additives, the polarization degree and polarization speed of the battery are also different. Therefore, the cycle life and safety of the high specific energy power lithium battery can be improved by using an electrolyte capable of reducing the internal parasitic reaction of the battery.

Penghui Energy has improved the stability and safety of high specific energy lithium battery under high temperature and high pressure through the application of ceramic and polymer multifunctional composite coating. In addition, Penghui Energy has developed a special silicon carbon negative electrode. The process system and electrolyte improve the battery's first effect to 86% and above, solving the problem of rapid decay in the first 50 weeks of the battery, and improving the battery capacity and experimental life.

At the level of battery management system, Professor Wei Xuezhe, deputy dean of Tongji University Automotive College, proposed a battery pack optimization design method based on the “electric-thermal-life” coupling model, which can measure the capacitance of the battery cells, estimate the capacity, and collect multiple spaces. Time dimension data. At the same time, the design can ensure the consistency of the battery pack and achieve multi-factor and multi-physics coupling. According to Professor Wei Xuezhe, this is the third generation battery management system with life estimation, forecasting and management as the core (the first generation battery management system is based on single security monitoring, and the second generation battery management system is based on SOC estimation). The management system has a complete series-parallel scheme, equalization scheme and thermal management scheme, which can effectively manage the life decay of the high specific energy power lithium battery.