Exploring The Battery Secrets of Xiaomi SU7 Ultra And Analyzing The Function of Glove Box

On the evening of February 27, 2025, Xiaomi released the SU7 Ultra.

On March 2, 2025, Lei Jun, founder, chairman, and CEO of Xiaomi, posted on Weibo that within less than three days of its release, the Xiaomi SU7 Ultra had a large order quantity of 19000 units and locked in over 10000 units, completing the annual target ahead of schedule.

The Xiaomi SU7 Ultra uses CATL Kirin II track battery, which is a ternary lithium battery. From the perspective of energy density, ternary lithium batteries typically have an energy density between 180 and 230 Wh/kg, which is higher than lithium iron phosphate batteries and can provide vehicles with longer range.

In low-temperature environments, the discharge performance of ternary lithium batteries is much better than that of lithium iron phosphate, which can effectively reduce the problem of vehicle power failure in low-temperature areas and ensure stable vehicle performance. The ternary lithium battery is lightweight and small in size, which helps reduce the weight of the vehicle and allows it to run faster.

The stability of materials is crucial in the development process of ternary lithium batteries. The positive and negative electrode materials of ternary lithium batteries are extremely sensitive to moisture and oxygen. Moisture can cause hydrolysis of lithium salts, reducing battery performance; Oxygen may cause material oxidation, affecting the charging and discharging efficiency and cycle life of batteries.

The glove box can effectively remove oxygen and moisture from the gas by filling it with high-purity inert gas (such as nitrogen or argon) and continuously circulating and filtering, creating a stable inert atmosphere environment and providing pure reaction conditions for the synthesis of battery materials and electrode preparation. The water and oxygen content in the lithium battery glove box can be controlled below 1ppm. This anhydrous and oxygen free environment can prevent lithium salt hydrolysis and material oxidation, thereby ensuring the stability and consistency of ternary lithium battery materials and helping to develop better performance ternary lithium batteries.

The purity of battery materials has a significant impact on battery performance. The seemingly calm air is actually suspended with a large amount of dust, particles, and other impurities that are difficult to detect with the naked eye. When these dust and particles enter the interior of the battery, during the charging and discharging process, they may puncture the separator inside the battery, causing direct contact between the positive and negative electrodes, thereby triggering a short circuit inside the battery, instantly releasing a large amount of energy, and causing the battery to overheat or even catch fire.

The sealing design and filtration system of the glove box can effectively prevent external impurities from entering and filter impurities in the gas inside the box, ensuring high purity of the atmosphere inside the box.

The clean environment inside the glove box during electrode coating, material mixing, and other operations helps improve the consistency and yield of the battery. In electrode coating, researchers need to evenly coat the slurry containing active materials on the electrode substrate to form a thin layer of electrode coating. In this process, any tiny dust or particles mixed into the slurry may cause uneven coating, affecting the conductivity of the electrode and the distribution of active substances. However, in a glove box with a high clean atmosphere, the slurry can maintain high purity, thereby preparing electrodes with stable and consistent performance and improving the quality of ternary lithium batteries.