Zeng Xuezhong, vice president of Xiaomi Group and president of the mobile phone department, explained the breakthrough in the application of graphene in battery technology.
The Xiaomi Mi 10 Extreme Edition has a built-in 4500mAh battery and supports 120W wired charging. Under high-power charging, the capacity retention rate of the Mi 10 Extreme Edition battery after 800 cycles of charging and discharging is ≥90%, which exceeds the national recommended battery life standard.
When talking about the application of graphene in battery technology, Zeng Xuezhong pointed out:
In the design scheme, after exploring in multiple directions, they found that the application of graphene in lithium-ion battery cathode materials has great benefits, especially its two-dimensional lamellar structure can achieve "surface contact" with the active material, which can construct the entire electrode The "long-range conductivity" on the graphene, and graphene electrons are highly delocalized, forming a better band structure, and the conductivity is as high as >10°S/m graphene powder.
However, traditional conductive carbon black can only achieve "point contact", and a larger content is needed to form continuous electron transmission. Therefore, graphene has a lower conductivity threshold, and using a smaller amount can greatly reduce the ohmic impedance of the battery and improve the charging capacity.
The continuous and flexible sheet structure of graphene can provide continuous conduction. During the cycle of charging and discharging, the conductive contact will not be gradually lost due to the volume change of the active material. At the same time, the better thermal conductivity of graphene promotes particles The balance of temperature between the active particles avoids the life degradation caused by local overheating of the active particles, which greatly contributes to the improvement of the cycle life of high-power batteries.
Realizing the mass production of graphene-based lithium-ion battery technology also has great technical challenges. We must overcome several major technical difficulties. Among them, the most difficult and the largest R&D investment is the selection of graphene, including the preparation of graphene. The basic material characteristics and lithium-ion battery fast charging system compatibility debugging, transportation and storage conditions and other problems are overcome.
In the lithium-ion battery system, the exploration of formula design, design window, the dispersion process of graphene in active materials and the promotion of mass production process are also difficult.
The graphene-based lithium-ion battery finally successfully landed on the Xiaomi Mi 10 Extreme Edition, which greatly assisted the 120W fast charging technology.
The breakthrough in the application of graphene will bring great changes to our lives. We look forward to the application and promotion of more new materials and drive the continuous leap of lithium-ion battery technology.