How is the high energy density of lithium battery cells achieved?
Publish Time: 2025-02-04
As an important carrier of modern energy storage, the improvement of lithium battery's energy density has always been the focus of attention inside and outside the industry. High energy density means that lithium batteries can store more electrical energy at the same volume or weight, which is of great significance for improving the range of electric vehicles, extending the use time of consumer electronic devices and optimizing the efficiency of energy storage systems.1. Material innovation: breakthroughs in positive electrode, negative electrode and electrolytePositive electrode material: The positive electrode is the main place for storing lithium ions in lithium battery cells, and its performance directly determines the energy density of the battery. In recent years, the research and development and application of high-nickel ternary materials (such as NCM811) have significantly improved the energy density of the battery cell. By adjusting the ratio of nickel, cobalt and manganese, especially increasing the nickel content, the specific capacity of the battery cell can be effectively improved. In addition, new positive electrode materials such as lithium-rich manganese-based oxides and sulfides are also being explored. These materials have higher theoretical specific capacity and discharge voltage, which provides the possibility of further improving energy density.Negative electrode material: The innovation of negative electrode material is also crucial to improving energy density. Silicon-carbon composite materials have attracted widespread attention because of their theoretical specific capacity far higher than that of traditional graphite negative electrodes. However, silicon has a volume expansion problem during the charging and discharging process. Through technical means such as nanostructured silicon and silicon oxide, the expansion phenomenon can be effectively reduced, thereby improving the battery energy density. In addition, lithium metal negative electrodes have become a research hotspot due to their extremely high theoretical capacity. Although their cycle stability still needs to overcome problems such as dendrites, the development of technologies such as solid electrolytes and advanced surface coatings has made it possible for lithium metal negative electrodes to be practical.Electrolyte materials: Solid electrolytes have great potential in improving battery safety and energy density due to their high ion conductivity and non-flammability. Oxide- or sulfide-based solid electrolytes are receiving widespread attention, and they are expected to replace traditional liquid electrolytes, thereby improving the overall performance of the battery.2. Structural optimization and process improvementIncreasing the size of the battery cell: Increasing the size of the battery cell within a certain range can achieve capacity expansion, but attention should be paid to the heat dissipation and safety of the battery cell. Therefore, increasing the size of the battery cell needs to be combined with other technical means to improve battery performance.Optimize the arrangement structure: By carefully designing the internal layout of the battery cell, such as adopting a more compact battery pack structure and optimizing the layout of the battery management system, the space utilization rate can be improved, thereby increasing the energy density of the battery cell.Improve the production process level: Increasing the compaction density of the main material, using thinner foil and other technical means can increase the battery capacity in a limited space. For example, CATL has improved the energy density of the battery cell by using 6-micron copper foil.Reduce the proportion of inactive substances: Reducing the mass or volume ratio of inactive ingredients such as electrolytes, conductive additives and adhesives in the battery cell can increase the proportion of active substances and thus increase the energy density.The high energy density of lithium battery cells is achieved through a variety of means such as material innovation, structural optimization and process improvement, and technological innovation.
