Lithium-ion batteries have many advantages such as high energy density, long cycle life, small self-discharge, no memory effect, and environmental friendliness. They have been widely used in consumer electronics, power tools, electric vehicles, and large-scale energy storage. showing a rapid growth trend.
Negative electrode materials are important electrode materials for lithium-ion batteries. my country has successively promulgated a number of relevant national standards, which have played a guiding role in the actual production and application of negative electrode materials. Among them, the particle size distribution, as an important physical and chemical index of the negative electrode material, directly affects the pulping process and volume energy density of the battery, which is mainly reflected in the following aspects:
Particle Size Distribution Affects Volumetric Energy Density
The particle size of the negative electrode material should have a suitable particle size distribution. The small particles in the system can fill the gaps of the large particles, which helps to increase the compaction density of the electrode sheet, thereby increasing the volumetric energy density of the battery.
Particle size distribution affects charge and discharge performance
The smaller the particles of the negative electrode material, the smaller the van der Waals force that needs to be overcome when lithium ions are intercalated, and the easier the intercalation is, and the smaller the particles, the shorter the channels for lithium ion intercalation and extraction, which is more conducive to quickly achieving a full lithium intercalation state. , so as to have better charge and discharge performance.
Particle size distribution affects cycle performance
Experiments have shown that graphite negative electrodes with smaller particles have larger initial capacity, but also larger irreversible capacity; as the particle size increases, the initial charge and discharge capacity decreases, and the irreversible capacity decreases. At the same time, the smaller the graphite particles, the larger the specific surface area in contact with the electrolyte, the more charges will be consumed by the SEI film formed during the initial charge and discharge process, and the greater the irreversible capacity loss will be. Therefore, a reasonable particle size distribution can not only improve the initial capacity and initial efficiency of lithium-ion batteries, but also improve the cycle performance of lithium-ion batteries.
Particle size distribution affects the production process
The particle size distribution of the negative electrode material will directly affect the pulping and coating process of the battery. In the case of the same volume filling fraction, the larger the particle size of the material and the wider the particle size distribution, the smaller the viscosity of the slurry, which is conducive to increasing the solid content and reducing the difficulty of coating.
With the rapid development of lithium-ion batteries, new materials and new processes are constantly emerging, and there will be more and more types of negative electrode materials for lithium-ion batteries, and the particle size distribution requirements will also change accordingly.