What are the important technical indicators of graphite anode for lithium battery?
Lithium battery is an emerging industry with great development potential and prospects. In order to promote the healthy and orderly development of the industry, relevant industry standards are continuously formulated and released. Among them, the relevant technical standards for negative electrode material for lithium batteries have also been clearly specified. What are the specific indicators?
Crystal structure of graphite anode material
Different crystal structures and chemical compositions will cause the physical and chemical properties of the powder to vary widely, which will affect the application of the powder. The commonly used graphite anode material has two crystal structures, one is a hexagonal phase and the other is a rhombohedral phase. The degree of order of the crystal structure is related to the ease with which graphitization occurs. The greater the degree of graphitization, the easier the carbon material is to be graphitized, and the higher the degree of order of the crystal structure. The higher the degree of graphitization, the fewer the corresponding lattice defects, the smaller the resistance of electron migration, and the dynamic performance of the battery will be improved.
Particle size distribution of graphite anode material
The particle size distribution of the negative electrode material directly affects the slurrying process and volumetric energy density of the battery. In the case of the same volume filling fraction, the larger the particle size of the material, the wider the particle size distribution, and the smaller the viscosity of the slurry, which is beneficial to increase the solid content and reduce the difficulty of coating. In addition, when the particle size distribution of the material is wide, the small particles in the system can be filled in the voids of the large particles, which helps to increase the compaction density of the pole piece and improve the volume energy density of the battery.
Density of graphite anode material
Density refers to the mass per unit volume of a material in an absolutely dense state. Powder material are generally porous. According to whether these pore volumes are included, they can be divided into true density, effective density and apparent density, and apparent density is further divided into compacted density and tapped density. In practical applications, manufacturers are more concerned about the apparent density of material. For graphite anode, density directly affects the volumetric energy density of the battery. For the same material, the higher the compaction density is, the higher the volume energy density is, so the lower limit of each density is required in the standard.
The specific surface area of graphite anode material
The specific surface area of the graphite anode material has a great influence on the kinetic performance of the battery and the formation of the solid electrolyte membrane. If the specific surface area of graphite is too large, the initial capacity loss will be too much, and more binder will be added, resulting in an increase in internal resistance. The specific surface area of graphite is related to the shape and surface structure of graphite particles. For example, artificial graphite has a special microporous structure, a large specific surface area, more active sites, an increase in the reaction area, and a higher utilization rate of active material. capacity and high rate capability. It can be said that too large or too small specific surface area of graphite particles is not conducive to the reversible deintercalation of lithium ions, and only a suitable specific surface area can reversibly deintercalate lithium ions to a limited extent.
Requirements for pH and Moisture of graphite anode material
The pH and moisture of the graphite anode material have important effects on the stability of the material and the pulping process. The trace moisture contained in powder material can be measured by Karl Fischer coulometric titrator. for pH. The sample can be mixed with distilled water and measured with a pH meter.
Elemental content of graphite anode material
Graphite is mainly composed of three parts: fixed carbon, ash and volatile matter. Fixed carbon is the real electrochemically active component. The standard has strict requirements on the content of fixed carbon, at least greater than 99.5%. In addition, in addition to the main elements of fixed carbon and lithium, some impurity elements will be introduced during the modification process of coating and doping of the negative electrode material, which will also seriously affect the electrochemical performance of the battery and need to be strictly controlled. In addition, some negative electrode raw material contain restricted elements such as cadmium, lead, mercury, hexavalent chromium and their compounds, which are harmful to animals, plants and the environment, so there are strict restrictions on such substances in the standard.
First Reversible Specific Capacity and First Efficiency of graphite anode material
The first reversible specific capacity of the negative electrode material refers to the first-week delithiation capacity, and the first-time efficiency refers to the ratio of the first-week delithiation capacity to the lithium insertion capacity, which can largely reflect the electrochemical performance of the electrode material. Moreover, the reversible specific capacity of the battery in the first cycle can reflect the stable capacity of the material in the subsequent cycles to a certain extent, which also has important practical significance.
Graphite is one of the main anode material for lithium batteries. The ultrafine grinding of graphite is a key step, which affects the particle size distribution, specific surface area and crystal structure of the graphite anode material. Therefore, ultra-fine grinding equipment is very important.
High quality graphite anode for lithium ion battery supplier
Luoyang Moon & Star New Energy Technology Co., LTD, founded on October 17, 2008, is a high-tech enterprise committed to the research and development, production, processing, sales and technical services of graphite anode material, we are high quality graphite anode supplier. Our Company has a diversified product structure with natural graphite, artificial graphite, composite graphite, intermediate phase and other negative material (silicon carbon material, etc.). The products are widely used in high-end lithium ion digital, power and energy storage batteries.
If you are looking for graphite anode powder, please contact us. Or click on the needed products and send us an inquiry: firstname.lastname@example.org.