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When there is only a low content of CMC in the slurry without SBR, graphite particles agglomerate during the homogenization process and cannot be well dispersed. When the ratio of CMC to graphite is moderate, adding 1.0% to 4.5% of SBR to the slurry will cause SBR to adsorb on the surface of graphite, dispersing the graphite particles and reducing the viscosity and modulus of the slurry. When the amount of CMC is 0.7% to 1.0%, the slurry exhibits viscoelasticity, and continuous addition of SBR will not change the rheological properties of the slurry. Comparing the two mixing methods of adding SBR and CMC simultaneously and adding CMC first and then SBR, the results show that CMC plays a leading role in the dispersion of graphite in the slurry, and CMC preferentially adsorbs on the surface of graphite particles. In general, when the amount of CMC added is very low, the addition of SBR will adsorb on the surface of graphite particles, which has a certain impact on the dispersion of graphite. As the amount of CMC added increases, the amount of adsorption on the surface of graphite also increases, and SBR cannot adsorb on the surface of graphite, thus playing no role in the dispersion of graphite. When a certain amount of CMC is reached, the combined attraction of excess CMC that fails to adsorb on the surface of graphite particles becomes greater than the repulsion, which can lead to agglomeration between graphite particles. Therefore, CMC plays a crucial role in the dispersion of graphite negative electrode slurry. Email :tob.amy@tobmachine.com Skype :amywangbest86 Whatsapp/Phone number :+86 181 2071 5609

Double planetary mixer Currently, the mainstream slurry mixing equipment used by lithium-ion battery manufacturers is the double planetary mixer, also known as the PD mixer. This mixer is equipped with a low-speed mixing component, Planet, and a high-speed dispersing component, Disper. The low-speed mixing component comprises two folding frame agitators that utilize planetary gear transmission. As the agitators rotate and orbit, they allow the material to move in various directions, achieving the desired mixing effect within a relatively short time. The high-speed dispersing component typically features a toothed dispersing disk that rotates along with the planetary carrier while spinning rapidly, exerting intense shearing and dispersing forces on the material. This effect is several times greater than that of ordinary mixers. Additionally, the dispersing component can be configured with either a single or double dispersing shaft, depending on the specific requirements of the application. Ball mill mixing Ball milling mixing is also often used for the preparation of lithium-ion battery slurry, which is generally more common in laboratories. Similar to fluid mechanics-based mixing methods, the dispersion ability of the ball milling process is determined by the balance of cluster fragmentation and agglomeration reorganization speeds, which is related to the properties of powder particles and can be changed by the addition of surfactants. In the ball milling process, powder particles undergo a large number of surface and volumetric changes, which may lead to mechanical and chemical transformations of the material (such as the rupture of carbon nanotubes, changes in their aspect ratio and structure). Reactions may occur between particles, between powder and dispersing media (solvents and binders), and even between powder and grinding balls. Collisions between grinding balls and local fluid high-shear turbulence can also cause the rupture of binder molecules. Ultrasonic stirring Currently, ultrasound is used by people for mixing at the microscopic scale based on the transient acoustic cavitation effect. This effect needs to be generated under quite high ultrasonic intensity, accompanied by the formation and growth of a large number of microbubbles. When the bubble size reaches a certain critical value, the bubble growth rate increases rapidly and then ruptures instantly, forming shock waves to disperse agglomerates while causing local high temperature and high pressure (local pressure can reach thousands of atmospheres). Another process that occurs during ultrasonic mixing is the macroscopic flow of the liquid. The concentration of cavitation bubbles gradually decreases along the axis centered on the generator, and the bubbles diffuse to low-concentration regions, driving the liquid to flow with a speed of up to 2m/s. This fluid flow is sufficient to provide adequate mixing effects without the need for additional equipment. Email :tob.amy@tobmachine.c...

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1.Battery material aging and decay The materials inside lithium batteries mainly include: positive and negative electrode active materials, binders, conductive agents, current collectors, separators, and electrolytes. During the use of lithium batteries, these materials undergo a certain degree of decay and aging. Tang Zhiyuan et al. believed that the factors causing capacity decay in manganese acid lithium batteries include dissolution of the positive electrode material, phase changes in the electrode material, electrolyte decomposition, formation of an interfacial film, and corrosion of the current collector. Vetter et al. systematically and deeply analyzed the changes in the positive electrode, negative electrode, and electrolyte of the battery during cycling. The author believed that the formation and subsequent growth of the SEI film on the negative electrode would be accompanied by irreversible loss of active lithium, and the SEI film did not possess true solid electrolyte functionality. The diffusion and migration of substances other than lithium ions would lead to gas generation and particle rupture. In addition, changes in material volume during cycling and the precipitation of metal lithium would also lead to capacity loss. 2. Charge and discharge system  The charge and discharge system mainly includes three aspects: charge and discharge method, rate, and cut-off conditions. Regarding the charge method, American scientist Mas proposed the concept of an optimal charging curve. He believed that the optimal charging current of a battery gradually decreases as the charging time increases, which can be expressed by the formula I=I0e-αt. In this formula, I represents the receivable charging current; I0 represents the maximum initial current at the time t=0; t represents the charging time; and α represents the decay constant. The relationship curve between I and t is shown in follow Figure. 3.Temperature Different types of lithium batteries have different optimal operating temperatures, and both excessively high and low temperatures can have an impact on the service life of the batteries. 4.Cell Consistency Battery packs typically consist of hundreds or even thousands of individual cells connected in series or parallel. In addition to the aforementioned factors influencing their cycle life, cell consistency is another crucial factor. Due to differences in materials and manufacturing processes, it is challenging to ensure the consistency of lithium-ion battery cells. In terms of materials, the uniformity of positive and negative electrode materials and electrolytes is crucial. Lithium batteries produced from the same materials and in the same batch often exhibit relatively better consistency. In terms of manufacturing, the production process of lithium batteries is complex, involving multiple process parameters at each step. Poor control can lead to inconsistencies in parameters such as battery voltage, capacity, and internal resistance. E...

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Electrode piece coating generally refers to a process in which the evenly stirred slurry is evenly coated on the current collector and the organic solvent in the slurry is dried. The effect of coating has an important impact on the battery capacity, internal resistance, cycle life and safety, and ensures that the pole piece is evenly coated. The selection of coating methods and control parameters have an important impact on the performance of lithium-ion batteries, which are mainly manifested in: 1) Coating drying temperature control: if the drying temperature is too low during coating, it cannot guarantee that the pole piece is completely dry, if the temperature is too high, it may be because the organic solvent inside the pole piece evaporates too quickly, and the surface coating of the pole piece cracks and falls off; 2) Coating surface density: if the coating surface density is too small, the battery capacity may not reach the nominal capacity, if the coating surface density is too large, it is easy to cause batching waste, and if the positive electrode capacity is excessive in serious cases, lithium dendrites will be formed due to the precipitation of lithium to puncture the battery separator and cause a short circuit, causing potential safety hazards; 3) Coating size: The coating size is too small or too large may cause the positive electrode inside the battery to not be completely wrapped by the negative electrode, during the charging process, lithium ions are embedded from the positive electrode and move to the electrolyte that is not completely wrapped by the negative electrode, the actual capacity of the positive electrode can not be played efficiently, and in serious cases, lithium dendrites will be formed inside the battery, which is easy to puncture the separator and cause the internal circuit of the battery;   4) Coating thickness: If the coating thickness is too thin or too thick, it will have an impact on the subsequent electrode rolling process, and the performance consistency of the battery electrode piece cannot be guaranteed. Selection of coating equipment and coating process The coating process in a broad sense includes: uncoiling→ splicing→ tension control → pulling tabs→ coating → drying→ guiding → tension control→ guiding → winding and other processes. The coating process is complex, and there are many factors that affect the coating effect, such as: the manufacturing accuracy of the coating equipment, the smoothness of the equipment operation, the control of the dynamic tension in the coating process, the size of the air volume in the drying process and the temperature control curve will affect the coating effect, so it is extremely important to choose the appropriate coating process.   Generally, the selection of coating method needs to be considered from the following aspects, including: the number of layers to be coated, the thickness of the wet coating, the rheological properties of the coating solution, the...

1.Lithium battery tab material Lithium-ion battery tabs, as shown in the figure below, are metal conductors that lead the positive and negative electrodes out of the battery cells. The complete tabs are mainly composed of insulating sealant and metal conductive matrix. For lithium-ion batteries, the positive electrode uses aluminum tabs, and the negative electrode uses pure nickel tabs or nickel-plated copper tabs. 2. Lithium battery tab structure The internal structure of consumer lithium-ion batteries is mainly divided into four types according to their production methods: normal structure, tab-centered structure, multi-tab structure, and laminated structure. The normal structure of the positive and negative electrodes has only one tab, which is located at one end of the pole piece and is made by winding; the tab in the middle structure is located in the middle of the batteryelectrode, usually through laser cleaning, spacer coating, tape application, etc. The internal resistance of the battery is smaller and the rate performance is better; the multi-tab woundelectrodehas multiple tabs, and the tab positions are different according to the design. The battery resistance is smaller and the rate performance of the battery is better; stacked The sheet battery is made by cutting theelectrodeinto a specific shape and alternately folding the positive and negative electrodes. There is a tab in each layer. The battery with this structure has the best rate performance. 2.1Tab-centered structure The position of the tabs has a significant impact on the internal resistance and rate of the lithium-ion battery. When the tabs are in the middle of the positive and negative electrodes, the battery has the best internal resistance and rate performance, and its performance is close to that of batteries with lamination technology. The picture below shows a comparison between the pole-tab center-mounted structure and the normal structure. The pole-tab of the normal structure is located at one end of the pole piece, while the pole-tab-centered structure has the pole tab located in the middle of the battery pole piece. 2.2 Multi-tab winding structure Thepicture below shows the multi-pole winding structure. The multi-tab winding technology cuts a fixed tab shape into the carrier. After the winding is completed, the carrier is welded and the tabs are drawn out to form a multi-tab battery. Multi-taab winding has more tabs and is more evenly distributed. This structure has better battery rate performance and smaller charge and discharge temperature rise. It is suitable for high-power equipment. Currently, many drones use this structure. Due to its welding requirements and higher precision, batteries made with this structure are more expensive. The advantages of the multi-tab structure are: further reducing the battery impedance, improving the battery's high-rate charge and discharge performance, and supporting 5C~10C discharge; effectively reducing the temperature rise of ...

1. The battery is swollen and leaking If the water content in the lithium-ion battery is excessive, it will chemically react with the lithium salt in the electrolyte to form HF: Hydrofluoric acid (HF) is a very corrosive acid that can be very damaging to battery performance: HF destroys the SEI membrane (Solid-Electrolyte-Interface) inside the battery and reacts with the main components of the SEI membrane: Finally, LiF precipitation is generated inside the battery, so that the lithium ions undergo an irreversible chemical reaction in the negative electrode piece of the battery, and the active lithium ions are consumed, and the energy of the battery is reduced.   When there is enough water, more gas is generated, and the pressure inside the battery will increase, which will cause the battery to be deformed by force, and there will be dangers such as bulging and leakage of the battery.   Most of the battery swelling and opening the cover encountered in the use of mobile phones or digital electronic products on the market are caused by high moisture and gas production swelling inside the lithium battery. 2.The internal resistance of the battery becomes larger The internal resistance of the battery is one of the most important performance parameters of the battery, and it is the main indicator to measure the difficulty of the transmission of ions and electrons inside the battery, which directly affects the cycle life and operating state of the battery. The smaller the internal resistance, the less voltage is occupied when the battery is discharged, and the more energy is output. When the water content increases, POF3 and LiF precipitation will be generated on the surface of the SEI membrane (Solid-Electrolyte-Interface) of the battery, which will destroy the compactness and uniformity of the SEI membrane, resulting in the gradual increase of the internal resistance of the battery and the continuous decrease of the discharge capacity of the battery. 3. Shortened cycle life The water content is too large, which destroys the SEI film of the battery, the internal resistance gradually increases, the discharge capacity of the battery becomes smaller and smaller, the use time of the battery becomes shorter and shorter after each full charge, the number of charging and discharging (cycles) of the battery that can be used normally will naturally decrease, and the service time (life) of the battery will be shortened.  Email :tob.amy@tobmachine.com  Skype :amywangbest86  Whatsapp/Phone number :+86 181 2071 5609