Analysis of advantages and application of dry electrode technology

As the key technology and infrastructure of the new energy industry, batteries play a vital role in the development and innovation of new energy vehicles, energy storage systems and other fields. Therefore, battery innovation is not only related to the development and competitive advantages of the top 10 lithium battery companies in the world themselves, but also to the future development of the entire new energy industry.

Dry electrode technology, as an innovative technology in the battery preparation process, is gradually becoming a major driver of industrial upgrading and technological progress.

1. Introduction to dry electrode

Dry electrode refers to a preparation method for electrode materials used in the preparation of lithium-ion batteries. The preparation process of dry electrodes does not require the use of traditional liquid electrolyte infiltration, but the electrodes are prepared by directly compacting dry powder electrode materials containing active substances. Compared with the liquid electrolyte infiltration preparation method, the dry electrode has the following advantages:

Higher active material compaction density

Since no liquid electrolyte is required in the dry electrode preparation process, more active materials can be directly compacted into the electrodes, resulting in higher active material compaction densities. This can increase the capacity and energy density of the electrode, which in turn improves the performance of the battery.

Better electrochemical stability

There is no need to use a liquid electrolyte during the preparation of the dry electrode, so the corrosion and electrochemical instability of the electrode material by the liquid electrolyte can be avoided, thereby improving the cycle life and safety performance of the battery.

Simpler preparation process

Compared with the traditional liquid electrolyte infiltration preparation method, the dry electrode preparation method is simpler, faster, and easier to operate. In summary, the dry electrode preparation method has many advantages, the most notable of which is that it can achieve a higher active material compaction density, which can further improve the performance of the battery, and the energy density of the battery can be increased by 20% under the same conditions.

Comparison of dry electrode vs wet electrode

2. Coating process of dry electrode

The coating process is a process of coating one or more layers of liquid on a substrate based on the study of the physical properties of the fluid. The substrate is usually a flexible film or backing paper, and then the applied liquid coating is dried or cured in an oven to form a film layer with special functions.

Coating thickness is an important parameter in battery performance, which will directly affect the performance of the electrode, including battery capacity, cycle life, charge and discharge rate, etc. If the coating thickness of the electrode is too thin, the quality of the active material will be insufficient, and the active area of the electrode surface will be insufficient, thereby reducing the capacity and discharge capacity of the battery.

On the other hand, if the coating thickness of the electrode is too thick, the diffusion rate of the electrolyte will slow down, which will affect the cycle life and charge and discharge rate of the battery.

In wet electrode coating, the limit value of coating thickness is usually around 160 microns. During the wet coating process, the coating liquid will form a layer of coating on the surface of the electrode substrate, and if the coating thickness is too thick, the electrode structure will be unstable, and even defects such as bubbles will be generated, which will affect the performance of the electrode.

In dry electrode coating, since the coated material is dry powder, the coating thickness can be controlled in a wider range. Generally speaking, the thickness range of dry electrode coating is between 30-5000 microns, and coatings in this range can achieve good electrode structure and high electrode performance. However, an overly thick coating will increase the internal resistance of the electrode and reduce the transfer efficiency of the electrode, so the coating thickness needs to be carefully controlled during the coating process to achieve the best electrode performance.

3. Application of dry electrode

The 4680 battery has a diameter of 46mm and a height of 80mm, and its capacity is nearly five times higher than that of the traditional 21700 battery. This battery uses ternary lithium-ion battery technology, which can provide higher energy density and cycle life. The introduction of Tesla's 4680 battery is undoubtedly a major breakthrough in the field of battery preparation for dry electrode technology.

On February 5, 2019, Tesla acquired Maxwell, a supercapacitor manufacturer, at a premium of 55%. It mainly focused on Maxwell's unique dry electrode technology, and learned from switching to the battery pole piece production process to make technical reserves for subsequent solid-state batteries.

In the dismantling data, the research team found that the 4680 battery did not fully use dry electrode technology. Currently, 4680 only uses dry electrode technology on the anode, while the cathode does not use dry electrode technology due to special reasons. But even so, the 4680 still achieves a higher energy density than 18650 battery and 21700 battery.

At present, the energy density of the ternary cell of the 4680 battery has reached 244-283 Wh/kg, and the energy density of the 4680 battery pack has also reached 210Wh/kg, exceeding the energy density of most battery packs currently on the market.

Although the 4680 battery has not been fully applied in dry electrode technology, its new battery design, electrolyte and manufacturing process improvements have all improved its performance in terms of energy density and cycle life. This battery has been widely used in Tesla's electric vehicles and energy storage products, and has also received extensive attention and research.

It is foreseeable that with the continuous promotion and improvement of dry electrode technology in the field of battery preparation, key performances such as energy density and cycle life of batteries will be more optimized, and the future of the battery industry will be brighter and more sustainable. Tesla's application of dry electrode technology is not only a milestone in battery technology innovation, but also injects new vitality and impetus into the development of electric vehicles and energy storage.

In areas such as electric vehicles, increased energy density is an important key to achieving long range and fast charging. Therefore, the application of dry electrode technology will bring broader space and higher possibilities for the development of electric vehicles, energy storage and other fields.

Of course, dry electrode technology is not perfect, and the requirements for battery preparation process and equipment are relatively high, requiring more refined preparation and more professional technical support. However, with the continuous development and improvement of science and technology, the application of dry electrode technology will become more and more extensive, and will bring new technological innovation and business opportunities to the battery industry.

4. Conclusion

Dry electrode process technology is an ideal process route for a new generation of batteries. If you master dry electrode technology, you can take the lead in future industry competition.

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