Графит для литий-ионных аккумуляторов

Lithium ion batteries occupy a pivotal position in today’s energy storage field. And graphite, as one of the key materials of lithium-ion batteries, its importance cannot be underestimated. Graphite, a layered mineral formed by a hexagonal arrangement of carbon atoms, has many unique physical and chemical properties. These make it an ideal choice for lithium-ion battery electrode materials. And provide strong support for the development of modern electronic devices and electric vehicles, pushing energy storage technology forward.

How is graphite used in batteries?

Lithium embedding and removal mechanism

When a lithium-ion battery is charged, lithium ions are removed from the positive electrode material and migrate to the negative electrode through the electrolyte solution. Because graphite has a layered crystal structure, these lithium ions can be embedded into the layers of graphite. Forming a “sandwich” -like structure, namely lithium-graphite intercalation compound. In the discharge process, the process is reversed. Lithium ions from the graphite layer, back to the positive electrode. Electrons flow in the external circuit to generate current, thus powering external devices. This embedding and deembedding mechanism is the core process of energy storage and release of graphite as a negative electrode material for lithium-ion batteries. And its reversibility and efficiency have a crucial impact on the overall performance of the battery.

Electrochemical reaction process

From the perspective of electrochemical reaction, the graphite negative electrode has a complex REDOX reaction during the battery charging and discharging process. At the initial stage of charging, the active site on the graphite surface first adsorbed lithium ions. With the decrease of potential, lithium ions gradually embedded in the graphite layers. And electrons flowed into the graphite from the external circuit to make the graphite undergo a reduction reaction. When discharging, on the contrary, lithium ions are removed from the graphite layer. The graphite oxidizes, and the electrons flow to the positive electrode through the external circuit. These complete a complete electrochemical reaction cycle. In this process, factors such as the composition and concentration of the electrolyte and the properties of the interface between the electrode and the electrolyte will affect the rate, efficiency and stability of the electrochemical reaction. And then affect the performance of the battery.

Why graphite used in lithium ion batteries?

Correlation between structural characteristics and performance

The layered structure of graphite is the key structural factor for its wide application in lithium ion batteries. This layered structure makes the graphite have a large layer spacing. It provides enough space for the embedding and deembedding of lithium ions. It is conducive to the realization of fast ion transport, thereby improving the charge-discharge ratio performance of the battery. At the same time, the van der Waals force between the layers is weak. So that lithium ions can enter and exit the graphite layer relatively easily. It reduces the activation energy of the reaction and improves the energy efficiency of the battery. Moreover, the crystal structure of graphite has high stability. It can maintain the integrity of the structure during the repeated embedding and deembedding of lithium ions. Reduce the attenuation of battery capacity caused by structural collapse. And ensure the long cycle life of the battery.

Advantages of physical and chemical properties

Graphite has good electrical conductivity, can effectively conduct electrons, reduce the ohm resistance inside the battery. And improve the charge and discharge efficiency and power performance of the battery. In terms of chemical properties, graphite has high chemical stability. And it is not easy to chemically react with the electrolyte in the working potential window of the battery. It avoids the adverse effects of gases and impurities caused by side reactions on the performance of the battery. In addition, the thermal stability of graphite is good. And it can withstand the heat generated during the battery charging and discharging process to a certain extent. This reduces the risk of thermal runaway of the battery and improving the safety of the battery. It is particularly important for large-scale energy storage systems and electric vehicles and other application scenarios.

Graphite battery vs lithium battery

Graphite batteries (usually refers to lithium-ion batteries with graphite as a negative electrode) are different from lithium batteries in many ways. In terms of energy density, the graphite battery is relatively mature and stable. And the energy density can meet most of the current scenarios. The new lithium battery such as the silicon-based lithium battery has a higher theoretical energy density. But the silicon-based material has a large volume change during charge and discharge, affecting the life cycle stability of the graphite battery.

In terms of cost, graphite reserves are rich, mining and processing technology is mature. And the cost is relatively low, while some new lithium batteries have high costs due to rare materials or complex preparation.

In terms of safety, the graphite battery has good thermal stability and is not easy to appear thermal runaway. And the new lithium battery needs to be further improved in this regard. At present, graphite batteries are widely used, but lithium batteries are developing rapidly in the field of scientific research. And if lithium batteries break through the technical bottleneck in the future, it is expected to form a competitive situation with graphite batteries in some high-end areas.

Specific application scenarios of graphite in lithium ion batteries

Consumer electronics

In smart phones, tablets, laptops and other consumer electronic products, lithium ion batteries need to have high energy density, long cycle life and good safety. To meet consumers’ demand for thin, portable devices and strong battery life. Lithium ion batteries with graphite negative electrode can well meet these requirements and provide a stable and reliable power supply for consumer electronic products. And make these devices able to operate normally in a variety of complex use scenarios. Such as long-term calls, high-intensity games, video playback, etc., becoming an indispensable part of modern people’s life and work.

Electric vehicle field

With the global concern for environmental protection and sustainable development, the electric vehicle market has risen rapidly. Lithium ion batteries with graphite negative электрод provide key power support for electric vehicles. And their high energy density helps to increase the driving range of electric vehicles and reduce the number of charges. The good magnification performance can meet the high power demand of electric vehicles under the conditions of acceleration and climbing. The long cycle life also reduces the cost of battery replacement, improves the economy and reliability of electric vehicles. It promotes the vigorous development of the electric vehicle industry. And it also helps the green transformation of the global automotive industry.

Energy storage system field

In renewable energy generation (such as solar energy, wind energy) grid-connected, smart grid peak filling and household energy storage and other energy storage systems, lithium ion batteries need to have large capacity, long life, high safety and low cost. Lithium ion batteries with graphite negative electrode have certain advantages in these aspects. This can effectively store excess electrical energy and release it when needed, balance power supply and demand. It improves energy efficiency, enhances the stability and reliability of the power grid. And it also promotes the large-scale application of renewable energy and the optimization of the energy structure.

 Graphite battery price

As a relatively rich mineral resource, graphite has a relatively low cost. This makes lithium ion batteries with graphite as a negative electrode have a certain competitiveness in price. However, with the rapid development of the lithium-ion battery market and the continuous improvement of battery performance requirements, the quality and processing technology of graphite are also constantly upgrading. This will affect its cost to a certain extent. In addition, other raw material costs, process costs, research and development costs, and market supply and demand factors in the battery production process will also comprehensively affect the final price of graphite batteries. Overall, the current performance of graphite batteries is more outstanding in terms of cost performance. And it can meet the needs of most application scenarios. But with the progress of technology and market changes, its price may also fluctuate and adjust accordingly.

Заключение

As an important component of lithium-ion batteries, graphite plays a vital role in the field of energy storage. Its unique physical and chemical properties make it have obvious advantages in the performance, cost and application range of batteries. It is widely used in many fields such as consumer electronics, electric vehicles and energy storage systems. And it promotes the development of modern science and technology and society.