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An article to understand lithium battery anode materials

An article to understand lithium battery anode materials

(Summary description)As we all know, the four main materials of lithium batteries include positive electrode material, negative electrode material, electrolyte, and separator. So, what is the position of the anode material in the lithium battery material?

An article to understand lithium battery anode materials

(Summary description)As we all know, the four main materials of lithium batteries include positive electrode material, negative electrode material, electrolyte, and separator. So, what is the position of the anode material in the lithium battery material?

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As we all know, the four main materials of lithium batteries include positive electrode material, negative electrode material, electrolyte, and separator. So, what is the position of the anode material in the lithium battery material?

Generally speaking, the negative electrode material of lithium battery is made of active materials, binders and additives, and then it is applied to both sides of copper foil, and then dried and rolled. Its function is to store and release energy, which mainly affects the lithium battery. The cycle performance and other indicators.

Anode materials can be divided into two categories: carbon materials and non-carbon materials according to the active materials used:

``Carbon-based materials include graphite materials (natural graphite, artificial graphite, and mesophase carbon spheres) and other carbon systems (hard carbon, soft carbon and graphene) two routes;

Non-carbon-based materials can be subdivided into titanium-based materials, silicon-based materials, tin-based materials, nitrides, and metallic lithium.

Different from the cathode material, although the lithium battery anode has many routes, the final product is very single, and artificial graphite is the absolute mainstream. Data show that China's artificial graphite shipments in 2020 will be about 307,000 tons, accounting for 84% of the total anode material shipments, which is a further 5.5% increase from the 2019 level.

Compared with other materials, artificial graphite has good cycle performance, superior safety, mature technology, easy access to raw materials, and low cost, making it an ideal choice.

The core problem of graphite anodes is that the theoretical upper limit of the energy density of graphite anode materials is 372mAh/g, and the products of leading companies in the industry can achieve an energy density of 365mAh/g, which is approaching the theoretical limit, and there is very limited room for improvement in the future. There is an urgent need to find next-generation alternatives.

Among the new generation of anode materials, silicon-based anodes are popular candidates. It has a very high energy density, and the theoretical capacity ratio can reach 4200mAh/g, far exceeding graphite materials [14]. However, as a negative electrode material, silicon also has serious defects. The intercalation of lithium ions can cause serious volume expansion, damage the battery structure, and cause a rapid decrease in battery capacity.

One of the current solutions is to use silicon-carbon composite materials. Silicon particles are used as the active material to provide lithium storage capacity. Carbon particles are used to buffer the volume change of the negative electrode during the charge and discharge process, improve the conductivity of the material, and avoid silicon. The particles agglomerate during the charge-discharge cycle.

Based on this, silicon-carbon anode materials are considered to be the most promising technical route, and gradually gain the attention of enterprises in the industry chain. Tesla's Model 3 has used artificial graphite anode batteries mixed with 10% silicon-based materials, and its energy density has successfully achieved 300wh/kg, which greatly adopts traditional technology routes.

However, compared with graphite anodes, in addition to the immature processing technology of silicon carbon anodes, the higher cost is also an obstacle. The current market price of silicon carbon anode materials exceeds 150,000 yuan/ton, which is twice that of high-end artificial graphite anode materials. After mass production in the future, battery manufacturers will also face cost control issues similar to those of cathode materials.

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