What are the characteristics of the "four overlords" of lithium battery cathode materials

The negative pole of lithium ion battery is made of the negative pole active material carbon material or the non-carbon material, the adhesive and the additive mix to make the paste adhesive evenly daub in the copper foil both sides, through the drying, the roll compression becomes. The cathode material is the main body of lithium ion battery, which makes lithium ion embedded and released during charging and discharging.

When a lithium battery is charged, lithium atoms in the positive electrode ionize into lithium ions and electrons, and lithium ions move to the negative electrode to synthesize lithium atoms with electrons. During discharge, lithium atoms ionize into lithium ions and electrons from the negative electrode surface in the graphite crystal, and synthesize lithium atoms at the positive electrode.

The cathode material mainly affects the first efficiency and cycling performance of lithium battery. The performance of the cathode material also directly affects the performance of lithium battery. The negative material accounts for about 5-15% of the total cost of lithium battery. The types of anode materials include carbon negative electrode and non-carbon negative electrode. From a technical point of view, the future lithium ion battery cathode material will present a diversity of characteristics.

With the progress of technology, the cathode material of lithium ion battery has developed from a single artificial graphite to natural graphite, mesophase carbon microspheres, artificial graphite, soft carbon/hard carbon, amorphous carbon, lithium titanate, silicon-carbon alloy and other anode materials coexist.

Four negative materials

Exclusive graphene

Graphene is a two-dimensional crystal made of carbon atoms only one atom thick. It is widely praised by scientists as the king of new materials for its thin texture, high hardness and fast electron movement. Although the "king" of excellent chemical properties by the new energy market, but so far still remain in the "conceptual" stage.

If graphene is used as a lithium anode material, it requires an independent upstream and downstream industrial chain, high price and complex process, which makes many anode material manufacturers shy away. Still, there are some domestic companies that are struggling to move forward. Currently, some well-known Chinese companies such as ampo, dafu technology and beitri have started to lay out graphene industry.

However, there are growing doubts in the industry about graphene as a cathode material. Some people believe that graphene has a very low density of vibration and compaction, as well as high cost, which makes the prospect of graphene as a battery cathode material very slim. But given its continuing popularity, it is fair to call it a one-party hegemon.

Control of the "home" of artificial graphite

At present, the anode materials are mainly natural graphite and artificial graphite. Hu bo, general manager of huzhou chuangya, said: "the natural graphite gram has high capacity, simple process and low price. Artificial graphite process more complex, more expensive, but better recycling and safety performance. Through various means of technical improvement, the two kinds of graphite anode materials can 'advantage and avoid disadvantages', but at present, artificial graphite for power batteries occupy a certain advantage.

And this one view also was proved in the market. According to relevant media research data, China's natural graphite output in the first quarter of this year was 4,770 tons, up 16.3% year-on-year. Shipments of artificial graphite reached 15,160 tons, up 110.5 percent year-on-year. According to the above data, the shipment of artificial graphite is much higher than that of natural graphite, and the important reason for this phenomenon is the strong demand for power batteries in the market so far this year.

Mesophase carbon microspheres with stable properties

Mesophase carbon microspheres are typical soft carbon with high degree of graphitization, stable structure and excellent electrochemical properties. According to the statistics of the research department of China resources network, in 2012, China's shipment of cathode materials was 27,650 tons, among which natural graphite accounted for 59%, artificial graphite 30%, and graphitized intermediate carbon microspheres 8%. In this regard, mesophase carbon microspheres are the third major carbon anode materials only next to natural graphite and artificial graphite.

According to coating online, the intermediate phase carbon microspheres have higher magnification performance than natural graphite and artificial graphite, and have obvious advantages when used in aircraft models and power tools. In addition, its thermal stability and chemical stability determines that it is not prone to chemical reactions, the use of lithium batteries to increase security. However, due to its high production cost, complex process and easy replacement, the production and marketing of mesophase carbon microspheres have been in a stable position without too much development.

New world silicon composite

Recently, an article attracted the attention of small make up, the title is "silicon" and "graphite" love and hate! . The theoretical capacity ratio of silicon anode materials reached over 4200mAh/g, much higher than that of graphite anode materials (372mAh/g). But natural defects of silicon anode materials, lithium is embedded in the silicon cell, can lead to serious inflation silicon, resulting in decreased capacity quickly, in order to overcome these shortcomings silicon anode materials and scientists will be silicon anode and graphite materials together, silicon carbon composite material comes, and is known as the "new world" li-ion battery anode materials.

According to coating online, the Model3 released by tesla USES silicon carbon negative electrode as a new material for power battery. By adding 10 percent silicon-based materials to the artificial graphite, tesla is able to achieve a battery capacity of more than 550mAh/g and a battery energy density of up to 300wh/kg. Now, the use of silicon-carbon composite materials to enhance the energy density of the battery is one of the industry recognized direction.

The "four overlords" of cathode materials have their own merits. But in the current market for cathode materials, the future of graphene is uncertain. In recent years has been in a consumer's first artificial graphite, also faces the challenge of high performance silicon carbon composite materials, the world's new energy automobile market leader tesla the use of silicon carbon composite material, is bound to bring about a boom of silicon carbide composites, affected by, the future lithium battery cathode material market or will reshuffle. However, the mesophase carbon microspheres, which have been in a stable position, will not produce much fluctuation in the future.

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