The characteristics and development direction of current lithium-ion battery anode materials

by:CTECHi     2021-09-20
With the diversified development of the world, our lives are constantly changing, including the various electronic products we come into contact with. Then you must not understand some of the components of these products, such as lithium-ion battery anode materials. With the depletion of non-renewable energy sources such as coal, oil and natural gas, and environmental pollution caused by their combustion, energy and the environment have become two important issues affecting the sustainable development of the world today. In order to solve these two problems, it is urgent to develop new renewable green energy sources to replace traditional fossil fuels. As a new generation of energy storage equipment, lithium-ion batteries have the advantages of high energy density, high working voltage, long cycle life, low environmental pollution, and no memory effect. It is currently one of the most promising energy storage devices. [1] As the core component of lithium-ion batteries, electrode materials determine the performance of lithium-ion batteries, and negative electrode materials play a vital role in lithium-ion batteries. Therefore, research on anode materials has become a hot spot in recent years. The global sales volume of anode materials for lithium-ion batteries is about 100,000 tons, mainly to my country and Japan. According to the current upward trend of new energy vehicles, the demand for anode materials will continue to rise. At present, the world's lithium-ion battery anode materials are still dominated by natural/artificial graphite, and new anode materials such as medium carbon microspheres (MCMB), lithium titanate, silicon-based anodes, HC/SC and lithium metals are also rapidly increasing. The negative electrode material is one of the key factors that determine the performance of lithium-ion batteries. The current negative electrode materials used in commercial lithium-ion batteries mainly include: ①graphite carbon materials, which are divided into natural graphite and artificial graphite; ②disordered carbon materials, including hard carbon And soft carbon; ③ lithium titanate materials; ④ silicon-based materials, mainly divided into carbon-coated silicon oxide composite materials, nano-silicon-carbon composite materials, and amorphous silicon alloys. With the rapid development of economy and technology, the popularity of electronic products has reached the highest level in history. As one of the important application areas, the development of electric vehicles has promoted the improvement of battery performance, but also put forward higher requirements for batteries, including increasing energy density and extending cycle life. The current research on anode materials focuses on new carbon materials, silicon-based materials, tin-based materials and their oxide anode materials. The insertion redox potential of lithium ions in the negative electrode matrix is u200bu200bas low as possible, close to the potential of metal lithium, so the input voltage of the battery is high; a large amount of lithium in the matrix can be reversibly inserted and deintercalated to obtain high capacity; in the deintercalation process , The important structure of the negative electrode remains unchanged or rarely changes. With the insertion and removal of lithium, the change in the redox potential should be as small as possible so that the battery voltage does not change significantly, and stable charging and discharging can be maintained. Compared with traditional carbon materials, new carbon materials are currently widely used commercially as conventional carbon materials for lithium-ion batteries, but their theoretical capacity is low, and they are increasingly unable to meet the development needs of lithium-ion batteries. New carbon materials, such as carbon nanotubes, graphene, etc., have great potential in lithium-ion battery applications due to their special one-dimensional and two-dimensional flexible structures, excellent thermal and electrical conductivity. Graphite has many excellent properties, so it is widely used in metallurgy, machinery, electrical, chemical, textile, national defense and other industrial sectors, such as graphite molds, graphite electrodes, graphite refractories, graphite lubricating materials, graphite sealing materials, etc. my country is the country with the richest graphite reserves in the world, as well as the largest producer and exporter. It occupies an important position in the world's graphite industry. According to statistics from the Ministry of Land and Resources, my country has 30.85 million tons of crystalline graphite reserves and 52.8 million tons of basic reserves. Cryptocrystalline graphite reserves are 13.58 million tons, and basic reserves are 23.71 million tons. my country's graphite reserves account for more than 70% of the world's. Graphite is currently the most commonly used anode material for lithium-ion batteries. Due to the layered structure of graphite, lithium ions can only interact with the six-membered carbon ring of sp2 hybridization to form LiC6. Through this calculation, the theoretical specific capacity of graphite is 372 mA·h. /G. Regarding graphene, both sides of the sheet can store lithium ions at the same time, so the theoretical capacity can reach 740mA·h/g. Studies have shown that lithium may be embedded in disordered carbon materials in the form of Li2 covalent molecules to form LiC2. The theoretical specific capacity of graphene calculated by this lithium storage mechanism is 1116mA·h/g. In summary, the lithium ion storage capacity of graphene is much higher than that of graphite, so it has great potential for development as a negative electrode material for lithium ion batteries. In the process of research and design, there must be problems of this kind or that kind. This requires our scientific researchers to continuously summarize relevant experience in the design process, so as to promote the continuous innovation of products.
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