How can graphite be used in lithium batteries?

Graphite comes from the Greek word graphein. It has heat resistance, electrical and thermal conductivity, chemical passivation (corrosion resistance), and is lighter than aluminum. In addition to lithium ion anodes, advanced graphite is also used in fuel power batteries, solar cells, semiconductors, LEDs and nuclear reactors. It is expensive to process anode grade graphite with a purity of 99.99%, and the process is wasteful. The final cost is not the material, but the purification process. Recycling old lithium ions to recover graphite will not deal with this problem because it is a cumbersome purification process. Carbon and graphite are related substances. Graphite is an allotrope of carbon, a structural modification that occurs by combining elements in different ways. Graphite is the most stable form of carbon. Diamond is a metastable carbon allotrope. It is known for its excellent physical properties. It is not as stable as graphite, which is soft and plastic. The diameter of carbon fiber is about 5-10 microns, which is one-tenth the thickness of a human hair. The carbon atoms are held together in microscopic crystals and are very strong. They are woven in a textile fashion and mixed with a polymer matrix, which is a hardened form of carbon fiber, which is as strong as steel but lighter. These materials are used in golf clubs and bicycle frames, as well as car and airplane body parts to replace aluminum. Carbon fiber is widely used in Boeing 787 and Airbus 350X. Currently, graphite for batteries only accounts for 5% of global demand. There are two forms of graphite: natural graphite from mines and synthetic graphite from petroleum coke. Both types are used for lithium ion anode materials, and 55% tend to balance synthetic and natural graphite. Manufacturers prefer synthetic graphite because of its consistency and purity better than natural graphite. This situation is changing. Through modern chemical purification processes and thermal solutions, the purity of natural graphite reaches 99.9%, while the purity of synthetic equivalent reaches 99.0%. Purified natural flake graphite has a higher crystal structure, and has better electrical and thermal conductivity than synthetic materials. Switching to natural graphite can reduce processing costs while having the same or better lithium ion performance. Lithium-ion synthetic graphite sells for about US$10,000 per ton, while spherical graphite made from natural flakes sells for US$7,000 (2015 price). Unproduced natural graphite is much cheaper. In addition to cost, natural graphite is more environmentally friendly than synthetic graphite; it is also the basis of graphene and is a scientist's dream. As of the end of 2016, natural graphite accounted for 60-65% of the market share; synthetic ingredients were about 30%, while alternatives such as lithium titanate, silicon and tin were about 5%. Graphene Graphene is an allotrope of carbon in the form of a two-dimensional hexagonal lattice. Graphene is currently only one atom thick in a piece of pure carbon. It is flexible, translucent, impervious to moisture, stronger than diamond, and more conductive than gold. Experts suggest that graphene is a miracle material that can improve many products, including batteries. It is said that graphene anodes retain energy better than graphite anodes, and the charging time is guaranteed to be ten times faster than current lithium batteries. Regarding conventional graphite anodes, lithium ions accumulate around the outer surface of the anode. By allowing lithium ions to pass through the micropores of graphene sheets with a size of 10-20 nm, graphene has a more elegant processing method. This guarantees the best storage area and easy extraction. Once available, it is estimated that this battery can store ten times more electrical energy than lithium batteries with conventional graphite anodes. The graphene is further improved by adding vanadium oxide to the cathode. It is said that the test battery with this enhanced function was recharged within 20 seconds and maintained 90% capacity after 1000 cycles. Graphene is also probed in supercapacitors to increase specific energy density, as well as solar cells. The figure below shows the magical lattice of graphene visible using a scanning probe microscope (SPM). The structure of graphene scanning probe microscope (SPM) shows the image of graphene. For decades, scientists have conducted theoretical research on the miracle of graphene, but no commercial product specifically uses this distinct miracle material. The miracle of graphene is likely to have been used in pencils and other products for centuries, so a better understanding of its mechanism will eventually lead to product improvements. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: Comparative analysis of polymer batteries and liquid lithium batteries