Maybe one day, you will fold a touchscreen tablet into two stacks in your pocket; fully charge your phone in a few seconds, and use it for half a month without recharging; take an ultralight plane, drive a light car, or even board a human being The 10,000-mile space elevator of dreams...
All these wonderful dreams come from a special material - graphene.
"Graphene is a nanomaterial with graphite as raw material. It is the lightest, thinnest and hardest ductile material among the known materials in the world so far. It has high electrical conductivity, high strength, high thermal conductivity, high specific surface area, etc. This extraordinary new material will surely bring revolutionary changes in many fields such as electric vehicles and electronic information, and is expected to become the next trillion-level industry. 5 hours to 30 minutes of subversion
Crack the bottleneck of lithium battery charging and set off a revolution in the field of electric vehicles
It only takes 5 hours to charge and can travel 500 kilometers. At the beginning of this year, the launch of Tesla can be described as "a fire in winter", setting off a revolution in the field of electric vehicles.
Although the battery technology has taken a big step forward, there is still the embarrassment of running for a while and needing to stop and charge for 5 hours. The long charging time is still an insurmountable gap for lithium batteries. Electric vehicles, which are regarded as the future development direction of automobiles, have been stagnant on the road of promotion for many years because they cannot solve this bottleneck problem.
"This door will be opened by graphene." Many industry experts are very optimistic about the application of graphene in the energy field, and the scientific research team is developing graphene-based supercapacitors and batteries. Once the graphene battery comes out, it is expected to increase the battery capacity by 1.5 times and shorten the charging time to tens of minutes. Using graphene-based supercapacitors to replace batteries, the charging and discharging time can be as short as a few seconds.
"This also means that charging electric vehicles will take less time than refueling in the future, which will bring a subversive revolution to the field of electric vehicles." They are currently laying out a graphene-based capacitor battery production line, which is expected to be launched by the end of December this year. Officially put into operation.
At the Tangshan production base, the reporter experienced the "magic" of graphene - although it comes from the same source as graphite, it is far from the pencil lead we usually see. The graphene microchips are more like cotton-like black flocs It is as thin as a cicada's wing and as light as a feather, and only 180 grams can fill a white plastic bucket with a capacity of 50 liters.
Meng Ying explained that the reason why graphene batteries have fast charge and discharge speed and large energy storage is to take advantage of the high specific surface area and high electrical conductivity of graphene materials. The electrical conductivity of graphene materials is 10 to 100 times that of copper. If the traditional lithium battery is rapidly charged and discharged, it will inevitably lead to an increase in current, and excessive current will cause the battery to heat up, shorten its service life, and even cause an explosion. Using the properties of graphene to add it to the anode and cathode materials of lithium batteries is expected to solve this drawback.
Meng Ying explained that the working process of lithium batteries is the process of lithium ions swinging back and forth from the positive electrode to the negative electrode. Adding graphene to the positive electrode material can improve the conductivity of the positive electrode material, increase the discharge rate of the battery, and speed up the charging and discharging speed of the battery. Adding graphene to the anode material can improve the ability to accommodate lithium ions and increase the storage capacity.
"The sensation of graphene is because it has created many records. A series of mysterious specialties of graphene make people full of fantasy about its application." Meng Ying described that graphene is also the thinnest and strongest material in the world. Only 0.34 nanometers thick, the thickness of 200,000 layers of graphene superimposed is roughly equal to the diameter of a human hair. It is harder than diamond and 100 times stronger than the best steel in the world. The material is almost completely transparent, with a light transmittance of over 97%, and is expected to be used to manufacture a new generation of high-performance electronic devices.
Graphene has extremely broad application potential in the fields of electronics, aerospace, special, new energy, new materials, etc. With its excellent electrical properties, graphene will be the most potential new material to replace silicon to make ultra-miniature transistors. The operating speed is expected to increase by 10 to 100 times; its light and tough characteristics are the first choice for making ultra-light body armor and ultra-light aircraft materials; using nanotechnology, graphene can also be made into a DNA sensor to detect The rotation and positional structure of DNA chains open up a new path for genome sequencing technology; graphene can also be made into antibacterial materials, which can sterilize cells without damaging cells.
1 gram to 500 ton breakthrough
Graphite flakes peel off graphene micro-flakes, defeating industrialization stumbling blocks
So, how can graphite become graphene? "Because of the weak force between graphite sheets, most of our common graphenes are exfoliated from graphite sheets." Meng Ying said that the method of sticking graphene with tape is obviously not suitable for industrial production. At present, there are mainly chemical vapor deposition, redox, pyrolysis silicon carbide and other graphene batch preparation technologies in the industry, but only a few companies in the world can carry out industrial production.
Since knowing graphene in 2009, Meng Ying has been trying to find out why the existing preparation technology cannot be mass-produced. After several years of research, his team developed an original approach based on the redox method, made changes to the existing preparation technology, and designed production processes and equipment with independent intellectual property rights, making mass production a reality.
He took a stack of A4 paper and introduced an analogy: "The graphite block has a layered structure like this stack of paper. After the previous processing method, the distance between the paper and the paper can be increased, but each sheet of paper has a layered structure. It will also be close to the upper and lower layers of paper, and it is difficult to peel off from a stack of paper. In this way, some sheets are next to each other, and some dozens of sheets are next to each other, and the probability of forming microchips with less than 5 layers is very small. "
Once the root cause is found, the problem is solved. "The key is to spread each piece of paper evenly from the stack." Meng Ying said, for example, if it was cut with a knife, the new process is more like placing "dynamite" between each piece of paper ", all "dynamite" will work together at the same time, so that a stack of paper will be evenly blasted into scattered sheets.
"If the blasted pieces of paper are too close together, they will reunite, and all previous efforts will be lost." Meng Ying said that this problem can be solved through chemical and physical methods, so that each small piece of paper will lose its reunion. performance, becoming independent individuals, unable to reunite no matter how close they are.
In this regard, Meng Ying has a deep feeling: "It sounds like a very simple reason. In order to achieve a breakthrough in production from 1 gram to 500 tons, we have updated the production process for eight generations in five years. To achieve better layering As a result, the material selection and equipment shaping involved in each step of the process route will be tested hundreds of times like Shennong tastes all kinds of herbs."
800 yuan to 25 yuan reduction
From the price of gold to the price of cabbage, the quality of gold is still maintained
"What we have to do is to try to reduce the price of graphene from the price of gold to the price of cabbage, but still maintain the quality of gold." Meng Ying said that only by reducing the production cost can graphene be more widely used in various fields, otherwise Graphene will not be able to achieve industrial applications. "For example, graphene batteries are really good, but if the price is dozens of times that of lithium batteries, no matter how excellent the performance is, who will choose to buy them?"
"After the completion of the 100-ton annual production line at the end of May, the cost of our graphene chips will be reduced to 25 yuan per gram, which is far lower than the market price of 800 yuan per gram." Meng Ying believes that the significant cost reduction, It will give graphene a cost advantage to participate in market competition.
How can the cost of graphene be reduced? "Cost reduction is mainly achieved through technological improvement." Meng Ying said that if you want to achieve an annual output of hundreds of tons, only one production line can achieve it, and according to the original technology, tens of thousands of optical equipment are needed. It is necessary to invest billions of funds, not to mention the cost of equipment depreciation and personnel salaries. In addition, the selection of raw materials also plays an important role in reducing costs by replacing tens of thousands of dollars with raw materials of several hundred dollars.
Taking the 18650 battery used in Tesla electric vehicles as an example, he said that at 25 yuan per gram of graphene, each battery requires about 1.2 grams of graphene, and the cost is 30 yuan, which is not too different from the price of ordinary lithium batteries. big. However, the lifespan of a graphene battery is 10,000 times, which is 10 times that of a traditional battery. Only 10 traditional batteries can equal the lifespan of one graphene battery. Based on this, the price of a graphene battery is lower.
"The cost of 25 yuan is far from reaching the cost limit. With the increase in the depth of research and development and the improvement of the preparation process, the cost will be lower and lower. Our goal is a few yuan per gram or even lower." Meng Ying is sober about this. The lower the price of graphene, the greater the demand, and the increase in demand will also promote the expansion of the scale of the industry, which is a virtuous circle.
"While reducing costs, we must also ensure the quality of graphene, so that graphene materials will be more valuable." Meng Ying explained that the specific surface area is an important criterion for evaluating the quality of graphene products. Large, the higher the single layer rate, the better the quality.
The instability of graphene quality will also affect the performance stability of downstream industry chain products. Meng Ying said, "For example, the specific surface area of different batches of graphene is quite different. If a graphene battery is made, some of the capacity is 1.1 times that of ordinary lithium batteries, some are 1.3 times, and some are even more. In application It will affect the performance of the electric vehicle.”
"The specific surface area of graphene primary products produced by our technology is stable at about 550 square meters per gram, and the highest pilot test results can reach about 1,000 square meters." According to Meng Ying, by controlling the quality of raw materials and production processes, the The number of graphene layers produced by the company is kept stable below 5 layers.