Break through the "fatal defect" of lithium batteries

Sep 18, 2019   Pageview:35

The world's third 100-ton graphene production line will be put into production in our province at the end of May. It will trigger a revolution in the field of electric vehicles.

 

Maybe one day, you will put the touch-screen tablet in three folds and two stacks into the pocket; use a few seconds to fully charge the phone, do not recharge in the first half of the month; ride an ultra-light aircraft, drive a light car, or even board tens of thousands of miles of space elevators that in human dream.

 

All these wonderful dreams come from a special material - graphene.

 

“Graphite is a nano material made of graphite. It is the lightest, thinnest and hardest tough material in the world. It has high conductivity, high strength, high thermal conductivity, high specific surface area, etc. characteristics." On April 2, Ying Meng, president of Tangshan Jianhua Industrial Group, which has long been concerned about the development of graphene, said that this extraordinary new material will bring revolutionary changes in many fields such as electric vehicles and electronic information. It is expected to become the next trillion-level industry.

 

“We have pioneered the development of a new method for preparing graphene, which is suitable for low-cost mass production.” Since the end of last year, Jianhua Industrial has produced an annual output of 500,000 grams of graphene production line in our province. The 100-ton production line is under intense assembly and will be officially put into operation at the end of May. For this exciting new breakthrough in graphene mass production technology, Ying Meng feels that it will bring huge space for the development of new industrialization.

 

5 to 30 minutes of subversion

 

Crack the bottleneck of lithium battery charging and set off a revolution in electric vehicles

 

Charging can take 500 kilometers in just 5 hours. At the beginning of this year, the listing of Tras in China can be described as "a fire in the winter", setting off a revolution in the field of electric vehicles.

 

Although battery technology has taken a big step forward, there is still a knack for running for a while and charging for 5 hours. The long charging time is still an insurmountable gap for lithium batteries. Electric vehicles, which are regarded as the future direction of the automobile, have been unable to solve this bottleneck problem and have been on the road of promotion for many years.

 

“This door will be opened by graphene.” Like many industry experts, Ying Meng is very optimistic about the application of graphene in the energy field. The company's research team is working on the development of graphene-based super capacitors and batteries. Once the graphene battery is available, it is expected to increase the battery capacity by 1.5 times and the charging time to tens of minutes. Using a graphene-based super capacitor instead of a battery, the charge and discharge time can be as short as a few seconds.

 

"This means that charging electric vehicles in the future is shorter than refueling time, which will bring a disruptive revolution in the electric vehicle field." Ying Meng said that they are currently laying out a graphene-based capacitor battery production line, which is expected to be It was officially put into operation at the end of December this year.

 

At the production base of Tangshan Jianhua Industrial Group, the reporter experienced the “magic” of graphene – although it is the same source as graphite, it is far from the pencil core we usually see. The graphene microchip is more like cotton. Black floc, which is as thin as a flap and light, can only fill a white plastic bucket with a capacity of 50 liters in just 180 grams.

 

Ying Meng explained that the reason why the graphene battery has fast charge and discharge speed and large energy storage is to utilize the high specific surface area and high conductivity of the graphene material. The conductivity of the graphene material is 10 to 100 times that of copper. If the traditional lithium battery is charged and discharged quickly, it will inevitably lead to an increase in current, and the current will cause the battery to heat up, shorten the service life, and even cause an explosion. The use of graphene to add it to the positive and negative materials of lithium batteries is expected to solve this drawback.

 

Ying Meng explained that the working process of lithium batteries is the process of lithium ions oscillating 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 accelerate the charge and discharge rate of the battery. Adding graphene to the negative electrode material can increase the capacity to accommodate lithium ions and increase the storage capacity.

 

“The sensation of graphene is because it has created many records. The mysterious speciality of graphene makes people full of illusions about its application.” Ying Meng describes that graphene is still the thinnest and strongest material in the world. Only 0.34 nm thick, the thickness of 200,000 layers of graphene is approximately equal to the diameter of a hair strand. It is harder than diamonds and is 100 times stronger than the best steel in the world. The material is almost completely transparent and has a light transmittance of over 97%, which is expected to be used in the manufacture of a new generation of high-performance electronic devices.

 

At present, the team of nearly 40 people of the company is working on the development and application of the graphene downstream industrial chain, and at the same time, there are more than ten products. According to reports, graphene has unparalleled potential in the fields of electronics, aerospace, military, new energy, new materials, etc.: With the excellent electrical properties of graphene, it will be the new material that has the potential to replace silicon to make ultra-micro transistors. In the future, the speed of computers 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 be made into a DNA sensor. It is used to detect the rotation and positional structure of DNA strands, opening up a new path for genome sequencing technology; graphene can also be made into antibacterial materials, while sterilizing without damaging cells.

 

1 to 500 tons of breakthroughs

 

Graphite sheets peel off graphene microchips and defeat industrialization

 

At the beginning of March this year, I went to Guangdong to discuss cooperation with a battery company for the first time. Ying Meng only used a barrel of 180 grams of graphene microchip samples to open the door of cooperation without any effort. When I saw the sample of the barrel, the person in charge of Guangdong was "stunned" at the time. I did not wait for Ying Meng to introduce it and asked for cooperation.

 

“Compared with the laboratory in units of 1 gram, this barrel sample is undoubtedly astronomical. The large-scale production capacity is the most important factor that promotes cooperation between the two parties.” Ying Meng believes that “high-quality, the low-cost macro production process is the key to the current industrialization and entry of graphene into the application field."

 

At present, Jianhua Industrial Group's annual output of graphene reaches 500,000 grams, and the graphene production line with an annual output of 100 tons will also be put into production at the end of May. The performance is among the best in the industry. At the same time, the company's second-phase production line with an annual output of 500 tons has completed the production process design work, and is planning to start construction in Caofeidian before the end of the year.

 

So how can graphite become graphene? “Because the force between the graphite sheet and the layer is weak, most of our common graphene is peeled off from the graphite sheet.” Meng Ying said that the method of sticking out graphene with tape is obviously not suitable for industrial production. At present, there are mainly graphene batch preparation technologies such as chemical vapor deposition, redox method and pyrolytic silicon carbide method, but only a few companies in the world can carry out industrial production.

 

Since the beginning of 2009, knowing graphene, Ying Meng has been trying to find out the reasons why the existing preparation technology does not produce energy. After several years of research, his team made a unique approach based on the redox method, changed the existing preparation technology, and designed the production technology and equipment with independent intellectual property rights, making mass production a reality.

 

He took a glimpse of A4 paper and said, "The graphite block has a layered structure like this crepe paper. After the previous processing method, the distance between the paper and the paper can be enlarged, but each paper It will also be close to the paper of the upper and lower layers, and it is difficult to peel off from a piece of paper. Some of them are tied together, and some of them are twisted together, and the probability of forming a microchip of 5 or less is small. ”

 

When the root cause is found, the problem is solved. “The key is to spread each piece of paper evenly from the paper.” Ying Meng said, if the original method is to cut with a knife, the new process is more like placing an explosive between each piece of paper. "All the "dynamites" will work together at the same time, so that a piece of paper will be evenly fried into pieces of scattered paper.

 

“If the blasted paper is too close, it will be reunited together, so it will be abandoned.” Ying Meng said that this problem can be solved by chemical and physical methods, so that each small piece of paper loses its reunion. Performance, become an independent individual, even if you get close, you can't reunite.

 

In this regard, Ying Meng feels good: "It sounds very simple. In order to achieve a breakthrough in production from 1 gram to 500 tons, our light preparation process has been updated for eight generations in five years. Want to achieve better stratification. The effect, the material selection and equipment setting involved in each step of the process will be tested hundreds of times like Shennong tasted the grass."

 

Reduction from 800 Yuan to 25 Yuan

 

From the price of gold to the price of cabbage, it still retains the quality of gold.

 

"What we have to do is to try to reduce graphene from the price of gold to the price of cabbage, but still retain the quality of gold." Ying Meng said that only by reducing the production cost, graphene can be more widely used in various fields. Otherwise Graphene will not be industrialized. "For example, the graphene battery is really good, but if the price is dozens of times that of the lithium battery, who will choose to buy even if the performance is excellent?"

 

“After the completion of the 100-ton production line at the end of May, the cost of graphene microchips produced by us will be reduced to 1 gram of 25 Yuan, far lower than the market price of 800 Yuan per gram.” Meng Ying believes that the cost is greatly reduced, which will make graphene have the cost advantage of participating in market competition.

 

How can the cost of graphene be reduced? “Reducing costs is mainly achieved through technological improvements.” Meng Ying said that to achieve the annual output of hundreds of tons, as long as one production line can be realized, and the original technical optical equipment will be tens of thousands, only this one. It is necessary to invest billions of dollars, not to mention equipment depreciation, staff salaries and other expenses. In addition, with hundreds of dollars of raw materials instead of tens of thousands of dollars, raw material screening also plays an important role in reducing costs.

 

He used the 18650 battery used in Tesla electric vehicles as an example. According to the calculation of 25 Yuan per gram of graphene, each battery needs about 1.2 grams of graphene, and the cost is 30 Yuan. This is not too different from the price of ordinary lithium batteries. Big. However, the life of the graphene battery is 10,000 times, which is 10 times that of the conventional battery. Ten conventional batteries can reach the service life of one graphene battery, and the price of the graphene battery is calculated to be lower.

 

"25 Yuan is far from reaching the cost limit. With the increase of research and development depth and the improvement of the preparation process, the cost will be lower and lower. Our goal is 1 gram or even lower." Ying Meng is sober. The understanding that the lower the price of graphene, the greater the demand, and the increase in demand will also promote the expansion of the industry scale, which is a virtuous circle.

 

“While reducing costs, we must also ensure the quality of graphene, so graphene materials will be more valuable.” Ying Meng explained that the specific surface area is an important criterion for evaluating the quality of graphene products. The specific surface area of graphene is larger, the higher the single layer rate, the better is the quality.

 

The instability of graphene quality will also affect the performance of downstream industrial chain products. For example, Ying Meng said, “For example, different batches of graphene have a large difference in specific surface area. If they are made into graphene batteries, then some of the capacity is 1.1 times that of ordinary lithium batteries, some are 1.3 times, and some even more. It will affect the performance of electric vehicles."

 

“The graphene primary product produced by our technology has a specific surface area of about 550 square meters per gram, and the highest test result can reach about 1000 square meters.” According to Ying Meng, by controlling raw material quality and production process, the number of graphene layers produced by the company is stable below 5 layers.

 

The page contains the contents of the machine translation.

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