brief introduction
Supercells are composed of carbon layers with a thickness of one atom. This technology can quickly charge mobile phones and cars in the shortest time, and can be easily manufactured and integrated into devices, and it is expected to manufacture smaller mobile phones in the future.
manufacture
In order to develop this kind of micro supercapacitor, the researchers used a two-dimensional graphene layer, which is only a single atom thick in the third dimension.
Super battery
Because the traditional method of manufacturing micro supercapacitors involves intensive lithography technology, it is proved that it is difficult to manufacture low-cost devices, so its commercial application is limited.
However, based on the technology of writing DVD at the speed of light suitable for the public, researchers can manufacture graphene micro supercapacitors at only a part of the cost of traditional devices.
Using this technology, more than 65,438+000 miniature super batteries can be manufactured on a CD with cheap materials in less than 30 minutes.
Functional characteristics
In order to make the super battery more efficient, two separate electrodes must be placed in a way that maximizes its surface area, which will enable the super battery to store more electric energy.
In the past, miniature batteries were made of layers of graphene stacked together as electrodes, just like sandwich bread slices. But in supercapacitors, researchers use a cross model (similar to a twisted finger) to arrange electrodes side by side. This will help to maximize the surface area of the two electrodes, although it will also reduce the path that ions in the electrolyte need to diffuse.
prospect
Super battery can store more electric energy and complete charging faster. Researchers say that in the future, people may complete the manufacture of this super battery at home.
However, Richard Kahn, a professor in the Department of Materials Science and Engineering at UCLA, said that there are challenges in the design and manufacture of integrated electronic circuit energy storage units.
In life, the lack of battery capacity often plagues users of electric vehicles and smart phones. The super battery with stable performance and reasonable price has been the dream of human beings for many years. At present, people's image description of the super battery can be summarized as: once charged, the electric car can travel 1000 km, and the smart phone can play for one week. The charging time can be controlled within a few minutes, preferably wireless charging. The market size of this super battery is not less than 1 trillion dollars. At present, the United States, China, Japan and South Korea are all competing for super batteries.
At present, the commonly used lithium-ion batteries began to be commercialized after 199 1 year. There are three main types: lithium cobaltate, lithium ferrous phosphate and lithium manganate. Lithium cobalt oxide battery has the highest energy density, but it is unstable at high temperature, and the other two energy densities are not high. The fifth generation product of rechargeable battery-lithium metal battery was born in 1996, which is superior to lithium ion battery in safety, specific capacity, self-discharge rate and cost performance. But there is still a big gap from the requirements of super batteries.
Graphene is expected to trigger a new breakthrough in batteries. Graphene, which was born in 2004, is characterized by its good electrical and thermal conductivity: as an electrical conductor, its electrical conductivity can be comparable to that of metallic copper; As a heat conductor, it is the best of the existing materials, and what is more commendable is that this material still has high hardness under very thin conditions. Graphene has been listed as an important material in major industrial countries for further development. At present, the application research of graphene in batteries basically has three directions:
First, graphene is used to form new system batteries. In other words, using graphene to make a new system of batteries is subversive in performance and is called "super battery". The energy density of the battery made of this material exceeds 600wh/kg, which is five times that of the current power lithium battery. It only takes 8 minutes to charge once, and it can travel 1000 km. The weight of the battery is only half that of the lithium-ion battery, and the volume will be greatly reduced, thus reducing the weight of the car using the battery; The battery life is longer, which is 4 times that of traditional hydrogenated battery and 2 times that of lithium battery; Its cost will be reduced by 77% compared with the current lithium battery. These physical parameters meet the requirements of super battery.
The second is to strengthen the performance of existing batteries with graphene. Graphene is applied to existing batteries to improve the performance of lithium batteries, solar batteries and other batteries, and strive to achieve the performance of super batteries. For those enterprises that have invested heavily in building lithium battery factories, it is difficult to invest in developing a brand-new battery in a short period of time. It may be more realistic to use the characteristics of graphene to improve the performance of existing lithium batteries. As far as the properties of graphene are concerned, graphene, as the thinnest, hardest, conductive and flexible nano-material, can be widely used in energy storage products such as lithium-ion batteries, supercapacitors and solar cells. The special structure of graphene determines that it can improve the performance of lithium ions in batteries to obtain high-rate channels, which can help lithium battery technology break through long-term insurmountable obstacles. At present, the mobile phone battery developed with graphene and silicon as raw materials can run for one week in 15 minutes at a time.
Thirdly, graphene is used to catalyze the performance of fuel cells. A special graphene material is used as a catalyst instead of platinum to produce hydrogen fuel for fuel cells. Fuel cell is a kind of power generation device that directly converts the chemical energy of fuel into electric energy. Compared with other batteries, it has the advantages of high energy conversion efficiency and no environmental pollution. Proton conducting membrane is the core part of fuel cell technology. Fuel leakage often exists on the existing proton membrane, which reduces the effectiveness of the battery. However, protons can easily "cross" two-dimensional materials such as graphene, while other substances are difficult to cross, which can solve the problem of fuel penetration and improve the performance of the battery.
The application of graphene technology is still in the primary stage, especially the single-layer graphene material, which can greatly reduce the volume and weight of the battery, but the yield is low and the production cost is high, which has become an important reason why the industrialization of graphene batteries is difficult. Therefore, further innovation, technology improvement and production cost reduction are the keys to the future development of graphene batteries. At present, China is in the forefront of the world in the research and development and application of graphene, and a number of graphene batteries and graphene lithium-sulfur batteries have made breakthrough progress.
Of course, the global research and development in the field of batteries is not limited to graphene, and Japan is developing and using magnesium to produce batteries with higher performance and lower cost; Sweden is studying the use of carbon fiber to improve the performance of lithium batteries. However, these new technologies need to be baptized by the market if they want to be truly practical and even form a huge industry.
In short, the process of finding super batteries is a process of technological innovation and industrial structure optimization. The breakthrough of the super battery represented by graphene will be the time when all the electric drive devices including new self-driving planes, electric cars, mobile phones and computers are transformed, which will have subversive significance for many industries and will surely turn a new page for human life.