Is the electric car fully charged in just one minute?

A substance that seems to be out of bounds with the battery has become the key to breaking through the bottleneck of battery technology. Researchers at Nanotek Instruments, Inc., USA, have developed a new type of energy storage device that uses lithium ions to quickly shuttle a large amount of motion between the graphene surface and the electrode, reducing the time it takes to charge a battery from a few hours to less than a minute. The research was published in a recent issue of nano letters.

Battery charging performance becomes the biggest challenge for electric vehicle development

As we all know, electric vehicles are regarded as the future development direction of automobiles because of their clean and energy-saving characteristics, but the main technical bottleneck facing the development of electric vehicles is battery technology. This is mainly manifested in the following aspects: First, the energy storage density of the battery refers to the amount of energy stored in a certain space or mass material, and the problem to be solved is how far the electric vehicle is charged once. The second is the charging performance of the battery. People hope that electric vehicle charging can be completed in a few minutes like refueling, but the time-consuming problem is always an obstacle that is difficult to overcome by battery technology. The hours of charging time often put off many people interested in electric cars. Therefore, some people refer to the charging performance of electric vehicle batteries as the real bottleneck in the development of electric vehicles.

At present, lithium battery and super capacitor technology are mainly used in battery technology, and lithium batteries and super capacitors have different lengths. Lithium-ion batteries have a high energy storage density of 120 watts/kg to 150 watts/kg, and super capacitors have a low energy storage density of 5 watts/kg. However, lithium batteries have a low power density of 1 kW/kg, while super capacitors have a power density of 10kW/kg. A large amount of research work is currently focused on improving the power density of lithium-ion batteries or increasing the energy storage density of super capacitors, but the challenges are enormous.

The new study bypasses the challenge by using the magical material of graphene. Graphene has become the first choice for new energy storage equipment because it has the following characteristics: it is the material with the highest conductivity, which is five times higher than copper; it has strong heat dissipation capacity; low density, four times lower than copper, and lighter weight. When the surface area is twice that of carbon nanotubes, the strength exceeds that of steel; the ultra-high Young's modulus and the highest intrinsic strength; the specific surface area (that is, the total area per unit mass of material) is high; the displacement reaction is not easy to occur.

New equipment makes electric cars fully charged in less than 1 minute

The new energy storage device, also known as the graphene surface lithium ion exchange battery, or simply the surface-mediated battery (SMCS), combines the advantages of lithium batteries and super capacitors, while combining high power density and high energy storage density. . Although current energy storage equipment has not yet adopted optimized materials and structures, its performance has surpassed that of lithium-ion batteries and super capacitors. The power density of the new device (ie, the maximum power output from the battery divided by the weight or volume of the entire fuel cell system) is 100 kW/kg, which is 100 times higher than commercial lithium-ion batteries and 10 times higher than super-capacitors. The power density is high, the energy transfer rate is high, and the charging time is shortened. In addition, the new battery has an energy storage density of 160 watts/kg, which is comparable to commercial lithium-ion batteries and is 30 times higher than conventional super capacitors. The greater the energy storage density, the more energy is stored.

The key to SMC is its very large graphene surface at its cathode and anode. When making batteries, the researchers placed lithium metal on the anode. At the first discharge, lithium metal is ionized and migrates to the cathode through the electrolyte. The ions pass through the small holes in the surface of the graphene and reach the cathode. During the charging process, due to the large surface area of the graphene electrode, a large amount of lithium ions can rapidly migrate from the cathode to the anode to form a high power density and a high energy density. The researchers explained that the exchange of lithium ions on the surface of the porous electrode can eliminate the time required for the intercalation process. In the study, the researchers prepared various types of graphene materials such as graphene oxide, single-layer graphene and multilayer graphene to optimize the material configuration of the device. The next step will be to focus on the cycle life of the battery. The current research shows that after charging 1000 times, 95% of the capacity can be retained; after charging 2000 times, no crystal structure has been found. The researchers also plan to explore the impact of different lithium storage mechanisms on device performance.

Studies have shown that under the same weight, only the lithium battery is replaced by the SMC that has not been optimized, and the driving distance of the SMC or lithium-ion battery electric vehicle is the same, but the charging time of the SMC is less than one minute, while the lithium ion battery needs to be counted hour. Researchers believe that the performance of SMC will be better after optimization.

If the electric car is widely popular in the future, the charging station is set at the gas station, and the result will be a very interesting scene, that is, the charging time of the electric car will be faster than the refueling, and it is cheaper than refueling. The researchers said that in addition to electric vehicles, the equipment can also be used for renewable energy storage (such as storage of solar and wind energy) and smart grid.

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