Advantages and disadvantages of graphene batteries

Graphene is a honeycomb planar film formed by sp2 hybridization of carbon atoms. It is a quasi-two-dimensional material with only one atomic layer thickness, so it is also called monoatomic layer graphite. It has a thickness of about 0.335 nm and has different undulations depending on the preparation method, usually about 1 nm in the vertical direction and about 10 nm to 25 nm in the horizontal direction. It is all carbon crystals other than diamond (zero-dimensional fullerene). The basic structural unit of one-dimensional carbon nanotubes, three-dimensional body-oriented graphite.

Among them, the application of graphene in the energy field is the hottest and the most promising direction. In principle, as an excellent two-dimensional conductive material, graphene is added to the positive electrode material of lithium ion battery (lithium iron phosphate, etc.), which can improve the conductivity of the electrode material, and can also encapsulate the positive electrode nanoparticles. Upgrade of "carbon black + carbon nanotube" conductive agent.

Lithium batteries with graphene conductive agents have different rates of performance, consistency and longevity (this is an advantage).

In addition, graphene can also be added to new anode materials (mesophase carbon microspheres, etc.) to enhance the performance of the electrode material, which is also a possibility for future development.

Although these applications are not the core technology of lithium batteries, they have not greatly improved the capacity and density of lithium batteries, but they can improve the comprehensive performance of battery packs and even new energy vehicles, which is a relatively high technical maturity of graphene applications. .

Graphene battery, a new energy battery developed by utilizing the characteristics of rapid ion transport of lithium ions between the surface of the graphene and the electrode.

The basic principle of graphene battery: the relationship between time (hours, days) and voltage generation of graphene battery in saturated copper chloride solution.

The experimentally fabricated circuit contained LEDs that were connected to ribbon graphene by wires. They simply placed graphene in a copper chloride solution for observation. The LED light is on. In fact, they need six graphene circuits to form a series, so that the required 2V can be generated, and the LED light can be illuminated to get the picture.

Xu Zihan and colleagues said that the occurrence here is that copper ions have a double positive charge, and the speed of passing through the solution is about 300 meters per second because of the thermal energy of the solution at room temperature. When an ion violently strikes a graphene ribbon, the collision produces enough energy to cause the electrons that are not in the field to leave the graphene. There are two choices for electrons: you can leave the graphene band, combine with copper ions, or pass through graphene to enter the circuit.

It turns out that flowing electrons are faster in graphene than they pass through the solution, so the electrons naturally choose the path through the circuit. It is this that illuminates the LED lights "the electrons released tend to pass through the graphene surface rather than entering the electrolyte. The device produces voltage like this," Xu Zihan said.

Therefore, the energy generated by this device comes from the heat of the surrounding environment. They can increase the current, just heat the solution, or use ultrasonic waves to accelerate the copper ions. By relying on the surrounding heat, they can keep their graphene batteries running for 20 days. However, there is an important question mark. Another assumption is that a chemical reaction produces electricity, just like a normal battery.

However, Xu Zihan and colleagues said that they ruled out this because several sets of control experiments were conducted. However, these are introduced in some supplemental materials that do not seem to be on the arXiv website. They need to be open before someone else makes a serious statement. From the perspective of surface value, this seems to be a very important outcome. Others also generate overcurrents in graphene, but only let water flow through it, so this is not really surprising, and moving ions can also produce this effect. This heralds a clean green battery that relies solely on ambient heat. Xu Zihan and colleagues said: "This represents a huge breakthrough, the study is self-driven technology."

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advantage:

1) The storage capacity is three times that of the best products in the market. A lithium battery (whichever is the most advanced) has a specific energy value of 180 wh/kg, while a graphene battery has a specific energy of more than 600 wh/kg.

2) An electric vehicle that uses this battery to supply electricity can travel up to 1000 kilometers, and its charging time is less than 8 minutes.

3) Long service life. Its service life is four times that of a conventional hydrogen battery and twice that of a lithium battery.

4) Light weight. The properties of graphene allow the weight of the battery to be reduced to half that of conventional batteries, which increases the efficiency of the machine in which the battery is loaded.

5) Low cost. The company that produces the battery says its cost will be 77% lower than lithium batteries. ”

"Stable high, long battery life, fast charging speed;

Disadvantages:

Traditional conductive carbon/graphite is very cheap, and it is sold on tons, while graphene is too expensive. One gram of thousands of prices, this is not something that ordinary companies can afford. A few years ago, the price of graphene was as high as 5,000 yuan per gram, far exceeding the price of gold, and ordinary consumers are also unbearable.

Xiaobian Conclusion: The above content is from the network, but I am not optimistic. For many things, most people prefer false hopes and no cruel truths. I never reject imagination. This is also an important driving force for the advancement of human society. But you can't expect this thing to be omnipotent. If you put it in, you can promote the development of an industry. Or else you use Internet thinking to give me a battery test? The development of battery technology is indeed slow, which requires us all to work together to do things well, instead of pointing to the gimmicks every day to solve problems in life. Look at the kind of craftsmanship in Japan that makes batteries, which is always worth learning. Anyway, the individual is not optimistic.