How graphene lithium batteries work, how graphene batteries work

The content is as follows: a new energy battery is developed by taking advantage of the rapid and large amount of shuttle movement of lithium ions between the graphene surface and the electrode. The relationship between time (hours, days) and voltage generated by graphene batteries in saturated copper chloride solution.

The technological breakthrough of micro graphene ultracapacitor can be said to be a revolutionary development for batteries. At present, the main method of manufacturing miniature capacitors is plate printing technology, which requires a lot of manpower and cost, and hinders the commercial application of the products. Now you can make more than 100 tiny graphene supercapacitors on a single disc in 30 minutes, using cheap materials, from a standard DVD burner or even at home.

Experiments on self-charging of graphene batteries using ambient heat

The relationship between time (hours, days) and voltage generated by graphene batteries in saturated copper chloride solution.

The resulting circuit contains leds, which are wired to ribbon graphene. They just put graphene on copper chloride (copperchloride), in the solution. The LED is on. In fact, they needed six graphene circuits, in series, to produce the required 2V, to make the LED light shine, to get this picture.

What's happening here, xu and his colleagues say, is that copper ions, which have a double positive charge, are moving through the solution about 300 meters per second because of the heat energy of the solution at room temperature. When the ions slam into the graphene belt, the collision generates enough energy to keep electrons out of the graphene. Electrons have two options: they can leave the graphene band and bond to copper ions, or they can pass through the graphene and enter the circuit.

It turns out that the electrons are flowing faster in graphene than they are going through the solution, so the electrons will naturally take a path through the circuit. It's this small amount of light that makes LED lights "release electrons that are more likely to pass through the graphene surface than into the electrolyte. This is how the device generates the voltage, "Xu said.

As a result, the energy generated by the device comes from the heat of the surrounding environment. They can increase the current simply by heating the solution, or speed up the copper ions with ultrasound. Using only ambient heat, they were able to keep their graphene batteries running for 20 days. But there is an important question mark. Another hypothesis is that some chemical reaction produces an electric current, just like a normal battery.

However, xu and his colleagues said they ruled this out because they conducted several controlled experiments. However, these are introduced in some supplementary material and they do not appear to be on the arXiv website. They need to go public before anyone else makes a serious statement. On the face of it, this looks like a very important achievement. Other people have also created currents in graphene, but just let the water flow through it, so it's not really surprising that moving ions can have this effect. This foreshadows clean, green batteries, powered only by ambient heat. "" this represents a huge breakthrough in the study of self-driven technologies," "xu and colleagues said.

Popularize science:

1. Graphene batteries are just a way of saying that they are lithium batteries or other dielectric batteries.

Graphene is a super-thin material that cannot store electricity on its own. It is mainly used to separate the materials at the two poles of a battery, so electrons can pass through it very easily. In other words, the internal resistance of the battery is very small, which is why it is charged so quickly.

3. With the above knowledge, you will know that for a graphene battery of the same size, its capacity will not have much advantage, or even disadvantage, because you need to design a fast-charging circuit. Therefore, it is impossible to use a graphene battery for 10 days and half a month, with the exception of some abnormal designs!

4. The main advantages of graphene batteries lie in their service life and charging speed. After test, graphene battery charge and discharge 2000 times attenuation rate within 15%, about 40 ~ 80% compared with the normal lithium battery, charging speed 5000 mah can full of half an hour, if the circuit design, right in theory can be filled within 5 seconds, but the bottleneck of charging speed is not the battery itself, but in the charger and cable, to reach so high power, the power transmission lines is a big test.

Do not understand the misleading people... Can baidu encyclopedia: graphene battery

1) graphene has a very large specific surface area (2630m2/g), which can reduce the battery polarization, thus reducing the energy loss caused by polarization.

2) graphene has excellent electrical and thermal conductivity, that is, it has a good electronic transmission channel and stability.

3) the scale of graphene sheet layer is at the nano-micro level, which is much smaller than that of bulk graphite, which reduces the diffusion path of Li+ between graphene sheets. The increase of lamellar spacing is also beneficial to the diffusion transmission of Li+ and the improvement of power performance of lithium ion batteries.

How does a graphene battery work? Application of graphene in anode materials for lithium ion batteries

The application and advantages of graphene in lithium anode and cathode electrode materials are summarized below.

1. Application of graphene in anode materials of lithium ion batteries

Graphene is directly used as the cathode material for lithium ion batteries

Advantages of graphene direct lithium storage: 1) high specific capacity: lithium ions have non-stoichiometric embedding in graphene? Detachable, specific capacity up to 700~2000mAh/g; 2) high charging and discharging rate: the distance between layers of multi-layer graphene materials is significantly greater than the distance between layers of graphite, which is more conducive to the rapid embedding and de-embedding of lithium ions. Most studies have also shown that the capacity of the graphene negative electrode is about 540mA·h/g. However, due to the decomposition of a large number of oxygen-containing groups on its surface or the reaction with Li+ during the charging and discharging process, the battery capacity is attenuated, and its multiplier performance is also greatly affected.

Defects caused by heteroatom doping will change the surface morphology of graphene anode material, thus improving the wettability between electrode and electrolyte, shortening the distance of electron transfer within the electrode, and improving the diffusion and transfer speed of Li+ in the electrode material, so as to improve the conductivity and thermal stability of the electrode material. For example, doped N and B atoms can deform the structure of graphene (FIG. 1), and charge and discharge at 50mA/g magnification with a capacity of 1540mAh/g, and the graphene material doped with N and B can be charged and discharged rapidly in a relatively short time, and the charge and discharge time of the battery is 30s at 25A/g magnification [2].

How does a graphene battery work? Application of graphene in anode materials for lithium ion batteries

However, there are still some disadvantages for graphene materials to be directly used as the negative electrode of batteries, including: 1) monolayer graphene sheets prepared are easy to accumulate, and some high lithium storage space is lost due to the reduction of specific surface area; 2) low coulomb efficiency for the first time, generally less than 70%. Due to the large specific surface area and abundant functional groups, electrolytes will decompose on the graphene surface during the cycle, forming SEI film. At the same time, the residual oxygen-containing groups on the surface of carbon materials have irreversible side reactions with lithium ions, resulting in further decrease of reversible capacity. 3) fast initial capacity attenuation; 4) voltage platform and voltage lag. Therefore, in order to solve this series of problems, graphene and other materials are compounded to make graphene-based composite anode materials, which have become a hot topic in lithium battery research and a direction of development of lithium anode materials.

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