Academicians of the Chinese Academy of Sciences angrily criticize “new” graphene batteries. What’s the reason?

In the past two days, the news that Ouyang Minggao, an academician of the Chinese Academy of Sciences, angrily criticized the exaggerated propaganda of GAC New Energy Vehicles has once again brought this magical and magical material? Graphene back to the attention of netizens.

As usual, let us first sort out the ins and outs of this matter for the missionaries.

At an electric vehicle forum held last Saturday, Ouyang Minggao, an academician of the Chinese Academy of Sciences, publicly stated: "If someone tells you that this car can run 1,000 kilometers and be fully charged in a few minutes, it is safe and cost-effective." Very low again. Judging from current technology, he must be a liar. ?

Coincidentally, on the poster for GAC’s Eian press conference last Friday, a huge slogan showed GAC’s big muscles in the battery field: The electric car we are about to release is amazing. , 80% full charge in 8 minutes, and the battery life reaches 1,000 kilometers.

This matter suddenly became interesting. At the press conference held by GAC on Friday, Academician Ouyang made such a speech on Saturday. . .

In fact, if we think about it briefly, we know that GAC’s publicity is impossible.

If you want to charge a battery with a range of 1,000 kilometers in 8 minutes, the State Grid is the first to refuse.

The bad reviewer simply calculated the calculation for the poor friend. Now 80% of the 1000 kilometers of the electric car in 8 minutes, the power required for charging is about 900 kilowatts. If a common charging pile is used with 380 V DC The voltage and current must reach 2400 A.

The current fast charging piles of the State Grid can only support 30 kilowatts at most. To say the least, even if a charging pile supporting 900 kilowatts is built, you cannot charge an electric car. The entire community was completely without power. . .

Some friends would like to ask, aside from the issue of power, is this graphene battery possible that can be charged to 80% in 8 minutes and has a battery life of 1,000 kilometers?

It is estimated that many missionaries still haven’t figured out what graphene is. Is graphene really so magical?

Those who have studied junior high school chemistry should all know that among chemical elements there is a type of allotrope. They are all composed of a single element, but because of the way they are arranged, Different, but with completely different characteristics.

Graphene, diamond, graphite and fullerene are all allotropes of the carbon element.

As we all know, we live in a three-dimensional space, and before the emergence of graphene, all known elements also existed in a three-dimensional structure.

The structure of graphene is surprisingly weird. To put it bluntly, it is a single layer of graphite, a material that exists in a two-dimensional space.

In fact, the discovery of graphene is far simpler than the friends imagined. These two scientists used an extremely simple tool: tape!

They attached tape to the surface of graphite, and then peeled off the tape again and again to obtain a single-layer graphite structure.

So the magical material graphene, which has been demonized by these unscrupulous manufacturers in recent years, is far from being as mysterious as everyone imagines.

However, due to graphene’s unique two-dimensional structure, it has become a material of great value.

First of all, it is unimaginably light but extremely strong. Its strength is 300 times that of steel, but it has good flexibility.

And graphene is also an almost perfect thermal conductivity material, with a thermal conductivity as high as 3000-5000 W/m?K. This value can kill the thermal conductivity of almost all metals.

In addition, due to the special structure of graphene, it has a very high electron mobility, that is, electrons can move freely on graphene if they enter uninhabited territory, so the conductivity of graphene is also very good. The fever is still small.

With so many outstanding properties appearing in one material, graphene has instantly become a favorite among major manufacturers and materials research fields.

The discovery of graphene also naturally won the Nobel Prize in Physics.

After learning about graphene, we can easily think that using graphene’s high conductivity can indeed greatly improve the charging speed.

Yes, the idea is wonderful.

Unfortunately, graphene is too expensive.

If you tear it off with tape, you can indeed get observable graphene. But if you want to get usable graphene, you may not be able to stick it on tape. You have to use chemical oxidation, crystal epitaxial growth, chemical vapor deposition, etc. to prepare it.

But graphene is a two-dimensional material that is prone to wrinkles and deformation. Once deformed, the various properties of graphene will change. Therefore, the cost of good graphene has not been reduced, and it is known as ?Black gold?.

On the other hand, the surface properties of graphene are greatly affected by the chemical state. It is difficult to maintain the stability of each batch of graphene. In addition, the cycle life of pure graphene is low, which are all problems.

Therefore, in current actual use, graphene in graphene batteries often appears as a dopant of electrode materials. It would be good to slightly improve the conduction and heat dissipation problems.

We are still far away from completely breaking through the bottleneck of today’s batteries.

Just like the major mobile phone manufacturers have long known that graphene batteries are a hot commodity, they have made plans very early, and after several years of investment, none of them have been able to produce mass-produced products.

Is graphene really useless? No, it’s because low-cost graphene batteries are useless, and useful graphene batteries are too expensive to make and can only be used in laboratories.