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Hello everyone, today we talk about graphene batteries. In the past two days, GAC has revealed a big news, it is expected that the end of this year will be the end of this year will be the real car mass production test, GAC Aian will be the first brand to use graphene batteries.
GAC said that if the graphene battery can be mass-produced and loaded, it can be fully charged for 80% of the power in 8 minutes, charged for 10 minutes, and has an endurance of 200-300 kilometers.
Let's first ignore why 80% of the power is why we run 200-300 kilometers, let's say this momentum, properly hang Tesla V3 supercharger! When Tesla was still struggling on the high-nickel route, GAC came to a beautiful corner to overtake, surprised? Surprised?
Calm down! Let's think about it, when was the last big news about graphene batteries? In December last year, Huawei rumored that it would carry a graphene battery on the P40 Pro and charge 70% in 10 minutes. It turned out to be a mistake in hindsight, and the P40 Pro didn't see a trace of graphene batteries when it was later listed.
Around the graphene, the fog is heavy, making people see the flowers in the fog.
The legend of the jianghu is more expensive than gold graphene, what is it?
How is it related to the power battery?
And graphene batteries, what black technology?
Today I will take a look at this magical graphene with you, and the "magical" graphene battery!
Let's start with some theoretical knowledge:
As we all know, carbon has three allotropes, namely diamond, graphite and amorphous carbon.
The carbon used for barbecue contains amorphous carbon, of course, there are impurities in it, and the atomic arrangement of amorphous carbon is somewhat messy, but it is not completely chaotic. Each carbon atom of the diamond is arranged very regularly, and it forms a regular tetrahedron with four other carbon atoms.
The carbon atoms in graphite are a bit special in that they are layered, with each layer of carbon atoms connected to three other carbon atoms to form a hexagonal mesh-like planar structure. The layers are bound by intermolecular forces, so the different layers of graphite are easy to slide. So the key to the house can't fit into the keyhole, you can cut a little pencil lead lubrication. Because the pencil pellet contains graphite, so magical, the pencil contains graphite and does not contain lead, but it is called a pencil.
graphite
Graphene is even more magical, it is a single-layer atomic structure of graphite, if we take a pencil very lightly on the paper to draw a line, maybe there will be a single layer of graphite is peeled off. In 2004, Geim and two of his students at the University of Manchester in the United Kingdom repeatedly peeled off the highly directional pyrolytic graphite with tape to finally obtain a single layer of graphite.
Since the inventor of graphene won the Nobel Prize in 2010, the international research on graphene has begun to explode, and the research papers have increased exponentially, nearly half of which are contributed by Chinese researchers.
Graphene is the world's first discovered two-dimensional material, its thickness of 0.335 nm, about one hundred thousandth of a human hair, TSMC's 5nm in front of it weakly exploded.
Graphene is not just a single layer, it includes single carbon layer graphene, bicarbon layer graphene, multi-carbon layer graphene (3-10 layers). The number of layers can not be too much, too much is graphite.
If you're wearing clothes made of graphene, uh, that's the same as not wearing them.
Heaven will send down a great task to the Scythians, and they will first suffer their hearts and minds, and work their bones and bones...
Graphene has been stripped of only a layer of skin, you say it is not bitter, labor or not? Do you think it should take on big responsibilities?
Obviously, graphene came out with a historical mission.
The special structure of graphene determines its electrical conductivity, thermal conductivity, strength are very good, and the specific surface area is large. Therefore, it has potential applications in computer chips, electronic materials, thermally conductive materials, high-performance composite materials, environmental processing, catalyst carriers and other fields.
Conductivity, thermal conductivity, strength are easy to understand, what does the specific surface area mean? It refers to the total area of a unit mass substance. Substances with a larger specific surface area dissipate heat, and when mixed with other substances, the greater the contact area.
Do you know why there are so many papers on graphene? It is a golden oil in the field of materials, where it encounters difficulties, first take it to try, maybe it will be a miracle.
This is the case in the field of secondary batteries, and the secondary batteries we are talking about are not second-hand batteries, but rechargeable batteries, also known as batteries.
Secondary batteries, from lead-acid to nickel-metal hydride to lithium batteries, have always been a variety of problems. Either the capacity is low, or the life is short, or it is delicate, or it is not safe, or it is slow to charge and discharge. In short, this field is difficult to say, even Musk, who can recover rockets, has made slow progress.
Therefore, the battery meets the graphene, it is a natural success, and it is also the inevitability of history!
Graphene batteries, in fact, so far there is no complete definition.
The research on graphene batteries is also varied, and is roughly divided into laboratory routes and industrial routes.
1. Laboratory route
The laboratory route does not consider industrial transformation, but pursues disruptive innovation, so it is bolder and crazier.
The purpose is to use graphene as the main material, subvert the existing chemical battery, and make a graphene battery that crushes the lithium battery.
An example of an experiment: connecting the two ends of the strip graphene with a wire, and then heating the graphene in a solution of copper chloride, can detect that there is a current on the wire through the instrument. This is because the copper ions in the copper chloride solution become more active during heating, and when the copper ions pass through the graphene, the electrons leave the graphene. After the electrons are free, they will choose a shortest path to move, because the path formed by graphene and the wire is smaller than the resistance of the solution, so the electron selects the path of the wire to travel, generating an electric current.
The energy source of the current in this experiment is heat, which is a research direction of green energy.
In short, the laboratory route is imaginative, but everyone can also see that this kind of research is unlikely to form a product in the short term.
Second, the industrial route
The study of the industrial route is much more practical.
Since it is practical, it is impossible to deviate from the existing battery route.
Lithium batteries naturally become the best target for combining with graphene.
The industrial route includes the following directions:
1. Replace the existing electrode material
First of all, we borrow a classic picture of a lithium battery, about the details of lithium batteries, if you are interested in me to write a separate article in the future, today will not be explained in detail.
Lithium charged after full charge, lithium ions are on the left side of the battery negative electrode (also called anode, everyone pay attention to not write wrong, is the anode), where do they stay? Inside, of course, a material capable of accommodating lithium ions. This material has a specific structure, that is, it can accommodate lithium ions without obvious deformation. Some lithium salts can be used as negative electrodes, and the more common negative electrode material is graphite.
Since graphite can do the negative electrode, the better performance of graphene can of course also do the negative electrode.
But things are not so simple, because the bottleneck of lithium battery capacity is not graphite, but in the right side of the battery cathode (cathode) material, that is, ternary lithium, lithium iron phosphate or whatever.
Although the negative electrode is replaced by graphene, in addition to increasing capacity, it can also improve energy density by reducing weight, and can also speed up charging. However, graphene is too expensive, and it is estimated that all graphene cannot be sold.
Replace the negative electrode material without graphene, then replace the positive electrode material?
This scheme does not need to think, the replacement of the positive electrode is not a lithium battery.
If it cannot be replaced, it can only enhance the activity of the electrode.
2. Enhance the existing electrode material
The characteristics of graphene mentioned above, good conductivity, larger than the surface area, so if added to the electrode can better help the electron movement.
a. Graphene enhances the activity of cathode materials
The methods added include the overlay method and the hybrid method.
The covering method is to form a package on the outside of the cathode material, but this will affect the passage of lithium ions.
Therefore, a more feasible way is the mixing method, such as ultrasonic mixing of LiFePO4 nanoparticles with graphite oxide, and the preparation of LiFePO4/graphene composites with a more complete microstructure, which can greatly improve the magnification performance after the conductivity effect is improved.
b. Graphene enhances the activity of the negative electrode material
The conductivity and structural characteristics of graphene materials are used to assist nanomaterials to improve their lithium-ion transmission rate, thereby improving the magnification performance of lithium-ion batteries and making up for the defects and deficiencies of raw materials.
Graphene, as an addition of anode materials, is more studied than cathode materials, including transition metal oxide/graphene composites and graphene modified silicon-based materials.
3. As a conductive additive
Graphene's excellent conductivity allows it to optimize the conductivity of batteries as a conductive additive.
However, the application of graphene conductive additives in the negative electrode is not economically beneficial, because most of the negative electrode is graphite.
4. Other applications
Graphene can also be used as a material for battery heat dissipation, improving the high temperature performance of the battery by improving the heat dissipation efficiency between the lithium-ion battery and the environment.
The above research directions, as the research of anode material additives, is the most in-depth, but it is this direction that has not yet achieved a breakthrough.
After talking about the research status of graphene batteries for half a day, let's talk about the graphene batteries revealed by GAC this time.
From the information point of view, there are mainly two points:
GAC has its own three-dimensional structural graphene technology.
GAC adds three-dimensional structural graphene as an additive to the positive and negative electrodes of the battery to improve the battery charging performance.
How to say it, lithium battery or that lithium battery, the formula has been slightly changed, and it is an experimental change.
And 3D graphene and we said above graphene is not the same, if it is the above layer of graphene, the price is much higher. There are many kinds of products in the graphene family, including hundreds of 3D graphene researched by GAC.
In fact, there are other companies in the market that are doing graphene batteries, to put it bluntly, they are similar, adding a variety of graphene family products on the basis of lithium batteries.
And really can stabilize mass production, and the performance has indeed been significantly improved, no!
So, this is the lithium battery replaced by a vest!
GAC Group also stressed that whether the technology can eventually achieve mass production still needs to wait for the results of the actual vehicle verification. In addition, the realization of graphene battery fast charging technology also needs to solve problems such as cost and charging facilities.
GAC motor can not be regarded as a big move this time, and excessive interpretation is not good for all parties.