The various kinds of lithium power battery black technology, in fact, the principle is the same?

The process of using energy in human society, from 4 billion years ago to the industrial revolution 200 years ago, is the use of photosynthesis; while Watt invented the steam engine, the internal combustion engine of the second industrial revolution, humans began to use fossil energy such as coal and oil. Recently, human beings have paid attention to the comprehensive utilization of energy, requiring efficient collection, storage, and transportation of energy.

Humans collect all the energy, which is first converted into electricity. The storage of electrical energy has become a top priority in the use of energy, which is dominated by electrochemical devices, from capacitors to batteries, to fuel cells, to supercapacitors. Different applications use different electrochemical devices.

Professor Lu Yunfeng said in the "Intellectual Energy International Forum" that the types of batteries are varied, but the purpose is to achieve the same goal. They want to make the power bigger, the capacity density higher, and the lifespan longer. So how do you get the battery done? Going back to nature understands that photosynthesis is the most primitive process of energy conversion on Earth.

Sunlight breaks down water into electrons and protons on chlorophyll, electrons have electron channels, and protons have proton channels. Through internal synthesis, carbon dioxide is turned into a hydrocarbon material. The most important thing in this process is to have independent protons and electron channels.

This is the same for lithium batteries. Lithium-ion batteries are the first lithium iron phosphate to graphite. Graphite for the negative electrode and lithium iron phosphate for the positive electrode. During discharge, the lithium embedded in the graphite loses electrons and turns into lithium ions, which ran out and turned into iron phosphate with lithium iron phosphate.

The relationship between lithium ions and electrons is interdependent. Without electrons, there is no ion. Without ions, there is no electron. The slower speed between the two determines the power of the battery. In addition, the stability of the lithium ion channel and the conductive line affects battery life.

It can be seen from this process that it is important to build a lithium-ion battery into a battery with high energy density, high power, and long life, and to establish an efficient and stable ion electron channel.

The establishment of efficient and independent ion electron channels can work hard from materials. Lithium-ion battery materials generally have poor conductivity, while carbon coating can increase conductivity; lithium ion conductivity is not good enough, the particles can be made small, so that lithium ions do not need to move too long distance, which is why The reason why the lithium power battery electrode material is getting smaller and smaller on the market, in addition, the small particles can make the structure more stable.

At present, the research direction of lithium batteries is mostly the same. Conductive ions are also required for the electrode material. The solution for research is to use graphene, one for carbon tubes, and of course other carbon materials. Then the material is made into nanoparticles, or the nanowires are combined with the carbon tubes, so that the process of conducting the ions is realized, and the structure can be made stable.

Taking nanowires as an example, nanowires and composite structures with carbon tubes are very conductive and are excellent materials for supercapacitors. In order to make the ionization faster, vanadium pentoxide is also used, which is a layered material, which has a lot of space in itself, and we can further increase the layer spacing from 0.35 nm to 0.45 nm. Lithium ions run faster. This composite can be used not only as a material for supercapacitors but also as a material for sodium batteries and sodium capacitors. After all, sodium is cheaper and reserves are much more than lithium.

Nanoparticles are also the same, but more research. In addition to directly mixing nanoparticles with carbon tubes, another method is to assemble small nanoparticles into spherical and carbon tubes. Such a structure enables the battery to have higher magnification and longer life.

It is worth mentioning that nanoparticles are often made lipophilic, that is, natural water repellent. The other is hydrophilic, which requires special treatment. Usually, the carbon tube is easy to adsorb acrylic acid, so that when the nanoparticle is combined with the carbon tube, the carbon tube can be first adsorbed with a little acrylic acid.

In addition, there is a simpler method called spray drying. That is, the nanoparticles, carbon tubes or conductive materials are directly spray-dried to form individual particles. This has the advantage that during the spraying process, the carbon tube will protrude to form a special structure with the material such as iron oxide, so that the outside of the material is not electrically conductive, while the inside has good electrical conductivity. This technical principle is as easy to industrialize as sprayed milk powder.

The battery material not only has positive and negative electrodes, but the electrolyte is also extremely critical. At present, researchers have developed an additive that can realize the negative ions in the electrolyte, and only the positive ions move. As a result, the lithium ion moving speed will increase geometrically, and the battery can be charged and discharged at a high rate to achieve fast charging.

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