What is the method of lifting energy densities in power lithium ion batteries?

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What is battery energy density energy density (EnergyDensity) refers to the size of storage energy in a certain space or mass material. The energy density of the battery is also the electric energy released by battery uniform unit volume or quality. Battery energy density = battery capacity Times; discharge platform / battery thickness / battery width / battery length, basic unit is WH / kg (watt / kg).

The larger the energy density of the battery, the more power stored in unit volume. Cylindrical lithium ion battery configuration diagram related to battery energy density, now we understand that it is a current battery industry, even the most distinct break of the electric car industry, but breaks it, it is really difficult. Ah! △ Typical battery design of non-active substances (except leads, etc.

) It is reported that the energy density of the battery is basically determined by the positive and negative poles of the battery, but is only the positive and negative active material does not guarantee that the battery can be powered. There are many non-active substances, such as conductive adjuvants, binders, isolation membranes, yin and inferior foils, aluminum-plastic film shells or steel aluminum aluminum casings, etc. Most of us always intentionally ignore the content of this part of the substance, and the energy density derived from the facts is large, misleading the people of melon.

In fact, this part is considerably, it takes more than ten years of technical progress. The increase in battery energy density is achieved by the improvement of active substances. △ Energy density change and predictive dynamic lithium-ion battery boost energy density The power lithium ion battery replaces the fuel tank in a certain sense, and the increase capacity can achieve longer life, but the structural design of modern cars has long been Fixed unchanged, even if pure EV is developing, the layout space reserved for the power lithium ion battery is only a fixed position between the front and rear axles.

Under the premise that the layout space is not changed, the overall capacity of the battery is the basis for processing battery life. Since the beginning of 13 years, the domestic pure electric car has been upgraded from 150 kilometers to 400 kilometers, behind the back of the battery life. Power lithium-ion batteries tend to get a larger battery capacity with lighter quality, as the core upgrade is battery energy density.

In essence, the lithium-ion battery refers to a battery assembly that is a positive material with an ion embedded compound. Whether it is a three-dimensional lithium, or a lithium iron phosphate ion battery. The overall charge and discharge process is basically the same, and the performance orientation of different material pursuit is different.

The lithium ion battery is tightly combined by the positive electrode + electrolyte + negative electrode, and the positive electrode material is multifaceted with a compound containing metal lithium, and the negative electrode is mostly using graphite or carbon material. The organic solvent between the two is an electrolyte. When charging, a lithium ion is analyzed by the electrolyte, and the electrolyte enters the battery negative, and embedded in a negative material.

When discharged, the lithium ions embedded in the negative material reflows the positive electrode through the electrolyte, and the more the lithium ions returned to the positive electrode, the higher the battery capacity. The three major paths of the power lithium-ion battery increase energy density. One, lift the lightweight level indirectly improve the power lithium-ion battery energy density in the new energy automobile processing company multi-use steel material to make electric vehicle power lithium-ion battery tray, now many companies are Aluminum alloy material.

The density of the aluminum alloy is 2.7g / cm3, and the aluminum alloy material is very excellent in terms of compression or welding. The magnesium alloy is 1.

8 g / cm3, carbon fiber is 1.5g / cm3, these materials are used to process battery trays, which will greatly improve the lightweight level of new energy vehicles. Prince Dong believes that lightweight technology is still growing, and there will be more lightweight materials in the future.

He said that it should not only study the lightweight of the battery tray, not only the material of the material is lightweight, so that the material of the material can be considered to maximize the energy density of the power lithium-ion battery. Lightweight to reduce the weight of the parts, but can not reduce the strength of the accessories, so the robustness of the material should be considered. In addition, using lighter materials will face the problem of cost increase.

Therefore, in the case where the power lithium-ion battery cost is not largely decreased, the priority of the vehicle is lightweight is to develop a more reliable and economical lightweight material. In 2016, Volvo said that if all current electric car batteries are replaced into new lightweight materials, it can reduce the vehicle over 15%, and the material cost is lower and more environmentally friendly. Second, tangled iron lithium or three yuan is not as good as layout silicon carbon negative electrode as two major mainstream technology routes, nearby, the energy density of ferrite and ternary materials have improved.

Due to the higher energy density of ternary, the subsidy policy is more inclined to high-energy density products, so major battery companies use the three-yuan battery as the main force of the next generation of the company. However, the general manager of BYD Co., Ltd.

believes that although the three-yuan and iron lithium differ in the variable in monomer energy density, the energy density of the system after group is different, and there is also difficulty in cost and battery storage. No big difference. Therefore, Shen Yizu proposes that the company can consider the use of silicon materials (such as a silicon oxide negative electrode material, etc.

) in mass production products in mass production products, thereby using silicon materials (such as silicon oxide negative electrode materials, etc.) in mass production products. Overall energy density.

Third, Changing the battery size Rapid system Energy density change battery size is still an effective way to improve battery energy density. Although Tesra chose 18650 technology route successfully attracted the follow-up of many domestic power lithium-ion battery companies, but due to small capacity of the 18650 battery, it is generally 2-4ah, too much in series, and the probability of monomer failure is more Large, leading to its use of mainstream new energy passenger cars and bus categories. In 2017, Tesla, which took the 18650 battery, turned its attention to 21700 batteries and has achieved mass production.

According to Tesla CEO Mask, when using the Model3 car of the 21700 battery, it will re-audit whether the 21700 battery manufacturing modls and modelx model vehicles will be used. Once the audit passes, 21700 battery is likely to replace 18650 batteries on Tesla car. It is understood that Tesla uses a 21700 battery, due to the equivalent energy, the number of batteries is reduced by about 1/3, which will bring the reduction in the number of metal connectors in the entire PACK, thereby further reducing the weight of the battery pack.

The energy density of the car will be partially improved. And this way is also a reference for domestic 18650 battery companies to improve energy density and reducing this. It is understood that the domestic 18650 battery company is basically recognized by Tesla's way and is also related layout.