How to increase the energy density of lithium battery?

2022/04/08

  Author :Iflowpower – Portable Power Station Supplier

What is the energy density? EnergyDensity refers to the size of energy storage energy in a certain space or mass material in units. The energy density of the battery is also the electric energy released by the battery average unit volume or mass. The energy density of the battery is generally divided into two dimensions of energy density and volume energy density.

Battery weight energy density = battery capacity ¡Á discharge platform / weight, basic unit is WH / kg (watt / kg) battery volume energy density = battery capacity ¡Á discharge platform / volume, basic unit is WH / L (watt / liter) The larger the energy density of the battery, the more power stored in unit volume, or the weight stored in weight. What is a monomer energy density? The energy density of the battery often points to two different concepts, one is the energy density of the monomer battery, one is the energy density of the battery system. The battery is a minimum unit of a battery system.

M cells form a module, n-modules form a battery pack, which is the basic structure of the vehicle power battery. Monomer battery energy density, as the name implies is the energy density of a single cell level. According to the "China Manufacturing 2025" clarified the development plan of the power battery: 2020, the battery energy density reached 300Wh / kg; in 2025, the battery energy density reached 400Wh / kg; 2030, the battery energy density reached 500Wh / kg.

Here, it is the energy density of a single cell level. What is the system energy density? The system energy density refers to the weight or volume of the entire battery system after the completion of the monomer combination. Because the battery system includes battery management system, thermal management system, high and low pressure circuit, etc.

, the energy density of the battery system is lower than the single energy density of the battery system. System energy density = battery system power / battery system weight OR battery system size What is limited to the energy density of lithium batteries? The chemical system behind the battery is main reason to can't escape. In general, four parts of the lithium battery are very critical: positive, negative electrode, electrolyte, diaphragm.

The positive and negative is where the chemical reaction occurs, which is equivalent to the second pulse, and the important position can be seen. We all know that the energy density of battery pack systems with tricolithic lithium is higher than the battery pack system based on lithium iron phosphate. Why is this? The existing lithium-ion battery negative electrode material is mainly graphite, the theoretical gram of graphite 372mAh / g.

Positive electrode material lithium iron phosphate theoretical gram is only 160mAh / g, while the three-dimensional material nickel-cobalt manganese (NCM) is about 200mAh / g. According to the theory of wooden barrel, the high and low water level determines the shortest in the wooden barrel, the lower limit of the energy density of the lithium-ion battery depends on the positive material material. The voltage platform of lithium iron phosphate is 3.

2V. This indicator of the ternary is 3.7V, two-phase comparison, and the energy density is high.

: 16% difference. Of course, in addition to the chemical system, the production process level such as compact density, the thickness of the foil, can also affect the energy density. In general, the larger the compact density, the higher the capacity of the battery in a limited space, so the compaction density of the main material is also seen one of the reference indicators of battery energy density.

In the fourth episode of "Great Guoda II", Ningde Times used 6 micron copper foil, using advanced process levels, improved energy density. If you can read it all the time, I have been reading here. Congratulations, your understanding of the battery has been on a level.

How to improve energy density? The adoption of the new material system, the improvement of the lithium battery structure, the improvement of manufacturing capacity is the three stage of research and development engineers "long-sleeved good dance". Below, we will explain two dimensions from monomers and systems. - Single energy density, mainly relying on the breakthrough of the chemical system 1.

Increase the battery size battery manufacturers can achieve the effect of power expansion by increasing the original battery size. Our most familiar example is that it is more than: take the lead in using Panasonic 18650 batteries to Tutla will replace new 21700 batteries. But the battery is "gain" or "long" just the standard, not to.

The bottom of the suction is the key technique to improve energy density from the positive and negative material and electrolytic liquid components constituting the battery unit. 2. Previously, the chemical system change mentioned that the energy density of the battery is subject to the positive and negative of the battery.

Since the energy density of the current negative material is much greater than the positive electrode, it is necessary to increase the positive material material in increasing the energy density. The high-nickel positive electrode three-membered material is connected to the nickel-cobalt-oxidate large family, and we can change the performance of the battery by changing the ratio of nickel, cobalt, manganese. The ratio capacity of the silicone carbon negative electrode silicon base material can reach 4200 mAh / g, which is much higher than the 372mAh / g of the graphite negative poor comparative capacity, so the strong substitute for the negative electrode of the graphite.

At present, the way the battery energy density is used to improve the energy density of the industry with silicon carbon composite materials. Tesla 3 uses silicon carbon negative electrode. In the future, if you want a hundred feet to further - break through the gate of the monomer cell 350WH / kg, the industry's peers may need to focus on the lithium metal negative pole battery system, but this also means the entire battery production process.

Create and refine. It can be seen in several typical three-yuan materials, and nickel is getting higher and higher, and the proportion of cobalt is getting lower. The higher the content of nickel, it means that the higher the specific capacity of the battery.

In addition, due to the scarce of cobalt resources, improve nickel ratio, reduce cobalt usage. 3, system energy density: the group test of the grouping efficiency battery pack of the battery pack is the capacity of the battery "siege" to the monomer battery and the module, and needs to be premised on safety. Maximize every inch space.

The "slimming" of the battery pack mainly has the following ways. Optimizing the arrangement from the dimensions of the exterior, optimizing the arrangement within the system, so that the internal parts of the battery pack is more compact and efficient. Topology Optimization We achieve weight loss design by simulation calculation in ensuring the rigidity and structural reliability.

Through this technology, the topology optimization and morphological optimization can eventually help realize the battery case light quantification. Wositives We can choose low-density materials, such as battery packs have gradually changed from conventional sheet metal cover to composite cover, which can wear 35%. In response to the box under the battery pack, it has gradually changed from the traditional sheet metal solution to an aluminum profile, and the weight is about 40%, and the lightweight effect is obvious.

The whole vehicle integrated design of the vehicle integrated design and the vehicle structure design of the whole vehicle structure, sharing, shared structural parts, such as anti-collision design, realizing the ultimate lightweight battery is a very all-round product, you have to enhance some one Aspects of performance may sacrifice other performance, this is the understanding of battery design research and development. Power batteries belong to car dedicated, so energy density is not a unique scale measuring battery quality.

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