Secret of the Joint Slava battery: How to add new power?

　　Author ：Iflowpower – Portable Power Station Supplier

Recently, Tesla's 100KWH model has passed the EU certification body RDW assessment. This means that the Models / X100D model is coming soon! Its battery life will reach 613KM (based on NEDC standard). According to the European Union, the models sold by the EU member states are not certified by their authorization agencies.

RDW is a Dutch company in Tesla, which will be available in EU sales after its certification. Let's explore, how do this 100kwh do? Elonmusk has said that Tesla's battery life (electricity) is added to 5% of each year. From the iteration of the current battery pack, this goal is basically implemented.

In addition to the 60KWh of the entry-level configuration, 70kWh, 85kWH has been upgraded to 75kWh and 90KWH, respectively. Soon after, 100KWH and 120KWH battery packs will also enter the optional list. At present, 60kwh is still existed as a 乞丐 version to promote Tesla's sales.

True story, 70kwh and 85kwh, how to add 5KWH power. One thing can be sure, that is, during the new process of battery pack, the structure of its battery pack is not changed. The number of BatteryModule has not changed.

Let's take a brief understanding of the internal structure of the underlying Tesla battery pack. There are 14 battery packs inside 60kWh. There are 384 cells in each battery pack, with a total of 5,376 batches; 85KWH consists of 16 battery packs, including 444 cells in each battery pack, a total of 7102 electric batches Core composition.

The 70KWh added later, is actually a 75KWH battery pack, after the software is limited. Excess 5kwh, originally used as a $ 3,000 option to supply to the owner. As long as the OTA software is updated, 70D can become 75D.

So, what is the problem? How is the 75KWH battery pack? About this problem, Tesla official did not make technical explanations. According to the author's judgment, 75KWH is actually an 85KWH battery pack, reducing 2 battery packs. In the 85KWH battery, the capacity of each battery pack is 5.

3kWh, 14 such battery packs are 74.2kWH. This is 70kWh, 75kWh, and 85kWH relationships.

As for 60kwh, this is just a configuration set to reduce the pass threshold. So, how come 90kWh coming? From 85kWh to 90kWh, more than 5KWH. Is it possible to add a battery pack? In the 85KWH battery pack structure, it has no longer overlapping the battery pack.

The only possibility is to replace the new battery. Of course, it is still an 18650-model cell, but the chemical materials are adjusted, and the energy density has been added. In this step, Tesla adds a small amount of silicon to the graphite anode of the battery, which enhances the energy density of the battery.

Silicon is added in the anode, which is already a method that can enhance energy density can be improved. For the alert, the battery pack is constantly overlapping, and the quality of the battery pack is too large. Tesla will only put the focus on the core of the high-energy density.

However, there are so simple to add energy density through silicon to strengthen the energy density through silicon. The basic principle is that after the addition of silicon in the graphite anode, the graphite can accommodate more lithium ions due to the structure of the silicon atom, resulting in strengthening the anode to lithium ions. In a single charge and discharge cycle, the more the aqueous lithium ions, the greater the energy density.

However, after sufficient absorption of lithium ions, its volume will expand 300%, which is more than 7% of the expansion ratio of lithium ions. This repeated volume change can cause the solid electrode to become soft, easy to disintegrate. In this way, the battery life will decrease.

Another layer of factor is that the expansion / telescoping characteristics of the silicone anode due to the charge and discharge are destroyed. This film is formed when the lithium-ion battery is initially circulated, and the anode material has a protective purpose, and the material structure can be collapsed. Based on the above original, the silicon material is used to make an anode, although the energy density can be significantly improved, Also accompanying the secondary use, will eventually cause the battery life shortened.

Therefore, Tesla takes the way to gradually add a small amount of silicon in the graphite anode, looking for a balance point in the energy density and cycle life. As we all know, Tesla's 18650 battery is processed by Panasonic. As both parties work together, Tesla is also developing new cylindrical batteries.

After modeel3 is officially put into production, the new 21700 battery will replace 18650 and become a new battery. 21700 battery is still a ternary lithium-ion battery, cathode material is a lithium nickellate acid (NCA). This cylindrical ternary battery is the power lithium-ion battery treatment for energy density.

Compared to the square battery, although the energy density is high, but the stability is poor, there must be more excellent BMS (battery management system) support. Tesla's earliest Roadster uses Panasonic NCR18650A battery, rated voltage 3.6V, capacity 3.

1ah. The previous 85KWH battery pack is NCR18650B battery, rated voltage 3.6V, capacity 3.

1ah. 90KWH battery models are not known, but should not supply finished products from Panasonic, but Tesla and Panasonic jointly developed, specialized battery cells for Tetra models. At present, in the 18650 battery of Panasonic, the NCR18650G type is the highest capacity, reaching 3.

6ah. If you follow this calculation, the 7102 battery in the 85kWh battery pack is replaced with a G type battery, just 90KWH. Therefore, there is a possibility that in the 90KWH battery pack, the battery is NCR18650G type; and the battery cell is NCR18650B type in the 85KWH battery pack.

In summary, in the case where the number of batches is unchanged (the battery pack structure is unchanged), only the capacity of a single cell is increased to 3.6ah to ensure 90kWh power. To achieve 100KWH, there are two ways: one is to overlap 2 battery packs, according to the capacity of 5.

3kWh per battery pack, it can get 100KWH; second, the battery cells replacing energy density. The author believes that the latter is the best and is the most likely one. Because 90KWH is based on the 85kWh battery pack structure.

This structure is stitched, and the cost of changing its design structure is high at 18650 battery specifications. In fact, there is no space in the battery pack to overlap more battery packs. If the new battery pack is added, the quality of the battery pack will be added, but the battery pack cooling cycle system must be changed.

Therefore, lifting the battery capacity is the most economical approach. Imagine that in the 100kWh battery pack, the capacity of a single cell should be increased to 3.9ah without changing the battery pack structure, and it is possible to achieve 100KWH capacity.

Therefore, the author guess Tesla has developed 3.9ah 18650 battery with Panasonic. This credit can only be attributed to silicon in the anode.

.