One article to see clearly: Kirin battery vs. Tesla 4680 battery, which one is better?

Shortly after Tesla announced that it would mass-produce 4680 batteries for installation in vehicles, CATL launched its own third-generation CTP technology - Kirin battery.

According to CATL, the volume utilization rate of Kirin batteries exceeds 72%, and the energy density can reach 255Wh/kg, which can enable the vehicle to have a range of over 1,000 kilometers.

In addition, this Kirin battery also uses the world's first large-area cooling technology for battery cells, which can support 5-minute fast hot start and 10-minute fast charging.

It is reported that the battery is planned to be mass-produced and launched in 2023.

After the release of Kirin batteries, Ideal Auto and Nezha Auto successively forwarded the news of the release of Kirin batteries, and CATL’s official Weibo account also responded to the news of the two companies. Ideal and Nezha also became the first new energy companies confirmed to be equipped with Kirin batteries.

Regarding this battery, according to the official description of CATL: Under the same electrochemical system and battery pack size, the material used is the ternary high-nickel version of the Kirin battery, which can have an energy density 13% higher than the Tesla 4680 of the same volume, and its performance far exceeds that of the Tesla 4680.

Is the Kirin battery really better than the Tesla 4680 battery? Let's take a closer look at the differences and gaps between the two.

External upgrade vs internal upgrade

In fact, Kirin battery and 4680 battery are two different technical concepts. Kirin battery is the iteration of battery system technology, while Tesla 4680 is the iteration of battery cell technology.

1. Kirin Battery

Let’s first look at the Kirin battery. It does not change the internal structure of the battery cell in essence, but changes the structure of the battery system. Its main innovations are as follows:

1. Adopt the design of inverted battery cell

Unlike the standing CATL VDA and 590 modules and the lying SAIC Rubik's Cube battery, the CTP3.0 True Kirin battery is an inverted battery, that is, the battery cell is inverted. This design can make the battery pack more space-efficient.

From the perspective of arrangement, when the Kirin battery cells are inverted, the uncontrolled exhaust and bottom ball hitting space can be shared, leaving 6% more space for the cells, thus bringing higher space utilization. Currently, the space utilization rate of Kirin batteries is as high as 72%, 17% higher than the first generation CTP.

2. Integrated into a multifunctional elastic sandwich

CATL's pioneering horizontal and vertical beams, water-cooled plates and thermal insulation pads, which were originally designed independently, are integrated into a multifunctional elastic interlayer, combining support, cooling, thermal insulation and buffering functions into one, effectively improving space utilization.

In addition, a micron-bridge connection device is built inside the multifunctional elastic interlayer, which can flexibly cooperate with the breathing of the battery cell to freely expand and contract, thereby improving the reliability of the battery cell throughout its life cycle.

In addition, the battery cells and multifunctional elastic interlayer form an integrated energy unit, which builds a stable force-bearing structure perpendicular to the driving direction, thereby improving the battery structural strength and impact resistance.

3. Reconstruct the water cooling system

In terms of cooling, Kirin Battery has made a brand-new layout design for the cooling system.

First of all, CATL started from the essence of heat exchange and reconstructed the water cooling system, placing it between the large surfaces of the battery cells, which greatly improved the heat exchange efficiency of the battery cells and expanded the heat exchange area four times.

Secondly, CATL has shortened the battery cell temperature control time to half of the original time, more efficiently maintaining the safe and suitable working temperature of the battery cell, so as to adapt to higher current and higher voltage fast charging. It is reported that the Kirin battery can currently support a 5-minute fast hot start and a 10-minute fast charge to 80%.

In extreme cases, the battery cells can be cooled rapidly, effectively blocking abnormal heat conduction between battery cells, effectively avoiding irreversible damage caused by abnormal operating temperature of the battery, and effectively improving the life and safety of the battery cells.

To sum it up in one sentence, Kirin batteries have achieved comprehensive improvements in battery life, fast charging, safety, lifespan, efficiency, and low-temperature performance.

2. Tesla 4680 battery

Anyone who knows a little about Tesla knows that Tesla's battery naming is always simple and crude. The 4680 battery, as the name suggests, is a cylindrical battery with a single cell diameter of 46mm and a height of 80mm.

Compared with the past "1865" and the current "2170", judging from the naming, the 4680 seems to have just a larger battery, from the previous "No. 5 battery" to "No. 2 battery".

Of course, it is not that simple. In addition to being larger, the 4680 battery cell also has many innovations and improvements in structure.

1. Adopt "no-ear" design

As the volume of the battery cell increases, the battery impedance also increases. Tesla's solution to this problem is to adopt an innovative "no-electrode ear" design.

The tabs are metal conductors that are drawn from the positive and negative current collectors. The current can only be connected to the outside of the battery through the tabs. However, tabs that are too thin and long are not conducive to current conduction. If the current is too large, heat will occur, energy loss will increase, and safety performance will be affected.

Tesla's 4680 battery has removed the original tabs and chose to leave the positive/negative electrode materials blank at the end of the current collector. In simple terms, it is not that there are no tabs, but that the entire end surface has become a tab. This design greatly reduces the impedance of the battery and solves the heating problem of cylindrical batteries.

2. Use dry battery electrode technology

Tesla's 4680 battery uses a dry battery electrode process that does not use solvents. Instead, a small amount (about 5-8%) of fine powdered PTFE binder is mixed with positive/negative electrode powders, and a thin electrode material strip is formed through an extruder. The electrode material strip is then laminated to a metal foil collector to form a finished electrode. This process will increase the energy density of the battery and reduce production energy consumption by 10 times.

3. Anode is made of silicon material

Tesla will start with silicon materials for anode materials. Silicon can store ten times more electricity than graphite, but it has been difficult to replace graphite because its volume changes by up to 400% during charging and discharging and it is easy to break.

Tesla plans to fundamentally change the ductility of the silicon surface to make it less prone to breakage. This technology can increase the battery life by 20%. Tesla named the new material "Tesla Silicon", which costs $1.2/KWh, only one-tenth of the existing structured silicon process.

4. Improve the cathode production process

In terms of cathode materials, Tesla has reduced the investment and construction costs of the battery cathode production line by 66% and the production costs by 76% by improving the cathode production process and reducing water use and wastewater generation. At the same time, Tesla has launched a battery recycling service, and all new batteries in the future will be produced from recycled old batteries.

Combined with these improvements, Tesla will increase battery life by 54%, reduce cost per kilowatt-hour by 56%, and reduce investment and production costs by 69%. In addition to improving energy density, production costs will be greatly reduced.

Finally, let me summarize the advantages of the 4680 battery in one sentence: it can achieve a balance between performance and cost.

In summary, although Kirin batteries and 4680 batteries have iterative upgrades in battery technology, they are different in their technical routes.

Kirin Battery improves battery performance by upgrading the battery pack structure without changing the battery cell materials, such as changing the placement of the battery cells and integrating them into a multifunctional elastic interlayer.

Tesla's 4680 battery becomes stronger through "internal upgrades" of the battery cell, such as increasing the cell size, changing the anode material, etc.

Of course, whether it is an external upgrade or an internal upgrade, the ultimate goal is still to achieve better battery performance.

So, what is the performance comparison between Kirin battery and Tesla 4680 battery?

Kirin battery performance far exceeds Tesla 4680?

According to the data provided by CATL, the cylindrical 4680 battery is still slightly inferior to the Kirin battery in terms of energy density, fast charging performance, integration and thermal conductivity. Let's take a look at them one by one.

1. Energy density

According to the data, the energy density of the 4680 single cell is about 300Wh/kg, and the energy density of the battery pack is 217Wh/kg. In comparison, the energy density of the Kirin battery pack can reach 255Wh/kg. In other words, under the same cell chemistry system and the same battery pack size, the power of the Kirin battery pack is 13% higher than that of the 4680 battery.

2. Volume utilization

In addition, the volume utilization rate of Kirin Battery's battery pack has exceeded 72%, 9% higher than the 63% of the 4680 battery, breaking the industry record and becoming the world's most highly integrated battery.

Kirin batteries have higher space utilization. In addition to structural optimization such as integrating a multifunctional elastic interlayer and inverted battery cells, Tesla's batteries can only be used about 60% because of their inherent cylindrical shape and inherent bugs.