Keyword search: battery plant , lithium battery factory , power bank works , lifepo4 battery mill , lithium forklift battery manufacturer

keyword：Forklift Lithium Battery | Lithium iron phosphate battery | NCM Lithium Battery

Tesla will use 20700 instead of 18650 as the power lithium-ion battery. From 18650 to 20700, the size will change, while Tesla will continue to use cylindrical batteries.

Why does Tesla have a particular fondness for cylindrical batteries? What are the advantages of cylindrical batteries that Tesla, as a technical man, cannot forget? The editor will analyze it based on the current lover 18650.

Regarding the technical route of using 18650 battery cells as new energy electric vehicle batteries, everyone may first turn their attention to Tesla. Tesla tested many types of batteries during battery development, but ultimately focused on the 18650 battery. What are the advantages and disadvantages of the 18650 battery cells? Let's analyze the true face of the 18650.

First, give a brief understanding of the 18650 cylindrical lithium-ion battery cell

The 18650 we often refer to in daily life actually refers to the appearance specifications of the battery, which is a standard battery model set by Japanese SONY company in order to save costs. Among them, 18 represents a diameter of 18mm, 65 represents a length of 65mm, and 0 represents a cylindrical battery. 18650 batteries originally referred to nickel hydrogen batteries and lithium-ion batteries, but since nickel hydrogen batteries are now less commonly used, they now refer more to lithium-ion batteries. The nominal voltage of a single 18650 lithium-ion battery is generally 3.6V or 3.7V; The minimum discharge termination voltage is generally 2.5-2.75V. The common capacity is 1200~3300mAh.

Regarding consistency

18650 battery is the earliest, most mature, and most stable lithium-ion battery, widely used in electronic products. Over the years, Japanese manufacturers have accumulated a lot of relevant experience in the production process of 18650 batteries, resulting in a very high level of consistency and safety in the production of 18650 batteries.

In contrast, stacked lithium-ion batteries are far from mature. Common types include square batteries, soft pack batteries, and even inconsistent sizes, sizes, and ear positions. The production processes possessed by battery manufacturers cannot meet the conditions, and most of them are mainly controlled by humans. The consistency of the battery cannot reach the level of 18650 batteries. If the consistency of the batteries cannot meet the requirements, the management of battery packs formed by a large number of batteries in series or parallel will not allow each battery to perform better, and 18650 cells can solve this problem.

Panasonic 18650 cylindrical battery used by Tesla

In summary, the 18650 battery has a small unit capacity and requires a large number of units (Model S has 7104 units), but the consistency is good; The capacity of stacked batteries can be larger (20Ah to 60Ah), and the number of monomers can be reduced, but the consistency is poor. In contrast, it is currently difficult to invest a significant amount of manpower and resources with battery suppliers to improve the production process of stacked batteries. Therefore, when developing Roadster and ModelS, Tesla's only choice was to purchase batteries from the market and develop their own battery systems. Compared to developing a battery system with good consistency in managing over 6000 units and developing a battery system with poor consistency in managing over 200 units, the technical difficulty of the former should be lower. Even if the number of individual batteries increases, if the performance of these batteries is reliable, it is still easier to manage.

Compared to another highly successful pure electric vehicle, Nissan's LEAF, which uses stacked lithium-ion batteries. This is because Nissan has cooperated with NEC for many years and has accumulated profound experience in battery technology. It should have considerable skills in quality control. LEAF's batteries come from a joint venture between AESC, Nissan, and NEC.

It is very interesting to compare the vertical and horizontal integration between automobile manufacturers in different regions of the United States, Japan, and China when developing electric vehicles and battery manufacturers.

Regarding heat dissipation capacity

The thickness of the stacked battery is thin, the surface is large, and the heat absorption and heat dissipation capabilities are good. Therefore, Nissan's LEAF boldly adopts a passive heat management system (which is actually not managed!), which is carried away by the natural convection of air.

From left to right, LEAF moves from a single battery to a battery module composed of four single batteries in two parallel and two in series, and then to a battery pack composed of 48 battery modules in series, as shown in the following figure:

NEC stacked batteries used in Nissan LEAF

It can be seen that there are no thermal management systems such as fans or coolant pipes on the battery pack. Perhaps this is where there are no tricks to win.

On the other hand, looking at Tesla, the size of the 18650 battery is relatively small, and the temperature difference inside the individual battery during normal charging and discharging is not too large. However, the temperature of over 6000 individual batteries should also be maintained within the range of 5C, which is a very difficult task. But Tesla did it. How did it happen? What are the advantages of Tesla's Battery Management System (BMS) compared to other electric vehicles? Liquid cooling system in Tesla battery modules

As shown in the above figure, these pipes are the flow channels for the coolant, which are evenly distributed in the middle of the battery module, allowing each cell to come into good contact with the water pipe. This way, the heat carried away by each cell during cooling is almost the same, and the temperature difference can be effectively controlled within a small range.

In summary, Tesla's thermal management system has significantly increased its complexity due to the use of a small capacity 18650 battery. That is to say, if considering the heat dissipation capacity, using a small capacity 18650 battery is not the optimal choice.

Regarding energy density

When it comes to energy density, it is necessary to distinguish between the energy density of individual batteries and the energy density of battery packs.

In terms of energy density of individual batteries, 18650 batteries are higher than stacked lithium-ion batteries. The energy density of the 33Ah lithium-ion battery used in the Nissan LEAF I found here is 157Wh/kg, while the energy density of the stacked battery used in the GMVolt is approximately 150Wh/kg; The energy density of the 18650 battery used in the Roadster is approximately 211Wh/kg. However, the management system of the 18650 battery is more complex, and the additional weight added will result in the energy density of the battery pack being much lower than that of the individual cells. The Roadster battery pack weighs 450kg with an energy density of 118Wh/kg, while the LEAF battery pack weighs 225kg with an energy density of 107Wh/kg. At the battery pack level, the energy density of the two is already on par.

Regarding security

The various advantages of stacked lithium-ion batteries were mentioned earlier, but they also have some drawbacks. Due to the fact that stacked lithium-ion batteries are generally packaged with aluminum plastic film, which has a thin thickness and poor mechanical strength, the aluminum plastic film is prone to damage and safety accidents in extreme situations such as car collisions. This also explains why Nissan needs to add an aluminum shell outside the battery module composed of four monomers.

18650 batteries are generally made of steel shells for better safety; And as mentioned earlier, with the continuous improvement of the production process level of 18650 batteries, the safety is also constantly improving.

Tesla has also put a lot of effort into dealing with potential safety accidents that may occur with these 18650 batteries. If a single battery experiences abnormal conditions such as high temperature, depending on the severity of the abnormal situation, the battery or its module will be powered off to prevent the spread of the accident. Due to the small capacity of the monomer, as long as there is no spread, the severity of the accident will be relatively low.

Related costs

18650 lithium-ion batteries have the characteristics of large capacity, long lifespan, high safety performance, and are highly favored by consumers due to their small size, light weight, and convenient use. With the continuous deepening of research on 18650 battery technology, the consistency and safety of batteries have reached a very high level. As the earliest lithium-ion battery, the 18650 battery is also the most mature and stable battery combination in the world, and still occupies a leading position to this day. China produces approximately several billion units of 18650 batteries annually, which far exceeds that of batteries made of other materials.

Tesla, on the other hand, uses 18650 batteries and can utilize previous production lines from Japanese manufacturers such as Panasonic for production. Under the increasingly fierce competition of 18650 batteries used in consumer electronics, Panasonic and other manufacturers cooperated with Tesla to upgrade products and use the original production line to produce power lithium batteries. Industrial production has a scale effect, and when the scale of the produced product reaches an order of magnitude, the cost will be greatly reduced. A new energy vehicle requires thousands of 18650 batteries, so the procurement cost of individual units is controllable.

It can be said that using cylindrical batteries such as 18650 and 20700 as the power source of new energy electric vehicles is the optimal choice at this stage. However, with the maturity of battery technology and processes, there will also be more new types of batteries applied in new energy electric vehicles in the future.

Lithium ForkLift Batteries ,Ensure Quality

Our lithium battery production line has a complete and scientific quality management system

Ensure the product quality of lithium batteries

Years of experience in producing lithium forklift batteries

Focus on the production of lithium batteries

WE PROMISE TO MAKE EVERY LITHIUM BATTERY WELL

We have a comprehensive explanation of lithium batteries

QUALIFICATION CERTIFICATE

THE QUALITY OF COMPLIANCE PROVIDES GUARANTEE FOR CUSTOMERS

MULTIPLE QUALIFICATION CERTIFICATES TO ENSURE STABLE PRODUCT QUALITY

Providing customers with professional and assured products is the guarantee of our continuous progress.

Applicable brands of our products