On the necessity of power cell process innovation

Power batteries are power sources for tools, mostly batteries that power electric cars, electric trains, electric bicycles, and golf carts. Power battery as the main power battery is widely used in industry, life and other aspects. Recently, with the production and sale of new energy vehicles, China has become the world's largest market. For a while, the development of the upstream and downstream industrial chain of power batteries has received wide media attention.

Power batteries are the core components of new energy vehicles, which directly determine the performance of the vehicle. The production process can be divided into front-end, mid-end and back-end equipment. The accuracy and automation level of the equipment will directly affect the efficiency and consistency of the battery. In 2020, the total demand for power lithium batteries will reach 37 GWh, which is more than ten times that of 2014. The expansion of power batteries will directly drive the demand for equipment. As a mid-stream equipment linking upstream raw materials and downstream products, laser welding technology began to enter people's horizons, but the mystery of its process application has still been shrouded in a veil of mystery. Benefiting from the laser industry, I feel the pulse point of the development of the industry six points, take the opportunity to remove the veil, secret laser welding in the power battery industry application.

Acupoint 1: Full fusion

For power battery manufacturers, laser welding is a fusion manufacturing process in which the raw materials such as positive and negative electrode materials, diaphragm and electrolyte are zeroed, and it is a key process in the entire power battery production process. Welding all raw materials into battery cores and PACK modules can be directly used in traditional consumer electronics, electronic tools, electric bicycles, energy storage power stations and new energy vehicles.

On the other hand, the position of laser welding in power batteries can also be reflected in the cost value of welding equipment. Compared with the battery raw materials, the raw materials account for a continuous proportion of the cost and are purchased in tons; Laser welding equipment is basically in place once. The value of welding equipment of different processes or types ranges from hundreds of thousands to millions of yuan, accounting for 5-15 % of battery factory inputs, and 10-40 % of battery pack plants.

Acupoint 2: All Comparison

Battery manufacturing involves a wide range of welding techniques, such as ultrasonic welding, resistance welding and laser welding. The proper selection of welding methods and processes will directly affect the production cost, the reliability of the quality and the safety of the use of the battery. Laser welding is a very important process for battery production. It has a great influence on the consistency, stability and safety of batteries. There are many laser welding sites for power batteries, and the process is difficult. The welding process is required to be higher. The high efficiency and precision laser welding can greatly improve the safety, reliability and service life of automotive power cells, and will provide important guarantees for the development of automotive power technology in the future.

It is found that the advantages of laser welding lies in the small loss of welding material, the small deformation of welded workpieces, the stable and easy operation of equipment, and the high degree of welding quality and automation. Its technological advantages are unmatched by other welding methods.

Acupoint 3: Full Process

The core of the power cell can be divided into Square, cylindrical, soft package, 18650 and other different types according to its appearance. Among all types of batteries, the most comprehensive application of the laser welding process is cylindrical battery welding. Take the cylindrical power battery process as an example. The application of laser welding procedures is shown in the following figure:

After going through the above laser welding process, we continue to assemble multiple units of single cores one step at a time to form PACK batteries for electric bicycles and electric vehicles. For example, Tesla, the international leader, used more than 7,000 Panasonic NCR186503100mah cells. Synthesis of PACK batteries, In order to meet the high endurance ability.

Point 4: More efficient

Although the laser equipment used in the market for power batteries is "beautiful and charming gradually" in appearance, it eventually achieves the same effect. According to the complexity of the process and the space occupied by the equipment, laser welding equipment can basically be divided into three types: medium test equipment, fully automatic workstation and fully automatic pipeline.

The test equipment is basically a stand-alone semi-automatic console and is used in the testing and small batch production of initial test products.

Fully automatic workstations, mostly double-sword combined modes, laser hosts plus semi-closed or fully closed worktables, each worktable is generally equipped with multi-position fixture kits, suitable for power cell laser welding and battery PACK welding The single process section automatic system.

The fully automatic production line, an upgraded version of the fully automatic workstation, connects multiple workstations to form a complete intelligent automatic production line for core welding or battery PACK welding.

Point 5: Safer

In recent years, with the rapid development of electric vehicles, how to solve the safety problem of electric vehicles is the key point and difficulty that must be broken through in the benign development of the new energy vehicle industry. Since people have a process of recognizing new things, it is inevitable that they will have doubts and distrust at the beginning. Therefore, any safety accident related to electric vehicles will lead to further deepening public doubts about the safety of electric vehicles and hinder the development and popularization of electric vehicles.

The safety of power cells is widely debated. The batteries themselves should not be bulging, leaking, breaking, burning, smoking, or exploding. Once the heat of the core is out of control, the electrolyte leakage, fire and combustion may occur. The battery explosion relief valve used in lithium battery can effectively prevent the battery from exploding when the heat is out of control, thus guaranteeing the battery safety.

Point 6: Look at the future

In recent years, many domestic and foreign power battery manufacturers have adopted different welding methods for different processes and different welded parts in more complex production processes, and as the new energy automotive industry has developed in depth, It is necessary to adopt laser welding technology on a large scale because of the higher requirements for the assembly and welding precision and quality of matching batteries.

In the future, foreign companies represented by Samsung and LG will be fierce in the afterlife to provide products with high energy density, exquisite craftsmanship and cost-effective prices, which will break the pattern of the domestic power battery market. Domestic power battery manufacturers can only participate in domestic and international competition by upgrading the overall manufacturing process level.

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