What is lithium ion power pack and its composition
Lithium batteries as high voltage battery are favored by 3C digital, power tools and other industries because of their advantages of high energy density, environmental protection, long life and fast charging, and their contribution to the new energy vehicle industry is particularly prominent.
Next, we will help you understand the classification, composition, process flow and production line of the lithium ion power pack.
Basic introduction of lithium ion power pack
New energy vehicle three-electric system
Lithium ion power pack and chassis integration
Classification of lithium ion power pack
1.What is a lithium ion power pack
The general distinction between lithium battery cells, lithium battery modules and lithium battery lithium ion power packs:
Battery cell: the most basic element that constitutes the battery lithium ion power pack and battery lithium ion power pack, generally the voltage that can be provided is between 3v-4v;
Battery lithium ion batteries: a collection of multiple monomers to form a single physical module, providing higher voltage and capacity.
Battery lithium ion power pack: It is generally composed of multiple battery lithium ion power packs. At the same time, a battery management system (bms) is also added, which is the final product provided by the battery factory to the user.
Composition classification of lithium power PACK
As the core component of lithium ion power pack, batteries are currently classified into three main categories according to the shape of the batteries: prismatic shells, cylinders, and soft lithium ion power packs (polymer batteries). The positive and negative electrodes are encapsulated into corresponding casings in different ways.
2.Battery module
By assembling a single cell, the cells are formed into different series and parallel through the bus bar, which can be screwed, resistance welding, ultrasonic welding, ultrasonic aluminum wire welding and laser welding.
Taking into account the production yield, efficiency and internal resistance of the connection point, laser welding is currently the first choice for many battery manufacturers.
3.Lithium ion power pack
Composition of lithium ion power pack
It mainly includes several parts of battery module, mechanism system, electrical system, thermal management system and BMS.
1.Battery module
The battery module is responsible for storing and releasing energy to power the car.
Mechanism system
It is mainly composed of battery lithium ion power pack upper cover, tray, various metal brackets, end plates and bolts, which play the role of support, mechanical shock resistance, mechanical vibration and environmental protection (waterproof and dustproof).
3.Electrical system
It is mainly composed of high voltage jumper or high voltage wiring harness, low voltage wiring harness and relay. The high-voltage wiring harness can be regarded as the “large arteries” of the lithium ion power pack, which continuously transmits the power of the heart of the power battery system to the various required components.
The low-voltage wiring harness can be regarded as the “neural network” of the lithium ion power pack, which transmits detection signals and control signals in real time.
4.Thermal management system
There are four main types of thermal management systems: air cooling, water cooling, liquid cooling, and phase change materials. Taking the water cooling system as an example, the thermal management system is mainly composed of cooling plates, cooling water pipes, heat insulation pads and heat conduction pads.
5.BMS
Battery management systemBattery management system. It is mainly composed of CMU and BMU.
●CMU: Cell monitor Unit, which is responsible for measuring parameters such as voltage, current and temperature of the battery, as well as functions such as balancing. When the CMU measures these data, it transmits the data to the BMU through the battery “neural network” mentioned earlier.
●BMU: Battery management Unit battery management unit.
It is responsible for evaluating the data transmitted by the CMU. If the data is abnormal, it will protect the battery, issue a request to reduce the current, or cut off the charging and discharging path to prevent the battery from exceeding the permitted usage conditions, and also manage the battery power and temperature.
According to the previously designed control strategy, the parameters and states that need to be alerted are judged, and the alert is sent to the vehicle controller, and finally conveyed to the driver. Here are the related top 10 battery management system suppliers.
Process flow
The battery lithium ion power pack is the core energy source of new energy vehicles, providing driving power for the whole vehicle. As the core component of new energy vehicles, its quality directly determines the performance of the whole vehicle. Lithium battery manufacturing equipment is generally divided into three types: front-end equipment, middle-stage equipment, and back-end equipment.
The equipment precision and automation level will directly affect the production efficiency and consistency of products. Although the types of cells and modules are different, the composition and process of lithium ion power pack are generally the same. It is mainly divided into assembly process, air tightness testing process, software writing process, electrical performance testing process, etc.
Introduction of production line
There are many flexible circuits and press-fitting and tightening in the lithium ion power pack assembly process. The difficulty of automation is high and the input-output ratio is not high.
Therefore, the automation degree of the back-end equipment will be lower than that of the front and middle parts, but it is compatible with cylinders, prismatic shells, And three kinds of lithium ion power pack battery lithium ion power packs in soft lithium ion power pack.
Work stations that may require automation:
●The lower shell is automatically online
●Module automatically goes online into the shell
●Module fixed and tightened
●Line and tighten the upper cover
●Automatically apply A/B thermal adhesive (depending on the process)
●Automatic application of sealant (depending on the process)
●Finished product offline
In addition, some will propose that the bronze medal installation and screw tightening, air tightness test, and EOL test also require automatic methods. This is relatively rare, and the stability is difficult to guarantee.
There are two main types of operation of the back-end lithium ion power pack line mass production equipment:
1. AGV + assembly trolley
In the past, it was mainly used in car factories, and now battery factories are slowly promoting this model.
2. Conveyor line + pallet mode
Roller line/roller friction line/multiple chain conveyor line
Summary
As the development of the power battery industry gradually matures, the lithium battery pack modular technology will become more and more mature. The development of lithium ion power pack technology involves multi-disciplinary and multi-field knowledge and requires interdisciplinary technology integration.
All in all, car companies, including top 10 power battery companies, want to produce power battery pack products on a large scale that fully meet the requirements of new energy vehicles in terms of lifespan, stability, reliability, and safety, and require a lot of engineering practice and test verification. And the process of continuous optimization and upgrading of products.
