lithium ion batteries electric vehicles Will be most liked in future and suitable for all types of applications. Although all lithium-ion batteries have many aspects in common, there are different types of lithium-ion battery technologies available on the market. Each lithium-ion battery type has its own characteristics, and this means that different types of Li-ion batteries will be used in different areas.
Things to keep in mind when designing a battery pack:
Cell Chemistry:
Choosing the right type of lithium-ion battery for each application is important. Understanding the different types and their characteristics enables selecting the right type for any application.
Some of the most preferred types of lithium-ion batteries in electric vehicles are
“Lithium Iron Phosphate Battery, LFP”
“Lithium Nickel Manganese Cobalt Oxide, NMC”
“Lithium Manganese Oxide”
“Lithium Titanate (LTO)”
Component selection:
The child parts used in the battery pack affect the reliability of the pack.
cells – based on different form factors and good quality cells and chemistry used
bms – Use of a quality PCM or Smart BMS to monitor and ensure the safety of the battery pack
Connection System – Proper selection and size of all electrical components
thermal management:
Thermal management is of particular importance in high power design, particularly for automotive applications in tropical climates. It is important to have air or liquid cooling ducts, pumps or fans and heat exchangers to operate at high temperatures or heaters for operation in low temperature environments as a feature of the battery structure. The design of the cells should be helpful for monitoring the flow of heat inside the pack.
robust design:
Cell Spacing: From empirical studies we know adequate insulation, or an airgap is recommended to protect adjacent cells from overheating and to maintain thermal runaway and thermal diffusion.
Adequate definition or verification of weld quality
Dust and water ingress protection
crush/crash flexible design
A battery pack is a hierarchical and repetitive combination of individual cells. challenges in battery pack assembly process are
Different battery cell types: The assembly process needs to be setup for each type of battery cell type due to the different cell size, shape, form factor and capacity. This investment adds to the cost if the decision is to build packs with different battery cell types.
different pack layout: The pack design changes with the application requirements which in turn changes the number of cells in the pack. Thus, different pack configurations make it difficult to fully automate the assembly process if the goal is to cater to many different markets. Assembly lines need to be flexible to accommodate different battery pack designs and their varying rates and capacities.
Shock and fire hazard: The packs are assembled with the cell at 40-50% state charge. As the pack size increases, the voltage and current capacity of the pack increases. This increases the risk of shock and fire hazard during the assembly, shipment, storage and integration process.
Auxiliary Components:module And there is a need to install Battery Management System in the packs for better operational control. In addition, the pack may require a cooling system component. All such and other ancillary structural, mechanical and electrical components add to the complexity of the assembly process.
The assembly of the battery pack is divided into the following steps
cell sorting: This is the most important step to ensure the safety of the battery pack, it is a process of identifying and grouping cells with similar parameters and characteristics, so they have similar performance during the operation cycle. The common sorting method is based on voltage, capacitance and AC internal impedance (ACIR). Other sorting methods are based on electrochemical impedance spectroscopy and its equivalent model parameters, charge and discharge voltage curves, dynamic parameters, and thermal behavior. Cells with similar operating voltage, capacity and internal resistance are grouped together in a battery pack, to ensure the stability and stability of the entire pack during its life.
Module Assembly: Cells from a group are welded in a series and parallel combination to form a module. Cells can be connected first in parallel then series or first in series then in parallel or mixed series and parallel connections. Tab-to-tab or tab-to-bus bar connections are welded to the cell. Modules are tested as per specifications for quality assurance.
pack assembly: The modules are assembled in series and parallel configurations to achieve
Final pack level voltage and capacity. The pack is housing and sealed to avoid any internal damage. Other ancillary components such as the cooling system and mechanical connections are also made. Finally, the master is installed in the BMS pack.
Final testing and storage: Pack is tested for uniform charging of all cells and other packs
Parameters such as voltage, and impedance. The pack is then stored at
These processes are required to be followed in a defined order so that the quality and performance of the product is maintained.
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