Lithium-ion Battery Winding Process Guide

Jun 20 , 2024

The winding process of lithium-ion batteries is to roll the positive electrode sheet, negative electrode sheet and separator together through the winding needle mechanism of the winding machine. The adjacent positive and negative electrode sheets are isolated by the separator to prevent short circuit. After winding, the jelly roll is fixed with a termination tape to prevent it from spreading, and then it flows to the next process. The most important thing in this process is to ensure that there is no physical contact short circuit between the positive and negative electrodes, and that the negative electrode sheet can completely cover the positive electrode sheet in both horizontal and vertical directions.

A large amount of experimental data shows that the quality of jelly roll has a significant impact on the electrochemical performance and safety performance of the final finished battery. Based on this, we have sorted out some important focuses and precautions in the winding process of lithium-ion batteries and formed the "Lithium-ion Battery Winding Process Guide". We hope to avoid incorrect operations in the winding process as much as possible, so as to manufacture lithium-ion batteries that meet quality requirements.

1. Material confirmation	Potential risks
It is necessary to confirm whether the length, width and thickness of the electrode meet the process standards	Poor jelly roll coverage, size does not meet requirements
It is necessary to confirm whether the length, width and thickness of the diaphragm meet the design specifications	Jelly roll size does not meet requirements, finished battery performance affected
It is necessary to confirm whether the type and size of the winding needle meet the process requirements	Battery deformation, jelly roll size does not meet requirements
It is necessary to confirm whether the termination tape meets the process requirements	Jelly roll thickness and appearance unqualified

2. Parameter confirmation	Potential risks
It is necessary to confirm whether the winding speed meets the process requirements and record it	Electrode broken and battery deformation
It is necessary to confirm whether the tension of the positive and negative electrodes is too large and record it	Electrode broken and battery deformation
It is necessary to confirm whether the tension of the diaphragm is too large and record it	Battery deformation

3. Confirmation of the appearance and size of the jelly roll	Potential risks
It is necessary to confirm whether the inner and outer layers of the jelly roll are aligned	Internal short circuit, poor packaging
It is necessary to confirm whether the height of the tab glue meets the design requirements	Poor packaging, unqualified size
It is necessary to confirm whether the height, width and thickness of the jelly roll meet the process standards	Cannot be put into the shell, unqualified appearance, finished battery size exceeds the standard
It is necessary to confirm whether the tab margin and center distance meet the design requirements	Poor packaging, unqualified size, affecting use
It is necessary to confirm whether there is a possibility of contact between the negative electrode and the aluminum-plastic film layer	Al layer is corroded, battery leakage, flatulence
Disassembling the battery, it is necessary to confirm whether the end position of the electrode is correct	Unqualified size, internal short circuit
When disassembling the battery, it is necessary to confirm whether the diaphragm and the negative electrode, and the negative electrode and the positive electrode are completely covered	Low capacity, lithium deposition, internal short circuit
Disassembling the battery, it is necessary to confirm whether the positive electrode, negative electrode, and diaphragm are wrinkled	Poor battery interface, lithium deposition
Disassembling the battery, it is necessary to confirm whether the first fold of the positive electrode and the negative electrode are broken or transparent	Large battery internal resistance, low capacity
Disassembling the battery, it is necessary to confirm whether there is contact between the exposed Al foil and the negative electrode material	Poor safety performance

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