Battery Formation and Pack Methods: An Overview

Lithium-ion batteries undergo a three-step production process involving liquid injection, cell formation, and aging. After capacity classification and various tests, they are sorted and graded before packaging and shipment. This article explores ion battery pack PACK methods and compares different PACK approaches.

Understanding Battery Formation

Li-ion batteries are discharged when initially assembled and must be charged for activation. The first charge, referred to as cell formation, activates the battery's active materials. This process is complex and significantly impacts battery performance.Battery recycling machine During the first charge, a thin passivated layer, known as the solid electrolyte interface film (SEI film), forms at the phase interface between the carbon anode and the electrolyte.

Battery capacity division is a procedure involving battery charging, discharging, and testing to determine the battery's capacity. Only batteries with tested capacities meeting or exceeding the designed capacity are considered qualified.cylindrical battery pack mahcine The process of segregating qualified batteries based on capacity testing is known as capacity segmentation.

Importance of Battery Formation and Capacity Segmentation

Battery formation, capacity division, and testing systems are crucial aspects of the back-end process. Battery cells are charged and discharged to initiate the battery and activate its active materials. While the principle of lithium battery formation is intricate,cell stacking machine it significantly impacts battery performance. Additionally, the choice of power connector, acting as a switch between the battery and external connections, also influences battery performance. High-quality battery terminals can enhance lithium battery performance.

Battery formation is a charging process that does not involve discharging the battery cells, making it possible to use a separate charger during this process, referred to as a battery forming machine or battery forming cabinet. Some battery forming processes involve multiple charges, followed by a post-forming capacity separation process, which includes charging and discharging the battery cells.

Once batteries are formed and charged, they must be discharged. Charging and discharging are performed using a charger/discharger with charge/discharge functionality. Capacity classification ensures the screening and grouping of qualified batteries, optimizing the battery pack's consistency. The choice of connector for the battery formation device is crucial as it serves as the device for activation and compliance checking.

Three Battery Formation Methods

In response to industry demands for energy efficiency and improved product consistency, battery formation methods have evolved from traditional single-point formation to series formation and composite formation. Three primary battery formation methods include single-point battery formation, composite battery formation, and series battery formation.

1. Single-Point Battery Formation

Single-point battery formation represents the most traditional approach. In this method, each battery is individually charged and discharged using separate modules, and there is minimal interaction between individual batteries.

2. Composite Battery Formation

The objective of composite battery formation is to control input costs while ensuring product consistency. This method involves connecting a series of batteries (the exact number varies based on the design) for simultaneous charging, ensuring each battery draws an identical current. To maintain traditional single-cell charge/discharge control and battery constant voltage functionality, a bypass control module is added at both ends of each cell.

3. Series Battery Formation

Series battery formation is an approach that has gained traction in the industry. In this method, an entire series of batteries is connected in series and then charged and discharged together. For example, you can obtain 24V by connecting two 12V lithium-ion batteries in series. This method does not facilitate constant voltage charging and discharging of individual batteries.

Series battery formation can be further divided into two methods. The simpler approach involves connecting all batteries in series, where any abnormality in a single cell halts the entire series. The other method involves bypass control of individual batteries within the series. If one cell experiences an issue, the bypass mechanism skips the abnormal cell, allowing other cells to charge and discharge normally.