Factors affecting Li ion cell performance and what you should know about it's manufacturing.

 

BY    AFZAL YOUSAF

Electric vehicles are the sustainable mode of transportation for the future. As batteries are the source to drive electric vehicles, many companies started to research on batteries and manufacture. Battery energy storage system and cell chemistry of the batteries are under continues upgradation  and people are debating over its performance, efficiency and safety. Apart from cell chemistry, performance of the battery depends on various other factors.

In this article you can read about factors affecting cell performance and things needed to know about li ion cells and its manufacturing.

In Battery energy storage system, apart from battery cell, there are several other components that keeps the system function efficiently. It includes power conversion systems for charging and discharging and power control systems which controls the charging and discharging. Also cooling and other safety arrangements will be there. But here we focus mainly on battery and parameters that affects its performance.

Performance and efficiency of the battery is majorly affected by factors like:-

• Cell Chemistry
• Cell Geometry
• Manufacturing Quality
• Technology to application
• System Integration

Cell chemistry is the combination of compounds used. Performance of the cell largely depends on the compounds used and its chemical reaction. Mixture of right components makes great cell chemistry and improved performance. Geometry of the cell is the shape. There are cylindrical, prismatic, pouch cells etc and cylindrical and prismatic types are widely used in EV applications. Cell geometry plays important role in ease of manufacturing and mechanical stability.

Design of the cell is to move electron from anode to cathode during charging. In Li ion cells, positively charged lithium ions moves through a microporous separator filled with electrolyte that prevents passage of electrons. Negatively charged copper and positive aluminium collector will be there. Homologous surface in this allows li ions to pass easily.

In Li ion battery, Manufacturing quality is one of the most critical factor that determines the performance and efficiency of the battery. But it is not much discussed as it is hardly available in public domain like cell chemistry and geometry. Manufacturing and its quality is often an in-house secret to every manufacturers. This is the thing which differentiates each manufacturers though using same chemistry. But in generally we can say battery manufacturing is divided into four steps.

• Quality control and Electrode production
• Cell stack assembly
• Drying, electrolyte filling, Formatting, ageing and sorting
• Assembling to packs

Operating of battery is a chemical process in which each cell needs to be monitored individually for current, voltage and temperature. Quality and accuracy of Battery management systems ensures safety and performance of overall battery system. Battery manufacturing is not a rocket science but still need good effort and carefulness.

After making cells, it needs to be arranged to form battery pack. Individual cells are combined to cell block using serial or parallel connection. These cell blocks are assembled to make modules with communication port of BMS to measure voltage and temperature. These modules then connected to a rack which have a serial connection to all modules combined and includes a control system. This control system provides current sensors and communication protocols.

All these arrangements and process should be based on IEC Standard terminology or any other standard terminology depending on your country. Technology application is an important part as battery technology is one of the finest invention by human beings and should be executed well commercially to get the best outcome.

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