Type of prismatic cells- winding and Z stacking | Part 2

Part 1 of this article discussed the internal structure and structural change with cycling and its effect on the expected cycle life of Winding and Z Stacking Type of Prismatic Cells.

Part 2 builds up on the previous article. It compares the performance of the two types of Prismatic cells for the Discharge Capacity that is directly linked to the round-trip efficiency and the temperature rise for the two types of Prismatic cells at various C rates of discharge.

Winding Type Cell

Voltage vs. Discharge Capacity Curve – Winding Type Cell

Laminated (Z Stacking) Type Cell

Voltage vs. Discharge Capacity Curve – Laminated (Z Stacking) Type Cell

The above data has been taken from a cell manufacturer. The above data shows that the Laminated (Z stacking) type cell has better discharge capacity at 1C and 2C discharge rate when compared to its base discharge capacity of 0.5C discharge rate (which is considered as 100% capacity). Better discharge capacity translates to higher round trip efficiency of the cell and lower energy losses during discharge (in terms of the heat), leading to lower temperature rise during discharge operation. Hence, one can see that the rise in cell temperature of the laminated (Z stacking) type cell is also significantly lower than that of the winding type cell.

Similarly, let us see the voltage curve of the two types of Prismatic cells at various temperatures from -20°C to 60°C.

a. Winding Type Cell

b. Laminated (Z stacking) Type Cell

Since Lithium-ion cells perform very well at 25°C, the capacity delivered at 25°C is considered 100% capacity, and relative discharge capacity is measured in both winding-type and laminated (Z stacking) type cells.

It can be observed that Laminated Z-Stacking Type cells have better capacity at very low and very high temperatures.

Additionally, this cell manufacturer has added a special electrolyte to allow the cell to perform well in low-temperature operation, and hence, >94% capacity is delivered at -25°C.

About the author

Rahul Bollini is an R&D expert in Lithium-ion cells with 9 years of experience. He founded Bollini Energy to assist in deep understanding of the characteristics of Lithium-ion cells to EV, BESS, BMS and battery data analytics companies across the globe. Rahul can be reached at +91-7204957389 and bollinienergy@gmail.com.

Also read: Type of prismatic cells- winding and Z stacking | Part 1