Samsung SDI to apply EV battery production technique to smartphone battery

South Korean battery maker Samsung SDI is planning to apply to its smartphone battery production the stacking method it currently uses for the production of electric vehicle batteries.

The stacking method stacks battery materials in layers and Samsung SDI uses this technique currently in the production of Gen 5 EV batteries.

The method replaces the jellyroll method in which the battery materials were rolled. Applying the stacking method instead has allowed Samsung SDI to increase the energy density of its EV batteries, sources said.

Samsung SDI is now working to apply this same technique to batteries it manufactures aimed at smartphones and tablets.

The company will first apply the stacking method on its M Line (which despite the name has 12 lines) at its Cheonan plant in South Korea.

The line will be modified to accommodate stacking __ it previously used the winding method to wind the cathode, separator and anode together.

Samsung SDI has also already built a pilot line that uses the stacking method at its factory in Tianjin, China, sources said. Equipment from local vendor Shenzhen Yinghe Tech is being used at the line, they said.

This pilot line is strictly for testing and mass production will happen at the M Line at Cheonan, they added. Four of the 12 lines at M Line will be modified.

The winding method is convenient in battery assembly and Samsung SDI has been using it for cylinder batteries.

But the downside is that it is impossible for vendors to fully utilize the internal space of the battery and they are prone to swelling after long use. This has been an obstacle for battery companies like Samsung SDI to increase energy density for small batteries.

The successful application of the stacking method will allow the South Korean battery maker to increase energy density by over 10%. Stacking method requires additional equipment such as notching.

Another possibility for the move by Samsung SDI could be to win orders from Apple again, the chief rival of its main customer Samsung Electronics.

Apple uses a multi-cell structure where it connects multiple batteries to boost the battery capacity of its iPhones. These are L-shaped. This is done due to the current limitations of increasing the energy density of small batteries. 

Offering batteries with higher energy density than now will allow Cupertino to avoid this current design and make smartphones lighter with more batteries.

Apple’s main supplier of batteries is China’s Amperex Technology Limited; while LG Energy Solution had also supplied some cells in the past. Samsung SDI had supplied batteries for MacBooks and iPads in the past but is yet to win a deal for iPhones.