- Category: Technology
03 Oct 2012
- Published on Wednesday, 03 October 2012 09:48
- Hits (1646)
While adding nickel to the electrode of a lithium-ion battery can improve its energy storage capacity, it blocks the flow of lithium-ion, decreasing its rate of discharge.
Scientists at the Department of Energy’s Pacific Northwest National Laboratory took a closer look at battery materials at the nano scale and found that nickel forms a physical barrier that impedes the movement of lithium ions.
The researchers, led by materials scientist Chongmin Wang, created high-resolution 3-D images of electrode materials made from lithium-nickel-manganese oxide-layered nanoparticles.
They found that nickel formed clumps at certain spots in the nanoparticles, blocking the channels through which lithium ions normally travel during a battery’s charge and discharge cycle.
“We were surprised to see the nickel selectively segregate like it did. When the moving lithium ions hit the segregated nickel rich layer, they essentially encounter a barrier that appears to slow them down,” said Mr. Wang.
The 3-D images showed that in the electrode layers, the manganese and oxygen atoms form rows like a field of cornstalks. The lithium ions and nickel move in the channels between these stalks during the charge and recharge cycle. Unfortunately, with each cycle, nickel gradually accumulates in these channels, forming a block that impedes the movement of lithium.
According to Mr. Wang, the barrier is likely formed during the manufacturing process and finding a way to prevent it could improve the performance of future lithium-ion batteries.