The new study is based on the following hypothesis. What happens if you throw silicon particles in, fragment them, and fix them later?
As mentioned earlier, fragmentation is a problem because it essentially causes small chunks of silicon to fall off the grid and no longer make contact with the system that transfers charge to and from the electrodes. These particles are often partially filled with lithium, which prevents the lithium from being recycled and reduces the battery’s capacity even if there is sufficient electrode material.
The researchers, all based at Stanford University, determined that there was a way to nudge these pieces back into the electrical system, demonstrating that they could significantly restore the capacity of severely degraded batteries.
put things together
The idea behind the new research was that it might be possible to attract pieces of silicon to electrodes, or at least other materials connected to a charge-handling network. The fragments within the anode should have no net charge themselves. There, when the lithium abandons the electrode, it should return to solution. However, it is unlikely that the lithium is evenly distributed throughout the fragment, resulting in a net neutral but polar material with regions of high and low electron density. And polar substances move in a non-uniform electric field.
Additionally, the electrodes have a nonuniform and chaotic structure at the nanoscale, which generates a nonuniform electric field when a voltage is applied. Depending on the local structure, it can attract or repel some particles. However, since these are mostly within the structure of the electrode, most of the silicon debris can quickly hit other parts of the electrode. This may then reestablish the connection of the electrode to the current handling system.
To demonstrate that what should happen in theory actually happens inside an electrode, the researchers began by taking a used electrode and brushing part of its surface into a solution. They then applied a voltage to the solution and watched as small particles from the battery began to move toward one of the electrodes they used to apply the voltage to the solution. So things worked as expected.
