Charging efficiency improvement by structuring lithium battery electrodes

摘要

For atomic intercalation into an infinite long solid electrode, Haftbaradaran et al. [Appl. Phys. Lett. 96, 091909 (2010)] have pointed out that a coupling between internal stresses and activation energy for diffusion may result in surface locking instability accompanied by very large stresses near the electrode surface, significantly limiting the overall charging rate for high energy density lithium batteries. In the present study, we applied this model to the cylindrical electrode with finite length and found that free ends of the electrode may help to release surface stress within certain extent to each of them and postpone the surface locking of diffusion to occur. Following this finding, we further created parallel grooves on the electrode surface and quantitatively investigated the influences of the groove size and interval to the stress distribution and critical charging current density under galvanostatic charging and discharging conditions. It shows that such treatment of surface slotting to electrodes can significantly decrease the mechanical stresses during atomic intercalation and extraction, and improve the electrode charging efficiency, providing some beneficial inspirations to the Lithium battery technology.