Wednesday, 12 October 2022
Z. Yang, S. Cora, V. Briselli (University of Massachusetts Boston), and N. Sa (Argonne National Laboratory)
The increasing demand for higher capacity energy storage technologies is rapidly becoming an important consideration in the development of EV and related energy storage devices. Silicon is one promising solution as an earth-abundant element with a higher capacity than the more commonly used graphite anode of a lithium-ion battery. However, silicon anodes face unique challenges with volume expansion, notable during lithium ion intercalation and the stability of the SEI layer. To solve this problem, some recent research efforts discovered introducing a co-intercalation ion in the traditional lithium electrolyte Gen2 increases the coulombic efficiency, capacity, and stability of the silicon anode, but its mechanism of action remains unclear.
In this work, in combination with experimental measurements we demonstrate the use of Newman's P2D Lithium Model in COMSOL together with the Butler-Volmer equation and concentrated solution theory to describe cation co-intercalation into the porous silicon anode material. Experimental data indicates that phase formation and transformation coincide with ion insertion, as reflected in the current response signal. Both the original ion intercalation and the foreign ion intercalation are reflected by CV generated by our model under the influence of model parameters, such as the variable speed of potential changed per second. As designed, our model can be extended towards general application in the cointercalation system and understanding of the foreign ion effect.
