(157f) Mathematical Model for Electrochemical Insertion of Lithium in Nanostructured Silicon Electrodes

Abstract:

Silicon, germanium etc. are presently being pursued as potential anode materials for lithium-ion batteries owing to their high gravimetric (mAh/g) and volumetric capacities (mAh/L) compared to existing state of art graphite, for high energy and high power applications of the future [1]. One of the critical challenges is to overcome particle fracture resulting from internal stresses, developed during lithium intercalation. Recent experimental studies have demonstrated that use of nano-size electrodes help in minimizing insertion induced stresses due to facile strain relaxation [2]. The theoretical framework has been earlier described by several researchers [3-6] but these models have been used to study intercalation induced stresses for materials whose volume change during lithiation is minimal (~6-8%) compared to high capacity materials such as silicon (~300%).

In this talk, development of a transient 1D axisymmetric model to simulate lithium insertion in different type of nanostructured Si electrodes will be presented. The physics of the model includes lithium transport, chemical and elastic strains, Li transport inducted stresses, and volume associated expansion. Case studies on constant current lithiation of different nanostructures, e.g. nanowires [2], nanotubes [7] and core-shell structures will be discussed [8]. Finally, a comparative study will be presented with respect to mechanical stability during lithium insertion among the different nanostructures.

Acknowledgement:

The financial support for this work provided by Applied Material Inc. is acknowledged.

References:

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