Multi-Physics Simulation for Morphology Design of Si Anode

Abstract Due to a constant increase in the usage of portable battery power storage and delivery systems, there is a constant need for innovation in the area of battery design. One such possible innovation is the use of Silicon (Si) as the anode material in Lithium-Ion Batteries (LIBs). While Si is a much better anode material than the traditionally used graphite anode, its usage comes with its own issues. The intercalating mechanism in Si anodes for Li ion storage, causes an increase in the specific capacity of battery along with significant variation in the volume of Si during the charge/discharge cycling. Volumetric variations of up to 300% are observed during the lithiation/delithiation in the Si anode which results in the development of massive internal stresses in the anode. These internal stresses are observed to cause delamination of the anode from the metal substrate and also the cracking within the anode material itself, which ultimately decreases the capacity of the battery. A possible solution to this problem is to design the morphology of nickel backbones in Si anode to reduce the intensity of the internal stresses and therefore the resulted failure and capacity degradation. In this paper, multiphysics simulation based on finite element analysis is developed to understand and quantify the effect of the morphology of nickel backbone on the lithiation induced stress in the Si anode. A convex and concave anode structure, along with a flat design for comparison, will be simulated for different lithiation/delithiation rates, using the FE model and the FE analysis will be conducted to investigate the changes in the corresponding stresses in Si layer, the cracking pattern and the delaminated area. It is expected the developed multiphysics FE simulations can inform the morphological design of anode to minimize the mechanical degradation and reduce capability loss.