  The properties of rechargeable lithium-ion batteries are determined by the
electrochemical and kinetic properties of their constituent materials as well
as by their underlying microstructure. Microstructural design can be leveraged
to achieve a leap in performance and durability. Here we investigate a porous
electrode structure, as a strategy to increase the surface area, and provide
structural stability for Li-metal anodes. The porous architecture consists of a
mixed electron/ion conductor that function as a scaffold for lithium metal
deposition. A new finite element model was developed to simulate the large
topological changes associated with Li plating/stripping. This model is used to
predict the current density distribution as a function of material and
structural properties. A dimensionless quantity that combines Li-ion
conductivity, surface impedance and average pore size is shown to be a good
indicator to predict the peak current density. Preventing current localization
at the separator reduces the risk of cell shorting. The analyses show that the
peak current scales as $(hG)^{1/2}$, where $h$ is the ratio between surface and
bulk conductivity and $G$ is the average pore size. Stability analyses suggest
that the growth is morphologically stable, and that confining Li-plating into
pores can enable high-energy density solid-state batteries. In addition to
optimizing porous electrodes design, this finite element method can be extended
to studying other Li-battery structures.
