The Challenge of 3D All Solid State Li-Ion Battery

Demonstration of all-solid state 3-dimensional (3D) Li-ion batteries has been a long standing goal for numerous researchers in the battery community interested in developing high power and high areal energy density storage solutions for variety of applications. The basic idea is to use the 3D geometry to maximize the volume of active material per unit area, while keeping its thickness sufficiently small to allow for fast Li diffusion. The 3D approach also leads to high electrode/electrolyte interface area, which should prove beneficial by lowering the local current density and therefore the charge transfer resistance, assuming that the interface is stable against parasitic reactions and breakdown. While simple conceptually, realizing working all solid state Li ion batteries has proven to be a significant challenge.  Specifically, the physical vapor deposition processes which have been successfully implemented for planar, thin film solid state Li ion batteries, fail miserably when applied to 3D substrates, particularly with high aspect ratio features. In our presentation, we will describe the structure and performance of all solid state 3D Li ion batteries fabricated by physical vapor deposition.  Although these can be charged and discharged at low C-rates, their capacity decreases rapidly at higher C-rates. In our presentation we will discuss the underlying reasons for the poor performance and demonstrate how these problems can be addressed using atomic layer deposition, a thin film deposition method compatible with high aspect ratio geometries.