Aqueous Based Cathode Slurries for Use in Three-Dimensional Lithium-Ion Batteries

Aqueous Based Cathode Slurries For Use in Three-Dimensional Lithium-ion Batteries

Derek C. Johnson, Matthew T. Rawls, and Amy L. Prieto

Chemistry Department, Colorado State University

Prieto Battery, Inc., Fort Collins, CO

                Traditional two-dimensional planar based lithium-ion batteries have the inherent trade-off between energy and power density.  If one is designing a high power density cell, the electrode thickness is typically reduced resulting in a decrease in energy density.  Conversely, if the cell is designed for high energy density, power density is diminished because of an increase in lithium-ion diffusion length as a result of an increase in electrode thickness.  The use of a three-dimensional (3D) architecture is intriguing because it allows a significant decoupling of energy and power density.  This is accomplished because 3D architectures allow the utilization of a third dimension without inducing damage or instability into the electrodes.  Additionally, a 3D architecture calls for the interdigitation of the negative and positive electrodes thereby reducing the lithium-ion diffusion length by a factor of 10-100.  While the use of 3D battery architectures promises a significant leap forward in terms of performance, many technical challenges must be overcome in order to fabricate a functional cell.  Our work is focused on using electrodeposition to synthesize 3D anode structures to which a conformal solid-state electrolyte coating is deposited.  A significant challenge we have faced is the incorporation of a nanoparticle cathode slurry into the 3D structure without damaging the solid-state electrolyte, thus causing a short.  The most pressing problem has been the incompatibility of the slurry solvent with the solid-state electrolyte.  We thus have developed an aqueous based slurry that when dried results in a low impedance, structurally robust positive electrode that does not damage the solid-state electrolyte.  The solid-state performance of this electrode with nanoscale LiFePO₄ as the active material will be presented.