Sintered electrode full cells for high energy density lithium-ion batteries

Abstract

Increasing the energy density of lithium-ion batteries at the electrode and cell level is necessary to continue the reductions in the size and weight of battery cells and packs. Energy density improvements can be accomplished through increasing active material density in electrodes by decreasing porosity and removing inactive additives, as well as by using thicker electrodes that reduce the relative fraction of separators and current collectors in the cell. This paper describes the fabrication of sintered electrodes comprised of only electro-active material toward the goal of thick electrodes free of binders and conductive additives. The electrodes reported herein have no inactive additives in the electrode, > 62% active material volume fraction, and high thicknesses of > 500 µm. The high capacity of these electrodes presents challenges for material characterization and extended cycling. In particular, lithium metal anodes limit the performance of sintered electrode cells at > 1 mA cm−2, a relatively low rate for these thick electrodes. In this work, full Li4Ti5O12/LiCoO2 (LTO/LCO) sintered electrode cells with total combined thickness of anode, separator, and cathode of up to 2.90 mm have been successfully fabricated and electrochemically evaluated. These full cells have improved stability and high areal capacities, as high as 45 mAh cm−2 capacity at 1.28 mA cm−2.