The Effects of Vaporized Solid Electrolyte Solution for All-Solid-State Batteries

Abstract

Recently, lithium-ion batteries (LIBs) have been applied to large-scale devices such as electric vehicles and energy storage systems (ESSs), requiring high energy density and long cycle life. The use of organic electrolytes in lithium ion batteries in such large-scale devices has some safety issues. Organic electrolytes have a high ionic conductivity, but there are many risks of leakage, explosion and ignition due to the decomposition reaction of the electrolyte. As a promising solution to this issues, the use of a solid electrolyte have been proposed. In contrast to organic-based liquid electrolytes, all-solid-state lithium batteries (ASLBs) with a solid electrolyte are considered safe because of their non-flammability. These solid electrolytes have the advantages of high stability and high energy density, but they have a disadvantage of very low ionic conductivity at room temperature. In this work, we prepared sheet-type Li6PS5Cl-infiltrated electrode that has high capacity, even though it has high loading value. We propose two methods to ensure that SE materials are evenly distributed and sufficiently infiltrated into the porous structures of LIB electrode. First, we aimed to reveal the effects of solid electrolyte solution vaporization on the solid electrolyte content in the thick electrode for ASSBs. The performance of the cells at different temperatures were compared. Elevated temperature of SE solution arrive at vaporization point and it result in molecular motion, and it makes more LPSCl infiltrated into electrode. The NCM622 electrode infiltrated LPSCl at 90oC show reversible capacity of 177mAh/g (5.5mg/cm2) and 136mAh/g (17mg/cm2) at 0.05C, 55oC. We also prepared three different active materials having different particle size. The porous electrode which is made by mixing different sized active materials(DS-AM) absorbs SE solution. This absorb effects explain the capillary phenomena. The mixed DS-AM electrode demonstrated higher capacity than non-mixed DS-AM electrodes due to the improved ion transport path.