Grant: Collaborative Research and Development Grants

Our three year project aims to develop new all-solid-state batteries to be used in electrical vehicles (EVs) and portable technologies with high energy density and long term stability, by using lithium metal as negative electrode. Metallic lithium is an ideal anode material since it has the highest theoretical capacity (3860 mA/g) and the lowest electrochemical potential (-3.04 V vs NHE). However, it is not yet widely used in commercial applications due to its high chemical reactivity. During battery cycling using standard liquid electrolyte the liquid electrolyte may degrade, thereby limiting the lifetime of the battery. In addition, some inhomogeneities of solid electrolyte interface can cause uncontrolled dendrite formation during the deposition of lithium metal. This side reaction can be the cause of dangerous short-circuits for the battery. A solid electrolyte based on a ceramic as lithium ionic conductor physical barrier may address this challenge. First we will explore new solid state synthesis of superionic ceramic solid electrolytes by using a hot-press method that is able to heat (up to 1500° C) and press (up to 25 tons/cm2) the precursors, at the same time obtaining highly dense solid electrolyte pellets. In parallel we will investigate new chemical (e.g. solution drop-by-drop deposition) and physical methods (e.g. metal sputtering) that can protect lithium metal from possible side reactions with our new materials. Then we will prepare new highly dense composites by mixing different cathode materials (at first standard LiFePO4 and high energy LiNiMnCoO2) and new superionic ceramic solid electrolytes in a hot press machine. These new sandwich like composites will be tested in a full cell using protected lithium metal as negative electrode. The batteries will be optimized for operation at room temperature. Finally we will investigate a new class of polymer-in-ceramic which will make the battery flexible.