Intensive efforts have been taken to decrease the over-potentials of solid-state lithium batteries. Lowering the anode-electrolyte interface resistance is an effective method. Compared to simply improving the interface contact, constructing both ionically and electronically conductive phases within the anode demonstrates superior improvement in reducing the interface resistance and promoting electrochemical stability. However, complex preparation procedures are usually involved in the construction of the conductive phases and the loading of metallic lithium. Herein, a composite anode containing metallic lithium and well-dispersed ionically conductive Li3N and electronically conductive components (Fe, Fe3C, and amorphous carbon) shows an effective decrease in lithium stripping/plating over-potentials at high current densities of up to 3 mA cm-2. The unique dual ionically and electronically conductive phases exhibit good cycling stability for 3000 h. A full battery with the composite anode and a LiFePO4 cathode also demonstrates decent performance. This work confirms the importance of constructing dual conductive phases that are electrochemically stable to Li and will not be consumed during the electrochemical reaction and provides a facile preparation method. The new knowledge discovered and the new methods developed in this work would inspire the future development of new Li-containing composite anodes.
Keywords: composite anode; electronic conductivity; ionic conductivity; lithium battery; solid-state battery.