Solid-state lithium battery chemistries achieving high cycle performance at room temperature by a new garnet-based composite electrolyte

Abstract LiBr has been incorporated into Li 6.25 La 3 Zr 2 Al 0.25 O 12 garnet matrix to develop a new garnet-based composite electrolyte through high-energy ball milling followed by solid-state reaction. Of importance to note in the composite materials is joint occurrence of anion doping at Li 6.25 La 3 Zr 2 Al 0.25 O 12 bulks and lithiated interface at Li 6.25 La 3 Zr 2 Al 0.25 O 12 grain boundaries. Lattice distortion based on Br − substitution at partial O 2− sites and high densification resulted from mergence effect of LiBr have been detected in the composite electrolytes. Li-ion conductivity and transport kinetics are thereby enhanced after LiBr incorporation. Also, LiBr addition into Li 6.25 La 3 Zr 2 Al 0.25 O 12 causes the appearance of finely microporous feature for the composite materials without compromising pellet densification, which can favor interfacial contact and Li-ion motion between the composite electrolytes and electrode. A full cell with a Li metal anode, the newly developed solid electrolyte, tiny amount of liquid electrolyte, and a LiCoO 2 cathode has been assembled in sequence. High cycle stability of the full cell can be derived from capacity retention of 91.8% and high discharge capacity of 111.6 mAh g −1 after 70 cycles at room temperature. Consequently, favorable contributions of LiBr addition towards solid-state cell system can be further ascertained.