Synthesis of single phase cubic Al-substituted Li7La3Zr2O12 by solid state lithiation of mixed hydroxides

Substituted Li7La3Zr2O12 (LLZ) with cubic garnet type structure is a promising candidate for solid state electrolyte in all-solid-state batteries. Here we present a novel synthesis route to obtain single phase cubic Al-substituted LLZ. The two step method consists of a co-precipitation of metal hydroxides from aqueous solution as well as solid-state lithiation and crystallization of the dried precipitate. Morphology and chemical composition of precipitated particles were investigated with SEM and EDS. Phase composition of calcined powder was confirmed to be pure phase cubic LLZ via XRD. The temperature dependent lithium ion conduction of a sintered pellet was determined to be 6.3 · 10-5 S/cm at 353 K with an activation energy of 0.58 eV

Mixed copper-zinc hexacyanoferrates as cathode materials for aqueous zinc-ion batteries

Aqueous rechargeable metal-ion batteries have become potentially advantageous for the integration of renewable energy sources into the electric power grid thanks to their high rate capability, low cost, environmental friendliness, and intrinsic safety. In this work, we tried to improve the electrochemical stability of CuHCF and prevent/postpone its aging upon cycling. At first we investigated the phase transformation occurring in CuHCF during intercalation of zinc using XRD, SEM and EDX. We observed that large particles are formed upon cycling, which are depleted from copper and are zinc- or iron-rich. In order to prevent this, we modified the CuHCF structure by partially substituting its transition metals with zinc ions during synthesis. We observed that CuZnHCF mixtures with Cu:Zn ratios of 93:7 exhibited an excellent cycle life up to 1000 cycles, with improved specific charge retention with respect to its CuHCF counterpart. Also in the case of CuZnHCF mixtures the formation of large particles upon cycling is observed, but less extended as in pure CuHCF. It appears that different morphologies of the particles show different compositions in term of zinc, iron and potassium