Li_1.3Al_0.3Ti_1.7(PO₄)₃(LATP) is considered a promising material for all-solid-state lithium batteries owing to its high moisture stability, wide potential window (~6 V), and relatively high ion conductivity (10^-3–10^-4 S/cm). Solid electrolytes based on LATP are manufactured via sintering, using LATP powder as the starting material. The properties of the starting materials depend on the synthesis conditions, which affect the microstructure and ionic conductivity of the solid electrolytes. In this study, we synthesize the LATP powder using sol-gel and co-precipitation methods and characterize the physical properties of powder, such as size, shape, and crystallinity. In addition, we have prepared a disc-shaped LATP solid electrolyte using LATP powder as the starting material. In addition, X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopic measurements are conducted to analyze the grain size, microstructures, and ion conduction properties. These results indicate that the synthesis conditions of the powder are a crucial factor in creating microstructures and affecting the conduction properties of lithium ions in solid electrolytes.

Ni_1/3Co_1/3Mn_1/3(OH)₂ powders have been synthesized in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH using NH₄OH as a chelating agent. The co-precipitation temperature is varied in the range of 30-80°C. Calcination of the prepared precursors with Li₂CO₃ for 8 h at 1000°C in air results in Li Ni_1/3Co_1/3Mn_1/3O₂ powders. Two kinds of obtained powders have been characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analyzer, and tap density measurements. The co-precipitation temperature does not differentiate the XRD patterns of precursors as well as their final powders. Precursor powders are spherical and dense, consisting of numerous acicular or flaky primary particles. The precursors obtained at 70 and 80°C possess bigger primary particles having more irregular shapes than those at lower temperatures. This is related to the lower tap density measured for the former. The final powders show a similar tendency in terms of primary particle shape and tap density. Electrochemical characterization shows that the initial charge/discharge capacities and cycle life of final powders from the precursors obtained at 70 and 80°C are inferior to those at 50°C. It is concluded that the optimum co-precipitation temperature is around 50°C.

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• A kinetic descriptor to optimize Co-precipitation of Nickel-rich cathode precursors for Lithium-ion batteries
  Seon Hwa Lee, Ki Young Kwon, Byeong Kil Choi, Hyun Deog Yoo
  Journal of Electroanalytical Chemistry.2022; 924: 116828.     CrossRef

As precursors of cathode materials for lithium ion batteries, Ni_1/3Co_1/3Mn_1/3(OH)₂ powders are prepared in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH in the presence of NH4OH in air or nitrogen ambient. Calcination of the precursors with Li₂CO₃ for 8 h at 1,000°C in air produces dense spherical cathode materials. The precursors and final powders are characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analysis, tap density measurement, and thermal gravimetric analysis. The precursor powders obtained in air or nitrogen ambient show XRD patterns identified as Ni_1/3Co_1/3Mn_1/3(OH)₂. Regardless of the atmosphere, the final powders exhibit the XRD patterns of LiNi_1/3Co_1/3Mn_1/3O₂ (NCM). The precursor powders obtained in air have larger particle size and lower tap density than those obtained in nitrogen ambient. NCM powders show similar tendencies in terms of particle size and tap density. Electrochemical characterization is performed after fabricating a coin cell using NCM as the cathode and Li metal as the anode. The NCM powders from the precursors obtained in air and those from the precursors obtained in nitrogen have similar initial charge/discharge capacities and cycle life. In conclusion, the powders co-precipitated in air can be utilized as precursor materials, replacing those synthesized in the presence of nitrogen injection, which is the usual industrial practice.

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  Korean Journal of Materials Research.2022; 32(4): 216.     CrossRef
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