TY - JOUR A1 - Tuma, Dirk A1 - Shafi, P. M. A1 - Mohapatra, D. A1 - Reddy, V. P. A1 - Dhakal, G. A1 - Kumar, D. R. A1 - Brousse, T. A1 - Shim, J.-J. T1 - Sr- and Fe-substituted LaMnO3 Perovskite: Fundamental insight and possible use in asymmetric hybrid supercapacitor N2 - The symmetry or structural stability of ABO3-type perovskite oxides depends largely on the size of ‘A’ and ‘B’ cations, which determines the material properties. The partial substitution of these cations may be used to tune these properties. The ionic sizes and valence states of the cations play an important role in improving the prop- erties of perovskite. In this study, the substitution of La3+ with Sr2+ with a larger ionic radius and Mn3+ with Fe3+ with a similar ionic radius favored both the crystal symmetry and the mixed ionic–electronic conductivity of the perovskite. Electrodes based on La0.7Sr0.3Mn0.5Fe0.5O3 (LSMFO55) exhibited a faradaic behavior with a specific capacity of 330 C g−1 (92 mAh g−1 ) at 12C rate, while this electrode maintained a capacity of 259 C g−1 at 240C (charge or discharge in 15 s). Additionally, exohedral carbon nano-onions (CNO) were introduced as a negative electrode to design an asymmetric hybrid supercapacitor (AHS) with a widened cell voltage. The use of CNO as a negative electrode in the AHS improved the rate capability drastically compared to the use of rGO. This device maintained a good energy density even at an extra-high charging rate (600C) owing to its outstanding rate capability. The high-rate performance of the LSMFO55//CNO AHS can be elucidated by successful fabrication with a mixed ionic–electronic conductive positive electrode and a CNO negative electrode. Tuning the electronic and ionic conductivities by cationic substitution and adopting an appropriate carbon-derived negative electrode (such as CNO) can provide a practical high-rate hybrid device using various perovskites. KW - Perovskite KW - Carbon nano-onion KW - Supercapacitor PY - 2022 DO - https://doi.org/10.1016/j.ensm.2021.11.028 SN - 2405-8297 VL - 45 SP - 119 EP - 129 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-54882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eshetie Kidie, A. A1 - Dhakal, G. A1 - Sahoo, S. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Interlayer spacing-controlled carnation flower-like microstructure of nickel-manganese layered double hydroxide for enhancing hybrid supercapacitor performance N2 - Energy harvested from intermittent sources can be stored in supercapacitors for high-power delivery with long cycling stability. Binary layered double hydroxide (LDH) materials have great potential for hybrid supercapacitor applications owing to their mixed and tunable charges and layered structure. This study presents carnation flower-like, 3D micro-structured NiMn-LDH prepared by a facile single-step hydrothermal synthesis using hexamethylenetetramine to produce hydroxides. The 3D structure was assembled from ultrathin 2D NiMn-LDH nanosheets, and the largest interlayer spacing was obtained by optimizing synthesis parameters, such as Ni:Mn molar ratio and reaction temperature, ensuring a fast diffusion and thus the best energy storage performance. The optimized NiMn-LDH electrode delivered a high specific capacity of 612 C/g with an excellent rate capability of 67% at 20 A/g in a three-electrode test. An asymmetric device assembled using NiMn-LDH and reduced graphene oxide as positive and negative electrodes provided a high energy density of 60.0 Wh/kg and power density of 17.7 kW/kg with 90.4% capacity retention after 10,000 charge–discharge cycles. This superior result highlights the potential industrial applications, such as portable electronics and trams. KW - Supercapacitor KW - Hydrothermal synthesis KW - Interlayer spacing PY - 2024 DO - https://doi.org/10.1016/j.jiec.2023.12.032 SN - 1226-086X VL - 133 SP - 550 EP - 560 PB - Elsevier BV CY - Amsterdam AN - OPUS4-60472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -