Akademik Veri Yönetim Sistemi
Journal of Energy Storage, cilt.141, 2026 (SCI-Expanded, Scopus)
Supercapacitors are attractive energy storage technologies due to their high-power density, rapid charge/discharge rates, and durable charge/discharge cycles. However, conventional cobalt-based electrodes are costly, toxic, and environmentally unsustainable, highlighting the need for alternative materials. Owing to their layered structures, multiple oxidation states, and high charge transfer efficiency, layered double hydroxides (LDHs) have become prominent candidates for advanced supercapacitor electrodes. In this study, cobalt-free MnNiZn-based LDHs with thin-layered morphologies were synthesized via a solvothermal method in ethanol using ZIF-8 nanocrystals as sacrificial templates. Post-synthesis treatment with 2 M KOH resulted in the intercalation of carbonate anions (originating from trace impurities in KOH), replacing nitrate ions between the layers. Under identical synthesis conditions, four different LDH structures and ZnMn2O4 structure were prepared by varying the amounts of manganese and/or nickel nitrates to obtain different metal concentrations. Among these, Mn2Ni2Zn-LDH—formulated as Mn0.083Ni1.596Zn1.000 based on ICP-MS analysis—exhibited the best electrochemical performance. The BET surface area of Mn2Ni2Zn-LDH exhibited a modest increase following treatment with 2 M KOH, reaching to 102 m2/g. It achieved a high specific capacity of 312.7 mAh/g (∼2251 F/g) at 1 A/g, with a rate capability of 80 %, demonstrating excellent capacitive behavior and good reversibility. This demonstrates how precise compositional tuning, with trace amounts of Mn(III) content, can lead to significant improvements in specific capacity and overall electrochemical performance. Furthermore, the electrochemical performance of Mn2Ni2Zn-LDH was evaluated in an asymmetric supercapacitor device, where it served as the positive electrode and biomass-derived activated carbon (AC) was used as the negative electrode. The device delivered an energy density of 50.9 Wh/kg at a power density of 435 W/kg within a 0–1.7 V operating window, with a specific capacitance of 126.9 F/g measured at a current density of 0.5 A/g. After 5000 charge-discharge cycles, 76.2 % of the initial capacity was retained, indicating good long-term stability. These results suggest that the synthesized MnNiZn-based LDH materials are promising candidates for developing cobalt-free, cost-effective, and environmentally friendly high-performance electrodes for next-generation supercapacitor applications.