Synthesis of modified nickel iron layered double hydroxides to enhance electrochemical properties for supercapacitor

Abstract

This research aimed to synthesize Mn-doped NiFe LDHs in order to decrease resistivity, which can result in an increase in specific capacity. Mn-doped NiFe LDHs were synthesized using simple coprecipitation method at 50 oC for 6 hours. Their characteristics were confirmed by ICP, XRD, SEM-EDX and FTIR. Electrochemical measurements such as CV and GCD were employed to evaluate their specific capacities. Current voltage relationship and EIS were used to analyse electrochemical properties and resistivities. Through the doping manganese, the specific capacity could be altered. Investigated by CV, the specific capacity of Ni: Fe: Mn 3: 2: 0.98 and 3: 2: 1.7 possessed the electrical capacities of 48.58 F/g and 45.86 F/g that were a 2-fold increase as compared to the 24.72 F/g of NiFe LDH. Similar to the trend found from CV, the specific capacities obtained from GCD increased from 89.32 F/g of NiFe LDH to 203.3 F/g and 207.6 F/g of Ni: Fe: Mn 3: 2: 0.98 and 3: 2: 1.7, respectively. The higher capacity of Mn-doped LDHs might relate to the lower ohmic resistivity. The ohmic resistivity of doped LDH was approximately 4.5 times lower than that of NiFe LDH. The charge transfer resistance of NiFeMn LDH 3: 2: 1.7 was undetected. This work can demonstrate that doping with Mn can increase specific capacity from the decrease of resistance in LDH.