Study On Preparation Of Nickel/Cobalt Based Composites By Micro-impinging Stream Reactors And Their Electrochemical Performance

As a new type of energy storage device,supercapacitors have attracted much attention due to their excellent electrochemical properties.But their low energy density has limited their applications in many fields.Finding high performance electrode materials is an effective way to improve supercapacitors.Ni-Co-S composite material has good conductivity and high specific capacitance,which is very suitable for electrode materials.Traditional co-precipitation is rarely used as the synthesis method of Ni-Co-S composites due to the non-uniform mixing.However,micro-impinging stream reactors(MISR)have great advantages in promoting the micro-mixing efficiency.In this work,MISR was used to prepare nickel-cobalt based composites.The main contents are as follows:MISR was used to prepare Ni-Co-S composites as electrode materials,and the effects of the raw material ratio and operating conditions were investigated.As the end,the optimal ratio of nickel-cobalt atoms in the feed was determined to be 2:1,the feed flow was 120 mL/min,the aging time was 3 h,and the drying method was freeze-drying.Charge and discharge were carried out at the current density of 1 A/g,and the initial specific capacitance could reach～1500 F/g.After 500 cycles,the specific capacitance retention rate remained about 68%.Using a two-stage micro impinging stream reactor(TS-MISR)and hydrothermal reduction method,the composites could grow evenly on the reducted graphene oxide(rGO),and the best performance was achieved when adding 0.5 mg/mL of graphene oxide(GO)and being reducted for 6 h under 180℃.When the charge and discharge current density was 1 A/g,the initial specific capacitance could reach～1480 F/g and the cycling performance was improved.After 500 cycles,the specific capacitance retention rate was about 73%.The ordered mesoporous Ni-Co-S composites with hollow spheres were prepared by a two-step synthesis method using MISR combined with high pressure hydrothermal method.At the current density of 1 A/g,the initial specific capacitance of the material could reach～1537 F/g,and the retention rate of specific capacitance after 500 cycles of charging and discharging was about 84%.When the current density of 20 A/g was used for charging and discharging,and the retention rate of specific capacitance was about 71.2%,indicating the excellent multiplying performance of the material.