Improvement Of Clustered Countercurrent-flow Micro-channel Reactor And Preparation Of Manganese Dioxide Composites

Supercapacitor materials have attracted a lot of interests in the field of energy storage since its discovery.It makes it possible to combine high-power density with high-energy density for energy storage devices,and provides new ideas for energy storage technology.MnO2 has attracted attentions as supercapacitor materials due to its abundant reserves,low price and excellent electrochemical performance.However,pure MnO2 has problems such as high resistance and poor cycling performance.In this study,MnO2 composite was prepared by liquid-phase ion doping method with the micro-reactor technology,and the micro-reactor was improved in the preparation process.The main contents are as follows:(1)Ni-doped MnO2 was prepared by the single countercurrent-flow micro-channel reactor(S-CFMCR),and the effects of different process conditions on the morphologies and the electrochemical properties of the materials were studied.The optimum process conditions were determined:1%of doping concentration,4 h of aging time,40 mL/min of volumetric feeding rate and 220℃ of calcination temperature.The optimized material has an initial specific capacitance of 398 F/g,and the capacitance reserved 85%after 500 cycles of charging and discharging,which was better than that of the material prepared in a beaker under the same conditions.Therefore,it suggested that the large-scale preparation with clustered countercurrent-flow micro-channel reactor(C-CFMCR)is possible.(2)Based on the study of S-CFMCR,the reactor was upgraded to a detachable type of C-CFMCR-2 by introducing a modular structure·The improved reactor consists of a shell,shunts,soft and hard drive interfaces and parallelly distributed capillaries.It can be adjusted freely with the reactor opening size,tube diameter and number of tubes.And it is easy to remove,wash,replace in part,repair and reuse.(3)The micro-mixing experiments disclosed the optimal feeding mode of the modified C-CFMCR-2,and verified the process characteristics that the optimal volumetric feeding rate increased as the opening size increased within a certain range.Ni-doped MnO2 capacitor materials were then prepared by the new C-CFMCR-2 reaction system and the morphology and electrochemical properties of the materials with different magnifications were studied.The pores of the materials were analyzed by N2 adsorption-desorption tests.The results showed that the material mainly consisted pores with a pore diameter of～3.8 nm and the mesoporosity was higher than 80%(pore diameter of 2～50 nm),with a high specific surface area of～148 m2/g.The electrochemical performance tests showed that the composite material prepared by ten times of amplification had an initial specific capacitance of～370 F/g,and the capacitance reserved 91%after 500 cycles of charging and discharging.It is a capacitor material with excellent performance,confirming the potential application value of C-CFMCR-2 process.