Study On Performance Of Nickel Phosphide And Its Composites Prepared By Clustered Countercurrent-flow Micro-channel Reactor

Supercapacitor is a new type of energy storage device,which is characterized by its high energy density and power density,and long service life.The electrode material of a supercapacitor will mostly determine its performance.Ni2P material is cheap and has a high specific capacitance performance,and therefore it is a very good supercapacitor material.However,the traditional preparation methods of Ni2P materials are normally very complicated,and the prepared materials often show poor cycling performance.Because the micro-channel reactor has a good performance in the field of nanomaterials preparation,this work proposed a method for preparing Ni2P materials and their composite materials by using a clustered countercurrent-flow micro-channel reactor(C-CFMCR)combining low temperature phosphating.The effects of the preparing conditions on the properties of the materials were studied.The main tasks are as follows.(1)Ni(OH)2 material was prepared by a single countercurrent-flow micro-channel reactor(S-CFMCR).Then,it was reduced to Ni2P in the presence of PH3 and purified by acid etching.By studying the effects of phosphating reaction conditions and S-CFMCR reaction conditions on the prepared materials,it was determined that the temperature of the phosphating reaction was 300℃,the heating rate was 10℃/min,the volumetric flow rate was 40 mL/min,the pH was 13.10,the aging time was 3 h and the drying method was freeze drying,the performance of the prepared Ni2P material was the best.Finally,the preparation process was scaled up to C-CFMCR.The results showed that C-CFMCR had no significant amplification effect.The maximum specific capacitance of Ni2P material could reach～1200 F/g,and the specific capacitance retention ratio was about 65%after 500 charge-discharge cycles.(2)In order to improve the poor cycling performance of Ni2P materials,the prepared Ni2P material was further modified with reduced graphene oxide(rGO)and Co element by C-CFMCR.The optimal doping ratio of Ni2P composites was determined.The results showed that the specific capacitance of the Ni2P/rGO composite with rGO mass content of 8.5%could reach～1500 F/g,and the specific capacitance retention ratio was about 68%after 500 charge-discharge cycles.The specific capacitance of the Ni-Co-P composite with a molar ratio of Ni:Co as 15:1 could reach～1475 F/g,and the specific capacitance retention ratio was about 84%after 500 charge-discharge cycles,showing a good rate performance.Therefore,Ni2P composites,especially Ni-Co-P composites,have been significantly improved in terms of specific capacitance and cycle performance.