Preparation And Properties Of ?-MoO₃ And Its Composite Capacitor Materials

With the development of electronics industry and the widespread use of electronic products,the market demand for high capacitance performance supercapacitor is becoming urgent increasingly.As a kind of transition metal oxide,?-MoO₃ can be used as a high-quality capacitor material because of its unique layered structure,which is beneficial to ion intercalation and deintercalation,as well as its simple preparation and low cost.It has broad application prospects in the field of electrochemistry.In this paper,?-MoO₃ is prepared by different methods,and the optimal preparation process for?-MoO₃ is obtained by changing the conditions.The electrochemical performance of?-MoO₃ is improved by composite method to obtain high-performance?-MoO₃ composite capacitor material.?1??-MoO₃ is successfully prepared by hydrothermal method and direct calcination method respectively.The effects of preparation method and molybdenum source on the structure and capacitance of?-MoO₃ are investigated.In the hydrothermal method,the effects of acid and electrolyte on the structure and capacitance of?-MoO₃ are further investigated.The optimum process for preparation of?-MoO₃ by hydrothermal method is as follows:ammonium molybdate is used as the molybdenum source,HNO₃ provides acidic condition.Under the premise of foamed nickel as a collector,the electrochemical performance is best when neutral Li₂SO₄ is selected as electrolyte.At the current density of 0.5 A g^-1,it is also found that the performance of the flake?-MoO₃ capacitor prepared by direct calcination method is 226.3%higher than that of the rod-structure?-MoO₃ prepared by hydrothermal method(specific capacitance is 81.56 F g^-1),which can reach 184.60 F g^-1.?2?The?-MoO₃ is prepared by hydrothermal method and then calcined.The effect of calcination on its structure and capacitance is investigated.The results show that the structure and electrochemical properties of?-MoO₃ have changed significantly after calcination.After calcination,the polarizability of the Mo-O bond and the crystallinity of the particles increase,and the?-MoO₃ particles significantly increase,exhibiting better capacitance characteristics and cycle stability.At the current density of 0.5 A g^-1,the specific capacitance is increased by100.5%compared with that before calcination,reaching 163.56 F g^-1,which is similar to the?-MoO₃ specific capacity(184.60 F g^-1)prepared by direct calcination method.Therefore,this preparation method can be applied to the subsequent preparation of?-MoO₃/rGO composites.?3?GO is prepared by the modified Hummers method,and rGO is further prepared by hydrothermal reduction method and vacuum thermal reduction method,respectively.The results demonstrate that the specific capacitance,solution internal resistance and cycle retention of rGO prepared by hydrothermal reduction method are larger than those prepared by vacuum thermal reduction.Based on the above research,The?-MoO₃/rGO composites are prepared by hydrothermal method and melt cold extraction method respectively,and the effects of preparation methods on the structure and capacitance properties of?-MoO₃/rGO composites are investigated.The study shows that the specific capacitance(151.17 F g^-1)of?-MoO₃/rGO-2 prepared by melt cold extraction method is larger than that(112.63 F g^-1)of?-MoO₃/rGO-1 prepared by hydrothermal method,its charge transfer resistance is?0.32??smaller than that prepared by hydrothermal method?0.8??,and after 1000 cycles,its cycle retention rate?92.9%?is higher than that prepared by hydrothermal method?90.4%?.By comparing the capacitance properties of single?-MoO₃ and?-MoO₃/rGO composites,it is found that?-MoO₃ and rGO are combined to increase the cycle retention of single?-MoO₃?after 1000 cycles,cycle retention rate is 87.5%?and reduce the charge transfer resistance?1.6??.?5?The?-MoO₃/PANI composite is successfully prepared by in-situ polymerization of?-MoO₃ with PANI.When ammonium molybdate is used as the molybdenum source and the PANI content is 30%,the prepared?-MoO₃/PANI composite had the best electrochemical performance,and its specific capacity is 281 F g^-1,which is higher than that of single?-MoO₃(163.56 F g^-1).After 1000 cycles,the?-MoO₃/PANI composite has a cycle retention of90%,which is superior to a single material??-MoO₃ is 85%,PANI is 85%?.The combination of?-MoO₃ and PANI improves the cycle life of single material and reduces the charge transfer resistance of single material.