| Along with the development and progress of the society,demand of people for energy is getting bigger and bigger,the demand for environmental friendly energy resources is also rising at the same time.In this case,a large number of renewable energy resources have appeared,such as wind energy,solar energy,tidal power,etc.,when we use these energies,it will make no harm on the environment,has become a powerful replacement for fossil fuels.However,As the energy being used,how to store them has became a new hot topic.As a new type of electrochemical energy storage device,zinc ion hybrid supercapacitor has attracted more and more attention in recent years.As a kind of hybrid supercapacitor,it organically integrates capacitor cathode and battery zinc anode.Therefore,in addition to the electrostatic absorption and desorption energy storage mechanism of the traditional electrochemical double-layer capacitor,it also integrates the energy storage mechanism of Faraday pseudocapacitor,making its energy density greatly improved compared with that of the traditional supercapacitor and overcoming the shortcomings of the low power density of the battery at the same time.In addition,the electrochemical performance of electrochemical energy storage devices is mainly determined by the electrode materials,which makes the design and preparation of new carbon electrode materials to improve the electrochemical performance of zinc ion hybrid supercapacitors has become one of the current research hotspots.In this work,we have synthesized porous carbon nanosheets with specific microstructure and use them as cathode of zinc ion hybrid supercapacitor to obtain zinc ion hybrid capacitor with more excellent electrochemical performance.The specific results are shown in the following steps:(1)With sodium polyacrylate as carbon source,combined with the template and the etching effects of potassium bicarbonate,we have made a formation of layered porous carbon nano lamellar structure.Because of its unique surface morphology and microstructure characteristics can provide plenty of activity points for ions during the electrochemical reactions,but can also promoted the transfer and transmission of ions,which showed excellent electrochemical performance.The results show that the in-situ sodium carbonate can be used as a template to form nanocages,and the nanocages are further fractured under the etching reaction of potassium bicarbonate to form the nanosheet structure.The results show that this is a kind of zinc ion hybrid cathode material with excellent electrochemical performance,for example,at a low current density of 0.5 A/g,the maximum specific capacity reaches 177.7 m A·h/g,while at a current density of 20 A/g,it can still maintain the specific capacity of 85.5 m A·h/g,with A retention rate of nearly 50 %.In addition,it also shows good cycle stability(90 %capacity retention after 10000 cycles at 10 A/g current density).Moreover,it still has a high energy density(68.4 Wh/kg)at a high power density(15390 W/kg).(2)with starch as the precursor,by the auxiliary of potassium nitrate and potassium hydroxide activation method,the obtained porous carbon nanostructure,studies have shown that potassium nitrate is a kind of morphology control reagent in the preparation of nanometer and play a crucial role in the process of product morphology is closely related to the amount of adding potassium nitrate and potassium hydroxide used chemical activation improve porosity.The electrochemical energy storage device assembled as cathode material of zinc ion hybrid supercapacitor can obtain a high specific capacity of 149 m A·h/g at a low current density of 0.2 A/g,and a specific capacity of 75 m A·h/g at a current density of 20 A/g,the retention rate is as high as50.3% at the same time.In addition,it exhibits good cycle stability(over 90% specific capacity retention under 10 A/g current density after 10000 cycles)and high energypower density characteristics(119 Wh/kg at a power density of 160 W/kg). |
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