Preparation,mechanism Analysis And Electrochemical Application Of Sugar Carbon Materials

In recent years,more and more attention has been paid to developing renewable carbon resources to prepare porous carbon.In terms of sustainability,sugar will be used more and more as carbon precursor to prepare carbon in the future.In this paper,sugar carbon was prepared by using sugar as carbon precursor and polyacrylamide gel as skeleton.After that,porous carbon was prepared by high-temperature activation and low-temperature activation respectively and used as anode material for lithium ion battery.Its electrochemical application was analyzed.(1)Four soluble sugars were used as carbon precursor,including two monosaccharides(glucose and fructose)and two disaccharides(maltose and sucrose).Polyacrylamide hydrogel was used as three-dimensional skeleton.After carbonization at high temperature,the dense and non-porous carbon blocks was formed.Through the analysis by ~1H NMR spectroscopy,it was found that there was no chemical reaction between the two raw materials,but physical bonds existed.Hydrogen bonds acted as sacrificial bonds in inhibiting the expansion caused by the thermal treatment process.The thermogravimetric analysis of sugar-PAM and the Fourier infrared analysis of the sample in different carbonization temperature were carried out to study the reaction and change of functional groups in thermal treatment.Then,the morphology and structure of the samples treated by carbonization at 1200? were characterized and found that the carbon retention rate of the four samples was found to be about 90% after calculation.(2)The porous carbon were prepared through by KOH activation in 800?.The effect of different glucose concentration on electrochemical properties and specific surface area,pore diameter of porous carbon materials was studied and the influence of eventually found different density of carbon caused by different concentration of sugar in after activation treatment leads to different specific surface area and pore volume.The result show that sugar content and specific surface area and pore volume is not a linear relationship,when the glucose concentration is 0.1 g/ml,compared with other sugar concentration,the porous carbon have the better electrochemical properties.The specific capacity of the first discharge and the first charge respectively is 1962 m Ah/g and 468 m Ah/g.(3)The porous carbon was prepared by the reaction of KOH with sugar and activated in low temperature environment.Sugar-pam hydrogel was prepared.After drying,it was bloated with KOH solution,and then pre-carbonized and activated at low temperature,followed by carbonized porous Sugar carbon materials at high temperature.TGA and FTIR tests showed that only the first three of the four sugars could be activated at low temperature.KOH could not only react with sugars to generate hydrogen to generate stomata,but also KOH could break the hydrogen bond network of the gel to prevent stomatal healing during heat treatment.The porous carbon prepared by low temperature activation was found to account for more than 80% of the total pore volume by nitrogen desorption test.The results show that the porous carbon prepared by glucose as carbon precursor has relatively good electrochemical performance as the cathode of lithium ion battery.Then the influence of low temperature activation of KOH at different concentrations on carbon structure and electrochemical performance was investigated.The results showed that the porous carbon with low temperature activation of 800 g/L KOH had relatively good electrochemical performance.