Preparation Of Carbon Materials Derived From Gelatin For Electrochemical Energy Storage

Among various electrochemical energy storage devices,Li-ion batteries(LIBs)and electrochemical capacitors have received much attention owning to their merits.Electrode materials are the key parameter that is important in determining their performance.Carbon-based materials have been widely investigated for use as the electrode materials of the aforementioned energy storage devices because of their low cost,high chemical stability,and non-toxicity.What’s more,the biomass-derived carbon materials have attracted much attention owning to their advantages of abundance,environmental concern,and economic value.In this thesis,high-performance activated carbons and nitrogen-doped graphene-like nanosheets have been fabricated from gelatin,aiming at improving the low specific capacity of commercial activated carbon and graphite.The main research contents and results are summarized as followed:1)A 3D honeycomb-like porous gelatin was prepared from commercial one,and subsequently used as the precursor to prepare the high-performance activated carbon through carbonization followed by KOH activation.The sample Gel-700 prepared through 600 ℃ carbonization and 700 ℃ activation delivered high specific capacitances of 357 F·g-1 and 227 F·g-1 at current densities of 1 A·g-1 and 100 A·g-1.In addition,after 7500 charge/discharge cycles at a current density of 10 A·g-1,it showed 93.0%retention of the initial capacitance,demonstrating excellent cycling stability.Moreover,a symmetric supercapacitor was assembled,which delivered an energy density of 10.3,9.7,and 8.2 Wh·kg-1 at power densities of 250,2500,and 25000 W·kg-1,respectively.Furthermore,a capacity retention as high as 97.6%was achieved after 10000 cycles at 10 A·g-1 using this symmetric supercapacitor.These findings have demonstrated that the activated carbon prepared from honeycomb-like porous gelatin has great potential for application in high-performance supercapacitors.2)Nitrogen-doped graphene-like nanosheets(NGN)were prepared by co-pyrolysis of gelatin and melamine via one-step high temperature solid-phase reacton,in which gelatin was used as the carbon source,and melamine was utilized as both the nitrogen precursor and the reactive template.The NGN had a superior lithium-storage performance,showing a promising anode material.The sample NGN-800 annealed at 800℃ afforded an initial reversible capacity of 1181 mAh·g-1 at 100 mA·g-1 and an excellent cycling stability of 1360 mAh·g-1 after 140 charge/discharge cycles.In addition,the NGN-800 also delivered high specific capacitances of 518 mAh·g-1 and 200 mAh·g-1 at current densities of 1 A·g-1 and 5 Ac·g-1,respectively,demonstrating an excellent rate capability.This method is simple,economical,and environmentally friendly.