| The reserves of bamboo in nature are very abundant,but its utilization rate is low,especially the bamboo processing residues(such as bamboo powder)produced by bamboo processing are not fully utilized.On the other hand,environmental issues and energy shortages have become a worldwide problem.For this reason,it is necessary to seek clean energy or high-performance energy storage devices to replace the burning of fossil energy.Therefore,in order to achieve high value-added utilization of bamboo and solve the problem of energy shortage,bamboo processing residues can be used to micron or nanometer to construct a high-performance,low-cost,safe and environmentally friendly energy storage device.The paper regulates the size of bamboo fibers by adjusting the grinding distance and homogenization treatment,the internal pore structure of carbon aerogels by adjusting the carbonization temperature,and the chemical composition and graphitization degree of carbon aerogels by introducing nitrogen atom doping.The effects of fiber size control and carbonization conditions on bamboo-based carbon aerogels were systematically studied,and the mechanism of nitrogen and other heteroatom doping modification on the energy storage performance of carbon aerogels was discussed,and a higher power was obtained.Density and energy density of supercapacitors.The main research contents and results are as follows:(1)Adjust the size of the bamboo fiber by adjusting the distance between the grinding discs of the grinder and the number of homogenization,so as to explore the differences in the electrochemical performance of bamboo fiber carbon aerogels of different sizes.The diameter of the bamboo fiber obtained by adjusting the distance between different grinding discs is in the range of 30-120 nm,20-36.7 nm,13.3-33.3 nm and 10-33.3 nm,respectively,and the diameter of the bamboo fiber after high pressure homogenization is in the range of 6.6-11.7 nm;The smaller the size of the bamboo fiber,the greater the specific capacitance of the electrode material.The carbon aerogel electrode material prepared by the homogenized bamboo fiber is tested by constant current charge and discharge when the current density is 0.5 A g-1The specific capacitance can reach 86 F g-1,and it has a relatively stable cycle stability.After the 5000 cycles of cycle life test,the specific capacitance of the electrode material can still remain 89.3%of the initial specific capacitance.(2)The carbonization temperature is adjusted to control the pore structure of carbon aerogels,so as to explore the influence of carbonization temperature on the electrochemical performance of bamboo fiber carbon aerogels.The carbonization temperature changes the density of the carbon aerogel.As the temperature increases,the density of the carbon aerogel gradually increases,from 5.03 mg cm-3 to 6.61 mg cm-3;with the increase of the carbonization temperature When the carbonization temperature reaches 800℃,the carbon aerogel has the largest specific surface area(38.43 m2 g-1)and mesoporous pore volume(0.0327 cm3 g-1),and when the current density is 0.5 A g-1,the specific capacitance of the electrode material(CBA-800)can reach 69.9 F g-1,and The cycle stability is excellent.After the 5000 cycles of cycle life test the specific capacitance of the electrode material can still be maintained at 89.5%of the initial specific capacitance.After assembling CBA-800 into a water-based supercapacitor,it is found that the device has a higher power density(5.04 kW kg-1)and energy density(1.32 Wh kg-1).(3)The chemical composition,graphitization degree and specific surface area of carbon aerogels are controlled by adjusting the nitrogen doping amount,so as to explore the influence of nitrogen doping amount on the electrochemical performance of bamboo fiber carbon aerogels.Using bamboo nanofiber aerogel as the carbon source and dicyandiamide as the nitrogen source,different nitrogen-doped carbon aerogels can be obtained by adjusting the amount of nitrogen doping.The nitrogen content increases with the increase of nitrogen doping,and the nitrogen content increases from 3.39 wt%to 15.51 wt%.The amount of nitrogen will affect the specific surface area and pore volume of the carbon aerogel.As the nitrogen content increases,the specific surface area of the carbon aerogel first increases and then decreases,and the pore volume decreases accordingly.When the nitrogen content is 10.53 wt%,the nitrogen-doped carbon aerogel(N-CBA7)has the largest specific surface area of 492.28 m2 g-1,and the mesoporous pore volume can reach 0.6782 cm3 g-1,at a current density of 1A g-1,the specific capacitance of N-CBA7 can reach up to 289.63 F g-1,and the cycle stability is excellent.After 10,000 cycles of cycle life test under a large current density of 5 A g-1,the ratio of electrode material The capacitance can be maintained at 82.7%of the initial specific capacitance.The N-CBA7 was assembled into a water-based supercapacitor.After testing,it was found that the device has a higher power density(3.14 kW kg-1)and energy density(3.14 Wh kg-1).In summary,it can be seen that the size of the bamboo fiber has a greater impact on the electrochemical properties of the carbon aerogel.The smaller the fiber size,the larger the specific capacitance of carbon aerogel electrode materials.The carbonization temperature will affect the internal structure of carbon aerogels.The specific surface area of carbon aerogels and mesoporous pore volume first increase and then decrease with the increase of temperature,and the larger the specific surface area of carbon aerogels,the larger the carbon aerogels.Nitrogen doping is an effective means to improve the electrochemical performance of carbon aerogels,and nitrogen content will affect the internal structure and electrochemical performance of nitrogen-doped carbon aerogels.The specific surface area and mesoporous carbon aerogels first increase and then decrease with the increase of nitrogen content,and the specific capacitance of nitrogen doped carbon aerogel electrode materials first increases and then decreases.The nitrogen-doped carbon aerogels electrode material is assembled into a water-based supercapacitor,which has a relatively high power density and energy density.This research provides a theoretical foundation for the preparation of electrode materials for supercapacitors with low cost,adjustable structure and sustainable development,and is an important reference for the development of bio-energy materials. |
PDF Full Text Request