Controllable Preparation Of Porous Carbon Materials And Study Of Potassium Negative Electrode Performanc

To alleviate the energy crisis and make use of renewable energy,large-scale energy storage systems have been widely concerned.The demand for lithium-ion batteries（LIBs）is growing rapidly,and it is urgent to develop a new low-cost energy storage device.Potassium ion batteries（PIBs）are considered a promising substitute for LIBs because they have similar storage mechanisms.Carbonaceous materials are expected to become the main commercial anode materials of PIBs.Hard carbon is a typical amorphous carbon with a large specific surface area.However,slow dynamics and large volume expansion limit its development.To solve the above problems,different types of porous carbons and carbon dots were prepared to increase the number of active sites and improve the slow kinetics of potassium storage.The main research contents are as follows:1.Phenolic resin was prepared by hydrothermal method.In the process of preparing phenolic resin,a high block polymer template was added to prepare nano phenolic resin balls,and then porous nano carbon balls（PCN）were obtained by nitrogen annealing.The PCN electrode can provide the specific capacity of potassium ion discharge of 376 m Ah g^-1,and the reversible capacity of 249 m Ah g^-1 can still be maintained after 1000 cycles at a current density of 1 A g^-1,and the coulombic efficiency is close to 100%.2.Flexible,self-supporting,and large-sized waste paper towel-derived carbon nanobelts（HCPPC）were prepared by a simple one-step solid-state pyrolysis method using waste paper towel-derived carbon as the precursor.The HCPPC electrode can provide the specific capacity of potassium ion discharge of 204.2 m Ah g^-1,and the reversible capacity of 155.19 m Ah g^-1 can still be maintained after 400 cycles at a current density of 1 A g^-1,and the coulombic efficiency is close to 100%.3.Using glucose as a carbon source,the carbon point was confined in waste graphite（CDs@Gra）by the one-step carbonization method,and CDs with uniform size and high dispersibility were obtained in waste graphite（Gra）.The quantum size of CDs can reduce the ion diffusion length and provide a continuous transmission channel so that CDs@Gra can provide high potassium storage capacity.The specific capacity of potassium ion discharge of CDs@Gra electrode can be 207.7 m Ah g^-1 after being filled with potassium battery as negative electrode material,and the reversible capacity of155.8 m Ah g^-1 can still be maintained after 1000 cycles at a current density of 1A g^-1,and the coulombic efficiency of the first cycle is 96.32%.