Construction Of One-dimensional Porous Carbon And Their Potassium-ion Storage Performance

Potassium ion batteries（KIBs）have become one of the powerful candidates for constructing a big-scale energy storage with the merits of their inexhaustible potassium reserves.Carbon materials possess the merits of low cost,wide sources,and undisturbed physicochemical performances,undoubtedly have become the first choice for the application of anodes for KIBs.However,the narrow interlayer spacing of graphite leads to slow dynamics of large-size K⁺during the potassiation and depotassiation process,resulting in the poor rate performance.And the structural collapse result from the huge volume expansion generally occur in the potassium storage process,which accelerates the fade of capacity.Therefore,obtaining high-capacity and high-rate non-graphitic carbon with large interlayer spacing is considered to be one of the options for overcoming the disadvantages of graphitic carbon.Aiming at the problems of low specific capacity of KIBs and other problems,this paper designs carbonaceous structures from the perspective of structural design,and obtains anode materials with excellent performance for KIBs.The details are as follows:No.1 Sea urchin is one of the oldest echinoderms in the ocean.Its cell membrane has an osmotic effect on high-concentration sodium/potassium seawater and a porous spinous structure similar to the siphon effect of a hydraulic pump can quickly complete the processing of seawater and food.Herein,inspired by the structure of sea urchins and their ability to absorb and transport K⁺,we developed a nitrogen-doped sea urchin structure porous carbon（N-SPC）with enhanced dynamics and porous siphon effect,and successfully applied it to advanced KIBs.The biomimetic N-SPC possess high specific surface area（SSA）,hierarchical micropores/mesopores,moderate N-doped defect sites,exhibiting suitable K⁺diffusion barrier energy,hence contributing to outstanding cyclability(296 m Ah·g^-1 at 1 A·g^-1 after 2000 cycles)and rate performance(116 m Ah·g^-1 at 20 A·g^-1)for KIBs.Density functional theory（DFT）theoretical calculations further confirmed that the enhanced potassium storage performance of the N-SPC benefits from a large number of N-doped active sites and the rapid reaction kinetics brought about by the optimized N-doping.More impressively,the full battery assembled with the Prussian blue cathode shows a high discharge specific capacity of 288 m Ah·g^-1 at 0.2 A·g^-1 after 50 cycles,and 113 m Ah·g^-1 after 100 cycles at 0.47 A·g^-1.In this work,the reasonable structure of sea-urchin-structured carbon has guided the development of KIBs to more rapid development and application.Finally,we extended it to the sodium ion battery system and got good results.No.2 Inspired by capillary action,we reasonably selected biomass catkins with a one-dimensional hollow tube as the research object,and chemically treated them to control different porosities.When carbon materials with different porosities are applied to the anode of KIBs,the improvement of a large number of micropores leads to an escalation in the SSA,which boosts the wettability of the electrolyte,thereby remarkably enhancing the cyclability and rate performance of the KIBs.This strategy confirms that rich porosity has an active impression on the improvement of the electrochemical behavior of KIBs.