Synthesis And Investigation Of Anode Materials For Carbon-based Potassium-ion Batteries

Potassium-ion batteries（KIBs）,owing to abundant reserves,wide distribution and low cost of potassium,and similar physicochemical to lithium,are regarded as a promising candidate to lithium-ion batteries（LIBs）in the large scale energy storage fields.However,the radius of K⁺（1.38?）is larger than that of Li⁺（0.76?）,leading to the sluggish kinetic process of potassiation in conventional graphite anode material due to the short layer distance,which results in lower capability.Exploiting the novel anode materials is the key to the long-term development of KIBs.Porous carbon materials are recognized as promising candidate substitute of graphite for KIBs because of their controllable porous structure,high surface area,and high electrochemical activity.In this work,we synthesize two types of porous and nitrogen doped carbon materials,and investigated their electrochemical performance in KIBs as anode.The main research works could be described as below:（1）Pore structure controllable UIO-66-NH₂-derived nitrogen-doped mesoporous carbon,was synthesized by a double-solvent diffusion-pyrolysis method（DSDPM）.Through the methode of DSDPM,the derived carbon material not only inherite the morphology of the UIO-66-NH₂ precursor,but also exhibit a high surface area and abundant pore structure.When used as anode material of KIBs,N-PC exhibits excellent cycling stability and rate performance.N-PC could deliver a reversible capacity of 346 m Ah g^–1 at a current density of100 m A g^–1.Even if at 2 A g^-1,it still obtained specific capacity of 214 m Ah g^–1.N-PC shows the optimal potassium storage capacity resulting from the creation of pores and introduction of defect sites.What’s more,the kinetic analysis proves that the battery’s high K storage performance is dominated by a surface-driven capacitive behavior,and corresponding capacitance contribution ratio reaches 80%.N-PC sample has the fast ion diffusion rate of（2）Used Na Cl crystallization as template,we prepared 3D nitrogen-doped porous carbon by high temperature pyrolysis of Zn-containing precursor zinc phthalocyanine and non-Zn-containing precursor phthalocyanine.During the pyrolysis process,the loss of pyridinic-N for Zn-containing precursor is smaller than the non-Zn counterpart.Besides,.It exhibits optimal electrochemical performance owing to pyridinic-N which is beneficial to the potassium storage ability of carbon materials.Experiments with using different amount of Na Cl demonstrated that 10 m L of Na Cl was the optimal for the best charging/discharging capacity.It delivers the reversible capacity of 326 m Ah g^-1 at 100 m A g^-1,and 312 m Ah g^-1even after 100 cycles.Even though at a current density of 500 m A g^–1,it could exhibit a stable capacity of 192 m Ah g^-1 after 1000 cycles.