Study On Potassium Storage Properties Of Organic 2,5 Benzoquinone-1,4 Potassium Salt And Its Derivatives

The global energy crisis and the renewable energy consumption are becoming more and more serious.The energy storage development and application of clean energy has become an influential science and technology in the world economy.In many new clean energy storage technologies,lithium-ion batteries with the advantages of small size and light weight have been widely used in people’s lives and high-tech products,But only relying on lithium resources will seriously affect the development of large-scale energy storage system in China.Compared with lithium resources,potassium metal is abundant and has similar physical and chemical reaction properties with lithium metal,which is expected to become a new type of secondary battery.However,the large radius of potassium ion requires that the electrode material be able to provide the space to accommodate the large radius ion,and Compared with the critical dependence of the non-polar material on the lattice,the electrode electrode material can be de-intercalated by van der Waals force interaction.At present,the organic anode materials developed for potassium ion batteries have the problems of low first cycle Coulomb efficiency,poor conductivity and low theoretical specific capacity.To overcome the problems of low Coulomb efficiency,poor conductivity and low theoretical specific capacity of organic anode materials for potassium ion batteries.Based on the energy storage mechanism of embedded reaction,this paper designed an organic small molecule 2,5 benzoquinone-1,4 potassium salt material,and modified the material and studied its derivatives.The specific tasks are as follows:(1)Organic small molecule 2,5 benzoquinone-1,4 potassium salt was prepared by simple acid-base reaction and study its electrochemical properties as electrode materials for potassium ion batteries.It’s found that the material has excellent redox peaks in the voltage 1-2 V interval,ion batteries.It’s found that the material has excellent redox peaks in the voltage 1-2 V interval,the material can reversibly store potassium.The reversible discharge specific capacity of the K2BQ material is 180 mAh g-1 at 20 mA g-1 current densities.Due to the formation of SEI film on the surface of negative electrode material,this work improved the Coulomb efficiency in the first week of organic negative electrode material of potassium ion battery by optimizing the electrolyte,this material can reach 96%.on the other hand,Study the energy storage mechanism shows that the energy storage mechanism of this material is the opening and recovery of conjugated hydroxyl groups.(2)Taking into account the poor conductivity of the organic electrode material and the capacity decay at a high rate of 2,5 benzoquinone-1,4 potassium salt,we used in situ recombination method to compound 2,5 benzoquinone-1,4 di-potassium salt with graphene,increasing the conductivity and improves the electron transport rate of the material.The K2BQ/graphene-10 composite has the best electrochemical performance,the reversible discharge specific capacity of K2BQ/graphene-10 composites is 248 mAh g-1 at 20 mA g-1 current density,which is close to the theoretical specific capacity.Further study,the reversible capacity reaches 220,171,110 mAh g-1 at current density of 100,200,400 mA g-1,When the current density returns to 20 mA g-1,the specific capacity can still be restored to about 230 mAh g-1.Afterwards variable speed CV test of the K2BQ/graphene-10 electrode material found that the potassium ion diffusion ability of the K2BQ/graphene-10 composite is better than the K2BQ material,which further illustrates the conductive network formed by the graphene lamellar structure and promotes the electron migration diffusion,thus improving the electronic conductivity of the material.(3)To solve the problem of low theoretical specific capacity of organic negative electrode materials for potassium ion batteries,this experiment used two basic materials:2,2’-bipyridine5,5’-dimethyl acid and potassium hydroxide to synthesize a new type of organic electrode material—2,2’-bipyridine-5,5’-potassium dimethyl.The synthetic purity of the material and its electrochemical behavior as electrode material of potassium ion battery in two electrolyte systems were investigated.Compared with the organic small molecules,this kind of material increases the active site of potassium ion deintercalation,increases the discharge specific capacity of the organic anode material of potassium ion battery,and is expected to become an excellent organic electrode material of secondary battery.