Preparation Of Potassium Titanate Anode Material And Research On Its Energy Storage Performance

The continuous update of energy technology requires the vigorous development of new electrochemical energy storage systems.The development of LIBs has been restricted by cost and safety issues.PIBs and SIBs have attracted widespread attention due to resource abundance and environmental friendliness.In order to develop high energy density battery energy storage System,seeking suitable electrode materials is imminent.Due to the low cost of the preparation process and no harm to the environment,the potassium titanate material is expected to become one of the popular negative electrode materials for potassium ion batteries.This thesis uses tetrabutyl titanate as the titanium source and potassium methoxide as the potassium source.Potassium titanate materials with different crystal phase structures are synthesized by hydrothermal method combined with high temperature solid phase method.After a series of characterization methods,the preparation process is studied.The influence law of the crystal phase structure,morphology and electrochemical properties of potassium titanate materials provides a data basis for the research and development of high-performance potassium titanate electrode materials.Potassium titanate samples were prepared by P123/F127 assisted hydrothermal method.The samples synthesized at different hydrothermal temperatures are K2Ti6O13 with a tunnel structure,which is in the shape of a coiled wedge-shaped nanosheet.When the hydrothermal temperature rises from 160℃ to 220℃,the degree of curl of the nanosheets decreases and the aspect ratio increases.Potassium titanate samples hydrothermally synthesized at 160℃ have the highest electrochemical performance due to the morphology of cluster-curled nanosheets and the largest specific surface area.When applied to PIBs and SIBs,they have the highest electrochemical performance at 20 mA g-1.The specific charging capacity is 82.4 mAh g-1 and 97.5 mAh g-1 respectively.Potassium titanate with different crystal structure was prepared by hydrothermal method combined with high temperature calcination method.After characterization and analysis,with the increase of the calcination temperature,the crystal phase transition occurred at 500℃～700℃,the sample changed from the tunnel structure to the layered structure,and the K2Ti8O17 calcined below 500℃ into the tunnel structure,showing nanometer flake-shaped,calcined at 700℃ or higher into layered K2Ti409,showing nano-rod shape.From 300℃ to 900℃,the specific surface area and pore volume of the sample decrease.Potassium titanate with different crystal structures shows different energy storage performance.The potassium titanate sample calcined at 300℃ has the best electrochemical performance,showing a potassium storage capacity of 103.1 mAh g-1 at 20 mA g-1 and the sodium storage capacity of 112.1 mAh g-1.The potassium titanate samples were prepared by the sol-gel method combined with the high-temperature calcination method,and the effects of different potassium titanate content and calcination temperature on the potassium titanate samples were explored.As the potassium content increases,the sample becomes smoother and the diameter becomes smaller.As the calcination temperature increases,the microscopic size of the material continues to increase.It has been found that the sample calcined at 900℃ with K/Ti=0.5 has the best crystallinity.It is layered K2Ti4O9,showing a tetragonal nanorod morphology,and has the best electrochemical performance.At 20 mA g-1,showing a potassium storage capacity of 58.4 mAh g-1 and a sodium storage capacity of 115.2 mAh g-1.