The Preparation And Lithium Storage Performances Of One-dimensional Potassium Niobate Nanomaterials

In this paper,the three one-dimensional potassium niobate nanomaterials of KNb₃O₈,K5.75 Nb10.85 O30 and K₂Nb₆O₁₆ were first synthesized by electrospinning,and their lithium storage performances were explored for the first time.This article is divided into five chapters.In Chapter 1,the research background and research significance of this paper were pointed out briefly,and the features,applications,and the main preparation methods of nanometer materials especially one-dimensional nanomaterials were introduced as key points.Finally,the thesis topic was summarized.In Chapter 2,the KNb₃O₈ nanorods with serious aggregation were synthesized via electrospinning followed by annealing and prepared by using niobium oxalate,oxalic acid and potassium acetate as the main raw material.The KNb₃O₈ was a non-stable quadrilateral structure and had two niobium ions.The research results showed that the KNb₃O₈ nanomaterials had certain lithium storage properties with poor performance.In the cycle performance test,the charge specific capacity of the 1st cycle of the KNb₃O₈ nanorods was156.5 mAh g-1,and the charge specific capacity of the 50 th cycle was 65.6 mAh g-1.The charge capacity retention rate of the previous 50 cycles was only 41.9 %.In Chapter 3,the dispersive K5.75 Nb10.85 O30 nanorods were synthesized via electrospinning followed by annealing and prepared by using niobium oxalate,oxalic acid and potassium acetate as the main raw material.The K_5.75Nb_10.85O₃₀ was a non-stable quadrilateral structure and had only one niobium ions.As the electrode materials for lithium ion batteries,K_5.75Nb_10.85O₃₀ nanorods had good rate performance and cycle performance.In the rate performance test,the charge capacities of sample in the 1st,11 th,21th,31 th,41th cycles were153.2,107.4,81.7,64.7,113.7 mAh g-1 respectively.In cycle performance test of K_5.75Nb_10.85O₃₀,the charge capacity decreased rapidly before the first 15 cycles and after stabilized.From the 15 th cycle to the 90 th cycle,the average loss rate per cycle of K5.75 Nb10.85O30 nanorods was only 0.2%.In Chapter 4,the K₂Nb₆O₁₆ nanorods were synthesized via electrospinning followed by annealing and prepared by using niobium oxalate,oxalic acid and potassium acetate as the main raw material.The K₂Nb₆O₁₆ was a stable pentagon structure and had only one niobium ions.The researc results showed that the K₂Nb₆O₁₆ nano material had excellent rateperformance and cycle performance.In the rate performance test,the charge capacities of K₂Nb₆O₁₆ in the 1st,11 th,21th,31 th,41th cycles were 94.3,80.5,61.1,43.6,88.7 mAh g-1respectively.In the cycle performance test,the charge specific capacity of the 1st cycle of the K₂Nb₆O₁₆ nanorods was 94.8 mAh g-1,and the charge specific capacity of the 50 th cycle was65.7 mAh g-1.From the 1st cycle to the 90 th cycle,the average loss rate per cycle of K5.75Nb10.85 O30 nanorods was only 0.8 %.In Chapter 5,the work in this paper were summarized simply,and the possible developments of the subject were prospected.