Study On Layered Metal Oxides Of Cathode Materials For Potassium-ion Batteries

With the rapid development of modern technology,clean and renewable energy sources（such as solar energy,wind energy,etc.）are constantly being used by mankind.However,the effective use of these new energy sources still needs to solve many difficult problems.They often have shortcomings such as intermittent and instability,which limit their further development and application.Therefore,it is very important to develop high-efficiency energy storage equipment for regulating the energy output of intermittent solar and wind energy.Potassium ion batteries are an emerging technology in energy storage equipment.The main obstacle to practical application is the lack of suitable cathode materials that can provide high quality/volume energy,When layered metal oxides are used as cathode materials for potassium ion batteries,there are still some challenges.Improve to meet the requirements.This article mainly uses the electrospinning technology to synthesize the layered metal oxide with fibrous structure as the cathode material of the potassium ion battery,adjust the potassium ion content between the material layers to prepare materials with different potassium content between the layers,and analyze and compare the materials with the best performance.The excellent fibrous material has been compared and analyzed comprehensively with the granular material synthesized by the high-temperature solid-phase method.The main work content is as follows:Three materials with expressions of K_0.1Mn_0.7Ni_0.3O₂,K_0.2Mn_0.7Ni_0.3O₂,K_0.4Mn_0.7Ni_0.3O₂were prepared by adjusting the potassium ion content between the material layers.The prepared calcined products with different potassium content all have an ultra-long and continuous structure,showing a good fibrous structure,and the prepared three fibrous materials all have a single crystal structure.The electrode material K_0.2Mn_0.7Ni_0.3O₂ can exhibit a cycle stability of about 60 m Ah·g^-1 and a coulombic efficiency of almost 100%at a current density of 200 m A/g.And the material K_0.2Mn_0.7Ni_0.3O₂also shows excellent rate performance.According to the AC impedance analysis of the test battery and the comparison of potassium ion diffusion coefficient,potassium ion has the highest diffusion rate in the material K_0.2Mn_0.7Ni_0.3O₂,which also corresponds to the good electrochemical performance of K_0.2Mn_0.7Ni_0.3O₂.The particles material K_0.2Mn_0.7Ni_0.3O₂ was synthesized by the high-temperature solid-phase method,and compared with the fibrous K_0.2Mn_0.7Ni_0.3O₂ material prepared by the high-voltage electrostatic spinning method.It can be seen from the constant current charge and discharge cycle test results,The fibrous sample K_0.2Mn_0.7Ni_0.3O₂ can exhibit a cycle stability of maintaining a specific capacity of about 60 m Ah·g^-1 at a current density of200m A/g,which is comparable to the granular sample K_0.2Mn_0.7Ni_0.3O₂ Compared with the capacity of about 30 m Ah·g^-1,the constant current charge and discharge capacity of the fibrous sample is much higher than that of the granular sample.The diffusion rate of potassium ions in the fibrous material K_0.2Mn_0.7Ni_0.3O₂ is also greater than that of the granular material,which corresponds to the better electrochemical performance of the fibrous K_0.2Mn_0.7Ni_0.3O₂.These excellent electrochemical performances can be attributed to the fibrous morphology that makes full use of its larger effective contact area,which has better wettability with the electrolyte during the cycle,which helps to improve the potassium ion in the solid The kinetic conditions of the medium diffusion,thereby greatly improving the electrochemical performance.