Preparation And Study Of Novel Potassium Ion Battery

Lithium-ion batteries(LIBs)are the most advanced portable electronic products and electric vehicles on the market.They are one of the most promising large-scale energy storage applications in the 21 st century.However,due to the lack of global lithium resources,lithium-ion batteries are costly.It is imperative to develop new energy storage systems with low cost,high performance and long cycle life.As a substitute for lithium-ion batteries,potassium-ion batteries have received attention in recent years.Most of the work is on the study of positive and negative materials for potassium ion batteries,and no potassium ion full battery with excellent electrochemical performance has been prepared.In this paper,a new type of multi-ion potassium-ion battery was designed.The lithium-potassium hybridization and potassium-type dual-ion battery were combined to conduct in-depth research and discussion.The electrolyte formulation was optimized to prepare a new type of potassium ion with excellent electrochemical performance.The battery conducts in-depth characterization analysis of the reaction principle and mechanism of the battery.Preparation and properties of Li+/K+ hybrid ion batteries with different hybridization ratios.Firstly,the electrolyte of K+/Li+ hybrid ion battery was optimized.Several kinds of electrolytes were compared for the electrochemistry of K+/Li+ hybrid ion battery(mainly with 20% and 30% lithium content).Performance,the optimal electrolyte ratio was selected as EC:EMC:DMC:PC=2:2:1:1.Then,different batteries with different hybridization ratios were prepared for charge and discharge performance and electrochemical impedance test.When the lithium content is 20%,the battery has high specific capacity,cycle stability and coulombic efficiency.At this time,the impedance is low and the electrochemical is low.The reaction activation energy is also low.Combining electrochemical impedance,electrochemical activation energy,and cycle performance testing,and considering the reduction of lithium resource consumption,we chose a hybrid ion battery with a lithium content of 20% as the optimal hybridization ratio.The performance of the rate performance test,the reaction mechanism analysis and the electrochemical performance improvement mechanism of the hybrid ion battery with a lithium content of 20% were investigated.Electrochemical performance: The discharge specific capacity can reach 86.3 m Ah g-1 when charging and discharging at 25 C rate;after 500 cycles of 5 C rate,the discharge specific capacity is as high as 104.6 m Ah g-1,and the capacity retention rate is 99%.According to the anode XRD and XPS tests,the alloying products were analyzed as Li2Sn5 and K2Sn5,and the standard PDF diffraction pattern and crystal structure of K2Sn5 were calculated by MS.The ex-in situ XRD,Raman test of the cathode and anode materials at different voltages,and the in-situ stress test of the negative electrode materials show that the battery has good material structure stability and reactant phase reversibility.The diffusion energy barrier of potassium and lithium in the tin lattice is simulated.The diffusion energy barrier of Li is much smaller than K.Therefore,the introduction of Li+ can greatly reduce the reaction activation energy of the battery,increase the diffusion coefficient of K+,and generate lithium and tin.The Li2Sn5 phase and the K2Sn5 phase formed by potassium and tin have obvious metal characteristics,which are beneficial to electron transport and greatly improve battery rate performance and reversible capacity.