Design Of Advanced Electrode Materials For Applications In Potassium/Sodium Ion Batteries

The fast increase of the electric vehicles and renewable energy markets has stimulated the pursuit of energy storage devices.Meanwhile,the increasing scarcity of lithium resources on earth limits the large-scale application of lithium-ion batteries.Therefore,the development of potassium/sodium ion batteries with abundant resources is in line with the need of the progress of the current era.We synthesized Bi_0.4Sb_1.6Te₃ nanoparticles with a small amount of layered graphene composite(Bi_0.4Sb_1.6Te₃/graphene)by a simple hydrothermal process and applied the composite to the anode of potassium ion battery.The material exhibits satisfactory electrochemical performance due to the unique composition and structural advantages of the material:1)the presence of alloy-type components,2)the unique high-dynamic laminated crystal structure,and 3)the sandwich structure(which improves electrical conductivity and achieves spatial constraints).The high discharge specific capacity of 378 mAh g^-1 can be achieved at the current density of 0.1A g^-1 for 100 cycles,and the capacity can still be maintained at 128 mAh g^-1 after 500 cycles at 1 A g^-1.This work can not only provide a new avenue for the study of electrode materials for potassium ion batteries,but also demonstrates the great potential of polymetallic chalcogenides for energy storage applications.A kind of polyimide derivative(PMAQ)was prepared from pyromellitic dianhydride and2,6-diaminoanthraquinone by simple polycondensation reaction,and applied to the cathode of sodium ion battery.This material not only shows excellent mechanical strength,good structural stability and extended?conjugated system,but also has the inherent high theoretical capacity of conjugated carbonyl polymer and fast redox reaction kinetics.It achieves high specific capacities of 141 mAh g^-1 after 500 cycles at 500 mA g^-1 and 71 mAh g^-1 after 500 cycles at 10A g^-1.Furthermore,the PMAQ also exhibits good electrochemical performance in the application of the all-organic battery,which can maintain 57 mAh g^-1 discharge capacity for100 cycles at 0.5 A g^-1,and exhibits good cycling stability and rate capability.This work demonstrates the potential application of organic materials containing multiple oxidation active units in the next generation of electrochemical energy storage devices.With the continuous expansion of the application range of electrochemical energy storage devices,it has become an urgent problem to find a suitable battery system with high energy density in energy storage system.In this thesis,the anode materials for potassium ion battery and cathode materials for sodium ion battery not only highlight the application potential of the two kinds of materials in energy storage,but also provide a new idea for the development of the next generation of sustainable energy storage system.