Research On Electrochemical Energy Storage Batteries Based On Transition Metal Oxide (Sulfide) Anode Materials

With the advancement of the energy transition and the proposal of dual-carbon goals,clean energy has gradually become the main body of the energy structure.Energy storage has become a major technical support for the acceptance of new energy.Among them,electrochemical energy storage has developed rapidly.As the most promising anode materials for electrochemical energy storage batteries,transition metal oxide(sulfide)has high specific capacity,but they have problems such as low intrinsic conductivity and volume expansion during ion deintercalation,which seriously affect the battery's long cycle stability and rate characteristics.In response to these problems,this thesis has investigated the modification of anode materials design and the integrated design of battery structure for transition metal oxide(sulfide)energy storage batteries.First,in terms of the anode materials,the cycle and rate performance of the battery is improved by several methods such as morphology and structure design,composite with carbon materials,composite with materials,and introduction of defects:(1)By chemical vapor deposition,nickel oxide and carbon nanotubes can be recombined in situ,oxygen vacancy defects are introduced as the oxygen is removed,so that the volume expansion of NiO is limited while the conductivity is improved;(2)Through Li-GO-EDA solution control method,transition metal oxide(sulfide)and graphene oxide were compounded and defects were controlled at the same time The capacity retention rate of lithium ion battery is close to 90%after 200 cycles;(3)The two materials of molybdenum oxide and molybdenum sulfide are combined in situ to form a spherical core-shell structure by hydrothermal method.Lithium-ion battery has higher capacity(0.5 C second circle 1090 mAh/g)and better rate performance(509 mAh/g at 10 C rate);(4)A series of spheroidal TiO2(B)materials with vacancy defects were prepared by hydrothermal and calcination,the sodium ion battery is cycled 500 times at a rate of 5 C,and the specific capacity remains at 67 mAh/g.By calculation,the pseudo-capacitance contribution value of the battery capacity can reach 59.87%at a scanning speed of 0.4 mV/s.At the same time,the battery exhibits a better rate performance than P25 in the low temperature environment of 0?,-30?,and-50?.Next,in terms of the battery structure,the transition metal oxide(sulfide)are loaded on the side of the glass fiber diaphragm by spin coating to realize a new type of lithium-ion battery structure of integration of anode and separator.The mesh pore structure of the glass fiber separator limits the volume expansion of the materials while shortening the ion diffusion distance,improving the dispersibility and reactivity of the materials.Scanning electron microscopy can clearly observe the layered structure of the separator,and the material is evenly dispersed on one side of the diaphragm.This structural design improves the cycle stability and rate performance of the molybdenum sulfide-based lithium-ion battery,and the capacity retention rate of the forty cycles reaches more than 88%;it also improves the cycle reversible capacity of the molybdenum oxide-based lithium-ion battery,at 10 C high rate,it is close to 900 mAh/g.Calculations show that the pseudo-capacitance contribution rate of the integrated battery reaches 43.59%,which is about twice that of the ordinary battery.