Controable Synthesis And Lithium Storage Properties Of Transition Metal Phosphides

Lithium-ion batteries?LIBs?are widely used in hybrid vehicles and portable electronic devices,make great changes in modern social life for the excellent anvantages,for example,high energy density,long cycle life,high safety,pollution-free and memoryless.However,their performance is still far from meeting the rapid development of science and technology.The demand for LIBs with good stability and high capacity in the society is increasing and needs to further improve the eletrochemical performance.Now,conventional graphite is widely used as anode material in commercial LIBs.However,there are still some shortcomings such as poor rate performance,low theoretical capacity,overcharge prone lithium dendrites.Transition metal phosphides,due to its large lithium storage capacity,long cycle life,low polarization,green and other advantages,have been attracted worldwide attention.This paper use hydrothermal/solid phase to synthesis different morphologies of cobalt phosphide,nickel phosphide,study the elelctrochemical properties.In addition,we also used functional carbon materials?graphene and carbon nanotubes?decorate the as-prepared TMPs and enhance the electrochemical properties.The following research results:1.In this work,a rational design of multiwalled carbon nanotubes?MCNTs?modified porous CoP/carbon composite?CoP/C@MCNTs?using metal-organic framework?MOF?as precursor.The tests of electrochemical performance show that,the as-prepared CoP/C@MCNTs composite exhibits promising lithium storage performance with a reversible capacity of 547.5 mAh/g at a current density of 500 mA/g after 200 cycles,while CoP/C could only maintain 190.7 mAh/g in the same conditions.2.Ni₂P/GO was synthesized by a low temperature phosphating reaction using Ni?HCO₃?₂/GO composite as precursor.We research the electrochemical performance of Ni₂P/GO as negative electrode material of lithium battery.Ni₂P/GO composite can keep a capacity of 356.75 mAh/g after 100 cycles while pristine Ni₂P remain only 266.6 mAh/g.It indicates that graphene could improves the electrochemical behavior of the material.3.We use metal-organic framework-Ni?MOF-Ni?templates to prepare N-doped carbon coating Ni₂P porous spheres?Ni₂P/NC?with core-shell structure as electrode material for lithium-ion batteries and supercapacitors.The results show that the Ni₂P/NC composites possess good cycle stability and rate performance owing to its regular carbon-coated porous spheres.After 200 cycles,at a current density of 0.5 A/g,the reversible specific capacity can still maintain 479.8 mAh/g.