Study On Doping And Electrochemical Performance Of Nickel Oxide And Mesoporous Carbon

In view of the characteristics of nickel oxide?NiO?with high theoretical specific capacity,easy low temperature preparation and mesoporous activated carbon?MAC?with developed pore structure.In this paper,nickel-metal doped NiO complex?Ni@NiO?,Ni@NiO-MAC complex,and sulfur-doped MAC?S-MAC?were prepared.Through SEM?EDS?XRD?BET and electrochemical performance testing methods.The morphology,structure and electrochemical properties of Ni@NiO,Ni@NiO-MAC complex and S-MAC were studied.The main research contents of this article are as follows:?1?Firstly,Ni@NiO and NiO materials were prepared by low temperature pyrolysis in air atmosphere using C₄H₆O₄Ni·4H₂O and Ni?NO₃?₂·6H₂O as raw materials.XRD shows the presence of metallic nickel in Ni@NiO materials.SEM shows that Ni@NiO material is made up of smaller nanoparticles.The analysis of experimental results shows that the addition of metallic Ni improves the conductivity of NiO materials and makes Ni@NiO materials have more excellent lithium storage properties.When the voltage is 0³ V and the current is 0.1 A·g^-1,the first charge ratio of Ni@NiO materials The capacity is as high as 827.7 mAh·g^-1,and the first time Coulomb efficiency is 77.1%,which is much higher than the first Coulomb efficiency of NiO materials.The Ni@NiO material has a specific charge capacity of 773 mAh·g^-1for the first time under a current density of 0.6 A·g^-1,and a specific charge capacity of310 mAh·g^-1 after 30 cycles,with a capacity retention rate of 40.1%.The first and 30th charge specific capacities of NiO materials are only 466.3 and 137.4 mAh·g^-1,and the capacity retention rate is 29.5%.?2?Secondly,although the Ni@NiO material has a higher first charge and discharge specific capacity and good rate performance,the cycle performance is poor.MAC materials have developed pore structures and can support Ni@NiO particles.In this paper,MAC is used to adsorb nickel acetate solution,and after drying,the Ni@NiO-MAC composite is prepared by low temperature pyrolysis under air atmosphere.The SEM results indicate that the Ni@NiO nanocrystals in the Ni@NiO-MAC complex are attached to the MAC particles.Electrochemical performance tests show that the specific capacity of Ni@NiO-MAC composites is higher than that of Ni@NiO materials under different current densities.After 300charge-discharge cycles,the reversible capacity of the Ni@NiO-MAC composite was144.7 mAh·g^-1.Compared with Ni@NiO material,Ni@NiO-MAC composite has better rate performance and cycle performance.?3?Finally,in this paper,the MAC material is modified by sulfur doping,Na₂SO₄is used as the activator,and the sulfur doped MAC?S-MAC?is prepared by high temperature activation treatment.SEM test analysis shows that the particle size of S-MAC material is smaller than MAC.XRD test analysis confirmed that the S-MAC material is amorphous carbon.EDS test analysis shows that the S and C elements in the S-MAC material are evenly distributed.BET analysis shows that the specific surface area(2218 m²·g^-1)of S-MAC material is larger than that of MAC material(1774 m²·g^-1).S-MAC materials show higher reversible specific capacity and cycle performance through electrochemical performance tests.The first reversible specific capacity of S-MAC material is as high as 1197.2 mAh·g^-1,which is much higher than the reversible specific capacity of MAC(698.6 mAh·g^-1).After 300 charging cycles,the chargeable capacity is 955.6 mAh·g^-1,and the capacity retention rate is 72.3%.The results show that the high temperature activation modification of Na₂SO₄ not only makes the MAC material have a better pore structure,but also the S atom doping creates more lithium storage active sites and significantly improves the lithium storage capacity.