| With the rapid development of portable equipment,green energy and electric vehicles,it is indispensable to develop high energy density safe energy storage equipment.Lithium-ion batteries have become one of the first choices for sustainable energy development due to their high voltage,no memory effect,light weight,small size,low maintenance cost,and low self-discharge rate.Nowadays,the synthesis of heterogeneous structures by mixing compounds of different materials to improve the physical and chemical properties of materials is the focus of attention.Bimetal oxides and sulfides have become the current research hotspot due to their higher conductivity and synergistic effect in lithium ion storage.In this paper,Zn-Co bimetallic oxides and sulfides were used as the main research objects,and rice hull cellulose and graphene were used as substrates to successfully prepare ZnO/CoO@RHC,ZnO/CoO@rGO and Zn0.76Co0.24@rGO bimetallic composites by different methods.And perform physical characterization and electrochemical performance tests such as XRD,Raman,XPS,BET.The main research contents and conclusions are as follows:?1?ZnCo2O4 nanoparticles were prepared by solvothermal method using Co?NO3?2·6H2O and Zn?NO3?2·6H2O as raw materials with the aid of urea and ammonia.At the same time,the rice husk was treated with alkali and acid to extract cellulose from the rice husk.The obtained ZnCo2O4 was subjected to a hydrothermal carbonization reaction with a rice husk cellulose precursor to obtain ZnO/CoO@RHC.The influence of calcination temperature on the electrochemical performance and the microstructure and electrochemical performance of ZnCo2O4,ZnO@RHC,CoO@RHC and ZnO/CoO@RHC were investigated.The test results show that the optimal calcination temperature of the bimetallic material ZnO/CoO@RHC is 550?,and it has higher electrochemical activity,conductivity,and synergistic effects between metals than single metal oxides,showing the best electrochemical performance.The specific capacity is stable at 878 mAh g-1 after 100-laps at a current density of 100 mA g-1.?2?Graphite oxide was prepared by modified Hummers method.ZnO/CoO@rGO was successfully prepared by solvothermal reaction using graphite oxide,Co?NO3?2·6H2O,Zn?NO3?2·6H2O as raw materials.The effects of the temperature of the water bath on its structure and electrochemical performance were investigated,and the microstructures and electrochemical performances of the ZnO@rGO,CoO@rGO and ZnO/CoO@rGO synthesized under the same conditions were compared.The test results show that as the temperature of the water bath increases,the agglomeration of the material decreases and the crystallinity increases.ZnO/CoO@rGO obtained at 80?showed the best electrochemical performance.We found that Double Metal Oxides due to the synergy between the two metal elements promote ultrafine distribution of the material,and have higher electrochemical activity and electrical conductivity,exhibiting best electrochemical performance.Demonstrated a specific discharge capacity of 619 mAh g-1 after 100 cycles at a current density of 100 mA g-1?3?A Zn0.76Co0.24S@rGO bimetallic composite was successfully obtained by performing a vulcanization reaction on the basis of ZnO/CoO@rGO.We explored the differences in morphology and electrochemical performance of the Zn0.76Co0.24S@rGO and ZnO/CoO@rGO precursors and the monolithic materials ZnS@rGO and CoS2@rGO.The Zn0.76Co0.24S@rGO bimetallic composite material formed by S replacing O has improved conductivity,flexibility and durability,exhibiting excellent reversibility and cycle stability.It showed 989 mAh g-1 after 100 cycles at a current density of 100 mA g-1. |
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