Study On Preparation And Electrochemical Performance Of NiSiO/RGO Composites

At present,lithium-ion batteries have become the main energy source for large-scale energy storage equipment due to their high energy density,long cycle life and good safety performance.In recent years,with the in-depth study of anode materials,it has been found that the transition metal layered silicate materials have the advantages of wide raw material sources,low cost,high safety,environmental friendliness and high theoretical specific capacity,which have the potential to become excellent lithium-ion batteries electrode material.As a new material in the transition metal layered silicate materials,layered nickel silicate?Ni₃Si₂O₅?OH?₄,referred to as NiSiO?has attracted wide attention due to its unique layered structure and high first specific capacity.However,when used as anode electrode materials for lithium-ion batteries,relatively poor electrical conductivity of NiSiO is still an important factor restricting its further development.Studies have shown that the preparation of high electronic conductivity composite materials is an effective means to improve poor electronic conductivity.It is worth noting that the two-dimensional carbon nanomaterial graphene has applications in different fields due to high electrical conductivity,large specific surface area(2600 m² g^-1)and stable structure etc.In general,graphene is also often used as conductive additive for cathode and anode materials.Based on this,a series of core-shell layered nickel silicate/reduced graphene oxide?referred to as NiSiO/RGO?composite materials were prepared to improve the electrical conductivity of NiSiO,and explored their electrochemical performance as a negative electrode material for lithium ion batteries,and the following innovative results were mainly achieved:?1?Using silicon dioxide?SiO₂?nanospheres as templates,NiSiO/RGO composites were prepared by in situ generation of NiSiO on the surface of graphene oxide?GO?by hydrothermal method.The microscopic morphology of the materials shows that the layered NiSiO/RGO composite materials and the NiSiO nanospheres formed in situ on the surface of SiO₂ form a physical mixture.This structure not only inherits the high first-time specific capacity of NiSiO,but also has the excellent electronic conductivity of GO.As anode material for lithium-ion batteries,the NiSiO/RGO composite material with GO mass concentration of 1 mg/m L exhibits more excellent electrochemical performance due to the unique layered structure and the excellent characteristics of graphene itself.At a current density of 0.1 A g^-1,after100 cycles,the discharge capacity stabilized from 1653.9 m A h g^-1 in the first cycle to710.9 m A h g^-1,which is about twice the theoretical capacity(372 m A h g^-1)of commercial graphite.When the current density is restored from 1.6 A g^-1 to 0.1 A g^-1,the reversible specific capacity can be restored from 443.2 m A h g^-1 to 719.3 m A h g^-1,which indicates that the material still has stable structure and excellent electrochemical reversible performance after charge and discharge cycles with different current densities.Therefore,it can be seen that the NiSiO/RGO composite materials with GO mass concentration of 1 mg/m L is high-performance lithium ion battery anode materials with practical prospects.?2?The layered structure of NiSiO provides fast ion transfer channel.The introduced GO improves the transfer ability of ions and electrons.The multi-OH structure of the binder HA increases the reactive sites for lithium ion adsorption.The synergistic effect of the above structure makes the active material?NiSiO/RGO composite material with GO mass concentration of 1 mg/m L?:acetylene black:binder?HA/H₂O system?=80:10:10 assembled electrode materials show better rate performance than other similar materials.At a high current density of 1.6 A g^-1,its discharge specific capacity is as high as 505.7 m A h g^-1.It can be seen that HA has a good application prospect as a binder for lithium ion batteries.