Study On Preparation Of Germanium Disulfide-based Composite And Its Sodium Storage Properties

Due to its rich reserves of sodium,sodium ions batteries（SIBs）have attracted extensive attention.Meanwhile,the physicochemical property and working principle of SIBs are similar to lithium ions batteries,thus it is considered as an effective supplement for lithium ions batteries.However,the radius of sodium ion（1.02（?））is larger than that of lithium ion（0.76（?））,thus many materilas with high lithium storage cannot provide satisfied storage capacity in SIBs.Therefore,the development of new high-performance anode materials is a key problem for SIBs.In this paper,the conversion-alloying reaction type GeS₂material with high theoretical specific capacity is selected as the research object.In order to improve the cycling performance and rate capacity,the various GeS₂-based composites have been modified by structural design and composite phase preparation.The specific research contents are as follows:（1）The GeS₂/r GO composite（GeS₂/3DG）was prepared by the method of self-assembly and high temperature roasting,in which the GeS₂ nanoparticles and r GO were connected by Ge-C bond.The three-dimensional porous structure not only acts as a conductive network,but also provides a buffer space for the volume change.Meanwhile,the existence of C-Ge bond is beneficial to the electron/ion migration,which improves the reaction kinetics.The GeS₂/3DG composite shows excellent cycling stability and rate performance when tested at a voltage window of0.01-3.0 V.The reversible specific capacity of GeS₂/3DG can reach 370m Ah g^-1 after 800 cycles at 2 A g^-1.（2）Using Ge-MOF coated resorcinol formaldehyde resin as raw material,the GS-OM sample with the coexistence of orthonormal and monoclinic GeS₂ was synthesized by precise control of sintering temperature.The GS-OM heterostructure has strong electron interaction at the heterogeneous interface,which is beneficial to enhance the electron transfer rate and improve the reaction kinetics.Additionally,the composite phase structure also improves the stability of the material.The GS-OM composite can deliver a reversible specific charge capacity of669 m Ah g^-1 after 600 cycles at 10 A g^-1,showing excellent rate and cycle performance.（3）The GeS₂/GeO₂/Zn S/r GO polymetallic phase composite（GGZ/C）was constructed by introducing Zn S and GeO₂ materials,which is distributed evenly on the graphene network.The Zn S and GeO₂ as the frame structure improve the cyclic stability of GeS₂,while graphene as the conductive network to accelerate the electron migration rate.The results of electrochemical testing show that the reversible charging capacity of GGZ/C composite is 621 m Ah g^-1 with the capacity retention of 98%at 0.5 A g^-1 after 100 cycles.Under high rate of 5.0 A g^-1,the specific capacity of GGZ/C is 519 m Ah g^-1 after 650 cycles,and the capacity retention rate is 91%,realizing the unification of high capacity,large rate and long cycling.