The Study On The Design And Preparation Of The Stannous Sulfide-based Composites For Lithium-ion And Sodium-ion Batteries

The rapid growth of storage systems for lithium-ion and sodium-ion batteries（LIBs and SIBs）has encouraged numerous efforts toward the development of the electrode material with better storage properties.Exploring novel and appreciable storage property anode materials for application in both lithium-ion and sodium-ion batteries is being regarded as one of the major parts of the next-generation high-performance storage system.Benefiting from the high capacity and abundant resources,stannous sulfide（SnS）stands out as one of the promising anode materials for the application.However,the inherent inferior electronic conductivity,severe volume changes,and sluggish ion diffusion kinetics of SnS impede its further development and application in lithium-ion and sodium-ion batteries.Herein,to address the issues,based on the strategy of compound strengthening and the component/structural design,the strategies related to the carbon-coated as well as the multiple systems could be employed to construct corresponding SnS-based composite.From the carbon-coated to the introduction of the multicomponent system with carbon matrix to the multicomponent system with the heterostructure as well as structural optimization,the conductivity and the reaction kinetic of SnS can be reinforced through the enhancements of the coating structure,storage active site,synergistic effect,and heterostructure,which could improve the storage property of SnS for LIBs and SIBs effectively.The main thesis researches are as follows:（1）The PDA coating route are used to synthesize carbon-coated SnS composite.The nanoscale carbon layer of theSnS@C composite could be detected by the characterization results.The nanoscale carbon layer can not only enhance the conductivity and dispersion of SnS,but also improve the electric/ion transfer.Besides,the carbon-coated structure can relieve the internal stress caused by the volume expansion,which could reinforce the stability of the electrode.With the comparison of SnS,theSnS@C anode exhibits preferable storage properties.TheSnS@C anode shows the discharge specific capacity of 670 m Ah g^-1 at 0.1 A g^-1 after 120 cycles for LIBs.As for SIBs,theSnS@C anode exhibits the capacity of 246 m Ah g^-1 at 100 cycles.（2）SnS decorated zeolitic imidazolate framework-8 derived ZnS/3D porous carbon composite（ZnS/PC）using the vacuum quartz capsule-assisted decoration method（ZnS/SnS/PC）.Different from the conventional physical deposition（vaporization–conversion–condensation strategy）,ZnS/SnS/PC heterogeneous composite could avoid the crystalline surface of the metal sulfides（SnS）,and theSnS could be confined into the pore surface of ZnS/PC to form theSnS decorated pluralistic composite.Decoration of carbonaceous composite with SnS can provide extra redox reactions,which exhibit apparent enhancement of the lithium storage properties.The mesopores and micropores are coexistent within the ZnS/SnS/PC,which not only introduces adsorption sites,but also facilitates the transport of electric/ion.Besides,the appreciable robustness and conductivity of the carbon matrix could promote the high storage property of bimetallic sulfides.Furthermore,the synergistic effect between different components gives a considerable influence on cycle stability.The ZnS/SnS/C anode shows the capacity of 867,686,629,and 512 m Ah g^-1 at0.1,0.3,0.5,and 1 A g^-1 respectively for LIBs.Meanwhile,the capacity of102 m Ah g^-1 at 2 A g^-1 for SIBs after 200 cycles.（3）The carbon-coated SnS-Fe_1-xS heterostructure cell（SFS@SC）has been constructed through the coprecipitation route,the carbonized and in-situ vulcanized conversion of SnS-Fe_1-xS could be realized through carbonization and sulfidation processes,and theSnS-Fe_1-xS Janus heterostructure unit can be obtained.Different from the common previously reported bimetallic sulfides heterostructure for electrode materials,the SFS@SC composite exhibit a heterogeneous distribution for theSnS and Fe_1-xS rather than uniform distribution,resembling the double-faced god Janus.Coupling of high conductive Fe_1-xS with SnS to construct bimetallic sulfides heterostructure,which provides abundant reaction platform for the composite.Besides,the internal electric field cold rapid charge transport,which could relieve the sluggishness of theSnS.The different reaction potentials between Fe_1-xS and SnS could avoid the stress concentration,which could decrease the volume variation rate.S-doping carbon layer could not only restrain the volume expansion,but also maintain the stability of the heterostructure unite as well as the synergistic effect.For LIBs,the SFS@SC anode could maintain the capacity of 586.9m Ah g^-1 after 500 cycles at 2 A g^-1.And the anode exhibits 310 m Ah g^-1discharge capacity after 3000 cycles at 2 A g^-1 for SIBs.（4）The electrospinning-assisted coated method was used to synthesize organic fiber embedded ZnSn（OH）₆precursor.And the carbon-coated SnS-ZnS heterostructure composite（SZS@C）could be constructed by the following carbonization and sulfidation processes.The carbon layer derived from the organic fiber could construct a stable coating morphology.The carbon layer can play the part in a conductive network,a stable coated structure for volume variation of bimetallic sulfides,while the bimetallic sulfides can fully deliver the merit of high capacity and internal electric field.Compared with SnS and ZnS anodes,the SZS@C anode can exhibit preferable storage properties as well as reaction kinetics.The SZS@C anode can exhibit the capacity of 1060 m Ah g^-1 after 120 cycles at 0.1 A g^-1 for LIBs.As for SIBs,the capacity of 480 m Ah g^-1 cold be maintained after 100 cycles at 0.1 A g^-1.