| Antimony-based anode materials have received extensive attention in the research of lithium/sodium/potassium ion batteries due to their excellent chemical stability,low reduction potential,and high theoretical capacity.The current research work shows that hysteresis kinetics and volume expansion are the main factors that limit electrochemical performance.To overcome these shortcomings and achieve performance improvements,researchers have adopted the strategies of nanostructure design,morphological structure control,and composite with carbon materials.Under the implementation of these strategies,the electrochemical performance of antimony-based anode materials in lithium-ion batteries(LIBs)has been significantly improved.However,the performance of sodium-ion batteries(SIBs)and potassium-ion batteries(KIBs)is still lower than that of LIBs.It means that the strategies for enhancing the performance of SIBs and KIBs anodes still need to be further improved.Besides,the currently reported antimony-based anode materials just can be applied to two battery systems(such as LIBs and SIBs,SIBs and KIBs)at the same time.If an antimony-based anode material applied in all three battery systems can be explored,it is great significance for the development of antimony-based anode materials.Sb2O4 with the highest theoretical capacity shows great potential in secondary ion battery research among kinds of Sb-based anode materials.However,the current performance improvement strategies mainly focus on nanostructure design and carbon composite materials construction.There are almost no research reports on performance improvement through crystal structure design.In addition to common oxides,Sb2Se3 as antimony-based chalcogenides representation can also be candidates for excellent anode materials in secondary ion batteries due to their highly reversible electrochemical reaction mechanism.However,the current performance of Sb2Se3/C composites as SIBs and KIBs anode materials is unsatisfactory.Therefore,in order to obtain excellent Sb2Se3 anode materials,the Sb2Se3/C composite structure still needs to be further improved.In addition,there are relatively few studies on Sb-based intermetallic compounds in secondary ion batteries.Based on the above research status,this dissertation focuses on the crystal structure design of Sb2O4,the optimization of Sb2Se3/C composite structure,and Co and Sb intermetallic compounds' construction to improve electrochemical performance.The research work carried out around this goal has mainly obtained the following results:(1)The Sb2O4 nanowire assembly mesocrystal structured micro-flower material was successfully constructed by a gentle hydrothermal method.Owing to the ordered orientation and few grain boundaries of mesocrystal structure,the prepared Sb2O4 microflower elelctrode exhibits fast e-transfer during the alloying/dealloying process.This excellent reaction kinetics improves the utilization of active materials in the high current charging and discharging process.The mesocrystal Sb2O4 microflower exhibits high capacity and enhanced rate performance in SIBs half-cells(5 A g-1,432 mA h g-1),and high energy(226 Wh kg-1)and power density(1700 W kg-1)in full cells.This result provides understanding of the electrochemical behavior of the mesogenic structure and offers important ideas for improving the electrochemical performance of alloy anode materials through crystal structure design.(2)A series of amorphous shell/crystalline core Sb2O4 nanowires assembled microflower material was fabricated by controlling the crystallization process.Analysis results show that the surface amorphous structure exhibits faster reaction kinetics between the electrode and the electrolyte interface than the crystal structure,which is of great significance for the subsequent bulk diffusion and deep active material reaction.The crystal structure can provide inside fast e-and Na+migration channels,and enhance the stability of the amorphous shell/crystal core structure.The final results show that the sample with a thinner amorphous layer and suitable crystallinity shows the most excellent sodium storage performance with high energy density(179.4 Wh kg-1)and power density(1581 W kg-1).This excellent performance is mainly due to the synergy effect of the surface amorphous and higher crystallinity of the composite structure.Under this effect,the sample shows the fastest Na+bulk diffusion rate and stable electrode structure,guaranteeing the deep reaction of active material.This result can provide understanding for the performance optimization process by amorphous-crystalline composite structure design.(3)Taking the amorphous shell/crystalline core Sb2O4 nanowires assembled microflower structure with thick amorphous layer as raw material,constructing the partial amorphous-crystalline network structure through solid-phase reaction.This structure retains the excellent interface reaction from surface amorphous structure and improves the electrode charge mobility and Na+ diffusion rate by bridging the amorphous network through the crystal,eventually realizing rate performance improvement.It shows high capacity of 294.4 mA h g-1 at 10 A g-1 in SIBs,and maintains capacity of 187.8 mA h g-1 under 1 A g-1 in KIBs.This result can provide ideas for the research that optimizing amorphous-crystalline composite structure to improve rate performance.(4)Carbon capsule confined Sb2Se3 composite material was fabricated by solvothermal combined with solid-phase methods.This material can remain intact structure during repeated Na1insertion/extraction processes,exhibiting significantly enhanced structural stability.This stable electrode structure can maintain a fast and stable Na+extraction path,good electrochemical contact and stable SEI film.Finally,this structure achieves rapid Na+extraction during the alloying reaction process with excellent sodium storage performance.It still maintains a reversible capacity of 380 mA h g-1 at a current density of 2 A g-1 after 600 cycles.This result can provide idea for design and analysis for the research on improving the performance of alloy anode materials by compounding with carbon.(5)Inducing isolated carbon capsule confined rod-like Sb2Se3 structure gradually transform to continuous carbon confined Sb2Se3 nanoparticle composite material was achieved by adjusting the polarity of the solvent.This continuous carbon confined structure with good structure stability can remain intact during repeated K+insertion/extraction processes,effectively reducing the formation of extra SEI film and optimizing path of K+/e-.The continuous carbon confined structure realizes a stable cycle performance up to 1000 times,and maintains high reversible capacity of 410 mA h g-1 with a capacity attenuation of 0.122 mA h g-1 per cycle.In full cell,it also exhibits high energy density of 181.4 Wh kg-1.This result can provide ideas and a basis for the current research on the preparation of durable high-capacity alloy-based KIBs anode materials.(6)Novel CoSb2O6 nanodot material was prepared by a gental hydrothermal method.Owing to the retarined volume expansion and short K+diffusion path caused by the nanostructure,this anode material exhibits excellent cycle and rate performance.It can maintain a high capacity of 368.9 mA h g-1 after 500 cycles at 0.1 A g-1 with capacity loss only 0.406 mA h g-1 per cycle.Furthermore,the CoSb2O6 nanodots were used as raw materials.After being coated with carbon,it was used to prepare CoSb/Sb2O3/N-C composite structure with a stable interface during in-situ confinement reduction process at high temperatures.The N-doped carbon and the stable interface of CoSb/Sb2O3 promote the surface reaction of active materials,presenting a pseudocapacitance controlled electrochemical reaction mechanism.Under this mechanism,the CoSb/Sb2O3/N-C composite structure shows excellent electrochemical performance in LIBs,SIBs and KIBs.This result can promote the research of general high-performance Sb-based anode materials and provide a basis for the preparation of such anode materials. |
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