Preparation Of The Sb-based Composites And Their Application In Lithium-ion Batteries

Due to the higher energy and power density,lower self-discharge rate and environment-friendly,lithium-ion batteries(LIBs)have been developed rapidly and applied widely in field of electric vehicle and portable electronic products,etc.Graphite is the most excellent anode material for currently commercial LIBs.However,because of the lower theoretical capacity,it can not satisfy the ever-increased demand of application.Antimony(Sb)is considered as an alternative anode material with great promise because of its high theoretical specific capacity of 660 mAh g-1.Nevertheless,the practical application of the Sb anode material is seriously hampered by its gigantic volume change which results in electrode pulverization and rapid capacity fading.To overcome this problem,in this paper,the TiO2,RGO,MOFs,etc.are introduced to enhance the cycling performance of the Sb anode material.By using simple preparation methods like reducing,replacement reaction and electrophoretic deposition,a series of Sb-based materials are facilely fabricated and their composition,morphology and electrochemical performance are studied.And the obtained related research results are as follows:(1)Peapod-like Sb@TiO2 composite is fabricated by a simple low-temperature oxidation and followed by a reduction route.The deoxidization process of the Sb2O3 precursor can leave significant free space between the Sb particle and the TiO2 shell,which can buffer the volume expansion of the Sb core.These voids and the supporting effect of the TiO2 shell can make a key function to enhance the electrochemical performance.When used as an anode material for LIBs,the peapod-like Sb@TiO2 composite exhibits a reversible capacity of 450.2 mAh g-1 after 100 cycles at a current density of 100 mA g-1.Furthermore,even at a higher current density of 2000 mA g-1,this composite can also deliver a discharge capacity of 340.2 mAh g-1 Such outstanding electrochemical performance could be attributed to synergistic effect between the Sb core and the TiO2 shell,as well as the space between them.(2)The integrated Sb/RGO thin film composite is in situ fabricated onto the Ni foam by replacement reaction and electrophoretic deposition method.This integral Sb/RGO thin film electrode is three-dimensional and porous,binder-free and free of conductive agent.Furthermore,in this Sb/RGO thin film,the Sb thin film is fabricated between the inner Ni foam and outer RGO,formation a sandwich-like structure.Used as an anode material for LIBs,the sandwich-like Sb/RGO thin film delivers an initial discharge capacity of 872.9 mAh g-1 and a reversible discharge capacity of 424.1 mAh g-1 after 50 repeated cycles when measured at a current density of 100 mA g-1.This good electrochemical performance could be attributed to the sandwich-like structure,and the supporting and buffer effect of the RGO.(3)A porous Sb/C composite is obtained by a replacement reaction method employing the ZIF-67 as a template.In this composite,the ultrasmall Sb nanoparticles with an average size of 15 nm are homogeneously encapsulated into the carbon matrixes,forming a hierarchical porous structure with nanosized building blocks.Used as an anode material for LIBs,this composite exhibits high lithium storage capacities,excellent rate capability and superior cycle stability,higher than many reported results.Notably,a discharge capacity of 565 mAh g-1 at a current density of 200 mAg-1 is delivered after 100 repeated cycles.Even at a high current density of 1000 mA g-1,a discharge capacity of 400.5 mAh g-1 is also maintained after 500 cycles.Such superior lithium storage performance of the designed Sb/C composite can be attributed to the synergistic effect between Sb nanoparticles and the porous carbon matrixes.(4)Based on the highly active Sn,a series of morphology/component-controllable Sn-Sb micro/nano-structures are fabricated by a one-pot replacement reaction technique employing metallic Sn as both template and reducing agent.Typical Sn-Sb structures,hollow,dendritic or their mixed type,are successfully fabricated.As anode materials for lithium-ion batteries,the hollow or dendritic Sn-Sb materials exhibit higher discharge capacities,cycling performance and rate discharge property.Especially,for the Sn-Sb hollow spheres,a reversible capacity of 751 mAh g-1 are achieved after 100 cycles at a current density of 100 mA g-1.Meanwhile,the hollow Sn-Sb structure delivers a specific capacity of 451.3 mA h g-1 at 500 mA g-1 after 150 cycles when used for sodium ion batteries.The superior electrochemical performance that are higher than many reported results can be attributed to the special morphology and structure,which can shorten the transportation distance of lithium/sodium ion and provide extra free space to buffer the volume expansion during the lithium/sodium insertion/extraction.