In-situ Synthesis And Electrochemical Properties Of Tin Oxide-based Anode Nanomaterials For Lithium Storage

Since lithium-ion batteries are increasingly applied in mobile electronic equipment terminals,new energy electric vehicles,etc.,the performance requirements for lithium-ion batteries have also increased.Compared with the conventional anode carbon-based materials for commercial lithium-ion batteries,the tin-based material owns a theoretical specific capacity of 3 times or more about carbon-based materials,but its volume effect in the charge-discharge process limits its practical application.Therefore,the improvement of the above-mentioned problems by composite modification of tin-based materials and construction of specific nanostructures is of great significance for its application in lithium-ion batteries.This paper focuses on the composite modification of tin dioxide-based nanomaterials with various carbon materials and the study of the controllable construction of its structural morphology.Moreover,the in-depth electrochemical lithium storage performance of tin oxide-based nanocomposites,which used in lithium ion battery as anode materials,has also been researched.The main achievements and innovations are listed on below:(1)A unique SnO2 nanorods binding with reduced oxide graphene low-dimensional structure was first synthesized via in-situ hydrothermal method for the first time.The SnO2 nanorods growing along with[001]crystal plane,the average size of per nanorod is around 250-400 nm,the initial discharge capacity(1761.3 mAh g-1)and reversible capacity(1101 mAh g-1 after 50 cycles)at a current density of 200 MA g-1.This work highlights that by synthesizing unique nanorod structural morphology,the pathways length of ion was shortened and the interface impedance can be reduced,responding to the first ultrahigh discharge/charge capacity(1761.3 mAh g-1/1233.1 mAh g-1)and CE(70%).In addition,with combination of graphene,the ion and electron transmission are largely improved referring to the superior cycle capacity and stable rate ability.(2)A novel composite of ultrasmall SnO2 quantum dots with an average particle size of 4-5 nm anchored on nitrogen-doped reduced graphene oxide(SnO2/NRGO)was first in situ synthesized by the means of hydrothermal method.As an anode material for LIBs,SnO2/NRGO exhibits a much enhanced electrochemical performance,in its initial discharge capacity(1678.4 mAh g-1)and reversible capacity(1333.5 mAh g-1 after 450 cycles)at a current density of 500 mA g-1,which is one of highest capacity after prolonged cycling ever reported and even close to the theoretical capacity of 1494 mAh g'1.It can be seen that the experimentally compounded functionalized graphene with nitrogen element can effectively promote the lithium storage performance of SnO2 electrode material.(3)A convenient in-situ hydrothermal method has been developed firstly to synthesize a novel composite(SnO2/CN-G)that has not been found before by dispersing SnO2 nanoparticles on 3D cheese-like bi-support nanosheets composed of porous g-C3N4 and conductive graphene.The combining of g-C3N4 and graphene could restrain the agglomeration of SnO2 nanoparticles,enhance electronic conductivity of the active materials,and eventually result in enhanced cycling performance(1508.6 mAh g-1 at 200 mA g-1).Furthermore,the large surface area of g-C3N4 and graphene as well as the nanosize of as-synthesized nanomaterials might reduce the initial coulombic efficiency.