具有类混凝土结构的SiOx-C锂离子电池复合材料的制备.pdf
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1、采用一种简单的方法制备具有类钢筋混凝土结构的SiOC负极材料,其中碳纳米管(carbon nanotubes,CNTs)如同钢筋一般嵌入材料中以提供应力支撑,硅原子被原子级分散的碳和氧原子均匀包裹,最后通过化学气相沉积镀上最外层的碳层,进一步抑制材料的体积变化。基于此独特的结构设计制备的CNTs/SiOxC/C负极表现出优异的电化学性能,其在0.5 Ag-1的电流密度下循环970圈后容量保留率为80%。关键词:SiOx;碳纳米管;碳层包覆;负极;锂离子电池中图分类号:TB33文献标识码:A文章编号:10014861(2023)09176609DOI:10.11862/CJIC.2023.144
2、Preparation of SiOxC composite materials with a reinforcedconcretelike structure for lithiumion batteriesMA JinYangXU YaNanZHANG YuDU HongBin(State Key Laboratory of Coordination Chemistry,School of Chemistry and Chemical Engineering,Nanjing University,Nanjing 210093,China)Abstract:This work reports
3、 a simple method to prepare a SiOC anode material with a reinforced concretelikestructure,in which carbon nanotubes(CNTs)were embedded and acted like steel bars to provide stress support,andthe silicon atoms were wrapped with atomically dispersed carbon and oxygen concrete matrix.An outermost carbon
4、layer was plated via chemical vapor deposition to further inhibit the volume change of the material.Thanks to theunique structural design,the prepared CNTs/SiOxC/C anode showed excellent electrochemical performance with ahighcapacity retention rate of 80%after 970 cycles at 0.5 Ag-1.Keywords:SiOx;ca
5、rbon nanotube;carbon coating;anode;lithiumion battery0IntroductionGraphite is the mainstream anode material for lithiumion batteries(LIBs),but it is slowly failing to meetthe needs of highperformance LIBs due to its low theoretical capacity(372 mAhg-1).Although siliconbasedmaterials have a high theo
6、retical capacity,their hugevolume expansion(ca.300%)in the process of chargeand discharge greatly reduces the cycling performanceand hinders its marketization process12.In comparison,silicon oxide(SiOx,0 x2)had attracted wideattention because of its higher theoretical capacity thangraphite and small
7、er volume expansion than elementalsilicon,which is a promising anode material for thenext generation of LIBs34.To alleviate the volume expansion of Si basedmaterials,researchers have developed several solutions,such as coating siliconbased nanomaterials withcarbon or oxides(such as SiO25,TiO26),or p
8、reparation第9期of siliconbased nanomaterials with specific morphology.For example,Li et al.coated SiOxnanoparticleswith carbon formed by asphalt pyrolysis7.Yang et al.constructed amorphous TiO2shells by a facile solgelapproach to adapt to the volume change of silicon based material8.Li et al.introduce
9、d silicon basedmaterials onto carbon nanotubes by chemical vapordeposition(CVD)using silane gas as a silicon source9.Sun et al.prepared ultrathin SiOxnanosheets by solvothermal stripping of CaSi210.Furthermore,researchersalso found that coated Sibased materials in atomic sizewere a better choice com
10、pared to conventional nanosized coating.For instance,Zhou et al.prepared atomically homogeneous SiOx/C hollow spheres by a onepotaldimine condensation for LIB anodes,realizing therequirements of atomiclevel coating and special morphology of materials at the same time11.Herein,we report the preparati
11、on of a compositeSiOC material(named CNTs/SiOxC/C)with a reinforced concretelike structure,in which carbon nanotubes(CNTs)are embedded in the material like steelbars to provide stress support inside the material.Atomically dispersed carbon and oxygen atoms encasethe silicon atoms as a buffer matrix.
12、A carbon protection layer was further coated onto the outer layer of thematerial by CVD to fully mitigate the expansion effectof the material.As a result,the prepared compositematerial delivered stable cycle performance with acapacity retention rate of 80%after 970 cycles at a current density of 0.5
13、 Ag-1.1Experimental1.1MaterialMultiwalled CNTs were acquired from XianfengNano Co.,Ltd.3Aminopropyltriethoxysilane(C9H23NO3Si,APTES,98%)was purchased from Bide Co.,Ltd.Ammonium hydroxide(NHHO)was purchased fromSinopharm Chemical Reagent Co.,Ltd.Dichloromethane(CH2Cl2)was purchased from Sinopharm Che
14、micalReagent Co.Ltd.,and was dried over CaH2before use.1.2Fabrication of CNTs/SiOxC and CNTs/SiOxC/CIn a typical procedure,100 mg of CNTs were firstdispersed in 15 mL of CH2Cl2.2 mL of NHHO wasadded into the above solution and stirred for 10 minutes.Then,2 mL of APTES was added dropwise.Afterstirrin
15、g at room temperature overnight,the solution wasleft to stand and stratified rapidly.The solid wasobtained by centrifugation,which was then put intotube finance and heated at 900 for 2 h with a ramping rate of 5 min-1under Ar atmosphere to obtainCNTs/SiOxC.To coat CNTs/SiOxC with carbon,theproduct C
16、NTs/SiOxC was further heated under a toluene atmosphere at 800 for 2 h.For comparison,reference materials named CNTs/SiOxC800 and CNTs/SiOxC1000 were prepared following the same procedure as CNTs/SiOxC,but pyrolysis temperature set at 800 and 1 000,respectively.ReferencematerialsnamedCNTs/SiOxC2.5an
17、dCNTs/SiOxC1.5 were prepared following the same procedure as CNTs/SiOxC,but the dosage of APTES was2.5 and 1.5 mL,respectively.1.3Material characterizationsThe powder Xray diffraction(PXRD)patterns ofthe prepared materials were recorded on a Bruker D8Xray diffractometer(Cu K radiation,=0.154 18 nm,2
18、=1080,operated at 40 kV and 40 mA).Scanningelectron microscope(SEM,Hitachi S4800 electronmicroscope,20 kV)and transmission electron microscope(TEM,JEM 2100 microscope,200 kV)wereused to investigate the morphologies of all materials.X ray photoelectron spectroscopy(XPS,PHI 5000VVersaProbe spectromete
19、r)was used to investigate thesurface composition of the materials.The Raman spectra of the materials were obtained on a LabRAMAramis Raman spectrometer(Horiba,488 nm laser).The thermogravimetric analysis(TGA)was performedon a Netzche STA449F3 from 30 to 960 under flowing air with a heating rate of 1
20、0 min-1.1.4Electrochemical characterizationsThe working electrode was composed of activematerial(Mass fraction:70%),sodium alginate(Massfraction:20%),super P(Mass fraction:10%),and copper foil as a current collector,and lithium sheets wereused as counter electrodes.The load mass of the activemateria
21、l of all electrodes was about 0.81.2 mgcm-2马晋杨等:具有类混凝土结构的SiOxC锂离子电池复合材料的制备1767无机化学学报第39卷after drying at 80 for 500 min under vacuum.Thecoin cells(CR2032type)were assembled in an argonfilled glovebox(H2O,O2contents were below 10-7cm3cm-3).Celgard 2400 membrane was used as a separator.1 molL-1LiPF6in
22、ethylene carbonate/dimethylcarbonate/diethyl carbonate(EC/DMC/DEC,1 1 1 involume)was used as an electrolyte.Galvanostatic charge discharge(GCD)measurements were carried out on a Neware battery testingdevice(Shenzhen,China)with a voltage window of0.012 V(vs Li/Li+).Cyclic voltammetry(CV)with avoltage
23、 window of 0.012 V(vs Li/Li+)and a scan rateof 0.1 mVs-1.Electrochemical impedance spectroscopy(EIS)with a frequency range from 0.01 Hz to 100kHz was conducted on an electrochemical station(CHI650D,Shanghai Chenhua Instruments Inc.,China).2Results and discussionFig.1 shows the preparation process fo
24、r the material studied in this work.The commercial CNTs wereused as hard templates,which were coated by inorganic and organic hybrid network structures with the atomic distribution of Si,C,and O elements through hydrolysis reaction of APTES under alkaline conditions.After calcination in inert atmosp
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