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*,*,*,*,*,*,寿命寿命硅负采材料,Silicon,anode,with,life,cycle,life,Prof.Xinping Qiu,Department of Chemistry,Tsinghua University,Beijing,100084,China,寿命寿命硅负采材料Silicon anode with l,12/3/2024,Difficulties for silicon anode application,Large volume exchange lead to structural failure of electrode,Relative low conductivity and rate performance,Electron number,Energy density,Molecular mass,Si:4200 m Ah/g,2,Multi electron reaction materials,8/7/2023Difficulties for silic,12/3/2024,J.R.Dahn,Electrochem.Solid-State Lett.,2001,4,A137.,J.R.Dahn,J.Electrochem.Soc.2003,150,A1457.,3,Colossal volume change,Change in(a)length+and width x,(b)height,and(c)volume of the a-Si tower compared to(d)voltage,vs.,AFM scan number.,Schematic diagram of the,in situ,AFM apparatus.,Optical micrograph of a Li-alloy film after expansion,8/7/2023J.R.Dahn,Electrochem,12/3/2024,Y.Cui,Nat.Nanotechnol.,2008,3,31.|Y,.Cui,Nano Lett.2011,11,2949.|G.Yushin,Nat.Mater.,2010,9,353.|,G.A.Ozin,Adv.Funct.Mater.2009,19,1999.|,X.J.Huang,Adv.Mater.2011,23,4938.|,X.P.Qiu,Electrochem.Commun.,2007,5,930.|S.M.Lee,Electrochim.Acta,2008,53,4500.|,J.G.Zhang,J.Electrochem.Soc.,2010,7,A765.|J.R.Dahn,Electrochem.Solid-State Lett.,2007,10,A17.|G.Yushin,ACS Appl.Mater.Inter.,2010,11,3004.|G.Yushin,Science,2011,334,75.,Si based anode,Nano materials,Si array,Current collector,Binder,4,Strategies for silicon anodes,8/7/2023Y.Cui,Nat.Nanotechn,Particle pulverization,“,A strong size dependence of fracture in silicon material was discovered that there exists a critical particle size of,150 nm,below which cracking did not occur.,”,2,Size effect,1 H,Zhang,Nano Letters 2012,12,2778.,;2,XH Liu,ACS Nano.2012,2,15221531,12/3/2024,5,Electrode,Electronic contact,Interface,Stability of SEI film,Particle,Fracture and Pulverization,Current collector;Binder;Array,Stability in Si-based material,?,1,Particle pulverization “A str,Li insertion,Li extraction,Long cycles,12/3/2024,6,The exposed active surface due to the volume change cause continual formation of SEI films and low coulombic efficiency(CE).,Research routes,Reduce the particle size to accommodate SEI film,Design porous or hollow structure to buffer the volume expansion,Composite with C or Metal(Cu)to increase electronic conductivity and modify the interface between Si and electrolyte.,Investigate new binder and electrolyte additives system for Si-based anode materials,Stability of SEI film,Li insertionLi extractionLong,7,5%SiH,4,+95%Ar,5%H,2,&95%Ar,450,C,1 h-2.5 h,Calcination 2,N,2,atmosphere,900,C,4 h,N,2,atmosphere,225,C,1h,500,C,2h,Heating under stirring,Porous carbon,80,C,solvent,evaporation,Calcination 1,Remove template,HCl,Si CVD,Porous Si-C,Nano CaCO,3,Sucrose solution,Deposited silicon,Carbon framework after,1,st,and 2,nd,calcination,12/3/2024,Porous Si/C composite,Synthesis Process,75%SiH4+95%ArCalcination,12/3/2024,Morphology,8,in 1 bold,1 e,Porous structure of carbon substrate can be observed from TEM images,After CVD,silicon particles adhere to the framework and porous structure was maintained.Particle size of silicon is 10 nm and homogeneously dispersed.,The deposited silicon in Porous Si-C is amorphous,as indicated by the absence of crystallites and broad diffuse rings in the SAED patterns.In contrast,when composite is heated to 700 C for 0.5 h,a lattice fringe corresponding to d111=0.31 nm for silicon is seen in Porous Si-C-700.,Results and analysis,SEM and TEM images,8/7/2023Morphology 8 in 1 bold,12/3/2024,9,in 1 bold,1 e,Obvious characteristic peak of crystal silicon after heat treatment at 700,C,for 0.5 h,Three obvious diffraction peaks around 28,47 and 56 are found after heat treatment,which correspond very well to the(111),(220)and(311)peaks of silicon without any impurity peaks.,The peak at 520 cm,-1,(indicative of crystalline silicon)is not detected after silicon CVD.The bands centered around 155,474 cm,-1,and the weak shoulder at 400 cm,-1,are typical features of amorphous silicon vibration modes,1,.,Results and analysis,Structural characterization,1 D.Aurbach,J.Phys.Chem.C,2007,111,11437.,XRD patterns and Raman spectra,8/7/20239 in 1 bold,1 eResult,N,2,sorption isotherms,Pore size distribution,Both porous carbon and porous Si-C show type IV isotherm,which is typical characteristic of mesoporous structure,Obvious decrease of specific surface area(SSA)and pore volume after Si CVD,Porous carbon:,650 m,2,/g,1.32 cc/g,Porous Si-C:,150 m,2,/g,0.39 cc/g,Pores with diameter of 3 nm generated by,decomposition of sucrose,Pores with diameter of 1040 nm due to the removal of CaCO,3,template,which were reduced after Si CVD,Porous Structure,12/3/2024,10,N2 sorption isothermsPore size,Charge-Discharge curves,Cycling performance,1)2,nd,charge capacity;2)VC:vinylene carbonate,12/3/2024,11,Electrochemical performance,1,st,dch capacity:2404 mAh/g,1,st,ch capacity:1541 mAh/g,1,st,coulombic efficiency:64.1%,Reversible capacity,1,:1504 mAh/g,Capacity retention:67%after 200 cycles,Recipe:Porous Si-C:CB:binder(PAA)=6:2:2;Electrolyte:1 M
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