1、有机硅电解液：安全性和高电压性能研究进展1、Background Safety issues related with Li-ion Batteries Safe electrolytes for high-voltage batteries2、Organosilicon based electrolytes High-voltage OS-based electrolytes OS-based electrolytes for Si anodes4、SummaryOutlineSafety issues of LIBs:High flammability ofcarbonate electr
2、olytes!LiFePO4 batteryNot safe enough！Safety of Lithium-Ion BatteriesSafety(abuse tolerance):When overcharged,thermalrunaway leads to fires etc.Runaway reaction caused byrelease of oxygen from cathodematerials(e.g.,LiCoO2).The development of newSafe electrolyte materials!OOORRDMC:R=CH3DEC:R=CH2CH3OO
3、EC OHighVoltageCathodeMaterialsDischargepotential(V)RedoxcoupleTheoreticalCapacity(mAh/g)PotentialRange(V)LiCoPo44.82+/3+Co1673.05.1LiNiPo45.12+/3+Ni1673.05.5Li3V2(PO4)3LiMPO43.83+/4+/5+V1973.04.8Li2CoP2O74.92+/3+Cob1092.05.5Li2MnP2O74.452+/3+Mnb1102.04.7Li2NiPO4F5.12+/3+Nib1433.05.5LiNiSO4FC5.25.42
4、+/3+Ni149Es=Qcapacity*Vvoltage1.Safety!2.High-voltage Stability!J.Power Sources,237(2013)229.High-voltage cathodes require compatible electrolytesElectrolyte Challenges:NSAdditivesDinitrilesIonic liquidsSulfoneFluorinated solventInorganic compoundsSulfonateestersCarboxylanhydridesPhosphidesCCNNnOFCO
5、OOOOCF3FFCF3R4N+R2OCFR1OFR1N+R2O-CF FFR1N+R2R3O SFOOSSOOOOSOOOOSOOOOSOOSOCF3CF3F3CF3CF3CCF3OPOOOOOBOOOOOLiBOOOOFFLiElectrolyte solvents and additives for high-voltageSolventsLiBOBLiODFBCNH HCn C NLiNi0.5Mn1.5O4/Li,3.5-4.9V,1/12 CJ Electrochem Soc,156(2009)A60.;159(2012)A370;160(2013)A838.J Power Sou
6、rces,189(2009)576.Aprotic aliphatic dinitrile solventsn=3ADN,n=5 PMNn=6 SUN,n=8 SENAdvantages:Electrochemical window(7-8V)Flash point(110,163 forADN)Dielectric constant(20-30,55 for SCN)Disadvantages:Poor compatibility with graphitePoor solubility of LiPF6 LiTFSI (V 4.3 V,corrodes collector)LiBF4(in
7、ferior ability,poor lowtemperature performance)J Electrochem Soc,149(2002)A920;J Phys Chem B,115(2011)12120.Electrochem Commun,11(2009)1418;11(2009)1073.Sulfone-Based Electrolytes Advantages:High oxidationpotential Low flammable High melting point;Poor compatibility with graphite;Wetting problem wit
8、h separatorLi4Ti5O12/1M LiPF6FEC/DMC/D2 3/4/3/LiNi0.5Mn1.5O4 (Data from ANL,USA)OFRf1Rf2OD2OFEC1 C at 55oCFluorinated Based ElectrolytesAdvantages:High oxidative stability High flash point/lowflammability(Safe)Compatible with graphiteODisadvantages:Bad performance at elevatedtemperatures(FEC)Harsh s
9、ynthesis conditions/highcost1M LiPF6 EC/DEC(3/7)1M LiPF6 EC/DMC/MFA(3/3/4)F OH C C O CH3FMFA1M LiPF6 MFALiCo2/Graphite cell(1 Ah cell);Daikindata(Japan)Fluorinated Based ElectrolytesEnergy&Environmental Science,6(2013)1806;Electrochem Commun,10(2008)783.High Low flammability High oxidation resistanc
10、e High viscosity(low conductivity&ratecapability)Poor wettingHigh costJ Power Sources,189(2009)331;225(2013)113;233(2013)115.Mix with carbonate or other co-solventperformance Ionic Liquid Electrolytesthermal stability Very low rotation barrieraround Si-O axis,(ca.0.8 KJ/mol)low linear isation energy
11、 ofthe Si-O-Si angle(1.3kJ/mol).Organosilicon(OS)Electrolytes:High ionic conductivity Non-flammability:Biocompatible Excellent wetting capability Wide liquid phase range(-40200 oC)Low viscosity-comparable withalkylcarbonates Medium wide electrochemicalwindow Very low glass transitiontemperature good
12、 thermal stabilityAlternative:Organosilicon ElectrolytesOOOOOR2R2R1R1=H,CH3R2=CH3,CH3CH2Carbonate electrolytesHighly flammable!OJ.Mater.Chem.,2008,18(31),3713-17;2010,20,8224-26.Chem.Mater.,2007,19,5734-5741.Implant neuro-stimulator micro cell(27.5 3.2 mm2,1g)Organosilicon as Safe Electrolytes1.Exce
13、llent cyclability；2.Electrochemically stable3.Nonflammable/Safe;4.Environmental benignConventional electrolytesOS electrolytesMCMB/LiNi0.8Co0.15Al0.05O2,0.8M LiBOB OS electrolytesC/5,3.0 to 4.0 V;100%efficiencyJ Power Sources,228(2013)32;196(2011)2255Electrochem Commun,8(2006)429;Chem Commun,49(2013
14、)1190Progress on Organosilicon Electrolytes(Lit.)Ionic conductivity Compatibility with graphite Oxidation potential(4.2 V)Challenges of OSelectrolytes:Compounds/cPoT/Cg-/mScm1(0)25CE/VcathodicE/VanodicEW/VSN1SN2SN3BNSTNS2.884.627.163.604.6011.612.312.815.717.3-118-111-98.4-107-1061.101.521.201.281.0
15、30.00.00.01.111.095.125.115.055.605.205.125.115.054.494.11NCH2CH2CH2C Si O CH2CH2O CH3nCNCH2CH2Si(CH3)(3-m)(OCH2CH2OCH3)mCH3dielectric constant oxidation potential Increaseddielectric constantIncreasedoxidation potentialHighconductivityOrganosilicon Compounds with Nitrile GroupCH3Discharge Capacity(
16、mAh/g)Efficiency(%)Potenial/VSpecific Capacity/mAhg-1Specific capacity/mAhg-1Capacity retention(%)Specific capacity/mAhg01401201008060105100959085803000.7C CC to 4.4V,0.5C DC to 3.0 V274 cycles:85.2%LCO/OS co-solvent/Graphite50 100 150 200 250Cycle number016014012010080604020180LCO/graphite,2.7-4.4V
17、,0.2CBNS/0.4 M LiODFB+0.6 M LiPF6TNS/0.4 M LiODFB+0.6 M LiPF6SN1/0.4 M LiODFB+0.6 M LiPF640 80 120 160052530030906012018015010 15 20Cycle number0204060100800.2 C2C1.5 C1C0.5 C0.2 CMisciblewell withcarbonateEnhancedhigh rateperformance0100 200 300 400 5006000.01.00.51.52.52.0-11M LiPF6 in SN11M LiPF6
18、 in BNS/PC(4:6 in vol.)1M LiPF6 in TNSAs EO arm increase,More compatibilitywith graphite.Organosilicon Compounds with Nitrile Group3.0Cycle numberJ.Power Sources,254,29-32(2014)Coulombic Efficiency/%Specific capacity/mAhg-102040608010008040160120Cycle number8081971009998Retention:90.4%100 cyclesCE 9
19、9.5%LCO/graphite,3.0-4.4 V0.5C,143 mAhg-1Comparison with Commercial High-VoltageElectrolytesOur high-voltage OS electrolyte(OS Ionic Liquids)101Comp.Viscosity（mPa.s）DielectricconstantTg()Conductivity-1（mS.cm）Oxidationpotential(V)FMSEOM221.799.5-108.51.464.951SM322.14.44-1120.9?Enhanced physical prop
20、ertiesFluorinationFluorinated OS Compounds with Oligo(EO)1S3M2,J.Mater.Chem.,2010,20,8224;F2MSEO2M unpublished data.-1dQ/dVCap.mAh/gSpecific capacity/mAhgCoulombic efficiency/%Potential(V vs.Li+/Li)F2MSEO2M/1M LiPF6+0.2MLiODFB0204060804016012080200240Cycle number4.4VLCO/Li,0.2C8010095908510090.8%95.
21、8%4.5V0.00.1 0.2 0.3 0.40.5Graphite/Li,0.01-3.0 V1 M LiPF6 PC:DMC:DEC:F2MSEO2M(28:35:35:2 vol.)Unpublished dataFluorinated OS Compounds with Oligo(EO)Good compatibility with1020Cycle#3040320280graphite!400360High voltage performances:LCO/C cell,94 cycles4.4V:96%capacity retention4.5V:90%capacity ret
22、entionSpecific capacity(mAh/g)Current()Efficiency(%)Potential(V vs.Li/Li)0204060801006080120100180160140200Cycle number040208060100LCO/TMOSC3GC/graphite2.7-4.4 V,C/10Highly polargroupDielectricconstant Concentrationof Li+-1012345+TMOSC3GCTEOSC3GCDSC3GCOOOOSiOOSiOSiOOOOWang JL,et al.,2013,to be submi
23、ttedCarbonate Functionalized Trialkoxysilanes(RO)3Si(CH2)nOOOOR=CH3O,CH3CH2O;n=0,2,3ODielectric constant as high as37.8!220Current/A3.03.54.04.55.05.56.0320240160800Voltage/V vs.Li/Li+commerical carbonate electrolytecommerical carbonate electrolyte+30%SN1W.E.platinumC.E.lithiumR.E.lithiumScan rate:1
24、0 mv/s(a)OS based electrolytes for 4.4V LCO/graphite cellcommercial carbonate electrolyte:GT303(LB303)commercial carbonate electrolyte+30%SN1:GT303+30%SN1-1Specific capacity/mAhg030609012015012010080commercial carbonate electrolytecommercial carbonate electrolyte+30%SN1LCO/graphite,3.0-4.4V 0.5CCycl
25、e numbercommercial carbonate electrolyte:GT303+2%wt.VC+2%wt.PScommercial carbonate electrolyte+30%SN1:70%TC 4.35+30%SN1,0.1 M LiODFB+1 M LiPF6,2%wt.VC+2%wt.PSOS based electrolytes for 4.4V LCO/graphite cell(b)160140-1Specific capacity/mAhg01020304050601000.2C0.5C0.7C1C1.5Ccommerical carbonate electr
26、olytecommerical carbonate electrolyte+30%SN10.2C(c)160140120Cycle numbercommercial carbonate electrolyte:GT303+2%wt.VC+2%wt.PScommercial carbonate electrolyte+30%SN1:70%TC 4.35+30%SN1,0.1 M LiODFB+1 M LiPF6,2%wt.VC+2%wt.PSOS based electrolytes for 4.4V LCO/graphite cellElectrochemical windows Imidaz
27、olium ILs:ca.4V Tertraalkylammonium ILs:ca.6VR=(CH3)3SiCH2,(CH3)3CCH2A=N(CF3SO2)2,BF4J.Phys.Chem.B,109,21576(2005);111,4819(2007);111,4885(2007);Talanta,71,68(2007).N +N R-A+Si NN C4H9-PF6 TertraalkylPhosphonium ILs:excellent thermal stabilityElectrochim.Acta,51,5567(2006)Organosilicon Based Ionic L
28、iquidsAdvantages Over Carbon Analogues Weake Intermolecular interactions Lower viscosity Low glass transition temperature HydrophobicX=N,P;n=1,3;R1=CH3,CH3CH2;R2=Alkyl,alkoxyA=BF4,PF6,TFSI,BOB,NCN2R2R2 SiR2(CH2)nXR1(OCH2CH3)2-AOOOOOOOF3C S N S CF3O OTFSIBO OBOBAnion structures:US 2010029970 A1;WO 20
29、09045609 A1;CHN Pat:CN201010265833.2Organosilicon Based Ionic LiquidsMass Retaintion(%)Current()OSIonic LiquidSN1IL-TFSIAN1IL-TFSICETMA-TFSImS/cm1.354.291.10cp125.436.0-TdecoC362325329EanodicV0.000.651.30EcathodicV5.395.305.78Novel Organosilicon Based Ionic Liquids012563 4Potential(V)SN1IL-TFSIAN1IL
30、-TFSICEN1IL-TFSI0100500600120100806040200SN1IL-TFSIAN1IL-TFSICEETMAIL-TFSI200 300 400oTemperature(C)Capacity(mAh/g)Capacity(mAh/g)Efficiency(%)Efficiency(%)00301501209060180010 20 30 40 50 60 70 80 90Cycle2080604010005253003015012090601800.2C2C1.5C1C0.5C10 15 20Cycle number0.2C020806040100120Cell Pe
31、rformances for Novel OS Ionic LiquidsLCO/Graphite,2.7-4.4 V,0.2CSN1IL-TFSI:DMC=1:1 by vol.210Capacity(mAh/g)Efficiency(%)Capacity(mAh/g)Efficiency(%)0102030405060708090100220200180160140120100806040200Cycle Number100806040200NMC-LI cell;CapacityRetention:96%(100 cycle)SN1IL-TFSI-EMC-1-10246220200180
32、1601401201008060402008 10 12 14 16 18 20 22 24 26 28 30Cycle Number100806040200NMC/graphite(2.7-4.6V)SN1IL-TFSI-EMC-1-1Cell Performances for Novel OS Ionic LiquidsCoulombic efficiency/%Specific capacity/mAhg-1051015202530350804020016012004020Cycle number28Graphite/NMC,2.7-4.5 V,0.2C2%PS 0.2M LiODFB
33、0.8 M LiPF6 BNSBNS for 4.5 V graphite/NMC cellProvided by YTQ1008060Specific capacity/mAhg-1Efficiency(%)05101520250Cycle number(a)210180150120906030010080604020SN1IL-TFSI for 4.5 and 4.6 V graphite/NMC2.7-4.6 V2.7-4.5 VGraphite/NMC0.2CSN1IL-TFSI/EMC(1:1 by vol.)Capacity/mAh1400012000100008000600040
34、00200000100200300400500600700E12A084-1668 Cycle；83.53%EST:811 Cycle；80%10AAE7365270PM3HSE)-11500mAhCommercialization of OS ElectrolytesNMC/OS Electrolyte/C Battery(10 Ah)Number of CycleCharge:CC 10Ato 4.2V;CV 4.2V to 3.5hr or 200mAcut-off at RTDischarge:10A to 2.75V at RT采测一1s采集一个数据两种电解液的电池在穿刺测试过程中温
35、升趋势和最高温度均没有明显差异，即电池内部的放热反应方式和程度没有变化，但有机硅电解液能有效抑制易燃成分的燃烧。有机硅电解液与商业电解液三元动力电池（10 Ah)针刺安全性对比有机硅电解液电池烟雾喷射力度较小，地上的黑色物质少商业电解液电池烟雾喷射力度较大，地上的黑色物质多，部分电池会着火爆炸OS electrolyte batteryPack(10.8V，100Ah)Demonstration of OS Battery PackApplication:Solar Energy Navigation lightCollaboration：GD Maritime Safety Administ
36、ration(广州航标局）SiC compositeCompatability of OS Electrolyte with Si AnodeDischarge capacity(mAh/g)Capacity retention(%)Columbic efficiency(%)ElectrolyteLB303LB303+FECLB303+BNSElectrode1st CE1st reversible cap.100th CE100th reversible cap.Capacity retentionSi77.1%270698.8%1365.0%SiC79.7%105498.4%49546.
37、9%Si86.4%308998.7%128841.7%SiC84.2%107596.0%84178.2%Si86.1%334899.4%203560.8%SiC82.0%113996.9%100388.1%Current density:400mA/g02080100010008000700060005000400030002000Si anode(LB303)Si anode(LB303+FEC)Si anode(LB303+BNS)SiC anode(LB303)SiC anode(LB303+FEC)SiC anode(LB303+BNS)40 60Cycle number1008060
38、020406080100100806040200120Si anode(LB303+BNS)SiC anode(LB303)SiC anode(LB303+FEC)SiC anode(LB303+BNS)Cycle numberSi anode(LB303)Si anode(LB303+FEC)Discharge capacity(mAh/g)Discharge capacity(mAh/g)Columbic efficiency(%)Columbic efficiency(%)Current density:400mA/g68%capacity retention05010015020010
39、000200040003000SiC(LB303)SiC(LB303+FEC)SiC(LB303+BNS)200406010080LB303+BNSSi85.9%262199.7%1696Cycle numberCurrent density:600mA/gElectrolyteElectrode1st CE1st reversible capacity200th CE200th reversible capacity0502001000020003000400060005000Si anode(LB303+BNS)100 150Cycle numberCurrent density:600m
40、A/g6050708010090SiCSi纳米硅颗粒负极材料极片在商业电解液和使用了FEC添加剂时，极片在首次嵌脱锂后电极出现明显的脱落，在使用了有机硅电解质（BNS）为添加剂时，极片脱落现象明显改善。与裸硅负极材料相比，经过碳包覆后制备出的碳硅复合材料极片在使用商业电解液时，经过嵌脱锂后有部分剥落，但情况比裸硅电极已有改善。当使用了FEC和BNS为添加剂时有明显的改善，极片并为出现类似的剥落现象。Intensity(a.u.)Intensity(a.u.)Intensity(a.u.)Raman shift(cm )Raman shift(cm )Raman shift(cm )Raman
41、dataRef:1 Adv.Mater.2013,25,449845032 J.Non-Cryst.Solids 2006,352,4101.1、BNS作为添加剂易于在Si表面形成含有Si-O-Si的SEI膜2、与传统 的SEI膜不同，形成的这种SEI膜可能有一定的脱嵌锂活性(Li2Si2O5)3、在脱锂后，BNS作为添加剂时产生的SEI膜较其它两种电解液相比能稳定存在50010001500SiLB303LB303+FECLB303+BNS-1Delithiation at 1.5V500100015002000Si befor cycle50010001500Si-SistretchingL
42、B303LB303+FECLB303+BNS-1Si-O-Sibendingin Li2Si2O5-1Lithiation at 0.01VSi-O stretching vibrationSiIntensity(a.u.)Intensity(a.u.)Intensity(a.u.)Raman shift(cm )Raman shift(cm )Raman shift(cm )500100015002000SiCLB303LB303+FECLB303+BNSSi-O-SibendingLithiation at 0.01VSi-O stretching vibrationin Li2Si2O5
43、-15001000 15002000SiCDelithiation at 1.5VLB303LB303+FECLB303+BNSG bandD band-11、BNS作为添加剂在SiC表面形成含有Si-O-Si的SEI膜2、由于有包覆碳层的存在，以FEC和BNS作为添加剂时产生的SEI膜都较稳Ref:1Adv.Mater.2013,25,449845032 J.Non-Cryst.Solids 2006,352,4101.5001000 15002000SiC anode before cycle-1AnodeSiSiCElectrolyteLithiationDelithiationLith
44、iationDelithiationLB3033.6%46.4%1.8%2.4%LB303+FEC5.5%26.8%4.8%6.3%LB303+BNS14.2%8.6%6.8%9.5%Intensity(a.u.)Intensity(a.u.)1.52.02.5LB303+BNS(Lithiation)LB303+BNS(Delithiation)LB303(Delithiation)KevOCLB303(Lithiation)FSiSi anode0.51.02.02.5LB303+BNS(Delithiation)LB303+BNS(Lithiation)LB303(Delithiatio
45、n)LB303(Lithiation)SiCanodeSiFOC1.5Kev0.5 1.0Si 元素含量分析1、LB303和LB303+FEC:Si电极在循环后表面硅含量猛增，SEI膜的破坏硅的裸露2、BNS作为添加剂时产生的SEI膜中Si含量高于LB303形成的，证明Si成分参与成膜3、在SiC中碳层的存在对三种电解液来说都有利形成更加稳定的SEI膜Transmission(a.u.)Transmission(a.u.)Transmission(a.u.)5002500Delithiation1000 1500 2000Wavenumber(cm-1)LithiationLB303+FECS
46、i anode5002500DelithiationLithiationLB303Si anode1000 1500 2000Wavenumber(cm-1)*1、(LB303)870：LiPF6峰的相对强度明显减小，说明经过脱锂后SEI的分解（Ref:J.Phy.Chem.C 2011,28,965-976）2、(LB303+FEC)870：LiPF61640,1450,1090,1810:为FEC分解产物（Ref:Langmuir 2011,28,965-976）5001000150020002500*Si anodeLB303+BNSDelithiationLithiationWaven
47、umber(cm-1)3、(LB303+BNS)870：LiPF6峰的相对强度减小不明显，说明经过生成的SEI较为稳定，对比三种电解液，1060处的Si-O-Si 键明显增强，证实了SEI膜中的Si-O-Si成分，脱锂后任然能够稳定存在Transmission(a.u.)Transmission(a.u.)Transmission(a.u.)SiC anode5002500LB303+FECLithiationDelithiationSiC anode1000 1500 2000Wavenumber(cm-1)5001000150020002500DelithiationLithiationW
48、avenumber(cm-1)500 1000 1500 2000 2500SiC anodeLB303DelithiationLithiationWavenumber(cm-1)LB303+BNS1、SEI结构分析参考Si anode2、与Si电极不同，由于C的存在，形成的SEI膜更加稳定(870：LiPF6峰的相对强度在脱锂后变化没有Si电极那么明显）Si anode(Electrolyte:LB303)发生膨胀 Lithiation at 0.01V发生收缩开裂 Delithiation at 1.5V生成的SEI膜生成的SEI膜碎裂Si anode(Electrolyte:LB303+
49、10%BNS)较小膨胀 Lithiation at 0.01V并未发生收缩开裂 Delithiation at 1.5V生成的SEI膜生成的SEI膜稳定存在SiC anode(Electrolyte:LB303)发生一定的膨胀 Lithiation at 0.01V发生收缩 Delithiation at 1.5V生成的SEI膜生成的SEI膜有些消失但是跟裸硅电极相比还是更加稳定的，由于有碳层的存在SiC anode(Electrolyte:LB303+10%BNS)较小的膨胀 Lithiation at 0.01V发生一定的收缩 Delithiation at 1.5V生成的SEI膜生成的稳
50、定的SEI膜-Z ()-Z ()-Z ()050100150200250300300250200150100500Z ()02004006008001000 1200 14002001000300400600500LB303Si anode(berfore cycle)Si anode(after Lithiation)Si anode(after Delithiation)Z ()LB303+BNSSi anode(berfore cycle)Si anode(after Delithiation)Si anode(after Lithiation)010020030040050060010
