有机硅电解液：安全性与高电压性能研究进展

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=

3、CH2CH3OOEC 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+Nib1433.05.5LiNiSO4F

4、C5.25.42+/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 compoundsSulfonateestersCarboxylanhydridesPh

5、osphidesCCNNnOFCOOOOOCF3FFCF3R4N+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;16

6、0 (2013)A838. J Power Sources, 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

7、(V 4.3 V, corrodes collector) LiBF4 (inferior 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;

8、 Poor compatibility with graphite; Wetting problem with 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 graphiteODisadva

9、ntages: Bad performance at elevatedtemperatures (FEC) Harsh synthesis 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; Elec

10、trochem Commun, 10 (2008) 783.High Low flammability High oxidation resistance 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 stab

11、ility Very low rotation barrieraround Si-O axis, (ca.0.8 KJ/mol) low linear isation energy 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

12、 withalkylcarbonates Medium wide electrochemicalwindow Very low glass transitiontemperature good thermal stabilityAlternative: Organosilicon ElectrolytesOOOOOR2R2R1R1= H, CH3R2= CH3, CH3CH2Carbonate electrolytesHighly flammable!OJ. Mater. Chem., 2008, 18(31), 3713-17; 2010, 20, 8224-26. Chem. Mater.

13、 , 2007, 19, 5734-5741.Implant neuro-stimulator micro cell(27.5 3.2 mm2, 1g)Organosilicon as Safe Electrolytes1. Excellent cyclability；2. Electrochemically stable3. Nonflammable/Safe; 4. Environmental benignConventional electrolytesOS electrolytesMCMB/LiNi0.8Co0.15Al0.05O2,0.8M LiBOB OS electrolytes

14、C/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) 1190Progress on Organosilicon Electrolytes (Lit.) Ionic conductivity Compatibility with graphite Oxidation potential ( 4.2 V )Challenges of OSelectrolytes:Compound

15、s/cPoT/Cg-/mScm1(0)25CE/VcathodicE/VanodicEW/VSN1SN2SN3BNSTNS2.884.627.163.604.6011.612.312.815.717.3-118-111-98.4-107-1061.101.521.201.281.030.00.00.01.111.055.6015.054.494.11NCH2CH2CH2C Si O CH2CH2O CH3nCNCH2CH2Si(CH3)(3-m)(OCH2CH2OCH3)mCH3dielectric constant oxidation poten

16、tial Increaseddielectric constantIncreasedoxidation potentialHighconductivityOrganosilicon Compounds with Nitrile GroupCH3Discharge Capacity (mAh/g)Efficiency (%)Potenial / VSpecific Capacity / mAhg-1Specific capacity/ mAhg-1Capacity retention (%)Specific capacity/ mAhg014012010080601051009590858030

17、00.7C 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, 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

18、number0204060100800.2 C2C1.5 C1C0.5 C0.2 CMisciblewell withcarbonateEnhancedhigh rateperformance0100 200 300 400 5006000.01.02.0-11M LiPF6 in SN11M LiPF6 in BNS/PC (4:6 in vol.)1M LiPF6 in TNSAs EO arm increase,More compatibilitywith graphite.Organosilicon Compounds with Nitrile Group3.0Cyc

19、le numberJ. Power Sources, 254, 29-32 (2014)Coulombic Efficiency / %Specific capacity/ mAhg-102040608010008040160120Cycle number8081971009998Retention: 90.4%100 cyclesCE 99.5%LCO/graphite, 3.0-4.4 V0.5C, 143 mAhg-1Comparison with Commercial High-VoltageElectrolytesOur high-voltage OS electrolyte (OS

20、 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 propertiesFluorinationFluorinated OS Compounds with Oligo (EO)1S3M2, J. Mater. Chem., 2010, 20, 8224; F2MSEO2M unpublished data.-1

21、dQ/dVCap. mAh/gSpecific capacity/ mAhgCoulombic efficiency / %Potential (V vs. Li+/Li)F2MSEO2M / 1M LiPF6+0.2MLiODFB0204060804016012080200240Cycle number4.4VLCO/Li, 0.2C8010095908510090.8%95.8%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

22、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 retentionSpecific capacity (mAh/g)Current ()Efficiency (%)Potential ( V vs. Li /Li )0204060801006080120

23、100180160140200Cycle number040208060100LCO / TMOSC3GC / graphite2.7-4.4 V, C/10Highly polargroupDielectricconstant Concentrationof Li+-1012345+TMOSC3GCTEOSC3GCDSC3GCOOOOSiOOSiOSiOOOOWang JL, et al., 2013, to be submittedCarbonate Functionalized Trialkoxysilanes(RO)3Si(CH2)nOOOOR= CH3O, CH3CH2O; n= 0

24、,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: 10 mv/s(a)OS based electrolytes for 4.4V LCO/graphite cellcommercial

25、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 0.5CCycle numbercommercial carbonate electrolyte: GT303+ 2%wt. VC+

26、 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 electrolytecommerical carbonate electrolyte+30

27、% 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 Imidazolium ILs: ca. 4V Tertr

28、aalkylammonium 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

29、 LiquidsAdvantages 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 2

30、010029970 A1; WO 2009045609 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 4Pote

31、ntial (V)SN1IL-TFSIAN1IL-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 nu

32、mber0.2C020806040100120Cell Performances 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% (1

33、00 cycle)SN1IL-TFSI-EMC-1-102462202001801601401201008060402008 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 number28

34、Graphite/NMC, 2.7-4.5 V, 0.2C2%PS 0.2M LiODFB 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

35、(1:1 by vol.)Capacity/mAh140001200010000800060004000200000100200300400500600700E12A084-1668 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 RT

36、Discharge: 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 Energ

37、y Navigation lightCollaboration：GD Maritime Safety Administration (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.

38、Capacity retentionSi77.1%270698.8%1365.0%SiC79.7%105498.4%49546.9%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 (L

39、B303)SiC anode (LB303+FEC)SiC anode (LB303+BNS)40 60Cycle number1008060020406080100100806040200120Si 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 (%)

40、Columbic efficiency (%)Current density: 400mA/g68% capacity retention05010015020010000200040003000SiC (LB303)SiC (LB303+FEC)SiC (LB303+BNS)200406010080LB303+BNSSi85.9%262199.7%1696Cycle numberCurrent density: 600mA/gElectrolyteElectrode1st CE1st reversible capacity200th CE200th reversible capacity05

41、02001000020003000400060005000Si anode (LB303+BNS)100 150Cycle numberCurrent density: 600mA/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

42、(a.u.)Intensity (a.u.)Intensity (a.u.)Raman shift (cm )Raman shift (cm )Raman shift (cm )Raman 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5001000

43、1500SiLB303LB303+FECLB303+BNS-1Delithiation at 1.5V500100015002000Si befor cycle50010001500Si-SistretchingLB303LB303+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 (c

44、m )500100015002000SiCLB303LB303+FECLB303+BNSSi-O-SibendingLithiation at 0.01VSi-O stretching vibrationin Li2Si2O5-15001000 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.

45、 Non-Cryst. Solids 2006 , 352 , 4101 .5001000 15002000SiC anode before cycle-1AnodeSiSiCElectrolyteLithiationDelithiationLithiationDelithiationLB3033.6%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(Delithiatio

46、n)LB303(Delithiation)KevOCLB303(Lithiation)FSiSi anode0.51.02.02.5LB303+BNS(Delithiation)LB303+BNS(Lithiation)LB303(Delithiation)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

47、定的SEI膜Transmission (a.u.)Transmission (a.u.)Transmission (a.u.)5002500Delithiation1000 1500 2000Wavenumber (cm-1)LithiationLB303+FECSi 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、

48、(LB303+FEC) 870：LiPF61640, 1450,1090, 1810: 为FEC分解产物（Ref: Langmuir 2011, 28, 965-976）5001000150020002500*Si anodeLB303+BNSDelithiationLithiationWavenumber (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

49、 (a.u.)Transmission (a.u.)SiC anode5002500LB303+FECLithiationDelithiationSiC anode1000 1500 2000Wavenumber (cm-1)5001000150020002500DelithiationLithiationWavenumber (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+ 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 (