有機(jī)硅電解液：安全性和高電壓性能研究進(jìn)展

1、有機(jī)硅電解液：安全性和高電壓性能研究進(jìn)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;

10、Electrochem 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 Electrolytesther

11、mal stability 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- co

12、mparable 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

13、. Mater. , 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 elec

14、trolytesC/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:

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

16、on potential Increaseddielectric constantIncreasedoxidation potentialHighconductivityOrganosilicon Compounds with Nitrile GroupCH3Discharge Capacity (mAh/g)Efficiency (%)Potenial / VSpecific Capacity / mAhg-1Specific capacity/ mAhg-1Capacity retention (%)Specific capacity/ mAhg0140120100806010510095

17、9085803000.7C 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

18、20Cycle 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 Gro

19、up3.0Cycle 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 electro

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 Chem., 2010, 20, 8224; F2MSEO2M unpublished

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

22、blished 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 )02040608010

23、06080120100180160140200Cycle 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, CH3CH

24、2O; 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: 10 mv/s(a)OS based electrolytes for 4.4V LCO/graphite cellcom

25、mercial 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

26、%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 electrolytecommerical carbonate electr

27、olyte+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 Imidazolium ILs: ca.

28、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 Bas

29、ed Ionic 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 structu

30、res:US 2010029970 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 Liquids0125

31、63 4Potential (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 20

32、Cycle number0.2C020806040100120Cell 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

33、: 96% (100 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

34、number28Graphite/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-T

35、FSI/EMC (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-o

36、ff at RTDischarge: 10A to 2.75V at RT采測一1s采集一個數(shù)據(jù)兩種電解液的電池在穿刺測試過程中溫升趨勢和最高溫度均沒有明顯差異，即電池內(nèi)部的放熱反應(yīng)方式和程度沒有變化，但有機(jī)硅電解液能有效抑制易燃成分的燃燒。有機(jī)硅電解液與商業(yè)電解液三元動力電池（10 Ah)針刺安全性對比有機(jī)硅電解液電池?zé)熿F噴射力度較小，地上的黑色物質(zhì)少商業(yè)電解液電池?zé)熿F噴射力度較大，地上的黑色物質(zhì)多，部分電池會著火爆炸OS electrolyte batteryPack (10.8V，100Ah)Demonstration of OS Battery PackApplication: Sol

37、ar Energy Navigation lightCollaboration：GD Maritime Safety Administration (廣州航標(biāo)局）SiC compositeCompatability of OS Electrolyte with Si AnodeDischarge capacity (mAh/g)Capacity retention (%)Columbic efficiency (%)ElectrolyteLB303LB303+FECLB303+ BNSElectrode1st CE1st reversible cap.100th CE100th reversi

38、ble cap.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

39、anode (LB303)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 effici

40、ency (%)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 ca

41、pacity0502001000020003000400060005000Si anode (LB303+BNS)100 150Cycle numberCurrent density: 600mA/g6050708010090SiCSi納米硅顆粒負(fù)極材料極片在商業(yè)電解液和使用了FEC添加劑時，極片在首次嵌脫鋰后電極出現(xiàn)明顯的脫落，在使用了有機(jī)硅電解質(zhì)（BNS）為添加劑時，極片脫落現(xiàn)象明顯改善。與裸硅負(fù)極材料相比，經(jīng)過碳包覆后制備出的碳硅復(fù)合材料極片在使用商業(yè)電解液時，經(jīng)過嵌脫鋰后有部分剝落，但情況比裸硅電極已有改善。當(dāng)使用了FEC和BNS為添加劑時有明顯的改善，極片并為出現(xiàn)類似的剝落現(xiàn)象。In

42、tensity (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作為添加劑易于在Si表面形成含有Si-O-Si的SEI膜2、與傳統(tǒng) 的SEI膜不同，形成的這種SEI膜可能有一定的脫嵌鋰活性(Li2Si2O5)3、在脫鋰后，BNS作為添加劑時產(chǎn)生的SEI膜較其它兩種電解液相比能穩(wěn)定存

43、在50010001500SiLB303LB303+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

44、shift (cm )500100015002000SiCLB303LB303+FECLB303+BNSSi-O-SibendingLithiation at 0.01VSi-O stretching vibrationin Li2Si2O5-15001000 15002000SiCDelithiation at 1.5VLB303LB303+FECLB303+BNSG bandD band-11、BNS作為添加劑在SiC表面形成含有Si-O-Si的SEI膜2、由于有包覆碳層的存在，以FEC和BNS作為添加劑時產(chǎn)生的SEI膜都較穩(wěn)Ref: 1Adv. Mater. 2013, 25, 4498

45、45032 J. 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(Del

46、ithiation)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電極在循環(huán)后表面硅含量猛增，SEI膜的破壞硅的裸露2、 BNS作為添加劑時產(chǎn)生的SEI膜中Si含量高于LB303形成的，證明Si成分參與成膜3、在SiC中碳層的存在對三種電解液來說

47、都有利形成更加穩(wěn)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峰的相對強(qiáng)度明顯減小，說明經(jīng)過脫鋰后SEI的分解（Ref: J. Phy. Chem. C 2011, 28, 96

48、5-976）2、(LB303+FEC) 870：LiPF61640, 1450,1090, 1810: 為FEC分解產(chǎn)物（Ref: Langmuir 2011, 28, 965-976）5001000150020002500*Si anodeLB303+BNSDelithiationLithiationWavenumber (cm-1)3、(LB303+BNS) 870：LiPF6峰的相對強(qiáng)度減小不明顯，說明經(jīng)過生成的SEI較為穩(wěn)定，對比三種電解液，1060處的Si-O-Si 鍵明顯增強(qiáng)，證實(shí)了SEI膜中的Si-O-Si成分，脫鋰后任然能夠穩(wěn)定存在Transmission (a.u.)Tran

49、smission (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結(jié)構(gòu)分析參考Si anode2、 與Si電極不同，由于C的存在，形成的SEI膜更加穩(wěn)定(870：LiPF6峰的相對強(qiáng)度在脫鋰后變化沒有Si電極那么明顯）Si anode (Electrolyte:LB303)發(fā)生膨脹 Lithiation at 0.01V發(fā)生收縮開裂 Delithiation at 1.5V生成的SEI膜生成的SEI膜碎裂Si anode (Electrolyte: LB303+ 10% BNS)較小膨脹 Lithiation at 0.01V并未發(fā)生收縮開裂 Delithiation at 1.5V生成的SEI膜生成的SEI膜穩(wěn)定存在SiC anode (Ele